WO2025179067A1

WO2025179067A1 - Systems and methods for intramyocardial ablation

Info

Publication number: WO2025179067A1
Application number: PCT/US2025/016665
Authority: WO
Inventors: Robert Jay LEDERMAN; Rim Nabil HALABY
Original assignee: National Institutes of Health NIH
Current assignee: National Institutes of Health NIH
Priority date: 2024-02-20
Filing date: 2025-02-20
Publication date: 2025-08-28
Anticipated expiration: 2026-08-20

Abstract

A catheter system for performing intramyocardial ablation is provided. In one example, a microcatheter includes a flexible catheter tube having a rounded or tapered nosecone and a conductive ablation electrode coupled to the catheter tube near a distal tip of the catheter tube, the ablation electrode including one or more openings to facilitate delivery of fluid out of the ablation electrode.

Description

SYSTEMS AND METHODS FOR INTRAMYOCARDIAL ABLATION

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to U.S. Provisional Application No. 63/555,802, filed February 20, 2024, and entitled “SYSTEMS AND METHODS FOR INTRAMYOCARDIAL ABLATION.” The present application also claims priority to U.S. Provisional Application No. 63/716,145, filed November 4, 2024, and entitled “SYSTEMS AND METHODS FOR AN ABLATION CATHETER FOR INTRAMYOCARDIAL ABLATION.” The present application also claims priority to U.S. Provisional Application No. 63/716,158, filed November 4, 2024, and entitled “SYSTEMS AND METHODS FOR A MYOCARDIAL ACCESSOR CATHETER FOR INTRAMYOCARDIAL ABLATION.” Each of the aboveidentified applications is hereby incorporated by reference for all purposes.

FIELD

[0002] The present description relates generally to an apparatus for deep myocardial ablation, and methods for deep myocardial ablation.

BACKGROUND/SUMMARY

[0003] Ventricular tachycardia (VT) is a form of heart arrhythmia originating in the ventricles of the heart. Arrhythmias can originate from scar tissue or damage in the ventricular myocardium or from areas of increased automaticity. In some cases, VT can be treated by performing ablation on scarred or damaged tissue within the ventricles to interrupt the electrical signals causing VT. Typically, ablation is carried out on endocardial and/or epicardial surfaces. However, arrhythmia sources in the left ventricular (LV) summit, inter-ventricular septum, papillary muscles, and other LV intramyocardial sites have been difficult to access from the endocardial and epicardial surfaces for ablation. Consequently, high recurrence rates in VT are associated with these sites.

[0004] In one example, the issues described above may be addressed by a microcatheter for intramyocardial navigation and ablation, the microcatheter including a flexible catheter tube having a rounded or tapered nosecone and a conductive ablation electrode positioned near a distal tip of the catheter tube, the ablation electrode including one or more openings to facilitate delivery of fluid out of the ablation electrode. [0005] It should be understood that the brief description above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The present disclosure will be better understood from reading the following description of non-limiting embodiments, with reference to the attached drawings, wherein below: [0007] FIG. 1 depicts an example ablation catheter system;

[0008] FIG. 2 depicts a first view of an ablation catheter and navigation guidewire of the ablation catheter system of FIG. 1;

[0009] FIG. 3 depicts the ablation catheter and navigation guidewire of FIG. 2 arranged within an accessor catheter of a guiding catheter system;

[0010] FIG. 4 depicts hub ends of the ablation catheter system and the guiding catheter system;

[0011] FIG. 5 depicts another view of the hub ends;

[0012] FIG. 6 depicts a magnified view of a proximal end of the accessor catheter;

[0013] FIGS. 7-10 schematically show the guiding catheter system facilitating access to the myocardium and supporting the ablation catheter system therein;

[0014] FIG. 11 is a flow chart illustrating a method for performing an ablation procedure with an ablation catheter system guided by a guiding catheter system as disclosed herein;

[0015] FIG. 12 schematically shows an example kit including aspects of the guiding catheter system as disclosed herein;

[0016] FIG. 13 depicts a second view of the ablation catheter of the catheter system of FIG. 1;

[0017] FIG. 14 depicts a third view of the ablation catheter of the catheter system of FIG. 1;

[0018] FIG. 15 depicts a fourth view of the ablation catheter of the catheter system of FIG. 1;

[0019] FIG. 16 depicts a fifth view of the ablation catheter of the catheter system of FIG. 1; and [0020] FIG. 17 depicts a sixth view of the ablation catheter of the catheter system of FIG. 1

[0021] FIGS. 18 and 19 show cross-sectional views of various ablation electrode configurations;

[0022] FIG. 20 depicts a seventh view of the ablation catheter of the catheter system of FIG. 1;

[0023] FIGS. 21 and 22 depict views of electrodes having coupling extensions that may be incorporated into the ablation catheter of the catheter system of FIG. 1;

[0024] FIG. 23 shows the ablation catheter of the catheter system of FIG. 1 without incorporation of the electrodes;

[0025] FIG. 24 shows the ablation catheter of the catheter system of FIG. 1 with incorporation of the electrodes;

[0026] FIG. 25 depicts a second example catheter system in a first configuration;

[0027] FIG. 26 depicts the second example catheter system in a second configuration;

[0028] FIG. 27 depicts a third example catheter system in a first configuration;

[0029] FIG. 28 depicts a fourth example catheter system in a first configuration;

[0030] FIG. 29 depicts the fourth example catheter system in a second configuration; and

[0031] FIGS. 30 and 31 schematically show example kits including aspects of the second, third, and/or fourth catheter systems.

DETAILED DESCRIPTION

[0032] The following description relates to a system of an electrically insulated electrodeguidewire and an ablation microcatheter, also referred to as an effector, and the method by which this system can be used to treat ventricular tachycardia (VT). The following description also relates to a guiding catheter system configured to deliver an effector configured to traverse the myocardium.

[0033] Some intramyocardial structural heart procedures use catheter-based cardiac devices, which may be navigated into a targeted position within the heart muscle via a freely steered guidewire. As one example, septal scoring along the midline endocardium (e.g., SESAME) is a transcatheter myotomy procedure that may be used to relieve or prevent a left ventricular outflow tract (LVOT) obstruction by splaying the circumferential myofibers of the septal myocardium with a flying-V laceration surface formed by an ensnared guidewire tip previously navigated through the interventricular septum. Another example intramyocardial procedure includes myocardial intramural remodeling by transvenous tether (MIRTH), which is a transcatheter ventricular remodeling procedure. Further, as described herein, an effector comprising an intramyocardial catheter and guidewire may be used to perform intramyocardial ablation.

[0034] The inventors herein have recognized that delivery of intramyocardial catheter and/or guidewire systems may be improved if such systems are delivered with a device that achieves temporary reversible but strong fixation into the myocardium that allows the intramyocardial catheter and/or guidewire system to be pushed hard into the myocardium.

[0035] In one example, a guiding catheter system for intramyocardial navigation and ablation is provided. The guiding catheter system includes an accessor catheter including a shaft, the shaft including one or more lumens, the one or more lumens sized to accommodate an effector configured to perform intramyocardial navigation and an anchor system.

[0036] In the examples presented herein, the guiding catheter system is explained as being configured to deliver an effector configured to treat ventricular tachycardia (VT). However, other effectors may be delivered with the guiding catheter system disclosed herein, such as microcatheters and/or guidewires for performing procedures such as SESAME, MIRTH, and the like. Intramyocardial navigation may create counter-force that displaces equipment and retards device advancement. Thus, the guiding catheter system disclosed herein provides counter-traction and device stability to facilitate advancement of guidewires and/or catheters within the myocardium.

[0037] As explained above, the effector delivered by the guiding catheter system may include an ablation catheter system for treating VT that comprises an electrically insulated electrodeguidewire and an ablation microcatheter, at least in some examples. The effector/ablation catheter system may hereafter be referred to as VINTAGE (Ventricular Intramyocardial Navigation for Tachycardia Ablation Guided by Electrograms). VT can originate from damaged or scarred tissue or areas of abnormal automaticity located within the ventricles of the heart that disrupt electrical function necessary for normal heart function. For example, regions of scar and slow conduction can form the substrate for reentrant conduction pathways underlying VT. Ablation of key scarred or damaged tissue targets with radio-frequency (RF) energy may block the transmission of pathological electrical signals thereby treating VT. Current systems of ablation have their own limitations. For example, endocardial monopolar ablation may have difficulty reaching deep targets whereas epicardial monopolar ablation is hindered by the presence of thick epicardial fat and the threat of injury to nearby coronary arteries.

[0038] Thus, the VINTAGE system disclosed herein addresses these issues via guidewire navigation to intramyocardial targets and ablation in the myocardium with an ablation electrode. As shown in FIGS. 1-2, the VINTAGE system may include an ablation microcatheter including an ablation electrode and one or more mapping/tracking electrodes, and configured for coaxial arrangement with a navigation guidewire. The ablation microcatheter may be sized to accommodate the navigation guidewire in a central lumen and may include a fenestrated or segmented ablation electrode to facilitate irrigation, via irrigant in the central lumen, during ablation.

[0039] As mentioned above, intramyocardial navigation creates counter-force that displaces equipment and retards device advancement. Thus, the VINTAGE system may be guided to the myocardium and supported while traversing the myocardium by the guiding catheter system. As shown in FIGS. 3-6, the guiding catheter system may include an accessor catheter coaxially arranged in an outer catheter, with the accessor catheter configured to deliver an anchor system and an effector (e.g., the VINTAGE system). The accessor catheter and/or outer catheter may be deflectable to control the angle of engagement with the myocardium, and the anchor system may include a myocardial engagement component configured to engage the myocardium and provide support while the VINTAGE system is deployed into the myocardium for ablation, as shown in FIGS. 7-11.

[0040] The ablation microcatheter and the navigation guidewire of the VINTAGE system may be used to traverse the myocardium to reach an ablation target, guided by electrograms detected from the electrodes on the ablation microcatheter and guidewire, or by position information encoded on electromagnetic fields generated by electroanatomic mapping systems. Irrigation with an electrolyte may be performed via the flush port and fenestrations/openings of the ablation microcatheter and ablation performed with the ablation electrode to alter the electrical and/or physicochemical characteristics of the target myocardial substrate. Aspects of the VINTAGE system, including the ablation microcatheter and the navigation guidewire and/or the accessor catheter, may be packaged in a kit, as shown in FIG. 12.

[0041] Turning now to the figures, FIG. 1 depicts an example of an effector in the form of an ablation catheter system 100 (also referred to as a VINTAGE system), in a first configuration. FIG. 1 (as well as FIGS. 2-10) includes a Cartesian coordinate system 199 to orient each view of the ablation catheter system 100 provided herein. In the example shown in FIG. 1, the y-axis may be a vertical axis (e.g., extending parallel to gravity with the positive y direction pointing in the direction of the arrow, away from ground), the x-axis of coordinate system 199 may be a longitudinal axis (e.g., horizontal axis), and/or the z-axis of coordinate system 199 may be a lateral axis, in one example. However, the axes may have other orientations, in other examples. When referencing direction, positive may refer to in the direction of the arrow of the x-axis, y-axis, and z-axis and negative may refer to in the opposite direction of the arrow of the x-axis, y-axis, and z- axis. An unfilled circle may represent an arrow and an axis facing away, or negative to, a view. However, it is to be appreciated that the ablation catheter system 100 may be held or used in any orientation without departing from the scope of this disclosure. Further, the term distal end may refer to a first end of the ablation catheter system 100 configured to be positioned within a heart of a patient and the term proximal end may refer to a second end of the ablation catheter system 100 configured to remain external to the patient. In some examples, the patient may be human, however in other examples the patient may be nonhuman.

[0042] The ablation catheter system 100 includes an ablation microcatheter 102 that includes a shaft 101 (e.g., a polymer tube) including a body 103 and a tapered nosecone 106. The ablation microcatheter 102 further includes a first mapping electrode 104 coupled to the shaft 101 at a distal end of the ablation microcatheter 102, a fenestrated, conductive ablation electrode 108 coupled to the shaft 101 at the distal end (e.g., proximal the first mapping electrode 104), and a second mapping electrode 109 coupled to the shaft 101 proximal the ablation electrode 108. The ablation microcatheter 102 may have a generally cylindrical shape with a hollow interior to facilitate a coaxial arrangement of a navigation guidewire 110. The shaft 101, and specifically the tapered nosecone 106, may terminate at a distal tip 105 that has an opening through which the navigation guidewire 110 may extend. At the distal tip, the ablation microcatheter 102 may have a first inner cross-sectional diameter (e.g., along the z axis) in a range of 0.014-0.018 inches. The tapered nosecone 106 may taper in width/cross-sectional area along the x axis (and specifically may taper in the negative x direction). Accordingly, at least in some examples, the ablation microcatheter 102 may have a larger cross-sectional area in the body 103 (e.g., proximal of the first mapping electrode 104) than at the distal tip 105. For example, the ablation microcatheter 102, along its entirety other than the tapered nosecone 106, may have a second inner cross-sectional diameter (e g., along the z axis) in a range of 0.021-0.035 inches and an outer cross-sectional diameter in a range of 0.025-0.038 inches. Each of the first mapping electrode 104 and the second mapping electrode 109 may be surface ring electrodes that extend radially around an entire circumference of the shaft 101 and have inner and outer diameters that match the inner and outer diameters of the ablation microcatheter mentioned above. However, other geometrical arrangements are possible without departing from the scope of this disclosure. For example, one or both of the first mapping electrode 104 and the second mapping electrode 109 may be semi-circular such that the electrode(s) extends radially around only half the circumference of the shaft 101. In the example illustrated in FIGS. 1 and 2, the first mapping electrode 104 may be positioned between the tapered nosecone 106 and the ablation electrode 108, though the first mapping electrode 104 may be positioned elsewhere on the ablation microcatheter 102 without departing from the scope of this disclosure. Further, in some examples, more than two mapping electrodes may be provided. The ablation microcatheter 102 may have a suitable length (e.g., along the x axis) to facilitate placement of the ablation microcatheter 102 in a patient and specifically to facilitate placement of the distal end of the ablation microcatheter 102 in a heart of the patient while the proximal end of the ablation microcatheter 102 remains external to the patient. The ablation microcatheter 102 may include an opening at the distal tip 105 to allow insertion and removal of the navigation guidewire 110 as well as an opening at the proximal end. At the proximal end, the ablation microcatheter 102 may include and/or be coupled to various hardware 112 to facilitate navigation of the ablation microcatheter 102 as well as fluid irrigation during an ablation procedure.

[0043] The hardware 112 may include an irrigation port 112a, electrode connectors, an RF connector, and a hemostatic valve. In some examples, the hemostatic valve may be integrated with the ablation microcatheter 102, or the hemostatic valve may be detachable and the ablation microcatheter 102 may include a connector (e.g., a Luer lock connector) to facilitate coupling of the hemostatic valve. The electrode connectors may be configured to couple to a signal processor, for example, via one or more first connections 118 (e.g., signal wires). The first mapping electrode 104 and the second mapping electrode 109 may be coupled to the electrode connectors via a suitable connection, such as wires extending along or within a wall forming the ablation microcatheter 102 (e.g., within the body 103). In some examples, the electrode connectors may include terminals of the wires that are accessible to the one or more first connections 118. In other examples, the electrode connectors may include external connector(s) configured to mate with a corresponding connection of the one or more first connections 118. Navigation of the ablation microcatheter 102 may be guided by x-ray fluoroscopy, electroanatomic mapping (EAM), and/or electrocardiographic radial depth navigation (EDEN), and/or intracardiac ultrasound. EDEN provides real-time, depth-specific unipolar intramyocardial electrogram patterns that indicate intramural radial position during microcatheter and guidewire navigation based on output from the first mapping electrode 104, the second mapping electrode 109, and/or an exposed conductor of the navigation guidewire, explained below. The RF connector may facilitate coupling to an RF generator 208, explained below.

[0044] Thus, the ablation microcatheter 102 includes one or more mapping electrodes allowing intramyocardial EAM and/or EDEN tracking and a fenestrated ablation electrode to allow RF ablation and irrigation during RF ablation. The ablation microcatheter 102 is capable of tracking over the navigation guidewire 110, is capable of intramyocardial pacing, is capable of deep intramyocardial positioning under x-ray, EAM, and EDEN guidance, is capable of RF ablation, and is capable of infusing electrolyte around the ablation electrode. The ablation microcatheter 102 includes electrode connectors for EAM and a connector for an RF generator for ablation. The ablation microcatheter 102 may be electrically insulated from the navigation guidewire and any surrounding catheters and media. The ablation microcatheter 102 may have a "short" rotating hemostatic valve/adaptor (e.g., of less than 2cm) and allows coaxial placement of the navigation guidewire 110 as well as a sidearm (e.g., the irrigation port 112a) to allow electrolyte infusion. The ablation microcatheter 102 may have a length of 135-175 cm.

[0045] The navigation guidewire 110 may comprise a thin (e.g., having an outer diameter in a range from 0.01 inches to 0.02 inches) cylindrical material having a stiffness (or flexibility) that enables insertion into and navigation within the myocardium. For example, the navigation guidewire 110 may comprise stainless steel and/or nickel -titanium alloy (e.g., Nitinol) and/or another suitable biocompatible alloy, and may have customized or variable stiffness and diameter along its length for increased pushability and kink resistance. Further, a length of the navigation guidewire 110 is electrically insulated except for an exposed conductor 111 at the distal end of the navigation guidewire 110 and a connection point at the proximal end of the navigation guidewire 110. For example, the navigation guidewire 110 may be coated with one or more insulators except for the exposed conductor 111 and the connection point that electrically couples the exposed conductor to an electrode connector 1 16 via the electrically conductive transmission line. In this way, the navigation guidewire 110 may include an insulated region and an uninsulated region (e.g., the exposed conductor 111). The electrode of the navigation guidewire (e g., the exposed conductor 111) may be a unipolar electrode in some examples. The electrode connector 116 may be coupled to the signal processor, for example, via a second connection 122 (e.g., a signal wire). The electrode connector 116 may be configured to limit the mechanical limitation on the operator torqueing the navigation guidewire during operation/advancement/retraction, to ensure tactile feedback and to minimize physical constraints on torque/advancement/withdrawal. The navigation guidewire 110 may have a tip stiffness (measured by lateral deflection at a fixed distance from the tip, such as 10mm) at the distal end of the navigation guidewire 110 ranging from 6 to 60 g, such as 20-40 g, allowing a short l-2mm x 30° "CTO" curve, as well as a straight tip (e.g., at the proximal end), each with electrical insulation to allow EDEN and EAM tracking. The navigation guidewire 110 may include radiopaque markers allowing fluoroscopic tracking. The distal tip of the navigation guidewire 110 has an insulation-free segment ~lmm in length, for EAM/EDEN; the proximal tip of the navigation guidewire 110 has an insulation-free segment ~10mm in length, for attachment to an electrode connector 116 to allow EAM/EDEN. The length of the navigation guidewire 110 may be 200-300cm, in some examples. In some examples, the electrode connector 116 may be detachable.

[0046] Thus, the ablation catheter system 100 in the first configuration includes a coaxial arrangement of the ablation microcatheter 102 and the navigation guidewire 110, with the navigation guidewire 110 accommodated within the ablation microcatheter 102. During an ablation procedure, the ablation catheter system 100 may be navigated to the heart (e.g., via a guiding catheter system disclosed herein) and advanced into the myocardium, to any target within the wall of the left ventricle, for example. Navigation of the ablation catheter system 100 may be guided by x-ray fluoroscopy, EAM, EDEN, and/or intracardiac echocardiography (ICE). Additional details about navigating the ablation catheter system 100 are provided below.

[0047] Once the ablation microcatheter 102 reaches the target, ablation of the target may be performed via the ablation electrode 108. The relatively large diameter of the ablation microcatheter 102 (and the irrigation port 112a) relative to the relatively small diameter of the navigation guidewire 110, as well as fenestrations of the ablation electrode 108, may facilitate irrigation of the target with an electrolyte prior to and during ablation. The irrigation may be facilitated by an irrigation pump 206 fluidly coupled to the irrigation port 112a. When the irrigation pump 206 is coupled to the irrigation port 112a and the irrigation pump 206 is activated, the electrolyte may be pumped through the interior of the ablation microcatheter 102 and out of the fenestrations of the ablation electrode 108. The irrigation pump 206 may be capable of infusing intramyocardial ionic irrigant (such as 0.9% (normal) or 0.45% (half-normal) saline solution). In some examples, the irrigation pump 206 may include timing and gating circuitry to automate initiation of infusion/infiltration/irrigation approximately 1 minute before initiation of RF ablation, and continuing at approximately the same rate for the duration of the RF ablation. The irrigant may also be a caustic agent intended to effect adjunctive chemoablation, using agents such as alcohols or short-chain carboxylic acid such as acetic acid.

[0048] Ablation may be achieved via the RF generator 208 coupled to the ablation microcatheter 102, which may be activated to deliver RF energy to the target via the ablation electrode 108. The RF generator 208 may be capable of generating kilohertz AC radiofrequency waves ranging 10-100 W intended to achieve permanent thermal tissue injury. The RF generator 208 may include real-time impedance monitoring, a dispersive electrode, and attendant safety circuitry. In other examples, the RF generator 208 may include microsecond or nanosecond RF pulse trains intended to achieve non-thermal permanent tissue injury, sometimes described as "pulsed field ablation." Some examples may allow automatic modulation and cessation of energy based on pre-specified changes in impedance.

[0049] FIG. 2 shows a magnified view of the distal end of the ablation microcatheter 102 in the first configuration (e.g., with coaxial arrangement with the navigation guidewire), showing the distal tip 105, tapered nosecone 106, first mapping electrode 104, ablation electrode 108, second mapping electrode 109, and body 103. The first mapping electrode 104 may have a length along the x axis of 1-2 mm. The first mapping electrode 104 may be separated from the tapered nosecone 106 by a first insulating segment 202 (e.g., a first section of the polymer tube) and from the ablation electrode 108 by a second insulating segment 204 (e.g., a second section of the polymer tube). The ablation electrode 108 may be comprised of a hollow, circular segment of metal that has a length along the x axis of 10-15 mm. The ablation electrode 108 include a plurality of fenestrations (e.g., apertures), such as first fenestration 128, that extend through the metal of the ablation electrode. The number, size, shape, and placement of the fenestrations may be non-limiting and may be selected based on a desired irrigation rate, position of the target, and other considerations. As shown, the fenestrations may be circular and of equal diameter (e.g., 0.5-1 mm). The fenestrations may be arranged around the ablation electrode 108 in an even, repeating pattern. For example, the fenestrations may be arranged into a plurality of rows that extend longitudinally (e.g., along the x axis). Each row may include the same number of longitudinally-aligned, evenly-spaced fenestrations (e.g., six). The rows may be axially offset from each other in an alternating pattern. For example, a first row may be axially offset relative to a second row, such that a first fenestration of the first row (e.g., the first fenestration 128) is closer to a distal edge of the ablation electrode 108 than a first fenestration of the second row (e.g., second fenestration 129). As such, the fenestrations are distributed into a plurality of radial groups that are longitudinally offset in an alternating pattern. For example, the first fenestration 128 may be included in a first radial group of circumferentially-aligned fenestrations that are evenly spaced around the circumference of the ablation electrode 108. The second fenestration 129 may be included in a second radial group of circumferentially-aligned fenestrations that are evenly spaced around the circumference of the ablation electrode 108. Due to the offset pattern of the rows of fenestrations, the first fenestration 128 is not longitudinally-aligned with any fenestrations in the second radial group, but is instead longitudinally-aligned with a fenestration in a third radial group, a fifth radial group, etc. As such, the ablation electrode 108 may include a portion of metal between each pair of adjacent, longitudinally-aligned fenestrations and between each pair of adjacent, circumferentially-aligned fenestrations. The fenestrations may be distanced from each terminal edge of the ablation electrode by a suitable amount, such as 0.5-1 mm.

[0050] However, other configurations are possible, such as non-circular (e.g., rectangular) fenestrations, fenestrations of varying diameter and/or shape, and/or an uneven pattern of fenestrations. For example, the fenestrations may be distributed such that more fenestrations (or all of the fenestrations) are located on one side of the ablation electrode 108 to facilitate directed, asymmetrical irrigation. In some examples, the body 103 may include longitudinal grooves inside the inner lumen (e.g., on an inner surface of the body 103/polymer tube) to enhance irrigation fluid delivery. Thus, the ablation electrode may include one or more openings to facilitate irrigation during ablation. The one or more openings may be static (e.g., fixed in size and position) or dynamic (e.g., the size of each opening may be adjustable and/or the one or openings may be exposed upon actuation of a particular component) and may be of any suitable shape, including but not limited to circular, semi-circular, oval, rectangular, spiral, helical, sinusoidal, clamshell, and the like. [0051] The second mapping electrode 109 may have the same length as the first mapping electrode 104 (e.g., a length along the x axis of 1-2 mm). The second mapping electrode 109 may be separated from the ablation electrode 108 by a third insulating segment 205 (e.g., a third section ofthe polymer tube). The tapered nosecone 106, first insulating segment 202, the second insulating segment 204, the third insulating segment 205, and the body 103 may collectively form the shaft 101 (e.g., the polymer tube).

[0052] The first insulating segment 202, the first mapping electrode 104, the second insulating segment 204, the ablation electrode 108, the third insulating segment 205, the second mapping electrode 109, and the body 103 may all be circular and hollow with the same or substantially similar (e.g., within 5-10%) inner diameter, to thereby create an inner lumen that extends from the proximal/hub end of the body 103 (shown in FIG. 4 and described in more detail below) to the tapered nosecone 106. Further, the tapered nosecone 106, the first insulating segment 202, the second insulating segment 204, the third insulating segment 205, and the body 103 may be comprised of the same material (e.g., polymer), at least in some examples. Likewise, the first mapping electrode 104, the ablation electrode 108, and the second mapping electrode 109 may all be comprised of the same material, such as platinum-iridium alloy, stainless steel alloy, titanium, gold-plate, etc. In some examples, molybdenum-rhenium may be used to allow a lower profile. In some examples, the mapping electrodes may be partial ring electrodes, spiral electrodes (e.g., coils), strip electrodes, or have another suitable configuration. In still further examples, the shaft 101 may extend along the ablation electrode to form a lining on an inner surface of the ablation electrode. In such examples, the lining may include openings that match the openings of the ablation electrode.

[0053] The navigation guidewire 110 can be seen within the inner lumen of the ablation microcatheter 102 via the fenestrations of the ablation electrode 108. The size mismatch between the navigation guidewire 110 (e.g., diameter of 0. 1-0.2 inches, such as 0.014 inches) and central lumen (e.g., diameter of 0.021-0.035 inches) may allow irrigant to be accommodated in the central lumen and be expelled out of the fenestrations of the ablation electrode 108 during ablation. The navigation guidewire 110 may extend out of the distal tip 105. Due to the tapering of the tapered nosecone 106, the size mismatch between the navigation guidewire 110 and the distal tip 105 may be relatively small, which may allow the ablation microcatheter 102 to slide over the navigation guidewire 110 but prevent flow of irrigant out of the distal tip 105. [0054] FIG. 3 shows a view of a guiding catheter system 300 arranged with the ablation catheter system 100. The guiding catheter system includes an outer catheter 302, an accessor catheter 304, and an anchor system including an anchor shaft 306. To facilitate delivery of the ablation catheter system 100, the accessor catheter 304 may be coaxially arranged in the outer catheter 302, and the anchor shaft 306 may be arranged in the accessor catheter 304 along with the ablation microcatheter 102 and navigation guidewire 110 of the ablation catheter system 100. The guiding catheter system 300 may be flexible and deflectable, with each of the outer catheter 302, the accessor catheter 304, and the anchor shaft 306 being comprised of or including regions of flexible and/or deflectable material.

[0055] The outer catheter 302 may have a cylindrical shape with a hollow interior to slidingly receive the accessor catheter 304. The outer catheter 302 may have an outer diameter in a range of 2.6-2.8mm (e.g., 8-8.5 F; 0.10-0.11 inches), a usable length in a range of 100-130 cm, and an opening at the distal end though which the accessor catheter 304 is configured to extend. In some examples, the outer catheter 302 may include a distal deflectable portion with a variable radius of deflection (e.g., of 2-5 cm) and a deflection angle of 0-135 degrees.

[0056] The accessor catheter 304 may have a cylindrical shape with at least one hollow lumen to slidingly receive the anchor shaft 306 and/or the ablation microcatheter 102. In some examples, the accessor catheter 304 may have two hollow, non-concentric lumens, one to accommodate the anchor shaft 306 and another to accommodate the ablation microcatheter 102. In other examples, the accessor catheter 304 may have one lumen to accommodate both the anchor shaft 306 and the ablation microcatheter 102.

[0057] In the example shown herein, the accessor catheter 304 may have an outer diameter of 1.95-2.75mm (e.g., 6-8.3 F; 0.07-0.107 inches), a usable length of 110-135 cm, and two openings at each of the proximal and the distal ends to provide access to the two hollow lumens. In some examples, the accessor catheter 304 may have deflectable capabilities with a distal deflectable portion that has a radius of deflection (e.g., of 2-5 cm) and deflection angle 0-135 degrees. In still further examples, the accessor catheter 304 may have a fixed, 90-degree distal deflection. The accessor catheter 304 may include at least one distal electrode for EAM and/or EDEN. For example, the accessor catheter 304 may include a first electrode 308 at the distal tip of the accessor catheter 304 and a second electrode 310 spaced apart from the first electrode 308 by a suitable amount (e.g., 2-5 mm). Each of the first electrode 308 and the second electrode 310 may be similar to the mapping electrodes of the ablation microcatheter 102, e.g., surface ring electrodes with a length of l-2mm. However, other electrode configurations are possible, such as spiral electrodes, strip electrodes, partial ring electrodes, etc. Further, in some examples, one or both of the first electrode 308 and the second electrode 310 may be omitted.

[0058] The anchor shaft 306 may comprise a thin (e.g., having an outer diameter in a range from 0.01 inches to 0.02 inches) cylindrical material terminating at myocardial engagement component 312 at a distal end of the anchor shaft 306. In the illustrated example, the myocardial engagement component 312 may include a set of prongs, such as two or more sharp prongs (e.g., three, as shown) each having a length of approximately 10- 15mm and appropriate curvature to form fish-hook shaped prongs when deployed. The set of anchor prongs may be configured to retract and deploy, such that the set of anchor prongs may be held along/in alignment with the anchor shaft 306 during navigation of the guiding catheter system 300 to the myocardium and then deployed to the position shown in FIG. 3 in order to engage the myocardium and anchor the guiding catheter system 300. However, other types of myocardial engagement components are possible, such as a corkscrew/helix with fixed or variable pitch and/or diameter. The anchor shaft 306 and the myocardial engagement component 312 may be comprised of a material that has a stiffness that enables insertion into the myocardium with sufficient flexibility to allow deflection of the anchor shaft 306 and retraction of the myocardial engagement component 312, such as stainless steel and/or nickel -titanium alloy (e.g., Nitinol) and/or another suitable biocompatible alloy, and may have customized or variable stiffness and diameter along its length for increased pushability and kink resistance.

[0059] Further, the anchor system may include a flexible hinge mechanism 314 that allows the accessor catheter 304 to be torqued, angled, and/or pivoted as desired without displacing the anchor shaft 306. The hinge mechanism 314 is located at the proximal end of the myocardial engagement component 312 and distal end of the anchor shaft 306. The hinge mechanism 314 may comprise two semi-loops passing through each other, one permanently and rigidly connected to the anchor shaft 306, and the other one permanently and rigidly connected to the proximal end of the myocardial engagement component 312. In another example, the hinge mechanism 314 may comprise a spring, with one end of the spring permanently attached to the proximal end of the myocardial engagement component 312 and the other end tensioned around and permanently attached to the distal end of the anchor shaft 306. In a still further example, the hinge mechanism 314 may comprise a permanent attachment between the myocardial engagement component 312 and the anchor shaft 306, mechanically reducing the outer diameter of the joint section to allow mechanical flexibility for deflection. All of the above examples of the hinge mechanism 314 provide torquability and pushability while the myocardial engagement component 312 is contained within the accessor catheter 304, and flexibility and deflection while the myocardial engagement component 312 is deployed.

[0060] In some examples, the anchor system (comprising the anchor shaft 306, hinge mechanism 314, and myocardial engagement component 312) may be separate from the accessor catheter 304, such that the anchor system can be inserted and removed from the accessor catheter 304 (e.g., for an “over-the-wire” configuration)., such as via a side port. In other examples, the anchor system may be integrated with the accessor catheter 304 (e.g., unable to be fully removed from the accessor catheter 304) but still configured to move relative to the accessor catheter 304 along the x axis. The anchor system may have a length of 115-140 cm when the anchor system is not removable from the accessor catheter 304. The anchor system may have a length of 280-330 cm when the anchor system is removable from the accessor catheter 304.

[0061] FIG. 4 schematically shows the proximal/hub end of the ablation microcatheter 102 and navigation guidewire 110 as well as the hub end of the guiding catheter system 300. The ablation microcatheter 102 may terminate at a hub, which may include or be the hardware 112 of FIG. 1. The hardware 112 may facilitate coupling between elements of the ablation microcatheter 102 and electrode connectors and an RF connector, as explained above with respect to FIG. 1. In FIG. 4, the hardware 112 is coupled to an RF connector 422, a positive electrode connector 424, and a negative electrode connector 426. It is to be appreciated that the ablation electrode 108 may be electrically coupled to the RF connector 422, and each of the first mapping electrode 104 and second mapping electrode 109 may be separately connected to each of the positive electrode connector 424 and negative electrode connector 426. The hub of the ablation microcatheter 102 may include an opening through which the navigation guidewire 110 extends. While not shown, the hardware 112 may further include a port for connecting to an irrigation pump, as explained above.

[0062] The guiding catheter system 300 includes a handle 400 at the proximal end. The handle 400 may include a body 401 with a first actuator 402 and a second actuator 404 for controlling the deflection angle and the pivot point location, respectively, of the outer catheter 302 and accessor catheter 304. In the example shown, the first actuator 402 may be a rotator knob and the second actuator 404 may be a slider knob, but other configurations are possible. The handle 400 further includes two entry lumens and one exit lumen for accommodating the anchor shaft 306 and the ablation microcatheter 102 (coaxially arranged with the navigation guidewire 110) and merging of the anchor shaft 306 and ablation microcatheter 102 into the accessor catheter 304. The two entry lumens may include a first entry lumen 406 configured to accommodate the ablation microcatheter 102 and a second entry lumen 408 configured to accommodate the anchor shaft 306. As shown, the anchor shaft 306 may terminate at the proximal end at a pusher 410 that may be moved along the x axis to move the anchor shaft 306 and deploy or retract the myocardial engagement component 312. The exit lumen 409 is present at the distal end of the handle 400. The outer catheter 302 extends outward from the distal end of the handle 400 and the accessor catheter 304 extends out of the handle 400 via the exit lumen 409, which is shown in FIG. 5 and explained in more detail below.

[0063] While not shown in FIG. 4, in some examples, the handle 400 may facilitate connection between the electrodes of the accessor catheter 304 and electrode connectors, similar to the hardware 112 and electrode connectors of the ablation catheter system, in order to connect the electrodes of the accessor catheter 304 to a signal processor. Further, in some examples, the myocardial engagement component 312 may be configured as electrodes for EAM and/or EDEN and the handle 400 may facilitate electrical connection between the myocardial engagement component and the signal processor. When the myocardial engagement component 312 is configured as an electrode(s) for EAM and/ EDEN, the myocardial engagement component 312 may include one or more electrodes at one or more tips of the myocardial engagement component and/or one or more electrodes at mid-shaft of the myocardial engagement component (e.g., midshaft of one or more prongs or mid-shaft of the helix/corkscrew, depending on the configuration of the myocardial engagement component). For example, the myocardial engagement component may be insulated except at one or more regions (e.g., each prong may be insulated except at its tip or a mid-shaft portion).

[0064] FIG. 5 is a partially-transparent view of the handle 400 to enable visualization of the components in the interior of the handle 400. In the example shown in FIG. 5, the accessor catheter 304 extends through the interior of the handle 400, though and/or in proximity to the first actuator 402 and the second actuator 404, while the outer catheter 302 terminates at the handle 400. However, it is to be appreciated that the outer catheter 302 may extend into the handle 400 a suitable amount. The first actuator 402 may control the deflection angle of the outer catheter 302 and the second actuator 404 may control linear movement of the accessor catheter 304. By moving the accessor catheter 304 linearly within the outer catheter 302, the pivot point of the accessor catheter 304 may be adjusted.

[0065] Toward the proximal end of the handle 400, the accessor catheter 304 may terminate, and the anchor shaft 306 and ablation microcatheter 102 may extend from the second entry lumen 408 and the first entry lumen 406, respectively, to the terminating end of the accessor catheter 304, where the anchor shaft 306 and the ablation microcatheter 102 may enter respective lumens of the accessor catheter 304. For example, as shown in FIG. 6, the accessor catheter 304 may have a terminating end 305 that includes two openings, with the anchor shaft 306 extending through a first opening of the two openings and the ablation microcatheter 102 extending through a second opening of the two openings. The first opening (and associated first lumen in the accessor catheter 304) may be larger than the outer diameter of the anchor shaft 306, which may allow for the myocardial engagement component 312 to fit inside the first lumen when in the retracted position. In some examples, the outer catheter 302 may not be coupled to the handle 400, but instead may be a separate deflectable catheter.

[0066] FIGS. 7-10 schematically show the flexible guiding catheter system 300 and ablation catheter system 100 positioned in a heart 700 of a patient in order to perform myocardial ablation. A portion of the heart 700 is shown in FIGS. 7-10, including a right ventricle 702 and a left ventricle 704 separated by myocardium (e.g., septum 706). FIG. 7 shows a zoomed-out perspective view in order to visualize both the distal ends and the proximal/hub ends of the guiding catheter system 300 and ablation catheter system 100. FIGS. 8A and 8B show a front view of the portion of the heart 700 and the guiding catheter system 300 and ablation catheter system 100. FIGS. 9 and 10 show zoomed-in perspective views of the portion of the heart 700 and the guiding catheter system 300 and ablation catheter system 100. It is to be appreciated that the handle 400 and hardware 112 may remain outside the patient and that the anatomy surrounding the heart and providing access to the heart (e.g., the femoral vein) are not depicted in FIGS. 7-10 to enable visualization of certain aspects of the guiding catheter system 300 and ablation catheter system 100, such as the length of the outer catheter 302, that would otherwise be obscured. [0067] As appreciated from FIG. 7, the distal ends of the guiding catheter system 300 and ablation catheter system 100 may be navigated to the right ventricle 702 (e.g., into the right ventricular cavity), with the outer catheter 302 (and coaxially-arranged accessor catheter 304 accommodating the anchor shaft 306, ablation microcatheter 102, and navigation guidewire 110) extending from the handle 400 to the heart 700 substantially along the x axis. However, the desired entry point into the myocardium in the example shown is the septum 706. Accordingly, a deflectable portion of the accessor catheter 304 or outer catheter 302 is adjusted (e.g., via the actuators on the handle 400) to form an approximately 90-degree bend at the distal end of the accessor catheter 304, in order to position a final, distal segment of the accessor catheter 304 and associated components so that the distal segment extends substantially parallel to the y axis.

[0068] When the tip of the accessor catheter 304 is positioned along the myocardium at the desired entry point, the anchor shaft 306 may be extended relative to the accessor catheter 304 to embed the myocardial engagement component 312 within the myocardium, as shown in FIG. 8 A. Once the anchor system is anchored at the desired location via the myocardial engagement component 312, the navigation guidewire 110 may be advanced into the myocardium and the ablation microcatheter 102 may track over the navigation guidewire 110, as shown in FIGS. 8A and 8B. The position of the navigation guidewire 110 and ablation microcatheter 102 may be tracked using EAM, EDEN, fluoroscopy, and/or ICE. Once it is confirmed that the ablation microcatheter 102 is positioned at the ablation target, ablation may be performed via the ablation electrode (including irrigation of the ablation target to create and ablation field). It is to be appreciated that the navigation guidewire 110 may include a CTO-tip to allow the navigation guidewire 110, and hence ablation microcatheter 102, to be steered and advanced in a desired manner through the myocardium to allow for the curved trajectory shown in FIGS. 8A and 8B.

[0069] FIGS. 9 and 10 show examples of deflection occurring via the outer catheter 302 and pivot point adjustment occurring via the accessor catheter 304. The outer catheter 302 has a constant length, a fixed pivot point, and an adjustable deflection radius. As shown in FIG. 9, the outer catheter 302 may include a deflectable portion 902 at the distal end of the outer catheter 302 that can be adjusted via the actuators of the handle 400 to change the deflection radius and/or deflection angle. For example, movement of the first actuator 402 to rotate the first actuator 402 clockwise or counter-clockwise may result in movement of a pull wire coupled to the deflectable portion 902 back toward the rear/proximal end of the handle 400. Movement of the pull wire may cause the deflectable portion 902 to bend with a desired radius of curvature, as shown. The accessor catheter 304 has a fixed length but is connected to second actuator 404 of the handle 400 so that the accessor catheter 304 can be moved linearly within the outer catheter 302. The second actuator 404 may be used to linearly move the accessor catheter 304 within the outer catheter 32 to change the pivot point of the accessor catheter 304, such that the distal tip of the accessor catheter 304 is positioned at a desired point along the z axis. FIG. 10 shows that the accessor catheter 304 has an adjustable extension length out of the outer catheter 302 to allow adjustment of the pivot point of the accessor catheter 304.

[0070] The electrodes of the ablation microcatheter 102 shown in FIG. 2 as well as the electrodes of the accessor catheter 304 shown in FIG. 3 may be ring electrodes; however, other mapping electrode configurations are possible, such as partial rings that extend only partially around the respective shaft, strips, coils, etc. Further, the ring electrodes shown herein may have straight/flat edges that may be mounted on the ablation microcatheter 102 or accessor catheter 304 by bonding the edges of the electrodes to the material of the respective shaft using glue, heat, and/or other mechanisms, such as embedding the electrodes in the shaft by reflowing or extruding the shaft material segments before and after the electrodes. However, the straight edges of the electrodes may not adhere to the elements of the ablation microcatheter or accessor catheter as reliably as desired for all applications and may be prone to dislodging. Thus, one or more of the electrodes may include helical, feathered, dentate, and/or tapered extensions at the edges that allow enhanced bonding to the polymer components of the ablation microcatheter or accessor catheter and provide smoother mechanical transition from the polymer catheter shaft to the metal electrode body, as shown in FIGS. 21-24 and described in more detail below. The helical, feathered, dentate, and/or tapered extensions may be configured to be partially or fully embedded in the polymer segments of the ablation microcatheter and/or accessor catheter distal and proximal the electrodes. [0071] Thus, an effector deliverable by an accessor is described herein. The effector may be configured to be navigated to a target within the myocardium and perform ablation within the myocardium. In the example disclosed herein, the effector may be the ablation catheter system described herein, which provides for coaxial arrangement of a 0.014" traversal and navigation guidewire (e.g., the navigation guidewire 110) and an -0.025" (typically 0.021-0.035") compatible tracking/infusion/ablation microcatheter (e g., ablation microcatheter 102) with one or more mapping electrodes (e g., the first mapping electrode 104 and the second mapping electrode 109) and a fenestrated/ segmented ablation electrode (e.g., ablation electrode 108) having one or more openings. The ablation microcatheter may be low-profile, have a lumen for flowing irrigant and that tapers at a distal end to closely match the guidewire to deliver in coaxial fashion and to mitigate "size step-up" as the microcatheter is advanced over the coaxial guidewire, and have a braided metallic wire skeleton surrounded by electrically insulating and often lubricious polymer materials. Blood contacting surfaces of the microcatheter may be biocompatible. Polymers and/or markers of the microcatheter may be radiopaque to impart fluoroscopic conspicuity. The ablation microcatheter may incorporate electrical transmission lines that convey biopotentials, current, ablative energy, or other electromagnetic signals to achieve ablation, biopotential measurement, and/or and electroanatomic tracking of the transmission line termini (e.g., the electrodes). The transmission lines may have shaped cross-sections. In particular, when a lining is provided that lines the ablation electrode, the electrical transmission lines may extend in the lining to electrically connect to elements distal of the ablation electrode (e.g., the first mapping electrode). In some examples, the polymer tube may include embedded metallic or non-metallic braiding or coils that are continuous or segmented to alter the mechanical performance of the ablation microcatheter. These braids or coils may include individually insulated metals that can serve as the transmission lines. The electrodes of the ablation microcatheter may be short (1 -2mm) for tracking or longer (5- 10mm) for tracking and RF ablation. The ablation microcatheter may incorporate coils or braids to impart trackability and pushability and preservation of lumen dimensions during advancement along tortuous trajectories. The ablation microcatheter disclosed herein thereby incorporates irrigation opening(s) in an over-the-wire implementation, with an ablation electrode for intramyocardial ablation, tracking/mapping micro-coils/electrodes for E-field and B-field (electroanatomic) tracking, with a tapered nosecone configuration to allow delivery into the muscle of the beating heart.

[0072] The accessor may be included as part of the guiding catheter system described herein. The accessor (e.g., accessor catheter 304) may be configured to fit through a right ventricular angled delivery/guiding sheath (from the femoral vein to the right atrium makes a right angle into the right ventricle). The accessor may have one of three curve options to achieve orthogonal contact with the interventricular septum on the right ventricular side. The first option may be that the accessor has a fixed, 90-degree curve. The second option is that the accessor is deflectable from 0-135 degrees (or more) and has a variable radius of curvature. The third option is that the accessor may be a straight, flexible catheter contained within, and operated in combination with, a deflectable catheter having a deflection angle of 0-135 degrees and having a variable radius of curvature. The large radii allow the effector to rest against the right ventricular free wall to provide extra “backup support” while advancing equipment through the interventricular septum. The guiding catheter system may further include a deployable anchor system (e.g., the anchor shaft 306, myocardial engagement component 312, and hinge mechanism 314). The deployable anchor system may have a deployable myocardial engagement component, such as a set of anchor prongs having two or more sharp prongs that are configured to expand outward to engage the myocardium and prevent dislodgement. The anchor system may have a flexible hinge point mechanism that allows the accessor to be torqued, angled, and/or pivoted as desired to change the accessor endhole (e.g., the distal end of the accessor) entry angle without displacing the anchor shaft or changing the selected entry point. Once deployed, the anchor system allows the accessor tip contact position (where the distal end of the accessor contacts the myocardium) to be fixed. The anchor system may have an entry angle between 0 and 75-90 degrees relative to/orthogonal to the septal surface, and the myocardial engagement component (e.g., anchor prongs) may each extend until they are orthogonal to the accessor, typically 45-135 degrees. The guiding catheter system may include a mechanism to retrieve the anchor (e.g., the pusher) and the anchor system may optionally be configured with electrodes so that electrograms can be sampled from the anchor system as evidence of good contact.

[0073] The guiding catheter system may include a hub (e.g., handle 400) that controls the insertion/retraction of the anchor system, controls the deflection of the outer catheter, and controls the linear extension of the accessor. The hub may include or allow a hemostatic adapter valve for devices inserted/delivered through and into its endhole, and may include an optional side-hole for flushing.

[0074] The accessor may include non-concentric (e.g., side-by-side) accessor lumens to accommodate the anchor system and the effector. The accessor has an endhole through the second lumen to deliver the effector, appose it to the contact point, and provide backup support during advancement of the effector and accompanying navigation guidewire. The accessor may include one or more EAM tracking rings/coils (e.g., electrodes) to indicate position and orientation, including accompanying conductors and connectors. Optionally, the accessor may include radiopaque markers and/or enhanced ultrasound reflectance at least of the distal tip. The outer catheter may also include radiopaque markers to indicate the tip of the outer catheter.

[0075] It is to be appreciated that the effector may take on a different form than the ablation microcatheter disclosed herein. For example, rather than including fenestrations or other openings in the ablation electrode to facilitate irrigation, the ablation electrode may be continuous and lack apertures, and irrigation may occur due to the size mismatch between the navigation guidewire and the ablation microcatheter. In such examples, the ablation microcatheter may have a larger outer diameter (particularly at the distal tip) than the ablation microcatheter disclosed herein. As such, at least in some examples, the effector may include a dilator to facilitate embedding within the myocardium and/or may include a separate microcatheter to deliver the ablation microcatheter. [0076] The ablation catheter system 100 (or the catheter system 2500, the catheter system 2700, or the catheter system 2800, which will be described in more detail below) and guiding catheter system 300 may be used to perform intramyocardial ablation according to the method 1100 of FIG. 11.

[0077] At 1102, method 1100 includes positioning and aiming the accessor (e.g., accessor catheter 304) and effector (e.g., ablation microcatheter 102, or the catheter system 2500, the catheter system 2700, or the catheter system 2800) to the right ventricle using a curved or deflectable guiding sheath from a percutaneous venous access, such as the femoral vein into the right atrium, to the right ventricular septal endocardium (e.g., the endocardial surface of the septum). At 1104, the septum is engaged with the accessor, with the angle of engagement controlled if needed. To engage the septum with the accessor, the accessor or a fixed-curve or deflectable catheter (e.g., the outer catheter 302) may be adjusted to adjust a radius of curvature of the accessor to allow the distal end of the accessor to be positioned orthogonal to the septum. Further, if desired, the deflection angle may be adjusted to position the accessor at a desired entry point on the septum and/or at a desired entry angle. At 1106, the location of the accessor may be tracked and confirmed using EAM and/or EDEN based on signals obtained from the electrode(s) of the accessor and/or via fluoroscopy and/or intracardiac echocardiography.

[0078] Once the accessor is confirmed to be positioned at the interventricular septum, at a desired entry point and desired entry angle, the myocardial engagement component (e.g., the myocardial engagement component 312) of the anchor system may be inserted from the accessor into the myocardium, as indicated at 1108, and entry into the myocardium confirmed using EDEN unipolar electrogram morphology and classification. At 1110, method 1100 may include entering the myocardium with the navigation guidewire of the ablation catheter system, and at 1112, method 1100 includes entering and navigating the myocardium with the VINTAGE coaxial catheter- wire system (e.g., the ablation catheter system 100, the catheter system 2500, the catheter system 2700, or the catheter system 2800) using EDEN, EAM, fluoroscopy, and/or ultrasound. The ablation microcatheter and the navigation guidewire inside of the ablation microcatheter are delivered to the right ventricular septal endocardium via the accessor. The navigation guidewire is extended from this system to engage the myocardium. Electrosurgical radiofrequency energy may be used to traverse the endocardial border if needed. The ablation catheter system (e.g., the navigation guidewire 110 and the ablation microcatheter 102, or the ablation catheter systems described below, including the catheter system 2500, the catheter system 2700, and the catheter system 2800) is advanced to the deep intramyocardial ablation target. At 1114, mapping and pacemapping may be performed as desired to localize the VT circuit to identify the ablation target. Thus, components of the system may be used for determining functional characteristics of the target and nearby myocardium, for electroanatomic mapping of native and induced cardiac rhythms, and for ventricular stimulatory pulses to achieve pace-mapping of the target myocardium as appropriate. Multiple electrodes on the ablation microcatheter and navigation guidewire may be combined as desired for multipolar mapping.

[0079] At 1116, deep intramyocardial irrigation is performed. Once the ablation electrode (e.g., on the ablation microcatheter) is at the target, pre-irrigation is performed (e.g., with irrigant supplied via the lumen of the ablation microcatheter), typically with saline solution (0.45% - 0.9%), of the target ablation field via the fenestrations of the fenestrated ablation electrode of the ablation microcatheter, embedded deep in the myocardium adjoining the target, beginning approximately one minute before RF ablation is instituted, at a suitable rate, such as a rate of ~2mL/min, and continuing at the same rate until RF ablation is terminated.

[0080] At 1118, method 1100 includes performing ablation including during irrigation. The ablation electrode (e.g., of the ablation microcatheter) is used to apply RF energy to the target myocardium, typically/optionally continuously guided by real-time impedance monitoring. In some examples, the following empirically derived target thresholds may be applied for the RF energy application and real-time impedance monitoring: expected drop from irrigation 5 to 25 ohms; expected drop from heating 10 to 15 ohms; expected threshold increase heralding steam pop: 18 ohms. Ranges of RF energy include 10 to 50 W. RF energy may be altered during ablation based on the above-mentioned empirical parameters.

[0081] The ablation microcatheter may be repositioned and the mapping and ablation procedures repeated as needed, as indicated at 1120 of method 1100. At the conclusion of the procedure, the devices (e.g., the ablation microcatheter, the navigation guidewire, the anchor system myocardial engagement component) are removed from the myocardium, accessor and outer catheter withdrawn, hemostasis achieved, and the procedure concluded.

[0082] Thus, the VINTAGE system disclosed herein (e.g., the ablation catheter system 100, or the catheter system 2500, the catheter system 2700, or the catheter system 2800 described below) allows access to deep myocardial targets that are inaccessible for ablation from the endocardial and epicardial surfaces, including the deep septum, LV summit, and papillary muscles. The guiding catheter system disclosed herein (e.g., the guiding catheter system 300) may facilitate placement of the VINTAGE system at the endocardial border of the myocardium at a desired location and angle using an accessor housing the VINTAGE system that can be deflected directly or via a deflectable outer catheter. The guiding catheter system can provide backup support during intramyocardial entry and navigation using a deployable anchor system (e.g., that is deployed from the accessor) that has a flexible junction to allow the anchored accessor to change its entry position and angle to be varied interactively, a myocardial engagement component in its deployed position (e g., the anchor prongs), and a retrieval mechanism upon procedure completion. The backup support may be further provided via variable radius of curvature of the accessor, which may allow the accessor distal tip to appose the contralateral endocameral wall during the procedure.

[0083] Some components of the VINTAGE system and the guiding catheter system (e.g., the ablation microcatheter, the navigation guidewire, and/or accessor) may include one or more electrodes to enable EAM (e.g., navigation may be provided via electromagnetic fields encoding geometric position and time from an electroanatomic mapping system detected by one or more electrodes positioned on the navigation guidewire and/or the ablation microcatheter and/or on the accessor) in order to identify targets for ablation as well as enable EDEN to guide desired positioning of the components in the myocardium. In particular, real-time imaging techniques such as x-ray fluoroscopy or ultrasound may provide information regarding a longitudinal (e.g., base- to-apex) position and a circumferential (e.g., “clock-face”) position of the various components of the VINTAGE and guiding systems in the heart, these techniques lack information regarding a radial position (also termed radial depth) of the microcatheters/guidewires within the myocardium. As used herein with respect to the heart, the terms “radial position” and “radial depth” denote a relative position in a single dimension between the endocardial and epicardial surfaces of the heart. Using EDEN, the radial depth of an intracardiac device (such as the ablation microcatheter and/or the navigation guidewire, and if desired, the anchor prongs of the anchor guidewire) may be classified according to its relative position between the endocardial and epicardial borders (or beyond) via a depth navigation classifier (which may be a machine learning or deep learning-based algorithm or a logic-based algorithm) that uses intramyocardial electrograms measured by an electrode of the intracardiac device itself. Different depths between the endocardial and epicardial borders of the myocardium and outside of the myocardium produce different characteristic electrogram waveform features. These waveform features may be extracted and used by the classifier (executed on a signal processor, e.g., a computing device) to differentiate between different radial depth categories.

[0084] In some examples, aspects of the VINTAGE system may be assembled into one or more kits as shown schematically in FIG. 12. A first kit 1200 may include a packaging 1202 housing the ablation microcatheter 102 (including the first mapping electrode 104, the ablation electrode 108 or an ablation electrode of a different configuration, such as an ablation electrode as shown in FIGS. 13-17 and 19, and the second mapping electrode 109, one or more or each or none of which may include helical, feathered, dentate, and/or tapered extensions) and the navigation guidewire 110 (including the exposed conductor 111). In some examples, the packaging 1202 may be sterile packaging. In some examples, each of the ablation microcatheter 102 and the navigation guidewire 110 may be packaged in individual, sterile packages, and the packaging 1202 may not be sterile. A second kit 1201 may include a packaging 1204 housing the accessor catheter 304 (optionally including the first electrode 308 and the second electrode 310, one or more or each or none of which may include helical, feathered, dentate, and/or tapered extensions) and the anchor system (including the anchor shaft 306, the myocardial engagement component 312, and hinge mechanism 314), either as separate components or with the anchor system integrated in the accessor catheter 304. In some examples, the packaging 1204 may be sterile packaging. In some examples, each of the accessor catheter 304 and the anchor system may be packaged in individual, sterile packages, and the packaging 1204 may not be sterile. [0085] In some examples, the second kit 1201 may include the outer catheter 302. Further, in some examples, the first kit 1200 and/or the second kit 1201 may include one or more electrode connectors 1206.

[0086] When the one or more electrode connectors 1206 are included in the first kit 1200, the one or more electrode connectors 1206 may be included in packaging 1202. In still further examples, the first kit 1200 may include connectors, signal wires, and/or other components for connecting the ablation microcatheter and the navigation guidewire to an EAM and/or EDEN signal processor and/or for connecting the ablation microcatheter to the RF generator. When the outer catheter 302 and/or the one or more electrode connectors 1206 are included in the second kit 1201, the outer catheter 302 and/or the one or more electrode connectors 1206 may be included in packaging 1204 (and in some examples, at least the outer catheter 302 may be packaged in individual or common sterile packaging). In still further examples, the second kit 1201 may include connectors, signal wires, and/or other components for connecting the accessor catheter and/or the anchor guidewire to an EAM and/or EDEN signal processor.

[0087] In some examples, the first kit 1200 may include multiple ablation microcatheters and navigation guidewires, such as 5, 10, 25, 50, 100, or more of each of the ablation microcatheter and the navigation guidewire. In such examples, each individual component (e.g., each ablation microcatheter, each navigation guidewire) may be packaged in a separate sterile packaging and all housed within packaging 1202. Alternatively, one of each of the ablation microcatheter and the navigation guidewire may be packaged together in a common, sterile packaging to form a sub-kit, and a plurality of sub-kits (e.g., 5, 10, 25, 50, 100, etc.) may be packaged in packaging 1202. In examples where the first kit 1200 includes the one or more electrode connectors 1206, the first kit 1200 may include multiple sets of the one or more electrode connectors 1206, packaged similarly to the ablation microcatheters and navigation guidewires (e.g., individually or in sub-kits).

[0088] In some examples, the second kit 1201 may include multiple accessor catheters and anchor systems, such as 5, 10, 25, 50, 100, or more of each of the accessor catheter and the anchor system. In such examples, each individual component (e.g., each accessor catheter, each anchor system) may be packaged in a separate sterile packaging and all housed within packaging 1204. Alternatively, one of each of the accessor catheter and the anchor system may be packaged together in a common, sterile packaging to form a sub-kit, and a plurality of sub-kits (e.g., 5, 10, 25, 50, 100, etc.) may be packaged in packaging 1204. In examples where the second kit 1201 includes the outer catheter 302 and/or the one or more electrode connectors 1206, the second kit 1201 may include multiple outer catheters and/or multiple sets of the one or more electrode connectors 1206, packaged similarly to the accessor catheters and anchor guidewires (e.g., individually or in subkits).

[0089] In some examples, the first kit 1200 and the second kit 1201 may be combined into one overall kit. In such examples, each component (e.g., the ablation microcatheter, navigation guidewire, accessor catheter, anchor system, and optionally the outer catheter and/or one or more electrode connectors) may be packaged in a common sterile packaging. In other examples, each individual component may be packaged in a separate sterile packaging and all housed in a common packaging. In still further examples, the overall kit may include multiples of each component (e.g., multiple ablation microcatheters, navigation guidewires, accessor catheters, and anchor systems, and optionally multiple outer catheters and/or multiple sets of electrode connectors, such as 5, 10, 25, 50, 100, or more of each of the ablation microcatheter, the navigation guidewire, the accessor catheter, and the anchor system and optionally the outer catheter and/or electrode connectors), packaged individually in separate sterile packaging or packaged into sub-kit, where each sub-kit includes components for performing one VINTAGE procedure (e.g., an ablation microcatheter, a navigation guidewire, an accessor catheter, an anchor system, and optionally an outer catheter and/or one or more electrode connectors).

[0090] Thus, intramyocardial procedures, such as current ablation therapy for VT, a common and life-threatening disease, are hampered by the relative inaccessibility of deep intramural myocardial targets. For example, arrhythmias originating from deep or anatomically inaccessible locations are hard to reach and treat by currently available technologies, accounting for a high rate of arrhythmia recurrence. The VINTAGE system disclosed herein addresses these issues by providing for ablation electrode navigation inside the beating ventricle and ablation inside the muscle, rather than from endocardial or epicardial surfaces, via delivery of RF energy using the ablation electrode of the ablation microcatheter inside the myocardium and intramyocardial irrigation inside the myocardium prior to and during ablation. The problem of ventricular arrhythmia critical circuit elements inaccessible to conventional endocardial or epicardial radiofrequency ablation is solved with the VINTAGE system by deep intramyocardial ablation electrode access and positioning combined with intramyocardial infiltrative irrigation through the fenestrations of the ablation electrode. The problem of navigating and positioning such deep intramyocardial ablation electrodes is solved with the VINTAGE system by adding elements, for EDEN and for electroanatomic mapping and for multipolar intramyocardial pacing and mapping, to microcatheters and guidewires, which allows visualization and/or depth determination of the microcatheters and guidewires in tandem and relative to each other. The problem of insufficiently large ablation fields is solved with the VINTAGE system by deep intramyocardial infiltration by an intramyocardial infusion and ablation microcatheter larger than, and surrounding, the navigation guidewire. The ablation microcatheter may incorporate multiple features (e.g., fenestrated/segmented irrigation-ablation electrode and electromagnetic tracking and multipolar sensing/pacing elements) into a single over-the-wire catheter. The problem of mostly-orthogonal contact with the right ventricular septal endocardium is solved with the accessor catheter that can accomplish multiple shapes interactively. The problem of inadequate backup support during myocardial entry and navigation is solved with the deployable anchor system and variable radius of curvature of the accessor catheter to provide counter-tr action during intramyocardial guidewire/catheter advancement.

[0091] Thus, a guiding system for positioning an over-the-wire microcatheter is disclosed herein. The over-the-wire microcatheter may include an ablation electrode having one or more openings to allow intramyocardial irrigation; at least two electrodes for intramyocardial unipolar or multipolar mapping, pacing, and registration with electroanatomic mapping; and a tapered distal end to allow delivery into the myocardium over a wire. The guiding system may include an accessor catheter with one or more lumens to accommodate the over-the-wire microcatheter and an anchor system. The accessor catheter may be deflectable or housed in a deflectable outer catheter optionally and may optionally include at least two electrodes for electroanatomic mapping.

[0092] Characteristics of the ablation microcatheter and/or accessor catheter include biocompatibility and hemocompatibility, hydrophilic material that allows tracking over a wire as well as flexibility, a Luer-Lock connector at the proximal hub to allow irrigation with pressurized fluid, and connections to the electroanatomic mapping system and/or ablation generator.

[0093] The ablation microcatheter may have the following characteristics: an outer diameter of 0.025-0.038"; an inner diameter 0.021-0.035" to accommodate an 0.014" guidewire and intramyocardial irrigation through the fenestrations; a tapered tip to an inner diameter of 0.014- 0.018" at the distal opening to track over the guidewire; a fenestrated ablation electrode that is 10- 15 mm in length; at least two electrodes (one on either side of the ablation electrode) that are 1-2 mm in length; and a usable length ranging between 135-175 cm. The ablation microcatheter may optionally include longitudinal grooves inside the central lumen to enhance irrigation fluid delivery.

[0094] The accessor catheter may have the following characteristics: outer diameter approximately 6-8.3 F; usable length 110-135 cm; has an end hole typically having two lumens, one for the delivery of the anchor system and another one for the effector (ablation microcatheter); the deployable anchor system having, in at least one example, three or more sharp prongs -10-15 mm in length; and optionally has at least one distal electrode for registration with electroanatomic mapping. The accessor catheter may have deflectable capabilities with a distal deflectable portion that has a radius of 2-5 cm and deflection angle 0-135 degrees. An alternative design is that the accessor catheter may have a fixed 90-degree distal deflection. A further alternative design is that the accessor catheter is contained within a deflectable catheter with the following characteristics: outer diameter 8-8.5 F; usable length 100-130 cm; distal end hole for the accessor catheter to exit; distal deflectable portion with variable radius of deflection 2-5 cm and deflection angle 0-135 degrees. The guiding system may include a proximal handle to control radius and angle of deflection, loading, and manipulation of the accessor catheter, and loading and manipulation of the effector (e.g., ablation microcatheter). The deflectable catheter may be delivered over an 0.035” guidewire or a dilator.

[0095] A method for VINTAGE using the herein described microcatheter use may include: percutaneous access to the femoral vein; use of a commercially available deflectable sheath to get into the right ventricle through the tricuspid valve; engagement of the right ventricular septum using the accessor catheter, the angle of engagement is controlled by either deflectable characteristics of the accessor catheter or the deflectable outer catheter; the accessor catheter is registered within the EAM and/or EDEN to confirm location; release of the myocardial engagement component of the anchor system in the myocardium for support and counter-traction; right ventricular septum entry through the second lumen of the accessor catheter, using a stiff 0.014” guidewire housed inside the effector; navigation of the 0.014” guidewire within the myocardium in tandem with the VINTAGE effector; once at target, intramyocardial irrigation and ablation is performed through the fenestrated/segmented ablation electrode. [0096] Optionally, the electrodes (of the ablation microcatheter and/or accessor catheter) may have helical, feathered, dentate, and/or tapered tails/extensions to ease bonding to the catheter shaft during manufacturing and thereby reduce risk of dislodgement/embolization. Additionally, the fenestrations may not be circular (e.g., the ablation electrode may include strip-like openings or clamshell-like openings) and/or the fenestrations may be distributed to allow the electrode to be oriented to effect infdtration asymmetrically towards intended targets and thereby creating an asymmetric ablation field. Materials options include molybdenum-rhenium allows lower profile.

[0097] Thus, the VINTAGE system disclosed herein is configured for guidewire navigation to intramyocardial targets and ablation in the myocardium with a fenestrated or otherwise segmented ablation electrode. The ablation electrode may include one or more openings to facilitate irrigation during ablation. The one or more openings may be static (e.g., fixed in size and position) or dynamic (e.g., the size of each opening may be adjustable and/or the one or openings may be exposed upon actuation of a particular component) and may be of any suitable shape, including but not limited to circular, semi-circular, oval, rectangular, spiral, helical, sinusoidal, clamshell, and the like. As shown in FIGS. 1-2 and described above, the VINTAGE system may include an ablation microcatheter including a polymer tube and a fenestrated, conductive ablation electrode coupled to the polymer tube near a distal tip of the polymer tube. The ablation microcatheter (e.g., polymer tube) is configured for coaxial arrangement with a navigation guidewire and has an inner lumen with a greater cross-sectional diameter than a cross-sectional diameter of the navigation guidewire. The size mismatch between the inner lumen of the ablation microcatheter and the navigation guidewire may facilitate irrigation from openings (e.g., fenestrations) of the ablation electrode, via irrigant in the inner lumen, during ablation.

[0098] However, other configurations of the VINTAGE system are possible without departing from the scope of this disclosure. As shown in FIGS. 13 and 14, the ablation electrode may be segmented to include or expose openings for irrigation. For example, the ablation electrode may include one or more tines that may be configured to move outward from the ablation electrode to expose strip-like openings in the ablation electrode, as shown in FIG. 13, or the ablation electrode may be comprised of electrode strips configured to bend/flex so as to form clamshelllike openings in the ablation electrode, as shown in FIG. 14. Further, as depicted in FIG. 15, the electrode strips may be wound partially around a central axis of the ablation electrode in a helicallike fashion such that when the strips bend/flex, helical openings are formed. In still further examples, the ablation electrode may be comprised of a continuous segment of material that is wound around the central axis of the ablation electrode to form a single helical opening that spans the length of the ablation electrode, as shown in FIGS. 16 and 17. The ablation electrode may be coupled to the polymer tube in an end-to-end fashion, such that the polymer tube does not extend in the region where the ablation electrode is located, as shown in FIG. 18. In other examples, as shown in FIG. 19, the polymer tube may extend along an inner surface of the ablation electrode.

[0099] In some examples, the ablation microcatheter further includes one or more mapping electrodes configured to facilitate tracking by electroanatomic navigation (also known as electroanatomic mapping), focal electrogram sensing, and/or focal myocardial pacing. The one or more mapping electrodes may include a first mapping electrode positioned at a distal end of the ablation microcatheter (e.g., between the ablation electrode and the distal tip of the polymer tube). In some examples, the one or more mapping electrodes may include a second mapping electrode positioned proximal the first mapping electrode, such as on an opposite side (e.g., proximal) of the ablation electrode. For example, as shown in FIGS. 1-2, the first mapping electrode may be positioned closer to the ablation electrode, or the first mapping electrode may be positioned further from the ablation electrode (and closer to the distal tip of the ablation microcatheter), as shown in FIG. 20. In some examples, to facilitate reduction in electrode detachment from the ablation microcatheter, the one or more mapping electrodes and/or the ablation electrode may include helical, feathered, dentate, and/or tapered extensions, as shown in FIGS. 21 and 22, that may be incorporated into the polymer tube of the ablation microcatheter, as shown in FIGS. 23 and 24.

[0100] As described above, at least the ablation microcatheter and the navigation guidewire may be used to traverse the myocardium to reach an ablation target, guided by electrograms detected from the electrodes on the ablation microcatheter and guidewire, or by position information encoded on electromagnetic fields generated by electroanatomic mapping systems. Irrigation with an electrolyte may be performed via the flush port and fenestrations/openings of the ablation microcatheter and ablation performed with the ablation electrode, to alter the electrical and/or physicochemical characteristics of the target myocardial substrate. Aspects of the VINTAGE system, including the ablation microcatheter and the navigation guidewire, may be packaged in a kit, as shown in FIG. 12 and described above.

[0101] FIGS. 13 and 14 provide additional example configurations for segmented ablation electrodes. FIG. 13 shows a second ablation electrode 1302 that may be incorporated into ablation microcatheter 102. Second ablation electrode 1302 may be positioned on the ablation microcatheter 102 similarly to ablation electrode 108, and may be comprised of the same material(s), have the same length, and have the same inner diameter as the ablation electrode 108. Rather than include a plurality of fenestrations, the second ablation electrode 1302 may include a main body 1304 supporting a plurality of tines, such as a first tine 1306 and a second tine 1308. Each tine of the plurality of tines may be shaped and sized to be accommodated in a respective opening of the second ablation electrode 1302 and may be pre-tensioned or otherwise configured to move outward from the central axis of the second ablation electrode 1302 to expose the respective opening. For example, the first tine 1306 may be shaped and sized to be accommodated within a first opening 1310, and may move outward from the first opening 1310 to facilitate fluidic coupling between the inner lumen of the ablation microcatheter 102 and the surrounding environment, via the first opening 1310. Likewise, the second tine 1308 may be shaped and sized to be accommodated within a second opening 1312, and may move outward from the second opening 1312 to facilitate fluidic coupling between the inner lumen of the ablation microcatheter 102 and the surrounding environment, via the second opening 1312. In the example shown in FIG. 13, the plurality of tines may include six tines and the second ablation electrode 1302 may include six openings. The openings may be strip-like in shape (e.g., have a length along the x axis that is larger than a radial width of the opening around the circumference of the second ablation electrode 1302), with square corners or rounded comers. The openings (and hence tines) may be arranged in two radial groups that are offset from each other (e.g., the openings in the two groups are not aligned along the x axis) so that, looking down the ablation microcatheter 102 when the tines are positioned in the outward position as shown in FIG. 13, the tines are arranged radially around the second ablation electrode 1302 in an evenly spaced manner. The main body 1304 may extend around each opening so as to be electrically continuous. The tines may be extensible or retractable tines to increase the electric field size of the ablation electrode and that allow the tines to be withdrawn from an initial low-profile intramyocardial delivery tract. For example, an outer sheath may be provided over the ablation microcatheter 102 that has an inner diameter that matches the outer diameter of the ablation microcatheter 102 but allows sliding of the ablation microcatheter 102 relative to the outer sheath. The outer sheath may extend at least along the second ablation electrode 1302 during delivery of the ablation microcatheter 102, may not include a tapered distal end, and may be positioned with its distal terminating end at approximately the first mapping electrode 104 during navigation of the ablation microcatheter 102 through the myocardium. Once at target, the outer sheath may be moved proximally to expose the second ablation electrode 1302 and allow the tines to move outward. After ablation, the outer sheath may be moved distally to reposition the tines in their respective openings.

[0102] FIG. 14 shows a third ablation electrode 1402 that may be incorporated into ablation microcatheter 102. Third ablation electrode 1402 may be positioned on the ablation microcatheter 102 similarly to ablation electrode 108, and may be comprised of the same material(s), have the same length, and have the same inner diameter as the ablation electrode 108. Rather than include a plurality of fenestrations, the third ablation electrode 1402 may include a plurality of electrode strips coupled between a first ring segment 1404 and a second ring segment 1406. For example, the plurality of electrode strips may include a first strip 1408 and a second strip 1410. Each strip may be electrically coupled to the first ring segment 1404 and the second ring segment 1406. Further, each strip may be bendable/flexible to allow the strips to move from being substantially straight to being bent outward, away from the central axis of the ablation microcatheter 102, to thereby form a plurality of clamshell-like openings. The ablation microcatheter 102 may include pull-cables or another actuation mechanism that, when actuated, pulls the first ring segment 1404 (and components of the ablation microcatheter 102 distal of the first ring segment 1404) closer to the second ring segment 1406. When the first ring segment 1404 and the second ring segment 1406 are at a maximum distance from each other, each strip of the plurality of strips is substantially straight (e g., extends in parallel to the x axis) and in close alignment with neighboring strips along the outer circumference of the ablation microcatheter 102. When the first ring segment 1404 is moved closer to the second ring segment 1406, each strip of the plurality of strips bends outward to form an opening between each pair of neighboring strips, such as first opening 1412. The openings may be considered to have a clamshell-like shape due to the rounding upward and downward of the strips forming the openings. The size of each opening may be controlled by controlling the distance between the first ring segment 1404 and the second ring segment 1406. During navigation of the ablation microcatheter 102 to the target, the first ring segment 1404 may be held at the maximum distance from the second ring segment 1406 to keep the strips in the low- profile position for traversing the myocardium. Once at target, the first ring segment 1404 may be pulled proximally to create openings for irrigation and increase the electric field size of the ablation electrode. [0103] In some examples, the ablation electrode may have spiral/helical and/or sinusoidal openings, which may be static openings (e.g., that are fixed in place) or dynamic openings (e.g., that can be exposed and closed). For example, FIG. 15 shows a fourth ablation electrode 1502 that may be incorporated into ablation microcatheter 102. Fourth ablation electrode 1502 may be positioned on the ablation microcatheter 102 similarly to ablation electrode 108, and may be comprised of the same material(s), have the same length, and have the same inner diameter as the ablation electrode 108. Similar to the third ablation electrode 1402, the fourth ablation electrode 1502 may include a plurality of electrode strips coupled between a first ring segment 1504 and a second ring segment 1506. For example, the plurality of electrode strips may include a first strip 1508 and a second strip 1510. Each strip may be electrically coupled to the first ring segment 1504 and the second ring segment 1506. However, unlike the strips of the third ablation electrode 1402, the strips of the fourth ablation electrode 1502 are wound partially around the central axis of the ablation electrode/ablation microcatheter. For example, the first strip 1508 may couple to the second ring segment 1506 at a first position and couple to the first ring segment 1504 at a second positon that is radially offset from the first position (e.g., by 180 degrees or another suitable amount).

[0104] Further, each strip may be bendable/flexible to allow the strips to move from being extended (e.g., at full length) to being bent outward, away from the central axis of the ablation microcatheter 102, to thereby form a plurality of helical-like openings. The ablation microcatheter 102 may include pull-cables or another actuation mechanism that, when actuated, pulls the first ring segment 1504 (and components of the ablation microcatheter 102 distal of the first ring segment 1504) closer to the second ring segment 1506. When the first ring segment 1504 and the second ring segment 1506 are at a maximum distance from each other, each strip of the plurality of strips is held in close alignment with neighboring strips along the outer circumference of the ablation microcatheter 102. When the first ring segment 1504 is moved closer to the second ring segment 1506, each strip of the plurality of strips bends outward to form an opening between each pair of neighboring strips, such as first opening 1512. The openings may be considered to have a helical-like shape due the winding of each opening around the central axis. The size of each opening may be controlled by controlling the distance between the first ring segment 1504 and the second ring segment 1506. During navigation of the ablation microcatheter 102 to the target, the first ring segment 1504 may be held at the maximum distance from the second ring segment 1506 to keep the strips in the low-profile position for traversing the myocardium. Once at target, the first ring segment 1504 may be pulled proximally to create openings for irrigation and increase the electric field size of the ablation electrode.

[0105] Still further examples of helical ablation electrode configurations are shown in FIGS. 16 and 17. FIG. 16 shows a fifth ablation electrode 1602 that may be incorporated into ablation microcatheter 102. Fifth ablation electrode 1602 may be positioned on the ablation microcatheter 102 similarly to ablation electrode 108, and may be comprised of the same material(s), have the same length, and have the same inner diameter as the ablation electrode 108. The fifth ablation electrode 1602 may be a helical electrode comprised of an electrode strip 1604 having a constant width that is wound around the central axis of the ablation microcatheter in a helical fashion. The electrode strip 1604 may extend continuously from a proximal end to a distal end of the fifth ablation electrode 1602. The helical winding of the electrode strip 1604 may create a continuous helical opening 1606 between turns of the electrode strip 1604. In the example shown in FIG. 16, the electrode strip 1604 may be wound relatively loosely to create a relatively large/wide helical opening 1606. For example, the helical opening 1606 may be such that, along an axis parallel to the x axis, the helical opening 1606 may have a first width W1 between two segments of the electrode strip 1604 that is equal to a second width W2 of the electrode strip 1604. Thus, the inner lumen of the ablation microcatheter 102 may be fluidly coupled to ambient via the helical opening 1606 and the amount of irrigant directed out of the fifth ablation electrode 1602 may be a function of the size of the helical opening 1606. Accordingly, the size of the helical opening may be selected based on desired irrigation properties during ablation, and the helical pitch of the electrode strip may be set to create the helical opening of the desired size. It is to be appreciated that the helical opening may be wider than shown in FIG. 16, or may be smaller, as shown in FIG. 17 and discussed below.

[0106] FIG. 17 shows a sixth ablation electrode 1702 that may be incorporated into ablation microcatheter 102. Sixth ablation electrode 1702 may be positioned on the ablation microcatheter 102 similarly to ablation electrode 108, and may be comprised of the same material(s), have the same length, and have the same inner diameter as the ablation electrode 108. The sixth ablation electrode 1702 may be a helical electrode comprised of an electrode strip 1704 having a constant width that is wound around the central axis of the ablation microcatheter in a helical fashion, similar to the fifth ablation electrode 1602, to create a continuous helical opening 1706 between turns of the electrode strip 1704. In the example shown in FIG. 17, the electrode strip 1704 may be wound relatively tightly to create a relatively small helical opening 1706. For example, the helical opening 1706 may be such that, along an axis parallel to the x axis, the helical opening 1706 may have a first width W1 between two segments of the electrode strip 1704 that is smaller than a second width W2 of the electrode strip 1704 (e g., the second width W2 may be twice as large as the first width Wl, three times as large, or another suitable amount).

[0107] The example ablation electrodes shown in FIGS. 2 and 13-17 may be metal-only electrodes, such that the polymer tube does not extend coaxially with the ablation electrode. For example, FIG. 18 shows a cross-section of a portion of the ablation microcatheter 102 with the ablation electrode 108 taken along the x axis. FIG. 18 shows that the polymer tube terminates at the proximal end of the ablation electrode 108 (e.g., at the third insulating segment 205) and the distal end of the ablation electrode 108 (e g., at the second insulating segment 204) and does not extend across the ablation electrode 108. However, other configurations are possible where the polymer tube extends along the inner surface of the ablation electrode, as shown in FIG. 19.

[0108] FIG. 19 shows a cross-section of a portion of the ablation microcatheter 102 with an ablation electrode 1908 taken along the x axis. In the example shown in FIG. 19, the ablation electrode 1908 is identical to ablation electrode 108, other than the ablation electrode 1908 has a smaller thickness, to thereby have a larger inner diameter than the inner diameter of the ablation electrode 108. The polymer tube includes a lining 1902 that lines the inner surface of the ablation electrode 1908 (e g., an outer surface of the lining 1902 may be in face-sharing contact with the inner surface of the ablation electrode 1908). The lining 1902 may be in contact with and extend from the third insulating segment 205 and the second insulating segment 204. The lining 1902 may include fenestrations of the same size, shape, and placement of the fenestrations of the ablation electrode 1908 to ensure that the fluidic coupling between the inner lumen of the ablation microcatheter 102 and the area surrounding the ablation electrode 1908 is maintained. In the example of FIG. 19, the ablation electrode 1908 may have an inner diameter of 0.020 inches and an outer diameter of 0.025 inches and the lining 1902 may have an inner diameter of 0.015 inches and an outer diameter of 0.020 inches. However, other diameters are possible without departing from the scope of this disclosure. For example, the ablation electrode 1908 may have an inner diameter of 0.018 inches and an outer diameter of 0.025 inches and the lining 1902 may have an inner diameter of 0.015 inches and an outer diameter of 0.018 inches. As another example, the ablation electrode 1908 may have an inner diameter of 0.022 inches and an outer diameter of 0.025 inches and the lining 1902 may have an inner diameter of 0.015 inches and an outer diameter of 0.022 inches. As a still further example, the ablation electrode 1908 may have an inner diameter of 0.024 inches and an outer diameter of 0.025 inches and the lining 1902 may have an inner diameter of 0.015 inches and an outer diameter of 0.024 inches.

[0109] It is to be appreciated that ablation electrode 1908 may be configured similarly to the second ablation electrode 1302, the third ablation electrode 1402, the fourth ablation electrode 1502, the fifth ablation electrode 1602, or the sixth ablation electrode 1702 and thus include openings of other size, shape, or placement than the fenestrations shown in FIG. 19. In such examples, the lining 1902 may include openings of the same size, shape, and placement of the openings of the ablation electrode 1908.

[0110] Thus, in some examples, the polymer tube may extend across the ablation electrode and have a desired thickness; the outer diameter of the ablation microcatheter and the size of the inner lumen of the ablation microcatheter may be ensured by adjusting the thickness of the ablation electrode. The segment of the polymer tube that extends across the ablation electrode (referred to above as the lining) may have openings that match the openings of the ablation electrode to facilitate irrigation via the ablation electrode. In some examples, the ablation electrode may be configured to rotate at least some around the central axis, which may thereby adjust the alignment between the openings of the lining and the openings of the ablation electrode, to provide a level of control over the amount of irrigation provided during ablation. The lining may be comprised of the same material as the polymer tube.

[OUl] FIG. 20 shows another magnified view of the distal end of the ablation microcatheter 102, showing the distal tip 105, tapered nosecone 106, first mapping electrode 104, ablation electrode 108, second mapping electrode 109, and body 103. The ablation microcatheter 102 shown in FIG. 20 is similar to the ablation microcatheter shown in FIG. 2. However, the first mapping electrode 104 of the ablation microcatheter 102 of FIG. 20 is positioned on the tapered nosecone 106. Thus, the first mapping electrode 104 in FIG. 20 likewise tapers and may be spaced apart from the ablation electrode 108 by a larger amount than the first mapping electrode 104 in FIG. 2.

[0112] The electrodes of the ablation microcatheter 102 shown in FIGS. 2, 13-17, and 20 may be ring electrodes with straight/flat edges that may be mounted on the ablation microcatheter 102 by bonding the edges of the electrodes to the material of the nosecone, first insulating segment, second insulating segment, and/or body using glue, heat, and/or other mechanisms, such as embedding the electrodes in the shaft by reflowing or extruding the shaft material segments before and after the mapping electrodes. However, the straight edges of the electrodes may not adhere to the elements of the ablation microcatheter as reliably as desired for all applications and may be prone to dislodging. Thus, one or more of the electrodes may include extensions at the edges that allow enhanced bonding to the polymer components of the ablation microcatheter (e.g., the nosecone, first insulating segment, second insulating segment, and/or body) and providing smoother mechanical transition from the polymer catheter shaft to the metal electrode body. The extensions may be helical, feathered, dentate, and/or tapered to allow embedding of the extensions in the polymer tube and increase the contact area between the electrode edges and the polymer tube. The extensions, and in particular helical configurations of the extensions, may enhance EAM tracking functionality.

[0113] FIG. 21 shows an example mapping electrode 2100 with helical extensions. Mapping electrode 2100 is a non-limiting example of the first mapping electrode 104 and/or the second mapping electrode 109 of FIG. 1 and may be included on the ablation microcatheter 102. The mapping electrode 2100 may include a ring electrode segment 2102 that comprises a hollow, circular (e.g., annular) electrode, as explained above with respect to the first mapping electrode 104, for example. The mapping electrode 2100 may further include a first extension 2104 and a second extension 2106, each extending out from a respective side of the ring electrode segment 2102. The first extension 2104 may be a helical extension made of the same material as the ring electrode segment 2102 and including a suitable number of turns (e.g., one and a half). In some examples, the entirety of the first extension 2104 may have the same inner and outer diameter as the ring electrode segment 2102. In other examples, the first extension 2104 may taper (e.g., narrow) in a direction away from the ring electrode segment 2102. FIG. 21 may be a front-side view of the mapping electrode 2100, and the first extension 2104 may extend out of the ring electrode segment 2102 on an opposite, back side of the mapping electrode 2100. The second extension 2106 may be a helical extension made of the same material as the ring electrode segment 2102 and with a suitable number of turns (e.g., one and a half). In some examples, the entirety of the second extension 2106 may have the same inner and outer diameter as the ring electrode segment 2102. In other examples, the second extension 2106 may taper (e.g., narrow) in a direction away from the ring electrode segment 2102. The second extension 2106 may extend out of the ring electrode segment 2102 on the back side of the mapping electrode 2100. The first extension 2104 may extend out of the ring electrode segment 2102 closer to a bottom of the mapping electrode 2100 while the second extension 2106 may extend out of the ring electrode segment 2102 closer to a top of the mapping electrode 2100. In all, the first extension 2104, the ring electrode segment 2102, and the second extension 2106 may create a helical shape with a suitable number of turns (e.g., four), with a middle section of increased width.

[0114] FIG. 22 shows an example ablation electrode 2200 with helical extensions. Ablation electrode 2200 is a non-limiting example of the ablation electrode 108 of FIG. 1 and may be included on the ablation microcatheter 102. The ablation electrode 2200 may include an ablation electrode segment 2202 that comprises a hollow, circular (e.g., annular) electrode with fenestrations or segmentations, as explained above with respect to the ablation electrode 108, for example. The ablation electrode 2200 may further include a first extension 2204 and a second extension 2206, each extending out from a respective side of the ablation electrode segment 2202. The first extension 2204 and the second extension 2206 may be similar to the first extension 2104 and the second extension 2106 of FIG. 21, and thus the description of the first extension 2104 and the second extension 2106 provided above likewise applies to the first extension 2104 and the second extension 2106.

[0115] FIG. 23 shows an example ablation catheter 2302 with electrodes removed to allow visualization of the connecting components of the ablation catheter 2302 that facilitate coupling of the electrodes to the ablation catheter 2302. In the example shown in FIG. 23, the first mapping electrode and the second mapping electrode are electrodes with coupling extensions (such as the mapping electrode 2100 of FIG. 21) and thus the ablation catheter 2302 includes coupling sections to facilitate enhanced bonding of the electrode extensions. The coupling sections include a first section 2310 coupled to the nosecone 2306 and a second section 2312, wherein the first section 2310 and the second section 2312 are configured to couple to the first mapping electrode (not shown in FIG. 23, but shown in FIG. 24). The first section 2310 is a non-limiting example of the first insulating segment 202 and the second section 2312 is a non-limiting example of the second insulating segment 204. The coupling sections additionally include a third section 2314 and a portion of the body 2303, wherein the third section 2314 and the portion of the body 2303 are configured to couple to the second mapping electrode. The third section 2314 is a non-limiting example of the third insulating segment 205 and the body 2303 is a non-limiting example of the body 103. The second section 2312 and the third section 2314 are additionally configured to couple to an ablation electrode 2308, which is a non-limiting example of the ablation electrode 108. In the illustrated example, the ablation electrode 2308 does not include extensions.

[0116] As appreciated from FIG. 23, the first section 2310, the second section 2312, the third section 2314, and the portion of the body 2303 each include a helical gap that is shaped and sized to accommodate a respective electrode extension. FIG. 24 shows the ablation catheter 2302 with electrodes coupled the ablation catheter 2302. For example, a first mapping electrode 2304 is coupled to the first section 2310 on a first side and to the second section 2312 on a second side. The first mapping electrode 2304 may be a non-limiting example of the mapping electrode 2100 and thus includes two extensions. The first extension of the first mapping electrode 2304 may be coupled to the first section 2310 and the second extension of the first mapping electrode 2304 may be coupled to the second section 2312. As shown, the first extension may fit into the helical gap of the first section 2310 and the second extension of the first mapping electrode 2304 may fit into the helical gap of the second section 2312. The second mapping electrode 2309 may be coupled to the third section 2314 and the portion of the body 2303 in a similar manner.

[0117] The inclusion of the electrode extensions may increase the surface area over which the electrodes are coupled to the connecting elements of the ablation catheter, thereby increasing the durability of the bonding. It is to be appreciated that the electrode extensions may taper/narrow in diameter in a direction away from the ring electrode component, as explained above. Further, the mapping electrodes may be coupled to the microcatheter shaft during reflowing or extruding of the shaft material segments distal and proximal the mapping electrodes. In doing so, the electrode surface may be aligned with the shaft surface almost perfectly for a smooth profile and the mapping electrodes may be embedded into the shaft to provide a smoother mechanical transition, preventing kinks and detachment of the electrodes, and further enhancing EAM tracking functionality. The electrode extensions may be fully or partially embedded in the shaft/polymer tube. The electrode segment of the mapping electrode may not be covered by the polymer tube and thus an outer surface of the electrode segment may be exposed to ambient. When the electrode extensions are tapered and thus narrow in cross-sectional diameter in a direction away from the electrode segment, the amount of polymer on the outside and the inside of the extensions may vary along the extensions. For example, the thickness of the polymer on the outer side of the extension may increase in a direction away from the electrode segment. Because the electrodes may be coupled to the polymer tube during formation of the polymer tube (e.g., via reflowing or extruding), the helical gaps in the polymer tube described above may not be pre-formed but may reflect areas where the electrode extensions are included on and/or within the polymer tube.

[0118] The example ablation catheter system described above includes an ablation electrode with openings in the ablation electrode itself to facilitate irrigation before and/or during ablation. However, in some examples, a VINTAGE system may include the ablation electrode being carried on a separate catheter with irrigation provided via a gap between coaxially arranged catheters. For example, as shown in FIGS. 25-27, the ablation catheter system may include a first microcatheter including a first electrode, a second microcatheter including a second electrode, a navigation guidewire including a third electrode, and an ablation electrode configured for coaxial arrangement. The first microcatheter may be sized to accommodate the second microcatheter and alternately the ablation electrode, and the second microcatheter may be sized to accommodate the navigation guidewire. In still other examples, shown in FIGS. 28 and 29, the ablation catheter system may include a first microcatheter, a removable dilator, a navigation guidewire, and an ablation electrode configured for coaxial arrangement. At least the first microcatheter and the navigation guidewire may be used to traverse the myocardium to reach an ablation target, guided by electrograms generated from the electrodes on the first microcatheter and navigation guidewire, at which point the navigation guidewire may be removed and replaced with the ablation electrode. Irrigation with an electrolyte may be performed via the first microcatheter and ablation performed with the ablation electrode. Aspects of the VINTAGE system, including the first microcatheter, the navigation guidewire, and the ablation electrode may be packaged in a kit, as shown in FIGS. 30 and 31.

[0119] FIG. 25 depicts a second example ablation catheter system 2500 (also referred to as a VINTAGE system), in a first configuration 2501. The catheter system 2500 includes a first microcatheter 2502 that includes a first electrode 2504 (e.g., a surface ring electrode) at a distal end of the first microcatheter 2502. The first microcatheter 2502 may have a generally cylindrical shape with a hollow interior to facilitate a coaxial arrangement of a second microcatheter 2506. The first microcatheter 2502 may include a distal tip 2505 that has an opening through which the second microcatheter 2506 may extend. At the distal tip, the first microcatheter 2502 may have a first cross-sectional diameter (e.g., along the z axis) of at least 0.035 inches (e.g., 0.9 mm). For example, the first cross-sectional diameter may be in a range of 0.035-8 inches. The distal tip 2505 may taper in width/cross-sectional area along the x axis (and specifically may taper in the negative x direction). Accordingly, at least in some examples, the first microcatheter 2502 may have a larger cross-sectional area in the body/main shaft portion (e.g., proximal of the first electrode 2504) than at the distal tip 2505. The first electrode 2504 may be positioned adjacent the distal tip 2505, though the first electrode 2504 may be positioned elsewhere on the first microcatheter 2502 without departing from the scope of this disclosure.

[0120] The first microcatheter 2502 may have a suitable length (e g., along the x axis) to facilitate placement of the first microcatheter 2502 in a patient and specifically to facilitate placement of the distal end of the first microcatheter 2502 in a heart of the patient while the proximal end of the first microcatheter 2502 remains external to the patient. The first microcatheter 2502 may include an opening at the distal tip 2505 to allow insertion and removal of the second microcatheter 2506 as well as an opening at the proximal end. At the proximal end, the first microcatheter 2502 may include and/or be coupled to various hardware 112 to facilitate navigation of the first microcatheter 2502 as well as fluid irrigation during an ablation procedure, similar to the hardware explained above with respect to the ablation catheter system 100.

[0121] Thus, the first microcatheter 2502 includes a surface ring electrode allowing intramyocardial EAM tracking. The first microcatheter 2502 is capable of delivering and tracking the second microcatheter 2506, is capable of intramyocardial pacing, is capable of deep intramyocardial positioning under x-ray/EAM guidance, and is capable of infusing electrolyte around an ablation guidewire/catheter (as explained below). The first microcatheter 2502 includes an electrode connector for EAM. The first microcatheter 2502 may be electrically insulated from coaxial microcatheters and surrounding catheters and media. The first microcatheter 2502 may have a "short" rotating hemostatic valve/adaptor (e.g., of less than 2cm) and allows coaxial placement of the second microcatheter 2506 as well as a sidearm (e.g., the irrigation port 112a) to allow electrolyte infusion. The first microcatheter 2502 may have a length of 110cm.

[0122] The second microcatheter 2506 may include a second electrode 2508 at the distal end of the second microcatheter 2506 (e.g., a surface ring electrode). Similar to the first microcatheter 2502, the second microcatheter 2506 may have a generally cylindrical shape with a hollow interior to facilitate a coaxial arrangement of a navigation guidewire 110, which is the same or similar to the navigation guidewire 110 of the ablation catheter system 100. The second microcatheter 2506 may include a distal tip 2509 that has an opening through which the navigation guidewire 110 may extend. At the distal tip 2509, the second microcatheter 2506 may have a second cross-sectional diameter (e.g., along the z axis) of less than 0.035 inches (e.g., 0.9mm), such as 0.014 inches (e.g., 0.35mm) or another diameter that is smaller than the first cross-sectional diameter of the first microcatheter 2502, so that the second microcatheter 2506 may be housed within and move relative to the first microcatheter 2502, with the second cross-sectional diameter being large enough to accommodate the navigation guidewire 110. The second microcatheter 2506 may have a suitable length (e.g., along the x axis) to facilitate placement of the second microcatheter 2506 in the heart of the patient while the proximal end of the second microcatheter 2506 remains external to the patient, which may include the second microcatheter 2506 being longer than the first microcatheter 2502. At the proximal end, the second microcatheter 2506 may include various hardware 114 to facilitate navigation of the second microcatheter 2506 during an ablation procedure. The hardware 114 may include a second electrode connector and/or a hemostatic valve. The second electrode connector may be coupled to the signal processor, for example, via a third connection 120 (e.g., a signal wire) and may be similar to the first electrode connector. As explained above, the hemostatic valve may be integrated with the second microcatheter 2506, be detachable and connectable to the second microcatheter 2506 via a connector of the second microcatheter 2506, or be omitted entirely. The second electrode 2508 may be coupled to the second electrode connector via a suitable connection, such as a wire extending along or within a wall forming the second microcatheter 2506. The second microcatheter 2506 may thus include a distal surface ring electrode 2508 allowing intramyocardial EAM tracking and mapping. The second microcatheter 2506 may be capable of delivering and tracking the navigation guidewire 110, and may include radiopaque markers allowing fluoroscopic tracking. The second microcatheter 2506 includes a second electrode connector for EAM/EDEN. The second microcatheter 2506 may be electrically insulated from coaxial guidewires and surrounding microcatheters and media. The second microcatheter 2506 may have a length of 150cm.

[0123] As explained previously, a length of the navigation guidewire 110 is electrically insulated except for an exposed conductor 111 at the distal end of the navigation guidewire 110 and a connection point at the proximal end of the navigation guidewire 110. For example, the navigation guidewire 110 may be coated with one or more insulators except for the exposed conductor 111 and the connection point that electrically couples the exposed conductor to the electrode connector 116 via the electrically conductive transmission line. In this way, the navigation guidewire 110 may include an insulated region and an uninsulated region (e.g., the exposed conductor 111). The electrode of the navigation guidewire (e.g., the exposed conductor 111) may be a unipolar electrode in some examples. The electrode connector 116 may be coupled to the signal processor, for example, via the second connection 122 (e g., a signal wire), as explained previously. The third electrode connector may be configured to limit the mechanical limitation on the operator torqueing the navigation guidewire during operation/advancement/retraction, to ensure tactile feedback and to minimize physical constraints on torque/advancement/withdrawal. The navigation guidewire 110 may have a tip stiffness (measured by lateral deflection at a fixed distance from the tip, such as 10mm) at the distal end of the navigation guidewire 110 ranging from 6 to 60g, such as 20-40g, allowing a short l-2mm x 30° "CTO" curve, as well as a straight tip (e.g., at the proximal end), each with electrical insulation to allow EDEN and EAM tracking. The navigation guidewire 110 may include radiopaque markers allowing fluoroscopic tracking. The distal tip of the navigation guidewire 110 has an insulation- free segment ~lmm in length, for EAM/EDEN; the proximal tip of the navigation guidewire 110 has an insulation-free segment ~10mm in length, for attachment to a detachable electrode connector 116 to allow EAM/EDEN. The length of the navigation guidewire 110 may be 200- 300cm, in some examples.

[0124] Thus, the catheter system 2500 in the first configuration 2501 includes a coaxial arrangement of the first microcatheter 2502, the second microcatheter 2506, and the navigation guidewire 110, with the navigation guidewire 110 accommodated within the second microcatheter 2506 and the second microcatheter 2506 accommodated within the first microcatheter 2502. During an ablation procedure, the catheter system 2500 in the first configuration 2501 may be navigated to the heart (e.g., via a guiding sheath and/or catheter in some examples, or via the accessor catheter described above) and advanced into the myocardium, to any target within the wall of the left ventricle, for example. Navigation of the catheter system 2500 may be guided by biplane x-ray fluoroscopy, EAM, EDEN, and/or intracardiac echocardiography (ICE).

[0125] Once the navigation guidewire 110, second microcatheter 2506, and first microcatheter 2502 reach the target, the second microcatheter 2506 and navigation guidewire 110 are removed from the first microcatheter 2502 and replaced with an ablation electrode, to thereby form the catheter system 2500 in a second configuration 2601 that is shown in FIG. 26. Thus, in the second configuration 2601, the catheter system 2500 includes the first microcatheter 2502 and an ablation electrode 2602 accommodated within the first microcatheter 2502. The ablation electrode 2602 may be a guidewire comprised of stainless steel and coated in in an insulating coating (e.g., PTFE) other than at a distal tip and a proximal tip of the ablation guidewire. In other examples, the ablation electrode may be a guidewire or catheter with an ablation electrode at the tip of the guidewire or catheter. The ablation electrode 2602 may have a suitable diameter that is selected to facilitate sufficient ablation of the target while also allowing navigation through the myocardium, such as 0.025 inches (0.635 mm). Thus, the ablation electrode 2602 may include electrical insulation and be configured to facilitate RF ablation, EDEN, and EAM tracking, with an insulation-free intramyocardial distal end approximately 10mm in length (~20mm² exposed surface area), and similar insulation-free proximal end for connection to a detachable electrode connector 2605 (via which the ablation electrode 2602 may also be coupled to an RF generator, explained below). The electrode connector 2605 may include a connection 2607 (e.g., signal wire) to the signal processor for EAM and/or EDEN.

[0126] The relatively large diameter of the first microcatheter 2502 (and the irrigation port 112a) may facilitate irrigation of the target with an electrolyte prior to and during ablation, to create a virtual ablation electrode 2604. The irrigation may be facilitated by the irrigation pump 206 fluidly coupled to the irrigation port 112a, similar to the process explained above. When the irrigation pump 206 is coupled to the irrigation port 112a and the irrigation pump 206 is activated, the electrolyte may be pumped through the interior of the first microcatheter 2502 and out of the opening at the distal tip 2505 of the first microcatheter 2502. The irrigation pump 206 may be capable of infusing intramyocardial ionic irrigant (such as 0.9% (normal) or 0.45% (half-normal) saline solution). In some examples, the irrigation pump 206 may include timing and gating circuitry to automate initiation of infusion/infiltration/irrigation approximately 1 minute before initiation of RF ablation, and continuing at approximately the same rate for the duration of the RF ablation.

[0127] Ablation may be achieved via the RF generator 208, as explained above, coupled to the ablation electrode 2602 at the proximal tip of the ablation electrode 2602 (e.g., via a connector such as an ablation catheter), which may be activated to deliver RF energy to the target via the ablation electrode 2602 and virtual ablation electrode 2604. The RF generator 208 may be capable of generating kilohertz AC radiofrequency waves ranging 10-100W intended to achieve permanent thermal tissue injury. The RF generator 208 may include real-time impedance monitoring, a dispersive electrode, and attendant safety circuitry. In other examples, the RF generator 208 may include micro-second or nano-second RF pulse trains intended to achieve non-thermal permanent tissue injury, sometimes described as "pulsed field ablation." Some examples may allow automatic modulation and cessation of energy based on pre-specified changes in impedance.

[0128] FIG. 27 illustrates a third example ablation catheter system 2700 in a first configuration 2701. The catheter system 2700 may be similar to the catheter system 2500 but may include multiple electrodes on each microcatheter. Thus, the catheter system 2700 includes a first microcatheter 2702. The first microcatheter 2702 may be identical to the first microcatheter 2502, other than inclusion of a plurality of electrically-isolated electrodes at the distal end, such as a first electrode 2704a, a second electrode 2704b, a third electrode 2704c, and a fourth electrode 2704d. Each of the electrodes on the first microcatheter 2702 may be surface ring electrodes. The remaining features of the first microcatheter 2702 (e g., the distal tip, openings, cross-section diameter, length, etc.) may be identical to the first microcatheter 2502 and thus the description of the first microcatheter 2502 applies to the first microcatheter 2702. The first microcatheter 2702 may be include and/or be coupled to hardware 2712 including a first electrode connector, a hemostatic valve/adapter, and an irrigation port 2712a, similar to the hardware 112, with a connection 2718 between the first electrode connector and a signal processor, similar to the one or more first connections 118.

[0129] Similarly, the catheter system 2700 includes a second microcatheter 2706. The second microcatheter 2706 may be identical to the second microcatheter 2506, other than inclusion of a plurality of electrically-isolated electrodes at the distal end, such as a fifth electrode 2706a and a sixth electrode 2706b. Each of the electrodes on the second microcatheter 2706 may be surface ring electrodes. The remaining features of the second microcatheter 2706 (e.g., the distal tip, openings, cross-section diameter, length, etc.) may be identical to the second microcatheter 2706 and thus the description of the second microcatheter 2506 applies to the second microcatheter 2706. The second microcatheter 2706 may be include and/or be coupled to hardware 2714 including a second electrode connector and/or a hemostatic valve/adapter, similar to the hardware 114, with a connection 2720 between the second electrode connector and the signal processor, similar to third connection 120. [0130] The catheter system 2700 further includes a navigation guidewire 2710 that may be identical to the navigation guidewire 110, other than inclusion of one or more additional electrodes at the distal end, in some examples. Thus, the description of the navigation guidewire 110 applies to the navigation guidewire 2710. Further, while not shown in FIG. 27, the catheter system 2700 may include an electrode connector coupled to the navigation guidewire 2710. The catheter system 2700 may include an ablation electrode, similar to the ablation electrode 2602, as well as an irrigation pump and RF generator, and may be placed into a second configuration by replacing the second microcatheter 2706 and navigation guidewire 2710 with the ablation electrode, as explained above with respect to FIG. 26.

[0131] Thus, the catheter system 2700 may include components that are the same or similar to the catheter system 2500 other than inclusion of multiple electrodes on the microcatheters and/or navigation guidewire. For example, the microcatheters and/or navigation guidewire may incorporate multiple electrically isolated insulator-conductor subassemblies for connection of multiple electrical channels to independent or multiplexed transmission line systems. The catheter system 2700 may function the same as the catheter system 2500 other than the multiple electrodes may allow for collection of local bipolar electrograms. The inclusion of unipolar electrodes as in the catheter system 2500 may lower the cost and complexity of manufacturing the catheter system 2500 relative to bipolar or multipolar electrode configurations (e.g., of the catheter system 2700), while the bipolar or multipolar electrode configurations may generate electrograms of more near- field cardiac electrical activity, for example.

[0132] Thus, the catheter system 2500 or the catheter system 2700 provide for coaxial arrangement of a 0.014" traversal and navigation guidewire (e.g., the navigation guidewire 110 or navigation guidewire 2710); a 0.014" compatible tracking microcatheter with one or more electrodes (e g., the second microcatheter 2506 or the second microcatheter 2706); an -0.035" (typically 0.035-0.038") compatible tracking/infusion microcatheter with one or more electrodes (e.g., the first microcatheter 2502 or the first microcatheter 2702); and an -0.025" diameter (typically 0.020-0.026") ablation guidewire or catheter (e.g., the ablation electrode 2602). The microcatheters may be low-profile, have lumens that closely match the device they are intended to deliver in coaxial fashion, have tapered tips to mitigate "size step-up" as they are advanced over coaxial devices/guidewires, and have braided metallic wire skeletons surrounded by electrically insulating and often lubricious polymer materials. Blood contacting surfaces of the microcatheters may be biocompatible. Polymers and/or markers of the microcatheters may be radiopaque to impart fluoroscopic conspicuity. The microcatheters may incorporate electrical transmission lines. The ring electrodes of the microcatheters may be short (l-2mm) for tracking or longer (5-10mm) for tracking and RF ablation. The microcatheters may incorporate coils or braids to impart trackability and pushability and preservation of lumen dimensions during advancement along tortuous trajectories. The cross-sectional diameters of the microcatheters as explained herein may be inner diameters that each indicate the electrically-insulated lumen has dimensional tolerances intended to allow free advancement and manipulation of a device having an outer diameter corresponding to the rated inner diameter. For example, the first microcatheter is described as having an inner diameter of 0.035 inches, which may indicate that the lumen of the first microcatheter has dimensional tolerances intended to allow the first microcatheter to slidingly receive/engage the second microcatheter and allow free advancement and manipulation of the second microcatheter within the first microcatheter, wherein the second microcatheter has an outer diameter of 0.035 inches or less. Likewise, the second microcatheter is described as having an inner diameter of 0.014 inches, which may indicate that the lumen of the second microcatheter has dimensional tolerances intended to allow the second microcatheter to slidingly receive/engage the navigation guidewire and allow free advancement and manipulation of the navigation guidewire within the second microcatheter, wherein the navigation guidewire has an outer diameter of 0.014 inches.

[0133] The second microcatheter is configured to fit tightly over the navigation guidewire, and the second microcatheter and navigation guidewire allow the larger, first microcatheter to track over the second microcatheter and navigation guidewire, so that the navigation guidewire and second microcatheter can create a path for the larger, first microcatheter to traverse the myocardium. Once positioned in the myocardium, the second microcatheter and navigation guidewire can be removed to exchange for the ablation electrode, which is larger in diameter than the navigation guidewire. This configuration may allow for the first microcatheter to have a sufficiently large diameter/lumen space to allow irrigation and facilitate introduction/navigation of the ablation electrode to the target (e.g., within the myocardium). However, other configurations are possible without departing from the scope of this disclosure. For example, as shown in FIG. 28, a fourth example ablation catheter system 2800 in a first configuration 2801 may substitute the second microcatheter with a "dilator," e.g., a tapered catheter that does not include an electrode and that occupies the space between the navigation guidewire and the first microcatheter. Thus, the catheter system 2800 may include a first microcatheter 2802, which may be identical to the first microcatheter 2502 or the first microcatheter 2702 and include at least one first electrode 2804, hardware 2812, and a connection 2818 to an EAM and/or EDEN signal processor. Accommodated within the first microcatheter 2802 is a dilator 2806 having a cross-sectional/inner diameter large enough to accommodate a navigation guidewire 2810, which may be identical to the navigation guidewire 110 or the navigation guidewire 2710 and thus be coupled to an electrode connector 2816 and connection 2822 to the signal processor. The dilator 2806 may be hollow and have a tapered tip. In some examples, the dilator 2806 may have an inner diameter in the body of the dilator 2806 that is 0.035 inches or less and may taper to an opening that has an inner diameter 0.014 inches or slightly more (e.g., 0.015 or 0.016 inches).

[0134] As shown in FIG. 29, the catheter system 2800 in a second configuration 2901 may include the dilator 2806 and navigation guidewire 2810 being replaced with an ablation electrode 2902. In the example shown in FIG. 29, the ablation electrode 2902 includes a tip 2904 (e.g., which may be the uninsulated region that serves as the electrode) of increased thickness on a relative thin shaft 2906. For example, the tip 2904 may have a diameter of 0.035 inches and a length of 1 cm, and the shaft 2906 may have a diameter of 0.014 inches. The ablation electrode 2902 may be coupled to an electrode connector 2905 that is configured to couple to a connection 2907 (e.g., to the signal processor) and to an RF generator, similar to the ablation electrode 2602.

[0135] In still further examples, the second microcatheter or dilator may be omitted altogether when the ablation electrode is configured similarly to ablation electrode 2902. In such examples, thick tip 2904 may be introduced "flush" with the first microcatheter during navigation to the target. Once the target is reached, the ablation electrode 2902 may be extended by a suitable amount (e.g., 2 cm), and the remaining thin shaft 2906 may create space to allow irrigation through the first microcatheter.

[0136] It is to be appreciated that while the catheter system 2500, the catheter system 2700, and the catheter system 2800 were described as including surface ring electrodes, other electrode configurations are possible, such as one or more of the electrodes being a spiral electrode, one or more strips, or a partial ring electrode. Further, one or more of the electrodes may include helical, feathered, dentate, and/or tapered extensions to facilitate embedding of the electrode extensions in the microcatheter shaft, as explained above. [0137] In some examples, aspects of the VINTAGE system may be assembled into a kit 3000 as shown schematically in FIG. 30. The kit 3000 may include a packaging 3002 housing the first microcatheter 2502 (including the first electrode 2504), the second microcatheter 2506 (including the second electrode 2508), the navigation guidewire 110 (including exposed conductor 111), and the ablation electrode 2602. In some examples, the packaging 3002 may be sterile packaging. In some examples, each of the first microcatheter 2502, the second microcatheter 2506, the navigation guidewire 110, and the ablation electrode 2602 may be packaged in individual, sterile packages, and the packaging 3002 may not be sterile. In some examples, the kit 3000 may include the first microcatheter 2702 instead of the first microcatheter 2502, the second microcatheter 2706 instead of the second microcatheter 2506, and/or the navigation guidewire 2710 instead of the navigation guidewire 110. In some examples, additionally or alternatively, the kit 3000 may include the dilator 2806 instead of the second microcatheter 2506. In still further examples, additionally or alternatively, the kit 3000 may include the ablation electrode 2902 instead of the ablation electrode 2602. In some examples, additionally or alternatively, the kit 3000 may not include the second microcatheter 2506, the second microcatheter 2706, or the dilator 2806. Rather, as shown by example kit 3100 of FIG. 31, the kit 3100 may include the first microcatheter 2502, the navigation guidewire 110, and the ablation electrode 2902, housed in a packaging 3102 (which may be sterile, or alternatively, each of the first microcatheter 2502, the navigation guidewire 110, and the ablation electrode 2902 may be packaged in individual sterile packaging and packaging 3102 is not necessarily sterile).

[0138] In some examples, the kit 3000 may include the components of the second kit 1201, including the packaging 1204 housing the accessor catheter 304 (optionally including the first electrode 308 and the second electrode 310, one or more or each or none of which may include helical, feathered, dentate, and/or tapered extensions) and the anchor system (including the anchor shaft 306, the myocardial engagement component 312, and hinge mechanism 314), either as separate components or with the anchor system integrated in the accessor catheter 304. In other examples, the kit 3000 may include other components for delivering the ablation catheter system, such as a curved or deflectable guiding sheath, a curved or deflectable guiding catheter, and/or an anchor guidewire. Further, in some examples, the kit 3000 may include one or more electrode connectors 3006. In still further examples, the kit 3000 may include connectors, signal wires, and/or other components for connecting the first microcatheter, the second microcatheter, the navigation guidewire, and the ablation electrode to an EAM and/or EDEN signal processor and/or for connecting the ablation guidewire to the RF generator.

[0139] In some examples, the kit 3000 may include multiple first microcatheters, second microcatheters, navigation guidewires, and ablation electrodes, such as 5, 10, 25, 50, 100, or more of each of the first microcatheter, the second microcatheter, the navigation guidewire, and the ablation electrode. In such examples, each individual component (e.g., each first microcatheter, each second microcatheter, etc.) may be packaged in a separate sterile packaging and all housed within packaging 3002. Alternatively, one of each of the first microcatheter, the second microcatheter, the navigation guidewire, and the ablation electrode may be packaged together in a common, sterile packaging to form a sub-kit, and a plurality of sub-kits (e.g., 5, 10, 25, 50, 100, etc.) may be packaged in packaging 3002. In examples where the kit 3000 includes the components of the second kit 1201 or the guiding sheath, the guiding catheter, the anchor guidewire, and/or the one or more electrode connectors 3006, the kit 3000 may include multiple of the components of the second kit, or multiple guiding sheaths, guiding catheters, and/or anchor guidewires (e.g., the same number as the number of first microcatheters), as well as multiple sets of the one or more electrode connectors 3006, packaged similarly to the first microcatheters, second microcatheters, navigation guidewires, and ablation electrodes (e.g., individually or in sub-kits).

[0140] FIGS. 1-10 and 13-31 show example configurations with relative positioning of the various components. If shown directly contacting each other, or directly coupled, then such elements may be referred to as directly contacting or directly coupled, respectively, at least in one example. Similarly, elements shown contiguous or adjacent to one another may be contiguous or adjacent to each other, respectively, at least in one example. As an example, components laying in face-sharing contact with each other may be referred to as in face-sharing contact. As another example, elements positioned apart from each other with only a space there-between and no other components may be referred to as such, in at least one example. As yet another example, elements shown above/below one another, at opposite sides to one another, or to the 1 eft/right of one another may be referred to as such, relative to one another. Further, as shown in the figures, a topmost element or point of element may be referred to as a “top” of the component and a bottommost element or point of the element may be referred to as a “bottom” of the component, in at least one example. As used herein, top/bottom, upper/lower, above/below, may be relative to a vertical axis of the figures and used to describe positioning of elements of the figures relative to one another. As such, elements shown above other elements are positioned vertically above the other elements, in one example. As yet another example, shapes of the elements depicted within the figures may be referred to as having those shapes (e.g., such as being circular, straight, planar, curved, rounded, chamfered, angled, or the like). Further, elements shown intersecting one another may be referred to as intersecting elements or intersecting one another, in at least one example. Further still, an element shown within another element or shown outside of another element may be referred as such, in one example.

[0141] The disclosure also provides support for a microcatheter for intramyocardial navigation and ablation, comprising: a flexible catheter tube having a rounded or tapered nosecone, and a conductive ablation electrode positioned near a distal tip of the catheter tube, the ablation electrode including one or more openings to facilitate delivery of fluid out of the ablation electrode. In a first example of the system, the catheter tube and ablation electrode form an inner lumen configured to accommodate a navigation guidewire, the inner lumen having a first cross-sectional diameter that is larger than a second cross-sectional diameter of the navigation guidewire to allow the delivery of fluid through the inner lumen and out of the one or more openings of the ablation electrode. In a second example of the microcatheter, optionally including the first example, the catheter tube includes the tapered nosecone that tapers in cross-sectional diameter near and at the distal tip, such that a third cross-sectional diameter at the distal tip substantially matches the second cross-sectional diameter. In a third example of the microcatheter, optionally including one or both of the first and second examples, the microcatheter further comprises: one or more mapping electrodes coupled to the catheter tube. In a fourth example of the microcatheter, optionally including one or more or each of the first through third examples, the one or more mapping electrodes includes a first mapping electrode coupled between the ablation electrode and the distal tip of the catheter tube. In a fifth example of the microcatheter, optionally including one or more or each of the first through fourth examples, the first mapping electrode comprises a surface ring electrode, a spiral electrode, one or more strips, or a partial ring electrode. In a sixth example of the microcatheter, optionally including one or more or each of the first through fifth examples, the first mapping electrode includes a first extension at a first end of the first mapping electrode and a second extension at a second end of the first mapping electrode, wherein the first extension is fully or partially embedded in a first section of the catheter tube and the second extension is fully or partially embedded in a second section of the catheter tube, wherein the first extension and the second extension each comprises a helical, feathered, dentate, and/or tapered segment. In a seventh example of the microcatheter, optionally including one or more or each of the first through sixth examples, the microcatheter further comprises: a hub at a proximal end of the catheter tube, the hub including an irrigation port and a connector configured to couple the ablation electrode to a radiofrequency (RF) generator. In an eighth example of the microcatheter, optionally including one or more or each of the first through seventh examples, the one or more openings include a plurality of fenestrations. In a ninth example of the microcatheter, optionally including one or more or each of the first through eighth examples: the ablation electrode includes one or more tines, each tine shaped and sized to fit in a respective opening of the one or more openings when in a first position and configured to move outward to a second position to expose the respective opening, the ablation electrode includes one or more first electrode strips, each first electrode strip configured to extend along a longitudinal axis of the microcatheter in a first position and configured to bend outward to a second position to expose the one or more openings, the ablation electrode includes one or more second electrode strips, each second electrode strip winding at least partially around a longitudinal axis of the microcatheter, each second electrode strip configured to bend outward from a first position to a second position to expose the one or more openings, or the one or more openings of the ablation electrode include a continuous helical opening formed by an electrode strip that winds around a longitudinal axis of the microcatheter in a helical fashion. In a tenth example of the microcatheter, optionally including one or more or each of the first through ninth examples, the one or more openings of the ablation electrode are openings formed in a body of the ablation electrode, the body extending around each opening such that the ablation electrode is electrically continuous from a distal end of the ablation electrode to a proximal end of the ablation electrode.

[0142] This disclosure also provides support for a system including the microcatheter provided in the above paragraph (e.g., (of one or more or each of the first through tenth examples) and a navigation guidewire configured to be slidingly received by the microcatheter. In a first example of the system, the navigation guidewire includes an insulated region and an uninsulated region, and wherein the navigation guidewire has a smaller diameter than a diameter of the catheter tube. In a second example of the system, optionally including the first example, the system further comprises: an accessor catheter including a shaft, the shaft including one or more lumens, the one or more lumens sized to accommodate the microcatheter and an anchor system. [0143] The disclosure also provides support for a method for an ablation procedure, comprising: navigating an ablation microcatheter to an ablation target via a navigation guidewire, the navigation guidewire housed within the ablation microcatheter, the ablation microcatheter including an ablation electrode comprising one or more openings, irrigating the ablation target with an electrolyte via the one or more openings of the ablation microcatheter, and ablating the ablation target with radiofrequency (RF) energy via the ablation electrode while continuing to irrigate the ablation target. In a first example of the method, navigating the ablation microcatheter to the ablation target comprises navigating the ablation microcatheter to the ablation target based on electrograms detected by one or more electrodes positioned on the navigation guidewire and/or the ablation microcatheter. In a second example of the method, optionally including the first example, navigating the ablation microcatheter to the ablation target comprises navigating the ablation microcatheter to the ablation target based on electromagnetic fields encoding geometric position and time from an electroanatomic mapping system detected by one or more electrodes positioned on the navigation guidewire and/or the ablation microcatheter. In a third example of the method, optionally including one or both of the first and second examples, ablating the ablation target with RF energy via the ablation electrode comprises activating an RF generator coupled to the ablation electrode. In a fourth example of the method, optionally including one or more or each of the first through third examples, the ablation target is an intramyocardial ablation target of a non-human or human patient. In a fifth example of the method, optionally including one or more or each of the first through fourth examples, navigating the ablation microcatheter to the ablation target via the navigation guidewire comprises: navigating the ablation microcatheter and navigation guidewire to an entry point on a myocardial surface with an accessor catheter, deploying a myocardial engagement component of an anchor system from the accessor catheter into myocardium at the entry point, extending the navigation guidewire out of the accessor catheter and to the ablation target in the myocardium and tracking the ablation microcatheter over the navigation guidewire and to the ablation target.

[0144] The disclosure also provides support for a kit for intramyocardial navigation and ablation, comprising: a first microcatheter including a first electrode, a navigation guidewire including a second electrode and configured to be slidingly received by the first microcatheter, and an ablation electrode configured to be slidingly received by the first microcatheter. In a first example of the kit, the navigation guidewire includes an insulated region and an uninsulated region, wherein the uninsulated region includes the second electrode, and wherein the first electrode is a surface ring electrode positioned adjacent a distal tip of the first microcatheter. In a second example of the kit, optionally including the first example, the first microcatheter and/or the navigation guidewire includes one or more additional electrodes. In a third example of the kit, optionally including one or both of the first and second examples, the navigation guidewire has a smaller diameter than a diameter of the ablation electrode. In a fourth example of the kit, optionally including one or more or each of the first through third examples, the diameter of the ablation electrode is at least 0.025 inches (0.635 mm). In a fifth example of the kit, optionally including one or more or each of the first through fourth examples, the first microcatheter includes an irrigation port and a first electrode connector. In a sixth example of the kit, optionally including one or more or each of the first through fifth examples, the navigation guidewire includes a second electrode connector. In a seventh example of the kit, optionally including one or more or each of the first through sixth examples, the ablation electrode comprises an ablation guidewire, and wherein the ablation guidewire is coated in an insulating coating other than at a distal tip and a proximate tip of the ablation guidewire, wherein the distal tip forms the ablation electrode. In an eighth example of the kit, optionally including one or more or each of the first through seventh examples, the ablation electrode has a first diameter that is larger than a second dimeter of the remaining portion of the ablation guidewire. In a ninth example of the kit, optionally including one or more or each of the first through eighth examples, the kit further comprises: a second microcatheter including a third electrode, wherein the first microcatheter has a first diameter and the second microcatheter has a second diameter, the second diameter smaller than the first diameter, and wherein the navigation guidewire is configured to be slidingly received by the second microcatheter and each of the second microcatheter and the navigation guidewire is configured to be slidingly received by the first microcatheter. In a tenth example of the kit, optionally including one or more or each of the first through ninth examples, the second microcatheter includes a third electrode connector. In an eleventh example of the kit, optionally including one or more or each of the first through tenth examples, the system further comprises: a dilator, wherein the first microcatheter has a first diameter and the dilator has a second diameter, the second diameter smaller than the first diameter, and wherein the navigation guidewire is configured to be slidingly received by the dilator and each of the dilator and the navigation guidewire is configured to be slidingly received by the first microcatheter. In a twelfth example of the kit, optionally including one or more or each of the first through eleventh examples, the kit further comprises: an anchor guidewire. In a thirteenth example of the kit, optionally including one or more or each of the first through twelfth examples, the kit further comprises: a guiding sheath and/or a guiding catheter.

[0145] The disclosure also provides support for a method for an ablation procedure, comprising: navigating a first microcatheter to an ablation target via a navigation guidewire, the navigation guidewire housed within the first microcatheter, removing the navigation guidewire from the first microcatheter, navigating an ablation electrode to the ablation target via the first microcatheter, irrigating the ablation target with an electrolyte via the first microcatheter, and ablating the ablation target with radiofrequency (RF) energy via the ablation electrode while continuing to irrigate the ablation target. In a first example of the method, navigating the first microcatheter to the ablation target via the navigation guidewire comprises navigating the first microcatheter to the ablation target via the navigation guidewire and a second microcatheter or dilator, wherein the second microcatheter or dilator is housed within the first microcatheter and the navigation guidewire is housed within the second microcatheter or dilator. In a second example of the method, optionally including the first example, removing the navigation guidewire from the first microcatheter includes removing the navigation guidewire and the second microcatheter or the dilator from the first microcatheter. In a third example of the method, optionally including one or both of the first and second examples, navigating the first microcatheter to the ablation target comprises navigating the first microcatheter to the ablation target based on electrograms generated by one or more electrodes positioned on the navigation guidewire and/or the first microcatheter, and wherein navigating the ablation electrode to the ablation target via the first microcatheter comprises navigating the ablation electrode to the ablation target based on electrograms generated by the ablation electrode. In a fourth example of the method, optionally including one or more or each of the first through third examples, ablating the ablation target with RF energy via the ablation electrode comprises activating an RF generator coupled to the ablation electrode at an initial power of 20W. In a fifth example of the method, optionally including one or more or each of the first through fourth examples, the ablation target is an intramyocardial ablation target of a non-human or human patient.

[0146] The disclosure also provides support for a microcatheter for intramyocardial navigation and ablation, comprising: a flexible catheter tube having a rounded or tapered nosecone, and a conductive ablation electrode positioned near a distal tip of the catheter tube, the ablation electrode including one or more openings to facilitate delivery of fluid out of the ablation electrode. In a first example of the microcatheter, the catheter tube and ablation electrode form an inner lumen configured to accommodate a navigation guidewire, the inner lumen having a first cross-sectional diameter that is larger than a second cross-sectional diameter of the navigation guidewire to allow the delivery of fluid through the inner lumen and out of the one or more openings of the ablation electrode. In a second example of the microcatheter, optionally including the first example, the catheter tube includes the tapered nosecone that tapers in cross-sectional diameter near and at the distal tip, such that a third cross-sectional diameter at the distal tip substantially matches the second cross-sectional diameter. In a third example of the microcatheter, optionally including one or both of the first and second examples, the ablation electrode comprises a first extension at a first end of the ablation electrode and a second extension at a second end of the ablation electrode, wherein the first extension is fully or partially embedded in a first section of the catheter tube and the second extension is fully or partially embedded in a second section of the catheter tube, wherein the first extension and the second extension each comprises a helical, feathered, dentate, and/or tapered segment. In a fourth example of the microcatheter, optionally including one or more or each of the first through third examples, the microcatheter further comprises: one or more mapping electrodes coupled to the catheter tube. In a fifth example of the microcatheter, optionally including one or more or each of the first through fourth examples, the one or more mapping electrodes includes a first mapping electrode coupled between the ablation electrode and the distal tip of the catheter tube. In a sixth example of the microcatheter, optionally including one or more or each of the first through fifth examples, the first mapping electrode comprises a surface ring electrode, a spiral electrode, one or more strips, or a partial ring electrode. In a seventh example of the microcatheter, optionally including one or more or each of the first through sixth examples, the first mapping electrode includes a first extension at a first end of the first mapping electrode and a second extension at a second end of the first mapping electrode, wherein the first extension is fully or partially embedded in a first section of the catheter tube and the second extension is fully or partially embedded in a second section of the catheter tube, wherein the first extension and the second extension each comprises a helical, feathered, dentate, and/or tapered segment. In an eighth example of the microcatheter, optionally including one or more or each of the first through seventh examples, the one or more mapping electrodes further includes a second mapping electrode positioned on a proximal side of the ablation electrode. In a ninth example of the microcatheter, optionally including one or more or each of the first through eighth examples, each mapping electrode is comprised of copper, stainless steel alloy, platinum-iridium alloy, titanium, or cobaltchromium, with or without gold-plating. In a tenth example of the microcatheter, optionally including one or more or each of the first through ninth examples, the catheter tube tapers in cross- sectional diameter near and at the distal tip to form the tapered nosecone. In an eleventh example of the system, optionally including one or more or each of the first through tenth examples, the microcatheter further comprises: a hub at a proximal end of the catheter tube, the hub including an irrigation port and a connector configured to couple the ablation electrode to a radiofrequency (RF) generator. In a twelfth example of the microcatheter, optionally including one or more or each of the first through eleventh examples, the one or more openings include a plurality of fenestrations. In a thirteenth example of the microcatheter, optionally including one or more or each of the first through twelfth examples, fenestrations of the ablation electrode are evenly distributed around the ablation electrode. In a fourteenth example of the microcatheter, optionally including one or more or each of the first through thirteenth examples, each fenestration of the ablation electrode has a circular shape. In a fifteenth example of the microcatheter, optionally including one or more or each of the first through fourteenth examples, the ablation electrode includes one or more tines, each tine shaped and sized to fit in a respective opening of the one or more openings when in a first position and configured to move outward to a second position to expose the respective opening. In a sixteenth example of the microcatheter, optionally including one or more or each of the first through fifteenth examples, the ablation electrode includes one or more electrode strips, each electrode strip configured to extend along a longitudinal axis of the microcatheter in a first position and configured to bend outward to a second position to expose the one or more openings. In a seventeenth example of the microcatheter, optionally including one or more or each of the first through sixteenth examples, the ablation electrode includes one or more electrode strips, each electrode strip winding at least partially around a longitudinal axis of the microcatheter, each electrode strip configured to bend outward from a first position to a second position to expose the one or more openings. In an eighteenth example of the microcatheter, optionally including one or more or each of the first through seventeenth examples, the one or more openings of the ablation electrode include a continuous helical opening formed by an electrode strip that winds around a longitudinal axis of the microcatheter in a helical fashion. In a nineteenth example of the microcatheter, optionally including one or more or each of the first through eighteenth examples, the one or more openings of the ablation electrode are openings formed in a body of the ablation electrode, the body extending around each opening such that the ablation electrode is electrically continuous from a distal end of the ablation electrode to a proximal end of the ablation electrode. In a twentieth example of the microcatheter, optionally including one or more or each of the first through nineteenth examples, the catheter tube includes an opening at the distal tip. In a twenty- first example of the microcatheter, optionally including one or more or each of the first through twentieth examples, the catheter tube includes one or more longitudinal slots, grooves, and/or channels on an inner surface of the catheter tube. In a twenty-second example of the microcatheter, optionally including one or more or each of the first through twenty-first examples, the catheter tube includes one or more transmission lines, including a first transmission line electrically coupled to the ablation electrode. In a twenty-third example of the microcatheter, optionally including one or more or each of the first through twenty-second examples, the catheter tube includes embedded metallic or non-metallic braiding or coils that are continuous or segmented and electrically uninsulated or insulated, wherein individually insulated braiding wires can be used as transmission lines. In a twenty-fourth example of the microcatheter, optionally including one or more or each of the first through twenty-third examples, the catheter tube includes a lining that extends along and is in face-sharing contact with the ablation electrode. In a twenty-fifth example of the microcatheter, optionally including one or more or each of the first through twenty-fourth examples, the ablation electrode is comprised of one or more heat-resistant, biocompatible, low impedance, electrically conductive materials. In a twenty-sixth example of the microcatheter, optionally including one or more or each of the first through twenty-fifth examples, the ablation electrode is comprised of copper, stainless steel alloy, platinum-iridium alloy, titanium, or cobaltchromium, with or without gold-plating.

[0147] This disclosure also provides support for a system comprising the microcatheter as provided above (e.g., according to one or more or each of the first through twenty-sixth examples provided above) and a navigation guidewire configured to be slidingly received by the microcatheter. In first example of the system, the navigation guidewire includes an insulated region and an uninsulated region. In a second of the system, optionally including the first example, the navigation guidewire has a smaller diameter than a diameter of the catheter tube. In a third example of the system, optionally including one or more or each of the first and second examples, the kit includes one or more electrode connectors. In a fourth example of the system, optionally including one or more or each of the first through third examples, the kit includes one or more of a guiding sheath, a guiding catheter, and an anchor guidewire.

[0148] The disclosure also provides support for a method for an ablation procedure, comprising: navigating an ablation microcatheter to an ablation target via a navigation guidewire, the navigation guidewire housed within the ablation microcatheter, the ablation microcatheter including an ablation electrode comprising one or more openings, irrigating the ablation target with an electrolyte via the one or more openings of the ablation microcatheter, and ablating the ablation target with radiofrequency (RF) energy via the ablation electrode while continuing to irrigate the ablation target. In a first example of the method, navigating the ablation microcatheter to the ablation target comprises navigating the ablation microcatheter to the ablation target based on electrograms detected by one or more electrodes positioned on the navigation guidewire and/or the ablation microcatheter. In a second example of the method, optionally including the first example, navigating the ablation microcatheter to the ablation target comprises navigating the ablation microcatheter to the ablation target based on electromagnetic fields encoding geometric position and time from an electroanatomic mapping system detected by one or more electrodes positioned on the navigation guidewire and/or the ablation microcatheter. In a third example of the method, optionally including one or both of the first and second examples, ablating the ablation target with RF energy via the ablation electrode comprises activating an RF generator coupled to the ablation electrode. In a fourth example of the method, optionally including one or more or each of the first through third examples, the ablation target is an intramyocardial ablation target of a non-human or human patient.

[0149] The disclosure also provides support for a microcatheter, comprising: a shaft, and an electrode embedded onto the shaft, the electrode comprising an electrode segment, a first extension extending outward from the electrode segment on a first side of the electrode segment, and a second extension extending outward from the electrode segment on a second side of the electrode segment, wherein the first extension and the second extension are each helical, feathered, dentate, and/or tapered. In a first example of the microcatheter, the first extension is partially or fully embedded in the shaft, the second extension is fully or partially embedded in the shaft, and an outer surface of the electrode segment is exposed to ambient. [0150] The disclosure also provides support for a guiding catheter system for intramyocardial navigation and ablation, comprising: an accessor catheter including a shaft, the shaft including one or more lumens, the one or more lumens sized to accommodate an effector configured to perform intramyocardial navigation and an anchor system. In a first example of the system, the system further comprises: one or more mapping electrodes coupled to the shaft at and/or near a distal tip of the shaft. In a second example of the system, optionally including the first example, the one or more mapping electrodes are ring electrodes, partial ring electrodes, coils, or strips. In a third example of the system, optionally including one or both of the first and second examples, the shaft includes a bend near a distal tip of the shaft. In a fourth example of the system, optionally including one or more or each of the first through third examples, the shaft includes a deflectable portion near a distal tip of the shaft and configured to adjust a radius of curvature of the shaft. In a fifth example of the system, optionally including one or more or each of the first through fourth examples, the system further comprises: an outer catheter having an adjustable deflection radius, the accessor catheter coaxially arranged in the outer catheter. In a sixth example of the system, optionally including one or more or each of the first through fifth examples, the system further comprises: a handle coupled to the shaft and the outer catheter at a proximal end of the shaft and the outer catheter, the handle including a first actuator and a second actuator, the first actuator configured to adjust the deflection radius of the outer catheter and the second actuator configured to adjust a linear position of the shaft relative to the outer catheter. In a seventh example of the system, optionally including one or more or each of the first through sixth examples, the anchor system comprises an anchor shaft coupled to a myocardial engagement component. In a eighth example of the system, optionally including one or more or each of the first through seventh examples, the myocardial engagement component comprises a set of anchor prongs. In a ninth example of the system, optionally including one or more or each of the first through eighth examples, the anchor shaft is coupled to the myocardial engagement component via a hinge mechanism. In a tenth example of the system, optionally including one or more or each of the first through ninth examples, the one or more lumens of the shaft include two non-concentric lumens, the two non-concentric lumens including a first lumen to accommodate the effector and a second lumen to accommodate the anchor system.

[0151] The disclosure also provides support for a kit for intramyocardial navigation and ablation, comprising: an accessor catheter including a shaft, the shaft including one or more lumens, the one or more lumens sized to accommodate an effector configured to perform intramyocardial navigation and an anchor system, and the anchor system. In a first example of the kit, the kit further comprises: the effector. In a second example of the kit, optionally including the first example, the effector comprises an ablation microcatheter including an ablation electrode, the ablation electrode including one or more openings. In a third example of the kit, optionally including one or both of the first and second examples, the kit further comprises: a navigation guidewire, wherein the navigation guidewire is configured to be slidingly received by an inner lumen of the ablation microcatheter. In a fourth example of the kit, optionally including one or more or each of the first through third examples, the ablation microcatheter includes one or more mapping electrodes. In a fifth example of the kit, optionally including one or more or each of the first through fourth examples, the navigation guidewire has a smaller diameter than a diameter of the inner lumen of the ablation microcatheter. In a sixth example of the kit, optionally including one or more or each of the first through fifth examples, the ablation microcatheter includes an irrigation port and a radiofrequency (RF) connector. In a seventh example of the kit, optionally including one or more or each of the first through sixth examples, the shaft includes a bend near a distal tip of the shaft. In an eighth example of the kit, optionally including one or more or each of the first through seventh examples, the shaft includes a deflectable portion near a distal tip of the shaft and configured to adjust a radius of curvature of the shaft. In a ninth example of the kit, optionally including one or more or each of the first through eighth examples, the kit further comprises: an outer catheter, wherein the accessor catheter is configured to be slidingly received by the outer catheter. In a tenth example of the kit, optionally including one or more or each of the first through ninth examples, the outer catheter includes a deflectable portion near a distal tip of the outer catheter and configured to adjust a radius of curvature of the outer catheter. In an eleventh example of the kit, optionally including one or more or each of the first through tenth examples, the anchor system includes an anchor shaft coupled to a myocardial engagement component via a hinge mechanism.

[0152] The disclosure also provides support for a method for an ablation procedure, comprising: navigating an effector to an entry point on a myocardial surface with an accessor catheter, deploying a myocardial engagement component of an anchor system from the accessor catheter into myocardium at the entry point, extending the effector out of the accessor catheter and to an ablation target in the myocardium, and ablating the ablation target with radiofrequency (RF) energy via the effector. In a first example of the method, navigating the effector to the entry point on the myocardial surface with the accessor catheter comprises adjusting a deflection angle and/or radius of curvature and/or pivot point of the accessor catheter to position at a distal tip of the accessor catheter orthogonal to the myocardial surface. In a second example of the method, optionally including the first example, navigating the effector to the entry point on the myocardial surface with the accessor catheter comprises navigating the effector to the entry point based on electromagnetic fields encoding geometric position and time from an electroanatomic mapping system detected by one or more electrodes positioned on the accessor catheter. In a third example of the method, optionally including one or both of the first and second examples, the effector includes an ablation microcatheter comprising a conductive ablation electrode having one or more openings, and wherein ablating the ablation target includes irrigating the ablation target with an electrolyte via the one or more openings. In a fourth example of the method, optionally including one or more or each of the first through third examples, the method further comprises: navigating the ablation microcatheter to the ablation target based on electrograms generated by one or more electrodes positioned on the ablation microcatheter. In a fifth example of the method, optionally including one or more or each of the first through fourth examples, ablating the ablation target with RF energy via the effector comprises activating an RF generator coupled to the conductive ablation electrode.

[0153] As used herein, an element or step recited in the singular and preceded with the word “a” or “an” should be understood as not excluding plural of said elements or steps, unless such exclusion is explicitly stated. Furthermore, references to “one embodiment” of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments “comprising,” “including,” or “having” an element or a plurality of elements having a particular property may include additional such elements not having that property. The terms “including” and “in which” are used as the plain-language equivalents of the respective terms “comprising” and “wherein.” Moreover, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements or a particular positional order on their objects.

[0154] This written description uses examples to disclose the invention, including the best mode, and also to enable a person of ordinary skill in the relevant art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those of ordinary skill in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

CLAIMS:

1. A microcatheter for intramyocardial navigation and ablation, comprising: a flexible catheter tube having a rounded or tapered nosecone; and a conductive ablation electrode positioned near a distal tip of the catheter tube, the ablation electrode including one or more openings to facilitate delivery of fluid out of the ablation electrode.

2. The microcatheter of claim 1, wherein the catheter tube and ablation electrode form an inner lumen configured to accommodate a navigation guidewire, the inner lumen having a first cross-sectional diameter that is larger than a second cross-sectional diameter of the navigation guidewire to allow the delivery of fluid through the inner lumen and out of the one or more openings of the ablation electrode.

3. The microcatheter of claim 2, wherein the catheter tube includes the tapered nosecone that tapers in cross-sectional diameter near and at the distal tip, such that a third cross-sectional diameter at the distal tip substantially matches the second cross-sectional diameter.

4. The microcatheter of any one of claims 1-3, further comprising one or more mapping electrodes coupled to the catheter tube.

5. The microcatheter of claim 4, wherein the one or more mapping electrodes includes a first mapping electrode coupled between the ablation electrode and the distal tip of the catheter tube.

6. The microcatheter of claim 5, wherein the first mapping electrode comprises a surface ring electrode, a spiral electrode, one or more strips, or a partial ring electrode.

7. The microcatheter of claim 5 or 6, wherein the first mapping electrode includes a first extension at a first end of the first mapping electrode and a second extension at a second end of the first mapping electrode, wherein the first extension is fully or partially embedded in a first section of the catheter tube and the second extension is fully or partially embedded in a second section of the catheter tube, wherein the first extension and the second extension each comprises a helical, feathered, dentate, and/or tapered segment.

8. The microcatheter of any one of claims 1-7, further comprising a hub at a proximal end of the catheter tube, the hub including an irrigation port and a connector configured to couple the ablation electrode to a radiofrequency (RF) generator.

9. The microcatheter of any one of claims 1-8, wherein the one or more openings include a plurality of fenestrations.

10. The microcatheter of any one of claims 1-8, wherein: the ablation electrode includes one or more tines, each tine shaped and sized to fit in a respective opening of the one or more openings when in a first position and configured to move outward to a second position to expose the respective opening; the ablation electrode includes one or more first electrode strips, each first electrode strip configured to extend along a longitudinal axis of the microcatheter in a first position and configured to bend outward to a second position to expose the one or more openings, the ablation electrode includes one or more second electrode strips, each second electrode strip winding at least partially around a longitudinal axis of the microcatheter, each second electrode strip configured to bend outward from a first position to a second position to expose the one or more openings; or the one or more openings of the ablation electrode include a continuous helical opening formed by an electrode strip that winds around a longitudinal axis of the microcatheter in a helical fashion.

11. The microcatheter of any one of claims 1-10, wherein the one or more openings of the ablation electrode are openings formed in a body of the ablation electrode, the body extending around each opening such that the ablation electrode is electrically continuous from a distal end of the ablation electrode to a proximal end of the ablation electrode.

12. A system for intramyocardial navigation and ablation, comprising: the microcatheter of any one of claims 1-11; and a navigation guidewire configured to be slidingly received by the microcatheter.

13. The system of claim 12, wherein the navigation guidewire includes an insulated region and an uninsulated region, and wherein the navigation guidewire has a smaller diameter than a diameter of the catheter tube.

14. The system of claim 12 or 13, further comprising an accessor catheter including a shaft, the shaft including one or more lumens, the one or more lumens sized to accommodate the microcatheter and an anchor system.

15. A method for an ablation procedure, comprising: navigating an ablation microcatheter to an ablation target via a navigation guidewire, the navigation guidewire housed within the ablation microcatheter, the ablation microcatheter including an ablation electrode comprising one or more openings; irrigating the ablation target with an electrolyte via the one or more openings of the ablation microcatheter; and ablating the ablation target with radiofrequency (RF) energy via the ablation electrode while continuing to irrigate the ablation target.

16. The method of claim 15, wherein navigating the ablation microcatheter to the ablation target comprises navigating the ablation microcatheter to the ablation target based on electrograms detected by one or more electrodes positioned on the navigation guidewire and/or the ablation microcatheter.

17. The method of claim 15 or 16, wherein navigating the ablation microcatheter to the ablation target comprises navigating the ablation microcatheter to the ablation target based on electromagnetic fields encoding geometric position and time from an electroanatomic mapping system detected by one or more electrodes positioned on the navigation guidewire and/or the ablation microcatheter.

18. The method of any one of claims 15-17, wherein ablating the ablation target with RF energy via the ablation electrode comprises activating an RF generator coupled to the ablation electrode.

19. The method of any one of claims 15-18, wherein the ablation target is an intramyocardial ablation target of a non-human or human patient.

20. The method of any one of claims 15-19, wherein navigating the ablation microcatheter to the ablation target via the navigation guidewire comprises: navigating the ablation microcatheter and navigation guidewire to an entry point on a myocardial surface with an accessor catheter; deploying a myocardial engagement component of an anchor system from the accessor catheter into myocardium at the entry point; extending the navigation guidewire out of the accessor catheter and to the ablation target in the myocardium and tracking the ablation microcatheter over the navigation guidewire and to the ablation target.