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WO2025193517A1 - Détection de mouvement de cathéter d'ablation sur la base de valeurs d'impédance - Google Patents

Détection de mouvement de cathéter d'ablation sur la base de valeurs d'impédance

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Publication number
WO2025193517A1
WO2025193517A1 PCT/US2025/018807 US2025018807W WO2025193517A1 WO 2025193517 A1 WO2025193517 A1 WO 2025193517A1 US 2025018807 W US2025018807 W US 2025018807W WO 2025193517 A1 WO2025193517 A1 WO 2025193517A1
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WO
WIPO (PCT)
Prior art keywords
electrode
electrodes
measured impedance
measurement
impedance values
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/US2025/018807
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English (en)
Inventor
Steffen HOLZINGER
Dorin Panescu
Laura BOEHMERT
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CRC EP Inc.
Original Assignee
CRC EP Inc.
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Filing date
Publication date
Application filed by CRC EP Inc. filed Critical CRC EP Inc.
Publication of WO2025193517A1 publication Critical patent/WO2025193517A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B18/04—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating
    • A61B18/12—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by passing a current through the tissue to be heated, e.g. high-frequency current
    • A61B18/14—Probes or electrodes therefor
    • A61B18/1492—Probes or electrodes therefor having a flexible, catheter-like structure, e.g. for heart ablation
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B18/04—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating
    • A61B18/12—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by passing a current through the tissue to be heated, e.g. high-frequency current
    • A61B18/1206—Generators therefor
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B2018/00053—Mechanical features of the instrument of device
    • A61B2018/0016—Energy applicators arranged in a two- or three dimensional array
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B2018/00636—Sensing and controlling the application of energy
    • A61B2018/00773—Sensed parameters
    • A61B2018/00875—Resistance or impedance
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B18/04—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating
    • A61B18/12—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by passing a current through the tissue to be heated, e.g. high-frequency current
    • A61B18/14—Probes or electrodes therefor
    • A61B2018/1467—Probes or electrodes therefor using more than two electrodes on a single probe

Definitions

  • the present invention relates to embodiments of a system comprising an ablation catheter suitable for pulsed-field ablation (PF A), a method for assessment of positions and/or configuration of electrodes of such ablation catheter, a respective computer program product and a respective computer readable data carrier.
  • PF A pulsed-field ablation
  • the present invention relates to embodiments of a system comprising a PFA catheter, a measurement unit and an electronic control unit, whereby the system may be used for safely performing cardiac ablation procedures, such as, but not limited to, pulmonary vein isolation (PVI), persistent atrial fibrillation ablation, ventricular tachycardiac ablation.
  • the catheter comprises multiple electrodes and delivers pulsed-field energy to achieve irreversible electroporation of cardiac tissue.
  • ablation catheters for PVI procedures in the therapy of atrial fibrillation (AF) patients.
  • the pulmonary veins (PV) are electrically isolated from the left atrium by creating contiguous circumferential ablation lesions around the pulmonary vein ostium (PVO) or around their antrum.
  • Ablation catheters may be used to deliver therapy to other tissues, such as, but not limited to: ventricles, right atrium, the body of the left atrium, etc.
  • other organs may be treated via use of catheters: lungs, liver, kidneys, etc.
  • ablation catheters are available including single point tip electrode catheters, circular multi-electrode loop catheters, and balloon-based ablation catheters using different energy sources. They all lack the ability of producing the required ablations, which safely electrically isolate the arrhythmogenic triggers from the rest of the heart chamber, in a ‘one-shot’ modality, without further repositioning, rotating or moving of the catheter. It is one goal of ablation catheter development to provide catheters and systems which safely achieve a ‘moat’ of electrical isolation in one shot.
  • the concept of a moat of electrical isolation is defined as region of cardiac tissue that surrounds the arrhythmogenic trigger and prevents its propagation to the rest of the heart chamber.
  • Pulsed-field ablation if designed appropriately, may have the advantage of creating these conduction block/electrical isolation moats in one shot, safely without or with minimal collateral tissue damage.
  • An ablation catheter that is particularly well suited for PFA treatment of a patient's tissue, for example for a PVI procedure at a patient's heart tissue or vein tissue, comprises an elongated catheter shaft and an ablation portion being arranged at a distal end of the catheter shaft with a plurality of electrodes accommodated along the ablation portion, wherein the ablation portion comprises at least two loop sections forming a three-dimensional spiral or similar flexible structures that allow one electrodes to move relative to another.
  • PFA uses high-intensity electrical fields. Under some circumstances of the treatment the distance of two electrodes may become so small that an electromagnetic field intensity is sufficiently high to ionize the medium between these electrodes. In such case, arcing develops, in particular, if bipolar PFA is used. This means that for catheters with open loops or flexible splines, some electrode pairs can approach such that the risk for arcing is increased. Arcing presents an increased level of danger to patients, as it results in unintended tissue damage.
  • the high temperatures of arcs may melt catheter materials, leaving foreign particles in the patient's blood stream.
  • determining the position and/or configuration of the electrodes is essential for catheters operated with bipolar PFA and where electrode distances between each other can change due to manipulation (especially if electrodes on different polarities come close).
  • the known method includes monitoring a system impedance with the return electrode positioned near the target location and the catheter electrode positioned within the body, detecting a positive deflection in the system impedance, the positive deflection indicative of arcing, and generating an alert, based on the detection, the alert indicating that arcing has occurred.
  • the known method does only derive some information about arcing for unipolar ablation though.
  • bipolar PFA which is the preferred method to produce a moat of electrical isolation in one shot the known method does not give any meaningful values and adding external impedances does not necessarily prohibit arcing.
  • the present disclosure is directed toward overcoming one or more of the above mentioned problems, though not necessarily limited to embodiments that do.
  • the techniques described herein relate to a system for detecting catheter movement during a measurement cycle, including: a measurement unit adapted to electrically connect to each of a plurality of electrodes positioned along a distal end of an ablation catheter, the measurement unit configured to periodically measure an impedance value at each of the plurality of electrodes during each of a plurality of measurement cycles; and an electronic control unit (ECU) configured to: receive from the measurement unit a plurality of measured impedance values for at least a portion of the plurality of electrodes for each of the plurality of measurement cycles, compare the measured impedance value for a first electrode for a first measurement cycle to the measured impedance value for the first electrode for one or more second measurement cycles to identify one or more measured impedance values from one or more of the second measurement cycles that is less than or greater than a predetermined value, and identify undesirable catheter movement based on said one or more measured impedance values from the one or more of the second measurement cycles that is less than or greater than the predetermined value for the first electrode.
  • ECU
  • the techniques described herein relate to a system for detecting catheter movement during a measurement cycle, including: an ablation catheter including a plurality of electrodes accommodated along a distal end of the ablation catheter; a measurement unit adapted to electrically connect to each of a plurality of electrodes positioned along a distal end of an ablation catheter, the measurement unit configured to periodically measure an impedance value at each active electroe in the plurality of electrodes; and an electronic control unit (ECU) configured to: receive from the measurement unit at least one measured impedance value for at least a portion of the plurality of electrodes for each of a plurality of measurement cycles, analyze the measured impedance values for a first electrode for a plurality of sequential measurement cycles and calculate a mean impedance value for the first electrode for the plurality of sequential measurement cycles, compare the measured impedance value for the first electrode for a first measurement cycle to the mean impedance value for the first electrode for the plurality of measurement cycles to determine if the measured impedance value for the first measurement cycle is
  • FIG. 1 depicts a distal end of a first embodiment of an ablation catheter in a perspective side view
  • FIG. 2 illustrates a delivery path for an ablation catheter leading to a pulmonary vein ostium of a human heart
  • FIGS. 3 and 3 A show part of the electric control of the electrode leads for the embodiment of the ablation catheter of FIG. 1 ;
  • FIG. 4 depicts the distal end of the ablation catheter of FIG. 1 with electrode numbering in a top view
  • FIGS. 5 and 6 show matrices containing AR indexes for each electrode pair and the impedance values of the ablation catheter of FIG. 1 for a saline position of the ablation portion;
  • FIG. 7 shows the ablation portion of the ablation catheter of FIG. 1 pressed to chicken heart tissue in a top view
  • FIGS. 8 and 9 show matrices containing AR indexes for each electrode pair and the CU value of the ablation catheter of FIG. 1 in the position shown in FIG. 7;
  • FIG. 10 shows another position of the ablation portion of the ablation catheter of FIG. 1 pressed to chicken heart tissue in a top view
  • FIGS. 11-12 show matrices containing AR indexes for each electrode pair and the CU value of the ablation catheter of FIG. 1 in the position shown in FIG. 10;
  • FIG. 13 depicts a schematic example of an applicable PFA waveform
  • FIG. 14 shows another position of the ablation portion of the ablation catheter of FIG. 1 pressed to a chicken heart tissue in a top view
  • FIG. 15 shows a matrix containing impedance values and an AR index (flagged) for the electrode pairs 1,2; 2,3; 2,9; 8,9; 9,10, respectively of the ablation catheter of FIG. 1 in the position shown in FIG. 14;
  • FIG. 16 shows another position of the ablation portion of the ablation catheter of FIG. 1 pressed to a chicken heart tissue in a top view
  • FIG. 17 shows a matrix containing impedance values and an AR index (flagged) for the electrode pairs 1,2; 2,3; 2,9; 8,9; 9,10, respectively of the ablation catheter of FIG. 1 in the position shown in FIG. 16;
  • FIG. 18 shows another position of the ablation portion of the ablation catheter of FIG. 1 pressed to a chicken heart tissue in a top view
  • FIG. 19 shows a matrix containing impedance values and an AR index (flagged) for the electrode pairs 1,2; 2,3; 2,9; 8,9; 9,10, respectively of the ablation catheter of FIG. 1 in the position shown in FIG. 18;
  • FIG. 20 shows another position of the ablation portion of the ablation catheter of FIG. 1 pressed to a chicken heart tissue in a top view
  • FIG. 20A shows another position of the ablation portion of the ablation catheter of FIG. 1 pressed to a chicken heart tissue in a top view;
  • FIG. 21 shows a matrix containing impedance values for the adjoining electrode pairs derived from a bipolar measurement and a CU value of the ablation catheter of FIG. 1 in the position shown in FIG. 20 calculated from these impedance values;
  • FIG. 21A shows a matrix containing impedance values for the adjoining electrode pairs derived from a bipolar measurement and a CU value of the ablation catheter of FIG. 1 in the position shown in FIG. 20A calculated from these impedance values;
  • FIG. 22 shows a table containing impedance values derived from a quasi-unipolar measurement at 500 kHz and a CU value calculated from these impedance values of the ablation catheter of FIG. 1 in the position shown in FIG. 20;
  • FIG. 22A shows a table containing impedance values derived from a quasi-unipolar measurement at 500 kHz and a CU value calculated from these impedance values of the ablation catheter of FIG. 1 in the position shown in FIG. 20A;
  • FIGS. 23-25 visualize three different pulse shapes for current measurements at each individual electrode
  • FIGS. 26-29 show four different positions of the ablation catheter of FIG. 1 , partly with respect to a chicken heart tissue in saline;
  • FIG. 30 shows a bar diagram containing impedance values determined for the four positions of FIGS. 26 to 29 with respect to each electrode of the ablation portion of the ablation catheter of FIG. 1 ;
  • FIG. 31 visualizes a flowchart for the use of a PFA catheter including PFA precheck determining AR indexes and CU value in order to treat paroxysmal atrial fibrillation;
  • FIGS. 32-33 show examples of visualization of impedance values for electrodes of an ablation section of an ablation catheter similar to the one of FIG. 1 ;
  • FIG. 34 is a flow diagram illustrating an example process for detecting catheter movement based on impedance values
  • FIG. 35 is a graph diagram illustrating example electrode graphs for detecting catheter movement based on impedance values
  • FIG. 36 is a graph diagram illustrating example electrode graphs for detecting catheter movement based on impedance values
  • FIG. 37 is a graph diagram illustrating example electrode graphs for detecting catheter movement based on impedance values
  • FIG. 38 is a graph diagram illustrating example electrode graphs for detecting catheter movement based on impedance values.
  • Disclosed herein are systems and methods for detecting catheter movement in a patient based on impedance values from an ablation catheter.
  • FIGS. 1 and 4 illustrate a distal portion of an ablation catheter 1 in accordance with a first embodiment.
  • the ablation catheter may be used for PFA, when used with the PFA generator and accessories, and is indicated for use in cardiac electrophysiological mapping (stimulation and recording) and in high-voltage, pulsed-field cardiac ablation.
  • Peak voltages are, for example, without limitation, +/-1 kV to 3 kV with a pulse width of up to 30 ps. Higher peak voltages (e.g. up to 10 kV) may be used provided the pulse duration is correspondingly shorter (e.g. 0.5 ps).
  • the catheter 1 has an elongated circular catheter shaft 10, which may connect with a handle comprising a steering mechanism at a proximal end (not illustrated). As a result, the catheter may control deflections of the depicted distal section carrying the ablation electrodes.
  • an ablation portion 12 is arranged, which comprises a plurality of loop sections 121, 122.
  • the concept of loop sections includes embodiments that use continuous loops or spirals configurations.
  • the catheter shaft may have an effective length of approximately 115 cm from the distal tip of the ablation portion 12.
  • Each of a first loop section 121 and a neighboring second loop section 122 exhibits ablation electrodes 120 (altogether, for example, 10, 12, 14, 16, or 32 electrodes), which are configured for delivering energy to tissue.
  • ablation electrodes 120 (altogether, for example, 10, 12, 14, 16, or 32 electrodes), which are configured for delivering energy to tissue.
  • two loops are illustrated in FIG. 1, more can be used. It is preferred that at least a partial third loop is used in order to provide sufficient overlap among resulting ablation zones.
  • the distal section comprises at least 45° of overlap of a 3 rd loop section with the previous two sections.
  • the ablation catheter 1 may be configured for delivering an electrical high voltage PFA signal to tissue via the ablation electrodes 120.
  • the ablation electrodes 120 may consist of or comprise gold and/or a platinum/iridium alloy.
  • electrodes 120 from different loop sections may be positioned so that electrodes of same polarity are aligned.
  • the ablation electrodes 120 of the second loop section 122 are arranged partly in a staggered manner with respect to the ablation electrodes 120 of the first loop section 121.
  • the electrodes are consecutively numbered as shown in FIG. 4 (see numbers at the electrodes).
  • the most distal electrode has the number 1, whereas the most proximal electrode is denoted with number 14. Different numbering is possible, as well.
  • the loop sections 121, 122 may further exhibit a plurality of mapping electrodes, which are configured for receiving electrical signals from tissue. Together, the loop sections 121, 122 form a three-dimensional spiral, which form a corkscrewsimilar form where the diameter of the loops decreases toward the distal end. Alternatively, they may form a plunger-like configuration where the diameter of the loops increases toward the distal end or any other suitable 3 -dimensional configuration (not shown).
  • the loop sections 121, 122 may comprise a shape memory material, for example, in the form of an inner structural support wire (not illustrated), for example a Nitinol wire as described above.
  • the loop sections 121, 122 may have super-elastic properties.
  • the ablation portion 12 may be constrained into an essentially elongate shape for the purpose of delivery to a target region in the human body by means of a (fixed or steerable) delivery sheath 15, which may also be referred to as an introducer sheath. At the target position, upon exiting a distal end of the delivery sheath 15, the ablation portion 12 may then recoil to its original (biased) shape.
  • each electrode 120 along the respective loop section 121, 122 is, for example, 4 mm. In general, the electrode length is in the range 1-10 mm, preferably 3-5 mm.
  • the catheter shaft 10 size may be compatible with an 8.5 F ID sheath and may consist of radiopaque extrudable polymer and, if applicable, a polymer-reinforcing braid. In general, the size of the catheter shaft 10 may be compatible with a 7 F to 14 F ID sheath.
  • the width between neighboring electrodes along the respective loop section may be chosen between 1 mm and 10 mm, preferably 3-6 mm, in order to provide a contiguous ablated area at the patient's tissue.
  • FIG. 2 schematically and exemplarily illustrates a delivery path for an ablation catheter 1 leading to a pulmonary vein ostium (PVO) of a human heart.
  • IVC inferior vena cava
  • RA right atrium
  • RV right ventricle
  • LA left atrium
  • LV left ventricle
  • PV pulmonary veins
  • the large black arrows indicate a delivery path passing through the IVC, the RA, transeptally through the septal wall (SW), and into the LA.
  • catheter 1 is steered to PVO regions.
  • the corkscrew type ablation catheter may be used for ablation in the area of the atrial end of the pulmonary vein close to PVO.
  • the form of the ablation portion 12 is configured such that it fits to the dimensions of the targeted PVO.
  • corkscrew-type catheters may be used to ablate at the SVC or at Appendages, such as the left or right atrial appendages (LAA or RAA).
  • Reliable full ablation along a whole circumference is achieved with the first embodiment of the ablation catheter shown in FIGS. 1 and 4 at their respective position within the heart or the vein to which the form is adapted.
  • a small compression of the ablation portion 12 of the respective catheter 1 may be possible during ablation into the direction of the longitudinal axis of the spiral.
  • the ablation procedure using one of the ablation catheters 1 may start after the ablation portion 12 is in the correct position relative to the targeted tissue, for example at a PVO.
  • the assessment of the position and/or configuration of the ablation electrodes 120 is provided prior and/or between two ablation steps (if applicable) and is explained in more detail below.
  • the ablation electrodes 120 will provide pulsed electric field in a unipolar or bipolar arrangement. Peak voltages are, for example, without limitation, +/-1 kV to 3 kV with a pulse width of up to 30 ps. Higher peak voltages (e.g. up to 10 kV) may be used provided the pulse duration is correspondingly shorter (e.g. 0.5 ps).
  • the pulse width may be 5 ps (between 0.5-30 ps) forming a pulse train comprising up to 500 pulses/train.
  • FIG. 3A also shows connectivity that can be used to generate unipolar or bipolar electric fields. ECUs in FIGS. 3 and 3A may control application of PFA fields.
  • FIG. 3 A illustrates a catheter 1401 (such was the one with reference number 1 from FIGS. 1 and 4) with its electrodes driven by ECU 1403. ECU 1403 can be controlled to deliver field vectors 1402 that cover the tissue zone in between catheter 1401 spiral arms/loops. By doing so, the AR index may be determined.
  • the PFA generator may be connected to one of the electrodes as the reference electrode instead of to the grounding pad 1404.
  • neighboring (adjoining) electrodes 120 may be paired along the loop sections 121, 122, across two neighboring loop sections 121 and 122 or any other pre-defined pair combination, in particular for impedance determination for AR value and/or CU value. Further, the electrodes 120 may be used in a unipolar arrangement. In this case, a ground pad 1404 may be provided at the surface of the patient's body. Alternatively, one of the non-adjacent electrodes 120 may be used as reference electrode thereby forming a quasi-unipolar arrangement.
  • the ablation catheter 1 may comprise a switch unit 60 connected to and controlled by the ECU 70.
  • the switch unit 60 provides the respective phase of the pulsed electric field provided by the waveform generator 50 to the predefined electrode lead 61 and thereby to the predefined electrode 120 wherein each electrode lead 61 is electrically connected to one particular electrode 120 at the ablation portion 12.
  • the switch unit 60 comprises a switch matrix and may realize any configuration of phase distribution, for example, such that two neighboring electrodes along the loop sections, across the loop sections and any other electrodes are paired.
  • the switching signal and configuration information is provided by the ECU 70.
  • ECU 70 further may provide data processing of electrical or biopotential data or impedance data acquired the electrodes of ablation catheter 1.
  • mapping electrodes located in the ablation portions 12 may comprise mapping electrodes for determining the electrical potential of the surrounding tissue in order to observe the ablation progress at pre-defined time points during ablation procedure.
  • the ablation electrodes 120 may be switched into the mapping mode and back into the ablation mode.
  • the AR value and CU value are determined in order to assess the positions of the electrodes 120 and/or their configuration with regard to each other and/or with regard to the tissue under treatment.
  • the ablation catheter of FIGS. 1 and 4 is measured with regard to the impedance of all pairs of the 14 electrodes in saline (for comparison), a first position axially pressed to a chicken heart tissue (see FIG. 7) and in a second position axially pressed to a chicken heart tissue wherein black rubber bands keep the electrodes 4 and 12 close to each other (see FIG. 10).
  • the matrices of FIGS. 5 and 6 belong to the saline configuration, the matrices of FIGS. 8 and 9 to the position shown in FIG. 7 and the matrices of FIGS. 11 and 12 to the position shown in FIG. 10.
  • AC voltage signals with a frequency of 500 kHz with a peak voltage (amplitude) of 1 V are chosen.
  • the matrices of FIGS. 5, 8 and 11 show the AR index calculated from the bipolar impedance measurement values Z x>y of the electrode pair x,y.
  • the number of the electrodes of the particular electrode pair can be found in the respective header line and the first row.
  • the value at the row-line-intersection contains the AR index of the respective electrode pair x,y determined from the impedance measurement values for 500 kHz.
  • the AR index is calculated using the formula:
  • the matrix of FIG. 11 contains the AR index values calculated in a similar way for the configuration of FIG. 10 and a frequency of 500 kHz . It is apparent that in particular the electrode pairs 3, 11 and 4, 12 show considerably higher AR index values than any other AR index value of this matrix. For these pairs a risk for arcing exists, if the electrodes of these pairs would be at different polarities.
  • the calculated AR indexes of the respective electrode pairs are provided for all electrode pairs but the adjoining electrode pairs (marked in the diagonal) for the respective ablation portion position.
  • the impedances of the adjoining electrode pairs are provided.
  • the AR index of the electrode pair 5 and 14 is highlighted since it indicates a high arcing risk (AR index >0.25).
  • the electrode pair 2, 9 has a higher arcing risk.
  • the AR index values for the electrode pairs 4, 12 and 5, 13 are neglected since these electrodes share the same polarity and therefore no risk for arcing exists.
  • FIGS. 6, 9 and 12 contain the CU value for the respective position in the upper left comer calculated from the following formula (see explanation above) and the measured bipolar impedances of the adjoining electrodes: It appears from the matrices in FIGS. 6. 9 and 12 that the contact uniformity of the position shown in FIG. 7 is better than of the position shown in FIG. 10 as the CU value is greater (0.92>0.86). The contact uniformity is best in the saline position (0.99) — if all electrodes without contact, i.e. all electrodes are floating in saline.
  • FIG. 14 shows a position of the ablation portion of the ablation catheter of FIGS. 1 and 4 in which the electrodes 2, 9 are in close proximity (see encircled area). Accordingly, the AR index of these electrodes is 0.455 indicating the high arcing risk (see matrix shown in FIG. 15).
  • the arcing threshold for the pulse parameters P, Ii, I2 and PN given above was determined as 0.9 kV confirming the calculated AR index.
  • FIG. 16 shows a position of the ablation portion of the ablation catheter of FIGS. 1 and 4 where electrodes 2, 9 do not overlap (see marked area, so-called edge-edge position). Accordingly, the AR index shown in FIG. 17 is lower than the one of FIG. 15.
  • the lowest AR index may be found for the position of these electrodes 2, 9 shown in FIG. 18 in which these electrodes are sufficiently far away thereby having a low arcing risk (see marked area). Accordingly, the AR index of this electrode pair 2, 9 is close to zero (see FIG. 19).
  • the quasi-unipolar impedance one electrode e.g. electrode 1 is measured against all electrodes of opposing polarity (e.g.
  • FIG. 20 shows a position in which three electrodes (2, 9, 10) are floating in saline while the others are in contact with the heart tissue.
  • the CU value (bipolar, see FIG. 21) is 0.89 and the CU value (quasi-unipolar) is determined as 0.86 (see FIG. 22) which is comparably low thereby indicating bad contact uniformity.
  • the position shown in FIG. 20A has all electrodes in contact with the chicken heart's tissue. Accordingly, CU value (bipolar, see FIG. 21 A) is 0.92 and the CU value (quasi-unipolar) is determined as 0.91 (see FIG. 22A).
  • FIGS. 23 and 24 show the current measurements using a single pulse for each of the electrodes in order to determine CU, namely a rectangular pulse.
  • FIG. 23 represents a rectangular current waveform as response to the rectangular voltage pulse.
  • the tooth shaped waveform shown in FIG. 24 represents the measured current in the case of a short circuit. Even in this case a current measurement and thereby impedance measurement is possible.
  • Current measurements (total current as well as current flow through each electrode) have been performed with a current transformer (Magnelab CT-CO.5) while a 500 V rectangular biphasic pulse (4 ps pulse length, 25 ps interphase delay) was applied.
  • the impedances determined from the peak current measurement values are displayed as bars for each electrode (electrode number at x-axis) and impedance (in Q at y-axis).
  • the first bars refer to the position shown in FIG. 26 (ablation portion in saline)
  • the second bars refer to the position shown in FIG. 27
  • the third bars refer to the position shown in FIG. 28, and the fourth bars refer to the position shown in FIG. 29.
  • the impedance values shown for the saline configuration are low because of the higher conductivity of saline ( ⁇ 0.7 S/m, which is matched to human blood in this experiment) compared to the chicken heart tissue.
  • the electrodes 2 to 5 and 11 to 13 have lesser contact, whereas the other electrodes have better contact.
  • the electrodes 6 and 15 are short circuited and the position of the ablation portion needs to be corrected (impedance close to zero).
  • the position shown in FIG. 29 provides impedance values similar to the position of FIG. 27.
  • the catheter 1 is manipulated to targeted PV antrum in the usual way.
  • the ablation portion 12 is covered by the delivery sheath 15 until the distal end of the catheter reaches the targeted region.
  • the catheter provides quality EGMs to confirm placement near PV and to assess pre-PFA amplitudes and/or an electro-anatomical mapping system displays the 3 -dimensional shape and location of the catheter 1.
  • the AR index and/or CU value measurement is started by, e.g., short pressing a foot pedal of the generator 50 or by pressing a button on the generator 50.
  • step 204 accurate current or impedance measurements between electrodes 120 of the catheter are provided as explained above in detail by the measurement unit 68, the waveform generator 50 and the ECU 70.
  • the measurement may be provided to all electrodes 120 of the ablation portion 12 or, alternatively, electrodes at positions at risk are measured.
  • the current or impedance measurement values are processed by the ECU 70 and the impedance values for all ablation electrodes, AR indexes of electrode pairs and/or the CU value for all ablation electrodes of the ablation portion 12 are determined in the following step 205.
  • the GUI connected with the ECU 70 colors catheter electrodes or a respective bar diagram at risk of arcing in easy-to-see colors as shown in FIGS. 32 and 33.
  • FIG. 32 depicts the ablation portion 12 with 16 numbered electrodes 120 and a respective bar diagram 230, wherein the height of a bar shown with reference to the electrode number represents the impedance value.
  • the bar diagram shows a low impedance for electrodes number 7 and 10.
  • Electrodes 3 and 4 are configured as mapping electrodes and therefore do not measure impedance during pulse delivery.
  • FIG. 32 may also display the measured impedance values directly at the electrode location of electrodes 7 and 10 at the ablation portion 12 with different colors, wherein each color represents the deviation from the target impedance value.
  • the illustration of electrode number 10 visualizes a greater deviation from the target impedance value than the illustration of electrode number 7.
  • the electrodes are grouped such that the critical electrodes are split into separate energy-delivery groups (step 208).
  • the GUI displays impedances, AR indexes and/or CU value of electrodes that are in an acceptable range. If there is no risk of arcing identified step 209 can be directly reached from step 206.
  • a PFA treatment is initiated by, e.g., a foot pedal of the ablation generator is continued to be pressed (e.g., for some number of seconds) by the HCP to the patient if an acceptable positioning of the ablation catheter is shown.
  • step 211 the procedure continues with step 204 if there was no PFA precheck measurement, with step 212 if the PFA precheck measurement is OK, and with step 213 if the PFA precheck measurement failed.
  • Step 213 contains a repositioning of the catheter, in particular of its ablation portion 12 with respect to the targeted PV antrum. After step 213 the procedure continues with step 202 (see above).
  • step 212 the procedure continues with step 213 (see explanation of step 213 above). If the PFA delivery is not aborted during treatment, the procedure continues with step 214 the PFA generator provides accurate delivery of ablation energy according to pulse protocol to the user by the electrodes 120 of the ablation portion 12. According to above procedure, the PFA arcing risk and/or contact uniformity is checked prior PFA ablation in order to guarantee the catheter position with the highest contact uniformity and lowest arcing risk for all electrodes taking part in the PFA. Accordingly, dangerous arcing can be avoided and the electrodes have a uniform contact to the targeted tissue in order to provide high-quality PFA realizing a moat of electrical isolation in one shot.
  • FIG. 34 a method for detecting catheter movement inside a patient based on impedance values during pulsed field ablation is provided.
  • the illustrated method may be performed by any of the systems previously described.
  • a drawback of current ablation catheter systems is that patient movement during PFA may lead to ineffective or incomplete ablations, or even treatments at the wrong sites which might pose a danger to patients. Movement of the catheter may include gradual, slow movement overtime, or rapid movement.
  • PFA an additional possibility that may cause catheter movement stems from stimulation of the phrenic nerve during PFA, which leads to movement of the thorax or coughing, either of which may cause catheter movement.
  • the non-therapeutic pulses can be used in the embodiments described above to determine AR or CU before applying pulses with a therapeutic effect.
  • the ECU may measure an impedance value only at those electrodes that are activated and ablating tissue (i.e., delivering therapeutic pulses).
  • the ECU may also measure an impedance value at all electrodes when some or all electrodes are activated and ablating tissue.
  • the ECU may measure and store the impedance values a plurality of times during each cardiac cycle of the subject.
  • the ECU determines if the treatment protocol has finished and the treatment has not finished, then the ECU proceeds to apply the next PFA pulse train at 3616 and loops back to measure the impedance values at 3610.
  • undesirable catheter movement is identified when a difference between measured impedance values at a particular electrode exceeds a threshold value across adjacent cardiac cycles.
  • undesirable catheter movement may be determined by formula 1 :
  • One or more impedances values of electrode i during cardiac cycle j is greater or smaller than 10 % compared to cardiac cycle j-2 for j > 7 (or 10) based on the rolling median of each value (window of 5 values centered around cardiac cycle j):
  • FIG. 38 is a graph diagram illustrating an example electrode graphs for detecting catheter movement based on impedance values.
  • the graph on the left corresponds to one of the electrodes (Z 10) on the ablation catheter and shows the impedance value (y axis) measured at the particular electrode (Z 10) during each of a plurality of cardiac cycles (x axis).
  • time windows 4002 and 4004 that indicate a meaningful change in measured impedance values.
  • the changes in impedance values in time windows 4002 and 4004 correspond to breathing of the subject and do not indicate catheter movement.
  • the graph on the right corresponds to the analysis of the measured impedance values for the particular electrode (Z10) and illustrates a difference between an average of the measured impedance values for a first cardiac cycle and an average of the measured impedance values for a second cardiac cycle.
  • the range of cardiac cycles that are analyzed to determine a difference value for a target cardiac cycle may be increased or decreased.
  • the difference in the average impedance values between the target cardiac cycle and another cardiac cycle within +/- two cardiac cycles may be analyzed.
  • the difference in the average impedance values between the target cardiac cycle and another cardiac cycle within +/- five cardiac cycles may be analyzed.

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Abstract

L'invention concerne un système de traitement de tissu de patient par administration d'impulsions haute tension comprenant un cathéter d'ablation, une unité de mesure et une unité de commande électronique (ECU). L'unité de mesure est conçue pour effectuer des mesures à l'aide d'une source d'énergie, les valeurs de mesure d'impédance et/ou de courant étant déterminées en réponse à une tension alternative et/ou à au moins une impulsion de tension. L'ECU est conçue pour recevoir et analyser lesdites valeurs de mesure d'impédance fournies par l'unité de mesure et déterminer un mouvement de cathéter non souhaitable sur la base desdites valeurs de mesure d'impédance.
PCT/US2025/018807 2024-03-15 2025-03-06 Détection de mouvement de cathéter d'ablation sur la base de valeurs d'impédance Pending WO2025193517A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018102376A1 (fr) 2016-11-29 2018-06-07 St. Jude Medical, Cardiology Division, Inc. Systèmes d'électroporation et cathéters pour systèmes d'électroporation
US20210007796A1 (en) * 2019-07-10 2021-01-14 Zidan Medical, Inc. Systems, devices and methods for treating lung tumors
US20230256252A1 (en) * 2020-06-16 2023-08-17 CARDIONOMIC, Inc. Chronically implantable systems and methods for affecting cardiac contractility and/or relaxation
US20230404676A1 (en) * 2022-05-20 2023-12-21 Biosense Webster (Israel) Ltd. Visualizing a quality index indicative of ablation stability at ablation site

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018102376A1 (fr) 2016-11-29 2018-06-07 St. Jude Medical, Cardiology Division, Inc. Systèmes d'électroporation et cathéters pour systèmes d'électroporation
US20210007796A1 (en) * 2019-07-10 2021-01-14 Zidan Medical, Inc. Systems, devices and methods for treating lung tumors
US20230256252A1 (en) * 2020-06-16 2023-08-17 CARDIONOMIC, Inc. Chronically implantable systems and methods for affecting cardiac contractility and/or relaxation
US20230404676A1 (en) * 2022-05-20 2023-12-21 Biosense Webster (Israel) Ltd. Visualizing a quality index indicative of ablation stability at ablation site

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