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WO2025193520A1 - Détection de collision d'électrodes basée sur des valeurs d'impédance - Google Patents

Détection de collision d'électrodes basée sur des valeurs d'impédance

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Publication number
WO2025193520A1
WO2025193520A1 PCT/US2025/018816 US2025018816W WO2025193520A1 WO 2025193520 A1 WO2025193520 A1 WO 2025193520A1 US 2025018816 W US2025018816 W US 2025018816W WO 2025193520 A1 WO2025193520 A1 WO 2025193520A1
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WO
WIPO (PCT)
Prior art keywords
electrode
electrodes
ablation
impedance values
impedance
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/US2025/018816
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English (en)
Inventor
Dr. Steffen HOLZINGER
Dr. Laura BOEHMERT
Dr. Dorin PANESCU
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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 WO2025193520A1 publication Critical patent/WO2025193520A1/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
    • A61B18/1206—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
    • 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
    • A61B18/1233—Generators therefor with circuits for assuring patient safety
    • 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
    • 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
    • A61B2018/00315—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body for treatment of particular body parts
    • A61B2018/00345—Vascular system
    • A61B2018/00351—Heart
    • A61B2018/00357—Endocardium
    • 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
    • A61B2018/00571—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body for achieving a particular surgical effect
    • A61B2018/00613—Irreversible electroporation
    • 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
    • A61B2018/00642—Sensing and controlling the application of energy with feedback, i.e. closed loop control
    • 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
    • A61B2018/00696—Controlled or regulated parameters
    • A61B2018/00702—Power or energy
    • A61B2018/00708—Power or energy switching the power on or off
    • 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
    • A61B2018/00636—Sensing and controlling the application of energy
    • A61B2018/00898—Alarms or notifications created in response to an abnormal condition
    • 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 electrode collision during pulsed-field ablation, 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, wherein a first electrode and a second electrode are configured to deliver energy at the first polarity, identify one or more impedance values for the first electrode corresponding to one or more measurement cycles that are greater than an average impedance value for the first electrode for the plurality of measurement cycles, identify one or more impedance values for the second electrode corresponding to one or more measurement cycles that are less than an average impedance value for the second electrode for the plurality of measurement cycles, analyze the one
  • the techniques described herein relate to a method for detecting electrode collision during pulsed-field ablation, including: periodically measuring an impedance value at each of a plurality of electrodes positioned along a distal end of a catheter shaft during each of a plurality of measurement cycles, wherein each electrode is configured to deliver energy at a first polarity or a second polarity; identifying one or more impedance values for a first electrode corresponding to one or more measurement cycles that are greater than an average impedance value for the first electrode for the plurality of measurement cycles, identifying one or more impedance values for a second electrode corresponding to one or more measurement cycles that are less than an average impedance value for the second electrode for the plurality of measurement cycles, wherein the first electrode and the second electrode are configured to deliver energy at a first polarity, analyzing the one or more identified impedance values for the first electrode and the one or more identified impedance values for the second electrode to determine a first identified impedance value for the first electrode corresponding to a first measurement cycle
  • 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. 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. 36 is a flow diagram illustrating an example process for detecting collisions between electrodes of the same polarity during PFA
  • 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.
  • 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.
  • 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.
  • the ablation catheter further comprises a measurement unit 68 which is connected to the ECU 70 and a switch unit 60 with the waveform generator 50.
  • the measurement unit 68 is configured to measure peak current and peak voltage as well as impedance at the respective electrode lead 61 and transmit these data to the ECU for further analysis. Further, the measurement unit 68 provides the electrodes 120 at the respective lead(s) 61 with pre-defined measurement signals (current or voltage pulses) via the waveform generator 50 in order to measure the above-mentioned parameter.
  • 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:
  • 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, ft, I 2 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. against all even electrodes, and electrode 2 against all odd electrodes).
  • 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) in FIG. 30.
  • 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, e.g., by short pressing a foot pedal of the generator 50 or pressing a button of 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 illustrated electrode number 10 visualizes a greater deviation from the target impedance value than the illustrated 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.
  • 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 is agraph diagram illustrating example impedance graphs 3610 and 3615 fortwo electrodes of the same polarity making intermittent contact.
  • the top graph shows measured impedance values (Y axis) for electrode Z7 over a plurality of cardiac cycles (X axis).
  • the bottom graph shows measured impedance values (Y axis) for electrode Z15 over the same plurality of cardiac cycles (X axis).
  • electrode Z7 and electrode Z15 are configured to provide electrical energy during PFA at the same polarity.
  • Cardiac cycles may also be referred to herein as measurement cycles and in one aspect, a measurement cycle may be a portion of a cardiac cycle or a combination of more than one cardiac cycle or a combination of one cardiac cycle with a portion of another cardiac cycle.
  • a group 3620 of measured impedance values stands apart from the other measured impedance values for electrode Z7. These measured impedance values are higher than the other measured impedance values for electrode Z7 and higher than an average impedance value for electrode Z7 during the plurality of cardiac cycles shown on the graph.
  • a group 3625 of measured impedance values stands apart from the other measured impedance values for electrode Z15. These measured impedance values are lower than the other measured impedance values for electrode Z15 and higher than an average impedance value for electrode Z15 during the plurality of cardiac cycles shown on the graph.
  • electrodes Z7 and Z15 form an electrode pair having the same polarity and a number of measured impedance values that deviate from the average impedance values for the particular electrode during the same cardiac cycles.
  • This correspondence between deviant/outlier measured impedance values during the same cardiac cycles for two electrodes having the same polarity demonstrates an intermittent electrode collision.
  • the measured impedance value 3630 for electrode Z7 appears to be higher than the average impedance value for electrode Z7 during the illustrated cardiac cycles, however, the measured impedance value 3630 does not have a corresponding measured impedance value for electrode Z15 that is lower than the average impedance value for electrode Z15 and therefore no electrode collision is demonstrated.
  • the nature of the correspondence between the measured impedance values in the illustrated embodiment is such that the one-to-one cardiac cycle correspondence, as opposed to a contiguous series of cardiac cycle correspondence, suggests that electrodes Z7 and Z 15 are colliding due to the periodic beating of the heart and/or the periodic breathing of the patient.
  • a deviant measured impedance value may be due to an electrode colliding directly with another electrode, an electrode colliding partially with another electrode and partially with the tubing/lumen, or an electrode colliding with the tubing/lumen.
  • FIG. 35 is agraph diagram illustrating example impedance graphs 3710 and 3715 fortwo electrodes of the same polarity making durable contact.
  • the top graph shows measured impedance values (Y axis) for a first electrode over a plurality of cardiac cycles (X axis).
  • the bottom graph shows measured impedance values (Y axis) for a second electrode over the same plurality of cardiac cycles (X axis).
  • the first electrode and the second electrode are configured to provide electrical energy during PFA at the same polarity.
  • two groups 3720 and 3730 of measured impedance values stand apart from the other measured impedance values for the first electrode. These measured impedance values are higher than the other measured impedance values for the first electrode and higher than an average impedance value for the first electrode during the plurality of cardiac cycles shown on the graph.
  • two groups 3725 and 3735 of measured impedance values stands apart from the other measured impedance values for the second electrode. These measured impedance values are lower than the other measured impedance values for the second electrode and higher than an average impedance value for the second electrode during the plurality of cardiac cycles shown on the graph.
  • the measured higher impedance values for the first electrode corresponds directly to the measured lower impedance values for the second electrode in the same first contiguous series of cardiac cycles 3740.
  • the measured higher impedance values for the first electrode in a second contiguous series of cardiac cycles 3745 correspond directly to the measured lower impedance values for the second electrode in the same second contiguous series of cardiac cycles 3745.
  • the first electrode and the second electrode form an electrode pair having the same polarity and a number of measured impedance values that deviate from the average impedance values for the particular electrode during the same contiguous series of cardiac cycles.
  • This correspondence between deviant/outlier measured impedance values during the same contiguous series of cardiac cycles for two electrodes having the same polarity demonstrates a durable electrode collision.
  • FIG. 36 is a flow diagram illustrating an example process 380 for detecting collisions between electrodes of the same polarity during PFA.
  • the process of FIG. 36 may be carried out by one or more of the previously described systems.
  • 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.
  • detecting collisions between electrodes of the same polarity during PFA may be determined when the following two equations are both true for the same cardiac cycle: median ⁇ fZi j — median 5 (Z i j_ 2 ) median ⁇ fZij — median 5 (Z i j_ 2 )
  • FIG. 36 illustrates an example process that may be employed with a catheter system and enables detection of both gradual and rapid movements of the catheter.
  • the system comprises a catheter with a plurality of electrodes (e.g., 10, 12, 14, 16, or 32) that are electrically connected to an electronic control unit (ECU) that functions at least in part as a PFA generator.
  • the catheter has at least 10 electrodes.
  • the ECU is configured to periodically measure an impedance value at a plurality of electrodes on the catheter.
  • the ECU measures an impedance value at each active electrode on the catheter a plurality of times during each cardiac cycle.
  • An active electrode is an electrode on the catheter that delivers therapeutic energy to tissue.
  • the impedance value data for each electrode that was measured is analyzed by the ECU and the ECU is configured to provide an alert when a collision between electrodes of the same polarity is detected by the analysis.
  • the alert may be an audible signal or an update on a graphical user interface (or both), so that the physician may take an appropriate action (e.g., pause PFA delivery and reposition the catheter).
  • the ablation catheter with the plurality of electrodes is positioned at the target tissue.
  • the PFA settings are selected for the PFA particular treatment.
  • the PFA treatment commences.
  • a number (n) of non-therapeutic pulses are delivered (where, e.g., n may be 1 to 5), and at 3830, the ECU measures an impedance value at each of the electrodes on the catheter or at selected electrodes on the catheter.
  • 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 or just one time during each cardiac cycle.
  • the ECU determines if there has been a collision between electrodes having the same polarity. In one aspect, to make this determination, the ECU calculates an average impedance value for each electrode across a plurality of cardiac cycles. Next, the ECU compares the measured impedance value for each electrode during each of the cardiac cycles to the average impedance value for the respective electrode to determine if any measured impedance values deviate from the calculated average impedance value for the respective electrode. If the difference between the measured impedance value and the average impedance value exceeds a predetermined threshold amount, the ECU identifies the measured impedance value and corresponding cardiac cycle as an outlier. If the ECU identifies two electrodes having the same polarity that each have an outlier measured impedance value during the same cardiac cycle, then the ECU determines that an electrode collision happened during that cardiac cycle.
  • 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 3855 and loops back to measure the impedance values at 3830.
  • FIG. 38 is a flow diagram illustrating an example process 400 for monitoring impedance values during pulsed field ablation to detect collisions between electrodes of the same polarity.
  • the process of FIG. 38 may be carried out by one or more of the previously described systems.
  • the ECU collects and evaluates impedance values as previously described with respect to FIGS. 38 and 39.
  • the identified decrease in the average impedance value is analyzed to determine if the decrease exceeds a first predetermined threshold. If the decrease does not exceed the first predetermined threshold, the system returns to monitoring the impedance values at 4010.
  • the system may be configured to terminate PFA delivery.
  • the low impedance threshold may be 80 Ohms. This low impedance threshold can be used to identify same polarity collisions which pose a threat for arcing: if the distance between electrodes of different polarity becomes low or if they collide, the impedance value will be less than the low impedance threshold.
  • the high impedance threshold may be 350 Ohms. This high impedance threshold can be used to identify collisions when the catheter is compressed and electrodes touch the plastic tubing of the catheter. Such a collision with the tubing/lumen may lead to a high impedance above the high impedance threshold.

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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 la présence d'une collision d'électrodes ayant la même polarité sur la base desdites valeurs de mesure d'impédance.
PCT/US2025/018816 2024-03-15 2025-03-06 Détection de collision d'électrodes basée sur des valeurs d'impédance Pending WO2025193520A1 (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
US20220233235A1 (en) * 2021-01-22 2022-07-28 CRC EP, Inc. Ablation Catheter for Pulsed-Field Ablation and Method for Electrode Position Assessment for Such Catheter
US20220233234A1 (en) * 2021-01-22 2022-07-28 CRC EP, Inc. Ablation Catheter and Operation Method of Same
US20230309832A1 (en) * 2020-05-29 2023-10-05 Medtronic, Inc. Presentation of patient information for cardiac shunting procedures

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
US20230309832A1 (en) * 2020-05-29 2023-10-05 Medtronic, Inc. Presentation of patient information for cardiac shunting procedures
US20220233235A1 (en) * 2021-01-22 2022-07-28 CRC EP, Inc. Ablation Catheter for Pulsed-Field Ablation and Method for Electrode Position Assessment for Such Catheter
US20220233234A1 (en) * 2021-01-22 2022-07-28 CRC EP, Inc. Ablation Catheter and Operation Method of Same

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