Sequential activation of electrode pairs during irreversible electroporation (IRE)

Abstract

To provide an irreversible electroporation (IRE) method.SOLUTION: An irreversible electroporation (IRE) method includes placing multiple electrodes of a catheter in contact with tissue of an organ. Bipolar IRE pulses are generated. The tissue is ablated by applying the bipolar IRE pulses to pairs of the electrodes, in accordance with order in which successive activations of a given electrode pair are interleaved with activations of at least one other electrode pair, and are spaced in time by at least a predefined duration.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates generally to invasive ablation using electrical signals, and more particularly to irreversible electroporation (IRE) of cardiac tissue. [Background technology]

[0002] Techniques using medical probes to perform irreversible electroporation (IRE) of body tissue have previously been proposed in the patent literature. For example, U.S. Patent Application Publication No. 2020 / 0009378 describes methods, systems, and devices for electroporation. The system may include a medical device having multiple electrodes mounted on an expandable element and an energy generator in communication with the electrodes. The energy generator may have processing circuitry configured to selectively deliver electroporation energy to at least one of the electrodes. The processing circuitry may determine whether an alert condition exists and, if so, may stop delivery of electroporation energy to one or more electrodes identified as causing the alert condition and / or prevent delivery of electroporation energy to one or more electrodes identified as causing the warning condition. The energy generator may also be configured to deliver electroporation energy in a sequence of multiple energy delivery patterns to improve lesion formation. In one embodiment, a bipolar signal is applied using all pairs of multiple electrodes simultaneously to prevent overheating of certain electrodes, which may be disconnected from the energy generator.

[0003] As another example, U.S. Patent Application Publication No. 2018 / 0214202 describes methods, systems, and devices for increasing the efficiency and effectiveness of energy delivery and tissue mapping. One system includes a processing element having multiple electrodes and an energy generator configured to deliver electrical energy pulses to the electrodes in various patterns. For example, the electrodes may be arranged in closely spaced pairs. The energy generator may deliver mapping energy to each electrode of each pair individually to map tissue, or may deliver ablation energy to each pair of electrodes together so that each pair is treated like a single electrode and ablation energy, such as bipolar ablation energy, can be delivered between adjacent pairs. One system includes at least one concave electrode, a configuration that concentrates energy and drives it deeper into tissue. One system includes neutral electrodes between active electrodes, and the energy generator selectively couples the neutral electrodes to modify the ablation pattern. In one embodiment, the effective electrode surface is increased by connecting several electrodes together to prevent overheating of the electrodes. In another embodiment, the heated electrode is cut to reduce the heat.

[0004] U.S. Patent Application Publication No. 2016 / 0113709, for example, describes selective cell ablation by electroporation, applicable to bulk tissue within a beating heart. Protocol parameters potentially induce tissue loss without thermal damage. The device and method may be applicable to myocardial tissue ablation to treat arrhythmias, obstructive hypertrophy, and / or to generate natural scaffolds for myocardial tissue engineering. In some embodiments of the present invention, pulses are delivered alternately to different pairs of electrodes. In some embodiments, the intensity (pulse voltage, frequency, number, and / or duration) of the electroporation protocol is limited by the requirement to avoid localized heating and cause thermal damage. Thus, for example, electroporation potentials are delivered alternately between electrode pairs (optionally using potential differences corresponding to differences in interelectrode distance to maintain the strength of the electroporation field). In such a configuration, each electrode may be involved in only half of the activated pairs (e.g., used half the time). Summary of the Invention [Means for solving the problem]

[0005] One embodiment of the present invention, described below, provides an irreversible electroporation (IRE) method that includes placing multiple electrodes of a catheter in contact with tissue of an organ. Bipolar IRE pulses are generated. The tissue is ablated by applying the bipolar IRE pulses to pairs of electrodes according to a sequence in which successive activations of a given electrode pair are interleaved with activations of at least one other electrode pair and are separated in time by at least a predetermined duration.

[0006] In some embodiments, applying a bipolar IRE pulse includes applying a bipolar IRE pulse between adjacent electrodes.

[0007] In some embodiments, applying the bipolar IRE pulse includes applying at least a portion of the bipolar IRE pulse between non-adjacent electrodes.

[0008] In one embodiment, applying the bipolar IRE pulse includes applying at least a portion of the bipolar IRE pulse between a pair of electrodes.

[0009] In another embodiment, the electrode pairs have the same inter-electrode distance.

[0010] In some embodiments, the tissue includes cardiac tissue, and applying the bipolar IRE pulse includes gating the bipolar IRE pulse to synchronize with a refractory period of the cardiac tissue.

[0011] According to another embodiment of the present invention, there is further provided an irreversible electroporation (IRE) system including a catheter, an IRE ablation power supply, and a processor. The catheter has a plurality of electrodes configured to be placed in contact with tissue of an organ. The IRE ablation power supply is configured to generate bipolar IRE pulses. The processor is configured to ablate tissue by applying the bipolar IRE pulses to pairs of electrodes according to a sequence in which successive activations of a given electrode pair are interleaved with activations of at least one other electrode pair and are separated in time by at least a predetermined duration.

[0012] In some embodiments, the system further includes a switch assembly configured to switch the IRE ablation power source between the electrode pairs, and the processor is configured to apply the bipolar IRE pulses in a sequence by controlling the switch assembly. [Brief explanation of the drawings]

[0013] The present invention will be more fully understood from the following detailed description taken in conjunction with the drawings, in which: [Figure 1] 1 is a schematic, pictorial illustration of a catheter-based position tracking and irreversible electroporation (IRE) ablation system, in accordance with an exemplary embodiment of the present invention; [Figure 2]2 is a schematic side depiction of a multi-electrode deflectable tip section of the catheter of FIG. 1, in accordance with an exemplary embodiment of the present invention. [Figure 3] 1 is a schematic front view of sequenced energization of electrode pairs of a multi-electrode deflectable tip section of a catheter deployed in the form of a loop, in accordance with an exemplary embodiment of the present invention; FIG. [Figure 4] 3 is a flow chart that schematically illustrates a method of using the electrode pairs of the catheter head of FIG. 2 for sequential irreversible electroporation (IRE) ablation, in accordance with an exemplary embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] Overview Irreversible electroporation (IRE), also known as pulsed field ablation (PFA), may be used as an invasive treatment modality to kill tissue cells by exposing them to high-voltage pulses. Specifically, IRE pulses have potential use in killing myocardial tissue cells to treat cardiac arrhythmias. Cell destruction occurs when the transmembrane potential exceeds a threshold, resulting in cell death and thus the development of tissue lesions. Therefore, a particular benefit is the use of high-voltage bipolar electrical pulses (e.g., using a pair of electrodes in contact with the tissue) to generate a high electric field (e.g., above a certain threshold) to kill tissue cells between the electrodes.

[0015] In the context of this disclosure, a "bipolar" voltage pulse means a voltage pulse applied between two electrodes of a catheter (as opposed to a monopolar pulse, which is applied by the catheter electrodes relative to some common ground electrode not located on the catheter, for example).

[0016] To perform IRE ablation over a relatively large tissue area of ​​an organ, such as the circumference of the ostium of a pulmonary vein (PV), it is necessary to use multiple pairs of electrodes on a multi-electrode catheter. To make the generated electric field as spatially uniform as possible over a large tissue area, it is best to have selected pairs of electrodes with overlapping magnetic fields, or at least adjacent magnetic fields. However, there is a Joule heating component that occurs in the IRE-generated magnetic field, and this heating can damage the electrodes when multiple pairs of electrodes deliver a sequence of IRE pulses in succession.

[0017] IRE pulse generators are configured to deliver peak powers in the tens of kilowatts range. However, IRE pulses strong enough to ablate tissue can also cause unwanted effects, potentially posing a clinical risk. For example, a pulse voltage of 2 kV across 200 Ω (both possible values) of tissue will instantaneously generate a local peak current of 10 A, or 20 kW, in the tissue between the two electrodes. This voltage, when applied between the electrodes to form a sequence of bipolar IRE pulses, may be high enough to generate sufficiently high Joule heating, which can produce char if not rapidly dissipated.

[0018] Embodiments of the invention described below provide techniques for IRE ablation (i.e., applying IRE pulses) over relatively large, contiguous areas of tissue without causing thermal damage to the electrodes and / or tissue due to electrode overheating. In some embodiments, a system including a switch assembly energizes different pairs of electrodes of a multi-electrode catheter and arranges the timing of the pairs so that the electrodes do not overheat while IRE is being applied to the tissue, yet still provide continuous, spatial ablation. Some embodiments provide a processor-controlled switch box (e.g., "switch assembly"). During application of IRE ablation power by the electrodes, the processor can control the switch box to switch between electrode pairs.

[0019] The energization of different electrode pairs (whether adjacent or non-adjacent) and the time required for Joule heating to dissipate are predetermined within the protocol (e.g., by an algorithm). In particular, electrode pairs are not used sequentially. For example, the protocol may specify that bipolar IRE pulses be applied to pairs of electrodes in an order in which successive activations of a given electrode pair are interleaved. In other words, activation of at least one other electrode pair should occur between successive activations of a given electrode pair. Such a protocol ensures that any two activations of the same electrode pair are separated in time (i.e., temporally gapped) by at least a predetermined duration. The time gap may range from 0.2 microseconds to 20 microseconds, and may typically be 5 microseconds.

[0020] In yet another embodiment, the protocol is optimized to sequentially energize electrode pairs (i.e., interleaved activation) around the entire circumference of the loop head catheter to perform IRE ablation around the entire circumference of a lumen, such as the ostium of a PV.

[0021] The term "approximately" used in connection with any numerical value or range of values ​​herein indicates a reasonable dimensional tolerance that enables a portion of a component or a collection of components to function for its intended purpose as described herein. More specifically, "approximately" may refer to a range of values ​​of ±20% of the recited value; for example, "approximately 90%" may refer to a range of values ​​of 71% to 99%.

[0022] In another embodiment, the distance between the electrodes of each pair is the same across all pairs. By maintaining the same inter-electrode distance for each electrode pair, the processor maintains a uniform field strength across the lesion as long as the pulse is the same. The inter-electrode distance between electrode pairs can range from 0.5 mm to 15 mm, and is typically 3.5 mm.

[0023] The disclosed sequential IRE ablation method is applicable to many types of multi-electrode catheters, including expensive frame catheters such as balloon or basket catheters. This technique is also applicable to loop catheters such as the Lasso™ catheter and multi-arm catheters such as the PentaRay™ catheter (both manufactured by Biosense Webster, Irvine, California). Catheters of other shapes can also be used with the disclosed technique, such as those with deflectable tips carrying one-dimensional arrays of electrodes or flat catheters carrying two-dimensional arrays of electrodes. The electrodes themselves may have any shape suitable for bipolar IRE ablation (e.g., flat or ring).

[0024] Typically, the processor is programmed with software containing specific algorithms that enable the processor to perform each of the processor-related steps and functions outlined above.

[0025] By sequencing electrode-pair bipolar IRE ablation according to a predetermined protocol (e.g., an algorithm), the disclosed sequenced multi-electrode IRE ablation technique can provide safer and more effective IRE ablation procedures.

[0026] System Description 1 is a schematic, depiction of a catheter 21-based position tracking and irreversible electroporation (IRE) ablation system 20, in accordance with an embodiment of the present invention. System 20 comprises a deflectable tip section 40, shown in inset 25, fitted to a distal end 22a of a shaft 22 of catheter 21, which comprises a plurality of electrodes 50 (seen in detail in FIG. 2). In the embodiment described herein, electrodes 50 are used for IRE ablation of tissue in the left atrium of heart 26, such as for IRE ablation of pulmonary vein ostia 51 within heart 26.

[0027] The proximal end of catheter 21 is connected to a control console 24 that includes an ablation power supply 45. Console 24 includes a switch box 46 (also called a switch assembly) that can energize any one or more electrode pairs between electrodes 50. A sequenced IRE ablation protocol utilizing an embodiment of the disclosed method, as shown in FIG. 3, is stored in memory 48 of console 24.

[0028] A physician 30 inserts the distal end 22a of the shaft 22 through the sheath 23 and into the heart 26 of a patient 28 lying on a table 29. The physician 30 navigates the distal end of the shaft 22 to a target location within the heart 26 by manipulating the shaft 22 using a manipulator 32 near the proximal end of the catheter and / or deflection from the sheath 23. During insertion of the distal end 22a, the deflectable tip section 40 is maintained in a straight, constrained configuration by the sheath 23. By containing the tip section 40 in a straight configuration, the sheath 23 also serves to minimize vascular trauma along the path to the target location.

[0029] When the distal end 22a of the shaft 22 reaches the target location, the physician 30 retracts the sheath 23, expands the tip portion 40, and further manipulates the shaft 22 to position the electrode 50 disposed on the tip portion 40 in contact with the ostium 51 of the pulmonary vein.

[0030] The electrodes 50 are connected by wires that extend through the shaft 22 to a processor 41 that controls a switch box 46 of an interface circuit 44 in the console 24 .

[0031] In an embodiment, processor 41 receives a measured electrical impedance signal between electrode 50 and surface electrode 38, as seen in the illustrated system attached by wires extending through cable 37 to the chest of patient 28. Methods for tracking the position of electrode 50 using measured impedance have been implemented in various medical applications, for example, in the CARTO™ system manufactured by Biosense-Webster (Irvine, California), and are described in detail in U.S. Patent Nos. 7,756,576, 7,869,865, 7,848,787, and 8,456,182, the disclosures of which are all incorporated herein by reference. This method is sometimes referred to as Advanced Catheter Location (ACL). Console 24 drives display 27, which shows the tracked position and / or shape of deflectable tip 40 within heart 26.

[0032] As further shown in inset 25, distal end 22a includes a magnetic position sensor 39 contained within distal end 22a just proximal to tip portion 40. During navigation of distal end 22a within heart 26, console 24 receives signals from magnetic sensor 39 in response to magnetic fields from external magnetic field generator 36, for example, to measure the position of tip portion 40 within the heart and, optionally, to present the tracked position on display 27. Magnetic field generator 36 is positioned at a known location external to patient 28, such as, for example, beneath patient table 29. Console 24 also includes a driver circuit 34 configured to drive magnetic field generator 36.

[0033] Position sensing methods using external magnetic fields have been implemented in various medical applications, for example, in the CARTO™ system manufactured by Biosense-Webster, and are described in detail in U.S. Pat. Nos. 5,391,199, 6,690,963, 6,484,118, 6,239,724, 6,618,612, and 6,332,089, WO 96 / 05768, and U.S. Patent Publication Nos. 2002 / 0065455(A1), 2003 / 0120150(A1), and 2004 / 0068178(A1), the disclosures of which are all incorporated herein by reference.

[0034] Processor 41, shown included in control console 24, is typically a general-purpose computer with suitable front-end and interface circuitry 44 for receiving signals from catheter 21 and delivering RF energy treatment via catheter 21 within the left atrium of heart 26, as well as controlling other components of system 20. Processor 41 typically includes software in memory 48 of system 20 that is programmed to perform the functions described herein. The software may be downloaded to the computer in electronic form, for example, over a network, or alternatively or additionally, may be provided and / or stored on a non-transitory tangible medium, such as magnetic, optical, or electronic memory. In particular, processor 41 executes the dedicated algorithms disclosed herein, included in FIG. 4, which enable processor 41 to perform the steps of the present disclosure, as further described below.

[0035] Selecting continuous electrodes during IRE Figure 2 is a schematic side depiction of the multi-electrode deflectable tip section 40 of the catheter 21 of Figure 1, in accordance with an exemplary embodiment of the present invention. The deflectable tip section 40, which is shown straight but can assume a bent or even looped configuration, has ten electrodes 50, designated e1 through e10, disposed on the section 40.

[0036] Using the switch assembly 46 of the system 20, one or more IRE pulses can be delivered from the IRE ablation power supply 45 of the system 20 independently to each electrode pair selected from the ten electrodes, as predetermined by an algorithm such as that shown schematically in Figure 3. In the illustrated exemplary embodiment, electrode pairs e1-e2 (50a), e4-e5 (50b), and e6-e7 (50c) are selected to be energized to deliver the IRE pulses. Thus, rather than sequentially activating pairs e1-e2, e2-e3, e3-e4, e4-e5, e5-e6, and e6-e7, with current flowing through electrodes e2, e3, e4, e5, and e6, with no cooling time in between, pairs e1-e2, e4-e5, e6-e7, and then pairs e2-e3, e5-e6, and e3-e4 can be sequenced so that each electrode 50 has time to cool before being used again for IRE ablation. Pairs may be energized sequentially, or groups of electrodes may be energized together (e.g., e1-e2 and e6-e7, e4-e5, and e2-e3, e5-e6, and e3-e4). The above description assumes that adjacent electrodes are energized. However, the electrodes may be paired in other ways, for example e1-e4, e2-e5, e3-e6, e4-e7.

[0037] 3 is a schematic front view of sequenced energization of electrode pairs of the multi-electrode deflectable tip section 40 of the catheter deployed in the form of a loop 404, in accordance with an exemplary embodiment of the present invention. FIG. 3 may schematically represent a front view of the aforementioned Lasso™ catheter being deployed at the ostium of a PV.

[0038] In FIG. 3, each concentric ring 60 represents, for example, a duration during the refractory period of the cardiac cycle during which selected electrodes are energized to deliver an IRE bipolar pulse.

[0039] In one embodiment, the pulses are applied synchronously with the heartbeat, i.e., gated to be applied during the tissue's refractory period. Ventricular and atrial electrograms at a ventricular or atrial tissue location are typically acquired by electrodes in contact with the tissue on a location catheter, for example, during electrophysiological mapping of the respective wall tissue portion of the respective heart chamber. The ventricular or atrial refractory period is the duration of the pause in neural activity at the tissue location after activation occurs in the tissue of either of the heart chambers. Typically, the refractory period approximately coincides with the QRST interval portion of the cardiac cycle evidenced in the ventricular or atrial electrogram taken at that location. The refractory period can be intentionally induced in a cardiac tissue portion, for example, using a pacing catheter that paces the tissue at the tissue location.

[0040] The duration numbers 1 through 6 (e.g., cardiac cycle numbers 1, 2, 3, 4, 5, and 6) and their respective identities of the electrode pairs energized during the refractory period of each cardiac cycle are listed in Table I below.

[0041] [Table 1]

[0042] As can be seen in the figure, each electrode is energized four times over six durations, with a pause between every two consecutive energizations (i.e., e1 pause 61, e2 pause 62, e3 pause 63, e4 pause 64, e5 pause 65, e6 pause 66, e7 pause 67, e8 pause 68, e9 pause 69, e10 pause 70).

[0043] The dark circle (77) represents the arc of tissue around the circumference of the ostium that underwent IRE ablation. As can be seen, the entire ostium was IRE ablated twice during the 6-period (heartbeat) IRE procedure.

[0044] By way of example, the pulses applied in each cardiac cycle may be specified by Table II below.

[0045] [Table 2]

[0046] The side depiction shown in Figure 3 is chosen as an example, as other illustrative embodiments are possible. For example, in another embodiment, arc portion 77 is longer and represents a bipolar voltage applied between two adjacent electrodes (e.g., every third electrode), such as e1-e3, e2-e4, e3-e5, etc., generating partially spatially overlapping electric fields.

[0047] In another exemplary embodiment, only a single electrode pair is activated at any given time. In this case, the protocol in Table I can be replaced by the protocol shown in Table III below, with each cycle specifying a single electrode pair to be activated alone.

[0048] [Table 3]

[0049] In yet another exemplary embodiment, at least some of the bipolar IRE pulses are applied between non-adjacent electrodes. In yet another exemplary embodiment, at least some of the bipolar IRE pulses are applied between groups of electrodes that are shorted together (e.g., between e1, e2, e3 shorted together and e6, e7, e8 shorted together, or between e1, e2, e3, e4, and e9 shorted together), as opposed to individual pairs of electrodes, such as between e2 and e3.

[0050] 4 is a flow chart that schematically illustrates a method for using the electrode pairs of the catheter head of FIG. 2 for sequential irreversible electroporation (IRE) ablation, according to an exemplary embodiment of the present invention. The algorithm executes a process that begins at IRE protocol selection step 82 when physician 30 selects an IRE protocol that includes sequenced activation of electrode pairs of a multi-electrode catheter, such as pair of electrodes 50 of catheter 21, according to the exemplary embodiment presented. Example protocols are provided above by Tables I and II.

[0051] Next, physician 30 inserts, navigates, and positions a catheter at a target location within the patient's lumen, such as at ostium 51, in a balloon catheter positioning step 84.

[0052] Finally, physician 30 uses system 20 using the IRE protocol to apply IRE pulses (e.g., according to the sequence in Table I) according to the sequence specified in the protocol to non-sequentially energize each of the electrode pairs in a sequenced IRE ablation step 86.

[0053] The example flowchart shown in Figure 4 has been selected solely for conceptual clarity. In alternative embodiments, processor 41 may perform additional steps, such as monitoring the measured electrode temperatures and acting accordingly as necessary, such as disconnecting overheated electrode pairs from further use in a specified protocol.

[0054] Although the embodiments described herein primarily address pulmonary vein isolation, the methods and systems described herein can also be used for other applications that may require sequenced ablation, such as renal denervation, and generally for ablation of other organs, such as for the treatment of lung or liver cancer.

[0055] It will therefore be understood that the above-described embodiments are cited by way of example, and that the present invention is not limited to what has been particularly shown and described above. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described in the foregoing specification, as well as variations and modifications thereof that would occur to one skilled in the art upon reading the foregoing description, but which are not disclosed in the prior art. Documents incorporated by reference into this patent application shall be considered solely as defined herein and shall be considered part of this application, except to the extent that any term in such incorporated document is defined inconsistently with a definition expressly or impliedly given herein.

[0056] [Embodiment] (1) An irreversible electroporation (IRE) method, comprising: placing a plurality of electrodes of the catheter in contact with tissue of the organ; generating a bipolar IRE pulse; ablating the tissue by applying the bipolar IRE pulses to the electrode pairs according to a sequence in which successive activations of a given electrode pair are interleaved with activations of at least one other electrode pair and are separated in time by at least a predetermined duration. (2) The method of embodiment 1, wherein applying the bipolar IRE pulse comprises applying the bipolar IRE pulse between adjacent electrodes. (3) The method of embodiment 1, wherein applying the bipolar IRE pulse comprises applying at least a portion of the bipolar IRE pulse between non-adjacent electrodes. (4) The method of embodiment 1, wherein applying the bipolar IRE pulse comprises applying at least a portion of the bipolar IRE pulse between a pair of electrodes. (5) The method of embodiment 1, wherein the electrode pairs have the same inter-electrode distance.

[0057] (6) The method of embodiment 1, wherein the tissue includes cardiac tissue and applying the bipolar IRE pulse includes gating the bipolar IRE pulse to synchronize it with a refractory period of the cardiac tissue. (7) An irreversible electroporation (IRE) system, comprising: a catheter having a plurality of electrodes configured to be placed in contact with tissue of an organ; an IRE ablation power supply configured to generate bipolar IRE pulses; and a processor configured to ablate the tissue by applying the bipolar IRE pulses to the electrode pairs according to a sequence in which successive activations of a given electrode pair are interleaved with activations of at least one other electrode pair and are spaced apart in time by at least a predetermined duration. (8) The system of embodiment 7, wherein the processor is configured to apply the bipolar IRE pulse between adjacent electrodes. (9) The system of embodiment 7, wherein the processor is configured to apply at least a portion of the bipolar IRE pulse between non-adjacent electrodes. (10) The system of embodiment 9, wherein the processor is configured to apply at least a portion of the bipolar IRE between a pair of electrodes.

[0058] (11) The system of embodiment 7, wherein the electrode pairs have the same inter-electrode distance. (12) The system of embodiment 7, wherein the tissue includes cardiac tissue and the processor is configured to gate the bipolar IRE pulse to synchronize with the refractory period of the cardiac tissue. (13) The system of embodiment 7, further comprising a switching assembly configured to switch the IRE ablation power source between the electrode pairs, and wherein the processor is configured to apply the bipolar IRE pulses according to the sequence by controlling the switching assembly.

Claims

1. 1. An irreversible electroporation (IRE) system comprising: a catheter having a plurality of electrodes configured to be placed in contact with tissue of an organ; an IRE ablation power supply configured to generate bipolar IRE pulses; a processor configured to apply the bipolar IRE pulses to the electrode pairs in an activation sequence to ablate the tissue, wherein activation of a given electrode pair is separated in time by a predetermined time to allow for cooling time, with activation of at least one other electrode pair between each further activation of the given electrode pair; Including, The system further comprises a processor configured to monitor the measured temperatures of the plurality of electrodes and to interrupt activation of the pair of electrodes based on the measured temperatures of the plurality of electrodes.

2. The system of claim 1 , wherein the processor is configured to apply the bipolar IRE pulse between adjacent electrodes that comprise the given electrode pair.

3. The system of claim 1 , wherein the processor is configured to apply at least a portion of the bipolar IRE pulse between non-adjacent electrodes that comprise the given electrode pair.

4. The system of claim 3 , wherein the processor is configured to apply at least a portion of the bipolar IRE pulse between pairs of electrodes comprising a plurality of the electrodes.

5. The system of claim 1 , wherein the given electrode pair has the same inter-electrode distance as the other electrode pairs.

6. The system of claim 1 , wherein the tissue includes cardiac tissue, and the processor is configured to gate the bipolar IRE pulse to synchronize with a refractory period of the cardiac tissue.

7. 2. The system of claim 1, further comprising a switching assembly configured to switch the IRE ablation power source between the given electrode pair and the at least one other electrode pair, and wherein the processor is configured to apply the bipolar IRE pulses according to the activation sequence by controlling the switching assembly.

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