Patent Description:
Various systems have been proposed for radiofrequency (RF) ablation. For example, <CIT> describes an RF catheter probe comprising an insertion tube, and a distal end with a distal electrode, a force sensor to detect force on the distal electrode, and an irrigated electrode mounted on a coupling member of the force sensor, which has a tubular form surrounding a central space occupied by components, including force sensing coils. A fluid diverter that passes fluid to the proximal irrigated electrode is configured as an insert or an integrated projection of the coupling member. The fluid diverter has a proximal entry opening and a distal exit opening connected by a fluid passage with at least a radial branch and at least an axial branch. The irrigated electrode is mounted over the distal exit opening to receive fluid from the fluid passage.

International Patent Application Publication <CIT> describes a medical catheter and a radio frequency treatment system having said catheter. The catheter is provided with an annular end portion having a plurality of electrodes. The annular end portion is further provided with a force sensor. The force sensor is used to measure the contact force between the annular end portion and other objects, and assists in controlling contact between the annular end portion and vascular walls or organ surfaces.

European Patent Application Publication <CIT> describes a catheter system comprising an at least partially flexible catheter body, at least a ring electrode, and at least a strain gauge. The ring electrode surrounds at least a portion of the flexible catheter body. The strain gauge is allocated to the ring electrode and the strain gauge is configured to measure a deformation of the flexible catheter body at a position allocated to the ring electrode to detect a contact between the ring electrode and tissue.

Turning to irreversible electroporation, various techniques for controlling irreversible electroporation (IRE) procedures are known in the art.

For example, <CIT> describes an apparatus for localizing an electrical field for electroporation of tissue. The apparatus includes a pulsed DC electrical power supply and at least one catheter tip and electrode assembly configured for endocardial placement, such that electrodes positioned at separate endocardial locations allow development of an electrical field between the electrodes to effect electroporation of tissue in the electrical field.

<CIT> described methods, systems, and devices for enhancing the efficiency and efficacy of energy delivery and tissue mapping. One system includes a treatment element having a plurality of electrodes and an energy generator that is configured to deliver electric energy pulses to the electrodes in a variety of patterns. <CIT> describes endovascular catheters, configured for delivery to a carotid artery from a subclavian artery approach, for assessing, and treating patients having sympathetically mediated disease, involving augmented peripheral chemoreflex and heightened sympathetic tone by reducing chemosensor input to the nervous system via carotid body ablation. Pressure or force sensors may be incorporated into any of the catheters, for example they could be mounted to a flex circuit proximate an ablation element, and could be used to verify contact or indicate contact force. Diverging arms with open/close actuation could be actuated to a position that corresponds to a particular contact pressure range. Alternatively, a catheter could be "pushed" against the wall until contact pressure reaches a desired level. Alternatively, a baseline pressure may be chosen when a desirable contact force is visually confirmed, for example vessel distension caused by ablation element contact force may visually appear using an imaging modality such as angiography. A change of pressure or force, within an acceptable range from the baseline, measured by the sensors may indicate appropriate contact force and deviation from this range could indicate an inappropriate contact force. A computer algorithm that controls delivery of ablation energy may discontinue energy delivery if contact force deviates from the appropriate range.

An embodiment of the present invention that is described herein provides a system comprising a focal catheter including an insertion tube, first and second electrodes, and a contact-force sensor. The insertion tube is configured to insert the catheter into a patient body. The first and second electrodes are coupled to a distal-end of the catheter at a predefined distance from one another, and are configured to: (i) receive, via the insertion tube, one or more irreversible electroporation (IRE) pulses, and (ii) apply the IRE pulses, between the first and second electrodes, to tissue of the patient body. The contact-force sensor is disposed between the first and second electrodes and is configured to produce an electrical signal indicative of a contact force applied between the distal-end and the tissue. The system includes an IRE pulse generator (IPG) configured to supply the one or more IRE pulses; and a processor, which is configured, based on the electrical signal received from the contact-force sensor, to control the IPG to supply of the one or more IRE pulses to the first and second electrodes.

In some embodiments, the catheter includes at least a temperature sensor, which is coupled to the distal-end, and is configured to produce a temperature signal, indicative of a measured temperature of at least one of the distal-end and the tissue. In yet other embodiments, the temperature sensor includes a thermocouple.

In an embodiment, the processor is configured to: (i) hold a temperature threshold, and (ii) control the supply of the one or more IRE pulses to the first and second electrodes, based on a comparison between the measured temperature and the temperature threshold. In another embodiment, the catheter includes a focal catheter. In yet another embodiment, the first and second electrodes are coupled along an axis of the catheter.

There is additionally provided, in accordance with an embodiment of the present invention, a method for producing a focal catheter according to appended claim <NUM>.

Irreversible electroporation (IRE) may be used, for example, for treating arrhythmia by ablating tissue cells using high-voltage applied pulses. Cellular destruction occurs when the transmembrane potential exceeds a threshold, leading to cell death and formation of a lesion. In IRE-based ablation procedures, high-voltage bipolar electrical pulses are applied, for example, to a pair of electrodes in contact with tissue to be ablated, so as to form a lesion between the electrodes, and thereby to treat arrhythmia in a patient heart.

Embodiments of the present invention that are described hereinbelow provide improved techniques for controlling IRE ablation by controlling one or more IRE pulses applied to tissue, also referred to herein as target tissue, at an IRE ablation site.

In some cases, a focal catheter may be required to carry out an ablation procedure. In principle, in unipolar radiofrequency (RF) ablation, the focal catheter may comprise (i) a contact-force sensing device for estimating the contact force applied between the catheter and the target tissue, (ii) a large distal electrode for ablating the target tissue, and (iii) one or more ring electrodes for diagnostic measurements. This configuration, however, cannot be used for applying high-voltage bipolar IRE pulses, for example because: (a) the high proximity between the electrodes prevents applying such high-voltage bipolar pulses, and (b) at least one of the electrodes may be overheated in response to applying the high-voltage bipolar pulses.

According to the invention, a system configured to carry out a controlled IRE ablation comprises a focal catheter having an insertion tube, which is configured to insert the catheter into an ablation site in the patient's body, such as in the patient's heart. The catheter may comprise a pair of similar electrodes, also referred to herein as first and second electrodes, which are substantially wider than the aforementioned ring electrodes.

The first and second electrodes are coupled to the distal-end of the catheter at a predefined distance from one another, and are configured to: (i) receive, e.g., via the insertion tube, one or more IRE pulses produced by an IRE pulse generator (IPG), and (ii) apply the IRE pulses, between the first and second electrodes, to tissue at the ablation site.

The catheter comprises a contact-force sensor, which is disposed between the first and second electrodes and is configured to produce an electrical signal indicative of the contact force applied between the distal-end and the tissue.

In some embodiments, the catheter comprises one or more temperature sensors, which is coupled to the distal-end at one or more respective positions. Each temperature sensor is configured to produce a temperature signal, indicative of the measured temperature of at least one of the distal-end and the tissue.

In some embodiments, in an IRE ablation procedure, a physician inserts the distal-end into the ablation site and brings the first and second electrodes into contact with the target tissue. In some embodiments, during the IRE ablation, a processor of the system is configured to receive the signals indicative of the contact force applied between the distal-end and the target tissue, and the measured temperature. Based on the received signals, the processor is configured to assist the physician in controlling the IRE ablation, by controlling the contact force applied between the distal-end and the tissue, and parameters of the one or more pulses applied to the tissue. For example, (i) before applying one or more IRE pulses, the processor may alert the physician in case the contact between the distal-end and the tissue is not within a specified range of contact-force of the IRE procedure, (ii) during and after applying one or more pulses of IRE, the processor may check whether or not the temperature measured by the temperature sensors is within a specified range of temperatures of the IRE procedure.

In some embodiments, the processor may hold a temperature threshold and compare between the measured temperature and the temperature threshold, such that in case the measured temperature exceeds the temperature threshold, the processor may alert the physician to, or may autonomously, control the IPG to stop applying IRE pulses to the tissue.

The disclosed techniques improve the control of IRE ablation, and thereby, improve the patient safety and reduce the duration of IRE ablation procedures.

<FIG> is a schematic, pictorial illustration of a catheter <NUM> based position-tracking and irreversible electroporation (IRE) ablation system <NUM>, in accordance with an embodiment of the present invention. Catheter <NUM> comprises a focal-type IRE ablation catheter.

In some embodiments, system <NUM> comprises a tip section <NUM>, which is deflectable or non-deflectable, and is fitted at a distal-end 22a of a shaft <NUM> of catheter <NUM> with tip section <NUM> comprising multiple electrodes <NUM> as illustrated in inset <NUM>.

In the embodiment described herein, electrodes <NUM> are configured for IRE ablation of tissue of left atrium of a heart <NUM>, such as IRE ablation of an ostium <NUM> of a pulmonary vein in heart <NUM>. Electrodes <NUM> may additionally be used to sense intra-cardiac (IC) electrocardiogram (ECG) signals. Note that the techniques disclosed herein are applicable, mutatis mutandis, to other sections (e.g., atrium or ventricle) of heart <NUM>, and to other organs of a patient <NUM>.

In some embodiments, the proximal end of catheter <NUM> is connected to a control console <NUM> (also referred to herein as a console <NUM>) comprising an ablative power source, in the present example an IRE pulse generator (IPG) <NUM>, which is configured to deliver peak power in the range of tens of kW. Console <NUM> comprises a switching box <NUM>, which is configured to switch the power applied by IPG <NUM> to one or more selected pairs of electrodes <NUM>. A sequenced IRE ablation protocol may be stored in a memory <NUM> of console <NUM>.

In some embodiments, a physician <NUM> inserts distal-end 22a of shaft <NUM>, e.g., using an insertion tube of shaft <NUM> that is configured for inserting catheter <NUM>, through a sheath <NUM> into heart <NUM> of patient <NUM> lying on a table <NUM>. Physician <NUM> navigates distal-end 22a of shaft <NUM> to a target location in heart <NUM> by manipulating shaft <NUM> using a manipulator <NUM> near the proximal end of catheter <NUM> and/or deflection from sheath <NUM>. During the insertion of distal-end 22a, tip section <NUM> is maintained in a straightened configuration by sheath <NUM>. By containing tip section <NUM> in a straightened configuration, sheath <NUM> also serves to minimize vascular trauma when physician <NUM> moves catheter <NUM>, through the vasculature of patient <NUM>, to the target location, such as an ablation site in heart <NUM>.

Once distal-end 22a of shaft <NUM> has reached the ablation site, physician <NUM> retracts sheath <NUM> and, in case of a deflectable tip section, deflects tip section <NUM>, and further manipulates shaft <NUM> to place electrodes <NUM> disposed over tip section <NUM> in contact with ostium <NUM> at the ablation site.

In some embodiments, electrodes <NUM> are connected by wires running, through the aforementioned insertion tube of shaft <NUM>, to a processor <NUM>, which is configured to control switching box <NUM> of interface circuits <NUM> in console <NUM>.

Reference is now made to the inset <NUM>. In some embodiments, distal-end 22a comprises a position sensor <NUM> of a position tracking system, which is coupled to distal-end 22a, e.g., at tip section <NUM>. In the present example, position sensor <NUM> comprises a magnetic position sensor, but in other embodiments, any other suitable type of position sensor (e.g., other than magnetic-based) may be used. During navigation of distal-end 22a in heart <NUM>, processor <NUM> of console <NUM> receives signals from magnetic position sensor <NUM> in response to magnetic fields from external field generators <NUM>, for example, for the purpose of measuring the position of tip section <NUM> in heart <NUM> and, optionally, displaying the tracked position overlaid on the image of heart <NUM>, on a display <NUM> of console <NUM>.

Reference is now made back to the general view of <FIG>. In some embodiments, magnetic field generators <NUM> are placed at known positions external to patient <NUM>, e.g., below table <NUM>. Console <NUM> also comprises a driver circuit <NUM>, configured to drive magnetic field generators <NUM>.

The method of position sensing using external magnetic fields is implemented in various medical applications, for example, in the CARTO™ system, produced by Biosense Webster Inc. (Irvine, Calif. ) and is described in detail in <CIT>,<CIT>,<CIT>, <CIT>, <CIT>and<CIT>, in <CIT>, and in <CIT>, <CIT> and<CIT>.

Typically, processor <NUM> of console <NUM> comprises a general-purpose processor of a general-purpose computer, with suitable front end and interface circuits <NUM> for receiving signals from catheter <NUM>, as well as for applying ablation energy via catheter <NUM> in a left atrium of heart <NUM> and for controlling the other components of system <NUM>. Processor <NUM> typically comprises a software in memory <NUM> of system <NUM>, which is programmed to carry out the functions described herein. The software may be downloaded to the computer in electronic form, over a network, for example, or it may, alternatively or additionally, be provided and/or stored on non-transitory tangible media, such as magnetic, optical, or electronic memory.

Irreversible electroporation (IRE), also referred to as Pulsed Field Ablation (PFA), may be used as a minimally invasive therapeutic modality to for forming a lesion (e.g., killing tissue cells) at the ablation site by applying high-voltage pulses to the tissue. In the present example, IRE pulses may be used for killing myocardium tissue cells in order to treat cardiac arrhythmia in heart <NUM>. Cellular destruction occurs when the transmembrane potential exceeds a threshold, leading to cell death and thus the development of a tissue lesion. Therefore, of particular interest is the use of high-voltage bipolar electrical pulses, e.g., using a pair of electrodes <NUM> in contact with tissue at the ablation site, to generate high electric fields (e.g., above a certain threshold) to kill tissue cells located between the electrodes.

In the context of this disclosure, "bipolar" voltage pulse means a voltage pulse applied between two electrodes <NUM> of catheter <NUM> (as opposed, for example, to unipolar pulses that are applied, e.g., during a radio-frequency ablation, by a catheter electrode relative to some common ground electrode not located on the catheter).

To implement IRE ablation over a relatively large tissue region of heart <NUM>, such as a circumference of an ostium of a pulmonary vein (PV) or any other suitable organ, it is necessary to use multiple pairs of electrodes <NUM> of catheter <NUM>, or any other suitable type of IRE catheter, having multi electrodes <NUM> in tip section <NUM>. To make the generated electric field as spatially uniform as possible over a large tissue region it is best to have pairs of electrodes <NUM> selected with overlapping fields, or at least fields adjacent to each other. However, there is a Joule heating component that occurs with the IRE generated fields, and this heating may damage the electrodes when multiple pairs of electrodes <NUM> are continuously used for delivering a sequence of IRE pulses.

In an embodiment, system <NUM> comprises surface electrodes <NUM>, shown in the example of <FIG>, as attached by wires running through a cable <NUM> to the chest and shoulder of patient <NUM>. In some embodiments, surface electrodes <NUM> are configured to sense body-surface (BS) ECG signals in response to beats of heart <NUM>. Acquisition of BS ECG signals may be carried out using conductive pads attached to the body surface or any other suitable technique. As shown in <FIG>, surface electrodes <NUM> are attached to the chest and shoulder of patient <NUM>, however, additional surface electrodes <NUM> may be attached to other organs of patient <NUM>, such as limbs.

In some embodiments, electrodes <NUM> are configured to sense intra-cardiac (IC) ECG signals, and (e.g., at the same time) surface electrodes <NUM> are sensing the BS ECG signals. In other embodiments, sensing the IC ECG signals may be sufficient for performing the IRE ablation, so that surface electrodes <NUM> may be applied for other use cases.

In some embodiments, physician <NUM> may couple at least a pair of electrodes <NUM> to tissue, also referred to herein as target tissue, at the ablation site in heart <NUM>. The target tissue is intended to be ablated by applying one or more IRE pulses via electrodes <NUM>. Note that the IRE pulses may be applied to the target tissue multiple times, e.g., during different stages of the IRE ablation procedure.

Reference is now made back to an inset <NUM>. According to the invention, , tip section <NUM>, which is fitted at distal-end 22a of catheter <NUM>, comprises a pair of first and second electrodes <NUM>, referred to herein as electrodes 50A and 50B, respectively. Electrodes 50A and 50B are coupled to tip section <NUM> of distal-end 22a, at a predefined distance from one another.

In some embodiments, electrodes 50A and 50B are similar to one another, and are relatively wide, e.g., larger than about <NUM> along an axis <NUM> of tip section <NUM> of catheter <NUM>. In the present example, electrodes 50A and 50B are disposed along axis <NUM>, which is a longitudinal axis of catheter <NUM>. In other embodiments, electrodes 50A and 50B may be disposed, relative to one another, at any suitable positions in distal-end 22a and may have any suitable predefined distance between one another. For example, at least one of electrodes 50A and 50B may be disposed at the edge of tip section <NUM>.

In the context of the present disclosure and in the claims, the terms "about" or "approximately" for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components, or a physical parameters such as speed and time, to function for its intended purpose as described herein.

Tip section <NUM> of distal-end 22a comprises a contact-force sensor <NUM>, which is disposed between the first and second electrodes, in the present example, electrodes 50A and 50B, respectively. Contact-force sensor <NUM> is configured to produce an electrical signal indicative of a contact force applied between tip section <NUM> of distal-end 22a, and the aforementioned tissue located at the ablation site of heart <NUM>.

In other embodiments, one or more contact-force sensors <NUM> may be coupled to tip section <NUM> of distal-end 22a, in addition to contact-force sensor <NUM> shown in inset <NUM>, at any other suitable respective locations.

In some embodiments, tip section <NUM> of distal-end 22a comprises at least a temperature sensor <NUM>, which is coupled to distal-end 22a, and is configured to produce a temperature signal, indicative of a measured temperature of at least one of distal-end 22a and the tissue ablated at the target location. In some embodiments, tip section <NUM> may comprise multiple temperature sensors <NUM> disposed at respective multiple positions of distal-end 22a. For example, in addition to temperature sensor <NUM> shown in inset <NUM> for measuring the temperature of the aforementioned tissue, tip section <NUM> may comprise two additional temperature sensors <NUM>, coupled to distal-end 22a in close proximity to electrodes 50A and 50B, so as to measure the temperature of both electrodes 50A and 50B.

In some embodiments, temperature sensor <NUM> may comprise a thermocouple (TC), but in other embodiments, at least one temperature sensor <NUM> may comprise and other suitable type of a temperature sensing device.

Reference is now made back to the general view of <FIG>. Processor <NUM> is configured to receive the aforementioned electrical signal from contact-force sensor <NUM>. Based on the electrical signal, processor <NUM> is configured to control IPG <NUM> to supply the one or more IRE pulses to electrodes 50A and 50B. In the context of the present disclosure and in the claims, processor <NUM>
is configured to control, based on the received electrical signal, one or more parameters of the IRE pulses applied to the tissue. For example, based on the sensed contact force applied during the IRE ablation, between distal-end 22a and the tissue, processor <NUM> may control the energy, and/or amplitude and/or frequency of the applied IRE pulses. Moreover, processor <NUM> is configured to display, e.g., on display <NUM>, a message or any other type of display, indicative of the sensed contact force, so that physician <NUM> may adjust the applied contact force, e.g., by slightly pushing or retracting distal-end 22a relative to the tissue at the ablation site.

In some embodiments, processor <NUM> is configured to hold at least a temperature threshold, and to control the supply of the one or more IRE pulses, e.g., to electrodes 50A and 50B, based on a comparison between the temperature measured by temperature sensor <NUM> and the temperature threshold.

This particular configuration of system <NUM> is shown by way of example, in order to illustrate certain problems that are addressed by embodiments of the present invention and to demonstrate the application of these embodiments in enhancing the performance of such an IRE ablation system. Embodiments of the present invention, however, are by no means limited to this specific sort of example system, and the principles described herein may similarly be applied to other sorts of ablation systems provided they fall within the scope of the appended claims.

<FIG> is a flow chart that schematically illustrates a method for producing an IRE focal catheter having contact-force sensor <NUM> and temperature sensor <NUM>, in accordance with an embodiment of the present invention. The method begins at an electrodes coupling step <NUM>, with coupling electrodes 50A and 50B to distal-end 22a of an IRE catheter, such as catheter <NUM>. In some embodiments, electrodes 50A and 50B are fitted at a predefined distance from one another, and are configured for applying IRE pulses to the target tissue at the ablation site of heart <NUM>, or to tissue any other organ in the body of patient <NUM>.

At a contact-force sensor disposing step <NUM>, contact-force sensor <NUM> is disposed and fitted on tip section <NUM> of distal-end 22a, between electrodes 50A and 50B. As described in inset <NUM> of <FIG> above, contact-force sensor <NUM> is configured for sensing the contact force applied between distal-end 22a and the target tissue of heart <NUM>, and to produce the electrical signal indicative of the sensed contact force.

At a temperature sensor coupling step <NUM>, one or more temperature sensors <NUM> are coupled to tip section <NUM> of distal-end 22a, at predefined positions, so as to measure the temperature and to produce the temperature signal indicative of the sensed temperature, as described in <FIG> above.

At a processor coupling step <NUM> that terminates the method, distal-end 22a is coupled, via catheter <NUM>, to processor <NUM> of console <NUM>. In some embodiments, in step <NUM>, processor <NUM> is electrically connected to several components of catheter <NUM>, such as but not limited to: contact-force sensor <NUM>, one or more temperature sensors <NUM>, and position sensor <NUM>.

<FIG> is a flow chart that schematically illustrates a non-claimed method for controlling one or more IRE pulses applied to target tissue of heart <NUM>, based on signals indicative of contact-force and temperature measured during IRE ablation procedure, using a system in accordance with an embodiment of the present invention.

The method begins at an IRE catheter insertion step <NUM>, with inserting tip section <NUM>, which is located at distal-end 22a of catheter <NUM>, into the ablation site in heart <NUM> and bringing the pair of electrodes 50A and 50B into contact with the target tissue. As described in <FIG> above, tip section <NUM> comprises at least electrodes 50A and 50B, configured to receive IRE pulses from IPG <NUM> and to apply the IRE pulses to the target tissue of heart <NUM>. In some embodiments, tip section <NUM> further comprises one or more contact-force sensors <NUM>, and one or more temperature sensors <NUM>, such as thermocouples or any other suitable type of one or more temperature sensing devices.

At a contact-force signal receiving step <NUM>, processor <NUM> receives the electrical signal, which is indicative of the contact force applied between distal-end 22a and the target tissue of heart <NUM>. In case the measured contact force is not within the specified level thereof (e.g., between about <NUM> gram force (grf) and <NUM> grf), processor <NUM> may display, e.g., on display <NUM>, a message to physician to adjust the contact force applied between distal-end 22a, having electrodes 50A and 50B, and target tissue. In other embodiments, in case the measured contact force is not within the contact-force specified level, the processor may prevent the physician from applying the IRE pulses to the tissue.

At an IRE pulse applying step <NUM>, after verifying that the applied contact force is within the specified level of the IRE procedure, processor <NUM> controls IPG <NUM> to produce one or more IRE pulses. As described in <FIG> above, electrodes 50A and 50B are configured to receive the one or more IRE pulses from IPG <NUM>, and to apply, between electrodes 50A and 50B one or more bipolar IRE pulse to the target tissue. In some embodiments, processor <NUM> is configured to receive from one or more temperature sensors <NUM> one or more temperature signals indicative of the temperature measured, by temperature sensors <NUM>, during the IRE ablation procedure. The measured temperature may comprise tissue temperature, electrodes temperature and temperature of any other component of catheter <NUM>.

At a first decision step <NUM>, physician <NUM> checks whether or not the IRE ablation has been completed. If yes, the method proceeds to a catheter retracting step <NUM>, with physician retracting distal-end 22a of catheter <NUM> out of heart <NUM>, and the IRE procedure is concluded.

If the IRE ablation has not been completed, at a second decision step <NUM>, processor <NUM> compares between the temperature measured at step <NUM>, and a temperature threshold that processor <NUM> holds, as described in <FIG> above. Based on the comparison, processor <NUM> checks whether or not the measured temperature exceeds the temperature threshold. If the measured temperature exceeds the temperature threshold, the method proceeds to a pulse-level adjusting step <NUM>, in which processor <NUM> and/or physician <NUM> may adjust the number of IRE pulse applied to tissue, or reduce the number of pulses in a train, or reduce the temperature at the measured location. For example, the temperature may be reduced by waiting for a few millisecond more between trains and/or by applying irrigation (not shown) for cooling the ablated tissue and/or electrodes 50A and 50B.

Note that, based on the disclosed techniques, temperature control can be performed without modifying the IRE pulse voltage. In contrast to the IRE procedure, when applying unipolar RF power, control is typically performed by modifying the amplitude of the signal. In the present invention, however, lowering the amplitude in IRE ablation is undesirable because the voltage is key for obtaining the ablation effect.

In some embodiments, the overall energy applied to tissue may be reduced by modifying the number of pulses, and/or increasing time interval between sets of IRE pulses (also referred to herein as trains), and/or controlling the number of trains of IRE pulses applied to tissue. By using one of, or any suitable combination of these power control techniques, the electrode and/or tissue heating is prevented even without using irrigation.

In case, at step <NUM>, the measured temperature is lower than the temperature threshold, the method loops back to step <NUM> for starting a new set of contact-force and temperature measurements, and for applying additional one or more IRE pulses to the target tissue until the IRE ablation is completed.

Claim 1:
A system comprising:
an irreversible electroporation pulse generator (IPG) (<NUM>); a focal catheter (<NUM>), comprising:
an insertion tube, which is configured to insert the catheter (<NUM>) into a patient body;
first and second electrodes (<NUM>), which are coupled to a distal-end of the catheter (<NUM>) at a predefined distance from one another, and are configured to: (i) receive, via the insertion tube, one or more irreversible electroporation (IRE) <NUM>. pulses produced by the IPG, and (ii) apply the IRE pulses, between the first and second electrodes (<NUM>), to tissue of the patient body;
a contact-force sensor (<NUM>), which is disposed between the first and second electrodes (<NUM>) and is configured to produce an electrical signal indicative of a contact force applied between the distal-end of the catheter and the tissue; and the system further comprising
a processor (<NUM>), which is configured, based on the electrical signal received from the contact-force sensor (<NUM>), to control the IPG to supply the one or more IRE pulses to the first and second electrodes (<NUM>).