Patent Description:
A wide range of medical procedures involve placing probes, such as catheters, within a patient's body. Location sensing systems have been developed for tracking such probes. Magnetic location sensing is one of the methods known in the art. In magnetic location sensing, magnetic field generators are typically placed at known locations external to the patient. A magnetic field sensor within the distal end of the probe generates electrical signals in response to these magnetic fields, which are processed to determine the coordinate locations of the distal end of the probe. These methods and systems are described in <CIT><CIT><CIT><CIT><CIT>and <CIT>, in <CIT>, and in <CIT> and <CIT> and <CIT>. Locations may also be tracked using impedance or current based systems.

One medical procedure in which these types of probes or catheters have proved extremely useful is in the treatment of cardiac arrhythmias. Cardiac arrhythmias and atrial fibrillation in particular, persist as common and dangerous medical ailments, especially in the aging population.

Diagnosis and treatment of cardiac arrhythmias include mapping the electrical properties of heart tissue, especially the endocardium, and selectively ablating cardiac tissue by application of energy. Such ablation can cease or modify the propagation of unwanted electrical signals from one portion of the heart to another. The ablation process destroys the unwanted electrical pathways by formation of non-conducting lesions. Various energy delivery modalities have been disclosed for forming lesions, and include the use of microwave, laser and more commonly, radiofrequency energies to create conduction blocks along the cardiac tissue wall. In a two-step procedure, mapping followed by ablation, electrical activity at points within the heart is typically sensed and measured by advancing a catheter containing one or more electrical sensors into the heart, and acquiring data at a multiplicity of points. These data are then utilized to select the endocardial target areas at which the ablation is to be performed.

Electrode catheters have been in common use in medical practice for many years. They are used to stimulate and map electrical activity in the heart and to ablate sites of aberrant electrical activity. In use, the electrode catheter is inserted into a major vein or artery, e.g., femoral vein, and then guided into the chamber of the heart of concern. A typical ablation procedure involves the insertion of a catheter having a one or more electrodes at its distal end into a heart chamber. A reference electrode may be provided, generally taped to the skin of the patient or by means of a second catheter that is positioned in or near the heart. RF (radio frequency) current is applied through the tip electrode(s) of the ablating catheter, and current flows through the media that surrounds it, i.e., blood and tissue, between the tip electrode(s) and an indifferent electrode. The distribution of current depends on the amount of electrode surface in contact with the tissue as compared to blood, which has a higher conductivity than the tissue. Heating of the tissue occurs due to its electrical resistance. The tissue is heated sufficiently to cause cellular destruction in the cardiac tissue resulting in the formation of a lesion within the cardiac tissue which is electrically non-conductive.

Irreversible electroporation (IRE) applies short electrical pulses that generate high enough electrical fields (typically greater than <NUM> Volts per centimeter) to irreversibly damage the cells. Non-thermal IRE may be used in treating different types of tumors and other unwanted tissue without causing thermal damage to surrounding tissue. Small electrodes are placed in proximity to target tissue to apply short electrical pulses. The pulses increase the resting transmembrane potential, so that nanopores form in the plasma membrane. When the electricity applied to the tissue is above the electric field threshold of the target tissue, the cells become permanently permeable from the formation of nanopores. As a result, the cells are unable to repair the damage and die due to a loss of homeostasis and the cells typically die by apoptosis.

Irreversible electroporation may be used for cardiac ablation as an alternative to other cardiac ablation techniques, e.g., radio frequency (RF) cardiac ablation. Irreversible electroporation cardiac ablation is sometimes referred to as Pulse Field Ablation (PFA). As IRE is generally a low thermal technique, IRE may reduce the risk of collateral cell damage that is present with the other techniques. e.g., in RF cardiac ablation.

<CIT> describes an apparatus including an interface and a processor. The interface is configured to receive one or more magnetic-positioning signals from one or more position sensors coupled to one or more body-surface patches attached to a body of a patient, the magnetic-positioning signals indicative of respective positions of the position sensors.

<CIT> describes a phrenic nerve pacing monitor assembly for a cryogenic balloon catheter system which is used during a cryoablation procedure, which monitors movement of a diaphragm of a patient, including a pacing detector and a safety system.

Embodiments are set out in the dependent claims.

Irreversible electroporation (IRE) is generally performed by applying electrical pulse trains in a bipolar fashion between two electrodes or two sub-sets of electrodes that are in contact with tissue of a body part (e.g., a heart chamber) of a patient. When the probe inserted into the body part is a focal catheter with a single ablation electrode, the above bipolar IRE is impossible. Therefore, unipolar IRE may be performed by applying electrical pulse trains between an electrode situated in the body part and one or more body-surface patches attached to the skin of the chest and/or back and/or leg etc. of the patient.

When performing unipolar IRE, the low equivalent capacitance of the patient (about <NUM> nano Farads (nF)) makes regulation of the electroporation difficult, because of the associated high impedance. In bipolar IRE, i.e., between two local electrodes, the equivalent capacitance is about <NUM> nF. Another problem with unipolar IRE is the fact that the effect of the IRE current is distributed through the patient (in bipolar IRE, the current is localized between the two local electrodes).

Embodiments of the present invention, solve the above problems by operating an IRE ablation power generator to produce pulse trains having a high pulse frequency in a range of <NUM> megahertz (MHz) to <NUM>, and typically about <NUM>. The high frequency counteracts the low capacitance of the patient. However, IRE at such a high frequency is not as efficient as IRE at lower frequencies, which are typically of the order of <NUM> kilohertz (kHz). To counteract the loss of efficiency, and also to compensate for the problem of current distribution described above, the IRE generator is configured to generate pulses having an amplitude in a range of <NUM> to <NUM> kilovolt (kV), and typically about <NUM> kV, and is able to deliver currents in a range of <NUM> to <NUM> Amps, and typically about <NUM> Amps. The voltage and current of the pulse trains may depend on the impedance between the electrode(s) and patch(es), for example, based on the size of the electrode(s) and patch(es) and distance between the electrode(s) and patch(es).

Each of the pulse trains may have any suitable length, with each of the pulse trains having the same length or different lengths. For example, a pulse train may have a length in a range of <NUM> to <NUM> microseconds with a delay between pulse trains in a range of <NUM> milliseconds to <NUM> second. The delay between the pulse trains may be fixed or variable.

The pulse trains may be monophasic or biphasic and have any suitable duty cycle. In some embodiments, there may be a gap between adjacent pulses. For example, the positive pulse may have a length equal to <NUM> percent of a period (of a waveform in the trains), the negative pulse may have a length equal to <NUM> percent of the period, while the gap after each pulse may be equal to <NUM> percent of the period. In some embodiments, there may be no gap between adjacent pulses. The positive pulses and negative pulses may have the same absolute amplitude or different absolute amplitudes. The pulses may have any suitable shape, for example, square, triangular, trapezoidal, or sine wave.

Unipolar IRE may also be used with multielectrode catheters for example to perform multiple simultaneous ablations, e.g., along a line. Unipolar IRE, whether using a focal catheter or one or more electrodes of a multielectrode catheter, may provide a deeper ablation lesion than bipolar IRE as the pulse trains in unipolar IRE are applied through the tissue from the body part to the skin surface of the patient.

The size and/or number of electrodes and/or body-surface patches may affect the IRE ablation process. If the body-surface patch is (or patches are) too small, the current from the electrical pulse trains may be too concentrated on the skin area leading to damage (e.g., heat damage) of the skin as well as leading to a weak current density at the tissue of the body part which results in poor ablation. Therefore, large patches (e.g., standard patches used for RF ablation) are generally more desirable for unipolar IRE to prevent skin damage as well as to provide a higher concentration of current density at the tissue of the body part. However, larger patches may lead to stimulating muscles too much. Muscle stimulation is generally not a problem with RF ablation which uses lower power and a continuous signal. However, higher power pulse trains may lead to muscle stimulation depending on the size and location of the body-surface patches.

Embodiments of the present invention solve the above problems by allowing one or more different electrodes of a multielectrode catheter (e.g., a balloon or lasso-shape catheter) to be selected by the physician, and one or more body-surface patches to be selected (by the physician or automatically) as the return electrode(s) in order to find a combination of electrodes and patches that keep muscle stimulation within acceptable limits. In some embodiments, the ablation electrode may be part of a focal catheter including a single ablation electrode.

In some embodiments, the body-surface patches may be selected so as to minimize muscle stimulation. For example, one or two patches closest to the catheter or around the catheter (e.g., symmetrically around the body on the chest and back) may be selected and a test pulse train is (or trains are) applied between the catheter electrode(s) and the selected body-surface patches. Movement of the body (e.g., chest or leg) may then be measured to provide a measure of muscle stimulation. If the movement is within a given threshold, the selected body-surface patches are used for future ablations until the movement exceeds the given threshold. If the movement exceeds the given threshold, different or more body-surface patches are selected, e.g., randomly or according to a protocol. Another test pulse train is (or trains are) applied, and the resulting body movement is measured. If the movement exceeds the given threshold, different or more body-surface patches are selected, e.g., randomly or according to the protocol, etc..

The test pulse trains may be applied, and the body movement measured pre-treatment and/or during treatment (e.g., between ablations or even between pulse trains of the same ablation location) as the body movement may depend on proximity of the catheter and/or patches to nerves etc..

Reference is now made to <FIG>, which is a schematic pictorial illustration of a catheter-based position tracking and ablation system <NUM> in accordance with an exemplary embodiment of the present invention. Reference is also made to <FIG>, which is a schematic pictorial illustration of a balloon catheter <NUM>, in accordance with an embodiment of the present invention.

The position tracking and ablation system <NUM> is used to determine the position of the balloon catheter <NUM>, seen in an inset <NUM> of <FIG> and in more detail in <FIG>. The balloon catheter <NUM> includes a shaft <NUM> and an inflatable balloon <NUM> fitted at a distal end of the shaft <NUM>. Typically, the balloon catheter <NUM> is used for therapeutic treatment, such as spatially ablating cardiac tissue, for example at the left atrium. The catheter <NUM> is configured to be inserted in a chamber of a heart <NUM> of a living subject (e.g., a patient <NUM>).

The position tracking and ablation system <NUM> can determine a position and orientation of the shaft <NUM> of the balloon catheter <NUM> based on sensing-electrodes <NUM> (proximal-electrode 52a and distal-electrode 52b) fitted on the shaft <NUM>, on either side of the inflatable balloon <NUM> and a magnetic sensor <NUM> fitted just proximally to proximal-electrode 52a. The proximal-electrode 52a, the distal-electrode 52b, and the magnetic sensor <NUM> are connected by wires running through the shaft <NUM> to various driver circuitries in a console <NUM>. In some embodiments, the distal electrode 52b may be omitted. The magnetic sensor <NUM> may comprise a single axis sensor (SAS), or a double axis sensor (DAS), or a triple axis sensor (TAS), by way of example.

The shaft <NUM> defines a longitudinal axis <NUM> (<FIG>). A center-point <NUM> (<FIG>) on the axis <NUM>, which is the origin of the sphere shape of the inflatable balloon <NUM>, defines a nominal position of the inflatable balloon <NUM>. Multiple ablation electrodes <NUM> (only some labeled for the sake of simplicity) are disposed in a circumference over the inflatable balloon <NUM>, which occupy a large area as compared with sensing-electrodes 52a and 52b. Radio frequency power or IRE ablation signals may be supplied to the ablation electrodes <NUM> to ablate the cardiac tissue.

Typically, the disposed ablation electrodes <NUM> are evenly distributed along an equator of the inflatable balloon <NUM>, where the equator is generally aligned perpendicular to the longitudinal axis <NUM> of the distal end of the shaft <NUM>.

The illustration shown in <FIG> is chosen purely for the sake of conceptual clarity. Other configurations of sensing-electrodes <NUM> and ablation electrodes <NUM> are possible. Additional functionalities may be included in the magnetic sensor <NUM>. Elements which are not relevant to the disclosed embodiments of the invention, such as irrigation ports, are omitted for the sake of clarity.

A physician <NUM> navigates the balloon catheter <NUM> to a target location in the heart <NUM> of the patient <NUM> by manipulating the shaft <NUM> using a manipulator <NUM> near the proximal end of the catheter and/or deflection from a sheath <NUM>. The balloon catheter <NUM> is inserted, while the inflatable balloon <NUM> is deflated, through the sheath <NUM>, and only after the balloon catheter <NUM> is retracted from the sheath <NUM> is the inflatable balloon <NUM> inflated and regains its intended functional shape. By containing balloon catheter <NUM> in a deflated configuration, the sheath <NUM> also serves to minimize vascular trauma on its way to the target location.

Console <NUM> comprises a processor <NUM>, typically a general-purpose computer and a suitable front end and interface circuits <NUM> for generating signals in, and/or receiving signals from, body-surface patches <NUM> which are attached by wires running through a cable <NUM> and configured to be attached to the chest and to the back of the patient <NUM>. In some embodiments, the body-surface patches <NUM> provide position signals, as described in more detail below. The body-surface patches <NUM> may comprise respective electrodes <NUM>, and/or respective magnetic sensors <NUM>. Each magnetic sensor <NUM> may comprise a single axis sensor (SAS), or a double axis sensor (DAS), or a triple axis sensor (TAS), by way of example.

Console <NUM> further comprises a magnetic-sensing sub-system. The patient <NUM> is placed in a magnetic field generated by a pad containing magnetic field generator coils <NUM>, which are driven by a unit <NUM> disposed in the console <NUM>. The magnetic field generator coils <NUM> are configured to generate alternating magnetic fields is a region including the magnetic sensor <NUM> and the body-surface patches <NUM>. The magnetic fields generated by the coils <NUM> generate direction signals in the magnetic sensor <NUM> and the magnetic sensors <NUM>, which are then provided as corresponding electrical inputs to the processor <NUM>.

In some embodiments, the processor <NUM> uses the position-signals received from the sensing-electrodes <NUM>, the magnetic sensor <NUM> and the ablation electrodes <NUM> to estimate a position of the balloon catheter <NUM> inside an organ, such as inside a cardiac chamber. In some embodiments, the processor <NUM> correlates the position signals received from the electrodes <NUM>, <NUM> with previously acquired magnetic location-calibrated position signals, to estimate the position of the balloon catheter <NUM> inside a cardiac chamber. The position coordinates of the sensing-electrodes <NUM> and the ablation electrodes <NUM> may be determined by the processor <NUM> based on, among other inputs, measured impedances, or on proportions of currents distribution, between the electrodes <NUM>, <NUM> and the body-surface patches <NUM>. The console <NUM> drives a display <NUM>, which shows the distal end of the catheter position inside the heart <NUM>.

The method of position sensing using current distribution measurements and/or external magnetic fields is implemented in various medical applications, for example, in the Carto® system, produced by Biosense Webster Inc. (Irvine, California), and is described in detail in <CIT><CIT><CIT><CIT><CIT><CIT><CIT><CIT>and <CIT>, in <CIT>, and in <CIT>, <CIT> and <CIT>.

The Carto®<NUM> system applies an Active Current Location (ACL) impedance-based position-tracking method. In some embodiments, using the above noted ACL method, the processor <NUM> estimates the positions of the sensing-electrodes <NUM> and the ablation electrodes <NUM>. In some embodiments, the signals received from the electrodes <NUM>, <NUM> and/or the body-surface patches <NUM> are correlated with a matrix which maps impedance (or another electrical value) measured by the sensing-electrodes <NUM>, <NUM> and/or the body-surface patches <NUM> with a position that was previously acquired from magnetic location-calibrated position signals.

In some embodiments, to visualize catheters which do not include a magnetic sensor, the processor <NUM> may apply an electrical signal-based method, referred to as the Independent Current Location (ICL) method. In the ICL method, the processor <NUM> calculates a local scaling factor for each voxel of a volume of the balloon catheter <NUM>. The factor is determined using a catheter with multiple electrodes having a known spatial relationship, such as a Lasso-shaped catheter. However, although yielding accurate local scaling (e.g., over several millimeters), ICL may be less accurate when applied to a balloon catheter, whose size is on the order of centimeters. In some embodiments, the processor <NUM> may apply the disclosed ICL method to scale the balloon catheter shape into a correct one, based on known smaller scale distances between electrodes of a lasso-shaped catheter, as well as based on larger scale distances, themselves based on the known distance between the sensing-electrodes <NUM> at the ends of the inflatable balloon <NUM>.

Processor <NUM> is typically programmed in software 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.

The medical system <NUM> may also include an ablation power generator <NUM> (such as an RF or IRE signal generator) configured to be connected to the catheter <NUM>, and apply an electrical signal (or pulsed trains) between one or more of the electrodes <NUM> and one or more of the body-surface patches <NUM> to ablate tissue in the chamber of the heart.

The example illustration shown in <FIG> is chosen purely for the sake of conceptual clarity. <FIG> shows only elements related to the disclosed techniques for the sake of simplicity and clarity. System <NUM> typically comprises additional modules and elements that are not directly related to the disclosed techniques, and thus are intentionally omitted from <FIG> and from the corresponding description.

A balloon catheter is described herein by way of example only. The system <NUM> may be implemented using any suitable electrode catheter or probe having a distal end and one or more ablation electrodes disposed on the distal end, for example, a lasso catheter, a basket catheter, a grid catheter, or a focal catheter including a single ablation electrode.

Reference is now made to <FIG>, which is a schematic view of a body part <NUM> (e.g., the heart <NUM>) of a living subject <NUM> (e.g., the patient <NUM>) being ablated using unipolar electroporation in the system <NUM> of <FIG>.

<FIG> shows a probe <NUM> (e.g., the balloon catheter <NUM>) including a distal end <NUM> including one or more electrodes <NUM> inserted into the body part <NUM> of the living subject <NUM> and one or more body-surface patches <NUM> (only one shown for the sake of simplicity) configured to be applied to a skin surface <NUM> of the living subject <NUM>. The ablation power generator <NUM> is configured to be electrically connected to the electrode(s) <NUM> and the body-surface patch(es) <NUM>. The ablation power generator <NUM> is configured to generate multiple electrical pulse trains having a pulse frequency of at least <NUM> megahertz, with respective delays between the electrical pulse trains. The ablation power generator <NUM> is configured to apply the electrical pulse trains (having the pulse frequency of at least <NUM> megahertz) between the electrode(s) <NUM> and the body-surface patch(es) <NUM> so as to electroporate tissue of the body part <NUM>.

In some embodiments, the electrical pulse trains have a pulse frequency of about <NUM> megahertz. In other embodiments, the electrical pulse trains have a pulse frequency in a range between <NUM> and <NUM> megahertz. In some embodiments, the electrical pulse trains have a current of about <NUM> Amps. In other embodiments, the electrical pulse trains have a current in a range between <NUM> and <NUM> Amps. In some embodiments, the electrical pulse trains have a voltage of about <NUM> kilovolts. In other embodiments, the electrical pulse trains have a voltage in a range between <NUM> and <NUM> kilovolts.

Each of the pulse trains may have any suitable length, with each of the pulse trains having the same length or different lengths. The delay between the pulse trains may be fixed or variable. In some embodiments, each (or some) of the electrical pulse trains have a length in a range between <NUM> and <NUM> microseconds, with each of the respective delays having a length in a range between <NUM> milliseconds and <NUM> second.

Reference is now made to <FIG>, which is a schematic view illustrating selectively selecting body-surface patches <NUM> for use in electroporation in the system <NUM> of <FIG>. The physician <NUM> (<FIG>) may select one or more of the electrodes <NUM> for performing IRE ablation. Multiple electrodes <NUM> may be selected to perform a line ablation. The ablation power generator <NUM> is configured to be selectively electrically connected to one or more of the electrodes <NUM> and one or more of the body-surface patches <NUM>. <FIG> shows that pulse trains <NUM> are applied between the selected electrode(s) <NUM> and three upper body-surface patches <NUM>.

Reference is now made to <FIG>, which is a flowchart <NUM> including an unclaimed method of operation of the system <NUM> of <FIG>.

The processor <NUM> is configured to receive (block <NUM>) a user input (e.g., from the physician <NUM>) setting a movement threshold to determine if a present selection of body-surface patches <NUM> leads to too much muscle stimulation in response to applied pulse trains, described in more detail below. In some embodiments, a default movement threshold is used unless overridden by the physician <NUM>.

The processor <NUM> is configured to select (block <NUM>) one or more of the body-surface patches <NUM>. In some embodiments, the initial selected body-surface patches <NUM> may be selected by the body-surface patches <NUM> or according to a default sub-set of the body-surface patches <NUM>, or according to a position of the electrodes <NUM> selected for performing IRE ablation. For example, one or two body-surface patches <NUM> closest to the probe <NUM> or around the probe <NUM> (e.g., symmetrically placed around the body on the chest and back) may be selected. In some embodiments, the selected body-surface patches <NUM> may include at least one of the body-surface patches <NUM> attached to a chest of the living subject <NUM>, and at least one of the body-surface patches <NUM> attached to a back of the living subject <NUM>.

The ablation power generator <NUM> is configured to generate (block <NUM>) one or more electrical pulse train, and apply the electrical pulse train(s) between the electrode(s) <NUM> (selected by the physician <NUM>) and the selected body-surface patches <NUM>.

The processor <NUM> is configured to provide (block <NUM>) a measurement of movement (representative of distance, velocity, and/or acceleration) of the living subject <NUM> responsively to applying the electrical pulse train(s) between the electrode(s) <NUM> (selected by the physician <NUM>) and the selected body-surface patches <NUM>. The measurement of movement of the living subject <NUM> may be a measurement of chest movement or leg movement, for example, of the living subject <NUM>.

In some embodiments, one or more of the body-surface patches <NUM> are configured to provide one or more position signals. The processor <NUM> is configured to provide the measurement of movement responsively to the position signal(s). In some embodiments, the processor <NUM> is configured to compute the measurement of movement responsively to a measurement of displacement, and/or velocity, and/or acceleration of the chest movement responsively to one or more of the position signals. The velocity and acceleration may be computed based on analyzing the movement of the positions of the body-surface patches <NUM> over time. Alternatively, or additionally, the magnetic sensors <NUM> may provide signals indicative of acceleration of the body-surface patches <NUM>.

In some embodiments, the magnetic sensors <NUM> of the body-surface patches <NUM> are configured to provide respective position signals responsively to sensing the generated alternating magnetic fields generated by the magnetic field generator coils <NUM>. The processor <NUM> may be configured to compute the measurement of movement responsively to one or more of the position signals received from the magnetic sensors <NUM>.

In some embodiments, one or more of the position signals from the magnetic sensors <NUM> may be processed to compute the position(s) of the corresponding body-surface patch(es) <NUM>. The computed position(s) may then be used to compute the measurement of movement. For example, the computed positions may be summed, averaged or otherwise combined to compute the measurement of movement. The positions may be relative positions, for example, relative to an origin of a magnetic coordinate system, relative to an average position of the chest or diaphragm, or relative to some other given position. In the above computation, the position of the body-surface patch <NUM> closest to the diaphragm on the chest may be used. In some embodiments, the positions of a sub-set of the body-surface patches <NUM> closest to the diaphragm or other position on the chest or body may be used to compute the measurement of movement. In some embodiments, the computation may weight the computed positions of the (subset of) body-surface patches <NUM> according to the proximity of the corresponding body-surface patches <NUM> to the diaphragm or other position of the chest or body providing a higher weight to patches <NUM> that are closer to the diaphragm other position of the chest or body.

In some embodiments, the respective electrodes <NUM> of the body-surface patches <NUM> are configured to provide respective position signals. The electrodes <NUM> may detect signals provided by the catheter electrode(s) <NUM>, <NUM>, <NUM> and/or from other one or ones of the body-surface patches <NUM>, and/or from a reference electrode (not shown) placed in the heart <NUM> or on the back of the patient <NUM>, for example. The processor <NUM> may be configured to compute the measurement of movement responsively to one or more of the position signals received from the electrodes <NUM>. In some embodiments, the processor <NUM> may be configured to compute the measurement of movement responsively to one of the position signals received from one of the electrodes.

In some embodiments, the position signals from the electrodes <NUM> may then be used to compute positions of one or more of the body-surface patches <NUM>. One or more of the computed positions may then be used to compute the measurement of movement as described above with reference to the positions computed for the magnetic sensors <NUM>.

In some embodiments, a distribution of current or impedance values over the body-surface patch electrodes <NUM> may provide an indication of the measurement of movement. Therefore, the measurement of movement may be computed based on the distribution of the current or impedance values of all, or a subset of, the body-surface patch electrodes <NUM>.

The processor <NUM> is configured to check at decision block <NUM> if the measurement of movement exceeds the movement threshold. If the measurement of movement does not exceed the threshold (branch <NUM>), the steps of blocks <NUM> and <NUM> are repeated. In other words, if an ablation has been initiated or confirmed by the physician <NUM>, that ablation will continue with the same selection of body-surface patches <NUM> and movement of the patient <NUM> is intermittently checked. For example, the physician <NUM> may initiate an ablation including multiple pulse trains during which movement of the patient <NUM> is checked intermittently. If the measurement of movement does exceed the threshold (branch <NUM>), the processor <NUM> is configured select (block <NUM>) new ones of the body-surface patches <NUM> responsively to the measurement of movement of the living subject exceeding the threshold. The newly selected body-surface patches <NUM> are connected to the ablation power generator <NUM> and the steps of blocks <NUM>-<NUM> are repeated. In other words, if an ablation has been initiated or confirmed by the physician <NUM>, that ablation will continue with the newly selected body-surface patches <NUM> and movement of the patient <NUM> is intermittently checked. If ablation was not initiated, a new test pulse train is (or trains are) applied between the selected electrode(s) <NUM> and the newly selected body-surface patches <NUM> and movement of the patient <NUM> is checked again. Therefore, the ablation power generator <NUM> is configured to generate one or more additional electrical pulse trains, and apply the additional electrical pulse train(s) between the selected electrode(s) <NUM> and the newly selected body-surface patches <NUM>.

In some embodiments, the processor <NUM> is configured to select the newly selected body-surface patches <NUM> to include the previously selected body-surface patches <NUM> plus one or more additional ones of the body-surface patches <NUM>. In some embodiments, the processor <NUM> is configured to randomly select the newly selected body-surface patches <NUM>. In some embodiments, the processor <NUM> is configured to select the newly selected body-surface patches <NUM> such that the newly selected body-surface patches <NUM> are at least partially different to the previously selected body-surface patches <NUM>.

The electrical pulse trains described above may be applied as test pulse trains pre-treatment and/or as real time ablation pulse trains during treatment (e.g., between ablations or even between trains of the same ablation location) as the body movement may depend on proximity of the probe <NUM> and/or body-surface patches <NUM> to nerves etc..

When new body-surface patches <NUM> are selected between pulse trains (e.g., first pulse train(s) and second pulse train(s)) of the same ablation, the processor <NUM> is configured to select the new body-surface patches <NUM> while a given ablation location of the body part is being ablated so that the ablation power generator <NUM> is configured to generate the first electrical pulse train(s) and the second electrical pulse train(s) to ablate the given ablation location of the tissue of the body part.

When new body-surface patches <NUM> are selected between ablations, the ablation power generator <NUM> is configured to generate the first electrical pulse train(s) to ablate a first ablation location of tissue of the body part <NUM> and generate the second electrical pulse(s) train to ablate a second, different, ablation location of the tissue of the body part <NUM>.

More specifically, "about" or "approximately" may refer to the range of values ±<NUM>% of the recited value, e.g., "about <NUM>%" may refer to the range of values from <NUM>% to <NUM>%.

Various features of the invention which are, for clarity, described in the contexts of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment may also be provided separately or in any suitable sub-combination.

Claim 1:
An electroporation ablation system, comprising:
a probe (<NUM>) configured to be inserted into a body part of a living subject, and comprising a distal end including at least one electrode (<NUM>);
a plurality of body-surface patches (<NUM>) configured to be applied to a skin surface of the living subject;
an ablation power generator (<NUM>) configured to be selectively electrically connected to the at least one electrode (<NUM>) and at least one of the body-surface patches, and configured to generate at least one first electrical pulse train, and apply the at least one first electrical pulse train between the at least one electrode and at least a first one of the body-surface patches (<NUM>); and
a processor configured to:
provide a measurement of movement of the living subject responsively to applying the at least one first electrical pulse train between the at least one electrode and the at least first one of the body-surface patches (<NUM>); and
select at least a second one of the body-surface patches (<NUM>) responsively to the measurement of movement of the living subject, and wherein the ablation power generator is configured to generate at least one second electrical pulse train, and apply the at least one second electrical pulse train between the at least one electrode and the at least second one of the body-surface patches (<NUM>).