Timing of pulsed field ablation energy delivery

Abstract

Methods and systems for ablating cardiac tissue are disclosed. An example method includes monitoring an electrical signal of a heart of a patient. The electrical signal is indicative of a positive beat of the heart. The method further includes determining, with an electronic processor and based on the electrical signal, an end-of-diastole period at the end of a diastole period during which diastole of the heart has occurred during a previous cardiac cycle. The method also includes determining, with the electronic processor and based on the electrical signal, that another cardiac cycle has started. The method further includes causing, with the electronic processor, an electrode to deliver pulsed field ablation (PFA) energy to the heart during at least a portion of a time at which the end-diastolic period of the other cardiac cycle is expected to occur.

Description

Technical Field

[0001] The present technology generally relates to methods and systems for treating tissue using electroporation or pulsed field ablation. Background Art

[0002] There are many medical treatments involving examples of cutting, ablating, coagulating, destroying or otherwise changing the physiological properties of tissue. These techniques can be beneficially used to change the electrophysiological properties of tissue, such as those properties associated with cardiac arrhythmias or other electrophysiological abnormalities. In particular, the normal sinus rhythm of the heart begins at the sinoatrial node ("SA node"), which produces a depolarization wavefront that causes the adjacent myocardial tissue cells in the atrium to depolarize. The depolarization propagates across the atrium, causing the atrium to contract and emptying blood from the atrium into the ventricle. The pulse is then delivered to the myocardial tissue cells of the ventricle via the atrioventricular node ("AV node") and the His-Purkinje system. The depolarization of the cells propagates across the ventricle, causing the ventricle to contract. This conduction system produces the described, organized myocardial contraction sequence, resulting in a normal heartbeat.

[0003] Sometimes, anatomical obstacles such as fibrosis, fibrotic scars, or uneven distribution of myocardial cell refractoriness in certain heart parts in the atrium or ventricle can lead to abnormal conduction pathways in cardiac tissue, which can destroy the normal path of depolarization events. These anatomical obstacles or "conduction blocks" can cause electrical impulses to degenerate into several cyclic wavelets that circulate around the obstacles. Abnormal conduction pathways produce abnormal, irregular and sometimes life-threatening heart rhythms, known as arrhythmias. Arrhythmias can occur in the atrium, for example, as in atrial tachycardia, atrial fibrillation ("AF") or atrial flutter. Arrhythmias can also occur in the ventricle, for example, as in ventricular tachycardia. Additionally, there may be ectopic sites in the heart, which produce premature activation from such tissue sites, thereby producing arrhythmogenic conduction patterns. For example, ectopic sites in the pulmonary veins are one of the key mechanisms for inducing and maintaining atrial fibrillation.

[0004] One approach for treating arrhythmias includes creating one or more lesions that isolate abnormal pathways and direct electrical conduction along selected pathways to promote organized signal conduction, while also isolating AF triggers from contra-atrial connections. Often, the application of energy is used to destroy cells at the ablation site while leaving the surrounding structures of the organ substantially intact. Radiofrequency ("RF") energy and cryogenic cooling have been found to be highly feasible in this regard and are commonly employed. Other ablation techniques include the application of ultrasound, microwaves, lasers, cytotoxic agents (e.g., alcohol), and the like. Yet another ablation technique includes applying energy in the form of a pulsed electric field (PEF), which may also be referred to as pulsed field ablation (PFA). Summary of the invention

[0005] Pulsed field ablation (PFA) is a term used to explain the application of energy in the form of a pulsed electric field (PEF) via an electroporation mechanism (e.g., irreversible electroporation and reversible electroporation) to ablate cardiac tissue (i.e., create lesions). The electric field and the lesions created by the electric field can depend on many factors, including but not limited to the applied voltage, electrode configuration, pulse waveform, pulse train, and proximity of the electrodes to the target tissue.

[0006] The technology disclosed herein is generally directed to timing cardiac cycle-based PFA energy delivery to control (and increase or maximize) lesion depth and transmurality achieved by pulsed field ablation. Specifically, PFA energy can be delivered during a certain point in the cardiac cycle during diastole (and particularly during the end-diastolic period) to corresponding specific areas of the heart where PFA energy is delivered (via electrodes on a catheter) to increase or maximize lesion depth and / or thereby achieve transmural lesions.

[0007] In one example, the present disclosure provides a method for ablating cardiac tissue. The method may include monitoring an electrical signal of a patient's heart. The electrical signal indicates that the heart is beating. The method may also include determining, using an electronic processor and based on the electrical signal, an end-diastolic period, the end-diastolic period being at the end of a diastolic period in which diastole of the heart has occurred during a previous cardiac cycle. The method may also include determining, using the electronic processor and based on the electrical signal, that another cardiac cycle has begun. The method may also include causing an electrode to deliver pulsed field ablation (PFA) energy to the heart using the electronic processor during at least a portion of the time when the end-diastolic period of the other cardiac cycle is expected to occur.

[0008] In another aspect, determining the end-diastolic period includes determining, using the electronic processor and based on the electrical signal, a first time interval between occurrences of a first wave and a second wave included in the electrical signal of one or more previous cardiac cycles.

[0009] In another aspect, determining that another cardiac cycle has begun includes determining, using the electronic processor and based on the electrical signal, that another instance of the first wave has occurred in the current cardiac cycle.

[0010] In another aspect, causing the electrode to deliver the PFA energy to the heart includes: based on the first time interval, using the electronic processor, causing the electrode to deliver the PFA energy to the heart during at least a portion of the time when the end-diastolic period of the current cardiac cycle is expected to occur.

[0011] In another aspect, the first wave and the second wave are the same type of wave, and the first time interval occurs between successive occurrences of the first type of wave included in the electrical signal.

[0012] In another aspect, the first time interval comprises an RR interval and the first type of wave comprises an R wave.

[0013] In another aspect, the method further comprises selecting a type of the first type of wave based on a location of a treatment site of the heart intended to receive the PFA energy.

[0014] In another aspect, the first wave is a first type of wave and the second wave is a second type of wave different from the first type of wave.

[0015] In another aspect, the first type of wave comprises a P wave, and the second type of wave comprises an R wave, and the first time interval comprises a PR interval.

[0016] In another aspect, the method further includes selecting the first type of wave, the second type of wave, or both based on the location of a treatment site of the heart intended to receive the PFA energy.

[0017] In another aspect, determining the first time interval includes: determining a time value for each of a plurality of first time intervals included in the electrical signal during an evaluation period prior to delivering the PFA energy; determining a change between the time values; comparing the change to a change threshold; and in response to determining that the change is below the change threshold, establishing the first time interval by determining an average of the time values.

[0018] In another aspect, the evaluation period is longer when the heart of the patient is not artificially paced than when the heart of the patient is artificially paced.

[0019] In another aspect, the method further includes determining, with the electronic processor, that the end-diastolic period is expected to occur during a time period within a range of 90% to 99% of the first time interval after the another instance of the first type of wave occurs.

[0020] In another aspect, the diastole of the heart includes one of left ventricular diastole, right ventricular diastole, left atrial diastole, and right atrial diastole.

[0021] In another aspect, the end-diastolic period of the other cardiac cycle indicates that: during at least a portion of the time when the end-diastolic period of the other cardiac cycle is expected to occur, the myocardium included in the treatment site of the heart intended to receive the PFA energy has a minimum thickness compared to the thickness of the myocardium throughout the remainder of the other cardiac cycle.

[0022] In another embodiment, the present disclosure provides a system for ablating cardiac tissue. The system may include a generator, the generator including an electronic processor, and the electronic processor may be configured to monitor an electrical signal of a patient's heart. The electrical signal indicates that the heart is beating. The electronic processor may be further configured to determine an end-diastolic period based on the electrical signal, the end-diastolic period being at the end of a diastolic period in which diastolic relaxation of the heart has occurred during a previous cardiac cycle. The electronic processor may be further configured to determine that another cardiac cycle has begun based on the electrical signal. The electronic processor may be further configured to cause an electrode to deliver pulsed field ablation (PFA) energy to the heart during at least a portion of the time during which the end-diastolic period of the other cardiac cycle is expected to occur.

[0023] In another aspect, the electronic processor is configured to determine the end-diastolic period by determining, based on the electrical signal, a first time interval between occurrences of a first wave and a second wave included in the electrical signal of one or more previous cardiac cycles.

[0024] In another aspect, the electronic processor is configured to determine that another cardiac cycle has begun by determining, based on the electrical signal, that another instance of the first wave has occurred in the current cardiac cycle.

[0025] In another aspect, the electronic processor is configured to cause the electrode to deliver the PFA energy to the heart by causing the electrode to deliver the PFA energy to the heart during at least a portion of the time when the end-diastolic period of the current cardiac cycle is expected to occur, based on a first time interval.

[0026] In another aspect, the electronic processor is configured to determine that the end-diastolic period is expected to occur during a time within a range of 90% to 99% of the first time interval after another instance of the first type of wave occurs.

[0027] In another aspect, the diastole of the heart includes one of left ventricular diastole, right ventricular diastole, left atrial diastole, and right atrial diastole.

[0028] In another aspect, the end-diastolic period of the other cardiac cycle indicates that: during at least a portion of the time when the end-diastolic period of the other cardiac cycle is expected to occur, the myocardium included in the treatment site of the heart intended to receive the PFA energy has a minimum thickness compared to the thickness of the myocardium throughout the remainder of the other cardiac cycle.

[0029] In another example, the present disclosure provides a method for ablating cardiac tissue. The method may include monitoring an electrical signal of a patient's heart. The electrical signal indicates that the heart is beating. The method may also include determining, with an electronic processor and based on the electrical signal, a first time interval between the occurrence of a first wave and a second wave included in the electrical signal of one or more previous cardiac cycles. The method may also include determining, with the electronic processor and based on the electrical signal, another instance that the first wave has appeared in a current cardiac cycle. The method may also include causing an electrode to deliver pulsed field ablation (PFA) energy to the heart using the electronic processor during at least a portion of the time included in the range of 90% to 99% of the first time interval after the first wave has appeared in the current cardiac cycle.

[0030] In another aspect, the time included in the range of 90% to 99% of the first time interval after the first wave has appeared indicates that: during at least a portion of the time included in the range of 90% to 99% of the first time interval after the first wave has appeared, the myocardium included in the treatment site of the heart intended to receive the PFA energy has a minimum thickness compared to the thickness of the myocardium throughout the remainder of the current cardiac cycle.

[0031] The details of one or more aspects of the present disclosure are set forth in the following drawings and description. Other features, objectives, and advantages of the techniques described in the present disclosure will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 An example ablation system including a pulsed field ablation device having an example distal curvilinear electrode array portion according to one example is shown.

[0033] Figure 2 Based on an example Figure 1 Block diagram of the generator of the ablation system.

[0034] Figure 3 A number of graphs are shown of different known measurements and characteristics of an example heart throughout an example known cardiac cycle (ie, heartbeat) according to one example.

[0035] Figure 4A and Figure 4B A simplified diagram of an example electric field applied to myocardium of varying thicknesses is shown according to one example.

[0036] Figure 5 Shown by Figure 2 A flow chart of a method executed by an electronic processor of a generator to control the delivery of pulsed field ablation energy to a patient's heart. DETAILED DESCRIPTION

[0037] The present application provides methods and systems for diagnosing and / or treating undesirable physiological or anatomical tissue regions, such as those that contribute to abnormal electrical pathways in the heart. Referring now to the drawings, in which like reference numerals refer to like elements, examples of medical systems constructed according to the principles of the present invention are shown in FIG. Figure 1 , and generally designated as "10". The system 10 generally includes a medical device 12 that can be directly coupled to an energy supply device (e.g., a pulsed field ablation (PFA) generator 14) that includes an energy control, delivery system, and monitoring system. In some aspects, the medical device 12 can be indirectly coupled to the energy supply device via a catheter electrode distribution system 13. A remote controller 15 can also be included that communicates with the generator 14 for operating and controlling various functions of the generator 14. The medical device 12 can generally include one or more diagnostic or treatment areas for energy, therapeutic, and / or investigative interactions between the medical device 12 and a treatment site. The treatment area can deliver, for example, pulsed electroporation energy to a tissue area near the treatment area. Figure 1 One or more of the devices shown in the apparatus may be combined into a single device. For example, the catheter electrode distribution system / box 13 may not be present, and its functionality may be combined with the generator 14 and / or remote controller 15 into a single system / box.

[0038] The medical device 12 may include an elongated body 16, such as a catheter, sheath, or intravascular introducer, that can be passed through the vasculature of a patient and / or can be positioned proximate to a tissue area to be diagnosed or treated. The elongated body 16 may define a proximal portion 18 and a distal portion 20, and may also include one or more lumens disposed within the elongated body 16, thereby providing mechanical, electrical, and / or fluid communication between the proximal portion 18 of the elongated body 16 and the distal portion 20 of the elongated body 16. The distal portion 20 may generally define one or more treatment regions of the medical device 12 that are operable to monitor, diagnose, and / or treat a portion of a patient. The treatment region may have a variety of configurations to facilitate such operations. In some cases, the distal portion 20 (which is located at the distal portion 20) may have a plurality of configurations to facilitate such operations. Figure 110A to 110H (shown in an enlarged scale in FIG. 10B ) includes a catheter / elongated structure 112 carrying a plurality of electrodes 110A to 110H (collectively referred to as "electrodes 110"). The catheter 112 may include a distal portion 106 and a proximal portion 108. The electrode 110 may generally be positioned at the distal portion 106, while the proximal portion 108 may ultimately be connected to the catheter electrode distribution system 13. The electrode 110 may be configured to deliver pulsed field energy. For example, the generator 14 (e.g., the electronic processor 205 of the generator 14) may cause one or more of the electrodes 110 to provide / deliver PFA energy using one or more different modes (such as a focused mode). For example, in order to operate the electrode 110 in a focused mode, the generator 14 may output energy to the electrode 110 so that the electrode 110 generates a field having a geometry focused at the distal portion / tip 106 of the catheter 112 (e.g., focused at the tip electrode 110A). Such a focused field geometry may result in the formation of a lesion proximal to the tip 106 of the catheter 112. As used herein, causing the electrode 110 to provide / deliver PFA energy means controlling the generator 14 (e.g., the electronic processor 205 of the generator 14) to generate waveforms that are transmitted to the electrode 110 using the catheter 112 to provide / deliver PFA energy via the electrode 110, as described herein. The electrode 110 may have any suitable geometry. Example geometries of the electrode include, but are not necessarily limited to, a circular (e.g., annular) electrode surrounding the body of the lead, a conformable electrode, a hoop-shaped electrode, a segmented electrode (e.g., an electrode disposed at different circumferential positions around the lead, rather than a continuous annular electrode), and any combination thereof (e.g., annular electrodes and segmented electrodes). The electrode 110 may be distributed axially along the longitudinal axis LA of the catheter 112. Figure 1 The catheter 112 and electrodes 110 shown in are merely examples. In some instances, the catheter 112 may include more or fewer electrodes 112. Additionally or alternatively, the electrodes 110 may be arranged in different configurations, including the use of coils or other return electrodes. In some instances, the catheter 112 may be of different shapes at the point where the catheter 112 contacts the patient's tissue. The system may also be designed to vector energy in a unipolar configuration (between the electrode 110 and a return patch (not shown) located on the patient's skin). Further, the system may also be designed to vector energy in a dual catheter configuration (between one or any number of electrodes 110 and another indwelling catheter having a return electrode (not shown)).

[0039] The system 10 may also include three or more electrocardiogram (ECG) electrodes 26 configured to be placed in or on the patient and configured to communicate with the generator 14 through the catheter electrode distribution box 13 to monitor the patient's cardiac activity for determining the timing of pulse train delivery at a desired portion of the cardiac cycle, as explained in more detail below. In addition to monitoring, recording or otherwise transmitting measurements or conditions within the medical device 12 or the surrounding environment at the distal portion of the medical device 12, additional measurements may be made through connection with the multi-electrode catheter, including, for example, temperature in the generator 14 and / or the medical device 12, electrode-tissue interface impedance, delivered charge, current, power, voltage, work, etc. The surface ECG electrodes 26 may communicate with the generator 14 for initiating or triggering one or more alerts or therapeutic deliveries during operation of the medical device 12. In some instances, additional or alternative information is used to monitor patient information, such as cardiac cycle and timing. For example, the system 10 may receive intracardiac electrogram (EGM) information and / or other information from one or more other electrodes and / or devices / sensors. An additional neutral electrode patient ground patch (not shown) may be employed to assess the expected bipolar electrical path impedance, as well as monitor and alert the operator when an inappropriate and / or unsafe condition is detected, including, for example, inappropriate (excessive or insufficient) delivery of charge, current, power, voltage, and work performed by the plurality of electrodes 110; inappropriate and / or excessive temperature of the plurality of electrodes 110; inappropriate electrode-tissue interface impedance; assessing the integrity of the tissue electrical path by delivering one or more low voltage test pulses, and improper and / or unintentional electrical connection to the patient prior to delivering high voltage energy.

[0040] The generator 14 may include a current or pulse generator having a plurality of output channels, wherein each channel is coupled to an individual electrode of the plurality of electrodes 110 or a plurality of electrodes 110 of the medical device 12. The generator 14 may operate in one or more operating modes, including, for example: (i) bipolar energy delivery between at least two electrodes 110 or conductive portions of the medical device 12 in the patient's body; (ii) monopolar / unipolar energy delivery to one or more of the electrodes 110 or conductive portions on the medical device 12 in the patient's body and through a second device (not shown) in the body or a patient return or ground electrode (not shown) spaced apart from the plurality of electrodes 110 of the medical device 12 (such as on the patient's skin or on an auxiliary device positioned in the patient's body remote from the medical device 12); and (iii) a combination of monopolar and bipolar modes.

[0041] Generator 14 can provide electric pulse to medical device 12 to perform electroporation procedure to other tissues in cardiac tissue or body (for example, excitable tissues such as skeletal / smooth muscle tissue). "Electroporation" utilizes high amplitude pulse to complete physiological modification (i.e., permeabilization) of the cell to which energy is applied. Such pulses can preferably be short (e.g., nanosecond, microsecond or millisecond pulse width) to allow application of high voltage, high current (e.g., 20 amperes or more amperes) without causing long duration current flow of significant tissue heating and neuromuscular stimulation (e.g., phrenic nerve). In particular, pulse energy induces formation of microscopic pores or defects in cell membranes. Depending on the characteristics of the electric pulse, electroporated cells can survive (i.e., "reversible electroporation") or die (i.e., irreversible electroporation, "IEP") after electroporation. Reversible electroporation can be used to transmit reagents (including macromolecules) to target cells for various purposes, including changing the action potential of cardiomyocytes. The methods, systems, and devices described herein can be used to perform irreversible electroporation or reversible electroporation.

[0042] The generator 14 can be configured and programmed to deliver a pulsed, high voltage electric field suitable for achieving the desired pulsed, high voltage ablation (or pulsed field ablation). As a reference point, the pulsed, high voltage, non-RF ablation effects of the present disclosure can be distinguished from DC current ablation and thermally induced ablation that accompanies conventional RF techniques. For example, the pulse trains delivered by the generator 14 are delivered at a lower frequency than RF therapy. The pulsed field energy according to the present disclosure is sufficient to induce cell death so as to completely block abnormal conduction pathways along or through cardiac tissue, thereby destroying the ability of the cardiac tissue so ablated to propagate or conduct cardiac depolarization waveforms and associated electrical signals.

[0043] The plurality of electrodes 110 may also perform diagnostic functions, such as collecting intracardiac electrograms (EGMs) and performing selective pacing of intracardiac sites for diagnostic purposes. In one configuration, the measured ECG signals are transmitted from the catheter electrode energy distribution system 13 to an electrophysiology (EP) recording system input box (not shown) included with the generator 14. The plurality of electrodes 110 may also monitor proximity to target tissue and quality of contact with such tissue using impedance-based measurements of the connection to the catheter electrode energy distribution system 13. The catheter electrode energy distribution system 13 may include a high-speed relay to disconnect / reconnect a particular electrode 110 from the generator 14 to the generator during therapy. Immediately after the pulse energy is delivered, the relay reconnects the electrodes 110 so that they can be used for diagnostic purposes.

[0044] In some aspects, the plurality of electrodes 110 can deliver therapeutic biphasic pulses having a preprogrammed pattern and duty cycle, as explained in U.S. Pat. No. 10,531,914, which is incorporated by reference. In some aspects, when a plurality of electrodes 110 are delivered from a bipolar electrode array such as Figure 1 When delivered with an array as shown in FIG. 1 , the pulse train can produce lesions in the myocardium in the range of about 2 mm to 3 mm deep, 4 mm to 7 mm deep, etc. Changing the parameters of the pulse train (e.g., voltage, current, pulse width, number of pulses per pulse train, number of pulse trains, etc.) can affect the lesion size. For example, an increased voltage can correspondingly increase the lesion depth.

[0045] As previously explained herein, the system 10 may include ECG electrodes 26 that may be electrically coupled to the generator 14 and configured to measure electrical signals from the heart. The ECG measurements made by the ECG electrodes 26 may be made sequentially or simultaneously with the delivery of a pulse train from the plurality of electrodes 110. In an example configuration, three ECG electrodes 26 are adhered to a surface of the patient and further coupled to the generator 14. The generator 14 may be configured to process the measured Einthoven signal and correlate it to a determination of when to deliver a pulse, as explained in more detail below. For example, the generator 14 may use predetermined measured patient parameters (e.g., a pulse train associated with the QRS complex (see Figure 3 The generator 14 may be programmed with timing and amplitude parameters associated with the graph 330 of FIG. 330 to control the timing of delivering PFA energy to a treatment site of the patient's heart, as explained in more detail below. When at least one of the predetermined measured patient parameters is met, the generator 14 may initiate delivery of pulses for a predetermined period of time.

[0046] The pulsed field of energy can be delivered in a bipolar manner between odd electrodes and even electrodes with monophasic or biphasic pulses. In the context of cardiac tissue ablation, the application of bipolar biphasic electrical pulses can produce beneficial results, such as well-controlled size / shape of the electric field and less neuromuscular stimulation. For biphasic electroporation pulses, the pulse direction to complete a cycle alternates within a few microseconds. As a result, cells to which biphasic electrical pulses are applied experience alternation of electric field bias. Changing the direction of the bias reduces prolonged post-ablation depolarization and / or ion charging. As a result, the risk of prolonged muscle excitation (e.g., bone and heart cells) and post-shock fibrillation of heart cells can be reduced. Additional details of example pulses / pulse trains that can be used during PFA are explained in U.S. Patent No. 10,531,914, which is incorporated by reference.

[0047] In some examples, the generator 14 controls the timing of PFA energy delivery via one or more electrodes 110 to a treatment site (e.g., a specific region of the heart) based on the cardiac cycle to control (and increase or maximize) the lesion depth and transmurality achieved by PFA. Specifically, PFA energy may be delivered to corresponding specific regions of the heart during diastole (and particularly during the end-diastolic period) during a certain point in the cardiac cycle, where PFA energy is delivered (via electrodes 110 on catheter 112) to increase or maximize lesion depth and / or thereby achieve transmural lesions. For example, in some examples, the generator 14 may perform Figure 5 500 is provided to control the delivery of PFA energy to a treatment area by controlling the generation of a waveform / signal provided to the electrode 110 so that the electrode 110 provides / delivers PFA energy. In some examples, the diastole period of a particular region of the heart is the phase of the heartbeat when the myocardium relaxes and allows the chambers of the heart to fill with blood (e.g., see Figure 3 In some examples, the end-diastolic period is the period at the end of the diastolic period. For example, the end-diastolic period may be just before the peak of the electrical stimulation wave (e.g., R-wave) that initiates contraction of a particular region of the heart (i.e., the systolic period) occurs (e.g., see Figure 3 The ventricular end-diastolic period 335). The systole of the heart is the contraction phase of the heartbeat as the heart muscle contracts and pumps blood from the chambers of the heart into the arteries. In some examples, the end-diastolic period may occur during a range of 90% to 99.99% (or 80% to 99.99% or 95% to 99.99%, etc.) of the diastolic period.

[0048] Figure 2 1 is a block diagram of a generator 14 of an ablation system 10 according to one example. In the example shown, the generator 14 includes an electronic processor 205 (e.g., a microprocessor or another electronic device). The electronic processor 205 can be electrically connected to a memory 210 and can include input and output interfaces to communicate with other devices of the system 10 (e.g., such as Figure 2 The remote controller 15 shown in FIG. 1 is coupled to the catheter electrode distribution system 13 ).

[0049] The memory 210 may include a read-only memory (ROM), a random access memory (RAM), other non-transitory computer-readable media, or a combination thereof. The electronic processor 205 is configured to receive instructions and data from the memory 210, and to execute, among other things, these instructions. In particular, the electronic processor 205 executes the instructions or algorithms stored in the memory 210 to provide automated operations and execution for the features, sequences, calculations, or procedures described herein.

[0050] In some aspects, the generator 14 may include a Figure 2 205. For example, in some aspects, the generator 14 includes one or more additional electronic processors that can perform specific functions and can be communicatively coupled to each other and / or to the electronic processor 205. As another example, in addition to or in lieu of the remote controller 15, the generator 14 can include a display and / or an integrated user input device.

[0051] Other devices of the system 10 may include similar components as the generator 14. For example, the catheter electrode distribution system 13, the remote controller 15, and / or the medical device 12 may each include an electronic processor and memory similar to those previously described herein with respect to the generator 14. In some aspects, these other devices 12, 13, 15 may additionally or alternatively have other components that allow each device 12, 13, 15 to perform its respective functionality as described herein.

[0052] In some instances, the electronic processor 205 of the generator 14 controls the timing of PFA energy delivery via one or more electrodes 110 to a treatment site (e.g., a specific region of the heart) based on the cardiac cycle to control (and increase or maximize) the lesion depth and transmurality achieved by PFA. Specifically, PFA energy may be delivered to corresponding specific regions of the heart during diastole (and particularly during the end-diastolic period) during a certain point in the cardiac cycle, where PFA energy is delivered (via the electrodes 110 on the catheter 112) to increase or maximize lesion depth and / or thereby achieve transmural lesions. For example, in some instances, the electronic processor 205 may execute Figure 5 The method 500 shown in FIG. 5 is to control the delivery of PFA energy to a treatment area by controlling the generation of a waveform / signal provided to the electrode 110 so that the electrode 110 provides / delivers the PFA energy.

[0053] Additionally or alternatively, in some instances, the electronic processor 205 can control the delivery of PFA energy to the treatment region such that PFA energy is delivered at times when the cardiomyocytes in the treatment region are aligned / oriented in a manner that allows for a higher level of ablation (e.g., more effective ablation) than other arrangements / orientations of the cardiomyocytes. For example, torsional anisotropy may exist in the ventricles or other treatment regions such that the alignment / orientation of the cardiomyocytes changes during the heartbeat. Based on certain alignments / orientations of the cardiomyocytes in the treatment region during different periods of the heartbeat (e.g., as determined by monitoring an individual patient, or as determined generally by studying and monitoring many patients), the electronic processor 205 can control the delivery of PFA energy to the treatment region when the cardiomyocytes in the treatment region are aligned / oriented in a manner that allows for a higher level of ablation than other arrangements / orientations of the cardiomyocytes (e.g., PFA energy delivered when many cardiomyocytes are aligned in the same or similar orientation). Additional information regarding how cellular orientation of a treatment region can affect ablation of a treatment region using some types of PFA energy is disclosed in U.S. patent application Ser. No. 18 / 295,416, filed on April 4, 2023, which is incorporated by reference.

[0054] Figure 3 A plurality of graphs are shown of different known measurements and characteristics of an example heart throughout an example known cardiac cycle (ie, heartbeat). For example, Figure 3 An example QRS complex in a graph 305 of an electrocardiogram (ECG) is shown. The QRS complex includes an R wave 310, which indicates the depolarization of the main mass of the ventricles of the heart to cause the ventricles to contract, forcing blood out of the heart. Figure 3 Also marked in the diagram 305 are ventricular contraction periods 315 and ventricular relaxation periods 320. Contraction periods 315 may indicate the phase of the cardiac cycle when the ventricular myocardium contracts to pump blood from the chambers of the heart into the arteries. Diastole periods 320 may indicate the phase of the cardiac cycle when the ventricular myocardium relaxes and allows the chambers of the heart to fill with blood. The ECG diagram 305 includes markings for other well-known wave types of the cardiac cycle (e.g., P wave 345, T wave, Q wave 355, and S wave).

[0055] In other charts, Figure 3 Also included is a graph 325 of ventricular volume during a cardiac cycle and a graph 330 of ventricular wall thickness (i.e., myocardial thickness) during a cardiac cycle. Graph 330 specifically indicates left ventricular wall thickness. Figure 3As shown, graphs 325 and 330 are approximately negatively correlated with each other at many points in the cardiac cycle. For example, just before and during the occurrence of the R-wave 310 that transitions the heart's ventricles from the diastolic period 320 to the systolic period 315, the ventricle volume is at a maximum and the ventricle wall thickness is at a minimum. Conversely, after blood is forced out of the heart and as the heart's ventricles transition from the systolic period 315 back to the diastolic period 320 to begin to refill with blood, the ventricle volume is at a minimum and the ventricle wall thickness is at a maximum.

[0056] Figure 3 A plurality of graphs corresponding to one of the example scenarios described herein are shown when the electrode 110 is located on the left ventricle of the heart to deliver PFA to the left ventricle. However, as indicated herein, the electrode 110 may be placed at other areas of the heart to deliver PFA, such as at one of the atria. The properties of the atria of the heart (e.g., volume, wall thickness, etc.) may vary differently than those same properties of the ventricles. Figure 3 Graphs corresponding to the characteristics of the ventricles are primarily shown. However, when electrodes 110 are used to deliver PFA to other areas of the heart, values ​​of the same characteristics may be determined and / or estimated for the example heart throughout the example known cardiac cycle. For example, in the case where electrodes 110 are used to deliver PFA to the atria, the characteristics of the atria are used to control the timing of PFA delivery rather than using the characteristics of the ventricles. Thus, when electrodes 110 are used to deliver PFA to other areas of the heart, such as the atria, Figure 3 The systolic period 315 and the diastolic period 320 marked in FIG. 3 may be different sizes and / or may be shifted to be in different periods of the cardiac cycle because other areas of the heart have different systolic and diastolic periods than the ventricles. Figure 3 A graph of atrial wall thickness is not included, but such a graph (and / or data corresponding thereto) may be referenced / used by electronic processor 205 in the event that electrode 110 is used to deliver PFA to the atrium.

[0057] As previously described, the electric field and the lesions produced by the electric field during pulsed field ablation (PFA) can depend on many factors. Given the high voltages / currents applied during PFA, there are concerns about potentially producing arrhythmias. Accordingly, some PFA systems are R-wave gated so that these systems deliver pulses during the ventricular systolic period 315 (i.e., during the maximum contraction of the ventricular myocardium). In other words, in existing systems, PFA energy is delivered during the period immediately following the detection of the R-wave 310 in the patient's cardiac cycle (e.g., during the early portion of the ventricular systolic period 315), which is indicative of depolarization of the major mass of the heart's ventricles.

[0058] However, delivering PFA energy during the ventricular contraction period 315 immediately after the R-wave 310 is detected is not effective in maximizing the depth of injury. In fact, especially in the ventricles, the thickness of the myocardium is at a high level (often at its maximum) during contraction (i.e., the period immediately after the R-wave 310 is detected). For example, Figure 3 The graph 330 of indicates that the ventricular wall thickness is high (i.e., at or near its maximum value) at the end of the ventricular systole period 315 when the ventricular myocardium has just contracted and at the beginning of the ventricular diastole period 320 before the myocardium has fully relaxed to allow blood to enter the heart. Additionally, Figure 3 The graph 330 of indicates that for nearly all of the contraction periods 315, the ventricular wall thickness is approximately 50% or greater of its maximum thickness. Thus, delivering PFA energy to the ventricle during the ventricular contraction period 315 results in less than a maximum penetration depth into the myocardium (and, in some instances, results in a failure to achieve a desired lesion or transmural lesion depth) compared to delivering PFA energy to the ventricle during other periods of the cardiac cycle when the ventricular wall thickness is less (i.e., thinner). Similar issues exist when PFA energy is delivered to other areas of the heart (e.g., one of the atria), although the timing of atrial contraction and atrial relaxation is different from the timing of ventricular contraction and ventricular relaxation. Thus, in some instances, PFA energy may be delivered to cardiac tissue at a suboptimal time that does not maximize lesion depth.

[0059] To address the potential timing issues discussed above, a gated PFA train may be delivered during a diastolic period of the cardiac cycle (e.g., ventricular diastolic period 320). Figure 3 As shown in the graph 330 of FIG. 3 , during ventricular diastole (and particularly during the end of the ventricular diastole period 320, just before the peak of the R wave 310 at the end-diastole period 335), the ventricular myocardium relaxes and the ventricular wall thickness is thinner than during ventricular contraction. Figure 3 As indicated in the graph 330 of , the ventricular wall thickness is at a minimum during the end-diastolic period 335 of the ventricle just prior to the peak of the R-wave 310 that initiates isometric contraction of the ventricle. Thus, delivering PFA energy to the ventricle during ventricular diastole of the cardiac cycle (and particularly during the end-diastolic period 335 of the ventricle) results in increased penetration into the ventricular myocardium (i.e., increased lesion depth). In a similar manner, in the case of providing PFA energy to one of the atria, the delivery of PFA energy can be timed according to atrial diastole or end-diastole. For example, the delivery of PFA energy can be timed to immediately prior to atrial contraction (i.e., immediately prior to the P-wave) to optimize transmural lesion generation in the atria.

[0060] For example, Figure 4A and Figure 4B A simplified diagram showing the same electric field applied to different thicknesses of myocardium (eg, at different time periods in the cardiac cycle). Figure 4C and Figure 4D Shown in Figure 4A and Figure 4B Simplified diagram of example damage depths achieved with the same electric field for the corresponding cases of Figure 4A In Figure 4B As shown, the myocardium 405 during contraction (e.g., ventricular contraction 315) has a first thickness 410 that is greater than a second thickness 415 that the myocardium has during diastole (e.g., ventricular diastole 320) (and particularly during the end-diastolic period 335 of the ventricular diastole). Figure 4A and Figure 4B In each of the embodiments, the same electric field 420 is applied to the myocardium 405. Figure 4A , the electric field 420 is non-transmural because the electric field 420 does not penetrate the entire first thickness 410 of the myocardium 405. Figure 4C As shown, the corresponding depth (i.e., lesion depth / size) of the lesion 425 produced by the electric field 420 is non-transmural (e.g., suboptimal). Figure 4B In the embodiment of the present invention, when the electric field 420 penetrates the entire second thickness 415 of the myocardium 405, the electric field 420 is transmural. Figure 4D As shown, the corresponding depth (ie, lesion depth / size) of the lesion 430 created by the electric field 420 is transmural (ie, present or occurs across the entire wall of the myocardium 405).

[0061] The creation of deeper lesions during atrial or ventricular ablation may be clinically relevant. To date, there is little evidence that the biphasic high-frequency pulse waveforms used during PFA are proarrhythmic, particularly when used in Figure 3 Accordingly, delivering PFA energy to the atrium or ventricle during corresponding atrial or ventricular diastole (and particularly during corresponding end-diastolic periods, such as during ventricular end-diastole 335 when PFA energy is being delivered to the ventricle) solves the above-mentioned technical problems by: (i) increasing the depth of injury compared to delivering PFA energy during contraction (e.g., when PFA is delivered to the ventricle immediately after detecting an R-wave 310 indicating ventricular contraction 315); and (ii) not significantly increasing or at all increasing the chances of producing arrhythmias.

[0062] Figure 5 A flow chart of a method 500 executed by the electronic processor of the generator 14 (possibly in conjunction with other devices in the system 100) to control the delivery of PFA energy to the heart (cardiac tissue) of a patient is shown. Figure 5 A particular order of processing steps is indicated in the drawings as an example, but the timing and sequencing of such steps may be varied where appropriate without negating the purposes and advantages of the examples set forth in detail throughout the remainder of the disclosure.

[0063] At box 505, the electrical signal of the patient's heart is monitored. The electrical signal indicates that the heart is beating. For example, an electrocardiogram (ECG) of the patient's heart is determined by the electronic processor 205 of the generator 14. In some aspects, the ECG may be determined by another electronic processor of another device. The ECG is determined based on the electrical signal received from one or more electrodes. The electrodes that provide the electrical signal that allows the ECG to be determined may include one or more electrodes in the electrode 110, one or more ECG electrodes in the ECG electrode 26, or a combination thereof. In some aspects, the first electrode 110 that delivers PFA energy to the treatment site of the heart can also be used to monitor the electrical signal (e.g., ECG) of the heart. For example, a unipolar signal can be measured from an indwelling PFA catheter with an electrode 110, and the PFA energy can be delivered from the same electrode 110. As another example, a bipolar signal from an indwelling PFA catheter can be measured from two electrodes 110, and the PFA energy can be delivered in a bipolar manner from the two electrodes 110. In some aspects, the above two examples can be mixed and matched. Specifically, a unipolar signal can be measured by an indwelling catheter when bipolar PFA energy is delivered to the treatment site, or vice versa. In some aspects, a second electrode (e.g., ECG electrode 26, an electrode on a separate indwelling catheter such as a coronary sinus catheter, etc.) that is separated from electrode 110 and is not used to deliver PFA energy to the treatment site can be used to monitor the heart's electrical signals for generating ECG. For example, a separate indwelling coronary sinus catheter can be used to simultaneously measure both atrial and ventricular signals. In some instances, the electronic processor 205 receives additional or alternative information to monitor the patient's cardiac cycle and associated timing. For example, the electronic processor 205 can receive intracardiac electrogram (EGM) information and / or other information from one or more other electrodes and / or devices / sensors.

[0064] At block 510, the electronic processor 205 of the generator 14 determines an end-diastolic period (e.g., end-diastolic period 335) at the end of a diastolic period (e.g., ventricular diastolic period 320) during which diastolic period has occurred during a previous cardiac cycle, based on the electrical signal (e.g., ECG) monitored at block 505. Diastolic period of the heart (e.g., ventricular diastolic period) In some aspects, diastolic period of the heart may refer to diastolic period of any of different specific parts of the heart (e.g., left ventricle, right ventricle, left atrium, right atrium, a specific part of a previous general part of the heart, such as the apex, base, ventricular septum, atrial septum, etc.). In some aspects, the specific diastolic period and end-diastolic period of the heart determined at block 510 may be determined differently based on the location of the heart as a treatment site intended to receive PFA energy. For example, in the case where PFA energy is provided to one of the atria rather than the ventricles, the delivery of the PFA energy can be timed according to atrial diastole or end-diastole. For example, when PFA energy is being delivered to the ventricles, the delivery of the PFA energy can be timed to be immediately prior to atrial contraction (i.e., immediately prior to the P wave) rather than immediately prior to the R wave.

[0065] Figure 3 The example end-diastolic period 335 shown is a period during which the left ventricle wall thickness is low or at a minimum just before the R-wave 310 occurs to initiate isometric contraction of the left ventricle. However, in some aspects, the end-diastolic period is alternatively a different period during which the thickness of the wall of another portion of the heart (e.g., the right ventricle, one of the atria, a specific portion of one of the previous general portions of the heart such as the apex, base, ventricular septum, atrial septum, etc.) is at a minimum. Thus, Figure 3 The end-diastolic period 335 shown in FIG. 1 is an example and may be sized and / or shifted differently within the cardiac cycle depending on the portion of the heart that is the treatment site to be ablated by receiving PFA energy. For example, based on known properties of the heart, a graph of wall thickness of different portions of the heart may be plotted with respect to FIG. Figure 3 The graph 330 of left ventricular wall thickness shown is different. These graphs (not shown) of wall thickness of different parts of the heart throughout the cardiac cycle (e.g., graphs of atrial wall thickness) can be used in a similar manner as using graph 330, and similar calculations as described below with respect to end-diastolic period 335 and diastolic period 320 can be performed to determine other end-diastolic periods and diastolic periods for different parts of the heart. These other end-diastolic periods may be useful when the treatment site to be delivered PFA energy is other than the left ventricle (or a specific part of the left ventricle, such as the apex or base).

[0066] In some aspects, the electronic processor 205 is configured to determine the end-diastolic period 335 by determining a first time interval between occurrences of a first wave and a second wave included in an electrical signal (e.g., ECG) of one or more previous cardiac cycles. In some aspects, the first wave and the second wave are consecutive occurrences of the same first type of wave included in the electrical signal. In other words, in some aspects, the electronic processor 205 is configured to determine a first time interval between consecutive occurrences of a first type of wave included in the electrical signal.

[0067] For example, the first type of wave may be an R wave 310, and the first time interval may be Figure 3 340 between the peaks of consecutive R waves 310 of consecutive cardiac cycles shown. As another example, the first type of wave may be a P wave 345 and the first time interval may be a PP interval. As an example where the first wave and the second wave are not the same type of wave, the first wave may be a P wave 345 and the second wave may be an R wave 310. In this example, the first time interval may be as follows: Figure 3 PR interval 350 between the peak of the P wave 345 and the next R wave 310 shown. Other types of waves and intervals may also be used in some aspects. In some aspects, the first wave, the second wave, and / or the first type of wave are selected based on the location of the heart intended to receive PFA energy. For example, the electronic processor 205 can be programmed to detect different waves in the ECG and / or different time intervals between waves in the ECG based on the location of the heart intended to receive PFA energy. As a more specific example, while it may be useful to time the delivery of PFA energy to immediately before the peak of the R wave 310 when the PFA energy is delivered to one of the ventricles as explained below, it may be useful to time the delivery of PFA energy to immediately before the peak of the P wave 345 when the PFA energy is delivered to one of the atria using similar techniques. Therefore, for atrial applications, instead of determining the RR interval 340 or the PR interval 350, the electronic processor 205 can determine the PP interval or the RP interval.

[0068] In some aspects, the electronic processor 205 is configured to determine the first time interval by determining an average of a plurality of measured time values ​​(e.g., from a plurality of cardiac cycles) corresponding to the first time interval. Although the time intervals in the cardiac ECG (e.g., RR intervals 340, PR intervals 350, etc.) may maintain some consistency between cardiac cycles, there may be some variability in these time intervals when comparing different cardiac cycles. Since the method 500 is designed to deliver PFA energy to the treatment site of the heart at very specific times during the cardiac cycle, in some aspects, the consistency of the measured time values ​​corresponding to the time intervals in the cardiac cycle is determined by the electronic processor 205. For example, the electronic processor 205 may be configured to determine the time value of each of the plurality of first time intervals included in the electrical signal within an evaluation period including a plurality of cardiac cycles before delivering PFA energy in a later cardiac cycle. The electronic processor 205 may also be configured to determine a variation between the time values ​​and compare the variation to a variation threshold. For example, the variation threshold may be a standard deviation value or a difference between the highest and lowest measured time values ​​included in the plurality of first time intervals. In response to determining that the change is below a change threshold, the electronic processor 205 can be configured to establish the first time interval by determining an average of the time values ​​of the plurality of first time intervals. In some aspects, determining that the change is below the change threshold indicates that the time values ​​of the plurality of first time intervals are sufficiently consistent to be accurately used to time the delivery of PFA energy. In response to determining that the change is greater than or equal to the change threshold, the electronic processor 205 can be configured to continue monitoring the electrical signal (at block 505) and / or can provide a notification to a user.

[0069] Because consistency of the time values ​​of the plurality of first time intervals affects the accuracy of the timing of the delivery of PFA energy, in some aspects, the heart may be artificially paced by one or more of electrodes 110 or by a separate pacing device. In some aspects, an evaluation period for measuring the plurality of first time intervals prior to delivering PFA energy may be configured to be longer when the patient's heart is not artificially paced than when the patient's heart is artificially paced. For example, when the heart is artificially paced, the evaluation period for attempting to ensure consistent time intervals within the cardiac cycle may be lower than when the heart is not artificially paced because the cardiac cycle of an artificially paced heart will likely be more consistent than the cardiac cycle of a heart that is not artificially paced.

[0070] In some aspects, the electronic processor 205 determines a time range (e.g., an average time range) of the end-diastolic period 335 during one or more previous cardiac cycles based on an average of a plurality of first time intervals determined as previously described herein. For example, the electronic processor 205 can be configured to determine that the end-diastolic period 335 occurs during a range of 90% to 99% (or 80% to 99%, or 70% to 99%, or 60% to 99%, or 50% to 99%, or 90% to 95%, or 80% to 95%) of the first time intervals (e.g., RR intervals 340) between successive occurrences of a first type of wave (e.g., R-wave 310) following an instance of the first type of wave (e.g., R-wave 310). Continuing with this example, if the average of the first time intervals is 1000 milliseconds, the end-diastolic period 335 can be determined to be 900 milliseconds to 990 milliseconds. As another example, the electronic processor 205 determines that the end-diastolic period 335 occurs during a range of 50% to 99% (or 30% to 99%, or 1% to 99%) of a first time interval (e.g., the PR interval 350) between an occurrence of a first wave (e.g., the P wave 345) and an occurrence of a second wave (the R wave 310) following an instance of the first wave (e.g., the P wave 345). Figure 3 As shown in and by way of example above, the electronic processor 205 can be configured to determine the end-diastolic period 335 as the period immediately preceding another instance of the first wave or wave of the first type (e.g., the next predicted instance) based on monitoring of previous cardiac cycles. Thus, during at least a portion of the end-diastolic period 335, for example, just before the left ventricle begins to contract to force blood out of the left ventricle, the myocardium / heart wall thickness is expected to be low or at a level such as Figure 3 Minimum value shown.

[0071] At box 515, the electronic processor 205 is configured to determine that another cardiac cycle has begun based on the electrical signal (e.g., ECG). In some instances, the electronic processor 205 is configured to determine that each cardiac cycle has begun in response to determining another instance of the occurrence of a first wave or a first type of wave in the electrical signal. For example, the start of a cardiac cycle can be determined by the electronic processor 205 sensing an R wave 310, a P wave 345, or another type of wave. In response to detecting another instance of the same type of wave, the electronic processor 205 can determine that the previous cardiac cycle has ended and a new cardiac cycle has begun. For example, the electronic processor 205 can determine the PR interval 350 (at box 510) and can use each detection of the P wave 345 to indicate that a new (i.e., another) cardiac cycle has begun, even though the P wave 345 can be considered to occur in the middle of a cardiac cycle in some scenarios. As another example, the electronic processor 205 can determine the RR interval 340 (at box 510) and can use each detection of the R wave 310 to indicate that a new (i.e., another) cardiac cycle has begun. In some examples, the start point, the end point, or both of the start and end points of an interval described herein (e.g., RR interval 340, PR interval 350, etc.) can be determined by the respective waves comprising the interval being at their peaks (e.g., see Figure 3 The start point, end point, or both of the start and end points of an interval described herein may be defined by the time when the corresponding waves constituting the interval just begin to form (e.g., see Figure 3 The time is defined as the start of the PR interval 350 marked in FIG.

[0072] At block 520, the electronic processor 205 causes one or more of the electrodes 110 to deliver pulsed field ablation (PFA) energy to the heart during at least a portion of the time that the end-diastolic period 335 of another (i.e., newly detected and current) cardiac cycle is expected to occur. For example, the electronic processor 205 controls the generation of the waveform / signal provided to the electrodes 110 so that the electrodes 110 provide / deliver PFA energy to the heart during at least a portion of the time that the end-diastolic period 335 of another (i.e., newly detected and current) cardiac cycle is expected to occur. In some instances, the end-diastolic period 335 of another cardiac cycle may be expected to occur at approximately the same time as the end-diastolic period 335 occurred in one or more previous cardiac cycles. In other words, the electronic processor 205 may be configured to determine when the end-diastolic period 335 of another cardiac cycle is expected to occur based on when the end-diastolic period 335 occurred during one or more previous cardiac cycles. In some examples, PFA energy may be delivered at any time point during the end-diastolic period 335 or within any time period during the end-diastolic period 335 (e.g., during the period when the end-diastolic period 335 is expected to occur). In some examples, PFA energy may be delivered as close to the end of the end-diastolic period 335 as possible (e.g., as close as possible to the estimated time of the next R-wave 310) in an attempt to ensure that the myocardium / heart wall thickness is as low or at a minimum as possible. In some examples, PFA energy may be delivered to the heart during at least a portion of the time when the end-diastolic period 335 of the current cardiac cycle is expected to occur based on a first time interval determined (at block 510) based on a previous cardiac cycle. For example, PFA energy is delivered to the heart during at least a portion of the time included in the range of 90% to 99% of the first time interval after another instance of a wave of the first type occurs (or one of the other ranges listed above or similar ranges) because this range corresponds to the period when the end-diastolic period 335 of another / current cardiac cycle is expected to occur. In some examples, PFA energy is delivered during the Q wave 355 and / or during the beginning portion of the R wave 310 before the peak of the R wave 310 is detected (eg, Figure 3 , as indicated by the end-diastolic period 335 shown in FIG.

[0073] As indicated in the above explanation, execution of method 500 allows the electronic processor 205 to control the timing of delivery of PFA energy to a treatment site of the heart such that PFA energy is delivered at a low or minimum myocardium / heart wall thickness at the treatment site without actually / physically measuring the myocardium / heart wall thickness at the treatment site.

[0074] like Figure 5 As indicated in , after performing block 520 , method 500 may continue back to block 505 and may repeat.

[0075] In some examples, an imaging device (e.g., an echocardiogram imaging device, a magnetic resonance imaging (MRI) device, a computed tomography (CT) scanning device, etc.) can be used simultaneously and in combination with monitoring of the heart's electrical signals (e.g., ECG) prior to delivery of PFA energy to determine periods of time during which low or minimal myocardium / heart wall thickness at the treatment site occurs during a beating heart. For example, using images (e.g., ventriculograms) obtained by an imaging device (e.g., a transesophageal echocardiogram device, an intracardiac echocardiogram device, etc.), low or minimal myocardium / heart wall thickness at the treatment site can be determined by the electronic processor 205. The images can be time-stamped so that the electronic processor 205 (which can also monitor the heart's electrical signals) can determine periods during a heartbeat (e.g., the same / similar periods during multiple heartbeats) during which low or minimal myocardium / heart wall thickness at the treatment site occurs. The electronic processor 205 can then determine an end-diastolic period 335 based on the combined imaging / electrical signal information (e.g., during a heartbeat period when the image indicates that the myocardium / heart wall thickness at the treatment site is at a low or minimum value) during which PFA energy is applied for treatment during a later heartbeat. In some examples, the electronic processor 205 can be configured to determine one or more other periods during a heartbeat during which PFA energy can be applied (e.g., due to low or minimum heart wall thickness), as long as such other periods do not conflict with other studies, determinations, etc. regarding when PFA energy can be safely applied.

[0076] Thus, in some instances, the timing of delivering PFA energy to the heart can be determined on a patient-specific basis based on when low or minimal myocardial / heart wall thickness occurs at the treatment site. Such timing can be determined using (i) timing estimates from previous cardiac cycles and / or (ii) thickness measurements based on images taken during previous cardiac cycles.

[0077] The ranges included herein (e.g., percentage ranges of the first time interval) are examples. One or both ends of each of these example ranges may vary, for example, by 1%, 5%, 10%, etc. These example ranges are intended to depict approximate time ranges during which the thickness of the myocardium / heart wall at the treatment site is estimated / expected to be low or at a minimum thickness compared to the thickness of the myocardium / heart wall at other times in the cardiac cycle.

[0078] It should be understood that the various aspects disclosed herein may be combined in combinations different from those specifically presented in the specification and drawings. It should also be understood that, depending on the example, certain actions or events of any of the processes or methods described herein may be performed in a different order, may be added, merged, or omitted entirely (e.g., not all described actions or events may be required to perform these techniques). In addition, although for clarity, certain aspects of the present disclosure are described as being performed by a single module or unit, it should be understood that the techniques of the present disclosure may be performed by a combination of units or modules associated with, for example, a medical device.

[0079] In one or more examples, the described techniques can be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions can be stored as one or more instructions or codes on a computer-readable medium and executed by a hardware-based processing unit. The computer-readable medium may include a non-transitory computer-readable medium that corresponds to a tangible medium, such as a data storage medium (e.g., RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and can be accessed by a computer).

[0080] Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuits. Thus, the term "processor" as used herein may refer to any of the aforementioned structures or any other physical structure suitable for implementing the described techniques. Additionally, these techniques may be fully implemented in one or more circuits or logic elements.

Claims

1. A method for ablating cardiac tissue, the method comprising: monitoring electrical signals from a patient's heart, the electrical signals indicating that the heart is beating; determining, with an electronic processor and based on the electrical signal, an end-diastolic period at the end of a diastolic period in which diastole of the heart had occurred during a previous cardiac cycle; determining, using the electronic processor and based on the electrical signal, that another cardiac cycle has begun; as well as During at least a portion of the time when the end-diastolic period of the another cardiac cycle is expected to occur, electrodes are caused to deliver pulsed field ablation (PFA) energy to the heart using the electronic processor.

2. The method of claim 1 , wherein determining the end-diastolic period comprises: determining, with the electronic processor and based on the electrical signal, a first time interval between occurrences of a first wave and a second wave included in the electrical signal of one or more prior cardiac cycles; wherein determining that another cardiac cycle has begun comprises: determining, using the electronic processor and based on the electrical signal, that another instance of the first wave has occurred in the current cardiac cycle; and Wherein causing the electrode to deliver the PFA energy to the heart comprises: based on the first time interval, using the electronic processor, causing the electrode to deliver the PFA energy to the heart during the at least a portion of the time when the end-diastolic period of the current cardiac cycle is expected to occur.

3. The method of claim 2, wherein the first wave and the second wave are the same type of wave, and wherein the first time interval occurs between successive occurrences of the first type of wave included in the electrical signal. 4 . The method of claim 3 , wherein the first time interval comprises an RR interval and the first type of wave comprises an R wave.

5. The method of claim 3, further comprising selecting a type of wave of the first type based on a location of a treatment site of the heart intended to receive the PFA energy.

6. The method of claim 2, wherein the first wave is a first type of wave and the second wave is a second type of wave different from the first type of wave.

7. The method of claim 6, wherein the first type of wave comprises a P wave and the second type of wave comprises an R wave, and wherein the first time interval comprises a PR interval.

8. The method of claim 6, further comprising selecting the first type of wave, the second type of wave, or both based on a location of a treatment site of the heart intended to receive the PFA energy.

9. The method of claim 2, wherein determining the first time interval comprises: determining a time value for each of a plurality of first time intervals included in the electrical signal during an evaluation period prior to delivering the PFA energy; determining changes between said time values; comparing the change to a change threshold; as well as In response to determining that the change is below the change threshold, the first time interval is established by determining an average of the time values.

10. The method of claim 9, wherein the evaluation period is longer when the heart of the patient is not artificially paced than when the heart of the patient is artificially paced.

11. The method of claim 2 further comprising determining, using the electronic processor, that the end-diastolic period is expected to occur during a time period within a range of 90% to 99% of the first time interval after the occurrence of the other instance of the first type of wave.

12. The method of claim 1, wherein the relaxation of the heart comprises one of left ventricular diastole, right ventricular diastole, left atrial diastole, and right atrial diastole.

13. A method according to claim 1, wherein the end-diastolic period of the other cardiac cycle indicates that: during at least a portion of the time when the end-diastolic period of the other cardiac cycle is expected to occur, the myocardium included in the treatment site of the heart intended to receive the PFA energy has a minimum thickness compared to the thickness of the myocardium throughout the remainder of the other cardiac cycle.

14. A system for ablating cardiac tissue, the system comprising: A generator comprising an electronic processor configured to: monitoring electrical signals from a patient's heart, the electrical signals indicating that the heart is beating; determining an end-diastolic period based on the electrical signal, the end-diastolic period being at the end of a diastolic period in which diastole of the heart had occurred during a previous cardiac cycle; determining, based on the electrical signal, that another cardiac cycle has begun; as well as Electrodes are caused to deliver pulsed field ablation (PFA) energy to the heart during at least a portion of the time when the end-diastolic period of the another cardiac cycle is expected to occur.

15. The system of claim 1, wherein the electronic processor is configured to determine the end-diastolic period by: determining, based on the electrical signal, a first time interval between occurrences of a first wave and a second wave included in the electrical signal of one or more prior cardiac cycles; wherein the electronic processor is configured to determine that another cardiac cycle has begun by: determining based on the electrical signal that another instance of the first wave has occurred in a current cardiac cycle; and Wherein the electronic processor is configured to cause the electrode to deliver the PFA energy to the heart in the following manner: based on the first time interval, the electrode delivers the PFA energy to the heart during at least a portion of the time when the end-diastolic period of the current cardiac cycle is expected to occur.

16. The system of claim 15, wherein the electronic processor is configured to determine that the end-diastolic period is expected to occur during a time period within a range of 90% to 99% of the first time interval after the occurrence of the other instance of the first type of wave.

17. The system of claim 14, wherein the relaxation of the heart comprises one of left ventricular diastole, right ventricular diastole, left atrial diastole, and right atrial diastole.

18. A system according to claim 14, wherein the end-diastolic period of the other cardiac cycle indicates that: during at least a portion of the time when the end-diastolic period of the other cardiac cycle is expected to occur, the myocardium included in the treatment site of the heart intended to receive the PFA energy has a minimum thickness compared to the thickness of the myocardium throughout the remainder of the other cardiac cycle.

19. A method of ablating cardiac tissue, the method comprising: monitoring electrical signals from a patient's heart, the electrical signals indicating that the heart is beating; determining, using an electronic processor and based on the electrical signal, a first time interval between occurrences of a first wave and a second wave included in the electrical signal of one or more prior cardiac cycles; determining, using the electronic processor and based on the electrical signal, that another instance of the first wave has occurred in a current cardiac cycle; as well as The electrodes are caused to deliver pulsed field ablation (PFA) energy to the heart using the electronic processor during at least a portion of the time included in the range of 90% to 99% of the first time interval after the first wave has occurred in the current cardiac cycle.

20. A method according to claim 19, wherein the time included in the range of 90% to 99% of the first time interval after the first wave has appeared indicates that: during at least a portion of the time included in the range of 90% to 99% of the first time interval after the first wave has appeared, the myocardium included in the treatment site of the heart intended to receive the PFA energy has a minimum thickness compared to the thickness of the myocardium throughout the remainder of the current cardiac cycle.

Images