Pulsed field ablation system and leakage protection thereof

Abstract

One aspect provides a pulsed field ablation system that includes a bridge circuit configured to deliver bipolar and dual-phase voltage pulses to a catheter. A leakage fault protection circuit is electrically coupled to the bridge circuit and includes a first comparator. An electronic processor is electrically coupled to the bridge circuit and the leakage fault protection circuit. The electronic processor is configured to determine a first bias threshold to correct a first bias referenced at the first comparator, and to set a first threshold parameter of the first comparator based on the first bias threshold and a leakage current parameter of the pulsed field ablation system. The electronic processor is further configured to determine a leakage fault when a detection parameter corresponding to the leakage fault satisfies the first threshold parameter at the first comparator.

Description

Technical Field

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 387,466, filed on December 14, 2022, the entire content of which is incorporated herein by reference. Technical Field

[0003] The present technology generally relates to leakage fault protection for a pulsed field ablation system. Background Art

[0004] Pulsed field ablation delivers rapid, bipolar, and biphasic high voltage pulse sequences to effect irreversible electroporation of tissue. Pulsed field ablation is used to treat arrhythmias and atrial fibrillation, among others. Pulsed field ablation can also be used as an oncological treatment for cancer. Summary of the Invention

[0005] A pulsed field ablation system can be used to deliver rapid, bipolar, and biphasic high voltage direct current (DC) pulse sequences to a patient such that successful irreversible electroporation occurs. A catheter is used to deliver the high voltage pulses to the patient. The pulsed field ablation system uses a large amount of power and energy. A number of transistor switches (e.g., insulated gate bipolar transistors (IGBTs), field effect transistors (FETs), etc.) are used to control pulse delivery. A leakage fault in the pulsed field ablation system (e.g., a transistor switch) can cause unwanted or non-therapeutic current to be delivered to the patient.

[0006] Accordingly, leakage fault protection is needed in a pulsed field ablation system.

[0007] The technology described herein generally relates to leakage fault protection circuits and methods for a pulsed field ablation system. The leakage fault protection circuits and methods help reduce unwanted or non-therapeutic current delivered to the patient. Additionally, the leakage fault protection circuits and methods account for component biasing in the leakage fault protection circuit to help avoid false detection of leakage faults.

[0008] One aspect provides a pulsed field ablation system that includes: a bridge circuit configured to deliver bipolar and biphasic voltage pulses to a catheter; a leakage fault protection circuit electrically coupled to the bridge circuit and including a first comparator; and an electronic processor electrically coupled to the bridge circuit and the leakage fault protection circuit. The electronic processor is configured to determine a first bias threshold to correct a first bias referenced at the first comparator, and set a first threshold parameter of the first comparator based on the first bias threshold and a leakage current parameter of the pulsed field ablation system. The electronic processor is further configured to determine the leakage fault when detection parameters corresponding to the leakage fault satisfy the first threshold parameter at the first comparator.

[0009] On the other hand, a method for leakage fault protection in a pulsed field ablation system is provided. The pulsed field ablation system includes a bridging circuit configured to deliver bipolar and biphasic voltage pulses to a catheter and a leakage fault protection circuit electrically coupled to the bridging circuit and including a first comparator. The method includes using an electronic processor to determine a first bias threshold to calibrate a first bias referenced at the first comparator, and using the electronic processor to set a first threshold parameter of the first comparator based on the first bias threshold and a leakage current parameter of the pulsed field ablation system. The method further includes using the first comparator to determine the leakage fault when a detection parameter corresponding to the leakage fault satisfies the first threshold parameter at the first comparator.

[0010] Various embodiments, examples, aspects, and features are set forth in the following description and the drawings. Other embodiments, examples, aspects, features, objects, and advantages of the techniques described in this disclosure will be apparent from the specification, the drawings, and the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Like reference numerals in the drawings denote identical or functionally similar elements in the various views. The drawings are incorporated into the specification and form a part of the specification, and are used to further illustrate various embodiments, examples, aspects, and features including the claimed subject matter, and to explain the various principles and advantages of those embodiments, examples, aspects, and features.

[0012] Figure 1 is a simplified block diagram illustrating a pulsed field ablation system according to some examples.

[0013] Figure 2 illustrates an example of a voltage pulse delivered by a pulsed field ablation system according to some examples Figure 1 of.

[0014] Figure 3 is an illustration according to some examples of Figure 1 a simplified schematic diagram of a bridging circuit of a pulsed field ablation system.

[0015] Figure 4 is an illustration according to some examples of Figure 1 a simplified block diagram of a leakage fault protection circuit of a pulsed field ablation system.

[0016] Figure 5 is a flowchart of a method for determining a bias of a leakage fault protection circuit for Figure 4 according to some examples.

[0017] Figure 6 is according to some examples for Figure 1Flowchart of a method for detecting leakage faults in a pulsed field ablation system.

[0018] Figure 7 is a flowchart of a method for leakage fault protection in a pulsed field ablation system for Figure 1 according to some examples.

[0019] Those skilled in the art will understand that the elements in the drawings are illustrated for simplicity and clarity and are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be enlarged relative to other elements to help improve the understanding of the examples of the present invention.

[0020] Device and method components have been represented by conventional symbols in the drawings where appropriate, so as to show only those specific details relevant to the understanding of the embodiments, examples, aspects, and features, without confusing the disclosure with details that are readily apparent to those of ordinary skill in the art and that have the benefits described herein. Detailed Description

[0021] Before explaining any embodiments, examples, aspects, and features in detail, it should be understood that those embodiments, examples, aspects, and features are not limited in their application to the construction details and component arrangements set forth in the following description or illustrated in the following drawings. Other embodiments, examples, aspects, and features are possible and can be practiced or carried out in various ways.

[0022] In addition, it should be understood that the wording and terminology used herein are for the purpose of description and should not be regarded as restrictive. The terms "mounted," "connected," and "coupled" are used broadly and encompass direct and indirect mounting, connection, and coupling. The terms "connected" and "coupled" are not limited to physical or mechanical connection or coupling and may include direct or indirect electrical connection or coupling. The electronic communication and notification described herein can be performed using any known or future-developed means, including wired connections, wireless connections, etc.

[0023] For ease of description, some or all of the example systems presented herein are illustrated with a single example of each of their components. Some examples may not describe or illustrate all components of the system. Other embodiments may include more or fewer of each of the illustrated components, may combine some components, or may include additional or alternative components.

[0024] Figure 1 is a simplified block diagram of an example pulsed field ablation system 100. In the example shown, the pulsed field ablation system 100 is used to apply a sequence of fast, bipolar, and biphasic voltage pulses 160 (e.g., as Figure 2as shown) is delivered to the catheter 110 to perform irreversible electroporation of tissue. The pulsed field ablation system 100 includes a bridging circuit 120, a leakage fault protection circuit 130, an electronic processor 140, and a memory 150.

[0025] The catheter 110 is a multi-electrode catheter that includes a plurality of electrodes arranged successively around a closed or semi-closed region. The catheter 110 delivers voltage pulses to tissue within the closed or semi-closed region. In some examples, the catheter 110 may be a disposable catheter 110 that is set up after each use, and a new disposable catheter 110 is connected to the pulsed field ablation system 100 for each different procedure. The bridging circuit 120 is electrically coupled to the catheter 110. The bridging circuit 120 generates voltage pulses and delivers the voltage pulses to the catheter 110. The leakage fault protection circuit 130 is electrically coupled to the bridging circuit 120. The leakage fault protection circuit 130 detects leakage faults within the bridging circuit 120.

[0026] The electronic processor 140 is electrically coupled to the bridging circuit 120 and the leakage fault protection circuit 130 and is configured to control and monitor the bridging circuit 120 and the leakage fault protection circuit 130. In some cases, the electronic processor 140 is implemented as a microprocessor with a separate memory (such as the memory 150). In other embodiments, the electronic processor 140 may be implemented as a microcontroller (with the memory 150 on the same chip). In other embodiments, the electronic processor 140 may be implemented using multiple processors. Additionally, the electronic processor 140 may be partially or fully implemented as, for example, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), an x86 processor, etc., and the memory 150 may be unnecessary or may be modified accordingly. In the illustrated example, the memory 150 includes non-transitory computer-readable memory that stores instructions received and executed by the electronic processor 140 to perform the functionality of the pulsed field ablation system 100 described herein. The memory 150 may include, for example, a program storage area and a data storage area. The program storage area and the data storage area may include a combination of different types of memory, such as read-only memory and random access memory. In some embodiments, the pulsed field ablation system 100 includes one electronic processor 140 and / or multiple electronic processors 140 in a computer cluster arrangement, and one or more of the multiple electronic processors may not be executing the application of the pulsed field ablation system 100, may be executing all of the applications of the pulsed field ablation system application, or may be executing a portion of the applications of the pulsed field ablation system application.

[0027] Figure 3A simplified schematic diagram of the bridge circuit 120 is illustrated. In the illustrated example, the bridge circuit 120 is a full H-bridge circuit. In other examples, the bridge circuit 120 can be an inverter bridge circuit or the like. The full H-bridge circuit is composed of a first transistor switch 210, a second transistor switch 220, a third transistor switch 230, and a fourth transistor switch 240. The transistor switches 210-240 include, for example, insulated gate bipolar transistors (IGBTs), field effect transistors (FETs), etc.

[0028] The power supply 250 supplies high-voltage power to the H-bridge circuit. For the pulsed field ablation system 100, the high-voltage power can be in the range between 300 volts and 2000 volts. The power supply 250 generates a high-voltage potential between a positive power supply node 250A and a negative power supply node 250B (e.g., electrical ground). The power supply 250 can include a high-voltage battery system or an alternating current (AC) power system that is converted to direct current (DC) power.

[0029] The first transistor switch 210 is electrically connected between the positive power supply node 250A and the first bridge output node 260. The second transistor switch 220 is electrically connected between the first bridge output node 260 and the negative power supply node 250B. In one example, the source of the first transistor switch 210 is electrically connected to the drain of the second transistor switch 220 at the first bridge output node 260. The third transistor switch 230 is electrically connected between the positive power supply node 250A and the second bridge output node 270. The fourth transistor switch 240 is electrically connected between the second bridge output node 270 and the negative power supply node 250B. In one example, the source of the third transistor switch 230 is electrically connected to the drain of the fourth transistor switch 240 at the second bridge output node 270.

[0030] The bridge circuit 120 further includes a first patient cathode electrode connector 110A and a second patient cathode electrode connector 110B. The first patient cathode electrode connector 110A and the second patient cathode electrode connector 110B are configured to connect to opposite electrodes (e.g., the positive and negative electrodes respectively) of the catheter 110 (e.g., patient load) to deliver voltage pulses from the bridge circuit 120. The first patient cathode electrode connector 110A and the second patient cathode electrode connector 110B are electrically connected between the first bridge output node 260 and the second bridge output node 270. A first relay 280A is disposed between the first bridge output node 260 and the first patient cathode electrode connector 110A, and a second relay 280B is disposed between the second patient cathode electrode connector 110B and the second bridge output node 270. The first relay 280A and the second relay 280B are controlled by the electronic processor 140 to selectively disconnect and close the circuit path between the first bridge output node 260, the catheter 110, and the second bridge output node 270.

[0031] The bridge circuit 120 also includes a first patient-isolated internal load connector 290A and a second patient-isolated internal load connector 290B. The first patient-isolated internal load connector 290A and the second patient-isolated internal load connector 290B connect the patient-isolated internal load 290 between the first bridge output node 260 and the second bridge output node 270. The patient-isolated internal load 290 is used to detect a leakage fault in the bridge circuit 120. A third relay 280C is disposed between the first bridge output node 260 and the patient-isolated internal load 290, and a fourth relay 280D is disposed between the patient-isolated internal load 290 and the second bridge output node 270. The third relay 280C and the fourth relay 280D are controlled by the electronic processor 140 to selectively open and close the circuit path between the first bridge output node 260, the patient-isolated internal load 290, and the second bridge output node 270.

[0032] A first resistor 300A is electrically coupled between (i) the first bridge output node 260 and (ii) the first relay 280A and the third relay 280C. A second resistor 300B is electrically coupled between (i) the second bridge output node 270 and (ii) the second relay 280B and the fourth relay 280D. A third resistor 300C is electrically coupled between the positive power supply node 250A and the first transistor switch 210. A fourth resistor 300D is electrically coupled between the second transistor switch 220 and the negative power supply node 250B. A fifth resistor 300E is electrically coupled between the positive power supply node 250A and the third transistor switch 230. A sixth resistor 300F is electrically coupled between the fourth transistor switch 240 and the negative power supply node 250B. The resistors 300A - 300F can be used as current detection elements of the leakage fault protection circuit 130, as described in more detail below.

[0033] The electronic processor 140 is used to control the transistor switches 210-240 and the relay 280 to selectively open and close the circuit paths respectively. A gate driver may be included in the bridge circuit 120 to provide drive signals to the transistor switches 210-240. The gate driver provides drive signals to the transistor switches 210-240 based on control signals received from the electronic processor 140. When the transistor switches 210-240 are closed, the transistor switches 210-240 allow current to flow through the transistor switches 210-240 to components connected downstream of the transistor switches 210-240. When the transistor switches 210-240 are open, the transistor switches 210-240 prohibit current from flowing through the transistor switches 210-240 to components connected downstream of the transistor switches 210-240. Similarly, when the relay 280 is closed, the relay 280 allows current to flow through the relay 280 to components connected downstream of the relay 280. When the relay 280 is open, the relay 280 prohibits current from flowing through the relay 280 to components connected downstream of the relay 280.

[0034] The first relay 280A and the second relay 280B are closed to form a circuit path between the first bridge output node 260, the conduit 110, and the second bridge output node 270 for delivering therapeutic current to the conduit 110. When delivering therapeutic current to the conduit 110, the third relay 280C and the fourth relay 280D are open. The electronic processor 140 controls the transistor switches 210-240 to provide sequential bipolar, biphasic high-voltage pulses to the conduit 110. The transistor switches 210-240 may be configured such that the transistor switches 210-240 are normally open. That is, the default state of the transistor switches 210-240 is the open state. The electronic processor 140 closes the first transistor switch 210 and the fourth transistor switch 240, and keeps the second transistor switch 220 and the third transistor switch 230 open to provide therapeutic current to the conduit 110 in a first direction (e.g., the positive direction). The electronic processor 140 closes the second transistor switch 220 and the third transistor switch 230, and keeps the first transistor switch 210 and the fourth transistor switch 240 open to provide therapeutic current to the conduit 110 in a second direction (e.g., the negative direction). The switching between the first direction and the second direction is performed at a high frequency. For example, therapeutic current is provided in each direction for a time of 4 microseconds, with a 5-microsecond gap between each direction. During the 5-microsecond gap, all the transistor switches 210-240 are turned off.

[0035] The transistor switches 210 - 240 are used in the bridge circuit 120 due to their near - ideal switching characteristics. During normal operation, the transistor switches 210 - 240 allow current to flow through, and when closed, there is no voltage drop or a very small voltage drop between the drain and source of the transistor switches 210 - 240. When open, the transistor switches 210 - 240 do not allow current or allow a negligible amount of current to flow through the drain and source of the transistor switches 210 - 240. However, even when the transistor switches 210 - 240 are open, the transistor switches 210 - 240 may sometimes fail and allow leakage current to flow through the transistor switches 210 - 240. This leakage current may cause undesired damage to patient tissue.

[0036] The leakage - fault protection circuit 130 can be used during the initialization of the pulsed - field ablation system 100 to detect leakage faults. Figure 4 A simplified schematic diagram of the leakage - fault protection circuit 130 is illustrated. The leakage - fault protection circuit 130 can be connected across any one or more of the resistors 300 (e.g., current - sensing elements). In the illustrated example, the leakage - fault protection circuit 130 includes measurement resistors 300_1 and 300_2 connected in series. The measurement resistors 300_1 and 300_2 represent any one of the resistors 300. A differential amplifier 310 is connected across the measurement resistors 300_1 and 300_2 such that the first ends of the measurement resistors 300_1 and 300_2 are connected to the non - inverting input terminal 310A of the differential amplifier 310, and the second ends of the measurement resistors 300_1 and 300_2 are connected to the inverting input terminal 310B of the differential amplifier 310. Resistors 320A - 320D are connected between the measurement resistors 300_1 and 300_2, the input terminals 310A - 310B of the differential amplifier 310, and the output terminal 310C of the differential amplifier 310 to provide a large voltage gain. The resistors 320A - 320D can be selected to sufficiently amplify the minimum leakage current (e.g., 10 micro - amperes) to be detected in the pulsed - field ablation system 100.

[0037] The output terminal 310C of the differential amplifier 310 is electrically connected to the non - inverting input terminals of a positive - threshold comparator 330 and a negative - threshold comparator 340. The leakage - fault protection circuit 130 includes a digital - to - analog converter 350 that receives a digital input signal 350A from the electronic processor 140 and provides a threshold parameter 350B to the inverting input terminals of the positive - threshold comparator 330 and the negative - threshold comparator 340. The outputs of the positive - threshold comparator 330 and the negative - threshold comparator 340 are monitored by the electronic processor 140.

[0038] The positive threshold comparator 330 is used to detect the leakage current in the positive direction. For example, when the leakage current flows from the first ends of the measuring resistors 300_1 and 300_2 to the second ends. The negative threshold comparator 340 is used to detect the leakage current in the negative direction. For example, when the leakage current flows from the second ends of the measuring resistors 300_1 and 300_2 to the first ends. When current flows across the measuring resistors 300_1 and 300_2, the voltage drop across the measuring resistors 300_1 and 300_2 is amplified by the differential amplifier 310, and a detection parameter proportional to the voltage drop is provided to the non-inverting inputs of the positive threshold comparator 330 and the negative threshold comparator 340. When the detection parameter at the non-inverting input exceeds the threshold parameter at the inverting input, the output of the positive threshold comparator 330 switches states (e.g., from high to low or from low to high). Similarly, when the detection parameter at the non-inverting input exceeds the threshold parameter at the inverting input, the output of the negative threshold comparator 340 switches states. The electronic processor 140 determines the presence of a leakage fault when it detects a state change in the output of the positive threshold comparator 330 or the output of the negative threshold comparator 340.

[0039] In some examples, the electronic processor 140 controls the digital-to-analog converter 350 to provide separate threshold parameters to the positive threshold comparator 330 and the negative threshold comparator 340 to monitor the directionality of the leakage current. For example, the electronic processor 140 controls the digital-to-analog converter 350 to provide a first threshold parameter to the positive threshold comparator 330 and the negative threshold comparator 340 at a first time, and only monitors the output of the positive threshold comparator 330. The electronic processor 140 then controls the digital-to-analog converter 350 to provide a second threshold parameter to the positive threshold comparator 330 and the negative threshold comparator 340 at a second time, and only monitors the output of the negative threshold comparator 340. The first threshold parameter and the second threshold parameter may have different values to account for the directionality of the leakage current flowing across the measuring resistors 300_1 and 300_2. In some cases, the leakage fault protection circuit 130 may use a single threshold comparator to detect leakage faults in either direction.

[0040] Differential amplifier 310 may have a small voltage bias between its non-inverting input 310A and inverting input 310B. This bias varies from component to component and may be caused by manufacturing variations, temperature, bias dependence on the supply voltage, or mismatches in sub-components. An example maximum bias specified by the manufacturer of differential amplifier 310 is + / -200 microvolts. After large amplifier gain, this bias may compete with the detected leakage current and cause false leakage detection at the positive threshold comparator 330 and / or negative threshold comparator 340. For example, to accurately detect a 10 microampere leakage through a 70 milliohm resistor (e.g., resistor 300) amplified with a differential gain of 800 volts / volt, the positive threshold comparator 330 and negative threshold comparator 340 should be able to detect 600 microvolts. However, a 200 microvolt bias between the non-inverting input 310A and inverting input 310B multiplied by an 800 volts / volt gain will produce 160 millivolts at the non-inverting inputs of the positive threshold comparator 330 and negative threshold comparator 340. Without compensation, the differential amplifier 310 bias may cause false leakage detection at the positive threshold comparator 330 and / or negative threshold comparator 340. Additionally, the bias referenced at each of the positive threshold comparator 330 and negative threshold comparator 340 may vary due to non-linearity of the gain, changes in the output common-mode voltage, and input bias differences between comparators 330 - 340.

[0041] Figure 5 is a flowchart of an example method 400 for determining the bias thresholds referenced at comparators 330 - 340 of the leakage fault protection circuit 130. In the illustrated example, method 400 includes using a digital-to-analog converter 350 to provide a plurality of bias thresholds (at block 410) to comparators 330 - 340 (e.g., a first comparator or a second comparator). The electronic processor 140 controls the digital-to-analog converter 350 to provide the plurality of bias thresholds. The plurality of bias thresholds may be selected based on the maximum bias specified by the manufacturer of differential amplifier 310. Continuing with the example mentioned above, when the maximum bias specified by the manufacturer is + / -200 microvolts, the plurality of bias thresholds may be selected as a number of discrete values between just below -160 millivolts and just above +160 millivolts (e.g., between + / -170 millivolts). In one example, the discrete values may be spaced 10 microvolts apart. The electronic processor 140 may select each of the positive threshold comparator 330 and negative threshold comparator 340 individually for testing. When the positive threshold comparator 330 is selected, the electronic processor 140 controls the digital-to-analog converter 350 to scan the plurality of bias thresholds from the lowest value to the highest value. When the negative threshold comparator 340 is selected, the electronic processor 140 controls the digital-to-analog converter 350 to scan the plurality of bias thresholds from the highest value to the lowest value.

[0042] Method 400 further includes using electronic processor 140 to monitor the outputs of comparators 330-340 for multiple bias thresholds (at block 420). Electronic processor 140 monitors the outputs of the positive threshold comparator 330 and the negative threshold comparator 340. The outputs of the positive threshold comparator 330 and the negative threshold comparator 340 depend on the difference between the inputs of the positive threshold comparator 330 and the negative threshold comparator 340. For example, when the non-inverting input of the positive threshold comparator 330 is below the threshold provided to the positive threshold comparator 330, the output of the positive threshold comparator 330 is low (e.g., -5 volts). When the non-inverting input of the positive threshold comparator 330 is above the threshold provided to the positive threshold comparator 330, the output of the positive threshold comparator 330 is high (e.g., +5 volts).

[0043] Method 400 includes using electronic processor 140 to select a bias threshold (e.g., a first bias threshold or a second bias threshold) from multiple bias thresholds based on the outputs of comparators 330-340 (at block 430). Electronic processor 140 monitors the outputs of the positive threshold comparator 330 and the negative threshold comparator 340 to determine when the outputs switch states between high and low. The threshold at which the output states from the multiple bias thresholds switch between high and low is determined as the bias threshold for comparators 330-340. For example, method 400 is repeated for each of comparators 330-340 to determine the second bias threshold for the second comparator.

[0044] Figure 6 is a flowchart of an example method 500 for leak fault detection in the pulsed field ablation system 100. In the illustrated example, method 500 includes using electronic processor 140 to determine bias thresholds to correct the biases (e.g., a first bias or a second bias) referenced at comparators 330-340 of the leak fault protection circuit 130 (at block 510). Electronic processor 140 can perform method 500 for each of the positive threshold comparator 330 and the negative threshold comparator 340 to determine the first bias threshold and the second bias threshold.

[0045] Method 500 includes setting threshold parameters of comparators 330-340 (at block 520) using electronic processor 140 based on a bias threshold and a leakage current parameter of pulse field ablation system 100. The leakage current parameter is, for example, the maximum leakage current that can be safely permitted in pulse field ablation system 100 or the minimum leakage current to be detected in pulse field ablation system 100. In one example, the leakage current parameter is set by the International Electrotechnical Commission to 10 microamps under normal conditions and to 50 microamps for a single fault condition. The threshold parameter can be determined by adding the bias threshold to the product of the voltage drop across resistor 300 due to the leakage current parameter and the differential gain of leakage fault protection circuit 130. For example, when the bias threshold is 50 millivolts, the leakage current parameter is 10 microamps, the resistance value is 75 milliohms, and the differential gain is 800 volts / volt, the threshold parameter can be set to approximately 50.6 millivolts (= 50 millivolts + (10 microamps × 75 milliohms × 800 volts / volt)).

[0046] In some cases, electronic processor 140 determines the bias threshold in multiple iterations (e.g., a first multiple of iterations). For example, electronic processor 140 can determine the bias threshold in five iterations to compensate for temperature and power supply drift during system startup. In these embodiments, the threshold parameter is set when consecutive bias thresholds converge within, for example, 10 millivolts. When the bias threshold does not converge or cannot be determined in multiple iterations (e.g., a second multiple of iterations), electronic processor 140 can output a fault state. For example, when the bias threshold cannot be determined after twenty iterations, electronic processor 140 can output a fault state. Once the threshold parameters for positive threshold comparator 330 and negative threshold comparator 340 are determined, electronic processor 140 saves the threshold parameters to memory 150 to be called when a leakage test is performed.

[0047] Method 500 includes determining a leak fault (at block 530) using comparators 330-340 when detection parameters corresponding to a leak fault satisfy threshold parameters at comparators 330-340. Once the threshold parameters for the positive threshold comparator 330 and the negative threshold comparator 340 are determined and saved, the electronic processor 140 initiates a leak test. To perform the leak test, the electronic processor 140 closes relays 280C and 280D to direct any leakage current through the patient isolation internal load 290 rather than the catheter 110. The electronic processor 140 enables each of the transistor switches 210-240 one by one during a test time period (e.g., 161 milliseconds each). Specifically, to test one of the transistor switches 210-240, the diagonally opposite transistor switches 210-240 for the patient isolation internal load 290 are turned on. For example, to test for a leak fault in the first transistor switch 210, the electronic processor 140 turns on the fourth transistor switch 240 for 161 milliseconds while turning off the other transistor switches 210-230. The electronic processor 140 monitors the outputs of the positive threshold comparator 330 and the negative threshold comparator 340 to detect a leak fault in either direction. The leak test is repeated for each of the transistor switches 210-240. Table 1 below provides an example of the states of the transistor switches 210-240 for testing each of the transistor switches 210-240.

[0048] Table 1: Transistor Switch States for Leakage Testing

[0049] Test On Off Transistor Switch 210 Transistor Switch 240 Transistor Switches 210, 220, 230 Transistor Switch 220 Transistor Switch 230 Transistor Switches 210, 220, 240 Transistor Switch 230 Transistor Switch 220 Transistor Switches 210, 230, 240 Transistor Switch 240 Transistor Switch 210 Transistor Switches 220, 230, 240

[0050] When a leak fault is detected, the electronic processor 140 may output a fault status that provides an indication of the fault (e.g., turn on an LED, sound an alarm, etc.). In some embodiments, when a leak fault is detected, the electronic processor 140 may prevent or inhibit the application of current through the catheter 110. When no leak fault is detected, the electronic processor 140 may automatically open relays 280C and 280D and close relays 280A and 280B to provide a current path through the catheter 110. The electronic processor 140 then controls the transistor switches 210-240 to apply a treatment current to the catheter 110.

[0051] Figure 7 is a flowchart of an example method 600 for leak protection in the pulsed field ablation system 100. Figure 7The flowchart of FIG. illustrates an overall method 600 that can be executed to perform methods 400 and 500. Method 600 illustrates, for example, a state machine for a pulsed field ablation system 100 for performing leak protection and can be executed by an electronic processor 140. In the illustrated example, method 600 includes initiating a leak test (at block 605). The leak test can be initiated each time the system is started before the pulsed field ablation system is ready to deliver therapeutic current. Initiating the leak test can include resetting previously determined or stored variables (e.g., previously determined threshold parameters or bias thresholds).

[0052] Method 600 also includes charging power supply 250 to prepare the leak system (at block 610). Power supply 250 can be turned on so that power supply 250 is ready to provide operating power to perform the leak test. Method 600 includes finding threshold parameters (at block 615). Method 400 can be executed to find the threshold parameters. Method 600 determines whether the minimum number of iterations of block 615 has been performed (at block 620) and whether the threshold parameters have converged after the minimum number of iterations (at block 625). In one example, the minimum number of iterations is five iterations. In some examples, determining whether the threshold parameters have converged includes determining whether the threshold parameters determined for a specific number of consecutive iterations (e.g., three consecutive iterations) have changed by less than 10 millivolts. When the threshold parameters have not converged after five iterations, method 600 includes determining whether the maximum number of iterations of block 625 has been performed (at block 630). In one example, the maximum number of iterations is twenty iterations. When twenty iterations of block 625 have been performed and the threshold parameters have not converged, method 600 outputs a fault status indicating that the threshold could not be found (at block 635). In response, electronic processor 140 can provide an indication of the fault status.

[0053] When the threshold parameters have converged after five iterations, method 600 sets relays 280C and 280D to connect the bridge load (at block 640). Method 600 performs a leak test on each of transistor switches 210 - 240 (at block 645). Method 600 includes determining whether a leak has been detected in any of transistor switches 210 - 240 (at block 650). When no leak is detected, method 600 enters the therapy mode (at block 655). In the therapy mode, the pulsed field ablation system is ready (e.g., on standby) to provide therapeutic current through catheter 110. When a leak is detected, method 600 outputs a fault status indicating the transistor switch 210 - 240 in which the leak was found (at block 635). In response, electronic processor 140 can provide an indication of the fault status.

[0054] It should be understood that the various aspects disclosed herein can be combined in combinations different from those specifically presented in the specification and the drawings. It should also be understood that, depending on the example, certain actions or events in any of the processes or methods described herein can be performed in a different order, can be added, combined, or omitted entirely (e.g., not all of the described actions or events may be required to perform these techniques). Additionally, although some aspects of the present disclosure are described for clarity as being performed by a single module or unit, it should be understood that the techniques of the present disclosure can be performed by a combination of units or modules associated with, for example, a medical device.

[0055] 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 on a computer-readable medium as one or more instructions or code and executed by a hardware-based processing unit. The computer-readable medium can include non-transitory computer-readable media corresponding to tangible media, such as data storage media (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 that can be accessed by a computer).

[0056] The instructions can be executed by one or more processors, such as one or more digital signal processors (DSPs), general microprocessors, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Thus, as used herein, the term "electronic processor" can refer to any of the foregoing structures or any other physical structure suitable for implementing the described techniques. Additionally, these techniques can be implemented in whole or in part in one or more circuits or logic elements.

[0057] The following embodiments are a non-limiting list of clauses according to one or more techniques of the present disclosure.

[0058] Embodiment 1. A pulsed field ablation system, the pulsed field ablation system comprising: a bridging circuit configured to deliver bipolar and biphasic voltage pulses to a catheter; a leakage fault protection circuit electrically coupled to the bridging circuit and including a first comparator; and an electronic processor electrically coupled to the bridging circuit and the leakage fault protection circuit and configured to determine a first bias threshold to correct a first bias referenced at the first comparator; set a first threshold parameter of the first comparator based on the first bias threshold and a leakage current parameter of the pulsed field ablation system; and use the first comparator to determine the leakage fault when a detection parameter corresponding to the leakage fault satisfies the first threshold parameter at the first comparator.

[0059] Example 2. The pulsed field ablation system according to Example 1, wherein, in order to determine the first bias threshold, the electronic processor is configured to use a digital-to-analog converter to provide a plurality of bias thresholds to the first comparator; monitor the output of the first comparator for the plurality of bias thresholds; and select the first bias threshold from the plurality of bias thresholds based on the output of the first comparator.

[0060] Example 3. The pulsed field ablation system according to any one of the foregoing embodiments, wherein the electronic processor is further configured to determine the first bias threshold in a first plurality of iterations; and set the first threshold parameter when the first bias threshold converges in the first plurality of iterations.

[0061] Example 4. The pulsed field ablation system according to any one of the foregoing embodiments, wherein the electronic processor is further configured to determine the first bias threshold in a second plurality of iterations; and output a fault state when the first bias threshold does not converge in the second plurality of iterations.

[0062] Example 5. The pulsed field ablation system according to any one of the foregoing embodiments, wherein the first bias referenced at the first comparator corresponds to the bias between the input terminals of the differential amplifier of the leakage fault protection circuit.

[0063] Example 6. The pulsed field ablation system according to any one of the foregoing embodiments, wherein the first comparator is configured to determine the leakage current in the positive direction, wherein the leakage fault protection circuit includes a second comparator configured to determine the leakage current in the negative direction, wherein the electronic processor is configured to determine a second bias threshold to correct a second bias referenced at the second comparator; set a second threshold parameter of the second comparator based on the second bias threshold and the leakage current parameter of the pulsed field ablation system; and use the second comparator to determine the leakage fault in the bridge circuit when a detection parameter corresponding to the leakage fault satisfies the second threshold parameter at the second comparator.

[0064] Example 7. The pulsed field ablation system according to any one of the foregoing examples, wherein the bridging circuit further comprises: a first transistor switch electrically connected between a positive power supply node and a first bridge output node; a second transistor switch electrically connected between the first bridge output node and a negative power supply node; a third transistor switch electrically connected between the positive power supply node and a second bridge output node; and a fourth transistor switch electrically connected between the second bridge output node and the negative power supply node, wherein the electronic processor is electrically connected to the first transistor switch, the second transistor switch, the third transistor switch and the fourth transistor switch, and the electronic processor is configured to selectively open and close the first transistor switch, the second transistor switch, the third transistor switch and the fourth transistor switch.

[0065] Example 8. The pulsed field ablation system according to Example 7, wherein the bridging circuit further comprises: a first relay electrically connecting the first bridge output node to a first patient catheter electrode connector; and a second relay electrically connecting the second bridge output node to a second patient catheter electrode connector; a third relay electrically connecting the first bridge output node to a first patient isolated internal load connector; and a fourth relay electrically connecting the second bridge output node to a second patient isolated internal load connector, wherein the electronic processor is electrically connected to the first relay, the second relay, the third relay and the fourth relay, and the electronic processor is configured to close the first relay and the second relay and open the third relay and the fourth relay during treatment current delivery; and close the third relay and the fourth relay and open the first relay and the second relay during a leak test.

[0066] Example 9. The pulsed field ablation system according to any one of Examples 7 and 8, wherein the electronic processor is configured to close the fourth transistor switch and open the first transistor switch, the second transistor switch and the third transistor switch to determine a leak fault in the first transistor switch.

[0067] Example 10. The pulsed field ablation system according to any one of Examples 7 to 9, the pulsed field ablation system further comprising: a current detection element connected between the first bridge output node and the second bridge output node.

[0068] Example 11. The pulsed field ablation system according to any one of the foregoing examples, wherein the leakage fault protection circuit further includes a differential amplifier, the differential amplifier is connected across the current detection element of the bridge circuit and is configured to receive the voltage drop across the current detection element at the input of the differential amplifier, wherein the first bias is based on the bias between the inputs of the differential amplifier; wherein the first comparator receives the output of the differential amplifier as the detection parameter.

[0069] Example 12. The pulsed field ablation system according to Example 11, wherein the leakage fault protection circuit further includes a digital-to-analog converter connected between the electronic processor and the first comparator, wherein the digital-to-analog converter is configured to provide the first threshold parameter to the first comparator based on a digital input received from the electronic processor.

[0070] Example 13. The pulsed field ablation system according to any one of the foregoing examples, wherein the leakage fault protection circuit is configured to detect a minimum leakage current of at least 10 microamperes.

[0071] Example 14. A method for leakage fault protection in a pulsed field ablation system, the pulsed field ablation system including a bridge circuit configured to deliver bipolar and biphasic voltage pulses to a catheter and a leakage fault protection circuit electrically coupled to the bridge circuit and including a first comparator, the method including: using an electronic processor to determine a first bias threshold to calibrate a first bias referenced at the first comparator; using the electronic processor to set a first threshold parameter of the first comparator based on the first bias threshold and a leakage current parameter of the pulsed field ablation system; and using the first comparator to determine the leakage fault when a detection parameter corresponding to the leakage fault satisfies the first threshold parameter at the first comparator.

[0072] Example 15. The method according to Example 14, wherein in order to determine the first bias threshold, the method further includes: using a digital-to-analog converter to provide a plurality of bias thresholds to the first comparator; monitoring the output of the first comparator for the plurality of bias thresholds; and selecting the first bias threshold from the plurality of bias thresholds based on the output of the first comparator.

[0073] Example 16. The method according to any one of Examples 14 to 15, the method further includes: determining the first bias threshold in a first plurality of iterations; and setting the first threshold parameter when the first bias threshold converges in the first plurality of iterations.

[0074] Example 17. The method according to any one of Examples 14 to 16, the method further comprising: determining the first bias threshold in a second plurality of iterations; and outputting a fault state when the first bias threshold does not converge in the second plurality of iterations.

[0075] Example 18. The method according to any one of Examples 14 to 17, wherein the first bias referenced at the first comparator corresponds to the bias between the input terminals of the differential amplifier of the leakage fault protection circuit.

[0076] Example 19. The method according to any one of Examples 14 to 18, wherein the first comparator is configured to determine a leakage current in a positive direction, wherein the leakage fault protection circuit includes a second comparator configured to determine a leakage current in a negative direction, the method further comprising: determining a second bias threshold to correct a second bias referenced at the second comparator; setting a second threshold parameter of the second comparator based on the second bias threshold and the leakage current parameter of the pulsed field ablation system; and using the second comparator to determine a leakage fault in the bridge circuit when a detection parameter corresponding to the leakage fault satisfies the second threshold parameter at the second comparator.

[0077] Example 20. The method according to any one of Examples 14 to 19, wherein the leakage fault protection circuit is configured to detect a minimum leakage current of at least 10 microamps.

Claims

1. A pulsed field ablation system, the pulsed field ablation system comprising; A bridging circuit configured to deliver bipolar and biphasic voltage pulses to a catheter; A leakage fault protection circuit electrically connected in series to the bridging circuit and including a first comparator; and An electronic processor electrically connected to the bridging circuit and the leakage fault protection circuit and configured to: Determine a first bias threshold to correct a first bias referenced at the first comparator; Set a first threshold parameter of the first comparator based on the first bias threshold and a leakage current parameter of the pulsed field ablation system; And When a detection parameter corresponding to a leakage fault satisfies the first threshold parameter at the first comparator, use the first comparator to determine the leakage fault.

2. The pulsed field ablation system according to claim 1, wherein, in order to determine the first bias threshold, the electronic processor is configured to: Use a digital-to-analog converter to provide a plurality of bias thresholds to the first comparator; Monitor the output of the first comparator for the plurality of bias thresholds; and Select the first bias threshold from the plurality of bias thresholds based on the output of the first comparator.

3. The pulsed field ablation system according to any one of the preceding claims, wherein the electronic processor is further configured to: Determine the first bias threshold in a first plurality of iterations; and Set the first threshold parameter when the first bias threshold converges in the first plurality of iterations.

4. The pulsed field ablation system according to any one of the preceding claims, wherein the electronic processor is further configured to: Determine the first bias threshold in a second plurality of iterations; and Output a fault state when the first bias threshold does not converge in the second plurality of iterations.

5. The pulsed field ablation system according to any one of the preceding claims, wherein the first bias referenced at the first comparator corresponds to a bias between input terminals of a differential amplifier of the leakage fault protection circuit.

6. The pulsed field ablation system according to any one of the preceding claims, wherein the first comparator is configured to determine a leakage current in a positive direction, wherein the leakage fault protection circuit includes a second comparator configured to determine a leakage current in a negative direction, wherein the electronic processor is configured to: Determine a second bias threshold to correct a second bias referenced at the second comparator; Set a second threshold parameter of the second comparator based on the second bias threshold and the leakage current parameter of the pulsed field ablation system; And When the detection parameter corresponding to the leakage fault satisfies the second threshold parameter at the second comparator, use the second comparator to determine the leakage fault in the bridging circuit.

7. The pulsed field ablation system according to any one of the preceding claims, wherein the bridging circuit further includes: A first transistor switch electrically connected between a positive power supply node and a first bridge output node; A second transistor switch electrically coupled between the first bridge output node and the negative power supply node; A third transistor switch electrically coupled between the positive power supply node and the second bridge output node; and A fourth transistor switch electrically coupled between the second bridge output node and the negative power supply node, wherein the electronic processor is electrically coupled to the first transistor switch, the second transistor switch, the third transistor switch, and the fourth transistor switch, and the electronic processor controls to selectively open and close the first transistor switch, the second transistor switch, the third transistor switch, and the fourth transistor switch.

8. The pulsed field ablation system according to claim 7, wherein the bridge circuit further comprises: A first relay that electrically couples the first bridge output node to a first patient catheter electrode connector; A second relay that electrically couples the second bridge output node to a second patient catheter electrode connector; A third relay that electrically couples the first bridge output node to a first patient isolated internal load connector; and A fourth relay that electrically couples the second bridge output node to a second patient isolated internal load connector, wherein the electronic processor is electrically coupled to the first relay, the second relay, the third relay, and the fourth relay, and wherein the electronic processor is configured to: Close the first relay and the second relay and open the third relay and the fourth relay during treatment current delivery; and Close the third relay and the fourth relay and open the first relay and the second relay during a leak test.

9. The pulsed field ablation system according to any one of claims 7 and 8, wherein the electronic processor is configured to: Close the fourth transistor switch and open the first transistor switch, the second transistor switch, and the third transistor switch to determine the leak fault in the first transistor switch.

10. The pulsed field ablation system according to any one of claims 7 to 9, the pulsed field ablation system further comprising: A current detection element connected between the first bridge output node and the second bridge output node.

11. The pulsed field ablation system according to any one of the preceding claims, wherein the leak fault protection circuit further comprises a differential amplifier that is connected across the current detection element of the bridge circuit and is configured to receive a voltage drop across the current detection element at an input of the differential amplifier, wherein the first bias is based on a bias between the inputs of the differential amplifier; wherein the first comparator receives the output of the differential amplifier as the detection parameter.

12. The pulsed field ablation system according to claim 11, wherein the leakage fault protection circuit further includes a digital-to-analog converter connected between the electronic processor and the first comparator, and the digital-to-analog converter is configured to provide the first threshold parameter to the first comparator based on a digital input received from the electronic processor.

13. The pulsed field ablation system according to any one of the preceding claims, wherein the leakage fault protection circuit is configured to detect a minimum leakage current of at least 10 microamperes.

14. A method for leakage fault protection in a pulsed field ablation system, the pulsed field ablation system including a bridging circuit configured to deliver bipolar and biphasic voltage pulses to a catheter and a leakage fault protection circuit electrically coupled to the bridging circuit and including a first comparator, the method comprising: Determining, using an electronic processor, a first bias threshold to correct a first bias referenced at the first comparator; Setting, using the electronic processor, a first threshold parameter of the first comparator based on the first bias threshold and a leakage current parameter of the pulsed field ablation system; And Determining, using the first comparator, the leakage fault when a detection parameter corresponding to the leakage fault satisfies the first threshold parameter at the first comparator.

15. The method according to claim 14, wherein, in order to determine the first bias threshold, the method further comprises: Providing, using a digital-to-analog converter, a plurality of bias thresholds to the first comparator; Monitoring an output of the first comparator for the plurality of bias thresholds; And Selecting, based on the output of the first comparator, the first bias threshold from the plurality of bias thresholds.

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