Patent Publication Number: US-2022233237-A1

Title: Voltage Controlled Pulse Sequences for Irreversible Electroporation Ablations

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority to Provisional Application No. 63/142,133, filed Jan. 27, 2021, which is herein incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to medical apparatus, systems, and methods for ablating tissue in a patient. More specifically, the present disclosure relates to medical apparatus, systems, and methods for ablation of tissue by electroporation. 
     BACKGROUND 
     Ablation procedures are used to treat many different conditions in patients. Ablation may be used to treat cardiac arrhythmias, benign tumors, cancerous tumors, and to control bleeding during surgery. Usually, ablation is accomplished through thermal ablation techniques including radio-frequency (RF) ablation and cryoablation. In RF ablation, a probe is inserted into the patient and radio frequency waves are transmitted through the probe to the surrounding tissue. The radio frequency waves generate heat, which destroys surrounding tissue and cauterizes blood vessels. In cryoablation, a hollow needle or cryoprobe is inserted into the patient and cold, thermally conductive fluid is circulated through the probe to freeze and kill the surrounding tissue. RF ablation and cryoablation techniques indiscriminately kill tissue through cell necrosis, which may damage or kill otherwise healthy tissue, such as tissue in the esophagus, phrenic nerve cells, and tissue in the coronary arteries. 
     Another ablation technique uses electroporation. In electroporation, or electro-permeabilization, an electric field is applied to cells to increase the permeability of the cell membrane. The electroporation may be reversible or irreversible, depending on the strength of the electric field. If the electroporation is reversible, the increased permeability of the cell membrane may be used to introduce chemicals, drugs, and/or deoxyribonucleic acid (DNA) into the cell, prior to the cell healing and recovering. If the electroporation is irreversible, the affected cells are killed through apoptosis. 
     Irreversible electroporation (IRE) may be used as a nonthermal ablation technique. In IRE, trains of short, high voltage pulses are used to generate electric fields that are strong enough to kill cells through apoptosis. In ablation of cardiac tissue, IRE may be a safe and effective alternative to the indiscriminate killing of thermal ablation techniques, such as RF ablation and cryoablation. IRE may be used to kill targeted tissue, such as myocardium tissue, by using an electric field strength and duration that kills the targeted tissue but does not permanently damage other cells or tissue, such as non-targeted myocardium tissue, red blood cells, vascular smooth muscle tissue, endothelium tissue, and nerve cells. 
     SUMMARY 
     As recited in examples, Example 1 is an electroporation ablation system for treating targeted tissue in a patient. The electroporation ablation system comprises an ablation catheter including: catheter electrodes configured to generate electric fields in the targeted tissue in response to a plurality of electrical pulse sequences delivered in a plurality of therapy sections; a controller configured to: receive a first pulse voltage of a first electrical pulse sequence measured during a first therapy section of the plurality of therapy sections; determine a charge voltage based on the first pulse voltage; and an electroporation generator. The electroporation generator is operatively coupled to the catheter electrodes and the controller and configured to deliver a second electrical pulse sequence at a controlled pulse voltage for a second therapy section of the plurality of therapy sections, the second therapy section being after the first therapy section, the controlled pulse voltage being associated with the charge voltage. 
     Example 2 is the electroporation ablation system of Example 1, wherein the electroporation generator comprises a capacitor bank and the electroporation generator is configured to charge the capacitor bank to a voltage level of the charge voltage before a start of the second therapy section. 
     Example 3 is the electroporation ablation system of Example 1 or 2, wherein the first electrical pulse sequence comprises a plurality of first electrical pulses. 
     Example 4 is the electroporation ablation system of Example 3, wherein the first pulse voltage comprises one or more pulse voltages of the plurality of first electrical pulses measured during the first therapy section. 
     Example 5 is the electroporation ablation system of any one of Examples 1-4, wherein the controller is further configured to receive a first pulse current of the first electrical pulse sequence delivered during the first therapy section, wherein the controller is further configured to determine the charge voltage based on the first pulse voltage and the first pulse current. 
     Example 6 is the electroporation ablation system of Example 5, wherein the controller is further configured to determine a first tissue impedance based on the first pulse voltage and the first pulse current. 
     Example 7 is the electroporation ablation system of Example 6, wherein the controlled pulse voltage is a portion of the charge voltage. 
     Example 8 is the electroporation ablation system of Example 7, wherein a ratio of the controlled pulse voltage and the charge voltage is associated with the first tissue impedance. 
     Example 9 is the electroporation ablation system of any one of Examples 1-8, wherein the electroporation generator is further configured to deliver a scan electrical pulse sequence at a scan voltage during a scan section prior to the plurality of therapy sections, wherein the controller is further configured to determine an initial tissue impedance based on an initial pulse voltage of the scan electrical pulse sequence and an initial pulse current of the scan electrical pulse sequence measured during the scan section, wherein the controller is further configured to determine an initial charge voltage based on the initial tissue impedance. 
     Example 10 is the electroporation ablation system of Example 9, wherein the scan voltage is less than the controlled pulse voltage. 
     Example 11 is the electroporation ablation system of Example 9, wherein the scan electrical pulse sequence includes a single non-ablative electrical pulse. 
     Example 12 is method of using an electroporation ablation device. The method includes the steps of: disposing a catheter of the electroporation ablation device anatomically proximate to a target ablation location, the catheter comprising one or more catheter electrodes and configured to generate electric fields in response to a plurality of electrical pulse sequences delivered in a plurality of therapy sections; receiving a first pulse voltage of a first electrical pulse sequence measured during a first therapy section of the plurality of therapy sections; determining a charge voltage based on the first pulse voltage; and delivering a second electrical pulse sequence at a controlled pulse voltage for a second therapy section of the plurality of therapy sections, the second therapy section being after the first therapy section, the controlled pulse voltage being associated with the charge voltage. 
     Example 13 is the method of Example 12, further comprising: receiving a first pulse current of first electrical pulse sequence measured during the first therapy section, wherein determining a charge voltage comprises determining the charge voltage based on the first pulse voltage and the first pulse current. 
     Example 14 is the method of Example 13, further comprising: determining a first tissue impedance based on the first pulse voltage and the first pulse current, wherein determining a charge voltage comprises determining the charge voltage based on the first tissue impedance. 
     Example 15 is the method of any one of Examples 12-14, further comprising: delivering a scan electrical pulse sequence during a scan section; receiving an initial pulse voltage of the scan electrical pulse sequence measured during the scan section; receiving an initial pulse current of the scan electrical pulse sequence measured during the scan section; and determining an initial tissue impedance based on the initial pulse voltage and the initial pulse current measured, wherein the scan section is before the first therapy section, wherein the scan electrical pulse sequence is at a scan pulse voltage lower than the controlled pulse voltage. 
     Example 16 is an electroporation ablation system for treating targeted tissue in a patient. The electroporation ablation system comprising: an ablation catheter including: catheter electrodes configured to generate electric fields in the targeted tissue in response to a plurality of electrical pulse sequences delivered in a plurality of therapy sections; a controller configured to receive a first pulse voltage of a first electrical pulse sequence measured during a first therapy section of the plurality of therapy sections; determine a charge voltage based on the first pulse voltage; and an electroporation generator. The electroporation generator is operatively coupled to the catheter electrodes and the controller and configured to deliver a second electrical pulse sequence at a controlled pulse voltage for a second therapy section of the plurality of therapy sections, the second therapy section being after the first therapy section, the controlled pulse voltage being associated with the charge voltage. 
     Example 17 is the electroporation ablation system of Example 16, wherein the electroporation generator comprises a capacitor bank and the electroporation generator is configured to charge the capacitor bank to a voltage level of the charge voltage before a start of the second therapy section. 
     Example 18 is the electroporation ablation system of Example 16, wherein the first electrical pulse sequence comprises a plurality of first electrical pulses. 
     Example 19 is the electroporation ablation system of Example 18, wherein the first pulse voltage comprises one or more pulse voltages of the plurality of first electrical pulses measured during the first therapy section. 
     Example 20 is the electroporation ablation system of Example 16, wherein the controller is further configured to receive a first pulse current of a first electrical pulse sequence delivered during the first therapy section, wherein the controller is further configured to determine the charge voltage based on the first pulse voltage and the first pulse current. 
     Example 21 is the electroporation ablation system of Example 20, wherein the controller is further configured to determine a first tissue impedance based on the first pulse voltage and the first pulse current. 
     Example 22 is the electroporation ablation system of Example 21, wherein the controlled pulse voltage is a portion of the charge voltage. 
     Example 23 is the electroporation ablation system of Example 22, wherein a ratio of the controlled pulse voltage and the charge voltage is associated with the first tissue impedance. 
     Example 24 is the electroporation ablation system of Example 16, wherein the electroporation generator is further configured to deliver a scan electrical pulse sequence at a scan voltage during a scan section prior to the plurality of therapy sections, wherein the controller is further configured to determine an initial tissue impedance based on an initial pulse voltage of the scan electrical pulse sequence and an initial pulse current of the scan electrical pulse sequence measured during the scan section, wherein the controller is further configured to determine an initial charge voltage based on the initial tissue impedance. 
     Example 25 is the electroporation ablation system of Example 24, wherein the scan voltage is less than the controlled pulse voltage. 
     Example 26 is the electroporation ablation system of Example 24, wherein the scan electrical pulse sequence includes a single non-ablative electrical pulse. 
     Example 27 is the electroporation ablation system of Example 16, wherein the electroporation generator comprises a plurality of capacitor banks, wherein the electroporation generator is configured to charge at least one of the plurality of capacitor banks to a voltage level individually. 
     Example 28 is the electroporation ablation system of Example 27, wherein the electroporation generator is configured to use a first capacitor bank of the plurality of capacitor banks to deliver a pulse sequence for a specific therapy section of the plurality of therapy sections and charge a second capacitor bank of the plurality of capacitor banks to a voltage level of a determined charge voltage before a start of a therapy section immediately after the specific therapy section of the plurality of therapy sections. 
     Example 29 is the electroporation ablation system of Example 27, wherein the catheter electrodes comprise a plurality of electrode pairs, wherein each capacitor bank of the plurality of capacitor banks is operatively coupled to one or more electrode pairs of the plurality of electrode pairs. 
     Example 30 is the electroporation ablation system of Example 29, wherein the controller is configured to determine a bank charge voltage for each capacitor bank of the plurality of capacitor banks. 
     Example 31 is a method of using an electroporation ablation device. The method includes the step of: disposing a catheter of the electroporation ablation device anatomically proximate to a target ablation location, the catheter comprising one or more catheter electrodes and configured to generate electric fields in response to a plurality of electrical pulse sequences delivered in a plurality of therapy sections; receiving a first pulse voltage of a first electrical pulse sequence measured during a first therapy section of the plurality of therapy sections; determining a charge voltage based on the first pulse voltage; and delivering a second electrical pulse sequence at a controlled pulse voltage for a second therapy section of the plurality of therapy sections, the second therapy section being after the first therapy section, the controlled pulse voltage being associated with the charge voltage. 
     Example 32 is the method of Example 31, further comprising: receiving a first pulse current of first electrical pulse sequence measured during the first therapy section, wherein determining a charge voltage comprises determining the charge voltage based on the first pulse voltage and the first pulse current. 
     Example 33 is the method of Example 32, further comprising: determining a first tissue impedance based on the first pulse voltage and the first pulse current, wherein determining a charge voltage comprises determining the charge voltage based on the first tissue impedance. 
     Example 34 is the method of Example 30, further comprising: delivering a scan electrical pulse sequence during a scan section; receiving an initial pulse voltage of the scan electrical pulse sequence measured during the scan section; receiving an initial pulse current of the scan electrical pulse sequence measured during the scan section; and determining an initial tissue impedance based on the initial pulse voltage and the initial pulse current measured, wherein the scan section is before the first therapy section, wherein the scan electrical pulse sequence is at a scan pulse voltage lower than the controlled pulse voltage. 
     Example 35 is the method of Example 34, wherein the scan pulse voltage is at a non-ablative voltage level. 
     While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts an illustrative system diagram for an electroporation ablation system, in accordance with embodiments of the subject matter of the disclosure. 
         FIG. 2A  is an illustrative graph of the pulse voltages changing over a number of therapy sections without adjusting the charge voltage. 
         FIG. 2B  is an illustrative graph of the pulse currents changing over a number of therapy sections without adjusting the charge voltage. 
         FIG. 2C  is an illustrative graph of the tissue impedances changing over a number of therapy sections. 
         FIG. 3  is an illustrative example of a plurality of scan and therapy sections related to the cardiac beats. 
         FIG. 4  is an illustrative schematic circuit diagram of an electroporation generator in use for an electroporation ablation section, in accordance with certain embodiments of the present disclosure. 
         FIGS. 5A and 5B  are diagrams illustrating example embodiments of catheters that can be used for electroporation, including ablation by irreversible electroporation, in accordance with embodiments of the subject matter of the disclosure. 
         FIG. 6  is an example flow diagram depicting an illustrative method of using an electroporation ablation device, in accordance with some embodiments of the present disclosure. 
     
    
    
     While the invention is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the invention to the particular embodiments described. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION 
     As the terms are used herein with respect to measurements (e.g., dimensions, characteristics, attributes, components, etc.), and ranges thereof, of tangible things (e.g., products, inventory, etc.) and/or intangible things (e.g., data, electronic representations of currency, accounts, information, portions of things (e.g., percentages, fractions), calculations, data models, dynamic system models, algorithms, parameters, etc.), “about” and “approximately” may be used, interchangeably, to refer to a measurement that includes the stated measurement and that also includes any measurements that are reasonably close to the stated measurement, but that may differ by a reasonably small amount such as will be understood, and readily ascertained, by individuals having ordinary skill in the relevant arts to be attributable to measurement error; differences in measurement and/or manufacturing equipment calibration; human error in reading and/or setting measurements; adjustments made to optimize performance and/or structural parameters in view of other measurements (e.g., measurements associated with other things); particular implementation scenarios; imprecise adjustment and/or manipulation of things, settings, and/or measurements by a person, a computing device, and/or a machine; system tolerances; control loops; machine-learning; foreseeable variations (e.g., statistically insignificant variations, chaotic variations, system and/or model instabilities, etc.); preferences; and/or the like. 
     Although illustrative methods may be represented by one or more drawings (e.g., flow diagrams, communication flows, etc.), the drawings should not be interpreted as implying any requirement of, or particular order among or between, various steps disclosed herein. However, certain some embodiments may require certain steps and/or certain orders between certain steps, as may be explicitly described herein and/or as may be understood from the nature of the steps themselves (e.g., the performance of some steps may depend on the outcome of a previous step). Additionally, a “set,” “subset,” or “group” of items (e.g., inputs, algorithms, data values, etc.) may include one or more items, and, similarly, a subset or subgroup of items may include one or more items. A “plurality” means more than one. 
     As used herein, the term “based on” is not meant to be restrictive, but rather indicates that a determination, identification, prediction, calculation, and/or the like, is performed by using, at least, the term following “based on” as an input. For example, predicting an outcome based on a particular piece of information may additionally, or alternatively, base the same determination on another piece of information. 
     Cryo energy and radio-frequency (RF) energy kill tissues indiscriminately through cell necrosis, which can damage the esophagus, the phrenic nerve, coronary arteries, in addition to other undesired effects. Irreversible electroporation (IRE) uses high voltage, short (e.g., 100 microseconds or shorter) pulses to kill cells through apoptosis. IRE can be targeted to kill myocardium, sparing other adjacent tissues including the esophageal vascular smooth muscle and endothelium. After IRE ablation commences, pore are induced in cell membranes and intracellular fluids are released into the extracellular matrix, such that tissue conductivity is increased and tissue impedance is decreased. Changes in tissue impedance occur rapidly, within the course of multiple IRE therapy sections, also referred to as therapy bursts or therapy sections. A therapy section (e.g., for a duration of 10 milliseconds) may include a plurality of electrical pulses (e.g., 20 pulses, 30 pulses, etc.) generated and delivered by an electroporation generator. If the electroporation generator does not adjust its charge voltage provided by source component(s), the therapeutic pulse voltage drops over the course of the IRE ablation by as much as 40%. Since the IRE treatment depends on the electric field, the drop of the pulse voltage can potentially impact the effectiveness of the IRE treatment. 
     The present disclosure describes systems, devices and methods for implementing ablation with voltage controlled electrical pulse sequences. In some embodiments, the pulse voltage and/or pulse current are measured during therapy sections and used to determine a charge voltage for the next therapy section, such that electrical pulses each has a voltage close to a target pulse voltage during the next therapy section. As used herein, the charge voltage refers to the voltage generated by the electroporation generator, which can be the voltage of one or more capacitor banks or other power source. In some embodiments, the tissue impedance is computed based on the pulse voltage and pulse current. In some cases, the tissue impedance is used to determine the charge voltage. 
       FIG. 1  depicts an illustrative system diagram for an electroporation ablation system  100 , in accordance with embodiments of the subject matter of the disclosure. The electroporation ablation system  100  includes one or more electroporation ablation catheters  110 , a controller  120 , one or more sensors  130 , an electroporation generator  140 , and a memory  160 . In embodiments, the electroporation ablation system  100  is configured to deliver electric field energy to target tissue in a patient&#39;s heart to create tissue apoptosis, rendering the tissue incapable of conducting electrical signals. In some cases, the electroporation ablation system  100  may connect with other system(s)  170 , for example, a mapping system, an electrophysiology system, and/or the like. 
     In some embodiments, the catheter(s)  110  can be various types and forms of electroporation catheter such as, for example, linear ablation catheters, focal ablation catheters, circumferential catheters, and/or the like. In embodiments, the electroporation ablation system  100  includes an introducer sheath (not shown) operable to provide a delivery conduit through which the electroporation ablation catheter  110  can be deployed to specific target sites within a patient&#39;s cardiac chamber. In some cases, the electroporation ablation catheter  110  includes a shaft having a distal end and catheter electrodes situated at the distal end of the shaft and spatially arranged to generate electric fields in the targeted tissue in response to a plurality of electrical pulse sequences delivered in a plurality of therapy sections. In some cases, the catheter(s)  110  include deflectable catheter(s). 
     In some cases, the catheter(s)  110  includes one or more electrodes to generate an electric field for ablation. The electroporation generator  140 , also referred to as a pulse generator, is configured to generate ablative pulse/energy, or referred to as electroporation pulse/energy, to be delivered to electrodes of the catheter(s)  110 . The electroporation pulse is typically high voltage and short pulse. The controller  120  is configured to control functional aspects of the electroporation ablation system  100 . In embodiments, the electroporation controller  120  is configured to control the electroporation generator  140  on the generation and delivery of ablative energy to electrodes of the catheter(s)  110  is individually addressable. In one case, each of the one or more electrodes of the catheter(s)  110 . In such case, the controller  120  may control the ablative energy delivery to each electrode. 
     In some embodiments, the electroporation controller  120  can control an output voltage (i.e. the pulse voltage of pulse sequences) generated by the electroporation generator  140 . In some embodiments, the electroporation generator  140  includes a capacitor bank  145 , which can be charged and discharged for the generation of the charge voltage to generate electrical pulses. In some cases, the electroporation controller  120  can determine a charge voltage of the capacitor bank  145  in response to the sensing data. In some implementations, the charge voltage is the voltage generated by the electricity source component(s) (e.g., the capacitor bank  145 ) of the electroporation generator  140 . In some cases, the capacitor bank  145  includes one or more capacitor banks such that at least one capacitor bank is to provide the charge voltage for the current therapy section (e.g., the current therapy burst) of the electrical pulses and at least one capacitor bank is to be charged for providing the charge voltage for the next therapy section (e.g., the next therapy burst) of electrical pulses. In some embodiments, the electroporation generator  140  has an internal impedance, or referred to as generator impedance. In some cases, the electroporation generator  140  can generate electrical pulses at a pulse voltage, or referred to as an output voltage, which is lower than the charge voltage because of the generator impedance. In some cases, the pulse voltage is a portion of the charge voltage. In some cases, a user can set up a target pulse voltage via an interface to the controller (e.g., a user interface, a software interface, a system interface). 
     In some embodiments, the electroporation controller  120  receives sensor data collected by sensor(s) of catheter(s) and/or sensors  130  placed proximate to the ablation location. In some cases, the controller  120  is configured to determine a tissue impedance based upon the measured pulse voltage and/or pulse current proximate to the electroporation location. In some cases, the controller  120  is configured to determine a charge voltage based on the measured pulse voltage and/or the tissue impedance. In some cases, the controller  120  is configured to determine a charge voltage based on the target pulse voltage, the generator impedance, and/or the tissue impedance. In some cases, the controller  120  is configured to control the capacitor bank  145  based on the determined charge voltage. 
     In some embodiments, the controller  120  is configured to receive a first pulse voltage and/or a first pulse current of a first electrical pulse sequence delivered during a first therapy section of a plurality of therapy sections. In some implementations, an electrical pulse sequence includes a plurality of the electrical/electroporation pulses for a therapy section. In some cases, the first pulse voltage and/or the first pulse current are measured for a last electrical pulse in a therapy section. In some cases, the first pulse voltage and/or the first pulse current are measured for a first electrical pulse in a therapy section. In some cases, the first pulse voltage and/or the first pulse current are determined based on measurements of a plurality of electrical pulses in a therapy section. In one example, the first pulse voltage and/or the first pulse current are an average voltage and/or current measured for a plurality of electrical pulses in a therapy section respectively. In one example, the first pulse voltage and/or the first pulse current are an average voltage and/or current measured for all the electrical pulses in the therapy section respectively. 
     In some embodiments, the controller  120  determines a charge voltage based on the first pulse voltage. In some cases, the controller  120  determines a charge voltage difference between the determined charge voltage and the current charge level of the capacitor bank  145 . In some cases, the controller  120  determines a charge voltage difference based on a percentage difference between the measured pulse voltage and the target pulse voltage. For example, the charge voltage difference is determined by the current charge voltage multiplied by a percentage difference between the measured pulse voltage and the target pulse voltage. In some cases, the controller  120  controls or sets the capacitor bank  145  based on the determined charge voltage and/or the charge voltage difference. In some embodiments, the electroporation generator  140  is operatively coupled to the catheter electrodes and the controller  120  and configured to deliver a second electrical pulse sequence at a controlled pulse voltage for a second therapy section of the plurality of therapy sections, where the second therapy section is after the first therapy section. In some cases, the controlled pulse voltage is based at least in part on a determined charge voltage. In some cases, the capacitor bank  145  is set at the level of the determined charge voltage. 
     In some embodiments, the controller  120  is configured to determine the charge voltage for the second therapy section based on the first pulse voltage and the first pulse current. In some cases, the controller  120  is configured to determine a first tissue impedance based on the first pulse voltage and the first pulse current. In some cases, the controller  120  is configured to determine the charge voltage based on the first tissue impedance and the target pulse voltage. In some cases, the controller  120  is configured to determine the charge voltage based on the first tissue impedance, the target pulse voltage, and the generator impedance. In some embodiments, the electroporation generator  140  is configured to receive the signal indicative of the determined charge voltage and charge the capacitor bank  145  to the level of the determined charged voltage before the start of the next therapy section. In some cases, the controlled pulse voltage is a portion of the determined charge voltage. In some cases, the ratio of the controlled pulse voltage and the determined charge voltage is associated with the first tissue impedance. 
     In embodiments, the controller  120  is configured to measure pulse voltages and/or pulse currents during each or some of the therapy sections to determine the charge voltages for the subsequent therapy sections. In some embodiments, the controller  120  is configured to store pulse voltages, pulse currents, charge voltages, generator impedance(s), and/or tissue impedances in the data repository  165 .  FIG. 2A  is an illustrative graph of the pulse voltages changing over a number of therapy sections without adjusting the charge voltage. As shown, the pulse voltage decreases over the sequence of therapy sections.  FIG. 2B  is an illustrative graph of the pulse currents changing over a number of therapy sections without adjusting the charge voltage. As shown, the pulse current increases over the sequence of therapy sections.  FIG. 2C  is an illustrative graph of the tissue impedances changing over a number of therapy sections. As shown, the tissue impedance decreases over the sequence of therapy sections. 
     In some embodiments, the electroporation generator  140  is configured to deliver a scan electrical pulse sequence at a scan voltage during a scan section prior to the plurality of therapy sections, where the scan voltage is lower than the therapeutic voltage (e.g., the target pulse voltage). In some cases, the scan voltage is a non-ablative voltage level. In some cases, the scan electrical pulse sequence is a single non-ablative electrical pulse. In some cases, the controller  120  is configured to determine an initial tissue impedance based on an initial pulse voltage of the scan electrical pulse sequence and an initial pulse current of the scan electrical pulse sequence measured during the scan section. In some cases, the controller  120  is configured to determine an initial charge voltage based on the initial tissue impedance. In some cases, the controller  120  is configured to determine an initial charge voltage based on the initial tissue impedance and the target pulse voltage. In some cases, the controller  120  is configured to determine an initial charge voltage based on the initial tissue impedance, the target pulse voltage, and the generator impedance. 
       FIG. 3  is an illustrative example of a plurality of scan and therapy sections related to the cardiac beats. As illustrated, the therapy sections  330  are provided between cardiac beats shown in the waveform  310 . In this example, the scan section  320  is prior to the therapy sections  330 . In some embodiments, the electroporation generator  140  is configured to charge the capacitor bank  145  to the determined charge voltage before the start of a respective therapy section. For example, with a cardiac beat rate of 90 BPM (beat-per-minute), the electroporation generator  140  is configured to charge the capacitor bank  145  to the level of the determined charge voltage within 667 milliseconds. In some cases, the electroporation controller  120  is configured to model the electric fields that can be generated by the catheter  110 , which often includes consideration of the physical characteristics of the electroporation ablation catheter  110  including the electrodes and spatial relationships of the electrodes on the electroporation ablation catheter  110 . In embodiments, the electroporation controller  120  is configured to control the electric field strength of the electric field formed by the electrodes of the catheter  110  to be no higher than 1500 volts per centimeter. 
     In some embodiments, the catheter  110  includes two or more electrode pairs of and the capacitor bank  145  includes two or more capacitor banks, where each capacitor bank in the capacitor bank  145  (e.g., a group of capacitor banks) is configured to charge one or more electrode pairs. In some cases, the electroporation controller  120  is configured to receive measured pulse voltages from the electrode pairs and determine a charge voltage for each respective capacitor bank for charging the electrode pairs. By way of an example, the capacitor bank  145  includes two capacitor banks (e.g., Bank A, Bank B), each capacitor bank is configured to charge two electrode pairs (e.g., Bank A for charging Electrode Pairs 1 &amp; 2, Bank B for charging Electrode Pairs 3 &amp; 4). In this example, the electroporation controller  120  is configured to determine a charge voltage for Bank A based on the measured pulse voltage of the Electrode Pairs 1 &amp; 2, and determine a charge voltage for Bank B based on the measured pulse voltage of the Electrode Pairs 3 &amp; 4. 
     In embodiments, the electroporation controller  120  includes one or more controllers, microprocessors, and/or computers that execute code out of memory  160 , for example, non-transitory machine readable medium, to control and/or perform the functional aspects of the electroporation ablation system  100 . In embodiments, the memory  160  can be part of the one or more controllers, microprocessors, and/or computers, and/or part of memory capacity accessible through a network, such as the world wide web. In embodiments, the memory  160  comprises a data repository  165 , which is configured to store ablation data (e.g., location, energy, etc.), measured pulse voltages, measured pulse currents, tissue impedances, generator impedance, sensed data, treatment plan data, charge voltages, and/or the like. 
     In embodiments, the other systems  170  includes an electro-anatomical mapping (EAM) system. In some cases, the EAM system is operable to track the location of the various functional components of the electroporation ablation system  100 , and to generate high-fidelity three-dimensional anatomical and electro-anatomical maps of the cardiac chambers of interest. In embodiments, the EAM system can be the RHYTHMIA™ HDx mapping system marketed by Boston Scientific Corporation. Also, in embodiments, the mapping and navigation controller of the EAM system includes one or more controllers, microprocessors, and/or computers that execute code out of memory to control and/or perform functional aspects of the EAM system. 
     The EAM system generates a localization field, via a field generator, to define a localization volume about the heart, and one or more location sensors or sensing elements on the tracked device(s), e.g., the electroporation ablation catheter  110 , generate an output that can be processed by a mapping and navigation controller to track the location of the sensor, and consequently, the corresponding device, within the localization volume. In one embodiment, the device tracking is accomplished using magnetic tracking techniques, whereby the field generator is a magnetic field generator that generates a magnetic field defining the localization volume, and the location sensors on the tracked devices are magnetic field sensors. 
     In some embodiments, impedance tracking methodologies may be employed to track the locations of the various devices. In such embodiments, the localization field is an electric field generated, for example, by an external field generator arrangement, e.g., surface electrodes, by intra-body or intra-cardiac devices, e.g., an intracardiac catheter, or both. In these embodiments, the location sensing elements can constitute electrodes on the tracked devices that generate outputs received and processed by the mapping and navigation controller to track the location of the various location sensing electrodes within the localization volume. 
     In embodiments, the EAM system is equipped for both magnetic and impedance tracking capabilities. In such embodiments, impedance tracking accuracy can, in some instances be enhanced by first creating a map of the electric field induced by the electric field generator within the cardiac chamber of interest using a probe equipped with a magnetic location sensor, as is possible using the aforementioned RHYTHMIA HDx™ mapping system. One exemplary probe is the INTELLAMAP ORION™ mapping catheter marketed by Boston Scientific Corporation. 
     Regardless of the tracking methodology employed, the EAM system utilizes the location information for the various tracked devices, along with cardiac electrical activity acquired by, for example, the electroporation ablation catheter  110  or another catheter or probe equipped with sensing electrodes, to generate, and display via a display, detailed three-dimensional geometric anatomical maps or representations of the cardiac chambers as well as electro-anatomical maps in which cardiac electrical activity of interest is superimposed on the geometric anatomical maps. Furthermore, the EAM system can generate a graphical representation of the various tracked devices within the geometric anatomical map and/or the electro-anatomical map. 
     According to embodiments, various components (e.g., the controller  120 ) of the electroporation ablation system  100  may be implemented on one or more computing devices. A computing device may include any type of computing device suitable for implementing embodiments of the disclosure. Examples of computing devices include specialized computing devices or general-purpose computing devices such as workstations, servers, laptops, portable devices, desktop, tablet computers, hand-held devices, general-purpose graphics processing units (GPGPUs), and the like, all of which are contemplated within the scope of  FIG. 1  with reference to various components of the system  100 . 
     In some embodiments, a computing device includes a bus that, directly and/or indirectly, couples the following devices: a processor, a memory, an input/output (I/O) port, an I/O component, and a power supply. Any number of additional components, different components, and/or combinations of components may also be included in the computing device. The bus represents what may be one or more busses (such as, for example, an address bus, data bus, or combination thereof). Similarly, in some embodiments, the computing device may include a number of processors, a number of memory components, a number of I/O ports, a number of I/O components, and/or a number of power supplies. Additionally, any number of these components, or combinations thereof, may be distributed and/or duplicated across a number of computing devices. 
     In some embodiments, the memory  160  includes computer-readable media in the form of volatile and/or nonvolatile memory, transitory and/or non-transitory storage media and may be removable, nonremovable, or a combination thereof. Media examples include Random Access Memory (RAM); Read Only Memory (ROM); Electronically Erasable Programmable Read Only Memory (EEPROM); flash memory; optical or holographic media; magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices; data transmissions; and/or any other medium that can be used to store information and can be accessed by a computing device such as, for example, quantum state memory, and/or the like. In some embodiments, the memory  160  stores computer-executable instructions for causing a processor (e.g., the controller  120 ) to implement aspects of embodiments of system components discussed herein and/or to perform aspects of embodiments of methods and procedures discussed herein. 
     Computer-executable instructions may include, for example, computer code, machine-useable instructions, and the like such as, for example, program components capable of being executed by one or more processors associated with a computing device. Program components may be programmed using any number of different programming environments, including various languages, development kits, frameworks, and/or the like. Some or all of the functionality contemplated herein may also, or alternatively, be implemented in hardware and/or firmware. 
     The data repository  165  may be implemented using any one of the configurations described below. A data repository may include random access memories, flat files, XML files, and/or one or more database management systems (DBMS) executing on one or more database servers or a data center. A database management system may be a relational (RDBMS), hierarchical (HDBMS), multidimensional (MDBMS), object oriented (ODBMS or OODBMS) or object relational (ORDBMS) database management system, and the like. The data repository may be, for example, a single relational database. In some cases, the data repository may include a plurality of databases that can exchange and aggregate data by data integration process or software application. In an exemplary embodiment, at least part of the data repository  165  may be hosted in a cloud data center. In some cases, a data repository may be hosted on a single computer, a server, a storage device, a cloud server, or the like. In some other cases, a data repository may be hosted on a series of networked computers, servers, or devices. In some cases, a data repository may be hosted on tiers of data storage devices including local, regional, and central. 
     Various components of the system  100  can communicate via or be coupled to via a communication interface, for example, a wired or wireless interface. The communication interface includes, but not limited to, any wired or wireless short-range and long-range communication interfaces. The wired interface can use cables, umbilicals, and the like. The short-range communication interfaces may be, for example, local area network (LAN), interfaces conforming known communications standard, such as Bluetooth® standard, IEEE 802 standards (e.g., IEEE 802.11), a ZigBee® or similar specification, such as those based on the IEEE 802.15.4 standard, or other public or proprietary wireless protocol. The long-range communication interfaces may be, for example, wide area network (WAN), cellular network interfaces, satellite communication interfaces, etc. The communication interface may be either within a private computer network, such as intranet, or on a public computer network, such as the internet. 
       FIG. 4  is an illustrative schematic circuit diagram  400  of an electroporation generator  430  in use for an electroporation ablation section, in accordance with certain embodiments of the present disclosure. In some implementations, other components can be included in the circuit diagram  400 . In the circuit diagram  400 , the electroporation generator  430  delivers electric pulse sequences at pulse_voltage  420  to target tissues. The target tissues have a tissue impedance  440 , which is changing during the electroporation ablation section. In the simplified schematic diagram, the electroporation generator  430  includes a voltage source  432 , a bulk capacitance  435  (e.g., a capacitor bank), and the generator impedance  437 . In this example, the generator impedance  437  represents the overall impedance of the electroporation generator  430 . In embodiments, the electroporation ablation section includes a plurality of therapy sections. In some embodiments, the voltage source  432  can charge the bulk capacitance  435  between therapy sections to adjust the charge_voltage  410  and thereby adjust the pulse_voltage  420  to reach the target pulse voltage. 
     In some embodiments, during a therapy section, a pulse_voltage or a plurality of pulse voltages are measured. In one example, the pulse_voltage  420  has a relation with the charge_voltage  410  represented in equation (1) below: 
     
       
         
           
             
               
                 
                   
                     
                       V 
                       ⁢ 
                       o 
                       ⁢ 
                       l 
                       ⁢ 
                       t 
                       ⁢ 
                       a 
                       ⁢ 
                       g 
                       ⁢ 
                       
                         e 
                         Pulse 
                       
                     
                     = 
                     
                       
                         
                           Voltage 
                           Charge 
                         
                         * 
                         
                           Impedance 
                           
                             T 
                             ⁢ 
                             i 
                             ⁢ 
                             s 
                             ⁢ 
                             s 
                             ⁢ 
                             u 
                             ⁢ 
                             e 
                           
                         
                       
                       
                         
                           Impedance 
                           
                             G 
                             ⁢ 
                             e 
                             ⁢ 
                             n 
                             ⁢ 
                             e 
                             ⁢ 
                             r 
                             ⁢ 
                             a 
                             ⁢ 
                             t 
                             ⁢ 
                             o 
                             ⁢ 
                             r 
                           
                         
                         + 
                         
                           Impedance 
                           
                             T 
                             ⁢ 
                             i 
                             ⁢ 
                             s 
                             ⁢ 
                             s 
                             ⁢ 
                             u 
                             ⁢ 
                             e 
                           
                         
                       
                     
                   
                   , 
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
           
         
       
     
     where Voltage Pulse  is the pulse_voltage  420 , Voltage charge  is the charge_voltage  410 , Impedance Tissue  represents the tissue impedance  440 , and Impedance Generator  is the generator impedance  437 . Additionally, in one example, the charge_voltage  410  can be determined by the pulse_voltage  420  measured during the therapy sections, according the equation (2) below: 
     
       
         
           
             
               
                 
                   
                     
                       Voltage 
                       Charge 
                     
                     = 
                     
                       
                         
                           
                             
                               
                                 Volta 
                                 ⁢ 
                                 
                                   ge 
                                   Pulse 
                                 
                                 * 
                                 
                                   Impedance 
                                   
                                     G 
                                     ⁢ 
                                     e 
                                     ⁢ 
                                     n 
                                     ⁢ 
                                     e 
                                     ⁢ 
                                     r 
                                     ⁢ 
                                     a 
                                     ⁢ 
                                     t 
                                     ⁢ 
                                     o 
                                     ⁢ 
                                     r 
                                   
                                 
                               
                               + 
                             
                           
                         
                         
                           
                             
                               Impedance 
                               
                                 T 
                                 ⁢ 
                                 i 
                                 ⁢ 
                                 s 
                                 ⁢ 
                                 s 
                                 ⁢ 
                                 u 
                                 ⁢ 
                                 e 
                               
                             
                           
                         
                       
                       
                         Impedance 
                         
                           T 
                           ⁢ 
                           i 
                           ⁢ 
                           s 
                           ⁢ 
                           s 
                           ⁢ 
                           u 
                           ⁢ 
                           e 
                         
                       
                     
                   
                   , 
                 
               
               
                 
                   ( 
                   2 
                   ) 
                 
               
             
           
         
       
     
     where Voltage Charge  is the voltage generated from the voltage source  432  and the bulk capacitance  435 , Voltage Pulse  is the pulse_voltage  420 , Impedance Tissue  represents the tissue impedance  440 , and Impedance Generator  is the generator impedance  437 . 
     In some embodiments, a controller (e.g., the controller  120  of  FIG. 1 ) is configured to determine and control the electroporation generator  430  using the equation (2) above. In some embodiments, a controller (e.g., the controller  120  of  FIG. 1 ) is configured to determine and control the electroporation generator  430  using the other approaches to determine the charge_voltage. In some implementations, the electroporation generator  430  is configured to generate an electrical pulse sequence having a plurality of electrical/electroporation pulses (e.g., 2 microseconds electrical pulses with 500 microseconds between two adjacent pulses) during a therapy section (e.g., a therapy section of 10 milliseconds, a therapy section of 20 milliseconds etc.) during a cardiac beat. 
       FIGS. 5A and 5B  are diagrams illustrating example embodiments of catheters  200  and  250  that can be used for electroporation (e.g., catheter  110  in  FIG. 1 ), including ablation by irreversible electroporation, in accordance with embodiments of the subject matter of the disclosure. The catheters  200  and  250  include electrodes, as described below, that are spaced apart from one another and configured to conduct electricity. Catheter characteristics are used to model electric fields that can be produced by the catheter. In embodiments, the characteristics used to model the electric fields can include: the type of catheter, such as a basket catheter that has a constant profile after being opened and a spline catheter that has a variable profile, which can be opened and closed by degree; the form factor of the catheter, such as a balloon catheter, a basket catheter, and a spline catheter; the number of electrodes; the inter-electrode spacing on the catheter; the spatial relationships and orientation of the electrodes, especially in relation to other electrodes on the same catheter; the type of material that the electrodes are made of; and the shape of the electrodes. In embodiments, the type of catheter and/or the form factor of the catheter includes catheters, such as linear ablation catheters and focal ablation catheters. In some cases, the type of catheter and/or the form factor of the catheter is not limited to those mentioned herein. 
       FIG. 5A  is a diagram illustrating the catheter  200 , in accordance with embodiments of the subject matter of the disclosure. The catheter  200  includes a catheter shaft  202  and a catheter basket  204  connected to the catheter shaft  202  at the distal end  206  of the catheter shaft  202 . The catheter basket  204  includes a first group of electrodes  208  disposed at the circumference of the catheter basket  204  and a second group of electrodes  210  disposed adjacent the distal end  212  of the catheter basket  204 . Each of the electrodes in the first group of electrodes  208  and each of the electrodes in the second group of electrodes  210  is configured to conduct electricity and to be operably connected to a controller (e.g., the controller  120  in  FIG. 1 ) and an ablative energy generator (e.g., the electroporation generator  140  of  FIG. 1 ). In embodiments, one or more of the electrodes in the first group of electrodes  208  and the second group of electrodes  210  includes metal. 
     Electrodes in the first group of electrodes  208  are spaced apart from electrodes in the second group of electrodes  210 . The first group of electrodes  208  includes electrodes  208   a - 208   f  and the second group of electrodes  210  includes electrodes  210   a - 210   f . Also, electrodes in the first group of electrodes  208 , such as electrodes  208   a - 208   f , are spaced apart from one another and electrodes in the second of electrodes  210 , such as electrodes  210   a - 210   f , are spaced apart from one another. 
     The spatial relationships and orientation of the electrodes in the first group of electrodes  208  and the spatial relationships and orientation of the electrodes in the second group of electrodes  210  in relation to other electrodes on the same catheter  200  is known or can be determined. In embodiments, the spatial relationships and orientation of the electrodes in the first group of electrodes  208  and the spatial relationships and orientation of the electrodes in the second group of electrodes  210  in relation to other electrodes on the same catheter  200  is constant, once the catheter is deployed. 
     As to electric fields, in embodiments, each of the electrodes in the first group of electrodes  208  and each of the electrodes in the second group of electrodes  210  can be selected to be an anode or a cathode, such that electric fields can be set up between any two or more of the electrodes in the first and second groups of electrodes  208  and  210 . Also, in embodiments, each of the electrodes in the first group of electrodes  208  and each of the electrodes in the second group of electrodes  210  can be selected to be a biphasic pole, such that the electrodes switch or take turns between being an anode and a cathode. Also, in embodiments, groups of the electrodes in the first group of electrodes  208  and groups of the electrodes in the second group of electrodes  210  can be selected to be an anode or a cathode or a biphasic pole, such that electric fields can be set up between any two or more groups of the electrodes in the first and second groups of electrodes  208  and  210 . 
     In embodiments, electrodes in the first group of electrodes  208  and the second group of electrodes  210  can be selected to be biphasic pole electrodes, such that during a pulse train including a biphasic pulse train, the selected electrodes switch or take turns between being an anode and a cathode, and the electrodes are not relegated to monophasic delivery where one is always an anode and another is always a cathode. In some cases, the electrodes in the first and second group of electrodes  208  and  210  can form electric fields with electrode(s) of another catheter. In such cases, the electrodes in the first and second group of electrodes  208  and  210  can be anodes of the fields, or cathodes of the fields. 
     Further, as described herein, the electrodes are selected to be one of an anode and a cathode, however, it is to be understood without stating it that throughout this disclosure the electrodes can be selected to be biphasic poles, such that they switch or take turns between being anodes and cathodes. In some cases, one or more of the electrodes in the first group of electrodes  208  are selected to be cathodes and one or more of the electrodes in the second group of electrodes  210  are selected to be anodes. Also, in embodiments, one or more of the electrodes in the first group of electrodes  208  can be selected as a cathode and another one or more of the electrodes in the first group of electrodes  208  can be selected as an anode. In embodiments, one or more of the electrodes in the second group of electrodes  210  can be selected as a cathode and another one or more of the electrodes in the second group of electrodes  210  can be selected as an anode. 
       FIG. 5B  is a diagram illustrating the catheter  250 , in accordance with embodiments of the subject matter of the disclosure. The catheter  250  includes a catheter shaft  252  and catheter splines  254  connected to the catheter shaft  252  at the distal end  256  of the catheter shaft  252 . The catheter splines  254  includes a first group of electrodes  258  disposed proximal the maximum circumference of the catheter splines  254  and a second group of electrodes  260  disposed distal the maximum circumference of the catheter splines  254 . Each of the electrodes in the first group of electrodes  258  and each of the electrodes in the second group of electrodes  260  is configured to conduct electricity and to be operably connected to the electroporation console (not shown). In embodiments, one or more of the electrodes in the first group of electrodes  258  and the second group of electrodes  260  includes metal. 
     Electrodes in the first group of electrodes  258  are spaced apart from electrodes in the second group of electrodes  260 . The first group of electrodes  258  includes electrodes  258   a - 258   f  and the second group of electrodes  260  includes electrodes  260   a - 260   f . Also, electrodes in the first group of electrodes  258 , such as electrodes  258   a - 258   f , are spaced apart from one another and electrodes in the second of electrodes  260 , such as electrodes  260   a - 260   f , are spaced apart from one another. 
     The spatial relationships and orientation of the electrodes in the first group of electrodes  258  and the spatial relationships and orientation of the electrodes in the second group of electrodes  260  in relation to other electrodes on the same catheter  250  are known or can be determined. In embodiments, the spatial relationships and orientation of the electrodes in the first group of electrodes  258  and the spatial relationships and orientation of the electrodes in the second group of electrodes  260  in relation to other electrodes on the same catheter  250  are variable, where the distal end  262  of the catheter  250  can be extended and retracted which changes the spatial relationships and orientation of the electrodes  258  and  260 . In some embodiments, the spatial relationships and orientation of the electrodes in the first group of electrodes  258  and the spatial relationships and orientation of the electrodes in the second group of electrodes  260  on the same catheter  250  is constant, once the catheter  250  is deployed. 
     As to electric fields, in embodiments, each of the electrodes in the first group of electrodes  258  and each of the electrodes in the second group of electrodes  260  can be selected to be an anode or a cathode, such that electric fields can be set up between any two or more of the electrodes in the first and second groups of electrodes  258  and  260 . Also, in embodiments, groups of the electrodes in the first group of electrodes  258  and groups of the electrodes in the second group of electrodes  260  can be selected to be an anode or a cathode, such that electric fields can be set up between any two or more groups of the electrodes in the first and second groups of electrodes  258  and  260 . In some cases, the electrodes in the first and second group of electrodes  258  and  260  can form electric fields with electrode(s) of another catheter. In such cases, the electrodes in the first and second group of electrodes  258  and  260  can be anodes of the fields, or cathodes of the fields. 
     In some embodiments, one or more of the electrodes in the first group of electrodes  258  are selected to be cathodes and one or more of the electrodes in the second group of electrodes  260  are selected to be anodes. Also, in embodiments, one or more of the electrodes in the first group of electrodes  258  can be selected as a cathode and another one or more of the electrodes in the first group of electrodes  258  can be selected as an anode. In addition, in embodiments, one or more of the electrodes in the second group of electrodes  260  can be selected as a cathode and another one or more of the electrodes in the second group of electrodes  260  can be selected as an anode. Using the characteristics of the catheter  250  and the surrounding tissue, an electroporation controller (e.g., the controller  120  of  FIG. 1 ) can determine models for the various electric fields that can be produced by the catheter  250 . 
       FIG. 6  is an example flow diagram depicting an illustrative method  600  of using an electroporation ablation device, in accordance with some embodiments of the present disclosure. Aspects of embodiments of the method  600  may be performed, for example, by an electroporation ablation system (e.g., the system  100  depicted in  FIG. 1 ). One or more steps of method  600  are optional and/or can be modified by one or more steps of other embodiments described herein. Additionally, one or more steps of other embodiments described herein may be added to the method  600 . First, the electroporation ablation system deploys the electroporation ablation catheter(s) proximate to target tissues ( 605 ). 
     In some cases, the electroporation ablation system is configured to conduct a scan section to determine an initial tissue impedance ( 610 ). In some cases, the scan section is conducted before therapy sections. In some cases, the scan section includes a scan electrical pulse sequence at a scan voltage lower than the therapeutic pulse voltage. In one embodiment, the scan electrical pulse sequence includes a single non-ablative electrical pulse during the scan section. In some embodiments, the initial pulse voltage of the scan electrical pulse sequence and the initial pulse current of the scan electrical pulse sequence are measured during the scan section. In some cases, the initial pulse voltage and the initial pulse current are measured for a last electrical pulse in the scan electrical pulse sequence. In some cases, the initial pulse voltage and/or initial first pulse current is measured for a first electrical pulse of the scan electrical pulse sequence. In some cases, the initial pulse voltage and/or the initial pulse current are determined based on measurements of a plurality of electrical pulses in the scan electrical pulse sequence. 
     In one example, the initial pulse voltage and/or the initial pulse current are an average voltage and/or current measured for a plurality of electrical pulses in the scan section respectively. In one example, the initial pulse voltage and/or the initial pulse current are an average voltage and/or current measured for all the electrical pulses in the scan section respectively. In some embodiments, the initial tissue impedance is determined to be the initial pulse voltage divided by the initial pulse current. In some cases, the generator impedance can be determined by the charge voltage output from the capacitor bank (e.g., capacitor bank  145  of  FIG. 1 ) and the measured pulse voltage, for example, using equation (1). 
     In some embodiments, the electroporation ablation system is configured to measure one or more pulse voltages ( 615 ), for example, during a therapy section. In some embodiments, the electroporation ablation system is configured to measure one or more pulse currents ( 620 ), for example, corresponding to the one or more pulse voltages. In some cases, a controller (e.g., the controller  120  in  FIG. 1 ) of the electroporation ablation system is configured to determine a current tissue impedance using the one or more measured pulse voltages and/or the one or more measured pulse currents. In one implementation, the current tissue impedance is determined to be the pulse voltage divided by the pulse current. In one implementation, the current tissue impedance is determined to be the pulse voltage divided by the pulse current measured at the first electrical pulse during the therapy section. 
     In one implementation, the current tissue impedance is determined to be the pulse voltage divided by the pulse current measured at the last electrical pulse during the therapy section. In one implementation, the current tissue impedance is determined to be the pulse voltage divided by the pulse current. In one implementation, the current tissue impedance is determined based on a plurality of pulse voltages and a plurality of pulse currents measured during the therapy section. In some cases, the current tissue impedance is used to determine the charge voltage of the electroporation generator (i.e. the voltage generated by the electroporation generator). In some cases, the pulse voltage and/or pulse current are measured by sensors (e.g., sensors  130  in  FIG. 1 ) deployed proximate to the target tissues. In some cases, the pulse voltage and/or pulse current are measured by sensors deployed with the catheter(s). 
     In some embodiments, the electroporation ablation system is configured to determine a charge voltage of the electroporation generator (e.g., electroporation generator  140  in  FIG. 4 ) ( 625 ). In one example, the charge voltage is computed using equation (2). For example, if the measured pulse voltage of a prior therapy section is low by 100 volts from the target pulse voltage and assuming the generator impedance equal to the tissue impedance, the charge voltage is to be increased by 200 volts. In one implementation, the electroporation ablation system can set the capacitor bank (e.g., capacitor bank  145  in  FIG. 4 ) with a 200-volt increase in the setting, such that the electrical pulse sequence is delivered at a voltage close to the target pulse voltage in the next therapy section. 
     In one embodiment, the electric field generated by electrodes of the deployed catheter(s) has a field strength no higher than 1500 volts per centimeter. In one embodiment, the electric field generated by electrodes of the deployed catheter(s) has a field strength higher than 500 volts per centimeter. In some embodiments, the electroporation ablation system is configured to control the power source based on the determined charge voltage ( 630 ), for example, by charging the capacitor bank based on the determined charge voltage. In some embodiments, the electroporation ablation system is configured to set the capacitor bank based on a voltage difference between the determined charge voltage and the current charge voltage of the power source. 
     In some embodiments, the electroporation ablation system is configured to deliver an electrical pulse sequence ( 635 ) for a next therapy section, for example, using the power source. In some cases, if the ablation therapy section has not ended, the electroporation ablation system goes back to step  615  to measure the one or more pulse voltages during the electrical pulse sequence (e.g., a plurality of electrical pulses delivered during a burst period) being delivered. In embodiments, the electroporation ablation system configured to measure pulse voltages and/or pulse currents during each or some of the therapy sections to determine the charge voltages for the subsequent therapy sections. 
     Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the present disclosure. For example, while the embodiments described above refer to particular features, the scope of the present disclosure also includes embodiments having different combinations of features and embodiments that do not include all of the described features. Accordingly, the scope of the present invention is intended to embrace all such alternatives, modifications, and variations as fall within the scope of the claims, together with all equivalents thereof.