Electrode edge transition for improved current density

Abstract

A catheter for ablating tissue by irreversible electroporation is disclosed. The catheter includes an elongate body having a proximal end and a distal end. The catheter also includes a first electrode disposed proximally spaced along the elongate body from the second electrode, each of the first and second electrodes having a transition region terminating at opposing edges. The catheter also includes an insulator disposed over the electrode in the transition region and extending between the first electrode and the second electrode. In the transition region, the electrode thickness of each electrode decreases toward the opposite edge, and the insulator thickness of the insulator correspondingly increases to maintain a substantially constant combined thickness.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Application No. 63 / 447,608, filed on February 22, 2023, entitled “ELECTRODE EDGE TRANSITION TO IMPROVE CURRENT DENSITY.” Technical Field

[0003] The present disclosure relates to medical systems and methods for ablating tissue within a patient. More particularly, the present disclosure relates to medical systems and methods for ablating tissue by electroporation. Background Art

[0004] Ablation procedures are used to treat many different conditions in patients. Ablation can be used to treat arrhythmias, benign tumors, cancerous tumors, and to control bleeding during surgery. Typically, ablation is performed using thermal ablation techniques, including radiofrequency (RF) ablation and cryoablation. In RF ablation, a probe is inserted into the patient's body, and radiofrequency waves are transmitted through the probe to the surrounding tissue. The radiofrequency waves generate heat, which destroys the surrounding tissue and burns blood vessels. In cryoablation, a hollow needle or cryoprobe is inserted into the patient's body, and a cold, heat-conducting fluid is circulated through the probe to freeze and kill the surrounding tissue. RF ablation and cryoablation techniques kill tissue indiscriminately by causing cell necrosis, which may damage or kill other healthy tissue, such as esophageal tissue, phrenic nerve cells, and coronary artery tissue.

[0005] Another ablation technique uses electroporation. In electroporation, or electroosmosis, an electric field is applied to cells to increase the permeability of the cell membrane. Electroporation can be reversible or irreversible, depending on the strength of the electric field. If electroporation is reversible, the increased permeability of the cell membrane can be used to introduce chemicals, drugs, and / or deoxyribonucleic acid (DNA) into the cells before the cells heal and recover. If electroporation is irreversible, the affected cells are killed by apoptosis.

[0006] Irreversible electroporation can be used as a non-thermal ablation technique. In irreversible electroporation, a series of short, high-voltage pulses are used to generate an electric field strong enough to kill cells by apoptosis. In the ablation of cardiac tissue, irreversible electroporation can serve as a safe and effective alternative to indiscriminate thermal ablation techniques (such as radiofrequency ablation and cryoablation). Irreversible electroporation can kill targeted tissue, such as myocardial tissue, by using an electric field strength and duration that kills the targeted tissue but does not permanently damage other cells or tissues (such as non-targeted myocardial tissue, red blood cells, vascular smooth muscle tissue, endothelial tissue, and nerve cells). There is a continuing need for improved devices and methods for performing cardiac tissue ablation by irreversible electroporation. SUMMARY

[0007] In Example 1, a catheter for ablating tissue by irreversible electroporation includes an elongated body having a proximal end and a distal end. The catheter further includes a first electrode spaced proximally along the elongated body from a second electrode, each of the first and second electrodes having a transition region terminating in an opposing edge. The catheter further includes an insulator disposed over the electrodes in the transition region and extending between the first and second electrodes; wherein in the transition region, an electrode thickness of each electrode decreases toward the opposing edge and an insulator thickness of the insulator correspondingly increases to maintain a substantially constant combined thickness.

[0008] Example 2 is the catheter of Example 1, wherein each transition region has a substantially similar shape.

[0009] Example 3 is the catheter of Example 1, wherein each transition region is configured such that a current density in the transition region is substantially constant when a voltage is applied to each electrode.

[0010] Example 4 is the catheter of Example 1, wherein each electrode has a constant taper angle in the transition region.

[0011] Example 5 is the catheter of Example 1, wherein the insulator portion includes a dielectric strength from about 15 kV / mm to 60 kV / mm.

[0012] Example 6 is the catheter of Example 5, wherein the dielectric strength of the insulator determines a gradient of the current density.

[0013] Example 7 is the catheter of Example 1, wherein the transition region condition is formed by a tapered insulator over the electrodes to create a gradual transition current density from an insulator preform to the electrodes, thereby reducing the transition current density.

[0014] Example 8 is the catheter of Example 1, wherein the transition region includes one or more steps, ramps, or a combination of various geometric shaped transitions.

[0015] Example 9 is the catheter of Example 1, further including a third electrode and a fourth electrode, each of the third and fourth electrodes having a decreasing diameter in the transition region toward the opposing edge, and the insulator having a correspondingly increasing diameter such that a catheter shaft is substantially constant diameter.

[0016] Example 10 is the catheter of Example 1, wherein the elongated body includes a tubular shaft having a proximal end and an opposing distal end.

[0017] Example 11 is a catheter according to example 10, wherein the slender body further comprises a plurality of prongs, each prong comprising a distal portion coupled to the central hub and a proximal portion coupled to the tubular shaft.

[0018] Example 12 is the catheter of example 11, wherein the first electrode and the second electrode are disposed on one of the plurality of prongs.

[0019] Example 13 is a catheter according to Example 11, wherein the electrode assembly further comprises a plurality of proximal ablation electrodes located on each branch.

[0020] Example 14 is a catheter according to Example 10, wherein the first electrode and the second electrode are disposed on the tubular shaft.

[0021] Example 15 is a catheter according to example 10, wherein the cone angle of each of the electrodes in the transition region is between about 20 and about 60 degrees.

[0022] In Example 16, a catheter for ablation of tissue by irreversible electroporation includes an elongated body extending along a longitudinal axis and having a proximal end and a distal end. The catheter also includes a first electrode spaced proximally from a second electrode along the elongated body, each of the first electrode and the second electrode having a transition region terminating at opposing edges. The catheter also includes an insulator disposed above the electrodes in the transition region and extending between the first electrode and the second electrode; wherein, in the transition region, the electrode thickness of each electrode decreases toward the opposing edges, and the insulator thickness of the insulator correspondingly increases to maintain a substantially constant combined thickness.

[0023] Example 17 is a catheter according to example 16, wherein each transition region has a substantially similar shape.

[0024] Example 18 is a catheter according to Example 16, wherein each transition region is configured such that when a voltage is applied to each electrode, a current density in the transition region is substantially constant.

[0025] Example 19 is a catheter according to Example 18, wherein each electrode has a constant cone angle in the transition region.

[0026] Example 20 is a catheter according to Example 16, wherein the insulator portion comprises a dielectric strength of approximately from 15 kV / mm to 60 kV / mm.

[0027] Example 21 is a catheter according to Example 20, wherein the dielectric strength of the insulation determines the gradient of the current density.

[0028] Example 22 is a catheter according to Example 16, wherein the transition region condition is formed by tapered insulation on the electrode, thereby creating a gradual transition current density from the insulation preform to the electrode to reduce the transition current density.

[0029] Example 23 is a catheter according to Example 16, wherein the transition region includes one or more steps, ramps, or a combination of transitions of various geometries.

[0030] Example 24 is a catheter according to Example 16, further comprising a third electrode and a fourth electrode and an insulator, wherein the diameter of each of the third electrode and the fourth electrode decreases toward the relative edge in the transition region and the diameter of the insulator increases accordingly, so that the catheter shaft is substantially isodiametric.

[0031] In Example 25, a catheter for ablating cardiac tissue by irreversible electroporation includes an elongated shaft extending along a longitudinal axis and having a proximal end and a distal end. The catheter also includes a tip electrode located at the distal end of the elongated shaft and configured to provide a pulsed field ablation signal. The catheter also includes a ring electrode located proximal to and spaced apart from the tip electrode, the first ring electrode having a distal portion. The catheter also includes an insulator disposed between the tip electrode and the first ring electrode; wherein the distal portion of the ring electrode is tapered in a distal direction along the longitudinal axis in a transition region such that the electrode thickness of the electrode decreases and the insulator thickness of the insulator increases to maintain a substantially uniform catheter diameter.

[0032] Example 26 is a catheter according to Example 25, wherein the tip electrode is tapered in a distal direction along the longitudinal axis in a transition region such that the electrode thickness decreases and the insulator thickness increases to maintain a generally uniform catheter diameter.

[0033] Example 27 is a catheter according to Example 25, wherein each transition region has a substantially similar shape.

[0034] Example 28 is a catheter according to example 25, wherein each transition region is configured such that when a voltage is applied to each pole, a current density in the transition region is substantially constant.

[0035] Example 29 is a catheter according to Example 28, wherein each electrode has a constant cone angle in the transition region.

[0036] Example 30 is a catheter according to Example 25, wherein the insulator portion comprises a dielectric strength of approximately from 15 kV / mm to 60 kV / mm.

[0037] Example 31 is a catheter according to Example 30, wherein the dielectric strength of the insulation determines the gradient of the current density.

[0038] Example 32 is a catheter according to Example 25, wherein the transition region condition is formed by tapered insulation on the electrode to create a gradual transition current density from the insulation preform to the electrode, thereby reducing the transition current density.

[0039] Example 33 is a catheter according to Example 25, wherein the transition region includes one or more steps, ramps, or a combination of transitions of various geometries.

[0040] Example 34 is a catheter according to Example 25, wherein the slender shaft further includes a third electrode and a fourth electrode and an insulator, wherein the third electrode is tapered in a distal direction along the longitudinal axis in a transition region such that the electrode thickness decreases and the insulator thickness increases to maintain a substantially uniform catheter diameter.

[0041] Example 35 is a method of manufacturing a catheter for ablating cardiac tissue by irreversible electroporation, the method comprising providing an elongated shaft extending along a longitudinal axis and having a proximal end and a distal end. The method further comprises securing a first electrode spaced apart from a second electrode along the elongated shaft, each of the electrodes having a transition region terminating at opposing edges. The method further comprises securing an insulator disposed above the electrode in the transition region and extending between the first electrode and the second electrode, wherein a diameter of each of the first electrode and the second electrode decreases in the transition region toward the opposing edges, and a diameter of the insulator correspondingly increases, such that the catheter shaft is substantially isodiametric.

[0042] Although multiple embodiments are disclosed, other embodiments of the present disclosure will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the present disclosure. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a diagram illustrating an exemplary clinical apparatus for treating a patient using an electrophysiology system and treating the patient's heart, according to an embodiment of the disclosed subject matter.

[0044] Figure 2 According to an embodiment of the present disclosure, Figure 1 Isometric view of the distal portion of a cardiac ablation catheter of an electrophysiology system.

[0045] Figure 3 According to an embodiment of the present disclosure, Figure 1 Isometric view of the distal portion of the branch catheter of the electrophysiology system.

[0046] Figure 4A and Figure 4BShown are the current densities generated near the edges of the ablation electrodes of a conventional pulsed field ablation catheter compared to an enhanced edge transition pulsed field ablation catheter during operation.

[0047] 5A to 5D Exemplary electrode edge transition stages are shown according to an embodiment of the disclosed subject matter.

[0048] While the present disclosure is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and described in detail below. However, it is not intended to limit the present disclosure to the particular embodiments described. On the contrary, the present disclosure is intended to cover all modifications, equivalents, and alternatives falling within the scope of the present disclosure as defined by the appended claims. DETAILED DESCRIPTION

[0049] To promote an understanding of the principles of the present disclosure, reference is now made to the examples shown in the accompanying drawings, which will be described below. The illustrated examples disclosed herein are not intended to be exhaustive or to limit the disclosure to the precise forms disclosed in the following detailed description. On the contrary, these exemplary embodiments are selected and described so that others skilled in the art can use their teachings. It is not beyond the scope of this disclosure to use multiple (e.g., all) features in a given example in all examples. Therefore, any figure should not be interpreted as having any dependency or requirement on any single component or combination of components shown therein. In addition, in the examples, the various components depicted in a given figure can be integrated with various components (and / or components not shown) in other components depicted therein, all of which are considered to be within the scope of this disclosure.

[0050] The terms "coupled," "coupled," "connected," "attached," and the like, and variations thereof, are intended to encompass both arrangements in which two or more components are in direct physical contact, and arrangements in which two or more components are not in direct contact with each other but still cooperate or interact with each other (e.g., the components are "coupled" via at least a third component).

[0051] Throughout this disclosure and in the claims, numerical terms (such as first and second) are used to refer to various components or features. Such usage does not imply an order for the components or features. Instead, the numerical terms are used to help the reader identify the referenced components or features and should not be narrowly interpreted as providing a specific order for the components or features.

[0052] Figure 1is a diagram illustrating an exemplary clinical apparatus 10 for treating a patient 20 and treating a heart 30 of the patient 20 using an electrophysiology system 50 in accordance with an embodiment of the presently disclosed subject matter. The electrophysiology system 50 includes an electroporation device 60 and an optional localization field generator 80. In addition, the clinical apparatus 10 includes additional equipment, such as imaging equipment 94 (represented by a C-arm) and various controller elements configured to allow an operator to control various aspects of the electrophysiology system 50. As will be appreciated by those skilled in the art, the clinical apparatus 10 may have Figure 1 Other components and arrangements of components not shown.

[0053] The electroporation device 60 includes a cardiac ablation catheter 105, an introducer sheath 110, a controller 90, and an electroporation generator 130. In embodiments, the electroporation device 60 is configured to deliver electric field energy to targeted tissue in the patient's heart 30 to induce tissue apoptosis, rendering the tissue unable to conduct electrical signals. The controller 90 is configured to control functional aspects of the electroporation device 60. In embodiments, the controller 90 is configured to control the electroporation generator 130 to generate electrical pulses, such as the amplitude, timing, and duration of the electrical pulses. In embodiments, the electroporation generator 130 can operate as a pulse generator for generating and supplying pulse sequences to the cardiac ablation catheter 105.

[0054] In embodiments, the introducer sheath 110 is operable to provide a delivery conduit through which the cardiac ablation catheter 105 can be deployed to a specific target site within the patient's heart 30. However, it should be understood that the introducer sheath 110 is shown and described herein to provide context for the overall electrophysiology system 50.

[0055] In the illustrated embodiment, the cardiac ablation catheter 105 includes a handle 105a, an elongated shaft 105b, and a distal portion 150. As shown, the shaft has a distal end 105c and a proximal end 105d, with the proximal end 105d of the shaft 105b extending distally from the handle 105a. The handle 105a is configured to be manipulated by a user to position the distal portion 150 at a desired anatomical location. The shaft 105b generally defines the longitudinal axis of the cardiac ablation catheter 105. The shaft 105b may include molded joints for spinal reinforcement and steerability. Further details can be found in U.S. patent application 63 / 129,960, the entire contents of which are incorporated herein by reference.

[0056] As shown, distal portion 150 is located at or near distal end 105c of shaft 105b. In embodiments, distal portion 150 is electrically coupled to electroporation generator 130 to receive a sequence or train of electrical pulses to selectively generate an electric field for ablating targeted tissue by irreversible electroporation.

[0057] In some embodiments, the cardiac ablation catheter 105 is a pointed catheter comprising a linear body toward the distal end. In an embodiment, the distal portion 150 comprises one or more electrodes disposed on the shaft 105b. In some embodiments, the distal portion 150 comprises one or more electrode pairs. In some embodiments, the distal portion 150 comprises one or more ablation electrodes and one or more sensing electrodes. In some embodiments, the distal portion 150 comprises a pair of ablation electrodes configured to generate an electric field sufficient for irreversible electroporation ablation. In some examples, the ablation electrode pair comprises a tip electrode covering the distal end of the catheter 105 and a ring electrode disposed proximate to the tip electrode. As used herein, a ring electrode refers to an electrode having a ring shape. In some designs, the pair of ablation electrodes comprises two ring electrodes disposed proximate to the distal end of the catheter 105.

[0058] In an embodiment, the electrode positions and sizes are specifically designed to allow flexibility. For example, the electrodes are designed to be relatively short in length. As another example, two electrodes have a relatively large spacing to achieve flexibility and / or deflection. In some examples, one or more electrodes include one or more pairs of ablation electrodes and one or more pairs of sensing electrodes. The sensing electrodes can be used to sense electrical signals associated with the patient's heart, which allows an operator or system to determine whether ablation has occurred. In some designs, the electrical signals can be used to determine the position or approximate position of the cardiac ablation catheter 105. In some embodiments, other sensors (such as force sensors, navigation sensors (e.g., five degrees of freedom or six degrees of freedom ("DoF") sensors)) can be incorporated into the distal portion 150.

[0059] In some embodiments, one or more sensing electrodes on the cardiac ablation catheter 105 can measure electrical signals and generate output signals that can be processed by a controller (e.g., controller 90) to generate an electroanatomical map. In some cases, the electroanatomical map is generated before ablation to determine the electrical activity of cardiac tissue within the chamber of interest. In some cases, the electroanatomical map is generated after ablation to verify the desired changes in the electrical activity of the ablated tissue and the chamber as a whole. The sensing electrodes can be used to determine the position of the catheter 105 in three-dimensional space within the body. For example, as the operator moves the catheter 105 within the patient's cardiac cavity, the boundaries of the catheter movement can be determined by the controller 90, which can include or be coupled to a mapping and navigation system to form the anatomical structure of the chamber. The chamber anatomy can be used to facilitate navigation of the catheter 105 without the use of ionizing radiation (such as fluoroscopy) and to mark the location of the ablation when the ablation is completed to guide the ablation spacing and help the operator completely ablate the anatomical structure of interest.

[0060] According to embodiments, various components of the electrophysiology system 50 (e.g., the controller 90) can be implemented on one or more computing devices. The computing devices can include any type of computing device suitable for implementing embodiments of the present disclosure. Examples of computing devices include special-purpose computing devices or general-purpose computing devices such as workstations, servers, laptops, portable devices, desktop computers, tablet computers, hand-held devices, general-purpose graphics processing units (GPGPUs), and the like, all within the scope of the present disclosure. Figure 1 Various components of the system 50 are contemplated with reference to the various components of the system 50.

[0061] In some embodiments, the computing device includes a bus that directly and / or indirectly couples the following devices: the processor, the memory, input / output (I / O) ports, I / O components, and a power supply. Any number of additional components, different components, and / or combinations of components can also be included in the computing device. The bus represents what can be one or more busses, such as, for example, an address bus, a data bus, or a combination thereof. Similarly, in some embodiments, the computing device can include a plurality of processors, a plurality of memory components, a plurality of I / O ports, a plurality of I / O components, and / or a plurality of power supplies. Moreover, any number and combination of these components or combinations thereof can be distributed and / or duplicated on a plurality of computing devices.

[0062] In some embodiments, the system 50 includes one or more memories (not shown). The one or more memories include computer-readable media in the form of volatile and / or nonvolatile memory, transitory and / or non-transitory storage media, and can be removable, non-removable, or a combination thereof. Media examples include random access memory (RAM); read-only memory (ROM); electrically erasable programmable read-only memory (EEPROM); flash memory; optical or holographic media; magnetic tape, magnetic-based or other disk storage, or other magnetic storage devices; data transmission; and / or any other media that can be used to store information and that can be accessed by a computing device, such as quantum state memories and / or the like. In some embodiments, the one or more memories store computer-executable instructions for causing a processor (e.g., the controller 90) to implement aspects of embodiments of the system components discussed herein and / or to perform aspects of embodiments of the methods and procedures discussed herein.

[0063] The computer-executable instructions can include, for example, computer code, machine-useable instructions, and / or the like, such as, for example, program components that are executable by one or more processors associated with a computing device. The program components can be programmed using any number of different programming environments, including various languages, development toolkits, frameworks, and / or the like. Some or all of the functionality contemplated herein can also or alternatively be implemented in hardware and / or firmware.

[0064] In some embodiments, the memory may include a data repository implemented using any of the configurations described below. The data repository may include random access memory, flat files, XML files, and / or one or more database management systems (DBMS) executed on one or more database servers or data centers. The database management system may be a relational (RDBMS), hierarchical (HDBMS), multidimensional (MDBMS), object-oriented (ODBMS or OODBMS), or object-relational (ORDBMS) database management system, etc. The data repository may be, for example, a single relational database. In some cases, the data repository may include multiple databases that can exchange and aggregate data through a data integration process or software application. In an exemplary embodiment, at least a portion of the data repository may be hosted in a cloud data center. In some cases, the data repository may be hosted on a single computer, server, storage device, cloud server, etc. In some other cases, the data repository may be hosted on a series of networked computers, servers, or devices. In some cases, the data repository may be hosted on various layers of data storage devices, including local, regional, and central.

[0065] The various components of the system 50 can communicate or be coupled to a communication interface via a communication interface, for example, a wired or wireless interface. The communication interface includes, but is not limited to, any short-range and long-range communication interface, whether wired or wireless. The wired interface can use a cable, an umbilical cable, etc. The short-range communication interface can be, for example, a local area network (LAN), an interface that conforms to a known communication standard, such as Standards, IEEE 702 standards (such as IEEE 702.11), or similar specifications, such as those based on the IEEE 702.15.4 standard, or other public or proprietary wireless protocols. The remote communication interface can be, for example, a wide area network (WAN), a cellular network interface, a satellite communication interface, etc. The communication interface can be located within a private computer network, such as an intranet, or on a public computer network, such as the Internet.

[0066] As will be explained in greater detail elsewhere herein, various embodiments of the present disclosure, and in particular the distal portion 150, employ novel structural features to improve clinical performance and enhance the manufacturability of the ablation catheter 105. In particular, the distal portion 150 includes an insulator portion to, among other things, support and position the tip electrode and adjacent ring electrodes, as well as operate to electrically insulate various electrical components of the distal portion 150.

[0067] Figure 2 is an isometric view of the distal portion of the cardiac ablation catheter 200. In an embodiment, the cardiac ablation catheter 200 corresponds to Figure 1The ablation catheter 105 depicted in , and includes a distal portion 202.

[0068] As shown, the distal portion 202 is arranged along the axis ( Figure 2 204 is axially arranged about a longitudinal axis 204 defined by the distal portion 202 (not shown). The distal portion 202 includes a pair of electrodes 208, the pair of electrodes 208 including a tip electrode 212 and a ring electrode 214, the tip electrode 212 being located at the distal end of the distal portion 202, and the ring electrode 214 being located proximal to and spaced apart from the tip electrode 212. As shown, the ring electrode has a distal leading end 214a and a proximal trailing end 214b. In embodiments, the distal portion 202 may include additional electrodes, for example, an additional pair of electrodes 210 including electrodes 216, 218 disposed proximal to and longitudinally spaced apart from the electrodes 212 and 214. More or fewer electrodes may be employed in other embodiments within the scope of the present disclosure.

[0069] The operation of the various electrodes (or electrode pairs) can vary depending on the clinical use of the ablation catheter 200. In various embodiments, the electrodes 212, 214, 216 and 218 are configured to operate as ablation electrodes, sensing electrodes, or both. For example, any one or all of the electrodes 212, 214, 216 and 218 can be configured to be operable to deliver ablation energy to the target tissue. Additionally or alternatively, any one or all of the electrodes 212, 214, 216 and 218 can operate as sensing electrodes that are configured to sense electrical signals (e.g., intracardiac activation signals and / or electric fields generated by injected currents for impedance-based position tracking, tissue proximity or contact sensing, etc.). In one embodiment, the pair of electrodes 208 can be configured to operate as ablation electrodes, for example, for bipolar delivery of ablation energy, and in particular, pulsed field ablation energy for focal ablation of cardiac tissue. In an embodiment, the electrodes 216, 218 can operate as sensing electrodes or alternatively as ablation electrodes. In some cases, the second pair of electrodes 210 is configured to measure local impedance and can act as a position sensor for sensing the local electric field in five degrees of freedom (e.g., five different motions - x, y, z, acceleration, and rotation). In embodiments, except as specifically described herein, the electrodes 212, 214, 216, and 218 can be configured according to those described in co-pending and commonly assigned U.S. patent application 63 / 194,716, the entire contents of which are incorporated herein by reference.

[0070] In an exemplary embodiment, the electrode pair 208 may be activated with a first polarity and the electrode pair 210 may be activated with a second polarity opposite to the first polarity to define an ablation vector and a corresponding electric field therebetween. However, it is emphasized that the present disclosure is not limited to Figure 2 Rather, those skilled in the art will appreciate that additional variations in electrode configurations, number of electrodes, etc., may be employed within the scope of the present disclosure.

[0071] In an embodiment, as shown, the distal portion 202 includes an insulator portion 220 positioned between the tip electrode 212 and the ring electrode 214. In the illustrated embodiment, the insulator portion 220 includes a distal portion 220a and a proximal portion 220b ( Figure 2 ). As further shown, a distal portion 220a of the insulator portion 220 is disposed between the tip electrode 212 and the ring electrode 214, and the ring electrode 214 is disposed over a portion of the proximal portion 220b such that a distal leading end 214a of the ring electrode 214 abuts a radial shoulder of the insulator portion 220. The insulator portion 220 includes a longitudinal spacing along the longitudinal axis 204 between the tip electrode 212 and the distal leading end 214a of the ring electrode 214. In embodiments, the insulator portion 220 provides an insulating layer between conductive surfaces within the tip region of the catheter and the high potential conductor.

[0072] In some cases, the insulator portion provides a means for routing the conductive wire 226 through the distal portion 202. In some cases, the insulator portion provides a positive placement feature for the tip component to enable better component spacing and assembly (i.e., mold assembly) in subsequent process steps. In some cases, the insulator portion provides protection for components of the cardiac ablation catheter 200 (such as navigation sensors or thermocouples) during various conditions of use.

[0073] In various embodiments, the distal portion 202 also includes an insulating material 230 that is disposed at least proximal to the ring electrode 214 and encapsulates and forms an outer insulating surface of the distal portion 202. In embodiments, the insulating material 230 is disposed between the ring electrodes 214 and 216. In some embodiments, the insulating material 230 is formed by an overmolding process. Alternatively, the insulating material 230 can be formed using a reflow process, in which one or more tubular segments of insulating material are disposed around the partially assembled distal portion 202 and then heated, as is known in the art. In other embodiments, the insulating material 230 is pre-molded and preformed. Embodiments that employ an overmolding process to provide the insulating material 230 can have certain advantages, such as reducing or even eliminating the need for subsequent processing (such as injecting a medical adhesive to complete the assembly process and provide a fluid-tight connection between the various components). The insulating material can be commercially available and Both materials can be used in overmolding processes and bonded to “epoxy bondable” wire insulation. Pellethane can be overmolded using a primer (e.g., SivateTM E610) and plasma to adhere to the tip insulator. Pebax can be adhered to the tip insulator without plasma using an adhesive (e.g., Thermedics 1-MP).

[0074] Figure 3 is a partial perspective view illustration of a cardiac ablation catheter 300 having a catheter distal portion 302 according to embodiments of the present disclosure. In embodiments, the cardiac ablation catheter 300 corresponds to the ablation catheter 105 depicted in Figure 1

[0075] As shown, the ablation catheter 300 has a tubular outer shaft 308 having a shaft distal end 309 and an electrode assembly 310 extending distally from the distal end 309 of the outer shaft 308. In embodiments, the electrode assembly 310 is configured to self-expand from a collapsed configuration when constrained within a delivery sheath to a predefined expanded configuration defining an interior space 312. As will be explained in greater detail herein, the electrode assembly 310 includes a plurality of ablation electrodes configured to deliver ablation energy to target tissue from Figure 1 from the electroporation console 130, thereby creating a pulsed electric field sufficient to ablate target tissue via irreversible electroporation. In addition, the electrode assembly 310 also includes a plurality of mapping and sensing electrodes configured for, among other things, sensing cardiac electrical signals, positioning of the electrode assembly 310 within patient anatomy, and determining proximity to targeted tissue within the anatomy.

[0076] In the illustrated embodiment, the electrode assembly 310 includes a distally located central hub portion 314 and a plurality of struts 316A-316F extending proximally from the central hub portion 314. As further shown, each respective strut 316A-316F has a distal end portion 317 and a proximal end portion 318. While in the illustrated embodiment, the distal end portion 317 and the proximal end portion 318 are shown only on the strut 316C, each of the plurality of struts 316A-316F has a distal end portion 317 and a proximal end portion 318. As shown, the proximal end portion 318 is attached to and constrained by the distal end 309 of the outer shaft 302. In embodiments, the particular geometry of the struts 316A-316F and related components (e.g., ablation and mapping electrodes) is optimized to provide the required mechanical and therapeutic / diagnostic capabilities. Figure 3

[0077] ​​In the illustrated embodiment, the legs 316A to 316F are comprised of a support member 320 and a flexible circuit 322 secured to and disposed over an outer surface of the support member 320. The support member 320 serves, among other things, as the primary structural support for the electrode assembly 310 and, therefore, primarily defines the mechanical properties of the electrode assembly 310. In an embodiment, the support member 320 is formed of a superelastic material (metal or polymer) to provide the desired mechanical / structural properties to the electrode assembly 310. In an embodiment, the support member 320 is formed of a superelastic metal alloy (e.g., nickel titanium alloy).

[0078] The support member 320 includes a support member hub 324 and a plurality of support member branches. In embodiments, the support member branches can be selectively configured along their length to adjust the mechanical properties of the electrode assembly 310. As shown, the flexible circuit 322 includes a distal ablation electrode 338. The flexible circuit 322 also includes a plurality of proximal ablation electrodes 344 and a plurality of branch sensing electrodes 350. Although the proximal ablation electrode 344 and the branch sensing electrodes 350 are only shown on branch 316C, each of the plurality of branches 316A to 316F includes a proximal ablation electrode 344 and a plurality of branch sensing electrodes 350. In some embodiments, insulation is used to create a surface that is flush with the surface of the electrode branches. In other embodiments, only a portion of the transition region is covered. In such embodiments, one or more electrodes protrude from the surface of the electrode branches.

[0079] In the illustrated embodiment, each of the prong sensing electrodes 350 is disposed within the periphery of one of the proximal ablation electrodes 244 or within the periphery of one of the radial segments of the distal ablation electrode 338. For example, as shown, each of the distal-most prong sensing electrodes 350 is disposed within the periphery of a corresponding one of the radial segments of the distal ablation electrode 338 and is electrically isolated from the distal ablation electrode 338. Additionally, a plurality of more proximally located prong sensing electrodes 350 are disposed along the periphery of and within each of a corresponding one of the proximal ablation electrodes 344 and are electrically isolated from the proximal ablation electrode 344.

[0080] Figure 4A and Figure 4B Shown are the current densities generated near the edge of the ablation electrode of a conventional pulsed field ablation catheter compared to an enhanced edge transition pulsed field ablation catheter during a procedure. Figure 4A and Figure 4B The current density generated and described in is located outside the electrode and only the Figure 2 As shown in the figure, according to an embodiment of the present disclosure, the first electrode 414, the insulator portion 420 and the second electrode 412 correspond to Figure 2The ring electrode 214, the insulator portion 220 and the tip electrode 212 are shown.

[0081] like Figure 4A As shown, when a voltage is applied to the first electrode 414, a conventional pulsed field ablation design generates an ablation current density 401. At the junction of the electrode and the insulator portion 420, the current density 401 increases significantly, for example, in some cases, the current density approximately doubles. As shown in the figure, conventional pulsed field ablation electrodes generate high current density peaks at the electrode edges. "Edge" or "electrode edge" refers to the transition area between the metal electrode and the insulator portion. As shown by ablation current densities 401 and 402, these high current peaks can cause arcing. Arcing can cause various problems, including thermal damage, gas embolism, and ineffective ablation energy delivery, among other problems.

[0082] like Figure 4B As shown, the enhanced edge transition pulsed field ablation design produces more constant current densities 403 and 404. As shown, each facing electrode pair includes opposing edges. A first electrode 414 is spaced apart from a second electrode 412, and each of the electrodes has a transition region that terminates at the opposing edges. An insulator portion 420 is disposed above the electrodes in the transition region and extends between the first electrode 414 and the second electrode 412. As shown, Figure 4A Unlike the traditional transition from electrode to insulator in the embodiment of the present invention, the enhanced edge transition design includes gradual transition regions 405 and 406. In the transition regions 405 and 406, the diameter (or thickness) of the electrode gradually decreases in the direction toward the opposite edge, while the thickness of the insulator increases in a complementary manner, so that the combination of the electrode and the insulation produces a substantially isodiametric structure. In an embodiment, the transition regions 405 and 406 can be made of a different insulating material than the rest of the insulator portion 420. For example, the transition regions 405 and 406 can be made of a semiconductor material, while the rest of the insulator portion 420 can be completely insulating.

[0083] like Figure 4B As shown, the transition zones 405 and 406 are defined by a spacing length L1. The spacing length L1 defines the longitudinal region between the first electrode 414 and the second electrode 412. As the length of L1 decreases, the current density generated on the ablation electrodes in the transition zones 405 and 406 increases. As shown, the zones 405 and 406 create a transition region where the thickness (or diameter) of the electrode decreases and the thickness of the insulating layer increases. This transition region mitigates the current density peaks seen in conventional designs. In various embodiments, the current density generated at the electrodes and in the transition region is approximately constant. The optimal angle for the tapered transition zones 405 and 406 is to avoid Figure 4AIn an embodiment, the taper angle of transition regions 405 and 406 is between 20 and 60 degrees, and in other embodiments, the taper angle in the transition region is between 30 and 45 degrees.

[0084] As shown in transition region 406, current density 404 gradually increases from the largely insulated electrode edge to the uninsulated entire electrode. Furthermore, the thickness of insulator portion 420 gradually decreases from 100% to 0%. Thus, the enhanced tapered edge transition design reduces the current density generated on the ablation electrode in the transition region. This enhanced design eliminates the large current density peaks created in traditional pulsed field ablation designs and, therefore, eliminates the risk of arcing, sparking, localized heating, electrolytic gas generation, and many other issues.

[0085] In embodiments, the electrode wall thickness may range from 0.0001 inches (e.g. Figure 3 The cardiac ablation catheter 300 can be made from 0.010 inches (for larger electrodes) to 0.010 inches (for larger electrodes). In a further embodiment, assuming an electrode wall thickness of 0.006 inches (0.15 mm), the full thickness insulation at the electrode edge can withstand a voltage of 3 kV - exceeding the maximum voltage of most pulsed field ablation energy applications used for cardiac ablation. The dielectric strength of the insulation determines the gradient of the current density. The dielectric strength ranges from about 15 kV / mm to 60 kV / mm. In embodiments, the insulation material may include polyurethane, Polyetheretherketone (PEEK), polycarbonate, wait.

[0086] Figures 5A to 5D Four other exemplary electrode edge transition stages according to embodiments of the disclosed subject matter are shown. 5A to 5D Half of the transition portion of the electrode edge is shown. As shown, the ideal transition may not be completely linear. Figure 5A A stepped trapezoidal current density electrode edge transition portion 501 is shown. Figure 5B An outwardly curving current density electrode edge transition portion 502 is shown. Figure 5C An inwardly curving current density electrode edge transition 503 is shown. Figure 5D A multi-step current density electrode edge transition is shown 504. Thus, one or more steps, ramps, or a combination of transitions of various geometries may be required to achieve maximum functionality.

[0087] In the various embodiments described above, a variety of techniques can be used to add insulation in the transition region, including, for example, overmolding, reflow, laminate covering, fluorinated masking, or laminating layers with adhesives. In addition, the electrode surface can be textured at the transition to increase the surface area and improve insulation adhesion. In some cases, the electrode surface can be treated with a primer or other adhesive to improve insulation adhesion. In an embodiment, the electrode edges are filleted or rounded. Internal edges may be broken or rounded to prevent mechanical damage caused by bending during device manufacturing and function.

[0088] In an embodiment, a conductive polymer can be used in the insulating transition region to gradually change the resistivity. This can be used as a supplement or alternative to the tapered wall thickness of the electrode or insulating material previously described above. These polymers include but are not limited to polyacetylene, polypyrrole, polyindole, polyaniline and its copolymers, and polyphenylene vinylene (PPV) and its soluble derivatives. These polymers have the ability to adjust the resistivity and can be superior to typical insulating polymers. In addition, in some cases, in order to offset the high current density that may occur in the thinner insulating region, a conductive polymer can be applied in the transition region.

[0089] Note that while the above embodiments are described with respect to a bipolar ablation configuration, the concepts described can also be applied to a monopolar ablation configuration. For example, in such a configuration, a monopolar ablation electrode can extend from an electrode on a catheter to a return electrode positioned externally to the heart, such as an external electrode placed on the patient's skin.

[0090] Embodiments of the present disclosure provide systems, devices and methods for selectively and rapidly applying pulsed electric fields to ablate tissue by irreversible electroporation. In general, the systems, devices and methods described herein can be used to generate larger electric field amplitudes in the desired area of ​​interest and reduce peak electric field values ​​elsewhere to reduce unnecessary tissue damage and arcing. The irreversible electroporation system as described herein may include a signal generator and a processor configured to apply one or more voltage pulse waveforms to a selected electrode group of the ablation device to deliver energy to the area of ​​interest (e.g., ablation energy to a collection of tissues in the pulmonary vein orifices or pulmonary vein sinuses). The pulse waveforms disclosed herein can help therapeutically treat various arrhythmias (e.g., atrial fibrillation). In order to deliver the pulse waveforms generated by the signal generator, one or more electrodes of the ablation device may have insulated electrical leads configured to maintain an electric potential of about several hundred volts to several thousand volts. The electrodes can be independently addressable so that each electrode can be controlled (e.g., deliver energy) independently of any other electrode of the device. In this way, the electrodes can collaboratively deliver different energy waveforms at different timings for electroporation of tissue.

[0091] It is well understood that the use of arguably broad terms such as comprising, referencing, comprised of, or comprising of, are used to describe one embodiment relating to the present disclosure, and are not intended to be limiting of the disclosure to include comparably or similarly situated items unless clearly and unequivocally limited to such scope by the specification or claims. It is further understood that the methods described, including those including one or more steps, are not to be limited by the order of the recited steps unless specifically indicated otherwise in the specification or claims. It is further understood that the methods shown are but a few of the many examples disclosed, and that certain steps can be added or omitted without departing from the scope of the disclosure. Such steps can include those that are routine, conventional, and well understood in the art in connection with devices, systems, or methods, or components thereof.

[0092] The connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and / or physical couplings between the various elements. It should be noted that many alternatives or equivalents would be apparent to those skilled in the art and could be employed in various embodiments without departing from the scope of the disclosure. However, benefits, advantages, solutions to problems, and any element(s) that might cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements. Therefore, the scope is intended to be limited only by the appended claims, wherein means-plus-function or step-plus-function clauses are used where intended, and the specification is to be interpreted in accordance with the full breadth and scope of the claims, wherein the use of the terms "including," "comprising," or "having" and the like are not meant to be construed as limiting as to the term "comprising" or "including" to the extent that the term "comprising" or "including" is used, the specification is intended to also include the terms "consisting of" and "consisting essentially of." Moreover, the use of the term "or" is meant to be construed as a nonexclusive OR, unless explicitly indicated to the contrary. Additionally, the use of the term "at least one" is meant to be construed as "one or more, " unless explicitly indicated to the contrary.

[0093] In the detailed description of the application, references are made to "one embodiment", "an embodiment", "an example embodiment", etc., which indicate that a described embodiment can include a particular feature, structure, or characteristic, but every embodiment can not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one of ordinary skill in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described or claimed. Aspects of the disclosure could be modified, if necessary, to employ the examples, concepts and technologies from other disclosures to produce variations within the scope and spirit of the disclosure.

[0094] In addition, no element, component, or method step in this disclosure is intended to be dedicated to the public, regardless of whether the element, component, or method step is explicitly cited in the claims. No claim element herein shall be interpreted under the provisions of 35 U.S.C. 112(f) unless the element is explicitly recited using the words "for..." As used herein, the terms "comprise," "comprising," or any other variations thereof are intended to cover non-exclusive inclusions such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed or inherent to the process, method, article, or apparatus.

[0095] Various modifications and additions may 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. Therefore, the scope of the present disclosure is intended to encompass all such alternatives, modifications, and variations that fall within the scope of the claims, along with all equivalents thereof.

Claims

1. A catheter for ablation of tissue by irreversible electroporation, the catheter comprising: an elongated body having a proximal end and a distal end; a first electrode spaced proximally from the second electrode along the elongated body, each of the first electrode and the second electrode having a transition region terminating at opposing edges; and an insulator disposed above the electrode in the transition region and extending between the first electrode and the second electrode, Wherein, in the transition region, the electrode thickness of each electrode decreases towards the opposite edge, and the insulator thickness of the insulator correspondingly increases to maintain a substantially constant combined thickness.

2. The ablation catheter according to claim 1, wherein: Each transition region has a substantially similar shape.

3. The ablation catheter according to claim 1, wherein: Each transition region is configured such that when a voltage is applied to each of the electrodes, a current density in the transition region is substantially constant. The ablation catheter according to claim 1 , wherein: Each electrode has a constant cone angle in the transition region. The ablation catheter according to claim 1 , wherein: The insulator portion comprises a dielectric strength from about 15 kV / mm to 60 kV / mm. The ablation catheter according to claim 5 , wherein: The dielectric strength of the insulation determines the gradient of the current density.

7. The ablation catheter according to claim 1, wherein: The transition region condition is formed by tapered insulation on the electrode to create a gradual transition current density from the insulation preform to the electrode, thereby reducing the transition current density. The ablation catheter according to claim 1 , wherein: The transition region may include one or more steps, ramps, or a combination of transitions of various geometric shapes.

9. The ablation catheter according to claim 1 further comprises a third electrode and a fourth electrode and an insulator, wherein the diameter of each of the third electrode and the fourth electrode decreases toward the relative edge in the transition region, and the diameter of the insulator increases accordingly, so that the catheter shaft is substantially of equal diameter.

10. The ablation catheter according to claim 1, wherein: The elongated body includes a tubular shaft having a proximal end and an opposite distal end. The ablation catheter according to claim 10 , wherein: The elongated body also includes a plurality of prongs, each prong including a distal portion coupled to the central hub and a proximal portion coupled to the tubular shaft.

12. The ablation catheter according to claim 11, wherein: The first electrode and the second electrode are disposed on one of the plurality of branches.

13. The ablation catheter according to claim 11, wherein: The electrode assembly also includes a plurality of proximal ablation electrodes located on each branch.

14. The ablation catheter according to claim 10, wherein: The first electrode and the second electrode are disposed on the tubular shaft.

15. The ablation catheter according to claim 10, wherein: Each of the electrodes has a taper angle in the transition region between about 20 and about 60 degrees.

16. A catheter for ablation of tissue by irreversible electroporation, the catheter comprising: an elongated body along a longitudinal axis and having a proximal end and a distal end; a first electrode spaced proximally from the second electrode along the elongated body, each of the first electrode and the second electrode having a transition region terminating at opposing edges; and an insulator disposed above the electrode in the transition region and extending between the first electrode and the second electrode, Wherein, in the transition region, the electrode thickness of each electrode decreases towards the opposite edge, and the insulator thickness of the insulator correspondingly increases to maintain a substantially constant combined thickness.

17. The ablation catheter according to claim 16, wherein: Each transition region has a substantially similar shape.

18. The ablation catheter according to claim 16, wherein: The transition region is configured such that when a voltage is applied to each of the electrodes, a current density in the transition region is substantially constant.

19. The ablation catheter according to claim 18, wherein: Each electrode has a constant cone angle in the transition region.

20. The ablation catheter according to claim 16, wherein The insulator portion includes a dielectric strength of approximately from 15 kV / mm to 60 kV / mm.

21. The ablation catheter according to claim 20, wherein: The dielectric strength of the insulator determines the gradient of the current density.

22. The ablation catheter according to claim 16, wherein: The transition region condition is formed by tapered insulation on the electrode, thereby creating a gradual transition current density from the insulation preform to the electrode to reduce the transition current density.

23. The ablation catheter according to claim 16, wherein: The transition region may include one or more steps, ramps, or a combination of transitions of various geometric shapes.

24. The ablation catheter according to claim 16 further comprises a third electrode and a fourth electrode and an insulator, wherein the diameter of each of the third electrode and the fourth electrode decreases toward the relative edge in the transition region, and the diameter of the insulator increases accordingly, so that the catheter shaft is substantially of equal diameter.

25. A catheter for ablation of cardiac tissue by irreversible electroporation, the catheter comprising: an elongated shaft extending along a longitudinal axis and having a proximal end and a distal end; a tip electrode located at a distal end of the elongated shaft and configured to provide a pulsed field ablation signal; a ring electrode located proximal to and spaced apart from the tip electrode, the first ring electrode having a distal portion; and an insulator disposed between the tip electrode and the first ring electrode, Wherein the distal portion of the ring electrode is tapered in the distal direction along the longitudinal axis in the transition region such that the electrode thickness of the electrode decreases and the insulator thickness of the insulator increases to maintain a substantially uniform catheter diameter.

26. The cardiac ablation catheter according to claim 25, wherein: The tip electrode tapers in the distal direction along the longitudinal axis in the transition region such that the electrode thickness decreases and the insulator thickness increases to maintain a generally uniform catheter diameter.

27. The cardiac ablation catheter according to claim 25, wherein: Each transition region has a substantially similar shape.

28. The cardiac ablation catheter according to claim 25, wherein: The transition region is configured such that when a voltage is applied to each of the electrodes, a current density in the transition region is substantially constant.

29. The cardiac ablation catheter according to claim 28, wherein Each electrode has a constant cone angle in the transition region.

30. The cardiac ablation catheter according to claim 25, wherein The insulator portion comprises a dielectric strength from about 15 kV / mm to 60 kV / mm.

31. The cardiac ablation catheter according to claim 30, wherein: The dielectric strength of the insulation determines the gradient of the current density.

32. The cardiac ablation catheter according to claim 25, wherein: The transition region condition is formed by tapered insulation on the electrode to create a gradual transition current density from the insulation preform to the electrode, thereby reducing the transition current density.

33. The cardiac ablation catheter according to claim 25, wherein: The transition region may include one or more steps, ramps, or a combination of transitions of various geometric shapes.

34. The cardiac ablation catheter according to claim 25, wherein: The elongated shaft further includes third and fourth electrodes and an insulator, wherein the third electrode is tapered distally along the longitudinal axis in the transition region such that the electrode thickness decreases and the insulator thickness increases to maintain a generally uniform catheter diameter.

35. A method of manufacturing a catheter for ablating cardiac tissue by irreversible electroporation, the method comprising: providing an elongated shaft extending along a longitudinal axis and having a proximal end and a distal end; securing a first electrode spaced apart from a second electrode along the elongated axis, each of the electrodes having a transition region terminating at opposing edges; as well as An insulator is fixedly disposed above the electrode in the transition region and extending between the first electrode and the second electrode, wherein the diameter of each of the first electrode and the second electrode decreases in the transition region toward the opposite edge and the diameter of the insulator correspondingly increases so that the catheter shaft is substantially isodiametric.

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