Contoured electrodes for pulsed electric field ablation, and systems, devices, and methods thereof

Abstract

To provide contoured electrodes for pulsed electric field ablation, and systems, devices, and methods thereof.SOLUTION: Systems, devices, and methods are provided herein for delivering pulsed electric fields to ablation tissue (e.g., cardiac tissue). An ablation device can include one or more contoured electrodes with contoured edges that are disposed on an insulating member of the ablation device. The contoured electrodes can be configured to reduce an electric field intensity at an interface between the contoured electrodes and the insulating member and / or a drop-off in electric field intensity.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The embodiments described herein relate generally to medical devices for therapeutic electrical energy delivery, and more particularly to systems, apparatus, and methods for tissue ablation devices (e.g., ablation catheters) having contoured electrodes and using such devices to generate pulsed electric fields. [Background technology]

[0002] Pulsed electric field ablation, which utilizes the application of high voltage pulses, has been demonstrated to be suitable for rapid and effective ablation of cardiac tissue as well as other target anatomy. In the case of the heart, pulsed electric field ablation may generate a localized high electric field configured to drive irreversible electroporation (e.g., disrupting cell membranes resulting in cell death). For example, an ablation catheter configured for focal ablation may be used to deliver pulsed electric field ablation to cardiac tissue via irreversible electroporation. However, high voltage pulses in a fluid medium (e.g., blood) may result in electrolysis and / or the associated generation of gas bubbles. For example, the electric field near the edge of the electrode may be large enough to drive electrical breakdown in the gas bubbles and generate localized flash arcing. The associated high current density at the electrode edge may also result in relatively large gas bubble sizes. In clinical applications, including cardiac tissue ablation, gas bubbles and flash arcing are undesirable. Summary of the Invention

[0003] Described herein is a system, device, and method for ablating tissue through irreversible electroporation.In some embodiments, the device includes a first shaft defining a longitudinal axis and a lumen, a second shaft disposed within the lumen and having a distal portion extending from a distal end of the first shaft, a plurality of electrodes configured to generate an electric field for ablating tissue, and a set of splines, each spline of the set of splines includes a set of electrodes of a plurality of electrodes formed on the splines, each set of electrodes includes a contoured electrode, each contoured electrode includes a proximal edge and a distal edge, at least one of the proximal edge or the distal edge is a contoured edge, the contoured edge has at least one concave or convex portion, and the set of splines is configured to transition to an expanded configuration in which the set of splines bends radially outward from the longitudinal axis of the first shaft.

[0004] In some embodiments, the device comprises a linear shaft defining a longitudinal axis and a plurality of electrodes disposed on a distal portion of the linear shaft, the plurality of electrodes being configured to generate an electric field to ablate tissue, the plurality of electrodes including a tip electrode disposed at a distal end of the linear shaft, the tip electrode including a first contoured edge, and a set of proximal electrodes disposed proximal to the tip electrode, the set of proximal electrodes including a contoured electrode having a second contoured edge, the first and second contoured edges each having at least one concave or convex portion.

[0005] In some embodiments, a method includes generating a pulse waveform using a signal generator coupled to an ablation device, the ablation device including a plurality of electrodes disposed on a distal portion of the ablation device, the distal portion of the ablation device being disposed within the patient's heart; delivering the pulse waveform to a set of electrodes of the plurality of electrodes such that a subset of the set of electrodes is energized with opposite polarity to generate a pulsed electric field to ablate tissue near the distal portion of the ablation device, the set of electrodes including at least one contoured electrode disposed on a flexible member of the ablation device, each contoured electrode having a contoured edge that reduces (1) the intensity of the electric field at the interface between the contoured edge and the flexible member, and (2) the drop in intensity in a direction extending away from the contoured edge. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a block diagram of a system for ablation, according to an embodiment. [Diagram 2] FIG. 2 is a flow diagram of a method for tissue ablation, according to an embodiment. [Diagram 3] FIG. 3 is a schematic diagram of a contoured electrode, according to an embodiment. [Figure 4] FIG. 4 is a perspective view of a contoured electrode, according to an embodiment. [Figure 5A] FIG. 5A is a side view of a contoured electrode, according to an embodiment. [Figure 5B] FIG. 5B is a side view of a deployed contoured electrode, according to an embodiment. [Figure 6] FIG. 6 is a side view of a deployed contoured electrode, according to an embodiment. [Figure 7A] 7A and 7B are side views of a deployed contoured electrode, according to an embodiment. [Figure 7B] 7A and 7B are side views of a deployed contoured electrode, according to an embodiment. [Figure 8] FIG. 8 is a side view of a deployed contoured electrode, according to an embodiment. [Figure 9A] 9A-9E are diagrams of a deployed electrode having two contoured edges, according to an embodiment. [Figure 9B] 9A-9E are diagrams of a deployed electrode having two contoured edges, according to an embodiment. [Figure 9C] 9A-9E are diagrams of a deployed electrode having two contoured edges, according to an embodiment. [Figure 9D] 9A-9E are diagrams of a deployed electrode having two contoured edges, according to an embodiment. [Figure 9E] 9A-9E are diagrams of a deployed electrode having two contoured edges, according to an embodiment. [Figure 10] FIG. 10 is a diagram that diagrammatically depicts a distal end of an ablation device having a linear shaft with contoured electrodes, according to an embodiment. [Figure 11] FIG. 11 is a diagram that diagrammatically depicts a distal end of an ablation device having an expandable structure with contoured electrodes, according to an embodiment. [Figure 12] FIG. 12 is a side view of a deployed contoured electrode of the ablation device depicted in FIG. 11, according to an embodiment. [Figure 13] FIG. 13 is a diagram that diagrammatically depicts a distal end of an ablation device including a contoured electrode and having a basket shape, in accordance with an embodiment. [Figure 14] FIG. 14 is a diagram that diagrammatically depicts a contoured electrode of the ablation device depicted in FIG. 13, according to an embodiment. [Figure 15A] 15A and 15B are schematic side views of a spline or shaft of an ablation device without and with contoured electrodes, respectively, in accordance with an embodiment. [Figure 15B]15A and 15B are schematic side views of a spline or shaft of an ablation device without and with contoured electrodes, respectively, in accordance with an embodiment. [Figure 16] FIG. 16 is a graph of the electric field intensity along the side of a shaft as depicted in FIGS. 15A and 15B, according to an embodiment. [Figure 17A] 17A and 17B are schematic depictions of a spline or shaft of an ablation device having two adjacent electrodes with contoured edges, according to an embodiment. [Figure 17B] 17A and 17B are schematic depictions of a spline or shaft of an ablation device having two adjacent electrodes with contoured edges, according to an embodiment. [Figure 18] FIG. 18 is a diagram that diagrammatically depicts a shaft or spline or ablation device having electrodes without and with opposing contoured edges according to an embodiment, and a graph of the electric field intensity along the side of the shaft. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Described herein are systems, devices, and methods for delivering a pulsed electric field to ablate tissue by irreversible electroporation. In some embodiments, the systems, devices, and methods described herein may be used to generate a pulsed electric field with improved (e.g., reduced) local electric field and current density at the electrode edge, for example, by suitable contouring of the electrode edge as described herein. The systems, devices, and methods disclosed herein can generate a local electric field in a tissue region sufficient to drive irreversible electroporation while maintaining electric field values ​​below safe levels in a given tissue region.

[0008] The term "electroporation" as used herein refers to the application of an electric field to a cell membrane to change the permeability of the cell membrane to the extracellular environment. The term "reversible electroporation" as used herein refers to the application of an electric field to a cell membrane to temporarily change the permeability of the cell membrane to the extracellular environment. For example, a cell that has undergone reversible electroporation can be observed to have a temporary and / or intermittent formation of one or more pores in its cell membrane that close upon removal of the electric field. The term "irreversible electroporation" as used herein refers to the application of an electric field to a cell membrane to permanently change the permeability of the cell membrane to the extracellular environment. For example, a cell that has undergone irreversible electroporation can be observed to have a temporary and / or intermittent formation of one or more pores in its cell membrane that persist upon removal of the electric field.

[0009] In some embodiments, the electrodes are configured to generate an electric field with improved spatial uniformity. For example, an ablation device may include a set of contoured electrodes. In some embodiments, an ablation device including a catheter shaft may include one or more of the electrodes described herein. In some embodiments, a linear catheter ablation device may include a catheter shaft and a distal cap. The distal cap may include one or more distal cap electrodes corresponding to any of the electrodes described herein. In some embodiments, a catheter device for cardiac ablation may be made with electrodes in the form of cylindrical rings mounted on a catheter shaft made from a polymeric material. In some embodiments, a balloon ablation device or other ablation device with an expandable structure may have a distally located inflatable balloon or expandable structure with a contoured electrode formed on the balloon or expandable structure.

[0010] system Disclosed herein are systems and devices configured to generate tissue ablation. Generally, described herein are systems for ablating tissue using high-voltage pulse waveforms. The systems, methods, and implementations described in this disclosure apply to synchronous or asynchronous ablation delivery. Furthermore, as described herein, the systems and devices can be deployed endocardially and / or epicardially to treat cardiac arrhythmias.

[0011] Disclosed herein are systems and devices configured for tissue ablation via selective and rapid application of voltage pulse waveforms to assist tissue ablation resulting in irreversible electroporation. In general, the systems for ablating tissue described herein may include a signal generator and an ablation device having one or more electrodes for selective and rapid application of direct current (DC) voltage to drive electroporation. As described herein, the systems and devices may be deployed epicardially and / or endocardially to treat cardiac arrhythmias. To deliver pulsed electric field ablation therapy, a voltage may be applied to a selected paired subset of electrodes by selecting independent subsets for anode and cathode electrode selection. In embodiments, the paired electrode subsets may be predetermined. In some embodiments, a pacing signal for cardiac stimulation may be generated and used to deliver an ablation pulse waveform by a signal generator in synchronization with the pacing signal.

[0012] Generally, the systems and devices described herein include one or more catheters configured to ablate tissue of the heart (e.g., the left atrium of the heart). The catheter can include an electrode having at least one edge having a contour that includes a convex portion and a concave portion. In some embodiments, the one or more electrodes can be embodied as a ring electrode on the catheter shaft. In some embodiments, the one or more electrodes can be embodied in other forms, including, for example, a distal cap electrode of a linear catheter ablation device.

[0013] 1 shows an ablation system 100 configured to deliver a voltage pulse waveform. System 100 may include an apparatus 120 including a signal generator 122, a processor 124, a memory 126, and optionally a cardiac stimulator 128. Apparatus 120 may be coupled to an ablation device 110 and may optionally be coupled to a pacing device 130.

[0014] The signal generator 122 may be configured to generate a pulse waveform for irreversible electroporation of tissue, such as, for example, a pulmonary vein ostium. For example, the signal generator 122 may be a voltage pulse waveform generator and may deliver a pulse waveform to the ablation device 110. The processor 124 may incorporate data received from the memory 126 to determine parameters (e.g., amplitude, width, duty cycle, etc.) of the pulse waveform generated by the signal generator 122. The memory 126 may further store instructions that cause the signal generator 122 to execute modules, processes, and / or functions associated with the system 100, such as pulse waveform generation and / or cardiac pacing synchronization. For example, the memory 126 may be configured to store pulse waveform and / or cardiac pacing data for pulse waveform generation and / or cardiac pacing, respectively.

[0015] In some embodiments, the ablation device 110 can be configured to receive and / or deliver pulsed waveforms, which are described in more detail below. For example, the ablation device 110 can be introduced into the endocardial space of a cardiac chamber (e.g., the left atrium) and positioned to position one or more electrodes 112 at one or more pulmonary vein ostia, and then deliver a pulsed waveform to ablate tissue. The ablation device 110 can include one or more electrodes 112, and in some embodiments, can include at least one set of independently addressable electrodes. Each electrode can include an insulated electrical lead configured to maintain a potential of at least about 700 V without breakdown of its corresponding insulation. In some embodiments, the insulation on each electrical lead can maintain a potential difference of about 200 V to about 4,000 V across its thickness without breakdown. For example, the electrodes 112 may be grouped into one or more paired subsets or anode-cathode subsets (e.g., a subset having multiple electrodes configured to have opposite polarity), such as, for example, a subset including one anode and one cathode, a subset including two anodes and two cathodes, a subset including two anodes and one cathode, a subset including one anode and two cathodes, a subset including three anodes and one cathode, a subset including three anodes and two cathodes, and / or the like.

[0016] In some embodiments, the ablation device 110 includes a catheter defining a longitudinal axis. The catheter can include a catheter distal end, a distal portion disposed distal to the catheter distal end, and at least one spline. The spline can include a spline proximal end and a spline distal end, the spline proximal end coupled to the catheter distal end, and the spline distal end coupled to the distal portion. Additionally, the spline can include a first electrode disposed over a portion of a surface of the spline, the first electrode comprising a surface having a proximal boundary and a distal boundary. The proximal and distal boundaries can include closed curves, the distal boundary being located closer to the spline distal end, and the proximal boundary being located closer to the spline proximal end. Additionally, the spline can include a second electrode located closer to the spline proximal end than the first electrode.

[0017] In some embodiments, the electrodes 112 may include one or more contoured electrodes 114. The contoured electrodes 114 include one or more contoured edges. The contoured edges may include an electrode edge that includes at least one peak or at least one valley, as described further below.

[0018] The pacing device 130 may be suitably coupled to a patient (not shown) and configured to receive a cardiac pacing signal generated by a cardiac stimulator 128 of the apparatus 120 for cardiac stimulation. An indication of the pacing signal may be transmitted by the cardiac stimulator 128 to the signal generator 122. Based on the pacing signal, an ablation voltage pulse waveform may be selected, calculated, and / or otherwise identified by the processor 124 and generated by the signal generator 122. In some embodiments, the signal generator 122 is configured to generate a pulse waveform synchronously with the indication of the pacing signal (e.g., within a common refractory window). For example, in some embodiments, the common refractory window may begin substantially immediately (or after a very small delay) after the ventricular pacing signal and continue thereafter for a duration of about 250 milliseconds or less. In such embodiments, the entire pulse waveform may be delivered within this duration. In alternative embodiments, the ablation pulse waveform may be delivered without a pacing signal, i.e., asynchronously, and thus a pacing device may not be required.

[0019] The processor 124 may be any suitable processing device configured to run and / or execute a set of instructions or code. The processor may be, for example, a general purpose processor, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), a digital signal processor (DSP), and / or the like. The processor may be configured to run and / or execute application processes and / or other modules, processes and / or functions associated with the system and / or its associated network (not shown). The underlying device technology may be provided in a variety of component types, for example, metal oxide semiconductor field effect transistor (MOSFET) technology such as complementary metal oxide semiconductor (CMOS), bipolar technology such as emitter coupled logic (ECL), polymer technology (e.g., silicon-conjugated polymer and metal-conjugated polymer-metal structures), mixed analog and digital, etc.

[0020] The memory 126 may include a database (not shown) and may be, for example, a random access memory (RAM), a memory buffer, a hard drive, an erasable programmable read only memory (EPROM), an electrically erasable read only memory (EEPROM), a read only memory (ROM), a flash memory, etc. The memory 126 may store instructions that cause the processor 124 to execute modules, processes, and / or functions associated with the system 100, such as pulse waveform generation and / or cardiac pacing.

[0021] The system 100 may communicate with other devices (not shown) via one or more networks, each of which may be any type of network, for example. A wireless network may refer to any type of digital network that is not connected by any type of cable. However, a wireless network may be connected to a wired network to interface with the Internet, other carrier voice and data networks, business networks, and personal networks. Wired networks are typically transmitted over copper twisted pair, coaxial cable, or fiber optic cable. There are many different types of wired networks, including wide area networks (WANs), metropolitan area networks (MANs), local area networks (LANs), campus area networks (CANs), global area networks (GANs) such as the Internet, and virtual private networks (VPNs). Hereinafter, a network refers to any combination of combined wireless, wired, public, and private data networks that are typically interconnected via the Internet to provide an integrated networking and information access solution.

[0022] 3 is a schematic diagram of a contoured electrode 314 having contoured edges 313 and 315 disposed on a shaft or spline 318, according to various embodiments. The shaft or spline 318 may belong to an ablation device, such as, for example, the ablation device 110 as described above. The ablation device may include one or more splines or shafts 318 having multiple electrodes (including the contoured electrode 314) disposed at distinct locations along the length of the spline or shaft. In some cases, the shaft 318 may include a cross-section that is substantially constant. For example, the shaft 318 may have a cross-section that is substantially circular, elliptical, etc. Alternatively, the shaft 318 may include sections having different cross-sections.

[0023] Each contoured electrode 314 can have a first and second edge having at least one contoured edge 313, 315. For example, the contoured electrode 314 can have a single contoured edge 313. Alternatively, the contoured electrode 314 can have two contoured edges 313, 315. The contoured edges 313, 315 can be edges that include at least one peak and at least one valley when viewed along the width of the shaft 318. For example, the shaft 314 can have a longitudinal axis 302 and a transverse axis 304 (i.e., an axis extending along the width of the shaft 314). A straight or non-contoured edge can be an edge that extends parallel to the axis 304, while a contoured edge (e.g., edge 313 or 315) can be an edge that has at least one portion that is angled (or has an angled unit tangent) with respect to the axis 304. In some embodiments, the contoured edge can have a periodic curve with multiple peaks and valleys, while in other embodiments, the contoured edge can have a single peak and a single valley.

[0024] FIG. 4 is a perspective view of an electrode 414 with a first edge 413 and a second edge 415, according to an embodiment. The electrode 414 may be an example of a contoured electrode 114, 314, as described above with respect to FIGS. 1 and 3, respectively. For example, the electrode 414 may be disposed on a spline or shaft (e.g., shaft 318) of an ablation device (e.g., ablation device 110). The first edge 413 may be opposite the second edge 415. For example, the first edge 413 may be a proximal edge and the second edge 415 may be a distal edge, or vice versa. The electrode 414 may be, for example, generally cylindrical or annular (e.g., ring-like) in shape. In some embodiments, the electrode 414 may include a circular, elliptical, flattened elliptical, or oval cross-section.

[0025] In some embodiments, the edges 413, 415 may include a non-linear shape. For example, the edges 413, 415 may include a generally wavy pattern. As shown in FIG. 4, the edges 413, 415 may be contoured edges that are shaped (e.g., contoured) into a wave shape having peaks and valleys. In some embodiments, the edges 413, 415 may include one or more patterns. In some embodiments, the edge pattern may be one or more of a sinusoid or a curve. In some variations, the edge pattern may be periodic. In some embodiments, the edges 413, 415 may be rounded (e.g., smooth) or may include corners.

[0026] In some embodiments, the edges 413, 415 may or may not be symmetrical with respect to themselves or other edges. In some embodiments, the edges may be the same or different with respect to other edges. In some embodiments, the edges may extend along the circumference of the electrode. In some embodiments, the contour may extend along a portion of the circumference of the electrode.

[0027] FIG. 5A illustrates an example of an electrode 501 according to an embodiment. The electrode 601 may be an example of a contoured electrode 114, 314, as described above with respect to FIGS. 1 and 3, respectively. For example, the electrode 501 may be disposed on a spline or shaft (e.g., shaft 318) of an ablation device (e.g., ablation device 110). The electrode 501 may include a first edge 513 and a second edge 515. The first edge 513 may be a proximal edge and the second edge 515 may be a distal edge, or vice versa. In an exemplary embodiment, the cross section 503 may be of a constant shape (constant cross section along the longitudinal axis). The distal edge 513 may be contoured (e.g., wavy), while the proximal edge 515 may not be contoured (such edges are referred to herein as uncontoured edges, straight edges, flat edges, or in-plane edges). The uncontoured edge 515 may lie in a single plane perpendicular to the longitudinal axis 505 of the electrode 501 .

[0028] 5B and 6 show views of the electrode 501 cut in a direction parallel to the axis 505 and unfolded (e.g., flattened). In this rendering, the proximal edge 515 is straight and the distal edge 513 includes a set of peaks 522 and valleys 524. The surface of the electrode 501 is represented by region 525. In various embodiments, the region 525 may be made of any suitable conductive material (e.g., metal) that is biocompatible. As shown in FIG. 5A, a selected transverse plane 514 intersects the electrode 501 and is perpendicular to the electrode or spline axis 505. A cross section 503 is within the transverse plane 514. In some embodiments, the electrode 501 may include a cross section 503 that is circular, elliptical, flattened elliptical, or oval.

[0029] In various embodiments, the peaks 522 may be convex portions and the valleys 524 may be concave portions. For example, one or more convex portions (e.g., peaks 522) of the distal edge 513 may be configured to bulge outward such that a point on a line connecting any two points on the convex portions is inside the area bounded by the boundary of the electrode 501. Similarly, one or more concave portions (e.g., valleys 524) may be configured such that a point on a line connecting any two points on the concave portions is outside the area bounded by the boundary of the electrode 501. The convex and concave portions may each include one or more generally curvilinear portions.

[0030] 6, the electrode 501 can have an associated circumferential direction D1 and an associated longitudinal direction D2. In an exemplary embodiment, the edge 513 has a peak point P P to the closest point p1 associated with edge 515, H P is the valley point P of the edge 513 V to the closest point p2 associated with edge 515, H V In an exemplary embodiment, H P may be the maximum distance between the closest points of edges 513 and 515, and H V may be the minimum distance between the closest points of edges 513 and 515. As shown in FIG. P corresponds to the distance between the crest of edge 513 and the associated closest point of edge 515, and H V corresponds to the distance between the valley of edge 513 and the associated closest point of edge 515.

[0031] The contoured edge 513 can have a corrugation characterized by a wavelength and a peak height or wave depth. P and H V The difference between H and H corresponds to the depth of the wave. P -H V =H PV Additionally, the contoured edge 513 may be characterized by a predetermined wavelength L. In some embodiments, HPV (i.e., wave depth) H P (i.e., the maximum electrode length along its longitudinal axis) may be from about 0.05 to about 0.75, including all values ​​and subranges therebetween.

[0032] In various embodiments, the number of peaks on the contoured edge 513 can depend on (1) the width W of the edge 513, which can correspond to the circumference of the spline or shaft of the ablation device, and (2) the wavelength L. For example, the number of peaks N P is N P .about.W / L. In embodiments described herein, the edge 513 may have about 1, about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10, or more peaks along with an associated number of valleys.

[0033] 7A and 7B show an unfolded (e.g., unfolded) view of an electrode 601 (e.g., a ring electrode) including a first edge 613 and a second edge 615, according to an embodiment. The electrode 601 may be an example of a contoured electrode 114, 314, as described above with respect to FIGS. 1 and 3, respectively. For example, the electrode 601 may be disposed on a spline or shaft (e.g., shaft 318) of an ablation device (e.g., ablation device 110). The first edge 613 may be a proximal edge and the second edge 615 may be a distal edge, or vice versa. The first edge 613 may be a contoured edge and have a corrugation, while the second edge 615 may be a non-contoured edge and be straight in this unfolded rendering. The first edge 613 may include a set of peaks 624 (e.g., convex peaks) and valleys 625 (e.g., concave valleys). In some embodiments, each valley 625 has the same first length L V and each peak 624 may have the same second length L P In some embodiments, the first length L V is the second length L PAs shown in Figure 7A, the first and second lengths are measured in a circumferential direction, as described above with reference to Figure 6.

[0034] Alternatively, in some embodiments, the first length L V is the second length L P It may be equal to (or smaller than) L V =L P , such an embodiment is referred to as a symmetric embodiment. Alternatively, in some embodiments, one or more crests 624 may have unequal lengths and / or one or more valleys 625 may have unequal lengths, e.g., the length of the valleys and the length of the crests may generally differ. In such an embodiment, the wave may be referred to as an asymmetric wave. In some embodiments, the electrode 601 may have a single crest 624 and a single valley 625, and in alternative embodiments, the electrode 601 may have multiple crests 624 and / or multiple valleys 625.

[0035] In some embodiments, the longest dimension of the cross section of electrode 601 (e.g., diameter of electrode 601) can be from about 0.5 mm to about 6 mm, including all values ​​and subranges therebetween. In some embodiments, the electrode length can be from about 0.5 mm to about 9 mm, including all values ​​and subranges therebetween. In some embodiments, the length of the peak of first edge 613 can be from about 20 μm to about 20,000 μm, including all values ​​and subranges therebetween. In some embodiments, the length of the valley of first edge 613 can be from about 20 μm to about 20,000 μm, including all values ​​and subranges therebetween.

[0036] The valleys 625 and peaks 624 may be characterized by associated curvatures. In an exemplary embodiment, the valleys may have a first center of curvature 633, as shown in FIG. 7B. The first center of curvature 633 may be outside of the area enclosed by the boundary of the electrode 601, as shown in FIG. 7B, and may include an associated first radius of curvature 634. The second center of curvature 635 may correspond to the peaks 625. The second center of curvature 635 may be inside of the area enclosed by the boundary of the electrode 601, as shown in FIG. 7B, and may include an associated second radius of curvature 636.

[0037] In some embodiments, the minimum radius of curvature 634 of the concave portion 637 of the valley 625 may be at least about 10 μm. In some embodiments, the minimum radius of curvature 636 of the convex portion 638 of the peak 624 may be at least about 10 μm. In some embodiments, the maximum radius of curvature 634 of the one or more concave portions 637 may be less than about 50,000 μm. In some embodiments, the maximum radius of curvature 636 of the one or more convex portions 638 may be less than about 500 μm. In some embodiments, one or more of the convex portion 638 and the concave portion 637 of the edge 613 of the electrode 601 may include an arc or be shaped as an arc. In some embodiments, the ratio of the radius of curvature of the at least one concave arc to the radius of curvature of the at least one convex arc may be greater than about 10.

[0038] In some embodiments, the tangential discontinuities may be included as peaks or valleys in the contoured edge of the electrode. FIG. 8 is a side view in an unfolded rendering of an electrode 701 (e.g., a cylindrical ring electrode) including a first edge 713 and a second edge 715, according to an embodiment. The electrode 701 may be an example of a contoured electrode 114, 314, as described above with respect to FIGS. 1 and 3, respectively. For example, the electrode 701 may be disposed on a spline or shaft (e.g., shaft 318) of an ablation device (e.g., ablation device 110). The first edge 713 may be opposite the second edge 715. For example, the first edge 713 may be a proximal edge and the second edge 715 may be a distal edge, or vice versa. The first edge 713 may include a set of concave portions, such as portions 730, 734. In some embodiments, the first edge 713 may have one or more tangent discontinuities between adjacent concave portions 730 and 734, which may be peaks 732 of the electrode 701. That is, the peaks 732 may be tangent discontinuities.

[0039] 9A-9E show example electrodes 801-805 having contoured first edges 811A-811E and contoured second edges 812A-812E, according to various embodiments. As shown, the contoured edges 811A-811E, 812A-812E may be symmetrical and / or different in wavelength and / or wave depth. The electrodes 801-805 are shown deployed (e.g., unfolded) in FIGS. 9A-9E. The electrodes 801-805 may be examples of contoured electrodes 114, 314, as described above with respect to FIGS. 1 and 3, respectively. For example, the electrodes 801-805 may be disposed on a spline or shaft (e.g., shaft 318) of an ablation device (e.g., ablation device 110).

[0040] In the exemplary embodiment shown in FIG. 9A, edges 811A, 811B of electrode 801 may be symmetrical with respect to each other in reflection, for example edge 812A may have reflection symmetry with edge 811A such that the crest of edge 812A is aligned with the valley of edge 811A. In particular, as shown in FIG. A V A Alternatively, in the exemplary embodiment shown in FIG. 9B, edges 811B, 812B of electrode 802 may be symmetrical with respect to each other in translation, e.g., edge 812B is aligned with valley V1. B Gaya V2 B Lined up with Yama P1 B GayamaP2 B 9C shows an electrode 803 having contoured edges 811C and 812C that form a phase shift pattern characterized by edge 812C having the same peaks and valleys as edge 811C, but phase shifted by a predetermined value φ. Alternatively, FIG. 9D shows an electrode 804 in which the amplitudes of contoured edges 811D and 812D are different. For example, edge 812D can have a smaller peak amplitude or wave depth relative to edge 811D. Alternatively, FIG. 9E shows an embodiment of an electrode 805 having contoured edges 811E and 812E with different wavelengths and wave depths. For example, edge 812E can have a smaller wavelength than edge 811E, and therefore a greater number of peaks and valleys.

[0041] 9A and 9E show different variations of electrodes with two contoured edges, it should be understood that any edge configurations may be combined in any suitable manner, for example, an amplitude variation pattern (FIGS. 9D and 9E) may be combined with a phase shift pattern (FIG. 9C).

[0042] FIG. 10 illustrates a distal end of an exemplary ablation device 910, according to an embodiment. The ablation device 910 may be structurally and / or functionally similar to other ablation devices described herein, including, for example, the ablation device 110 described with reference to FIG. 1. The ablation device 910 may be an example of a linear ablation device. For example, the ablation device 910 includes a shaft 905 and a plurality of electrodes 906, 907, 908 disposed along the shaft 905. In some embodiments, the plurality of electrodes 906, 907, 908 may be configured to deliver an ablation therapy, including high voltage electrical pulses for pulsed electric field ablation or irreversible electroporation. A sleeve or sheath 930 may be optionally disposed over a portion of the shaft 905. The sheath 930 and the shaft 905 may be configured to move relative to one another to expose a greater number or portion of the electrodes disposed along the shaft 905. In this manner, sleeve 930 can be used to reduce or increase the number of electrodes that are exposed outside of sleeve 930 and available to deliver ablation. Suitable examples of linear ablation devices are described in International Application PCT / US2020 / 037948, filed June 16, 2020, and entitled "SYSTEMS, DEVICES, AND METHODS FOR FOCAL ABLATION," the contents of which are incorporated herein by reference in their entirety.

[0043] In some embodiments, the ablation device 910 may be configured to be steered or deflected by a suitable deflection control mechanism, such as, for example, pull wires 912. In some embodiments, one or more portions of the shaft 905 may be configured to be flexible and may be bendable via the deflection control mechanism 912. Additionally or alternatively, one or more portions of the shaft 905, such as the portions on which the electrodes 906, 907, 908 are disposed, may be rigid.

[0044] In some embodiments, the distal end of the ablation device 910 may include a distal tip electrode 908, implemented, for example, as a distal cap electrode. Electrodes 906 and 907 may be disposed proximal to the distal tip electrode 908. In some embodiments, electrodes 907 and 908 may be generally cylindrical (e.g., ring-shaped) with proximal and distal edges. For example, electrodes 906 and 907 may have respective edges 916, 918 and 920, 922. Distal tip electrode 908 may have a single edge 924. In some embodiments, one or more of edges 916, 918, 920, 922, 924 may be contoured edges. For example, as shown in FIG. 10, distal edge 922 of electrode 907 and proximal edge 924 of distal tip electrode 908 may each have a contoured (e.g., wavy, curved) shape, as further described herein. In some embodiments, one or more peaks or valleys of contoured edges 922 and 924 may be aligned (e.g., in line) along the longitudinal axis of ablation device 910. Additionally or alternatively, one or more peaks or valleys of contoured edges 922 and 924 may not be aligned with one another.

[0045] 11 shows a distal end of an exemplary ablation device 1000, according to an embodiment. Ablation device 1000 may be structurally and / or functionally similar to other ablation devices described herein, including, for example, ablation device 110 described with reference to FIG. 1. Ablation device 1000 may be an example of a balloon ablation device or other ablation device having an expandable or inflatable structure. For example, ablation device 1000 may include a catheter shaft 1010 and an inflatable member 1011 (e.g., a balloon) disposed at a distal portion of ablation device 1000. For example, suitable examples of balloon ablation devices for focal ablation are described in International Application PCT / US18 / 50660, filed September 12, 2018, entitled "SYSTEMS, APPARATUSES, AND METHODS FOR VENTRICULAR FOCAL ABLATION," and published as International Application Publication WO2019 / 055512, the contents of which are incorporated herein by reference in their entirety.

[0046] In some embodiments, the ablation device 1000 may include a distal tip 1012. In some embodiments, the expandable member 1011 may include one or more electrodes 1013 and 1014 disposed on a surface of the expandable member 1011. For example, the expandable member 1011 may be constructed from a polymeric material and the electrodes 1013 and 1014 may be constructed from a metal film deposited on the expandable member 1011. As shown in FIG. 11, the electrodes 1013 and 1014 may be contoured as described herein and may include one or more convex and concave portions along one or more edges. For example, the electrode 1013 includes an edge having concave portions 1026, 1027, 1028, and convex portions 1025, 1029.

[0047] In some embodiments, the shaft 1010 may define a lumen configured for a guidewire (not shown) to be slidably disposed therein. For example, the guidewire may be configured for over-the-wire delivery of the ablation device 1000 to a predetermined location within a patient. Although not shown in FIG. 11, in some embodiments, the catheter shaft 1010 may include one or more contoured electrodes having a profile having any of the structures described herein.

[0048] In various embodiments, the electrodes 1013 and 1014 are configured to be stretchable or expandable. Any suitable technique can be used to form a stretchable electrode (e.g., an electrode formed using a network of conductive overlapping filaments, such as metal nanowires, embedded in (or disposed over) a stretchable and flexible substrate). In some cases, the stretchable electrode may be formed from a network of folded conductive elements configured to unfold to allow the stretchable electrode to extend in one or more directions.

[0049] In some embodiments, electrodes such as electrodes 1013, 1014 shown in FIG. 11 may include multiple concave and / or multiple convex portions (e.g., multiple waves) having unequal lengths and / or radii of curvature. The electrodes may be disposed on a balloon ablation catheter as depicted with respect to FIG. 11, or the electrodes may be disposed on a shaft or spline of a linear or basket ablation catheter. For example, FIG. 12 shows an exemplary diagram of a ring electrode 1101 in a deployed configuration having a contoured edge 1113 that includes multiple concave and / or multiple convex portions (e.g., multiple waves) having unequal lengths and / or radii of curvature. The electrode 1101 may be an example of a contoured electrode 114, 314, as described above with respect to FIG. 1 and FIG. 3, respectively. For example, the electrode 1101 may be disposed on a spline or shaft (e.g., shaft 318) of an ablation device (e.g., ablation device 110).

[0050] The electrode 1101 includes a first edge 1113 and a second edge 1115. For example, the first edge 1113 may have a generally asymmetric and non-uniform wave shape, while the second edge 1115 may be straight (i.e., not contoured). The first edge 1113 may include a set of peaks 1102, 1110 and valleys 1103, 1104, 1112. The peaks 1102, 1110 may be convex portions, and the valleys 1103, 1104, 1112 may be concave portions. The first edge 1113 may include a generally asymmetric wave.

[0051] In some embodiments, the first center of curvature 1105 corresponds to the valley 1112. The first center of curvature 1105 may be outside of the area enclosed by the boundary of the electrode 1101 and may include an associated first radius of curvature 1106. The second center of curvature 1107 corresponds to the valley 1103. The second center of curvature 1107 may be outside of the area enclosed by the boundary of the electrode 1101 and may include an associated second radius of curvature 1108. The first radius of curvature 1106 may be different from the second radius of curvature 1108. In some embodiments, the valleys may have different lengths. For example, the valley 1104 may have a first length 1109 and the valley 1103 may have a second length 1111.

[0052] 13 shows an ablation device 1301 having electrodes 1311-1316, according to an embodiment. Ablation device 1301 may be structurally and / or functionally similar to other ablation devices described herein, including, for example, ablation device 110 described with reference to FIG 1. Ablation device 1301 may be an example of a basket ablation device or other type of expandable ablation device.

[0053] 13, includes a shaft 1310 at a proximal end of the device 1301, a guidewire lumen 1317, a distal tip 1307, and one or more splines 1302, 1303. The guidewire lumen 1317 can be configured to be disposed within the shaft 1310 and extend to the distal tip 1307. A guidewire (not shown) can be configured to be slidably disposed within the guidewire lumen 1317. For example, the guidewire can be configured for over-the-wire delivery of the ablation device 1301 to a predetermined location within a patient.

[0054] In some embodiments, one or more of the splines 1302, 1303 may include one or more electrodes (e.g., ring electrodes) disposed along their length. For example, electrodes 1311, 1313, 1315 may be disposed on spline 1303, and electrodes 1312, 1314, 1316 may be disposed on spline 1302. Distal tip 1307 may include an atraumatic shape to reduce trauma to tissue. A proximal end of the set of splines 1302, 1303 (or a single spline if only one spline is used) may be coupled to a distal end of the catheter shaft 1310, and a distal end of the set of splines 1302, 1303 (or a single spline if only one spline is used) may be coupled to a distal tip 1307 of the device 1301.

[0055] The ablation device 1301 may be configured to deliver a pulse waveform to tissue via electrodes 1311-1316 disposed on the splines 1302, 1303. In an exemplary embodiment, any suitable number of splines may be used (e.g., there may be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. splines). In an exemplary embodiment, the ablation device 1301 includes from 3 to 20 or more splines, including all values ​​and subranges therebetween. In some cases, the ablation device 1301 may include more than 20 splines.

[0056] The splines 1302 and 1303 may include one or more wired together or independently addressable electrodes 1311-1316 formed on the surface of the splines 1302, 1303. Each electrode (e.g., electrodes 1311-1316) may include an insulated electrical lead configured to maintain a potential of at least about 700V without breakdown of its corresponding insulation. In some embodiments, the insulation on each electrical lead is capable of maintaining a potential difference of about 200V to about 4,000V across its thickness without breakdown. Each spline 1302, 1303 may include or contain insulated electrical leads of their electrodes formed on the body of that spline 1302, 1303 (e.g., within the lumen of the spline). When the electrodes on a single spline are wired together, a single insulated lead may carry strands that connect to the different electrodes on the spline.

[0057] In some embodiments, the distal electrodes 1315, 1316 (and / or any of the electrodes) may include distal edges 1338, 1339, respectively, having a contoured shape as described herein. In some embodiments, different splines may include electrodes having different contours and / or the distal and proximal electrodes on each spline may include electrodes having different contours according to embodiments described herein. The electrodes on each spline 1302, 1303 may be grouped into a set of distal electrodes (i.e., electrodes 1315, 1316) and proximal electrodes (i.e., electrodes 1311, 1312, 1313, 1314). In some embodiments, the proximal electrodes 1311, 1312, 1313, 1314 may be substantially similar in size and shape. Proximal electrodes 1311 and 1313 (and similarly proximal electrodes 1312 and 1314) may be spaced apart from one another by a first distance, and the distal edge of proximal electrode 1313 and the proximal edge of distal electrode 1315 (and similarly the distal edge of proximal electrode 1314 and the proximal edge of distal electrode 1316) may be spaced apart from one another by a second distance. In some embodiments, the first distance and the second distance may be different. For example, the second distance may be greater than the first distance. Alternatively, the first distance and the second distance may be the same. Although a particular spacing and arrangement of the electrodes is described herein, it can be understood that the size, shape, and spacing of the electrodes may be different without departing from the scope of the present disclosure.

[0058] In various embodiments, splines 1302 and 1303 may be flexible. In some embodiments, ablation device 1301 may be configured to be deployed by pulling guidewire lumen 1317 by an actuation mechanism disposed in a handle (not shown) of ablation device 1301. As guidewire lumen 1317 is retracted along shaft 1310, splines 1302, 1303 may be configured to bend outward in an expanded configuration (e.g., in a basket-like shape). In some embodiments, ablation device 1301 may not have a guidewire lumen, and instead may include a deflection mechanism (e.g., a pull wire) to steer ablation device 1301 toward a predetermined anatomical target. In some cases, the splines 1302, 1303 may be configured to transform between a first configuration (e.g., an undeployed configuration) in which the splines 1302, 1303 are disposed substantially parallel to the longitudinal axis of the ablation device 1301, and a second configuration (e.g., an extended or deployed configuration) in which the splines 1302, 1303 bend radially outward from the longitudinal axis of the ablation device 1301 (or the longitudinal axis of the shaft 1310). In some embodiments, the splines 1302, 1303 in the second configuration may form a basket having an asymmetric shape along its length such that one end (e.g., a distal end) of the basket is more bulbous than the other end (e.g., a proximal end) of the basket.

[0059] In some embodiments, when suitably deployed, the splines may be configured to form a generally planar petal-like configuration (e.g., a flower configuration) or to form a basket. For example, the ablation devices disclosed herein may include structural and / or functional components similar to those described in U.S. Patent No. 10,172,673, filed September 21, 2017 and entitled "SYSTEMS DEVICES, AND METHODS FOR DELIVERY OF PULSED ELECTRIC FIELD ABLATIVE ENERGY TO ENDOCARDIAL TISSUE," and U.S. Patent No. 10,660,702, filed April 3, 2020 and entitled "SYSTEMS, DEVICES, AND METHODS FOR FOCAL ABLATION," the contents of each of which are incorporated herein by reference in their entirety.

[0060] In one embodiment, the proximal electrodes 1311, 1312, 1313, 1314 can be configured to have a first polarity and the distal electrodes 1315, 1316 can be configured to have a second polarity opposite the first polarity. In such a case, the proximal electrodes 1311, 1312, 1313, 1314 and the subset of distal electrodes 1315, 1316 can be configured to function as a paired anode-cathode subset. Alternatively, a different combination of electrodes can be selected to function as an anode-cathode subset. The paired anode-cathode subset can be configured to deliver pulsed electric field ablation to tissue as described with reference to FIG. 1 above.

[0061] With more specific reference to the contouring of the distal electrodes 1315, 1316, the distal electrodes may have contoured edges 1338, 1339, respectively, selected to reduce the electric field strength below a target value in the vicinity of the contoured edges 1338, 1339. Such reduction in electric field strength may mitigate electrolysis and / or associated bubble generation within the medium in which the ablation device 1301 is placed (e.g., within a liquid medium such as blood).

[0062] 14 is a close-up view of the electrode 1315 of the ablation device 1301. As shown, the electrode 1315 includes a first edge 1338 and a second edge 1336. The first edge 1338 can be opposite the second edge 1336. For example, the first edge 1338 can be a distal edge and the second edge 1336 can be a proximal edge, or vice versa. The electrode 1315 can be, for example, generally cylindrical (e.g., ring-like) in shape. In some embodiments, the electrode 1315 can include a circular, elliptical, flattened elliptical, or oval cross-section.

[0063] As described above, the first edge 1338 can include a contoured pattern. For example, the edge 1338 can have at least one peak and at least one valley. For example, a peak point P located on the edge 1338 can be formed. P and the distance H between the nearest point p2 located on the edge 1336 P is a valley point P located on the edge 1338. V and the corresponding distance H between the associated closest point p1 located on the edge 1336 V In one embodiment, the point P P and point P V can be connected by a smooth curve without discontinuities, but in an alternative embodiment, the points P P and point P V may be connected by a curve containing one or more discontinuities, and / or a point P P and point P V One or both of may be discontinuities.

[0064] Edges 1336 and 1338 as shown in FIG. 14 are exemplary only and other contoured edges may be used. For example, edge 1336 may be contoured similarly to edge 1338. In some embodiments, the contours of edges 1336 and 1338 may include multiple peaks and valleys. For example, the contour of edge 1338 may include a repeating pattern, such as, for example, a sinusoidal pattern. In some embodiments, edges 1336 and 1338 may or may not be symmetrical with respect to one another and / or different portions of edges 1336 and 1338 may be symmetrical with respect to other portions of edges 1336 and 1338.

[0065] To illustrate the local effect of contoured electrodes on the electric field, Figures 15A and 15B depict two arrangements of electrodes (e.g., on adjacent splines). Figure 15A is a schematic diagram of electrodes 1210A, 1210B arranged on respective parallel splines 1211A, 1211B (e.g., parallel splines 1211A and 1211B may be approximations of the splines of ablation device 110 in a basket configuration). Electrodes 1210A, 1210B may be ring electrodes. A first electrode 1210A may be mounted on the first spline 1211A, and a second electrode 1210B may be mounted on the second spline 1211B. In some embodiments, splines 1211A and 1211B may be constructed from a polymeric material. In demonstrating a computational model of the electric field generated by the electrodes, the electrodes may be surrounded by a blood pool and a potential difference of about 1 kV may be applied across the electrodes 1210A, 1210B. In Figs. 15A and 15B, the diameter and length (along the longitudinal axes 1201A and 1201B) of the electrodes 1210A, 1210B, respectively, are the same. As shown, the electrodes 1210A, 1210B do not include contoured edges. In particular, the electrode 1210A includes a first edge 1213A and a second edge 1215A that are not contoured, and the electrode 1210B includes a first edge 1213B and a second edge 1215B that are not contoured.

[0066] FIG. 15B is a schematic diagram of electrodes 1220A, 1220B disposed on parallel splines 1221A, 1221B (e.g., parallel splines 1221A and 1221B may be approximations of the splines of ablation device 110 in a basket configuration). Electrode 1220A has an upper edge contour (first edge) 1223A, and electrode 1220B has an upper edge contour (first edge) 1223B. Each of edges 1223A, 1223B may have a single valley and, for illustrative purposes, a tangent discontinuity at the crest. In other embodiments, the edge contour may be continuous at the crest. Electrodes 1220A, 1220B have uncontoured lower edges 1225A, 1225B. In Figure 15B, the diameter of the electrodes 1220A, 1220B and the length of the electrodes 1220A, 1220B (along the longitudinal axis of each spline 1221A, 1221B) are the same for the two electrodes 1220A, 1220B, respectively. In demonstrating a computational model of the electric field generated by the electrodes, the electrodes 1220A, 1220B are surrounded by a blood pool and a potential difference of about 1 kV may be applied across the electrodes 1220A, 1220B.

[0067] FIG. 16 is a graph showing the electric field intensity along the lines 1201A, 1201B of FIG. 15A and FIG. 15B. The line 1201A may be an imaginary line extending parallel to the longitudinal axis of the spline 1211A, and the line 1201B may be an imaginary line extending parallel to the longitudinal axis of the spline 1221A. The lines 1201A, 1201B may be equal in length and approximately 600 μm. As mentioned above, to demonstrate the electric field generated by the electrodes, it can be assumed that the electrodes 1210A, 1210B, 1220A, 1220B are placed in a conductive medium (e.g., a blood pool) and a potential difference of approximately 1 kV is applied between the pair of electrodes 1210A, 1210B and between the pair of electrodes 1220A, 1220B. Figure 16 shows the difference in electric field strength along lines 1201A, 1201B as a result of different electrode geometries. In Figure 16, the horizontal axis originates at the interface between the electrode and the spline material (e.g., the electrode-polymer interface) and runs longitudinally parallel to the polymer surface of each spline.

[0068] As shown in FIG. 16, plot line 1220 represents the electric field intensity for electrodes 1210A and 1210B with uncontoured edges 1213A and 1213B, and plot line 1222 represents the electric field intensity for electrodes 1221A and 1221B with contoured edges 1223A and 1223B. As shown in FIG. 16, the contoured electrodes have a smaller electric field intensity near the electrode-spline interface (e.g., electrode-polymer interface) than the uncontoured electrodes. Furthermore, the gradient or drop-off in the electric field intensity is less steep for the contoured electrodes than the uncontoured electrodes. This relationship generally applies to uncontoured electrode geometries versus other contoured edge geometries as described herein. Thus, the systems, devices, and methods described herein, including electrodes with contoured edges, as depicted in FIG. 16, can reduce the electric field strength at the contoured edges of the electrodes and can reduce the drop in electric field strength, both of which can improve the safe delivery of irreversible electroporation in medical applications (e.g., cardiac ablation procedures).

[0069] In some embodiments, multiple electrodes disposed on a shaft or spline can each have an electrode with a contoured edge. Figures 17A and 17B show examples of ablation devices 1701 and 1701' with respective electrodes 1711, 1712, and 1711', 1712', according to an embodiment. In use, electrodes 1711, 1712 can be energized as an electrode pair, and similarly electrodes 1711', 1712' can be energized as an electrode pair, to deliver pulsed electric field ablation. Electrodes 1711, 1712, 1711', 1712' can include contoured edges. As depicted in Figure 17A, electrodes 1711, 1712 can have synchronous contoured edges, i.e., a valley (e.g., valley V1) of electrode 1711 can be synchronous with a peak (e.g., peak P1) of electrode 1712 along direction 1730. In an alternative configuration, electrodes 1711', 1712' may have contoured edges that are asynchronous, as shown in FIG. 17B, i.e., the valley (e.g., valley V2) of electrode 1711' is synchronous with the crest (e.g., crest P2) of electrode 1712' along direction 1730'.

[0070] FIG. 18 shows schematic diagrams of adjacent electrodes with and without contoured edges and plots of the respective electric field strengths between the adjacent electrodes. In particular, two adjacent electrodes 1510A and 1510B with respective uncontoured edges 1521A and 1521B are disposed on a shaft or spline 1501A, and two adjacent electrodes 1511A and 1511B with respective contoured edges 1523A and 1523B are disposed on a shaft or spline 1501B. Plots 1530 and 1532 exemplarily show the difference in electric field strength along the longitudinal axis of the shafts 1501A and 1501B in the space between the adjacent electrodes 1510A, 1510B, 1511A, 1511B. As shown, the contoured electrodes 1511A and 1511B can have a smaller electric field strength near the electrode-polymer interface than the uncontoured electrodes 1510A and 1510B. Furthermore, the gradient or drop in electric field strength is less steep for the contoured electrodes 1511A, 1511B than for the non-contoured electrodes 1510A, 1510B.

[0071] method Also provided in accordance with disclosed embodiments are methods for ablating tissue. In some embodiments, the methods include delivering an ablation device to a chamber of a patient's heart, deploying the ablation device (e.g., positioning the device proximate a target site, deploying the device, etc.), and delivering a pulsed waveform to the ablation device such that the ablation device generates a pulsed electric field to ablate tissue.

[0072] In various embodiments, the system 100 may be used to ablate tissue using various methods described herein. In an exemplary embodiment, tissue ablation is performed in or near one or more heart chambers using the systems and devices described herein. In an embodiment, the heart chamber may be the left atrium and may include its associated pulmonary veins, although the devices and methods described herein may be used in other heart chambers. Generally, one or more catheters may be advanced through the vasculature to a target location in a minimally invasive manner. For example, an ablation device may be advanced through the vasculature over a guidewire and through a deflectable sheath. The sheath may be configured to deflect and aid in guiding the focal ablation catheter through the vasculature and one or more predetermined targets (e.g., pulmonary vein ostia). A dilator may be advanced over the guidewire and configured for formation and dilation of a transseptal opening during and / or prior to use. The methods described herein include introducing and positioning an ablation device (e.g., an ablation device) in contact with one or more pulmonary vein ostia or antral regions. Optionally, pacing signals may be delivered to the heart using a cardiac stimulator (e.g., a cardiac stimulator) and / or cardiac activity may be measured. Spatial characteristics (e.g., location, orientation, configuration) of the ablation device and tissue may be determined and used to generate a predicted ablation zone and / or tissue map for display. Pulse waveforms may be delivered by one or more electrodes of the ablation device to ablate the tissue. The tissue map, including the tissue to be ablated and the predicted ablation zone, may be updated in real time on the display as the device is navigated through the tissue and additional pulse waveforms are delivered to the tissue.

[0073] In some embodiments, the ablation energy may be delivered synchronously with cardiac pacing. In some embodiments, the voltage pulse waveforms described herein may be applied during the refractory period of the cardiac cycle so as not to disrupt the sinus rhythm of the heart. Alternatively, the ablation energy may be delivered asynchronously.

[0074] FIG. 2 is an exemplary process 200 of tissue ablation. Optional steps of the process 200 are shown in FIG. 2 with dashed lines. The process 200 includes, in step 202, the introduction of a device (e.g., an ablation device) into the endocardial space of the heart. In some embodiments, the device may be advanced to be placed in contact with the pulmonary vein ostium. For example, the electrodes of the ablation device may form a generally circular arrangement of electrodes that are placed in contact with the inner radial surface at the pulmonary vein ostium. In some embodiments, the electrodes of the ablation device may be placed near or adjacent to the endocardial surface of the heart. Optionally, a portion of the ablation device may be deployed (e.g., a spline is deployed into a basket or a balloon is expanded). Optionally, in step 206, a pacing signal may be generated for cardiac stimulation of the heart. The pacing signal may then be applied to the heart in step 208. For example, the heart may be electrically paced with a cardiac stimulator to ensure pacing capture and establish periodicity and predictability of the cardiac cycle. One or more of an atrial pacing and a ventricular pacing may be applied optionally. In step 210, an indication of a pacing signal may be sent to a signal generator. A time window within the refractory period of the cardiac cycle during which one or more voltage pulse waveforms may be delivered may then be defined. In some embodiments, the refractory time window may follow the pacing signal. For example, a common refractory time window may be between both the atrial refractory time window and the ventricular refractory time window.

[0075] The pulse waveform may be generated synchronously with the pacing signal, for example, at step 212, if a pacing signal is employed. For example, the voltage pulse waveform may be applied at a refractory time window. In some embodiments, the pulse waveform may be generated with a time offset relative to the indication of the pacing signal. For example, the start of the refractory time window may be offset from the pacing signal by a time offset. The voltage pulse waveform may be applied over a series of heartbeats spanning a corresponding common refractory time window. In other embodiments, the pulse waveform may be generated and applied asynchronously. The generated pulse waveform may be delivered to tissue at step 214. In some embodiments, the pulse waveform may be delivered to a pulmonary vein ostium of the patient's heart via one or more splines of a set of splines of the ablation device. In other embodiments, the voltage pulse waveform as described herein may be selectively delivered to a subset of electrodes, such as an anode-cathode subset, for ablation and isolation of the pulmonary veins. For example, a first electrode of the group of electrodes may be configured as an anode and a second electrode of the group of electrodes may be configured as a cathode. These steps may be repeated for the desired number of pulmonary vein ostia or cavity areas to be ablated (e.g., one, two, three, four or more ostia).In an alternative embodiment, the ablation pulse waveform may be delivered without a pacing signal, i.e., asynchronously.

[0076] It will be understood that the examples and descriptions in this disclosure are for illustrative purposes, and that deviations and variations, such as the number of splines, the number of electrodes, or a variety of focal ablation devices, such as linear ablation catheters, can be constructed and deployed in accordance with the teachings herein without departing from the scope of the invention.

[0077] As used herein, the terms "about" and / or "approximately", when used in conjunction with numerical values ​​and / or ranges, generally refer to numerical values ​​and / or ranges that are close to the recited numerical values ​​and / or ranges. In some cases, the terms "about" and "approximately" may mean within ±10% of the stated value. For example, in some instances, "about 100 [units]" may mean within ±10% of 100 (e.g., 90 to 110). The terms "about" and "approximately" may be used interchangeably.

[0078] Some embodiments described herein relate to computer storage products having a non-transitory computer-readable medium (which may also be referred to as a non-transitory processor-readable medium) having instructions or computer code for performing various computer-implemented operations. The computer-readable medium (or processor-readable medium) is non-transitory in the sense that it does not include a transitory propagating signal itself (e.g., a propagating electromagnetic wave that carries information over a transmission medium such as space or a cable). The medium and the computer code (which may also be referred to as code or algorithms) may be designed and constructed for a specific purpose or purposes. Examples of non-transitory computer readable media include, but are not limited to, magnetic storage media such as hard disks, floppy disks, and magnetic tapes, optical storage media such as compact disks / digital video disks (CD / DVD), compact disk read only memory (CD-ROM), and holographic devices, magneto-optical storage media such as optical disks, carrier wave signal processing modules, and hardware devices specifically configured to store and execute program code, such as application specific integrated circuits (ASICs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), read only memories (ROMs), and random access memory (RAM) devices. Other embodiments described herein relate to computer program products that may include, for example, the instructions and / or computer code disclosed herein.

[0079] The systems, devices, and / or methods described herein may be performed by software (executed on hardware), hardware, or a combination thereof. Hardware modules may include, for example, general-purpose processors (or microprocessors or microcontrollers), field programmable gate arrays (FPGAs), and / or application-specific integrated circuits (ASICs). Software modules (executed on hardware) may be expressed in various software languages ​​(e.g., computer code), including C, C++, Java, Ruby, Visual Basic, and / or other object-oriented, procedural, or other programming languages ​​and development tools. Examples of computer code include, but are not limited to, microcode or microinstructions, machine instructions such as those generated by a compiler, code used to generate web services, and files containing high-level instructions executed by a computer using an interpreter. Further examples of computer code include, but are not limited to, control signals, encryption code, and compression code.

[0080] The specific examples and descriptions herein are exemplary in nature and embodiments may be developed by those skilled in the art based on the teachings herein without departing from the scope of the invention.

Claims

Claim 1. An apparatus comprising: a linear shaft defining a longitudinal axis; and a plurality of electrodes disposed at a distal portion of the linear shaft, wherein the plurality of electrodes are configured to generate an electric field for excising tissue, and the plurality of electrodes include: a tip electrode disposed at a distal end of the linear shaft, the tip electrode including a first contoured edge; and a set of proximal electrodes disposed proximal to the tip electrode, wherein the set of proximal electrodes includes a contoured electrode having a second contoured edge, and the first and second contoured edges each have at least one concave or convex portion. An apparatus. Claim 2. The apparatus of claim 1, wherein each of the first and second contoured edges is configured to reduce an electric field strength at an interface between the contoured edge and the linear shaft. Claim 3. The apparatus of claim 2, wherein each of the first and second contoured edges is configured to reduce a drop in electric field strength in a direction extending away from the contoured edge along the longitudinal axis of the linear shaft. Claim 4. The apparatus according to any one of claims 1 to 3, wherein the first contoured edge is a proximal edge of the tip electrode, and the second contoured edge is a distal edge of the proximal electrode closest to the tip electrode among the set of proximal electrodes. Claim 5. The apparatus of claim 4, wherein each of the first and second contoured edges has a plurality of peaks and valleys. Claim 6. The apparatus of claim 5, wherein one or more of the plurality of peaks and valleys of the first contoured edge are aligned with one or more of the plurality of peaks and valleys of the second contoured edge. Claim 7. The apparatus according to any one of claims 1 to 6, wherein the distal tip electrode is configured to be energized with a first polarity, and the proximal electrodes are configured to be energized with a second polarity opposite to the first polarity to form an electrode pair for generating the electric field.

8. The apparatus according to any one of claims 1 to 7, further comprising a sleeve that can be arranged to cover a part of the linear shaft, wherein the sleeve is movable relative to the linear shaft so as to expose at least a subset of the set of the proximal electrodes so that the electric field can be generated using the subset of the proximal electrodes.

9. The apparatus according to claim 1, wherein the at least one concave or convex portion includes a plurality of concave or convex portions.

10. The apparatus according to claim 1, wherein the radius of curvature of the at least one concave or convex portion is at least 10 μm and less than 50,000 μm.

11. The apparatus according to claim 1, wherein the radius of curvature of the first concave or convex portion is different from the radius of curvature of the second concave or convex portion.

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