Systems, devices, and methods for focal ablation

Abstract

To provide systems, devices, and methods for electroporation ablation therapy.SOLUTION: A device may include a linear shaft including a distal portion positionable near a tissue wall. The linear shaft can be configured to deflect to position the distal portion near the tissue wall. The device can include a plurality of electrodes disposed on the distal portion of the linear shaft, whereas the plurality of electrodes are configured to generate a pulsed electric field that produces an ablation zone in the tissue wall having a depth that is independent of an orientation of the distal portion relative to the tissue wall.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to systems, devices and methods for localized ablation. [Background technology]

[0002] While the generation of pulsed electric fields for tissue treatment has been moving from laboratory to clinical applications over the past 20 years, the effects of short pulses of high voltage and large electric fields on tissues have been studied for over 40 years. The application of short-term high direct current voltages to tissues can generate localized high electric fields, typically in the range of hundreds of volts per centimeter, that can disrupt cell membranes by generating pores in the membrane. Although the exact mechanism of this electrically driven pore generation or electroporation is still being investigated, it is believed that the application of relatively short and large electric fields creates instability in the lipid bilayer of the cell membrane, generating a localized distribution of gaps or pores in the cell membrane. This electroporation can be irreversible such that the pores do not close but remain open if the electric field applied to the membrane is greater than a threshold value, thereby allowing the exchange of biomolecular material across the membrane, leading to necrosis and / or apoptosis (cell death). The surrounding tissue can then heal naturally.

[0003] Although pulsed direct current voltage can stimulate electroporation under appropriate circumstances, there remains an unmet need for a thin, flexible, atraumatic device that effectively delivers high direct current voltage electroporation ablation therapy selectively to endocardial tissue within the region of interest while minimizing damage to healthy tissue. Summary of the Invention

[0004] Described herein are systems, devices, and methods for ablating tissue by irreversible electroporation. In general, a device (e.g., a catheter) for applying pulsed electric field ablation to soft tissue (e.g., cardiac tissue) may include a linear flexible body having multiple distally disposed electrodes. In some embodiments, the device may be used to form a localized ablation lesion.

[0005] In some embodiments, the system includes an ablation device and a signal generator. The ablation device includes a linear shaft including a distal portion positionable near a tissue wall, the linear shaft configured to deflect to position the distal portion near the tissue wall, a plurality of electrodes disposed on the distal portion, the plurality of electrodes including a set of distal electrodes and a set of proximal electrodes disposed proximal to the set of distal electrodes, each proximal electrode from the set of proximal electrodes being spaced a first length of the linear shaft from an adjacent proximal electrode from the set of proximal electrodes, and a most distal proximal electrode from the set of proximal electrodes being spaced a second length of the linear shaft from a most proximal distal electrode from the set of distal electrodes, and a plurality of leads coupled to the plurality of electrodes, each lead having insulation configured to withstand a potential difference of at least about 700 V without dielectric breakdown. The signal generator is operably coupled to the ablation device and configured to activate at least one distal electrode from a set of distal electrodes having a first polarity and a set of proximal electrodes having a second polarity opposite the first polarity such that the multiple electrodes generate pulsed electric field energy that produces an ablation zone within the tissue wall having a depth independent of an orientation of the distal portion relative to the tissue wall.

[0006] In some embodiments, the device includes a linear shaft including a distal portion positionable near a tissue wall, the linear shaft configured to be deflected to position the distal portion near the tissue wall, a plurality of electrodes disposed on the distal portion configured to generate a pulsed electric field in the tissue wall that produces an ablation zone having a depth independent of an orientation of the distal portion relative to the tissue wall, a set of distal electrodes including a distal tip electrode disposed on a tip of the linear shaft, and a set of proximal electrodes disposed proximal to the set of distal electrodes, each proximal electrode from the set of proximal electrodes being spaced apart from an adjacent proximal electrode from the set of proximal electrodes by a first length of the linear shaft, ... a set of proximal electrodes, a most distal proximal electrode from the set of proximal electrodes being spaced from a most proximal distal electrode from the set of distal electrodes by a second length of the linear shaft, the first length of the linear shaft being less than the second length of the linear shaft; and a plurality of leads coupled to the plurality of electrodes, each lead from the plurality of leads configured to deliver a voltage output having an amplitude of at least 700 V to the plurality of electrodes (1) without dielectric breakdown of its corresponding insulation, and (2) such that when the set of distal electrodes having a first polarity is activated and the set of proximal electrodes having a second polarity opposite the first polarity are activated, the plurality of leads collectively generate a pulsed electric field.

[0007] In some embodiments, the method includes positioning a linear shaft of an ablation device within a cardiac cavity of a subject's heart such that a distal portion of the linear shaft is proximate a tissue wall, the ablation device including a plurality of electrodes disposed on the distal portion, the plurality of electrodes including a set of distal electrodes and a set of proximal electrodes, each proximal electrode from the set of proximal electrodes being spaced apart from an adjacent proximal electrode from the set of proximal electrodes by a first length of the linear shaft, and a most distal proximal electrode from the set of proximal electrodes being spaced apart from a most proximal distal electrode from the set of distal electrodes by a second length of the linear shaft; generating a pulse waveform having a voltage amplitude of at least about 700 V using a signal generator; and delivering a pulse waveform having a first polarity to the set of distal electrodes and a pulse waveform having a second polarity opposite the first polarity to the set of proximal electrodes such that the plurality of electrodes collectively generate a pulsed electric field that produces an ablation zone in the tissue wall having a depth independent of an orientation of the distal portion relative to the tissue wall. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram of an electroporation system, according to an embodiment. [Diagram 2] 1 illustrates a method of tissue ablation according to an embodiment. [Diagram 3] 1 illustrates a method of tissue ablation according to an embodiment. [Figure 4] FIG. 2 shows a schematic diagram of a distal end of an ablation catheter, according to an embodiment. [Diagram 5] 1 illustrates an electric field generated by electrodes of an ablation catheter positioned adjacent tissue, according to an embodiment. [Figure 6] 1 illustrates an electric field generated by electrodes of an ablation catheter positioned adjacent tissue, according to an embodiment. [Figure 7] 1 illustrates an electric field generated by electrodes of an ablation catheter positioned adjacent tissue, according to an embodiment. [Figure 8]1 illustrates an electric field generated by electrodes of an ablation catheter positioned adjacent tissue, according to an embodiment. [Figure 9] 1 is a schematic diagram of a distal end of an ablation catheter, according to an embodiment. [Figure 10] 1 is a schematic diagram of a distal end of an ablation catheter, according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Described herein are systems, devices, and methods for applying pulsed electric fields to ablate tissue by irreversible electroporation. In some embodiments, the systems, devices, and methods described herein can be configured to provide localized ablation. Such systems, devices, and methods can generate controllable ablation zones in tissue independent of orientation, i.e., independent of the orientation of the ablation device (e.g., catheter) generally relative to the tissue surface or tissue wall.

[0010] As used herein, the term "electroporation" refers to the application of an electric field to a cell membrane to change the permeability of the cell membrane to the extracellular environment. As used herein, the term "reversible electroporation" 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 may exhibit the temporary and / or intermittent formation of one or more pores in its cell membrane, which pores close upon removal of the electric field. As used herein, the term "irreversible electroporation" 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 may exhibit the formation of one or more pores in its cell membrane, which persist upon removal of the electric field.

[0011] In general, the systems and devices described herein include one or more ablation devices (e.g., catheters) configured to, for example, ablate tissue within a cardiac chamber (e.g., atrium, ventricle). FIG. 1 illustrates an ablation system (100). The system (100) may include a device (120). The device (120) includes a signal generator (122), a processor (124), a memory (126), and optionally a cardiac stimulator (128). The device (120) may be coupled to the ablation device (110) and, optionally, a pacing device (130).

[0012] The signal generator (122) may be configured to generate a voltage pulse waveform for irreversible electroporation of tissue, such as an endocardial wall. 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), the cardiac stimulator (128), and the pacing device (130) 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 for causing 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.

[0013] In some embodiments, the ablation device (110) may include a catheter configured to receive and / or deliver a pulsed waveform, as described in more detail below. For example, the ablation device (110) may be introduced into an endocardial space of a chamber of the heart and positioned such that one or more electrodes (112) of the ablation device (110) are proximate to a target tissue (e.g., an endocardial wall). The ablation device (110) may then deliver a pulsed waveform to ablate the tissue. In some embodiments, the one or more electrodes (112) of the ablation device (110) may include one or more independently addressable electrodes, as described further below with reference to FIGS. 4-8. Each electrode (112) may include an insulated electrical lead configured to maintain a voltage potential of at least about 500V without dielectric breakdown of the corresponding insulation of the insulated electrical lead. In some embodiments, the insulation of each electrical lead may maintain an electrical potential difference across its thickness of about 200V to about 3,000V without dielectric breakdown.

[0014] In some embodiments, the device (120) may be connected to a pacing device (130). The pacing device (130) may be suitably coupled to a patient (not shown) and configured to receive a cardiac pacing signal generated by an optional cardiac stimulator (128) of the device (120) for cardiac stimulation, for example. An indication of a pacing signal may be transmitted by the cardiac stimulator (128) to the signal generator (122). An indication of a voltage pulse waveform may be selected, calculated, and / or otherwise identified by the processor (124) based on the pacing signal and generated by the signal generator (122). In some embodiments, the signal generator (122) is configured to generate a pulse waveform that is synchronous with the indication of the pacing signal (e.g., within a refractory window associated with an atrial or ventricular pacing signal). For example, in some embodiments, the refractory window may begin approximately immediately (or after a very slight delay) after the ventricular pacing signal and last for a time period of about 250 ms or less thereafter. In such embodiments, the entire pulse waveform may be delivered within this time period.

[0015] In some embodiments, the system (100) may include a tracking system or device (140). The tracking system (140) may be operatively coupled to and / or integrated into the device (120). The tracking system (140) may enable impedance-based tracking and / or electromagnetic tracking of the ablation device (110), particularly the distal portion of the ablation device (110), as the ablation device (110) is navigated through the anatomy. The tracking system (140) may include a field generator (142), which includes a set of transmitters configured to generate a field, e.g., a magnetic field and / or an electric field. For example, the field generator (142) may include a set of electrode patches capable of generating and maintaining an electrical potential difference across a range of frequencies between the set of electrode patches. Alternatively or additionally, the field generator (142) may include a set of transmitter coils configured to generate a time-varying magnetic field. The generated electric and / or magnetic fields may be received as signals (e.g., voltage, current, or both) by a set of sensors (114) located near and / or integrated into the ablation device (110). In one embodiment, the sensors (114) may be electromagnetic sensors integrated into a distal portion of the ablation device (110), such as a distal portion of a catheter. Using the tracked position information, a visual representation of the ablation device (100) may be displayed, for example, within an electroanatomical or anatomical map to provide a spatial context for visualizing the catheter position. Such a visual representation may be generated, for example, by a processor (124) or another processing device coupled to and / or integrated into the device (120) and / or tracking system (140).A suitable example of a tracking system for use with an ablation device is described in U.S. Patent Application Publication No. 16 / 785,392, entitled "METHODS, SYSTEMS, AND APPARATUSES FOR TRACKING ABLATION DEVICES AND GENERATING LESION LINES," filed February 7, 2020, the contents of which are incorporated herein by reference.

[0016] Optionally, the ablation device (110) may include an actuation mechanism (129), such as a knob, lever, or other suitable mechanism for deflecting, manipulating, etc., the ablation device (110) within the anatomy. The actuation mechanism may be controlled by an operator based on the position of a distal portion of the ablation device (110). For example, the operator may control the angle or orientation of a distal portion of the ablation device (110) to steer the ablation device (110) to a particular position based on the tracked position of the ablation device (110) tracked by the tracking system (140).

[0017] 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), etc. 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 a network (not shown) associated with the system. The underlying device technology may be provided in a variety of component types, for example, metal-oxide semiconductor field-effect transistor (MOSFET) technologies such as complementary metal-oxide semiconductor (CMOS), bipolar technologies such as emitter-coupled logic (ECL), polymer technologies (e.g., silicon-conjugated polymer and metal-conjugated polymer metal structures), mixed analog and digital, etc.

[0018] 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, erasable programmable read-only memory (EPROM), electrically erasable read-only memory (EEPROM), read-only memory (ROM), flash memory, etc. The memory (126) may store instructions for causing the processor (124) to execute modules, processes and / or functions associated with the system (100), such as pulse waveform generation and / or cardiac pacing.

[0019] The system (100) may communicate with other devices (not shown), for example, via one or more networks, each of which may be any type of network. 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 connect to a wired network, other carrier voice and data networks, business networks, and personal networks to interface with the Internet. Wired networks are typically applied with copper twisted pair coaxial cables or fiber optic cables. 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). In the following, a network refers to any combination of hybrid wireless, wired, public, and private data networks interconnected, typically via the Internet, to provide an integrated networking and information access solution.

[0020] The ablation systems described herein, such as the system (100) shown in FIG. 1, may be used according to the methods as shown in FIGS. 2 and 3. In some embodiments, the ablation systems may be used to ablate tissue within a cardiac chamber, such as the left atrium. In general, the methods described herein include introducing a device and positioning it adjacent to and / or in contact with an endocardial wall. A pulse waveform may be delivered by one or more electrodes of the device to ablate the tissue. In some embodiments, a cardiac pacing signal may synchronize the delivered pulse waveform with the cardiac cycle. Tissue ablation performed in this manner may be delivered in synchronization with the paced beats and with less energy delivery to reduce damage to healthy tissue. It should be understood that any of the ablation devices described herein may be used to ablate tissue, as appropriate, using the methods described below.

[0021] In some embodiments, the ablation devices described herein may be used for localized ablation of cardiac features / structures identified as causing arrhythmia. Localized ablation may, for example, create punctate lesions that neutralize the rotor while sparing the surrounding tissue. Further details of ablation zones generated using the systems, devices, and methods disclosed herein are described below with reference to Figures 5-8.

[0022] FIG. 2 illustrates an exemplary method (200) of ablating tissue. The method (200) includes, at (202), introducing a device (e.g., ablation device (110)) into the endocardial space of a heart cavity. At (204), the device may be advanced to be positioned adjacent to the tissue. The ablation device may include an electrode (e.g., electrode (112)) positioned adjacent to the tissue. For example, the ablation device may be a linear flexible device including multiple distally positioned electrodes, which may be positioned near or in contact with a tissue surface, such as an endocardial wall within a heart cavity, such as the left or right atrium. The method (200) may include, at (206), either manually or automatically configuring one or more electrodes of the ablation device as an anode and / or a cathode. In some embodiments, the ablation device may include one or more distal electrodes and one or more proximal electrodes, where at least one distal electrode and at least one proximal electrode may be configured as an anode-cathode set. For example, as further described with reference to FIGS. 4-10, the ablation device may include a distal tip electrode and two proximal electrodes, where the distal tip electrode may be paired with the two proximal electrodes to form an anode-cathode set. In another embodiment, the ablation device may have two or less or four or more electrodes, e.g., two, four, five or six electrodes, where the electrodes include a subset of distal and proximal electrodes. In some embodiments, the voltage pulse waveform may be selectively delivered to an electrode set, such as an anode-cathode set for ablation of tissue. For example, the distal tip electrode of the ablation device may be selected as the anode and the proximal electrode of the ablation device may be selected as the cathode, and the voltage pulse waveform is applied between the anode and the cathode.

[0023] Optionally, at (207), the voltage level of the pulse waveform or a portion of the pulse waveform (e.g., the amplitude of one or more voltage pulses) may be set. For example, the voltage level may be increased to create a deeper ablation zone, which may be useful when the tissue is thicker. As a non-limiting set of examples, the amplitude of the individual pulses of the exemplary pulse waveform may be in the range from about 400V, about 1,000V, about 5,000V, about 10,000V, about 15,000V, including all values ​​and subranges therebetween.

[0024] At 208, a pulse waveform may be generated by a signal generator, such as signal generator 122. In some embodiments, the pulse waveform may be a voltage pulse waveform that includes multiple levels of hierarchy, while in other embodiments other waveform implementations may be used. Examples of suitable pulse waveforms including multiple levels of hierarchy are disclosed in International Application PCT / US2016 / 057664, filed October 19, 2016, entitled "SYSTEMS, APPARATUSES AND METHODS FOR DELIVERY OF ABLATIVE ENERGY TO TISSUE," and International Application PCT / US2019 / 031135, filed May 7, 2019, entitled "SYSTEMS, APPARATUSES AND METHODS FOR DELIVERY OF ABLATIVE ENERGY TO TISSUE," each of which is incorporated herein by reference in its entirety. Various hierarchical waveforms may be generated by the signal generators disclosed herein (e.g., signal generator (122)).

[0025] At (210), the generated pulse waveform can be delivered to an anode-cathode electrode set such that the electrode set generates an electric field that ablates tissue. For example, the electrodes of the distal tip ablation catheter can be polarized with a first electrical polarity and the proximal electrodes of the ablation catheter can be polarized with a second electrical polarity opposite the first electrical polarity such that the distal tip electrode and the proximal electrode generate an electric field that can form an ablation lesion. As another example, in an embodiment having four electrodes, the distal pair of electrodes can have one electrical polarity and the proximal pair of electrodes can have an opposite electrical polarity during ablation delivery. Thus, the multiple electrodes collectively generate an electric field for ablation. Further details of such an embodiment are described with reference to Figures 4-10. The spatial morphology of the ablation lesion can have a controlled depth or volume by application of an appropriate waveform and by appropriate voltage levels, electrode geometry and / or electrode pairing, for example, as described herein. In some embodiments, as described further below, one or more voltage pulse waveforms may be applied, for example, over a series of beats during the refractory time window.

[0026] In some embodiments, the voltage pulse waveforms described herein may be applied during the refractory period of the cardiac cycle to avoid disturbance of the sinus rhythm of the heart. FIG. 3 illustrates another exemplary method (300) of ablating tissue. The method (300) may be similar to the method (200) described above, but may include applying a pulse waveform in synchronization with one or more pacing signals. The method (300) includes, at (302), the introduction of a device (e.g., ablation device (110)) into an endocardial space of a cardiac cavity. The device may be advanced to be positioned adjacent to a tissue wall of the heart, for example, an endocardial surface in the left or right atrium. For example, the ablation device may be a linear flexible device including multiple distally disposed electrodes, which may be positioned near or in contact with the endocardial wall. In some embodiments, at (312), a pacing signal may be generated for cardiac stimulation of the heart. The pacing signal may then be applied to the heart at (314). For example, the heart may be electrically paced by a cardiac stimulator (e.g., cardiac stimulator (128)) to ensure pacing capture and establish periodicity and predictability of the cardiac cycle. One or more of atrial pacing and ventricular pacing may be applied. At (316), an indication of a pacing signal may be transmitted to a signal generator. A time window within a refractory period of the cardiac cycle may then be defined. Within the time window, one or more voltage pulse waveforms may be delivered. 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.

[0027] At (308), the pulse waveform may be generated synchronously with the pacing signal. For example, the voltage pulse waveform may be applied within a common refractory time window. In some embodiments, the pulse waveform may be generated with a time lag 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 lag. The voltage pulse waveform may be applied over a series of beats over a corresponding common refractory time window. At (310), the generated pulse waveform may be delivered to an ablation device such that the ablation device generates a pulsed electric field to ablate tissue.

[0028] The methods described herein may be performed using a system including one or more multi-electrode ablation devices. FIG. 4 is a side view of an ablation device (400). The ablation device (400) may include structurally and / or functionally similar components to the ablation device (110), as described above with reference to FIG. 1. The ablation device (400) may be a flexible linear catheter having multiple distally disposed electrodes. The ablation device (400) may include a shaft or body (431) and multiple electrodes (419, 421, 423) including a distal tip electrode (419) and proximal electrodes (421, 423). The multiple electrodes (419, 421, 423) may be located at a distal portion of the body (431). The proximal electrodes (421, 423) are located proximal to the tip electrode (419), and each electrode (419, 421, 423) is separated from the adjacent electrode by a shaft portion (433, 435).

[0029] The electrodes (419, 421, 423) may be positioned adjacent to and / or in contact with tissue, such as endocardial tissue. However, it should be understood that while the electrodes (419, 421, 423) may be positioned to touch endocardial tissue, the electrodes (419, 421, 423) do not have to contact endocardial tissue to form an ablation zone as described herein.

[0030] One or more of the electrodes (419, 421, 423) may be independently addressable electrodes. In some embodiments, a subset of the electrodes (419, 421, 423) may be wired together. For example, the proximal electrodes (421, 423) may be wired together and the distal tip electrode (419) may be independently addressable or separately wired from the proximal electrodes (421, 423). One or more of the electrodes (419, 421, 423) may be coupled to an insulated electrical lead configured to maintain a voltage potential of at least about 500V without dielectric breakdown of the corresponding insulation of the insulated electrical lead. In other embodiments, the insulation of each electrical lead may maintain an electrical potential difference of about 200V to about 2000V (including all subranges and values ​​therebetween) across its thickness without dielectric breakdown. Body (431) may, for example, include an insulated electrical lead for each of electrodes (419, 421, 423) within a lumen defined therein.

[0031] In some embodiments, the shaft portions (433, 435) separating the electrodes (419, 421, 423) may be flexible so that the ablation device (400) may be deflected, for example, to be positioned adjacent to a target tissue (e.g., soft tissue in the heart). In other embodiments, one or both of the intermediate shaft portions (433, 435) may be rigid or semi-rigid. A pull wire (440) may be disposed within the ablation device (400) to deflect the ablation device (400). The pull wire (440) may be attached to a rigid portion of the body (431), for example, where the electrodes (419, 421, 423) are located, and may be pulled to deflect a portion of the body (431) proximal to the attachment location. In some embodiments, the shaft portions (433, 435) are configured to deflect with a more proximal portion of the body (440). The pull wires (440) may be attached to a handle (not shown) that may be used to control the deflection of the body (431) located at the proximal end of the ablation device (400). The handle may include a mechanism for deflecting or manipulating a distal portion of the ablation device (400), for example, by tension on the pull wires (440).

[0032] According to the methods described herein, the ablation device (400) can be used to create ablation zones in tissue through application of a high voltage waveform of pulsed electric field ablation, whereby regions of cauterized tissue are created by irreversible electroporation. The ablation device (400) can be used in clinical applications including, for example, cardiac ablation for the treatment of cardiac arrhythmias. In some embodiments, the ablation device (400) can create localized or focal ablation zones that can be about 5 mm to about 15 mm in diameter and about 1 mm to about 6 mm in depth.

[0033] In some embodiments, one or more pulse waveforms may be applied between the electrodes (419, 421, 423) comprised of an anode and cathode set. For example, the distal tip electrode (419) may be electrically paired with the proximal electrodes (421, 423). A signal generator (e.g., signal generator (122)) may be used to deliver the pulse waveforms to the electrodes (419, 421, 423) such that the tip electrode (419) is polarized with a first electrical polarity and the two proximal electrodes (421, 423) are both polarized with a second electrical polarity opposite the first electrical polarity. In some embodiments, the pulse waveform may be a hierarchical waveform as described above, while in other embodiments other waveform structures may be used. When the electrodes (419, 421, 423) are paired in this manner and energized with a voltage pulse waveform of appropriate amplitude, the electrodes (419, 421, 423) can generate an ablation zone having a depth that is nearly independent of the orientation of the electrodes (419, 421, 423) relative to the tissue, as will be further described with reference to Figures 5-8.

[0034] In some embodiments, the body (431) may have a diameter of about 1 mm to about 5 mm (including all subranges and values ​​therebetween). For example, in some embodiments, the body (431) may have a diameter of about 4 French (1.33 mm) to about 15 French (5 mm). In some embodiments, the distal tip electrode (419) may have a length L1 in the range of about 1 mm to about 8 mm. In some embodiments, the proximal electrodes (421, 423) may each have a length L2 in the range of about 1 mm to about 6 mm. In some embodiments, the distal tip electrode (419) may have a length L1 that is greater than the length L2 of the proximal electrodes (421, 423). In some embodiments, the proximal electrodes (421, 423) may have variable lengths. In some embodiments, the shaft portions (433, 435) that separate adjacent electrodes (419, 421, 423) may each have a length in the range of about 1 mm to about 10 mm. In some embodiments, a distance D1 separating the tip electrode (419) from the first proximal electrode (423) can be greater than a distance D2 separating the first proximal electrode (423) from the second proximal electrode (421). Alternatively, the distances D1 and D2 separating adjacent electrodes (419, 421, 423) can be equal to one another, or the distance D2 can be greater than the distance D1.

[0035] Although the ablation device (400) is shown with a single distal tip electrode (419) and two proximal electrodes (421, 423), it will be understood that the ablation device (400) may include an additional number of distal and / or proximal electrodes. For example, in an alternative configuration, the ablation device (400) may include three or more proximal electrodes, and a subset of the proximal electrodes (e.g., two of the proximal electrodes) may be selected to generate a pulsed electric field.

[0036] FIG. 9 illustrates a schematic of a distal portion of an ablation device (900). The ablation device (900) may be and / or may include components that are structurally and / or functionally similar to other ablation devices described herein, including, for example, the ablation device (110) described above with reference to FIG. 1. The ablation device (900) may be a flexible linear catheter having a distal portion (911) that includes a set of distal electrodes (918, 920) and a set of proximal electrodes (913, 915). The set of distal electrodes (918, 920) may be separated from the set of proximal electrodes (913, 915) by a shaft portion (924). In some embodiments, the shaft portion (924) may be flexible, and in alternative embodiments, the shaft portion (924) may be rigid or generally rigid. A pull wire (940) may be disposed within the ablation device (900) to deflect the ablation device (900). The pull wire (940) may be coupled to an internal location within the shaft of the ablation device (900), such as between the proximal electrode (913) and the distal electrode (920). For example, the pull wire (940) may be attached proximal to the proximal electrode (913), proximal to the distal electrode (918), between the distal electrodes (918, 920), etc. In some embodiments, the pull wire (940) may be coupled to a handle mechanism or actuator (not shown) that allows a user to manipulate an actuation element (e.g., a rocker, knob, lever, or other suitable mechanism) to deflect the distal portion (911) of the ablation device (900). Depending on where the pull wire (940) is coupled to the shaft (e.g., distal or proximal to the shaft portion (924)) and the flexibility of the shaft portion (924), when a portion of the shaft is deflected using the pull wire (940), the shaft portion (924) may or may not be deflected.

[0037] In some embodiments, one or more of the electrodes (913, 915, 918, 920) may be independently addressable electrodes, with individual insulated wires or leads coupled to each independently addressable electrode. In some embodiments, a subset of the electrodes (913, 915, 918, 920) may be wired together. For example, the proximal electrodes (913, 915) may be wired together using a single lead, and the distal electrodes (918, 920) may be wired together using a single lead. Alternatively, the distal tip electrode (920) may be independently addressable and wired by its own lead, the distal electrode (918) may be wired by its own lead, and the proximal electrodes (913, 915) may be wired together by a single lead. The insulation covering each lead may have sufficient dielectric strength to withstand a potential difference across its thickness of about 200 V to about 2000 V (including all subranges and values ​​therebetween) without dielectric breakdown. In one embodiment, the insulation covering each lead may have sufficient dielectric strength to withstand a potential difference of at least about 700 V without dielectric breakdown.

[0038] Optionally, a sensor (950) may be incorporated into the distal portion (911) of the catheter. One or more separate leads (not shown) are attached to the sensor (950). The sensor (950) may be used, for example, to enable tracking of the position, orientation, etc. of the ablation device (900) within an anatomical structure (e.g., a heart cavity). For example, the sensor (950) may be an electromagnetic sensor that can receive an electromagnetic signal from a transmitter coil associated with a position tracking system (e.g., tracking system (140)). The transmitter coil may be configured to generate a time-varying field that is received as a signal (e.g., voltage, current, or both) by the sensor (950). In some embodiments, one or more of the electrodes (913, 915, 918, 920) or another electrode (not shown) may be used to receive electrocardiogram data. The electrocardiogram data may provide diagnostic information or may be used to assess position. For example, the distal electrodes (918, 920) may be used to collect ECG data. The ECG data may be displayed as a bipolar (differential) signal on a display associated with the ECG system. Additionally or alternatively, the electrodes (913, 915, 918, 920) may be used to sense signals from an impedance localization system to track the ablation device (900). Using the tracked location information, a visual representation of the ablation device (900) may be displayed within an electroanatomical or anatomical map, for example, to provide a spatial context for visualizing the catheter position.

[0039] According to the methods described herein, an ablation zone can be created in tissue by application of a high voltage waveform of pulsed electric field ablation using the ablation device (900), whereby a region of ablated tissue is created by irreversible electroporation. The ablation device (900) can be operatively coupled to a signal generator (e.g., signal generator (122)) and used to deliver irreversible electroporation ablation to a tissue site. The signal generator can generate one or more pulse waveforms that are applied between electrodes (913, 915, 918, 920) configured as an anode and cathode set. For example, a set of distal electrodes (918, 920) and a set of proximal electrodes (913, 915) can be paired as an anode-cathode pair to create a lesion by irreversible electroporation. In other words, the set of distal electrodes (918, 920) may be actuated with a first polarity and the set of proximal electrodes (913, 915) of opposite polarity may be actuated with a second polarity such that the electrodes (913, 915, 918, 920) collectively generate an electric field that ablates the tissue site. When the electrodes (913, 915, 918, 920) are paired in this manner and energized with an appropriate voltage pulse waveform of appropriate amplitude, the electrodes (913, 915, 918, 920) may generate an ablation zone having a depth that is approximately independent of the orientation of the electrodes (913, 915, 918, 920) relative to the tissue, as will be further described with reference to Figures 5-8. Such a pairing scheme is capable of generating ablation lesions having a depth that is approximately independent of the orientation of the catheter.

[0040] In some embodiments, the shaft of the ablation device (900) can have a diameter of about 4 French (1.33 mm) to about 15 French (5 mm). In some embodiments, each distal electrode (918, 920) can have the same length, e.g., length L1', and each proximal electrode (913, 915) can have the same length, e.g., length L2'. In other embodiments, the lengths of at least some of the distal electrodes can be different from each other, or the lengths of at least some of the proximal electrodes can be different from each other. The length L1' of each distal electrode (918, 920) can be approximately equal to the length L2' of each proximal electrode, can be greater than the length L2' of each proximal electrode, or can be less than the length L2' of each proximal electrode. In some embodiments, each distal electrode (918, 920) can have a different length, and / or each proximal electrode (913, 915) can have a different length. In some embodiments, the total length of the distal electrodes (918, 920) may be approximately equal to the total length of the proximal electrodes (913, 915), may be greater than the total length of the proximal electrodes (913, 915), or may be less than the total length of the proximal electrodes (913, 915). The proximal electrodes (913, 915) may be separated from one another by a distance D2', and the distal electrodes (918, 920) may be separated from one another by a distance D3'. In some embodiments, the distance D2' separating the proximal electrodes (913, 915) may be approximately equal to the distance D3' separating the distal electrodes (918, 920), may be greater than the distance D3' separating the distal electrodes (918, 920), or may be less than the distance D3' separating the distal electrodes (918, 920). In some embodiments, distance D2' and distance D3' can be less than distance D1' separating distal electrode (918) from proximal electrode (915). Distances D1', D2', and D3' can be generally in the range of 0.5 mm to 12 mm. In some embodiments, ratio D2' / D1' can be in the range of 1 to 20.

[0041] FIG. 10 illustrates a schematic of a distal portion of an ablation device (1000). The ablation device (1000) may be and / or include components structurally and / or functionally similar to other ablation devices described herein. The ablation device (1000) may be a flexible linear catheter having a distal portion (1011) including a set of distal electrodes (1018, 1020, 1022) and a set of proximal electrodes (1013, 1015). The set of distal electrodes (1018, 1020, 1022) may be separated from the set of proximal electrodes (1013, 1015) by a shaft portion (1024). In some embodiments, the shaft portion (1024) may be flexible, and in alternative embodiments, the shaft portion (1024) may be rigid or generally rigid. The pull wire 1040 can be disposed within the ablation device 1000 to deflect the ablation device 1000. The pull wire 1040 can be coupled to an internal location within the shaft of the ablation device 1000, such as between the proximal electrode 1013 and the distal electrode 1022. For example, the pull wire 1040 can be attached proximal to the proximal electrode 1013, proximal to the distal electrode 1018, between the distal electrodes 1018, 1022, etc. In some embodiments, the pull wire 1040 can be coupled to a handle mechanism or actuator (not shown) that allows a user to manipulate an actuation element (e.g., a rocker, knob, lever, or other suitable mechanism) to deflect the distal portion 1011 of the ablation device 1000. Depending on the location where the pull wire (1040) is coupled to the shaft (e.g., distal or proximal to the shaft portion (1024)) and the flexibility of the shaft portion (1024), when a portion of the shaft is deflected using the pull wire (1040), the shaft portion (1024) may or may not be deflected.

[0042] In some embodiments, one or more of the electrodes (1013, 1015, 1018, 1020, 1022) may be independently addressable electrodes, with individual insulated wires or leads coupled to each electrode. In some embodiments, a subset of the electrodes (1013, 1015, 1018, 1020, 1022) may be wired together. For example, the proximal electrodes (1013, 1015) may be wired together using a single lead, and the distal electrodes (1018, 1020, 1022) may be wired together using a single lead. Alternatively, the distal tip electrode (1022) may be independently addressable and wired by its own lead, the distal electrodes (1018, 1020) may be wired together by a single lead, and the proximal electrodes (1013, 1015) may be wired together by a single lead. The insulation covering each lead may have sufficient dielectric strength to withstand a potential difference across its thickness of about 200 V to about 2000 V (including all subranges and values ​​therebetween) without dielectric breakdown. In one embodiment, the insulation covering each lead may have sufficient dielectric strength to withstand a potential difference of at least about 700 V without dielectric breakdown.

[0043] Optionally, the sensor (1050) may be incorporated into the distal portion (1011) of the catheter. One or more separate leads (not shown) are attached to the sensor (1050). The sensor (1050) may be used, for example, to enable tracking of the position, orientation, etc. of the ablation device (1000) within an anatomical structure (e.g., a heart cavity). For example, the sensor (1050) may be an electromagnetic sensor capable of receiving an electromagnetic signal from a transmitter coil associated with a position tracking system (e.g., tracking system (140)). In some embodiments, one or more of the electrodes (1013, 1015, 1018, 1020, 1022) or another electrode (not shown) may be used to receive ECG data. The ECG data may provide diagnostic information or may be used to assess position. For example, the distal electrodes (1018, 1020) may be used to collect ECG data. The ECG data may be displayed as a bipolar (differential) signal on a display associated with the ECG system. Additionally or alternatively, the electrodes (1013, 1015, 1018, 1020, 1022) can be used to sense signals from an impedance localization system to track the ablation device (1000). Using the tracked position information, a visual representation of the ablation device (1000) can be displayed, for example, within an electroanatomical or anatomical map to provide a spatial context for visualizing the catheter position.

[0044] According to the methods described herein, the ablation device (1000) can be used to create an ablation zone in tissue by application of a high voltage waveform of pulsed electric field ablation, whereby a region of ablated tissue is created by irreversible electroporation. The ablation device (1000) can be operatively coupled to a signal generator (e.g., signal generator (122)) and used to deliver irreversible electroporation ablation to a tissue site. The signal generator can generate one or more pulse waveforms that are applied between electrodes (1013, 1015, 1018, 1020, 1022) configured as an anode and cathode set. For example, the set of distal electrodes (1018, 1020, 1022) and the set of proximal electrodes (1013, 1015) can be paired as an anode-cathode pair to create a lesion by irreversible electroporation. When the electrodes (1013, 1015, 1018, 1020, 1022) are paired in this manner and energized with an appropriate voltage pulse waveform of appropriate amplitude, the electrodes (1013, 1015, 1018, 1020, 1022) can generate an ablation zone having a depth that is nearly independent of the orientation of the electrodes (1013, 1015, 1018, 1020, 1022) relative to the tissue, as will be further described with reference to Figures 5-8.

[0045] 5-8 illustrate different ablation zones that can be created in tissue using the systems, devices, and methods as described herein. FIG. 5 illustrates a simulation of an ablation zone that can be created in a tissue wall (560) by an ablation device (500). The ablation device (500) can be structurally and / or functionally similar to other ablation devices described herein, including, for example, ablation devices (110, 400, 900, 1000). For example, the ablation device (500) can include a body (511), a distal tip electrode (519), and proximal electrodes (521, 523).

[0046] As illustrated in FIG. 5, the distal tip electrode (519) may be positioned approximately perpendicular to a tissue wall 560 (e.g., a cardiac tissue wall). In other words, a distal portion of the body (511) of the ablation device (500), including at least the distal tip electrode (519), may be positioned to extend in a direction approximately perpendicular to a surface of the tissue wall (560). The distal portion of the body (511) may be positioned generally within a blood pool (550) adjacent the tissue wall (560), such as a blood pool within a cardiac cavity. The tissue wall (560) may have a thickness T in the range of about 1 mm to about 8 mm, including all values ​​and subranges therebetween.

[0047] According to the methods described herein, the pulse waveform can be generated and delivered to the ablation device (500), for example, using a signal generator (e.g., signal generator (122)). To form the simulated ablation zone (570) shown in FIG. 5, the tip electrode (519) is configured to have a first polarity and the proximal electrodes (521, 523) are configured to have a second polarity opposite the first polarity. For example, the signal generator can be configured to deliver output signals associated with the pulse waveform having opposite polarities to the tip electrode (519) and the proximal electrodes (521, 523), respectively. Thus, the tip electrode (519) can be polarized with one electrical polarity and the proximal electrodes (521, 523) can be polarized with the opposite electrical polarity. The tip electrode (519) and the proximal electrodes (521, 523) can be polarized with a pulse waveform having a voltage amplitude of at least about 0.5 kV (eg, 1 kV) to generate a pulsed electric field having an ablation zone (570).

[0048] 6 shows a simulation of an ablation zone created in a tissue wall (660) by an ablation device (600) oriented at an angle to the tissue wall (660). The ablation device (600) may be structurally and / or functionally similar to other ablation devices described herein, including, for example, ablation devices (110, 400, 500). For example, the ablation device (600) may include a body (611), a distal tip electrode (619), and proximal electrodes (621, 623).

[0049] As illustrated in FIG. 6, the distal tip electrode (619) may be placed at an angle (e.g., from about 0 to about 90 degrees, including all subranges and values ​​therebetween) relative to the tissue wall (660). The distal portion of the ablation device (600) may be positioned within the blood pool (650). The tissue wall (660) may have a thickness T ranging from about 1 mm to about 8 mm. Using a pulse waveform having the same voltage amplitude (e.g., 1 kV) and the same electrode subset configuration (i.e., the tip electrode (619) has one electrical polarity and the proximal electrodes (621, 623) have the opposite electrical polarity), the electrodes (619, 621, 623) may generate a pulsed electric field having an ablation zone (670). When comparing the ablation zone (670) created by the obliquely oriented ablation device (600) with the ablation zone (570) created by the orthogonally oriented ablation device (500), the depth of the ablated tissue region is similar. Specifically, the ablation zone (670) created by the obliquely oriented ablation device (600) has a depth approximately equal to the depth of the ablation zone (570) created by the orthogonally oriented ablation device (500). Thus, the ablation devices described herein (e.g., ablation devices (500, 600)) can create ablation zones independent of orientation.

[0050] The devices and systems described herein can generate controllable ablation zones, independent of orientation, with pulse waveforms having various voltage amplitudes, such as amplitudes ranging from about 400V, about 1,000V, about 5,000V, about 10,000V, about 15,000V, including all values ​​and subranges therebetween. As an example, Figures 7 and 8 show simulated ablation zones (770, 870) generated using pulse waveforms having higher voltages than those of Figures 5 and 6. For example, the ablation devices (700, 800) shown in Figures 7 and 8 can be energized with a pulse waveform having a voltage amplitude of 2 kV.

[0051] 7 shows a simulated ablation zone (770) created in a tissue wall (760) by an ablation device (700) placed approximately perpendicular to the tissue wall (760). The ablation device (700) may be structurally and / or functionally similar to other ablation devices described herein, including, for example, ablation devices (110, 400, 500, 600). For example, the ablation device (700) may include a body (711), a distal tip electrode (719), and proximal electrodes (721, 723).

[0052] As illustrated in FIG. 7, the distal tip electrode (719) may be placed approximately perpendicular (e.g., approximately 90 degrees) to the tissue wall (760). The distal portion of the ablation device (700) may be positioned within the blood pool (750). The tissue wall (760) may have a thickness T ranging from approximately 1 mm to approximately 8 mm. Using a pulse waveform having individual pulses with an amplitude of 2 kV, and with opposite polarity applied to the tip electrode (719) and the proximal electrodes (721, 723), the electrodes (719, 721, 723) may generate a pulsed electric field having an ablation zone (770). As illustrated, the ablation zone (770) may have a depth greater than the depth of the ablation zones (570, 670) due to the higher voltage of the pulse waveform.

[0053] 8 illustrates a simulated ablation zone (870) created in a tissue wall (860) by an ablation device (800) placed at an angle relative to the tissue wall (860). The ablation device (800) may be structurally and / or functionally similar to other ablation devices described herein, including, for example, ablation devices (110, 400, 500, 600, 700). For example, the ablation device (800) may include a body (811), a distal tip electrode (819), and proximal electrodes (821, 823).

[0054] As shown in FIG. 8, the distal tip electrode (819) may be placed at an angle (e.g., from about 0 to about 90 degrees, including all subranges and values ​​therebetween) relative to the tissue wall (860). The distal portion of the ablation device (800) may be positioned within the blood pool (850). The tissue wall (860) may have a thickness T ranging from about 1 mm to about 8 mm. Using a pulse waveform having individual pulses with an amplitude of 2 kV, and with opposite polarity provided to the tip electrode (819) and the proximal electrodes (821, 823), the electrodes (819, 821, 823) may generate a pulsed electric field having an ablation zone (870). As shown, the ablation zone (870) may have a depth greater than the depth of the ablation zones (570, 670) due to the higher voltage of the pulse waveform. Ablation zone (870) has a similar depth (e.g., approximately the same depth) as compared to ablation zone (770) in Figure 7. Thus, Figures 7 and 8 provide further examples of ablation devices described herein that are capable of producing controllable ablation zones independent of the orientation of the ablation device relative to the tissue wall.

[0055] It should be understood that the tip of the ablation catheter of the present invention may be placed on the tissue surface in any orientation that is convenient in clinical use, whether perpendicular, oblique, or tangential to the local tissue surface. The specific examples provided herein are provided for illustrative purposes only.

[0056] 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 / or "approximately" may mean within ±10% of the recited numerical value. For example, in some cases, [about 100 units] may mean within ±10% of 100 (e.g., 90 to 110). The terms "about" and / or "approximately" may be used interchangeably.

[0057] As used herein, the terms "set" and / or "subset" of components (eg, electrodes) generally refer to a single one of those components or a plurality of those components.

[0058] Some embodiments described herein relate to computer storage products that include 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 inherently include ephemeral propagating signals (e.g., propagating electromagnetic waves that carry information in a transmission medium such as space or a cable). The medium and computer code (which may also be referred to as code or algorithms) may be designed and constructed for a specific purpose. Examples of non-transitory computer readable media include, but are not limited to, magnetic storage media such as hard disks, magnetic disks and magnetic tapes; optical storage media such as compact discs / digital video discs (CD / DVDs), compact disc-read only memories (CD-ROMs) and holographic devices; magneto-optical storage media such as optical discs; carrier wave signal processing modules; and hardware devices specially configured to store and execute program code, such as application specific integrated circuits (ASICs), programmable logic devices (PLDs), read only memory (ROM) and random access memory (RAM) devices. Other embodiments described herein relate to computer program products that may include, for example, instructions and / or computer code disclosed herein.

[0059] The systems, devices and / or methods described herein may be implemented 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 a variety of 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, e.g., machine instructions generated by a compiler, code used to generate web services, and files containing higher level instructions that a computer executes using an interpreter. Further examples of computer code include, but are not limited to, control signals, encrypted code, and compressed code.

[0060] (Additional Note) As a preferred embodiment, the technical ideas that can be understood from the above embodiment will be described below. [Item 1] a linear shaft including a distal portion positionable near a tissue wall, the linear shaft configured to be deflectable to position the distal portion near the tissue wall; a plurality of electrodes disposed on the distal portion configured to generate a pulsed electric field capable of producing an ablation zone within the tissue wall having a depth independent of an orientation of the distal portion relative to the tissue wall; a set of distal electrodes including a distal tip electrode disposed at a distal end of the linear shaft and an adjacent distal electrode spaced proximally from the distal tip electrode by a distance; a set of proximal electrodes disposed proximally of the set of distal electrodes, a first length of the linear shaft separating at least one adjacent pair of proximal electrodes of the set of proximal electrodes, a second length of the linear shaft separating a most distal proximal electrode of the set of proximal electrodes from a most proximal distal electrode of the set of proximal electrodes, the first length of the linear shaft being less than the second length of the linear shaft, and the first length being greater than the fixed distance; A plurality of electrodes including: a plurality of leads coupled to the plurality of electrodes, each lead from the plurality of leads configured to deliver a voltage output having an amplitude of at least 700V to the plurality of electrodes (1) without breakdown of its corresponding insulation, and (2) such that the set of distal electrodes is operated with a first polarity and the set of proximal electrodes is operated with a second polarity opposite the first polarity to collectively generate the pulsed electric field; An apparatus comprising: [Item 2] 2. The apparatus of claim 1, wherein the set of proximal electrodes includes two proximal electrodes. [Item 3] 3. The device of claim 2, wherein the set of distal electrodes further includes one or more distal electrodes disposed proximal to the distal tip electrode, and a third length of the linear shaft separates the distal tip electrode from an adjacent distal electrode of the one or more distal electrodes. [Item 4] 4. The apparatus of claim 3, wherein the first length of the linear shaft and the third length of the linear shaft are less than the second length of the linear shaft. [Item 5] 5. The device of claim 4, wherein the two proximal electrodes are wired together using a first lead from the multiple leads, and the distal tip electrode and the one or more distal electrodes are wired together using a second lead from the multiple leads. [Item 6] 4. The device of claim 3, wherein the two proximal electrodes are wired together using a first lead from the multiple leads, the distal tip electrode is wired independently using a second lead from the multiple leads, and the one or more distal electrodes are wired independently or together using a third lead from the multiple leads. [Item 7] Item 2. The apparatus of item 1, wherein the linear shaft has a diameter of 1 mm to 5 mm. [Item 8] Each proximal electrode from the set of proximal electrodes has a length between 1 mm and 6 mm; and 8. The apparatus of claim 7, wherein each distal electrode from the set of distal electrodes has a length of between 1 mm and 8 mm. [Item 9] 8. The apparatus of claim 7, wherein a ratio of the second length of the linear shaft to the first length of the linear shaft is 1 to 20. [Item 10] a pull wire having a proximal end and a distal end; the distal end of the pull wire is coupled to the linear shaft near the set of proximal electrodes and proximal to the second length of the linear shaft; the proximal end of the pull wire is coupled to an actuation mechanism; 2. The device of claim 1, wherein the pull wire is configured to be actuated via the actuation mechanism to deflect the linear shaft such that deflection of the linear shaft deflects the second length of the linear shaft. [Item 11] a pull wire having a proximal end and a distal end; the distal end of the pull wire is coupled to the distal portion of the linear shaft; the proximal end of the pull wire is coupled to an actuation mechanism; 2. The device of claim 1, wherein the pull wire is configured to be actuated via the actuation mechanism to deflect the linear shaft. [Item 12] further comprising a sensor disposed in the distal portion; 2. The device of claim 1, wherein the sensor is configured to receive a set of signals to determine a position of the distal portion in response to at least one of an electric field or a magnetic field generated by a field generator associated with a tracking device. [Item 13] Item 13. The apparatus of item 12, wherein a subset of the set of distal electrodes is configured to measure electrocardiogram (ECG) data. The specific examples and descriptions herein are exemplary in nature and embodiments may be developed by one of ordinary skill in the art based on the material taught herein without departing from the scope of the invention, which is limited only by the appended claims.

Claims

1. a linear shaft including a distal portion positionable near a tissue wall, the linear shaft configured to be deflectable to position the distal portion near the tissue wall; A plurality of electrodes disposed on the distal portion, a distal electrode set including two or more distal electrodes; a set of proximal electrodes disposed proximally of the set of distal electrodes, a first length of the linear shaft separating at least one adjacent pair of proximal electrodes of the set of proximal electrodes, and a second length of the linear shaft separating a distal-most proximal electrode of the set of proximal electrodes from a proximal-most distal electrode of the set of proximal electrodes; A plurality of electrodes including: a plurality of leads coupled to the plurality of electrodes, each lead having insulation configured to withstand a potential difference of at least about 700 V without dielectric breakdown, and configured such that at least two of the distal electrodes are wired together; an ablation device comprising: a signal generator operably coupled to the ablation device, the signal generator configured to activate at least one distal electrode from the set of distal electrodes having a first polarity and the set of proximal electrodes having a second polarity opposite to the first polarity such that the plurality of electrodes generates pulsed electric field energy capable of producing an ablation zone within the tissue wall having a depth independent of an orientation of the distal portion relative to the tissue wall; A system comprising:

2. The system of claim 1 , wherein the set of proximal electrodes includes two proximal electrodes.

3. The system of claim 2 , wherein the set of distal electrodes includes at least a distal tip electrode disposed at a tip of the linear shaft.

4. The set of distal electrodes comprises: a distal tip electrode disposed at a tip of the linear shaft; one or more additional distal electrodes disposed proximal to the distal tip electrode, a third length of the linear shaft separating the distal tip electrode from adjacent distal electrodes of the one or more distal electrodes; The system of claim 2 , comprising:

5. 5. The system of claim 4, wherein the two proximal electrodes are wired together using a first lead from the multiple leads, and the distal tip electrode and the one or more additional distal electrodes are wired together using a second lead from the multiple leads.

6. 5. The system of claim 4, wherein the two proximal electrodes are wired together using a first lead from the multiple leads, the distal tip electrode is independently wired using a second lead from the multiple leads, and the one or more additional distal electrodes are wired together using a third lead from the multiple leads.

7. The system of claim 1 , wherein the ablation device further comprises a pull wire configured to be actuated to deflect the linear shaft, the pull wire coupled to a location along the distal portion of the linear shaft.

8. The system of claim 1 , wherein each of the first length of the linear shaft and the second length of the linear shaft is between 0.5 mm and 12 mm.

9. The system of claim 8 , wherein a ratio of the second length of the linear shaft to the first length of the linear shaft is between 1 and 20.

10. a tracking device configured to track a position of the distal portion of the linear shaft during positioning, the tracking device including a field generator configured to generate at least one of an electric field or a magnetic field; 10. The system of claim 1, wherein the ablation device further comprises a sensor disposed on the distal portion configured to receive a set of signals in response to a generated field to determine the position of the distal portion of the linear shaft.

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