Systems, devices, and methods for focal ablation

Abstract

Systems, devices, and methods for focal ablation are disclosed. A device may include a linear shaft including a distal portion positionable proximate a tissue wall. The linear shaft may be configured to deflect to position the distal portion proximate a tissue wall. The device may include a plurality of electrodes disposed on a distal portion of the linear shaft, where the plurality of electrodes are configured to generate a pulsed electric field that creates an ablation zone in the tissue wall having a depth independent of an orientation of the distal portion relative to the tissue wall.

Description

[0001] This application is a divisional application of application number 2020800589908, application date June 16, 2020, and invention name “Systems, devices and methods for focal ablation”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application is a continuation of and claims the benefit of U.S. Provisional Application No. 62 / 863,588, filed on June 19, 2019, entitled “SYSTEMS, DEVICES, AND METHODS FOR FOCAL ABLATION”, filed on March 24, 2020. This application also claims the benefit of U.S. Provisional Application No. 62 / 863,588. The entire disclosure of each of the foregoing applications is incorporated herein by reference in its entirety. Background Art

[0004] Over the past two decades, the generation of pulsed electric fields for tissue therapy has moved from the laboratory to clinical applications, and over the past four decades or more, the effects of short pulses of high voltage and large electric fields on tissues have been studied. Applying a brief high DC voltage to the tissue can generate a local high electric field, typically in the range of hundreds of volts per centimeter, that destroys the cell membrane by generating holes in the cell membrane. Although the precise mechanism of this electrically driven pore generation or electroporation continues to be studied, it is believed that the application of a relatively brief and large electric field generates instability in the lipid bilayer in the cell membrane, resulting in a distribution of local gaps or holes in the cell membrane. If the electric field applied at the membrane is greater than a threshold value so that the pores do not close and remain open, thereby allowing biomolecular substances to exchange across the membrane, resulting in necrosis and / or apoptosis (cell death), then this electroporation may be irreversible. Subsequently, the surrounding tissue may heal naturally.

[0005] Although pulsed DC voltage can drive electroporation under appropriate circumstances, there remains an unmet need for thin, flexible, non-invasive devices that effectively deliver high DC voltage electroporation ablation therapy selectively to endocardial tissue in regions of interest while minimizing damage to healthy tissue. Summary of the invention

[0006] Described herein are systems, devices, and methods for ablating tissue by irreversible electroporation. Typically, a device (e.g., a catheter) for applying pulsed electric field ablation to soft tissue (e.g., cardiac tissue) can include a linear flexible body with multiple distally placed electrodes. In some embodiments, the device can be used to form a focal ablation lesion.

[0007] 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 being 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 distal electrode set; and a proximal electrode set disposed proximal to the distal electrode set, each proximal electrode from the proximal electrode set being spaced apart from an adjacent proximal electrode from the proximal electrode set by a first length of the linear axis, a distal-most proximal electrode from the proximal electrode set being spaced apart from a proximal-most distal electrode from the distal electrode set by a second length of the linear axis; and a plurality of leads coupled to the plurality of electrodes, each lead having an insulation portion 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 is configured to activate at least one distal electrode from the distal electrode set with a first polarity and to activate the proximal electrode set with a second polarity opposite to the first polarity, so that the multiple electrodes generate pulsed electric field energy that produces an ablation zone in the tissue wall having a depth that is independent of the orientation of the distal portion relative to the tissue wall.

[0008] In some embodiments, a device includes: a linear shaft including a distal portion positionable near a tissue wall, the linear shaft being 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 being configured to generate a pulsed electric field that produces an ablation zone in the tissue wall having a depth that is independent of the orientation of the distal portion relative to the tissue wall, the plurality of electrodes including: a distal electrode set including a distal tip electrode disposed at a tip of the linear shaft; and a proximal electrode set disposed proximal to the distal electrode set, each proximal electrode from the proximal electrode set being adjacent to an electrode from the proximal electrode set. Adjacent side electrodes in the side electrode set are spaced apart by a first length of the linear axis, a farthest proximal electrode from the proximal electrode set is spaced apart by a second length of the linear axis from a nearest distal electrode from the distal electrode set, the first length of the linear axis being less than the second length of the linear axis; and a plurality of leads coupled to the plurality of electrodes, each lead from the plurality of leads being 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 insulating portion, and (2) such that the distal electrode set is activated with a first polarity and the proximal electrode set is activated with a second polarity opposite to the first polarity to collectively generate a pulsed electric field.

[0009] In some embodiments, a method includes: positioning a linear axis of an ablation device in a cardiac chamber of a subject's heart so that a distal portion of the linear axis is near a tissue wall, the ablation device including a plurality of electrodes disposed on the distal portion, the plurality of electrodes including a distal electrode set and a proximal electrode set, each proximal electrode from the proximal electrode set being spaced apart from an adjacent proximal electrode from the proximal electrode set by a first length of the linear axis, and a distal-most proximal electrode from the proximal electrode set being spaced apart from a proximal-most distal electrode from the distal electrode set by a second length of the linear axis; and using a signal generator to generate a pulse waveform having a voltage amplitude of at least about 700 V; delivering a pulse waveform having a first polarity to the distal electrode set, and delivering a pulse waveform having a second polarity opposite to the first polarity to the proximal electrode set, so that the plurality of electrodes together generate a pulsed electric field that produces an ablation zone in the tissue wall having a depth that is independent of the orientation of the distal portion relative to the tissue wall. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a block diagram of an electroporation system according to an embodiment.

[0011] Figure 2 A method for tissue ablation according to an embodiment is shown.

[0012] Figure 3 A method for tissue ablation according to an embodiment is shown.

[0013] Figure 4 A schematic diagram of the distal end of an ablation catheter according to an embodiment is shown.

[0014] Figure 5 An electric field generated by electrodes of an ablation catheter positioned proximate tissue is shown according to an embodiment.

[0015] Figure 6 An electric field generated by electrodes of an ablation catheter positioned adjacent tissue is shown according to an embodiment.

[0016] Figure 7 An electric field generated by electrodes of an ablation catheter positioned proximate tissue is shown according to an embodiment.

[0017] Figure 8 An electric field generated by electrodes of an ablation catheter positioned adjacent tissue is shown according to an embodiment.

[0018] Fig. 9 A schematic diagram of the distal end of an ablation catheter according to an embodiment is shown.

[0019] Fig.10 A schematic diagram of the distal end of an ablation catheter according to an embodiment is shown. DETAILED DESCRIPTION

[0020] Systems, devices and methods for applying pulsed electric fields to ablated tissues by irreversible electroporation are described herein. In some embodiments, the systems, devices and methods described herein can be configured to provide focal ablation. Such systems, devices and methods can generate a controllable ablation zone in tissue in a manner that is independent of orientation (i.e., generally independent of the orientation of the ablation device (e.g., catheter) relative to a tissue surface or wall).

[0021] The term "electroporation" as used herein refers to the application of an electric field to the 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 the cell membrane to temporarily change the permeability of the cell membrane to the extracellular environment. For example, cells undergoing reversible electroporation can observe temporary and / or intermittent formation of one or more holes in their cell membranes, which are closed when the electric field is removed. The term "irreversible electroporation" as used herein refers to the application of an electric field to the cell membrane to permanently change the permeability of the cell membrane to the extracellular environment. For example, cells undergoing irreversible electroporation can observe the formation of one or more holes in their cell membranes, which still exist after the electric field is removed.

[0022] In general, the systems and devices described herein include one or more ablation devices (eg, catheters) configured to ablate tissue, such as tissue in a chamber (eg, atria, ventricles) of the heart. Figure 1An ablation system (100) is shown. The system (100) may include an apparatus (120) including a signal generator (122), a processor (124), a memory (126), and optionally a cardiac stimulator (128). The apparatus (120) may be coupled to an ablation device (110) and optionally to a pacing device (130).

[0023] The signal generator (122) can be configured to generate a voltage pulse waveform for irreversible electroporation of tissue (e.g., an endocardial wall). For example, the signal generator (122) can be a voltage pulse waveform generator and deliver a pulse waveform to the ablation device (110). The processor (124) can combine 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 to be generated by the signal generator (122). The memory (126) can also store instructions to 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) can be configured to store pulse waveforms and / or cardiac pacing data for pulse waveform generation and / or cardiac pacing, respectively.

[0024] In some embodiments, the ablation device (110) may include a catheter configured to receive and / or deliver a pulse waveform, which will be described in more detail below. For example, the ablation device (110) can be introduced into the endocardial space of a chamber of the heart and positioned so that one or more electrodes (112) of the ablation device (110) are proximate to target tissue (e.g., the endocardial wall). The ablation device (110) can then deliver the pulse waveform to ablate the tissue. In some embodiments, the one or more electrodes (112) of the ablation device (110) can include one or more independently addressable electrodes, as described below with reference to Figures 4 to 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 its corresponding insulation. In some embodiments, the insulation on each electrical lead may maintain a potential difference of between about 200V and about 3000V across its thickness without dielectric breakdown.

[0025] In some embodiments, the apparatus (120) may be coupled 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 for cardiac stimulation (e.g., generated by an optional cardiac stimulator (128) of the apparatus (120)). 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 indication of a 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 synchronized with the indication of the pacing signal (e.g., within a refractory period window associated with an atrial or ventricular pacing signal). For example, in some embodiments, the refractory period window may begin substantially immediately after the ventricular pacing signal (or after a very small delay) and continue thereafter for a duration of approximately 250 ms or less. In such embodiments, the entire pulse waveform may be delivered within this duration.

[0026] In some embodiments, the system (100) may include a tracking system or device (140). The tracking system (140) may be operably coupled to the device (120) 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) and, in particular, a distal portion of the ablation device (110) as the ablation device (110) is navigated through an anatomical structure. The tracking system (140) may include a field generator (142) comprising 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 that may generate and maintain a potential difference between them over a range of frequencies. 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 can be received as signals (e.g., voltage, current, or both) by a set of sensors (114) disposed near and / or incorporated into the ablation device (110). In an embodiment, the (multiple) sensors (114) can be electromagnetic sensors incorporated into a distal portion of the ablation device (110) (e.g., a distal portion of a catheter). Using the tracked position information, a visual representation of the ablation device (100) can be displayed in an electroanatomical map or an anatomical map, for example to provide a spatial scene for visualizing the position of the catheter. Such a visual representation can be generated by, for example, a processor (124) or another processing device coupled to and / or integrated into the device (120) and / or tracking system (140). Suitable examples of tracking systems for use with ablation devices are described in U.S. patent application Ser. No. 16 / 785,392, filed on February 7, 2020, and entitled “METHOD, SYSTEM, AND APPARATUSES FOR TRACKING ABLATION DEVICES AND GENERATING LESION LINES,” the contents of which are incorporated herein by reference.

[0027] 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) in an anatomical structure. The actuation mechanism may be controlled by an operator based on the position of the distal portion of the ablation device (110). For example, based on the tracked position of the ablation device (110) tracked by the tracking system (140), the operator may control the angle or orientation of the distal portion of the ablation device (110) to manipulate the ablation device (110) to a specific position.

[0028] The processor (124) can be any suitable processing device configured to run and / or execute a set of instructions or codes. The processor can 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 can 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 associated therewith (not shown). The underlying device technology can be provided in various component types, for example, metal-oxide semiconductor field-effect transistor (MOSFET) technology like complementary metal-oxide semiconductor (CMOS), bipolar technology like emitter-coupled logic (ECL), polymer technology (e.g., silicon conjugated polymer and metal conjugated polymer-metal structure), mixed analog and digital, etc.

[0029] 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), flash memory, etc. The memory (126) may store instructions to 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.

[0030] The system (100) can communicate with other devices (not shown) via, for example, one or more networks, each of which can be any type of network. A wireless network can refer to any type of digital network that is not connected by any type of cable. However, a wireless network can be connected to a wired network to connect to the Internet, other operator voice and data networks, business networks, and personal networks. A wired network is typically carried by copper twisted pairs, 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). Hereinafter, a network refers to any combination of wireless, wired, public, and private data networks that are typically interconnected by the Internet to provide a unified networking and information access solution.

[0031] The ablation systems described herein (eg Figure 1 The system (100) depicted can be configured as follows: Figure 2 and Figure 3 The depicted method uses. In some embodiments, the ablation system can be used to ablate tissue in a cardiac chamber (e.g., a left atrial chamber). Generally, the methods described herein include introducing and placing a device adjacent to and / or in contact with an endocardial wall. A pulse waveform can be delivered by one or more electrodes of the device to ablate tissue. In some embodiments, a cardiac pacing signal can synchronize the delivered pulse waveform with the cardiac cycle. Tissue ablation performed in this manner can be delivered synchronously with the paced heartbeat and with less energy delivery to reduce damage to healthy tissue. It should be understood that any of the ablation devices described herein can be used to ablate tissue appropriately using the methods discussed below.

[0032] In some embodiments, the ablation devices described herein can be used for focal ablation of cardiac features / structures identified as causing arrhythmias. For example, focal ablation may produce a point lesion that neutralizes the rotor while protecting surrounding tissue. Further details of the ablation zones generated using the systems, devices, and methods disclosed herein are provided below. Figures 5 to 8 Give a description.

[0033] Figure 2An example method (200) for ablating tissue is depicted. The method (200) includes introducing a device (e.g., ablation device (110)) into an endocardial space of a chamber of the heart at (202). 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 comprising a plurality of distally positioned electrodes, and such electrodes may be positioned near or in contact with a tissue surface, such as an endocardial wall in a cardiac chamber (such as the left atrium or the right atrium). The method (200) may include manually or automatically configuring one or more electrodes of the ablation device as anode(s) and / or cathode(s), at (206). In some embodiments, the ablation device may include one or more distal electrodes and one or more proximal electrodes, and at least one distal electrode and at least one proximal electrode may be configured as an anode-cathode set. For example, as described below with reference to Figures 4 to 10 As further described, the ablation device can include a distal tip electrode and two proximal electrodes, and the distal tip electrode can be paired with the two proximal electrodes to form an anode-cathode set. In alternative embodiments, the ablation device can have less than or more than three electrodes, such as two, four, five, or six electrodes, wherein the electrodes include distal and proximal electrode subsets. In some embodiments, the voltage pulse waveform can 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 can be selected as an anode, and the proximal electrode of the ablation device can be selected as a cathode, wherein the voltage pulse waveform is applied between the anode and the cathode.

[0034] Optionally, the voltage level (e.g., the amplitude of one or more voltage pulses) of the pulse waveform or a portion of the pulse waveform can be set at (207). For example, the voltage level can be increased to produce a deeper ablation zone, which is useful when the tissue is thicker. As a set of non-limiting examples, the amplitude of a single pulse of the example pulse waveform can be in the range of about 400V, about 1000V, about 5000V, about 10000V, about 15000V, including all values ​​and sub-ranges therebetween.

[0035] At (208), a pulse waveform may be generated by a signal generator (eg, signal generator (122)). In some embodiments, the pulse waveform may be a voltage pulse waveform including a plurality of levels of a hierarchical structure, while in alternative embodiments, other waveforms may be used. Examples of suitable pulse waveforms including multiple levels of a hierarchical structure are disclosed in international application serial number PCT / US2016 / 057664, filed on October 19, 2016, entitled “SYSTEMS, APPARATUSES AND METHODS FOR DELIVERY OF ABLATIVE ENERGY TO TISSUE” and international application serial number PCT / US2019 / 031135, filed on May 7, 2019, entitled “SYSTEMS, APPARATUSES AND METHODS FOR DELIVERY OF ABLATIVE ENERGY TO TISSUE”, the contents of each of which are incorporated herein by reference in their entirety. As disclosed herein, various hierarchical structure waveforms can be generated using a signal generator (e.g., signal generator (122)).

[0036] At (210), the generated pulse waveform can be delivered to (multiple) anode-cathode electrode sets such that the (multiple) electrode sets generate an electric field that ablates tissue. For example, a distal tip electrode of an ablation catheter can be polarized with a first electrical polarity, while a proximal electrode of the ablation catheter can be polarized with a second electrical polarity opposite to the first electrical polarity, such that the distal tip electrode and the proximal electrode generate an electric field capable of forming a lesion. As another example, in an embodiment having four electrodes, the distal electrode pair can have one electrical polarity, while the proximal electrode pair can have an opposite electrical polarity during ablation delivery, while the multiple electrodes thus jointly generate an electric field for ablation. Reference Figures 4 to 10 Additional details of these embodiments are described. The spatial form of the injury can have a controlled depth or volume, for example by applying a suitable waveform, as described herein, and having a suitable voltage level, electrode geometry, and / or electrode pairing. In some embodiments, one or more voltage pulse waveforms can be applied over a series of heartbeats, for example during a refractory time window, as further described below.

[0037] In some embodiments, the voltage pulse waveforms described herein may be applied during the refractory period of the cardiac cycle in order to avoid disruption of the heart's sinus rhythm. Figure 3Another example method (300) of ablating tissue is depicted. The method (300) can be similar to the method (200) described above, but includes steps for applying a pulse waveform synchronously with one or more pacing signals. The method (300) includes introducing a device (e.g., an ablation device (110)) into an endocardial space of a chamber of the heart at (302). The device can be advanced to be positioned adjacent to a tissue wall of the heart, such as at an endocardial surface in the left atrium or the right atrium. For example, the ablation device can be a linear flexible device that includes a plurality of distally placed electrodes, and such electrodes can be positioned adjacent to or in contact with the endocardial wall. In some embodiments, at (312), a pacing signal can be generated for cardiac stimulation of the heart. Then, at (314), the pacing signal can be applied to the heart. For example, the heart can be electrically paced using a cardiac stimulator (e.g., cardiac stimulator (128)) to ensure pacing capture, thereby establishing periodicity and predictability of the cardiac cycle. One or more of atrial and ventricular pacing can be applied. At (316), an indication of a pacing signal may be transmitted to a signal generator. A time window within the refractory period of the cardiac cycle may then be defined within which 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 located between atrial and ventricular refractory time windows.

[0038] At (308), a pulse waveform may be generated synchronously with the pacing signal. For example, a voltage pulse waveform may be applied in a common refractory period time window. In some embodiments, the pulse waveform may be generated with a time offset relative to an indication of the pacing signal. For example, the start of the refractory period time window may be offset from the pacing signal by a certain time offset. (Multiple) voltage pulse waveforms may be applied over a series of heartbeats over corresponding common refractory period time windows. At (310), the generated pulse waveform may be delivered to an ablation device so that the ablation device generates a pulsed electric field for ablating tissue.

[0039] The methods described herein may be implemented using a system including one or more multi-electrode ablation devices. Figure 4 is a side view of an ablation device (400). The ablation device (400) may include a device that is structurally and / or functionally similar to the ablation device described above. Figure 1A component of the ablation device (110) described herein. The ablation device (400) may be a flexible linear catheter having a plurality of distally positioned electrodes. The ablation device (400) may include a shaft or body (431) and a plurality of electrodes (419, 421, 423), the plurality of electrodes including a distal tip electrode (419) and a proximal electrode (421, 423). The plurality of electrodes (419, 421, 423) may be located on a distal portion of the body (431), with the proximal electrode (421, 423) located proximal to the tip electrode (419), and each electrode (419, 421, 423) being separated from an adjacent electrode by a shaft portion (433, 435).

[0040] The electrodes (419, 421, 423) can be positioned so that they are adjacent to and / or in contact with tissue (e.g., endocardial tissue). However, although the electrodes (419, 421, 423) can be configured to touch the endocardial tissue, it should be understood that the electrodes (419, 421, 423) need not touch the endocardial tissue to form an ablation zone, as described herein.

[0041] One or more of the electrodes (419, 421, 423) may be independently addressable electrodes. In some embodiments, subsets of the electrodes (419, 421, 423) may be wired in conjunction. For example, the proximal electrodes (421, 423) may be wired in conjunction, while the distal tip electrode (419) may be independently addressable or wired separately 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 its corresponding insulating portion. In other embodiments, the insulating portion on each of the electrical leads may maintain a potential difference of between about 200V and about 2000V (including all subranges and values ​​therebetween) over its thickness without dielectric breakdown. The body (431) may include an insulated electrical lead for each electrode (419, 421, 423), such as in an internally defined lumen.

[0042] In some embodiments, the shaft portion (433, 435) separating the electrodes (419, 421, 423) can be flexible so that the ablation device (400) can be deflected, for example, positioned adjacent to a target tissue (e.g., soft tissue within the heart). In other embodiments, one or both of the intermediate shaft portions (433, 435) can be rigid or semi-rigid. A pull wire (440) can be disposed within the ablation device (400) for deflecting the ablation device (400). The pull wire (440) can be attached to a rigid portion of the body (431), such as where the electrodes (419, 421, 423) are disposed, and pulled to deflect a portion of the body (431) proximal to the attachment location. In some embodiments, the shaft portion (433, 435) is configured to deflect with a more proximal portion of the body (440). The pull wire (440) can be attached to a handle (not shown) at the proximal end of the ablation device (400), which can be used to control the deflection of the body (431). The handle can include a mechanism for deflecting or manipulating the distal portion of the ablation device (400), such as by tightening the pull wire (440).

[0043] According to the methods described herein, the ablation device (400) can be used to generate an ablation zone in tissue by applying a high voltage waveform for pulsed electric field ablation, thereby generating an ablated tissue zone via irreversible electroporation. The ablation device (400) can be used for clinical applications, including for cardiac ablation, for example, for treating arrhythmias. In some embodiments, the ablation device (400) can generate a focal or localized ablation zone having a diameter of about 5 mm to about 15 mm and a depth of about 1 mm to about 6 mm.

[0044] In some embodiments, one or more pulse waveforms can be applied between electrodes (419, 421, 423) configured in an anode set and a cathode set. For example, a distal tip electrode (419) can be electrically paired with a proximal electrode (421, 423). A signal generator (e.g., signal generator (122)) can be used to deliver a pulse waveform 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 jointly polarized with a second electrical polarity that is opposite to the first electrical polarity. In some embodiments, as described above, the pulse waveform can be a hierarchical structure waveform, while in other embodiments, other waveform structures can be used. When the electrodes (419, 421, 423) are paired in this way and excited with a voltage pulse waveform of appropriate amplitude, the electrodes (419, 421, 423) can generate an ablation zone having a depth that is generally independent of the orientation of the electrodes (419, 421, 423) relative to the tissue, as described below with reference to Figures 5 to 8 As further described.

[0045] In some embodiments, the body (431) can have a diameter between about 1 mm and about 5 mm, including all subranges and values ​​therebetween. For example, in some embodiments, the body 431 can have a diameter between about 4 French (1.33 mm) and about 15 French (5 mm). In some embodiments, the distal tip electrode (419) has a length L1 in the range of about 1 mm to about 8 mm. In some embodiments, the proximal electrodes (421, 423) can each have a length L2 in the range of about 1 mm to about 6 mm. In some embodiments, the distal tip electrode (419) can have a length L1 greater than the length L2 of the proximal electrodes (421, 423). In some embodiments, the proximal electrodes (421, 423) can have different lengths. In some embodiments, the shaft portions (433, 435) separating adjacent electrodes (419, 421, 423) can each have a length in the range of about 1 mm to about 10 mm. In some embodiments, the distance D1 separating the tip electrode (419) from the first proximal electrode (423) can be greater than the distance D2 separating the first proximal electrode (423) from the second proximal electrode (421). Alternatively, the distance D1 and the distance D2 separating the adjacent electrodes ((419, 421, 423)) can be equal to each other, or the distance D2 can be greater than the distance D1.

[0046] Although ablation device (400) is depicted as having a single distal tip electrode (419) and two proximal electrodes (421, 423), it will be appreciated that ablation device (400) may include an additional number of distal electrode(s) and / or proximal electrode(s). For example, in an alternative arrangement, ablation device (400) may include more than two 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.

[0047] Fig. 9 The distal portion of the ablation device (900) is schematically depicted. The ablation device (900) may be and / or include other ablation devices that are structurally and / or functionally similar to those described herein (including, for example, as described above with reference to Figure 1The ablation device (900) can be a flexible linear catheter having a distal portion (911) comprising a distal electrode set (918, 920) and a proximal electrode set (913, 915). The distal electrode set (918, 920) can be separated from the proximal electrode set (913, 915) by a shaft portion (924). In some embodiments, the shaft portion 924 can be flexible, while in alternative embodiments, the shaft portion 924 can be rigid or substantially rigid. A pull wire (940) can be disposed within the ablation device (900) for deflecting the ablation device (900). The pull wire (940) can be coupled to an internal position within the shaft of the ablation device (900), for example, between the proximal electrode (913) and the distal electrode (920). For example, the pull wire 940 can be attached near the proximal electrode 913, near the distal electrode 918, between the distal electrodes 918, 920, etc. In some embodiments, the pull wire (940) can be coupled to a handle mechanism or actuator (not shown) that a user can use 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 the location at which 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 the pull wire (940) is used to deflect a portion of the shaft, the shaft portion (924) may or may not deflect.

[0048] 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, subsets of electrodes (913, 915, 918, 920) may be wired in conjunction. For example, the proximal electrodes (913, 915) may be wired in conjunction using a single lead, and the distal electrodes (918, 920) may be wired in conjunction using a single lead. Alternatively, the distal tip electrode (920) may be independently addressable and wired using its own lead, the distal electrode (918) may be wired using its own lead, and the proximal electrodes (913, 915) may be wired in conjunction using a single lead. The insulation covering each lead may have sufficient dielectric strength to withstand a potential difference of between about 200V and about 2000V (including all subranges and values ​​therebetween) across its thickness without dielectric breakdown. In an 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.

[0049] Optionally, the sensor (950) can be incorporated into the distal portion 911 of the catheter, with one or more separate leads (not shown) attached to the sensor (950). The sensor (950) can be used, for example, to enable tracking of the position, orientation, etc. of the ablation device (900) in an anatomical structure (e.g., a cardiac chamber). For example, the sensor (950) can be an electromagnetic sensor that can receive electromagnetic signals from a transmitter coil associated with a position tracking system (e.g., tracking system (140)). The transmitter coil can be configured to generate a time-varying field that is received by the sensor (950) as a signal (e.g., a voltage, a current, or both). In some embodiments, one or more electrodes (913, 915, 918, 920) or another electrode (not depicted) can be used to receive electrocardiogram (ECG) data that can provide diagnostic information or be used to assess position. For example, the distal electrodes (918, 920) can be used to collect ECG data that can be displayed as a bipolar (differential) signal on a display associated with the ECG system. Additionally or alternatively, the electrodes (913, 915, 918, 920) can be used to sense signals from an impedance localization system for tracking the ablation device (900). Using the tracked position information, a visual representation of the ablation device (900) can be displayed in an electroanatomical or anatomical map, for example to provide a spatial scene for visualizing the location of the catheter.

[0050] According to the methods described herein, an ablation device (900) can be used to generate an ablation zone in a tissue by applying a high voltage waveform for pulsed electric field ablation, thereby generating an ablated tissue zone via irreversible electroporation. The ablation device (900) is operably coupled to a signal generator (e.g., a signal generator (122)), which can be used to deliver irreversible electroporation ablation to a tissue site. The signal generator can generate one or more pulse waveforms applied between electrodes (913, 915, 918, 920) configured as anode and cathode sets. For example, a distal electrode set (918, 920) and a proximal electrode set (913, 915) can be paired as an anode-cathode pair to generate damage via irreversible electroporation. In other words, the distal electrode set (918, 920) can be activated with a first polarity and the proximal electrode set (913, 915) can be activated with a second polarity opposite to the first polarity, so that the electrodes (913, 915, 918, 920) collectively generate an electric field that ablates a tissue site. When the electrodes (913, 915, 918, 920) are so paired and energized with an appropriate voltage pulse waveform of appropriate amplitude, the electrodes (913, 915, 918, 920) can generate an ablation zone having a depth that is generally independent of the orientation of the electrodes (913, 915, 918, 920) relative to the tissue, as described below with reference to Figures 5 to 8This pairing scheme enables the creation of lesions with depths that are generally independent of catheter orientation.

[0051] In some embodiments, the shaft of the ablation device (900) can have a diameter between about 4 French (1.33 mm) and about 15 French (5 mm). In some embodiments, each distal electrode (918, 920) can have the same length, such as length L1', and each proximal electrode (913, 915) can have the same length, such as 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 substantially equal to, greater than, or 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 combined length of the distal electrodes (918, 920) can be substantially equal to, greater than, or less than the combined length of the proximal electrodes (913, 915). The proximal electrodes (913, 915) may be separated from each other by a distance D2', and the distal electrodes (918, 920) may be separated from each other by a distance D3'. In some embodiments, the distance D2' separating the proximal electrodes (913, 915) may be substantially equal to, greater than, or less than the distance D3' separating the distal electrodes (918, 920). In some embodiments, the distances D2' and D3' may be less than the distance D1' separating the distal electrode 918 from the proximal electrode 915. The distances D1', D2', and D3' may generally be within a range between 0.5 mm and 12 mm. In some embodiments, the ratio D2' / D1' may be within a range between 1 and 20.

[0052] Fig.10A distal portion of an ablation device (1000) is schematically depicted. The ablation device (1000) may be and / or include components that are 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) that includes a distal electrode set (1018, 1020, 1022) and a proximal electrode set (1013, 1015). The distal electrode set (1018, 1020, 1022) may be separated from the proximal electrode set (1013, 1015) by a shaft portion (1024). In some embodiments, the shaft portion 1024 may be flexible, while in alternative embodiments, the shaft portion 1024 may be rigid or substantially rigid. A pull wire (1040) may be disposed within the ablation device (1000) for deflecting the ablation device (1000). The pull wire (1040) can be coupled to an internal location within the shaft of the ablation device (1000), for example, between the proximal electrode (1013) and the distal electrode (1022). For example, the pull wire 1040 can be attached near the proximal electrode 1013, near 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 a user can use 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 at which 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), the shaft portion (1024) may or may not deflect when the pull wire (1040) is used to deflect a portion of the shaft.

[0053] 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 electrodes (1013, 1015, 1018, 1020, 1022) may be wired in conjunction. For example, the proximal electrodes (1013, 1015) may be wired in conjunction with a single lead and the distal electrodes (1018, 1020, 1022) may be wired in conjunction with a single lead. Alternatively, the distal tip electrode (1022) may be independently addressable and wired with its own lead, the distal electrodes (1018, 1020) may be wired in conjunction with a single lead, and the proximal electrodes (1013, 1015) may be wired in conjunction with a single lead. The insulation covering each lead may have sufficient dielectric strength to withstand a potential difference of between about 200V and about 2000V (including all subranges and values ​​therebetween) across its thickness without dielectric breakdown. In an embodiment, the insulation covering each lead may have sufficient dielectric strength to withstand a potential difference of at least about 700V without dielectric breakdown.

[0054] Optionally, the sensor (1050) can be incorporated into the distal portion 1011 of the catheter, with one or more separate leads (not shown) attached to the sensor (1050). The sensor (1050) can be used, for example, to enable tracking of the position, orientation, etc. of the ablation device (1000) in an anatomical structure (e.g., a cardiac chamber). For example, the sensor (1050) can be an electromagnetic sensor that can receive electromagnetic signals from a transmitter coil associated with a position tracking system (e.g., tracking system (140)). In some embodiments, one or more electrodes (1013, 1015, 1018, 1020, 1022) or another electrode (not shown) can be used to receive ECG data that can provide diagnostic information or be used to assess location. For example, the distal electrodes (1018, 1020) can be used to collect ECG data that can be displayed as a bipolar (differential) signal on a display associated with the ECG system. Additionally or alternatively, electrodes (1013, 1015, 1018, 1020, 1022) can be used to sense signals from an impedance localization system for tracking the ablation device (1000). Using the tracked position information, a visual representation of the ablation device (1000) can be displayed in an electroanatomical map or an anatomical map, for example to provide a spatial scene for visualizing the location of a catheter.

[0055] According to the methods described herein, an ablation device (1000) can be used to generate an ablation zone in a tissue by applying a high voltage waveform for pulsed electric field ablation, thereby generating an ablated tissue zone via irreversible electroporation. The ablation device (1000) is operably coupled to a signal generator (e.g., a signal generator (122)), which can be used to deliver irreversible electroporation ablation to a tissue site. The signal generator can generate one or more pulse waveforms applied between electrodes (1013, 1015, 1018, 1020, 1022) configured as anode and cathode sets. For example, a distal electrode set (1018, 1020, 1022) and a proximal electrode set (1013, 1015) can be paired as an anode-cathode pair to generate damage via irreversible electroporation. When the electrodes (1013, 1015, 1018, 1020, 1022) are so paired and energized with an appropriate voltage pulse waveform of suitable amplitude, the electrodes (1013, 1015, 1018, 1020, 1022) can generate an ablation zone having a depth that is generally independent of the orientation of the electrodes (1013, 1015, 1018, 1020, 1022) relative to the tissue, as described below with reference to Figures 5 to 8 As further described.

[0056] Figures 5 to 8 Depicted are different ablation zones that may be created in tissue using the systems, devices, and methods described herein. Figure 5 A simulation of an ablation zone that can be generated in a tissue wall (560) using an ablation device (500) is depicted. 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).

[0057] like Figure 5 As depicted, the distal tip electrode 519 can be juxtaposed approximately normal to a tissue wall 560 (e.g., a cardiac tissue wall). In other words, the distal portion of the body (511) of the ablation device (500), including at least the distal tip electrode (519), can be positioned to extend in a direction approximately normal to the surface of the tissue wall (560). The distal portion of the body (511) can generally be disposed in a blood pool (550) adjacent to the tissue wall (560), such as a blood pool within a cardiac chamber. The tissue wall (560) can have a thickness in the range of about 1 mm to about 8 mm (including all values ​​and subranges therebetween).

[0058] According to the methods described herein, a pulse waveform may be generated, for example, using a signal generator (e.g., signal generator (122)) and delivered to the ablation device (500). Figure 5 In the simulated ablation zone (570) depicted in FIG, 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 to the first polarity. For example, the signal generator can be configured to deliver output signals associated with a pulse waveform and 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 an 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 (e.g., 1 kV) to generate a pulsed electric field having an ablation zone (570).

[0059] Figure 6 A simulation of an ablation zone generated in a tissue wall (660) using an ablation device (600) in an orientation that is tilted relative to the tissue wall (660) is depicted. The ablation device (600) can 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) can include a body (611), a distal tip electrode (619), and proximal electrodes (621, 623).

[0060] like Figure 6As depicted, the distal tip electrode (619) can be juxtaposed at an angle (e.g., between about 0 degrees and about 90 degrees, including all subranges and values ​​therebetween) relative to the tissue wall (660). The distal portion of the ablation device (600) can be positioned in the blood pool (650). The tissue wall (660) can have a thickness in the range of 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., where the tip electrode (619) has one electrical polarity and the proximal electrodes (621, 623) have the opposite electrical polarity), the electrodes (619, 621, 623) can generate a pulsed electric field having an ablation zone (670). When comparing the ablation zone (670) generated by the tilted juxtaposed ablation device (600) and the ablation zone (570) generated by the normally juxtaposed ablation device (500), the depth of the ablated tissue zone is similar. Specifically, the ablation zone (670) generated by the obliquely juxtaposed ablation device (600) has a depth that is approximately equal to the depth of the ablation zone (570) generated by the normally juxtaposed ablation device (500). Thus, the ablation devices described herein (e.g., ablation devices (500, 600)) can generate ablation zones in an orientation-independent manner.

[0061] Devices and systems as described herein can generate a controllable ablation zone in an orientation-independent manner, wherein the pulse waveform has a range of voltage amplitudes, for example, ranging from about 400V, about 1000V, about 5000V, about 10000V, about 15000V (including all values ​​and sub-ranges therebetween). As an example, Figure 7 and Figure 8 Describes the use of Figure 5 and Figure 6 The voltage of the higher voltage pulse waveform generates the simulated ablation zone (770, 870). For example, Figure 7 and Figure 8 The ablation device (700, 800) depicted in can be excited using a pulse waveform having a voltage amplitude of 2 kV.

[0062] Figure 7 A simulated ablation zone 770 is depicted generated in a tissue wall 760 using an ablation device 700 juxtaposed approximately normal to the tissue wall 760. The ablation device (700) can 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) can include a body (711), a distal tip electrode (719), and proximal electrodes (721, 723).

[0063] like Figure 7As depicted, the distal tip electrode (719) can be juxtaposed approximately normal (e.g., approximately 90 degrees) relative to the tissue wall (760). The distal portion of the ablation device (700) can be positioned in the blood pool (750). The tissue wall (760) can have a thickness ranging from approximately 1 mm to approximately 8 mm. Using a pulse waveform having an amplitude of 2 kV for each pulse and with the tip electrode (719) and the proximal electrodes (721, 723) being oppositely polarized, the electrodes (719, 721, 723) can generate a pulsed electric field having an ablation zone (770). As shown, due to the higher voltage of the pulse waveform, the ablation zone (770) can have a depth greater than the depth of the ablation zone (570, 670).

[0064] Figure 8 A simulated ablation zone (870) generated in a tissue wall (860) using an ablation device (800) juxtaposed obliquely relative to the tissue wall (860) is depicted. The ablation device (800) can 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) can include a body (811), a distal tip electrode (819), and proximal electrodes (821, 823).

[0065] like Figure 8 As depicted, the distal tip electrode (819) can be juxtaposed obliquely (e.g., between about 0 degrees and about 90 degrees, including all subranges and values ​​therebetween) relative to the tissue wall (860). The distal portion of the ablation device (800) can be positioned in the blood pool (850). The tissue wall (860) can have a thickness in the range of about 1 mm to about 8 mm. Using a pulse waveform having individual pulses with an amplitude of 2 kV and with the tip electrode (819) and the proximal electrodes (821, 823) being oppositely polarized, the electrodes (819, 821, 823) can generate a pulsed electric field having an ablation zone (870). As shown, due to the higher voltage of the pulse waveform, the ablation zone (870) can have a depth that is greater than the depth of the ablation zone (570, 670). When compared with Figure 7 ablation zone (870) has a similar depth (e.g., approximately the same depth) when compared to ablation zone (770) of FIG. Figure 7 and Figure 8 Additional examples of ablation devices described herein that are capable of generating a controllable ablation zone independent of the orientation of the ablation device relative to a tissue wall are provided.

[0066] It should be understood that the tip of the ablation catheter of the present invention may be juxtaposed at the tissue surface in any orientation convenient in clinical applications, whether normal, oblique, or tangential to the local tissue surface.The specific examples provided herein are given for illustrative purposes only.

[0067] As used herein, the terms "about" and / or "approximately" when used in conjunction with numerical values ​​and / or ranges generally refer to those numerical values ​​and / or ranges that are close to the stated numerical values ​​and / or ranges. In some cases, the terms "about" and "approximately" can mean within ±10% of the stated value. For example, in some cases, "about 100 [units]" may mean within ±10% of 100 (e.g., from 90 to 110). The terms "about" and "approximately" can be used interchangeably.

[0068] 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.

[0069] Some embodiments described herein relate to computer storage products with non-transitory computer-readable media (also referred to as non-transitory processor-readable media) having thereon instructions or computer codes for performing various computer-implemented operations. Computer-readable media (or processor-readable media) are non-transitory in the sense that they do not include transient propagating signals themselves (e.g., propagating electromagnetic waves that carry information on a transmission medium such as space or cables). The media and computer codes (also referred to as codes or algorithms) may be those designed and constructed for one or more specific 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 memories (CD-ROMs), and holographic devices; magneto-optical storage media such as optical disks; carrier signal processing modules; and hardware devices specially configured to store and execute program codes, such as application-specific integrated circuits (ASICs), programmable logic devices (PLDs), read-only memories (ROMs), and random-access memories (RAMs) devices. Other embodiments described herein relate to a computer program product, which may include, for example, the instructions and / or computer code disclosed herein.

[0070] The systems, devices and / or methods described herein may be implemented by software (implemented on hardware), hardware or a combination thereof. Hardware modules may include, for example, a general purpose processor (or microprocessor or microcontroller), a field programmable gate array (FPGA) and / or an application specific integrated circuit (ASIC). Software modules (implemented on hardware) may be expressed in various software languages ​​(e.g., computer code), including C, C++, Ruby, Visual 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 produced by a compiler, code for generating network services, and files containing high-level instructions executed by a computer using an interpreter. Additional examples of computer code include, but are not limited to, control signals, encrypted code, and compressed code.

[0071] The specific examples and descriptions herein are exemplary in nature and one skilled in the art may develop embodiments based on the teachings herein without departing from the scope of the present invention, which is limited solely by the appended claims.

Claims

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

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

3. The system of claim 2, wherein the distal electrode set comprises at least one distal tip electrode disposed at the tip of the linear shaft.

4. The system of claim 2, wherein the distal electrode set comprises: a distal tip electrode disposed at a tip of the linear shaft; as well as One or more distal electrodes are disposed proximate to the distal tip electrode, and a third length of the linear axis separates the distal tip electrode from an adjacent distal electrode of the one or more distal electrodes.

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

6. A system according to claim 4, wherein the two proximal electrodes are jointly wired 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 distal electrodes are independently or jointly wired 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 being 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 about 0.5 mm to about 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 about 1 and about 20.

10. The system of claim 1, further comprising: a tracking device configured to track a position of a distal portion of the linear shaft during positioning, the tracking device comprising a field generator configured to generate at least one of an electric field or a magnetic field, The ablation device also includes a sensor disposed on the distal portion, the sensor configured to receive a set of signals in response to the generated field for determining a position of the distal portion of the linear shaft.

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