Electroporation with cooling

Abstract

The invention is entitled "Electroporation with Cooling". A medical system is disclosed, the medical system comprising a catheter comprising: an insertion tube having a distal end; an elongate resilient distal segment secured to the distal end of the insertion tube, the distal segment having an outer surface; and a plurality of electrode structures, each electrode structure disposed on and protruding from the outer surface of the distal segment, each electrode structure comprising a respective primary electrode and at least one respective secondary electrode extending around the outer surface, and a respective electrically insulating material disposed around the outer surface and between the respective primary electrode and the at least one respective secondary electrode, the respective primary electrode protruding from the outer surface to a greater extent than the at least one respective secondary electrode and the respective electrically insulating material.

Description

Technical Field

[0001] This invention relates to medical systems, and specifically, but not exclusively, to catheter devices. Background Technology

[0002] Numerous medical procedures involve placing probes, such as catheters, inside a patient's body. Position sensing systems have been developed to track these probes. Magnetic position sensing is one method known in the art. In magnetic position sensing, a magnetic field generator is typically placed at a known location outside the patient's body. A magnetic field sensor within the distal end of the probe generates electrical signals in response to these magnetic fields; these signals are processed to determine the coordinate position of the distal end of the probe. These methods and systems are described in U.S. Patents 5,391,199, 6,690,963, 6,484,118, 6,239,724, 6,618,612, and 6,332,089, in PCT International Patent Publication WO 1996 / 005768, and in U.S. Patent Application Publications 2002 / 006455, 2003 / 0120150, and 2004 / 0068178. Impedance- or current-based systems can also be used to track position.

[0003] Treatment of arrhythmias is a medical procedure in which these types of probes or catheters have proven extremely useful. Arrhythmias, and specifically atrial fibrillation, have always been a common and dangerous medical condition, especially in the elderly.

[0004] The diagnosis and treatment of cardiac arrhythmias involve mapping the electrical properties of cardiac tissue, particularly the endocardium, and selectively ablating cardiac tissue by applying energy. Such ablation can stop or alter unwanted electrical signals propagating from one part of the heart to another. Ablation methods disrupt unwanted electrical pathways by creating a non-conductive ablation focus. Various forms of energy delivery for creating ablation focuses have been disclosed, including the use of microwaves, lasers, and more commonly, radiofrequency energy to create conduction blocks along the cardiac tissue walls. In a two-step procedure (mapping followed by ablation), electrical activity at various points within the heart is typically sensed and measured by advancing a catheter containing one or more electrical sensors into the heart and acquiring data at multiple points. This data is then used to select the target endocardial region for ablation.

[0005] Electrode catheters have been widely used in medical practice for many years. They are used to stimulate and map electrical activity in the heart, as well as to ablate sites of abnormal electrical activity. In use, the electrode catheter is inserted into a major vein or artery, such as the femoral vein, and then guided to the desired cardiac chamber. A typical ablation procedure involves inserting a catheter with one or more electrodes at its distal end into the cardiac chamber. A reference electrode can be provided, typically taped to the patient's skin, or a second catheter positioned in or near the heart can be used to provide the reference electrode. RF (radio frequency) current is applied through the distal electrode of the ablation catheter, and the current flows through the medium surrounding the distal electrode—the blood and tissue between the distal and unrelated electrodes. The current distribution depends on the amount of contact between the electrode surface and the tissue compared to blood, which has a higher conductivity than tissue. Heating of the tissue occurs due to its resistance. The tissue is sufficiently heated to destroy cells in the cardiac tissue, resulting in the formation of a non-conductive ablation focus within the cardiac tissue.

[0006] U.S. Patent Publication 2010 / 0168548 to Govari et al. describes a cardiac catheter including a lasso catheter for use in an electrical mapping system of the heart. The catheter has an array of raised, perforated electrodes in fluid communication with a flushing lumen. Position sensors are located on the distal loop portion and the proximal base portion of the catheter. The electrodes are sensing electrodes suitable for pacing or ablation. The raised electrodes securely contact cardiac tissue, thereby forming an electrical connection with very low resistance.

[0007] U.S. Patent 2012 / 0310065 to Falwell et al. describes an apparatus and method for mapping electrical activity within the heart, creating a lesion (ablation) in cardiac tissue to produce a region of necrotic tissue, the region of necrotic tissue being able to prevent the propagation of erroneous electrical impulses caused by arrhythmias.

[0008] U.S. Patent Publication 2016 / 0324575 to Panescu et al. describes a medical device (e.g., an ablation device) comprising an elongated body having a proximal end and a distal end; an energy delivery member positioned at the distal end of the elongated body; a first plurality of temperature measuring devices carried by or positioned within the energy delivery member, the first plurality of temperature measuring devices being thermally insulated from the energy delivery member; and a second plurality of temperature measuring devices positioned adjacent to the proximal end of the energy delivery member, the second plurality of temperature measuring devices being thermally insulated from the energy delivery member.

[0009] U.S. Patent 6,416,505 to Fleischman et al. describes surgical methods and devices for positioning diagnostic or therapeutic elements within the body. The device may be catheter-based or include a probe with a relatively short axis.

[0010] U.S. Patent 6,482,202 to Goble et al. describes an electrosurgical instrument for treating tissue in the presence of a conductive fluid medium, and includes an instrument shaft and an electrode assembly at one end of the shaft. The electrode assembly includes a tissue treatment electrode and a return electrode, the return electrode being electrically insulated from the tissue treatment electrode by means of an insulating member. The tissue treatment electrode has an exposed end for treating tissue, and the return electrode has a fluid contact surface spaced apart from the tissue treatment electrode in use in a manner defining a conductive fluid path that connects a circuit between the tissue treatment electrode and the return electrode. The electrode assembly provides a plurality of orifices in the region of the tissue treatment electrode through which vapor bubbles and / or particulate matter can be aspirated from the region surrounding the tissue treatment electrode. Summary of the Invention

[0011] According to an embodiment of the present invention, a medical system is provided, the medical system comprising a catheter including: an insertion tube having a distal end; an elongated, resilient distal segment fixed to the distal end of the insertion tube, the distal segment having an outer surface; and a plurality of electrode structures, each electrode structure disposed on and protruding from the outer surface of the distal segment, each electrode structure including a respective primary electrode extending around the outer surface and at least one respective secondary electrode, and a respective electrically insulating material disposed around the outer surface and located between the respective primary electrode and the at least one respective secondary electrode, the respective primary electrode protruding from the outer surface to a greater extent than the at least one respective secondary electrode and the respective electrically insulating material.

[0012] Additionally, according to one embodiment of the invention, the insertion tube is configured for insertion through a blood vessel into the heart of the subject, and wherein, when the resilient distal segment is deployed within the heart, the resilient distal segment defines a collar and is configured to open and close the collar.

[0013] In addition, according to one embodiment of the invention, the diameter of the collar is between 5 mm and 35 mm.

[0014] In addition, according to one embodiment of the invention, the corresponding primary electrode includes a metal ring, and at least one corresponding secondary electrode includes at least one metal ring, the corresponding primary electrode and the at least one corresponding secondary electrode being connected by a corresponding electrical insulating material.

[0015] Furthermore, according to one embodiment of the invention, at least one corresponding secondary electrode comprises two corresponding electrodes.

[0016] Furthermore, according to an embodiment of the present invention, the two corresponding electrodes are disposed on either side of the corresponding primary electrode.

[0017] Furthermore, according to an embodiment of the present invention, the distal segment has an elongation direction, the corresponding primary electrode has a first width measured parallel to the elongation direction, and each of the two corresponding electrodes has a second width measured parallel to the elongation direction, the first width being greater than the second width.

[0018] Furthermore, according to one embodiment of the invention, the first width is at least twice the size of the second width.

[0019] Furthermore, according to one embodiment of the invention, the first width is in the range of 2 mm to 8 mm, and the second width is in the range of 0.1 mm to 1 mm.

[0020] Furthermore, according to an embodiment of the invention, the distal segment has an elongation direction, and each electrode structure has a width between 2.5 mm and 10 mm measured parallel to this elongation direction.

[0021] In addition, according to an embodiment of the present invention, each electrode structure includes a corresponding thermally conductive material disposed below the corresponding primary electrode and located between the corresponding primary electrode and the outer surface of the distal segment.

[0022] In addition, according to one embodiment of the present invention, the corresponding thermally conductive material is formed of a material different from that of the corresponding primary electrode.

[0023] Furthermore, according to one embodiment of the invention, the corresponding thermally conductive material and the corresponding primary electrode are formed into a single unit, the mass of which is greater than twice the mass of at least one corresponding secondary electrode.

[0024] Additionally, according to one embodiment of the invention, the system includes a signal generator configured to generate a pulse signal that will be applied to cardiac tissue by a corresponding primary electrode to perform electroporation of the cardiac tissue.

[0025] Additionally, according to one embodiment of the invention, the system includes an intracardiac electrogramming (IEGM) module configured to receive at least one signal sensed by at least one corresponding secondary electrode and generate an IEGM for output to a display device.

[0026] According to another embodiment of the present invention, a medical system is also provided, the medical system comprising a catheter including: an insertion tube having a distal end; an elastic elongated distal segment fixed to the distal end of the insertion tube, the distal segment having an outer surface; a plurality of electrode structures disposed on and protruding from the outer surface of the distal segment; and a thermally conductive material disposed below the electrode structures and between each electrode structure in the electrode structures and the outer surface of the distal segment, wherein the thermally conductive material is formed of a material different from the electrode structures.

[0027] Additionally, according to one embodiment of the invention, the insertion tube is configured for insertion through a blood vessel into the heart of the subject, and wherein, when the resilient distal segment is deployed within the heart, the resilient distal segment defines a collar and is configured to open and close the collar.

[0028] Furthermore, according to one embodiment of the invention, the diameter of the collar is between 5 mm and 35 mm.

[0029] Additionally, according to one embodiment of the invention, the system includes a signal generator configured to generate a pulse signal that will be applied to cardiac tissue by an electrode structure to perform electroporation of the cardiac tissue.

[0030] According to another embodiment of the invention, a medical method is also provided, the method comprising providing a catheter and converting the catheter for electroporation, the catheter comprising: an insertion tube having a distal end; a resilient distal segment fixed to the distal end of the insertion tube, the distal segment having an outer surface and an inner flushing cavity; and a plurality of electrode structures protruding from the outer surface, the electrode structures having a plurality of perforations formed therethrough, the electrode structures defining a corresponding hollow segment between a corresponding electrode structure in the electrode structure and the outer surface, the perforations being in fluid communication with the flushing cavity via the hollow segment, and converting the catheter for electroporation by injecting a thermally conductive material into the hollow segment via the perforations of the electrodes. Attached Figure Description

[0031] The invention will be understood from the following detailed description taken in conjunction with the accompanying drawings, wherein:

[0032] Figure 1 A schematic diagram of a medical system constructed and operated according to an exemplary embodiment of the present invention;

[0033] Figure 2 A schematic diagram of a sling conduit in a closed configuration constructed and operated according to an exemplary embodiment of the present invention;

[0034] Figure 3 for Figure 2A schematic diagram of the lasso conduit in an open configuration;

[0035] Figures 4A to 4D It is along Figure 3 A sectional view of the alternative electrode structure of the sling cannula, taken from line A:A.

[0036] Figure 5 A schematic diagram of an alternative sling catheter constructed and operated according to an exemplary embodiment of the present invention; and

[0037] Figure 6 It is along Figure 5 A cross-sectional view of the electrode structure of the sling conduit, taken from line B:B. Detailed Implementation

[0038] SUMMARY

[0039] Some catheters provide flushing via orifices in the catheter electrode, such as Biosense Webster's (Irvine, California) nMARQ. TM The nMARQ catheter is a lasso-shaped radiofrequency (RF) ablation catheter comprising electrodes positioned along a lasso cannula, with an opening for flushing from the region of the electrode (e.g., below the electrode) within the lasso cannula. Providing flushing not only reduces heat but also dilutes the blood to prevent its coagulation during RF ablation. Each electrode of the nMARQ protrudes from the surface of the lasso cannula to ensure that the electrode protrudes above polyurethane, which is used to secure the electrode to the cannula at its edge, thereby achieving proper contact between the electrode and cardiac tissue. The electrodes also have a uniform wall thickness, so that as the electrode center protrudes outward, there is a corresponding hollow segment between the cannula of the lasso and the inner surface of the electrode. The hollow segment allows flushing fluid to be pumped to the hollow segment to cool the electrode and exit through a hole in the electrode.

[0040] If the same electrode is used without rinsing (e.g., for electroporation), any heat generated in the air gap between the inner surface of the electrode and the tube (e.g., through electroporation) will not dissipate easily because air is a very poor conductor of heat and the thin walls of the electrode do not provide a large amount of heat capacity. Therefore, even if electroporation does not generate excessive heat, undesirable localized temperature rises may still occur.

[0041] Exemplary embodiments of the present invention address the aforementioned problems by providing a catheter having a resilient distal segment (e.g., a formable collar) with an electrode structure disposed thereal. The electrode structure protrudes from the outer surface of the distal segment and includes additional thermally conductive material to enhance cooling and increase heat capacity during procedures such as electroporation. The thermally conductive material may be a filler material placed beneath the electrode of the electrode structure, which is a different material from the rest of the electrode structure. For example, the filler may be a metal (such as platinum) or a non-metal (such as a thermally conductive epoxy resin). In other exemplary embodiments, the central protruding portion of the electrode structure may be configured to be thicker than the sides of the electrode structure, such that the thicker central segment of the electrode structure provides thermally conductive material (i.e., the electrode itself) to enhance cooling during procedures such as electroporation.

[0042] As used in the specification and claims, the term "thermal conductive material" is defined as a material with a thermal conductivity greater than or equal to 1 watt per meter Kelvin (W / mK) at 25 degrees Celsius.

[0043] Another issue associated with electroporation is the need to provide electrodes large enough to apply the current for the electroporation pulse. Using the same large electrodes favored for electroporation for sensing may not be ideal, for example, for sensing cardiac electrical activity (e.g., intracardiac electrogram (IEGM) or for sensing position signals using current- or impedance-based position tracking systems), because the large electrodes may introduce excessive noise into the sensed signal or provide inaccurate spatial information due to their size. Providing multiple large electrodes for electroporation and smaller electrodes for sensing along the distal segment of the catheter can make the distal segment too inflexible.

[0044] Exemplary embodiments of the present invention address the aforementioned problems by providing corresponding electrode structures within an electrode structure having a primary electrode for electroporation and one or more secondary electrodes and a smaller electrode for sensing. Providing electrodes for electroporation and sensing on the same electrode structure allows for the combination of electroporation and sensing functions on the catheter, but limits the number of such structures on the distal segment, thereby allowing the distal segment to maintain sufficient flexibility. In some exemplary embodiments, each electrode structure may include two secondary electrodes that can be placed on either side of the primary electrode and can be used to sense position signals, IEMM, etc. The primary and secondary electrodes may be electrically isolated from each other using a suitable electrically insulating material (e.g., epoxy or any suitable polymer). In some exemplary embodiments, a thermally conductive material may be placed below the primary electrode to provide heat dissipation and heat capacity. In other exemplary embodiments, the primary electrode may be formed to be thicker than the secondary electrode, such that the thicker electrode provides at least some heat dissipation. The primary and secondary electrodes may be formed as a ring extending around the distal segment of the catheter and connected together using an electrically insulating material. In other exemplary embodiments, the ring of thermally conductive material may be formed around a distal segment, wherein a primary electrode is positioned above the thermally conductive ring, and a secondary electrode is positioned on either side of the thermally conductive ring. Many other configurations are also possible, and some configurations are described below with reference to the disclosed exemplary embodiments.

[0045] As used in the specification and claims, the term "electrically insulating material" is defined as a material having a volume resistivity of more than one million Ωcm at 20 degrees Celsius.

[0046] An exemplary embodiment of the present invention provides a medical system comprising a catheter. The catheter includes an insertion cannula and an elongated, flexible distal segment fixed to a distal end of the insertion cannula. The insertion cannula is inserted through a blood vessel into the heart of a patient. When the flexible distal segment is deployed within the heart, the flexible distal segment defines a collar and is configured to open and close the collar, for example, using an internal elastic member (such as a length of metal, like nitinol, that can be manipulated by a physician).

[0047] The catheter includes multiple electrode structures. Each electrode structure is positioned on and protrudes from the outer surface of a distal segment. Each electrode structure may include a primary electrode extending around the outer surface of the distal segment and one or more secondary electrodes, as well as an electrically insulating material disposed around the outer surface and located between each primary electrode and the corresponding secondary electrode. The primary electrode of each electrode structure protrudes from the outer surface to a greater extent than the secondary electrodes and the electrically insulating material of the electrode structure.

[0048] In some exemplary embodiments, the primary electrode includes a metal ring, and the secondary electrode includes one (or more) metal rings. The primary electrode and the corresponding secondary electrode (i.e., electrodes of the same structure) can be connected by an electrically insulating material.

[0049] In some exemplary embodiments, the secondary electrode includes two electrodes optionally disposed on either side of the corresponding primary electrode (i.e., the same electrode structure).

[0050] The distal segment has an elongation direction. Each primary electrode has a first width measured parallel to this elongation direction. Each secondary electrode has a second width measured parallel to this elongation direction. In some embodiments, the first width is greater than the second width.

[0051] Each electrode structure may include a corresponding thermally conductive material disposed below a respective primary electrode and between the respective primary electrode and the outer surface of a distal segment. In some exemplary embodiments, the thermally conductive material is formed of a different material than that of the primary electrode. In other exemplary embodiments, the thermally conductive material and the primary electrode are formed as a single unit. The single unit forming the primary electrode may have a mass greater than twice the mass of each secondary electrode.

[0052] The medical system may include a signal generator that generates pulse signals that are applied to cardiac tissue by one or more primary electrodes to perform electroporation of the cardiac tissue. The medical system may include an IEMG module configured to receive at least one signal sensed by secondary electrodes and generate an IEMG (or multiple IEMGs) for output to a display device.

[0053] In some exemplary embodiments, each electrode structure includes a single electrode having a thermally conductive material disposed beneath the electrode structure, between each electrode structure and the outer surface of a distal segment. This thermally conductive material is formed of a material different from that of the electrode structure.

[0054] In some exemplary embodiments, a flushing conduit can be converted for electroporation as described below. The method includes providing a conduit comprising an insertion tube and a resilient distal segment secured to a distal end of the insertion tube. The distal segment has an outer surface and an inner flushing cavity, and an electrode structure protruding from the outer surface. The electrode structure has a perforation formed therethrough, and the electrode structure defines a corresponding hollow segment between a corresponding electrode structure within the electrode structure and the outer surface. The perforation is in fluid communication with the flushing cavity via the hollow segment. The method includes converting the conduit for electroporation by injecting a thermally conductive material into the hollow segment via the perforation of the electrode, and typically, but not necessarily, the conduit provides flushing.

[0055] System Description

[0056] Now for reference Figure 1 The figure is a schematic diagram of a medical system 20 constructed and operated according to an exemplary embodiment of the present invention. Also referenced is... Figure 2 The figure is a schematic diagram of a lasso conduit 40 in a closed configuration constructed and operated according to an exemplary embodiment of the present invention.

[0057] System 20 includes a catheter 40 configured for insertion into a body portion of a living subject (e.g., patient 28). A physician 30 navigates the catheter 40 to a target location (illustration 25) in the heart 26 of patient 28 by manipulating a deflectable element of the insertion cannula 22 of the catheter 40 and / or deflecting it from a sheath 23 using a manipulator 32 located near the proximal end of the catheter 40. In this manner, or in any suitable way, the insertion cannula 22 is configured for insertion through a blood vessel into the heart of the subject. In the illustrated embodiment, physician 30 uses the catheter 40 to perform electroanatomical mapping of the cardiac chambers and ablation of cardiac tissue.

[0058] The catheter 40 includes an elongated, flexible distal segment 35 (e.g., an adjustable collar) inserted in a straight configuration through the sheath 23, and which only returns to its intended functional shape after the catheter 40 has been withdrawn from the sheath 23. By constraining the elongated, flexible distal segment 35 in a straight configuration, the sheath 23 also serves to minimize vascular trauma en route to its target location.

[0059] The catheter 40 includes multiple electrode structures 48 (only some are labeled for simplicity), which include electrodes for sensing electrical activity and / or applying ablation power and / or electroporation power to ablate and / or electroporate tissue in body parts. The catheter 40 may incorporate a magnetic sensor 50 at the distal edge of the insertion tube 22 (i.e., at the proximal edge of the elongated, flexible distal segment 35). Figure 2 (Seen in cross-section of the insertion tube 22 on the left). By way of example only, the magnetic sensor 50 may be a uniaxial sensor (SAS), a biaxial sensor (DAS), or a triaxial sensor (TAS), based on, for example, dimensional design considerations. The conduit 40 may also include one or more electrodes 52 disposed on the distal edge of the insertion tube 22, for example, on either side of the magnetic sensor 50. The electrodes 52, the magnetic sensor 50, and the electrodes of the electrode structure 48 disposed on the elongated, flexible distal segment 35 are connected to various drive circuits in the control console 24 via wires passing through the insertion tube 22.

[0060] In some exemplary embodiments, system 20 includes a magnetic sensing subsystem to estimate the position of the elongated, flexible distal segment 35 of catheter 40 within the heart chambers of heart 26. Patient 28 is placed in a magnetic field generated by a pad containing one or more magnetic field generator coils 42, driven by unit 43. The magnetic field generated by coils 42 transmits an alternating magnetic field to the area where the body portion is located. The transmitted alternating magnetic field generates a signal in magnetic sensor 50 indicating the position and / or orientation of the distal end of catheter 40. The generated signal is transmitted to console 24 and becomes a corresponding electrical input to processing circuitry 41.

[0061] In some exemplary embodiments, processing circuitry 41 uses position signals received from electrodes 52 and / or electrode structure 48 and / or magnetic sensor 50 to estimate the position of catheter 40 within an organ such as a heart chamber. In some embodiments, processing circuitry 41 correlates the position signals received from the electrodes with previously acquired magnetic position-calibration position signals to estimate the position of catheter 40 within the organ. The position coordinates of the electrodes may be determined by processing circuitry 41 based on (among other inputs) the ratio of a measured impedance or current distribution between the electrodes and the surface electrodes 49.

[0062] Position sensing methods utilizing current distribution measurements and / or external magnetic fields are implemented in various medical applications, for example, in products manufactured by Biosense Webster Inc (Irvine, California). The system is implemented and described in detail in U.S. Patent Nos. 5,391,199, 6,690,963, 6,484,118, 6,239,724, 6,618,612, 6,332,089, 7,756,576, 7,869,865 and 7,848,787, PCT Patent Publication WO 96 / 05768, and U.S. Patent Application Publications 2002 / 0065455 A1, 2003 / 0120150 A1 and 2004 / 0068178 A1.

[0063] 3. The system employs a position tracking method based on advanced conduit positioning (ACL) impedance. In some exemplary embodiments, processing circuitry 41 is configured to use the ACL method to generate a mapping between an indication of impedance and the position of the magnetic field generator coil 42 in a magnetic coordinate system (e.g., a current-position matrix (CPM)). Processing circuitry 41 estimates the position of the electrode by performing a lookup in the CPM.

[0064] Other methods may be used to determine the location of the distal end of catheter 40, such as based on an ultrasound transducer and receiver, using imaging techniques such as ultrasound or MRI or CT scans (which may include placing a radiopaque label on catheter 40).

[0065] Processing circuitry 41 (typically part of a general-purpose computer) is further connected via suitable front-end and interface circuitry 44 to receive signals from body surface electrodes 49. Processing circuitry 41 is connected to body surface electrodes 49 via wires that pass through cable 39 and extend to the chest of patient 28.

[0066] In some exemplary embodiments, the processing circuit 41 presents a representation 31 of at least a portion of the catheter 40 and the calibrated body portion to the display device 27 in response to the calculated position coordinates of the catheter 40.

[0067] The processing circuit 41 is typically programmed with software to perform the functions described herein. This software may be downloaded electronically to a computer via a network, or alternatively or additionally set and / or stored on a non-transitory tangible medium (such as magnetic storage, optical storage, or electronic storage).

[0068] The medical system 20 may also include a signal generator 54 (such as an RF signal generator) configured to be connected to the catheter 40 and to apply electrical signals to the electrodes of the electrode structure 48 to perform RF ablation and / or electroporation.

[0069] Figure 1 and Figure 2 The exemplary examples shown are chosen solely for the sake of conceptual clarity. For the sake of simplicity and clarity, Figure 1 Only elements relevant to the technology disclosed in this invention are shown. System 20 typically includes additional modules and elements that are not directly related to the technology disclosed in this invention, and therefore these additional modules and elements are derived from... Figure 1 The corresponding descriptions are intentionally omitted. The elements of system 20 and the methods described herein can be further applied, for example, to control the ablation / electroporation of tissues of the heart 26.

[0070] The medical system 20 is described with reference to a catheter 40 having a lasso-shaped, elongated, flexible distal segment 35. The catheter 40 can be implemented with an elongated, flexible distal segment 35 of any suitable shape, such as, but not limited to, a multi-spindle catheter.

[0071] Now for reference Figure 3 The image is Figure 2 A schematic diagram of the lasso conduit 40 in its open configuration. See also: Figure 2 .

[0072] The distal end 56 of the insertion tube 22 typically includes a deflectable segment and a distal edge comprising electrodes 52, with a magnetic sensor 50 disposed between the two electrodes. The distance between the centers of the two electrodes 52 can be any suitable distance, such as in the range of 5 mm to 20 mm, for example, 11 mm. The magnetic sensor 50 (e.g., a magnetic coil sensor) can be positioned at any suitable location. Figure 2 In the example, the magnetic sensor 50 is shown as the distal electrode closer to the electrode 52. The insertion tube 22 may have any suitable outer diameter, for example, in the range of 1 mm to 6 mm, such as 2.5 mm.

[0073] An elongated, flexible distal segment 35 is secured to the distal end 56 of the insertion cannula 22. The elongated, flexible distal segment 35 has an outer surface 58. The elongated, flexible distal segment 35 may be made of any suitable material, such as a flexible polymer, like polyurethane or polyether block amide. When deployed within the heart, the flexible distal segment 35 defines a collar and is configured to open and close (or tighten and loosen) the collar. As used in this specification and claims, the term "collar" is defined as the elongated, flexible distal segment 35 bending at least 180 degrees around a bend to form a closed bend, a partially overlapping bend, or a partially open loop.

[0074] The collar shape can be formed by an elastic or deflectable element, such as a nitinol ridge (not shown), disposed within the lumen of the elongated elastic distal segment 35, which allows the elongated elastic distal segment 35 to be inserted into the heart 26 ( Figure 1 The period is straight, and once the slender, elastic distal segment 35 leaves the sheath 23 ( Figure 1 This forms a collar. This can be achieved, for example, by using a manipulator 32 ( Figure 1 The elastic element is pulled to contract the collar. In some exemplary embodiments, the elongated elastic distal segment 35 may be formed as an inflatable element.

[0075] Open loop ( Figure 3 ) and closed loop ( Figure 2 The open loop can have any suitable diameter. In some exemplary embodiments, the open loop has a diameter between 10 mm and 35 mm, and the closed loop has a diameter between 5 mm and 25 mm. In some exemplary embodiments, the distal segment has an open diameter of 25.4 mm and a closed diameter of 15.24 mm.

[0076] Each electrode structure 48 is disposed on and protrudes from the outer surface 58 of the elongated resilient distal segment 35. The electrode structures 48 (some are only marked for simplicity) can be attached to the elongated resilient distal segment 35 using a suitable adhesive and / or polyurethane, which is used to secure the edges of the electrode structures 48 to the elongated resilient distal segment 35.

[0077] The catheter 40 may include any suitable number of electrode structures 48, depending on the width of each electrode structure 48, the length of the elongated, flexible distal segment 35, and the desired flexibility of the distal segment 35. Too many electrode structures 48 may make the distal segment 35 too inflexible. Figure 2 and Figure 3 Ten electrode structures 48 disposed on the distal segment are shown. In other exemplary embodiments, the number of electrode structures 48 disposed on the distal segment 35 may include any suitable number, for example, in the range of 4 to 30.

[0078] The electrode structures 48 may be spaced evenly or non-evenly along the distal segment 35. In some exemplary embodiments, the center-to-center spacing between the electrode structures 48, measured along an arc, is 7 mm, but any suitable value may be used, for example, in the range of 3 mm to 30 mm. The distance from the center of the distal electrode structure 48 to the end 60 of the distal segment 35 may be any suitable value, for example, in the range of 1 mm to 20 mm, such as 7 mm.

[0079] In some exemplary embodiments, such as illustration 66 (which shows along...) Figure 3 As shown in the cross-sectional view taken from line A:A, each electrode structure 48 includes an electrode 62, wherein a thermally conductive material 64 is disposed between the electrode 62 and the outer surface 58. The thermally conductive material 64 can be any suitable thermally conductive material, such as, but not limited to, platinum, palladium, gold, or thermally conductive epoxy resin. In some exemplary embodiments, the thermally conductive material 64 is first wrapped around the outer surface 58 of the elongated, resilient distal segment 35, and then the electrode 62 is wrapped around the thermally conductive material 64. In other exemplary embodiments, the electrode 62 is first fixed around the outer surface 58 (as a single piece or from two halves subsequently joined together), and then the thermally conductive material 64 is injected beneath the electrode 62 through a hole (not shown) in the electrode 62.

[0080] Now for reference Figures 4A to 4D The diagram is along Figure 3 A: A sectional view of the alternative electrode structure 48 of the sling conduit 40, taken from line A:A. Shown in... Figures 4A to 4D The common features of the various electrode structures 48 are first described below.

[0081] Each electrode structure 48 includes a corresponding primary electrode 68 extending around an outer surface 58 and at least one corresponding secondary electrode 70. Each electrode structure 48 also includes a corresponding electrically insulating material 72 disposed around the outer surface 58 and located between the corresponding primary electrode 68 and the corresponding secondary electrode 70. The term "corresponding" is used with reference to the primary electrode 68, secondary electrode 70, and electrically insulating material 72 to describe the primary electrode 68, secondary electrode 70, and electrically insulating material 72 of the same electrode structure 48. The corresponding primary electrode 68 protrudes from the outer surface 58 to a greater extent than the corresponding secondary electrode 70 and the corresponding electrically insulating material 72.

[0082] In some exemplary embodiments, each electrode structure 48 includes two secondary electrodes 70 optionally disposed on either side of the respective primary electrode 68.

[0083] As previously mentioned, an issue associated with electroporation is the need to provide electrodes large enough to apply the current for the electroporation signal. Using the same large electrode for sensing, which is advantageous for electroporation, may not be ideal, for example, for sensing cardiac electrical activity (e.g., intracardiac electrogram (IEGM) or for sensing position signals using a current- or impedance-based position tracking system), because the large electrode may introduce excessive noise into the sensed signal. Providing multiple large electrodes for electroporation and smaller electrodes for sensing along the distal segment of the catheter can make the distal segment too inflexible. Therefore, in some exemplary embodiments, each second electrode 70 is typically narrower than the first electrode 68, allowing the primary electrode 68 to be used for electroporation and the secondary electrode 70 for sensing. Because the primary electrode 68 and the secondary electrode 70 are included in a single structure of electrode structure 48, a large electrode for electroporation and a smaller electrode for sensing can be provided along the distal segment 35 of the catheter 40 without making the catheter 40 too inflexible.

[0084] In some exemplary embodiments, signal generator 54 ( Figure 1 The system is configured to generate a pulse signal that will be applied to cardiac tissue by one or more primary electrodes in primary electrodes 68 to perform electroporation of the cardiac tissue. In some embodiments, the medical system 20 includes an intracardiac electrogrammography (IEGM) module 74. Figure 1 The intracardiac electrogram module is configured to receive at least one signal sensed by one or more secondary electrodes in the secondary electrodes 70 and generate one or more IEGGMs for output to the display device 27. Figure 1 ).

[0085] In some exemplary embodiments, each primary electrode 68 and each secondary electrode 70 is formed of a metal strip that wraps around the outer surface 58 of an elongated, resilient distal segment 35, thereby forming a corresponding metal ring. In other embodiments, each primary electrode 68 and each secondary electrode 70 may be formed of a semi-ring joined together around the outer surface 58. The primary electrode 68 and secondary electrode 70 of one electrode structure in electrode structure 48 may be connected together by an electrically insulating material 72. The electrically insulating material 72 may also be used as an adhesive to glue the primary electrode 68 to the secondary electrode 70. In other exemplary embodiments, a suitable adhesive may be used to connect the primary electrode 68, the secondary electrode 70, and the electrically insulating material 72.

[0086] In some exemplary embodiments, a material retainer (or multiple material retainers) may be used to hold the primary electrode 68 to the secondary electrode 70. An electrically insulating material 72 (e.g., epoxy resin) may then be added between the primary electrode 68 and the secondary electrode 70 to further adhere the primary electrode 68 to the secondary electrode 70. After the electrically insulating material 72 has been applied, the retainer may be removed.

[0087] In some exemplary implementations (see) Figure 4B The electrical insulating material 72 may include strips of material wrapped around the outer surface 58 of the elongated, elastic distal segment 35.

[0088] In some exemplary embodiments, each electrode structure 48 includes a corresponding thermally conductive material 76 disposed below a respective primary electrode 68 and between the respective primary electrode 68 and the outer surface 58 of the distal segment 35. In some exemplary embodiments, the thermally conductive material 76 forms part of the primary electrode 68 (e.g., Figure 4C and Figure 4D (As shown). In other exemplary embodiments, the thermally conductive material 76 is placed as a separate element below the primary electrode 68 (e.g., a ring disposed around the outer surface 58), such as Figure 4A and Figure 4B As shown. In some exemplary embodiments, the thermally conductive material 76 is also used as the electrically insulating material 72, such as Figure 4B As shown.

[0089] Now for reference Figure 4A Now for reference. Figure 4A Typical dimensions of electrode structure 48 are described below. The dimensions described below can also be applied to other exemplary embodiments, for example, referencing... Figures 4B to 4D The exemplary implementation described herein. Although exemplary dimensions are described below, the dimensions of electrode structure 48 may include any suitable values.

[0090] The elongated, flexible distal segment 35 has an elongation direction 78. The primary electrode 68 has a width 80 measured parallel to the elongation direction 78. Each secondary electrode 70 has a width 82 measured parallel to the elongation direction 78. The width 80 is greater than the width 82. In some exemplary embodiments, the width 80 is at least twice the size of the width 82. In some exemplary embodiments, the width 80 is in the range of 2 mm to 8 mm, and the width 82 is in the range of 0.1 mm to 1 mm. Each electrode structure 48 has a total width 84 between 2.5 mm and 10 mm measured parallel to the elongation direction 79.

[0091] Figure 4A The thermally conductive material 76 is shown to be formed of a different material than the primary electrode 68. The thermally conductive material 76 may be formed as a rectangular strip wrapped around an elongated, resilient distal segment 35, with the primary electrode 68 wrapped on top of the thermally conductive material 76. In some exemplary embodiments, the thermally conductive material 76 and / or the primary electrode 68 may be formed as two semi-rings connected around the elongated, resilient distal segment 35. The secondary electrode 70 is connected to the primary electrode 68 via an electrically insulating material 72, which may also act as an adhesive to connect the primary electrode 68 to the secondary electrode 70. The wall thickness of the primary electrode 68 and the secondary electrode 70 may have any suitable value, for example, in the range of 0.01 mm to 0.25 mm. The thickness of the thermally conductive material 76 may have any suitable value, for example, in the range of 0.01 mm to 0.25 mm.

[0092] Now for reference Figure 4B . Figure 4B The electrically insulating material 72 and the thermally conductive material 76 are shown as the same element. The electrically insulating material 72 and the thermally conductive material 76 may be composed of epoxy resin such as boron nitride or diamond-doped epoxy resin, and have a thickness in the range of 0.01 mm to 0.25 mm. A primary electrode 68 is partially disposed on the electrically insulating material 72 and the thermally conductive material 76. A secondary electrode 70 is disposed on either side of the electrically insulating material 72 and the thermally conductive material 76. The dimensions of the primary electrode 68 and the secondary electrode 70 are consistent with reference to the reference. Figure 4A The dimensions mentioned are basically the same.

[0093] Now for reference Figure 4C and Figure 4D . Figure 4C and Figure 4DThe thermally conductive material 76 and the primary electrode 68 are shown as a single unit, whereby the thicker primary electrode 68 dissipates heat generated during electroporation. In some exemplary embodiments, the mass of the single unit may be greater than twice the mass of one of the secondary electrodes 70 of the electrode structure 48. The wall thickness of the primary electrode 68 may have any suitable value, for example, in the range of 0.025 mm to 0.5 mm. The wall thickness of the secondary electrode 70 may have any suitable value, for example, in the range of 0.025 mm to 0.5 mm. In some exemplary embodiments, the wall thickness of the primary electrode 68 is at least twice the wall thickness of the secondary electrode 70.

[0094] Figure 4C The primary electrode 68 and the secondary electrode 70 shown can each be formed as a flat electrode wound around the outer surface 58 to form a ring, or as two semi-rings connected together around the elongated elastic distal segment 35. Figure 4D The primary electrode 68 shown has a non-uniform surface and protrudes further away from the outer surface 58 towards the center of the primary electrode 68.

[0095] Now for reference Figure 5 The figure is a schematic diagram of an alternative sling catheter 86 constructed and operated according to an exemplary embodiment of the present invention. Referring now to... Figure 6 The image shows along Figure 5 Line B:B is a cross-sectional view of one of the electrode structures in the electrode structure 48 of the lasso conduit 86. Except for the following differences, the lasso conduit 86 is... Figure 1 The catheter 40 in Figure 4 is essentially the same. The slender, elastic distal segment 35 includes an internal irrigation lumen 94. Figure 6 Each electrode structure 48 (only some are labeled for simplicity) includes at least one flushing hole (perforation) 92 formed therethrough (only some are labeled for simplicity). Each electrode structure 48 defines a corresponding hollow segment 96 between the corresponding electrode structure and the outer surface 58. The perforation 92 is in fluid communication with the flushing chamber 94 via the hollow segment 96.

[0096] The lasso conduit 86 can be converted from a flushing conduit to a non-flushing conduit for performing electroporation, as described below. A thermally conductive material 90 is injected into a hollow segment 96 beneath each electrode structure 48 in the electrode structure 48 of the lasso conduit 86, located between the outer surface 58 of each electrode structure 48 and the distal segment 35. The placement of the thermally conductive material 90 generally prevents the lasso conduit 86 from providing flushing via the electrode structure 48. The thermally conductive material 90 can be injected beneath the electrode structure 48 via a perforation 92. The thermally conductive material 90 is typically formed of a material different from that of the electrode structure 48 (e.g., epoxy or platinum), but may also be formed of the same material as the electrode structure 48.

[0097] As used herein, the term “about” or “approximately” for any numerical value or range indicates a suitable dimensional tolerance that allows a collection of parts or components to achieve the intended purpose as described herein. More specifically, “about” or “approximately” may refer to a range of ±20% of the enumerated value, for example, “about 90%” may refer to a range of 72% to 108% of the value.

[0098] For clarity, the various features of the invention described in the context of individual embodiments may also be provided in combination in a single embodiment. Conversely, for brevity, the various features of the invention described in the context of individual embodiments may also be provided individually or in any suitable sub-combination.

[0099] The above embodiments are cited by way of example, and the invention is not limited to the specific details shown and described above. Rather, the scope of the invention includes combinations and sub-combinations of the various features described above, as well as variations and modifications thereof, which should be apparent to those skilled in the art upon reading the above description, and which are not disclosed in the prior art.

Claims

1. A medical system comprising a catheter, said catheter comprising: An insertion tube having a distal end; An elongated, flexible distal segment is fixed to the distal end of the insertion tube, the elongated, flexible distal segment having an outer surface; and Multiple electrode structures are provided, each electrode structure being disposed around and protruding from the outer surface of the elongated elastic distal segment. Each electrode structure includes a corresponding primary electrode and at least one corresponding secondary electrode, the corresponding secondary electrode being rigidly connected to the corresponding primary electrode. An electrically insulating material is located between the corresponding primary electrode and the at least one corresponding secondary electrode. The degree to which the corresponding primary electrode protrudes from the outer surface is greater than that of the at least one corresponding secondary electrode and the corresponding electrically insulating material. The at least one corresponding secondary electrode includes an outer annular surface, an inner annular surface, and two side surfaces, and the electrically insulating material is disposed on one of the two side surfaces and extends to the corresponding primary electrode to cover the one of the two side surfaces and fill the volume between the one of the two side surfaces and the corresponding primary electrode.

2. The system of claim 1, wherein the insertion tube is configured for insertion through a blood vessel into the heart of a subject, and wherein, when the elongated flexible distal segment is deployed within the heart, the elongated flexible distal segment defines a collar and is configured to open and close the collar.

3. The system according to claim 2, wherein the diameter of the collar is between 5 mm and 35 mm.

4. The system of claim 1, wherein the respective primary electrode comprises a metal ring, and the at least one respective secondary electrode comprises at least one metal ring, the respective primary electrode and the at least one respective secondary electrode being connected by the respective electrical insulating material.

5. The system of claim 1, wherein the at least one corresponding secondary electrode comprises two corresponding electrodes.

6. The system of claim 5, wherein the two corresponding electrodes are disposed on either side of the corresponding primary electrode.

7. The system of claim 5, wherein the elongated elastic distal segment has an elongation direction, the corresponding primary electrode has a first width measured parallel to the elongation direction, each of the two corresponding electrodes has a second width measured parallel to the elongation direction, the first width being greater than the second width.

8. The system of claim 7, wherein the first width is at least twice the size of the second width.

9. The system of claim 7, wherein the first width is in the range of 2 mm to 8 mm, and the second width is in the range of 0.1 mm to 1 mm.

10. The system of claim 1, wherein the elongated elastic distal segment has an elongation direction, and each electrode structure has a width between 2.5 mm and 10 mm measured parallel to the elongation direction.

11. The system of claim 1, wherein each electrode structure includes a corresponding thermally conductive material disposed below the respective primary electrode and between the outer surface of the respective primary electrode and the elongated elastic distal segment.

12. The system of claim 11, wherein the corresponding thermally conductive material is formed of a material different from that of the corresponding primary electrode.

13. The system of claim 11, wherein the respective thermally conductive material and the respective primary electrode are formed as a single unit, the mass of the single unit being greater than twice the mass of the at least one respective secondary electrode.

14. The system of claim 1 further includes a signal generator configured to generate a pulse signal that will be applied by the respective primary electrode to cardiac tissue to perform electroporation of the cardiac tissue.

15. The system of claim 14, further comprising an intracardiac electrogramming (IEGM) module configured to receive at least one signal sensed by the at least one corresponding secondary electrode and generate an intracardiac electrogram for output to a display device.

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