Proximal electrode cooling

Abstract

To provide a medical system.SOLUTION: In one embodiment, a medical system includes a catheter configured to be inserted into a body part of a living subject. The catheter includes: a deflectable element having a distal end; an expandable distal end assembly disposed at the distal end of the deflectable element, the expandable distal end assembly including a plurality of electrodes and configured to expand from a collapsed form to an expanded deployed form; a proximal electrode disposed at the distal end of the deflectable element proximally to the expandable distal end assembly, the proximal electrode extending circumferentially around the deflectable element and including irrigation holes through which the body part is irrigated; and an irrigation tube disposed in the deflectable element and configured to be in fluid communication with the irrigation holes of the proximal electrode.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to medical devices, particularly but not exclusively to ablation catheters. [Background technology]

[0002] A wide range of medical procedures involve the placement of probes, such as catheters, within a patient's body. Position sensing systems have been developed to track such probes. Magnetic position sensing is one method known in the art. In magnetic position sensing, magnetic field generators are typically placed at known locations 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, and 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. Patent Nos. 5,391,199, 6,690,963, 6,484,118, 6,239,724, 6,618,612, and 6,332,089, WO 1996 / 005768, and U.S. Patent Application Publication Nos. 2002 / 006455, 2003 / 0120150, and 2004 / 0068178. Position may also be tracked using impedance or current-based systems.

[0003] One medical procedure in which these types of probes or catheters have proven extremely useful is in the treatment of cardiac arrhythmias, which, and atrial fibrillation in particular, remain common and dangerous conditions, especially in the aging population.

[0004] Diagnosis and treatment of cardiac arrhythmias involve mapping the electrical properties of cardiac tissue, particularly the endocardium, and selectively ablating the cardiac tissue through the application of energy. Such ablation can stop or modify the propagation of unwanted electrical signals from one part of the heart to another. The ablation process disrupts unwanted electrical pathways by creating non-conductive lesions. Various energy delivery modalities have been previously disclosed for creating lesions, including the use of microwave, laser, and more commonly, radiofrequency energy to create conduction blocks along cardiac tissue walls. In a two-step mapping-then-ablation procedure, a catheter containing one or more electrical sensors is typically advanced into the heart to detect and measure electrical activity at each point within the heart by acquiring data at multiple points. These data are then used to select a target region of the endocardium for this ablation.

[0005] Electrode catheters have been commonly used in medical practice for many years. They are used to stimulate and map electrical activity within the heart and to ablate sites of abnormal electrical activity. In use, an electrode catheter is inserted into a major vein or artery, such as the femoral vein, and then guided into the cardiac chamber of interest. A typical ablation procedure involves inserting a catheter with one or more electrodes at its distal end into a cardiac chamber. A reference electrode is typically taped to the patient's skin or may be provided by a second catheter placed in or near the heart. Radio frequency (RF) current is applied through the tip electrode(s) of the ablation catheter, and current flows through the medium surrounding the tip electrode(s), i.e., blood and tissue, between the tip electrode(s) and an indifferent electrode. The distribution of the current depends on the amount of electrode surface in contact with the tissue compared to blood, which has a higher electrical conductivity than tissue. Tissue heating occurs due to the electrical resistance of the tissue. Sufficient tissue heating can cause cell destruction in the cardiac tissue, resulting in lesions in the non-conductive cardiac tissue.

[0006] Irreversible electroporation (IRE) applies a short electrical pulse that generates a sufficiently high electric field (typically greater than 450 volts per centimeter) to irreversibly damage cells. Non-thermal IRE may be used to treat different types of tumors and other unwanted tissues without causing thermal damage to surrounding tissues. A small electrode is placed in close proximity to the target tissue and a short electrical pulse is applied. The pulse increases the resting transmembrane potential, and nanopores form in the plasma membrane. When the electricity applied to the tissue exceeds the electric field threshold of the target tissue, the cells become permanently permeable from the formation of the nanopores. As a result, the cells are unable to repair the damage due to a lack of homeostasis and die, typically by apoptosis.

[0007] IRE may be used for cardiac ablation as an alternative to other cardiac ablation techniques, such as radiofrequency (RF) cardiac ablation. IRE cardiac ablation is sometimes referred to as pulsed-field ablation (PFA). Because IRE is generally a low-thermal technique, IRE may reduce the risk of collateral damage that is present with other techniques, such as RF cardiac ablation.

[0008] U.S. Patent No. 9,011,430 to Habib describes a device and method suitable for remodeling the interior surface of a hollow blood vessel that is at least partially occluded by a mass. The device includes an elongate body having a distal end and a proximal end, the distal end including a tip portion located at the distal end of the body and at least one heating element located within the distal end proximal to the tip portion. The at least one heating element is configured to be larger in size proximally than distally, thereby tapering toward the distal end. Furthermore, the at least one heating element is positioned to be deployable outward from the body of the device, thereby applying an expansive force to the hollow blood vessel.

[0009] U.S. Patent Application Publication No. 2020 / 0038103 to Pappone et al. describes a fluid delivery balloon ablation catheter configured to enable uniform fluid distribution through each electrode by varying the diameter of the main lumen. The catheter includes an elongated tubular catheter body having a distal end, a proximal end, and a lumen extending longitudinally within the catheter body. Numerous elution holes are provided in the catheter tip section, and these holes are in fluid communication with the lumen through a duct. Thus, cooling fluid is delivered from a pump, passes through the duct, passes through the lumen, and exits through the holes to the environment outside the catheter. The main lumen has at least one tapered fluid constriction to restrict fluid flow toward the distal region of the lumen. The catheter has multiple semi-dome-shaped balloons, with the distal balloon being the smallest and the proximal balloon being the largest.

[0010] U.S. Patent Application Publication No. 2020 / 179045 to Engelman et al. describes devices and methods for treating heart failure patients by ablating nerves of the splanchnic sympathetic nervous system, increasing venous capacity, and reducing pulmonary blood pressure.

[0011] U.S. Patent No. 10,524,859 to Vrba et al. describes systems, devices, and methods for modulating targeted nerve fibers (e.g., hepatic neuromodulation) or other tissues. Systems, devices, and methods for cooling energy delivery members are also provided. The system can be configured to access the tortuous anatomical structure of the adjacent hepatic vasculature. The system can be configured to target nerves (e.g., within the adventitia or perivascular space) surrounding arteries or other blood vessels, such as the common hepatic artery.

[0012] U.S. Patent Application Publication No. 2016 / 0074112 to Himmelstein describes an ablation device for denervation that includes a catheter delivery mechanism including an elongated tube having a distal end and a proximal end, the distal end of which is insertable into a body cavity in a target nerve region. A guidewire, at least one radiofrequency electrode, multiple positioning elements, and multiple pushing elements are initially positioned within the tube. The electrodes are deployable from the tube in the target nerve region to form an annular structure adjacent the distal tube end. The positioning elements are deployable in the target nerve region from a position in the tube more distal to the electrodes. The pushing elements are deployable from a position in the tube proximal to the electrodes for use in pressing the deployed electrodes against tissue to be ablated.

[0013] WO 2015200518 to Apama Medical Inc. describes tissue ablation devices, systems, and methods for monitoring or analyzing one or more aspects of tissue ablation. The disclosure includes an ablation catheter having an elongate shaft, an inflatable balloon carried by a distal region of the shaft, a flexible circuit including conductors in electrical communication with ablation electrodes, the flexible circuit being disposed outside of and carried by an outer surface of the inflatable balloon, and an ultrasound monitoring member configured for use in monitoring at least one aspect of tissue ablation by the ablation electrodes. Summary of the Invention [Means for solving the problem]

[0014] According to an embodiment of the present disclosure, there is provided a medical system comprising a catheter configured to be inserted into a body part of a living subject, the catheter comprising: a deflectable element having a distal end; an expandable distal end assembly disposed at the distal end of the deflectable element, the expandable distal end assembly including a plurality of electrodes and configured to expand from a collapsed configuration to an expanded, deployed configuration; a proximal electrode disposed at the distal end of the deflectable element proximal to the expandable distal end assembly, the proximal electrode extending circumferentially around the deflectable element and including irrigation holes for irrigating the body part; and an irrigation tube disposed within the deflectable element and configured to be in fluid communication with the irrigation holes of the proximal electrode.

[0015] Further, according to an embodiment of the present disclosure, the expandable distal end assembly includes at least one of an expandable basket including a plurality of splines with electrodes disposed on the splines, or an inflatable balloon with electrodes disposed thereon.

[0016] Still further, in accordance with an embodiment of the present disclosure, irrigation holes are disposed radially around the proximal electrode.

[0017] Additionally, in accordance with an embodiment of the present disclosure, irrigation holes are disposed longitudinally along the proximal electrode.

[0018] Furthermore, in accordance with an embodiment of the present disclosure, irrigation holes are disposed longitudinally along the proximal electrode.

[0019] Further, according to an embodiment of the present disclosure, the proximal electrode and the deflectable element define an annular hollow therebetween, and the irrigation tube is coupled to transport irrigation fluid within the hollow, the irrigation tube being in fluid communication with the irrigation hole through the hollow.

[0020] Still further, according to an embodiment of the present disclosure, the system includes an ablation power generator connected to the catheter and configured to apply an electrical signal between at least one of the electrodes and the proximal electrode; an irrigation reservoir configured to store irrigation fluid; and a pump connected to the irrigation reservoir and the catheter and configured to pump the irrigation fluid from the irrigation reservoir through the irrigation hole via the irrigation tube.

[0021] Additionally, according to embodiments of the present disclosure, the ablation power generator is configured to apply an electrical signal between at least one of the electrodes and the proximal electrode to electroporate tissue of the body part.

[0022] Further, according to an embodiment of the present disclosure, the proximal electrode and the deflectable element define an annular hollow therebetween, the irrigation tube is connected to transport irrigation fluid within the hollow, the irrigation tube is in fluid communication with the irrigation hole through the hollow, and the pump is configured to pump irrigation fluid from the irrigation reservoir through the irrigation tube into the hollow and out of the irrigation hole.

[0023] Furthermore, according to an embodiment of the present disclosure, the system includes another irrigation tube disposed within the deflectable element and configured to deliver irrigation fluid within the area surrounded by the expandable distal end assembly.

[0024] Still further, according to an embodiment of the present disclosure, the electrodes of the expandable distal end assembly include irrigation holes in fluid communication with separate irrigation tubing.

[0025] Also provided according to another embodiment of the present disclosure is a medical system comprising a catheter configured to be inserted into a body portion of a living subject, the catheter comprising: a deflectable element having a distal end and an axis; an expandable distal end assembly disposed at the distal end of the deflectable element, the expandable distal end assembly including a plurality of electrodes and configured to expand from a collapsed configuration to an expanded, deployed configuration; and a proximal electrode disposed at the distal end of the deflectable element proximal to the expandable distal end assembly, the proximal electrode extending circumferentially around the deflectable element, the proximal electrode having a maximum thickness measured perpendicular to the axis of the deflectable element of at least 0.20 mm and an inner diameter in the range of 2 mm to 6 mm.

[0026] Additionally, according to embodiments of the present disclosure, the expandable distal end assembly includes at least one of an expandable basket including a plurality of splines with electrodes disposed on the splines, or an inflatable balloon with electrodes disposed thereon.

[0027] Further, according to an embodiment of the present disclosure, the system includes an ablation power generator connected to the catheter and configured to apply an electrical signal between at least one of the electrodes and the proximal electrode.

[0028] Further, according to an embodiment of the present disclosure, the ablation power generator is configured to apply an electrical signal between at least one of the electrodes and the proximal electrode to electroporate tissue of the body part.

[0029] Still further, according to an embodiment of the present disclosure, the system includes an irrigation tube disposed within the deflectable element and configured to deliver irrigation fluid within an area surrounded by the expandable distal end assembly.

[0030] Additionally, according to an embodiment of the present disclosure, the electrodes of the expandable distal end assembly include irrigation holes in fluid communication with the irrigation tubing.

[0031] Also provided in accordance with yet another embodiment of the present disclosure is a medical system comprising a catheter configured to be inserted into a body portion of a living subject, the catheter comprising: a deflectable element having a distal end; an expandable distal end assembly disposed at the distal end of the deflectable element, the expandable distal end assembly including a plurality of electrodes and configured to expand from a collapsed configuration to an expanded, deployed configuration; a proximal electrode disposed at the distal end of the deflectable element proximal to the expandable distal end assembly, the proximal electrode extending circumferentially around the deflectable element, the proximal electrode and the deflectable element defining an annular region therebetween; and a thermally conductive material disposed within the annular region, the thermally conductive material being formed of a material different from the proximal electrode.

[0032] Further, according to an embodiment of the present disclosure, the expandable distal end assembly includes at least one of an expandable basket including a plurality of splines with electrodes disposed on the splines, or an inflatable balloon with electrodes disposed thereon.

[0033] Further, according to an embodiment of the present disclosure, the system includes an ablation power generator connected to the catheter and configured to apply an electrical signal between at least one of the electrodes and the proximal electrode.

[0034] Still further, according to an embodiment of the present disclosure, the ablation power generator is configured to apply an electrical signal between at least one of the electrodes and the proximal electrode to electroporate tissue of the body part.

[0035] Additionally, according to an embodiment of the present disclosure, the system includes an irrigation tube disposed within the deflectable element and configured to deliver irrigation fluid within an area surrounded by the expandable distal end assembly.

[0036] Furthermore, according to an embodiment of the present disclosure, the electrodes of the expandable distal end assembly include irrigation holes in fluid communication with the irrigation tubing. [Brief explanation of the drawings]

[0037] The present invention will be understood from the following detailed description taken in conjunction with the accompanying drawings. [Figure 1] 1 is a schematic diagram of a medical system constructed and operative in accordance with an embodiment of the present invention. [Figure 2] 1 is a schematic illustration of a catheter in a deployed configuration, constructed and operative in accordance with an embodiment of the present invention; [Figure 3] FIG. 3 is a schematic diagram of the distal end of the catheter of FIG. 2 in a collapsed configuration. [Figure 4A] FIG. 3 is a cross-sectional view of the distal end of the catheter of FIG. 2. [Figure 4B] FIG. 4B is a more detailed cross-sectional view of the distal end of the catheter inside block B of FIG. 4A. [Figure 5A] FIG. 3 is a cross-sectional view of the catheter of FIG. 2 taken along line A:A. [Figure 5B] 3 is a cross-sectional view of the catheter of FIG. 2 taken along line B:B. [Figure 6] FIG. 1 is a schematic illustration of a catheter in a deployed configuration constructed and operative in accordance with an alternative embodiment of the present invention. [Figure 7] FIG. 7 is a cross-sectional view of the catheter of FIG. 6 taken along line C:C. [Figure 8] FIG. 7 is a cross-sectional view of the catheter of FIG. 6 taken along line C:C, constructed and operative in accordance with another alternative embodiment of the present invention. [Figure 9] FIG. 1 is a schematic illustration of a catheter in a deployed configuration constructed and operative in accordance with yet another alternative embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0038] Overview A balloon catheter or another catheter having an expandable distal tip assembly, such as a basket catheter, may include electrodes on the distal tip assembly that can be used for ablation. The catheter is inserted into a body part (e.g., a heart chamber) of a living subject, and an ablation current is applied between the catheter electrodes to ablate tissue in the body part.

[0039] A return electrode may be used such that the ablation current is applied between one or more of the distal tip assembly electrodes and the return electrode. If the ablation current is applied between electrodes on the distal tip assembly or between one or more electrodes of the distal tip assembly and a return electrode located in the center of the distal tip assembly, the ablation current may be prevented from traveling through tissue, thereby reducing the efficiency of the ablation current. Locating the return electrode proximal to the expandable distal tip assembly helps prevent the ablation current from traveling inside the distal tip assembly. However, the concentration of ablation energy at the proximal return electrode may cause the proximal return electrode to overheat or char tissue.

[0040] Embodiments of the present invention solve the above problems by providing an irrigated proximal electrode positioned at the distal end of a deflectable element of a catheter, proximal to an expandable distal tip assembly, such as a balloon or basket assembly, that includes an electrode. The proximal electrode extends circumferentially around the deflectable element and includes irrigation holes for irrigating the body part to prevent overheating and charring.

[0041] An irrigation tube disposed within the deflectable element is in fluid communication with irrigation holes in the proximal electrode, which are generally disposed around and longitudinally along the periphery of the proximal electrode.

[0042] In some embodiments, the proximal electrode and the deflectable element define an annular hollow therebetween, the irrigation tube is coupled to carry irrigation fluid into the hollow, such that the irrigation tube is in fluid communication with the irrigation hole through the hollow, and the pump pumps irrigation fluid from the irrigation reservoir, through the irrigation tube, into the hollow and out of the irrigation hole.

[0043] In some embodiments, an ablation power generator is connected to the catheter and applies an electrical signal between at least one of the electrodes and the proximal electrode to perform radio frequency (RF) ablation or electroporation of tissue in the body part.

[0044] In some embodiments, the expandable distal end assembly is also irrigated. A second irrigation tube is disposed within the deflectable element and can deliver irrigation fluid to the area encompassed by the expandable distal end assembly. In some embodiments, the electrodes of the expandable distal end assembly (e.g., balloon assembly) include irrigation holes in fluid communication with the second irrigation tube. In some embodiments, the irrigation of the expandable distal end assembly and the proximal electrode share the same irrigation tube.

[0045] In other embodiments, the proximal electrode is not irrigated. The distal end of the deflectable element and the proximal electrode define an annular region therebetween. A thermally conductive material is disposed within the annular region to dissipate heat from the tissue surrounding the proximal electrode, thereby preventing or reducing overheating and charring. The thermally conductive material may be formed from a different material than the proximal electrode.

[0046] In other embodiments, the proximal electrode is formed from a thick piece of thermally conductive material to dissipate heat from the tissue surrounding the proximal electrode, thereby preventing or reducing overheating and charring. In some embodiments, the proximal electrode has a maximum thickness, measured perpendicular to the axis of the deflectable element, of at least 0.20 mm and an inner diameter in the range of 2 mm to 6 mm.

[0047] System Description Reference is now made to FIG. 1, which is a schematic illustration of a medical system 20 constructed and operative in accordance with an embodiment of the present invention. System 20 includes a catheter 40 configured to be inserted into a body portion of a living subject (e.g., patient 28). A physician 30 navigates catheter 40 (e.g., a basket catheter manufactured by Biosense Webster, Irvine, California, USA) to a target location in heart 26 of patient 28 by manipulating elongated, deflectable element 22 of catheter 40 using a manipulator 32 near the proximal end of catheter 40 and / or deflection from a sheath 23. In the illustrated embodiment, physician 30 uses catheter 40 to perform electroanatomical mapping of heart cavities and ablation of cardiac tissue.

[0048] The catheter 40 includes an expandable distal tip assembly 35 (e.g., a basket assembly) that is inserted through the sheath 23 in a collapsed configuration, and only after the catheter 40 exits the sheath 23 does the distal tip assembly 35 resume its intended functional shape. By housing the distal tip assembly 35 in a collapsed configuration, the sheath 23 also serves to minimize vascular trauma en route to the target location.

[0049] The catheter 40 includes a plurality of electrodes 48 disposed on the expandable distal tip assembly 35 for sensing electrical activity and / or applying ablation power to ablate tissue in the body portion. The catheter 40 also includes a proximal electrode 21 disposed on the deflectable element 22 proximal to the expandable distal tip assembly 35. The catheter 40 may incorporate a magnetic position sensor (not shown) at the distal edge of the deflectable element 22 (i.e., the proximal edge of the distal tip assembly 35). Typically, but not necessarily, the magnetic sensor is a single-axis sensor (SAS). A second magnetic sensor (not shown) may be included in any suitable location on the assembly 35. The second magnetic sensor may be, by way of example, a triaxial sensor (TAS) or a dual-axis sensor (DAS), or an SAS, depending, for example, on size considerations. The magnetic sensor, proximal electrode 21, and electrodes 48 disposed on the assembly 35 are connected to various drive circuits within the console 24 by wires extending through the deflectable element 22.

[0050] In some embodiments, system 20 includes a magnetic sensing subsystem that estimates the ellipticity of basket assembly 35 of catheter 40 and its extension / retraction state within a cardiac cavity of heart 26 by estimating the extension of basket assembly 35 from the distance between magnetic sensors. Patient 28 is placed in a magnetic field generated by a pad including one or more magnetic field generator coils 42 driven by unit 43. The magnetic field generated by coil(s) 42 transmits an alternating magnetic field into the area where the body part is located. The transmitted alternating magnetic field generates signals in the magnetic sensors that indicate position and / or orientation. The generated signals are transmitted to console 24 and become corresponding electrical inputs to processing circuitry 41.

[0051] Position and / or orientation sensing methods using external magnetic fields and magnetic sensors have been implemented in various medical applications, for example, in the CARTO® system manufactured by Biosense-Webster, and are described in detail in U.S. Pat. Nos. 5,391,199, 6,690,963, 6,484,118, 6,239,724, 6,618,612, and 6,332,089, WO 96 / 05768, and U.S. Patent Application Publication Nos. 2002 / 0065455(A1), 2003 / 0120150(A1), and 2004 / 0068178(A1).

[0052] Processing circuitry 41, which is typically part of a general-purpose computer, is further connected through 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 by wires that extend through cable 39 to the chest of patient 28.

[0053] In one embodiment, processing circuitry 41 renders a representation 31 of at least a portion of catheter 40 and the mapped body part on display 27 in response to the calculated position coordinates of catheter 40 .

[0054] Processing circuitry 41 is typically programmed with software to carry out the functions described herein, which software may be downloaded to a computer in electronic form, for example over a network, or alternatively or additionally may be provided and / or stored on a non-transitory tangible medium, such as magnetic, optical, or electronic memory.

[0055] The medical system 20 may also include an ablation power generator 69 (such as an RF signal generator) connected to the catheter 40 and configured to apply an electrical signal between one or more of the electrodes 48 and the proximal electrode 21. The medical system 20 may also include an irrigation reservoir 71 configured to store irrigation fluid, and a pump 73 configured to connect to the irrigation reservoir 71 and the catheter 40 and configured to pump irrigation fluid from the irrigation reservoir 71, through the irrigation tubing, and through the irrigation lumen of the catheter 40, as will be described in more detail with reference to Figures 5A and 5B.

[0056] The illustration shown in Figure 1 has been selected solely for conceptual clarity. For simplicity and clarity, Figure 1 shows only elements relevant to the disclosed techniques. System 20 typically includes additional modules and elements not directly relevant to the disclosed technology and therefore intentionally omitted from Figure 1 and the corresponding description. Elements of system 20 and methods described herein may be further applied, for example, to control the ablation of tissue in heart 26.

[0057] Reference is now made to Figures 2 and 3. Figure 2 is a schematic illustration of a catheter 40 constructed and operative in accordance with an embodiment of the present invention in a deployed configuration. Figure 3 is a schematic illustration of the distal end of catheter 40 of Figure 2 in a collapsed configuration.

[0058] In FIG. 2 , catheter 40 extends along longitudinal axis LL from a proximal location (closest to the operator) to a distal location along axis LL farthest from the operator. For example, portion 35 may be considered a “distal” portion with respect to portion 33, while portion 33 may be considered a “proximal” portion. Catheter 40 is configured to be inserted into a body portion of a living subject (e.g., heart 26 ( FIG. 1 )). Deflectable element 22 of catheter 40 has a distal end 33. Deflectable element 22 may be manufactured from any suitable material, for example, polyurethane or polyether block amide. Assembly 35 may be disposed distal to deflectable element 22 and connected to deflectable element 22 at distal end 33 via proximal linkage member 50. The proximal linking member 50 typically comprises a hollow tube and may be formed from any suitable material, such as, but not limited to, polycarbonate with or without glass fillers, polyetheretherketone (PEEK) with or without glass fillers, polyimide, polyamide, or polyetherimide (PEI) with or without glass fillers. The linking member 50 may be formed as an integral part of the deflectable element 22, as part of the distal end assembly 35, or as a separate element that connects the deflectable element 22 and the distal end assembly 35.

[0059] Assembly 35, which may include a basket assembly, may include multiple splines, such as flexible strips 55 (only one labeled for simplicity), with electrodes 48 disposed on the splines. In the embodiment of Figures 2 and 3, each flexible strip 55 includes a single electrode 48 (only some labeled for simplicity). Assembly 35 may include any suitable number of electrodes 48, with multiple electrodes 48 per strip 55.

[0060] In the embodiment of FIGS. 2 and 3 , each flexible strip 55 is formed of nitinol and selectively coated with an insulating material (e.g., a thermoplastic polymer shrink wrap (PET)) within distal and proximal regions 57 of the flexible strip 55 (only some of which are labeled for simplicity), leaving a central region 59 of the flexible strip 55 (only some of which are labeled for simplicity) as an electroactive region to perform mapping and / or ablation or electroporation, for example. The structure of the assembly 35 can vary. For example, the flexible strips 55 (or other splines) can include a flexible printed circuit board (PCB) or a shape memory alloy such as nitinol. The electroactive region of each flexible strip 55 can be larger or smaller than that shown in FIG. 2 and / or can be disposed more centrally or proximally on each flexible strip 55.

[0061] The embodiments described herein, by way of example only, refer primarily to a basket distal end assembly 35. In alternative embodiments, the disclosed techniques may be used with any other suitable type of distal end assembly.

[0062] The distal tip assembly 35 includes a distal portion 61 and a proximal portion 63 and is configured to expand from a collapsed configuration (shown in FIG. 3 ) to an expanded, deployed configuration (shown in FIG. 2 ). The relaxed state of the distal tip assembly 35 is the expanded, deployed configuration shown in FIG. 2 . The distal tip assembly 35 is configured to collapse to the collapsed configuration when the catheter 40 is stored within the sheath 23 ( FIG. 1 ) and to expand to the expanded, deployed configuration when the catheter 40 is removed from the sheath 23. The relaxed shape of the distal tip assembly 35 can be set by forming the flexible strip 55 from any suitable elastic material, such as nitinol or PEI. In some embodiments, the relaxed state of the expandable distal tip assembly 35 can be the collapsed configuration, and the expandable distal tip assembly 35 is expanded using a pull wire or element connected to the distal portion 61 and fed through a lumen in the deflectable element 22.

[0063] The proximal electrode 21 is disposed proximal to the expandable distal tip assembly 35 at the distal end 33 of the deflectable element 22 and extends generally circumferentially around the deflectable element 22. The proximal electrode 21 includes irrigation holes 65 (only some of which are labeled for simplicity) for irrigating a body part. The irrigation holes 65 are generally disposed around the periphery of the proximal electrode 21 and / or longitudinally along the proximal electrode 21. The irrigation holes may have any suitable diameter, for example, within the range of 25 to 100 micrometers. The holes may be formed using any suitable technique, for example, laser drilling or electrical discharge machining (EDM). The proximal electrode 21 may include any suitable number of holes, for example, within the range of 4 to 100. In one example, the proximal electrode 21 includes five proximally disposed holes and five distally disposed holes.

[0064] An ablation power generator 69 (FIG. 1) is connected to the catheter 40 and configured to apply an electrical signal between at least one of the electrodes 48 and the proximal electrode 21. In some embodiments, the ablation power generator 69 is configured to apply an electrical signal between at least one of the electrodes 48 and the proximal electrode 21 to electroporate tissue of the body part.

[0065] Reference is now made to Figures 4A and 4B. Figure 4A is a cross-sectional view of the distal end of catheter 40 of Figure 2. Figure 4B is a more detailed cross-sectional view of the distal end of catheter 40 inside block B of Figure 4A.

[0066] The distal ends of the flexible strips 55 (only two are labeled for simplicity) are folded over and connected to a distal connector 75, which in some embodiments is a tube (e.g., a polymer tube) or a slug (e.g., a polymer slug). The distal connector 75 may be formed from any suitable material, such as, but not limited to, polycarbonate with or without glass fillers, PEEK with or without glass fillers, or PEI with or without glass fillers. In some embodiments, the flexible strips 55 may be connected to the distal connector 75 without being folded, such that the flexible strips 55 approximate a flat formation along their lengths when the distal tip assembly 35 is collapsed. The proximal ends of the flexible strips 55 are connected to the proximal connecting member 50. The flexible strips 55 may be connected to the distal connector 75 and the proximal connecting member 50 using a suitable adhesive, such as an epoxy adhesive.

[0067] In some embodiments, the catheter 40 includes a nose cap 77 inserted into the distal connector 75. The nose cap 77 may be used to help secure the flexible strip 55 to the distal connector 75. The nose cap 77 may be formed from any suitable material, such as, but not limited to, polycarbonate with or without glass fillers, PEEK with or without glass fillers, or PEI with or without glass fillers. The nose cap 77 may optionally be sized to provide a press fit against the flexible strip 55 to prevent the flexible strip 55 from pulling away from the inner surface of the distal connector 75.

[0068] In some embodiments, the thickness of the distal portion of the flexible strip 55 can be reduced (relative to the remainder of the flexible strip 55) to provide hinges 79 (one hinge 79 per flexible strip 55) that allow the flexible strip 55 to flex sufficiently between the collapsed and deployed configurations of the expandable distal end assembly 35. For simplicity, only two of the hinges 79 are labeled. The hinges 79 of the flexible strips 55 may be reinforced using a flexible material, such as thread (not shown). The hinges 79 (including the thread and covering layer) may have any suitable thickness, for example, in the range of 10 to 140 micrometers. The thread 52 may include any one or more of ultra-high molecular weight polyethylene thread or thread spun from a liquid crystal polymer. The thread may be of any suitable linear density, for example, in the range of 25 denier to 250 denier.

[0069] Reference is now made to Figures 5A and 5B. Figure 5A is a cross-sectional view of catheter 40 of Figure 2 taken along line A:A. Figure 5B is a cross-sectional view of the catheter of Figure 2 taken along line B:B.

[0070] 5A and 5B show the proximal electrode 21 extending circumferentially around the deflectable element 22. The edges of the proximal electrode 21 may be connected to the deflectable element 22 using a suitable adhesive and / or using a covering such as a thermoplastic polymer shrink wrap. FIGS. 5A and 5B show some of the irrigation holes 65 in the proximal electrode 21 (only some are labeled for simplicity). The proximal electrode 21 may have any suitable width measured parallel to the direction of elongation of the deflectable element 22, for example, in the range of 2 to 10 mm.

[0071] Catheter 40 includes irrigation tubing 81 disposed within deflectable element 22 and configured to be in fluid communication with irrigation holes 65 of proximal electrode 21. Pump 73 (FIG. 1) is connected to irrigation reservoir 71 (FIG. 1) and catheter 40 and configured to pump irrigation fluid from irrigation reservoir 71, through irrigation holes 65, and via irrigation tubing 81.

[0072] The inner surface of the proximal electrode 21 and the deflectable element 22 define an annular hollow 83 therebetween. An irrigation tube 81 is coupled to the annular hollow 83 to transport irrigation fluid within the hollow 83. The irrigation tube 81 is generally disposed in the irrigation hole 65 on the other side of the annular hollow 83. Thus, the irrigation tube 81 is in fluid communication with the irrigation hole 65 through the hollow 83. The pump 73 (FIG. 1) is configured to pump irrigation fluid from the irrigation reservoir 71, through the irrigation tube 81, into the hollow 83, and out of the irrigation hole 65. The collection of irrigation fluid within the annular hollow 83 acts to cool the outer surface of the proximal electrode 21, rather than just the portion proximate the irrigation hole 65.

[0073] Catheter 40 may include another irrigation tube 85 disposed within deflectable element 22 and configured to deliver irrigation fluid to an area 87 (FIG. 2) surrounded by flexible strip 55 of expandable distal tip assembly 35. Irrigation tube 85 typically extends within expandable distal tip assembly 35 as shown in FIGS. 2 and 3.

[0074] In some embodiments, catheter 40 includes a position sensor 89 (such as a magnetic position sensor) disposed within deflectable element 22. Figures 5A and 5B also show wires 91 disposed internally connecting electrode 48, proximal electrode 21, and position sensor 89 with the proximal end of catheter 40.

[0075] Reference is now made to Figure 6, which is a schematic illustration of a catheter 100 in a deployed configuration, constructed and operative in accordance with an alternative embodiment of the present invention. Catheter 100 is substantially similar to catheter 40 of Figures 2 and 3, except for the following differences: Catheter 100 includes a proximal electrode 106 that is not irrigated. Proximal electrode 106 may be cooled by filling it with a thermally conductive material, as described with reference to proximal electrode 106-1 of Figure 7, or by forming the proximal electrode from a thermally conductive material of sufficient thickness to dissipate heat, as described with reference to proximal electrode 106-2 of Figure 8.

[0076] Reference is now made to Figure 7, which is a cross-sectional view of the catheter 100 of Figure 6 taken along line C:C. The proximal electrode 106-1 and the distal end of the deflectable element 22 define an annular region 102 therebetween. The catheter 100 includes a thermally conductive material 104 disposed within the annular region 102, typically, but not necessarily, filling the annular region 102 and typically in contact with at least a portion of the inner surface of the proximal electrode 106-1. The thermally conductive material 104 may be formed from a different material than the proximal electrode 106-1.

[0077] As used herein and in the claims, the term "thermally conductive material" is defined as a material having a thermal conductivity of 1 Watt per meter Kelvin (W / mK) or greater at 25 degrees Celsius. The thermally conductive material 104 may be any suitable thermally conductive material, such as, but not limited to, platinum, palladium, gold, or a thermally conductive epoxy. In some embodiments, the thermally conductive material 104 is first wrapped around the outer surface of the deflectable element 22, and then the proximal electrode 106-1 is wrapped around the thermally conductive material 104. In other embodiments, the proximal electrode 106-1 (either as a single piece or as two halves that are later joined together) is first secured around the deflectable element 22, and then the thermally conductive material 104 is injected under the proximal electrode 106-1 through a hole (not shown) in the proximal electrode 106-1.

[0078] The wall thickness "t" of the proximal electrode 106-1 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 104 may have any suitable value, for example, in the range of 0.01 mm to 0.25 mm. The proximal electrode 106-1 may have any suitable width measured parallel to the direction of elongation of the deflectable element 22, for example, from 2 to 10 mm.

[0079] Note that irrigation tubing 81 (FIGS. 5A and 5B) is not included within the deflectable element 22 shown in FIG.

[0080] Reference is now made to Fig. 8, which is a cross-sectional view of catheter 100 of Fig. 6 taken along line C:C, constructed and operative in accordance with another alternative embodiment of the present invention. Proximal electrode 106-2 shown in Fig. 8 has a wall thickness greater than the wall thickness "t" of proximal electrode 106-1 described with reference to Fig. 7.

[0081] The proximal electrode 106-1 or 106-2 may have any suitable wall thickness "t." In some embodiments, the proximal electrode 106-1 or 106-2 has a maximum thickness measured perpendicular to the axis LL of the deflectable element 22 of at least 0.20 mm and an inner diameter D in the range of 2 mm to 6 mm.

[0082] Proximal electrode 106-2 may have any suitable width measured parallel to the direction of elongation of deflectable element 22, between 2 and 10 mm.

[0083] The proximal electrode 106-2 is formed from a thermally conductive material that provides for dissipation of heat generated during electroporation and / or RF ablation, and may be any suitable thermally conductive material, such as, but not limited to, platinum, palladium, or gold.

[0084] The proximal electrodes 106-2 may each be formed as a flat electrode wrapped around the outer surface of the deflectable element 22 to form a ring, or as two half rings connected together around the deflectable element 22.

[0085] Each proximal electrode 106-2, 106-1 (FIG. 7), 21 (FIGS. 5A and 5B) has a non-uniform surface that bulges away from the outer surface of the deflectable element 22. The proximal electrodes may have any suitable shape. For example, the proximal electrodes 21, 106-1, 106-2 may be formed as a ring having a uniform outer diameter along the width of the proximal electrode 21.

[0086] Reference is now made to FIG. 9, which is a schematic illustration of a balloon catheter 200 in a deployed configuration, constructed and operative in accordance with yet another alternative embodiment of the present invention. Catheter 200 is substantially similar to catheter 40 of FIG. 2, except that catheter 200 includes an inflatable distal tip assembly 202 including an inflatable balloon 204 having electrodes 206 (only some of which are labeled for simplicity) disposed thereon. Catheter 200 includes irrigation tubes 208 disposed within deflectable element 22 and extending into a region 210 surrounded by inflatable balloon 204. Electrodes 206 of expandable distal tip assembly 202 include irrigation holes 212 (only some of which are labeled for simplicity) in fluid communication with irrigation tube 208. Catheter 200 includes proximal electrodes 214 having substantially the same configuration as proximal electrodes 21 described with reference to FIGS. 5A and 5B. In some embodiments, proximal electrode 214 may replace proximal electrode 106-1 of FIG. 7 or proximal electrode 106-2 of FIG.

[0087] The term "about" or "approximately" used herein in connection with any numerical value or range of values ​​indicates a suitable dimensional tolerance that enables a portion of a component or a collection of components to function in accordance with its intended purpose as described herein. More specifically, "about" or "approximately" may refer to a range of values ​​of ±20% of the recited value, for example, "about 90%" may refer to a range of values ​​of 72% to 108%.

[0088] Various features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination.

[0089] The above-described embodiments are cited by way of example, and the present invention is not limited to what has been particularly shown and described in the foregoing specification. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described above, as well as variations and modifications thereof not disclosed in the prior art that will occur to those skilled in the art upon reading the foregoing description.

[0090] [Embodiment] (1) A medical system comprising a catheter configured to be inserted into a body part of a living subject, the catheter comprising: a deflectable element extending along a longitudinal axis from a proximal portion to a distal end; an expandable distal end assembly disposed proximate the distal end of the deflectable element, the expandable distal end assembly including a plurality of electrodes arranged about the longitudinal axis, the expandable distal end assembly configured to expand from a collapsed configuration to an expanded deployed configuration; a proximal electrode disposed adjacent the expandable distal tip assembly and proximate the distal end of the deflectable element, the proximal electrode extending circumferentially around the deflectable element and including an irrigation hole through which irrigation fluid is supplied; an irrigation tube disposed within the deflectable element and configured to be in fluid communication with the irrigation hole of the proximal electrode. (2) The system of embodiment 1, wherein the expandable distal end assembly includes at least one of an expandable basket having a plurality of splines on which the electrodes are disposed, or an inflatable balloon on which the electrodes are disposed. (3) The system described in embodiment 1, wherein the irrigation holes are arranged radially around the proximal electrode. (4) The system described in embodiment 3, wherein the irrigation holes are arranged longitudinally along the longitudinal axis and radially around the proximal electrode. (5) The system described in embodiment 1, wherein the irrigation holes are arranged longitudinally along the proximal electrode.

[0091] (6) The system of embodiment 1, wherein the proximal electrode and the deflectable element define an annular hollow therebetween, the irrigation tube is connected to transport irrigation fluid within the hollow, and the irrigation tube is in fluid communication with the irrigation hole through the hollow. (7) an ablation power generator connected to the catheter and configured to apply an electrical signal between at least one of the electrodes and the proximal electrode; an irrigation reservoir configured to store irrigation fluid; 2. The system of claim 1, further comprising: a pump connected to the irrigation reservoir and the catheter and configured to pump the irrigation fluid from the irrigation reservoir through the irrigation hole and via the irrigation tube. (8) The system of embodiment 7, wherein the ablation power generator is configured to apply the electrical signal between at least one of the electrodes and the proximal electrode to electroporate tissue of the body part. (9) The system of embodiment 7, wherein the proximal electrode and the deflectable element define an annular hollow therebetween, the irrigation tube is connected to transport the irrigation fluid within the hollow, the irrigation tube is in fluid communication with the irrigation hole through the annular hollow, and the pump is configured to pump the irrigation fluid from the irrigation reservoir through the irrigation tube into the annular hollow and out of the irrigation hole. (10) The system of embodiment 1, further comprising a separate irrigation tube disposed within the deflectable element and configured to deliver irrigation fluid within the area encompassed by the expandable distal end assembly.

[0092] (11) The system of embodiment 10, wherein the electrode of the expandable distal end assembly includes an irrigation hole in fluid communication with the separate irrigation tube. (12) A medical system comprising a catheter configured to be inserted into a body part of a living subject, the catheter comprising: a deflectable element having a distal end extending along an axis; an expandable distal end assembly disposed at the distal end of the deflectable element, the expandable distal end assembly including a plurality of electrodes and configured to expand from a collapsed configuration to an expanded deployed configuration; a proximal electrode disposed at the distal end of the deflectable element proximal to the expandable distal end assembly and extending circumferentially around the deflectable element, the proximal electrode having a maximum thickness measured perpendicular to the axis of the deflectable element of at least about 0.20 mm and an inner diameter in the range of about 2 mm to about 6 mm. (13) The system of embodiment 12, wherein the expandable distal end assembly includes at least one of an expandable basket having a plurality of splines on which the electrodes are disposed, or an inflatable balloon on which the electrodes are disposed. (14) The system of embodiment 12, further comprising an ablation power generator connected to the catheter and configured to apply an electrical signal between at least one of the electrodes and the proximal electrode. (15) The system of embodiment 14, wherein the ablation power generator is configured to apply the electrical signal between at least one of the electrodes and the proximal electrode to electroporate tissue of the body part.

[0093] (16) The system of embodiment 12, further comprising an irrigation tube disposed within the deflectable element and configured to deliver irrigation fluid within an area encompassed by the expandable distal end assembly. (17) The system of embodiment 16, wherein the electrode of the expandable distal end assembly includes an irrigation hole in fluid communication with the irrigation tube. (18) A medical system including a catheter, the catheter comprising: a deflectable element having a distal end; an expandable distal end assembly disposed at the distal end of the deflectable element, the expandable distal end assembly including a plurality of electrodes and configured to expand from a collapsed configuration to an expanded deployed configuration; a proximal electrode disposed at the distal end of the deflectable element proximal to the expandable distal tip assembly and extending circumferentially around the deflectable element, the proximal electrode and the distal end of the deflectable element defining an annular region therebetween; a thermally conductive material disposed in the annular region, the thermally conductive material being formed from a different material than the proximal electrode. (19) The system of embodiment 18, wherein the expandable distal end assembly is selected from the group consisting of an expandable basket having a plurality of splines, the electrodes disposed on the splines, or an inflatable balloon, the electrodes disposed on a surface of the balloon. (20) The system of embodiment 18, further comprising an ablation power generator connected to the catheter and configured to apply an electrical signal between at least one of the electrodes and the proximal electrode.

[0094] (21) The system of embodiment 20, wherein the ablation power generator is configured to apply the electrical signal between at least one of the electrodes and the proximal electrode to electroporate tissue of the body part. (22) The system of embodiment 18, further comprising an irrigation tube disposed within the deflectable element and configured to deliver irrigation fluid within an area encompassed by the expandable distal end assembly. (23) The system of embodiment 18, wherein the electrode of the expandable distal end assembly includes an irrigation hole in fluid communication with the irrigation tube.

Claims

1. 1. A medical system comprising a catheter configured to be inserted into a body part of a living subject, the catheter comprising: a deflectable element extending along a longitudinal axis from a proximal portion to a distal end; an expandable distal end assembly disposed proximate the distal end of the deflectable element, the expandable distal end assembly including a plurality of splines arranged about the longitudinal axis and a plurality of electrodes disposed on the plurality of splines, the expandable distal end assembly being configured to expand from a collapsed configuration to an expanded, deployed configuration, each spline of the plurality of splines having a portion for forming a hinge, the portion having a reduced thickness relative to the remainder of the spline; a proximal electrode disposed adjacent the expandable distal tip assembly and proximate the distal end of the deflectable element, the proximal electrode extending circumferentially around the deflectable element and including an irrigation hole through which irrigation fluid is supplied; an irrigation tube disposed within the deflectable element and configured to be in fluid communication with the irrigation hole of the proximal electrode; the proximal electrode and the deflectable element define an annular hollow therebetween, the irrigation tube is coupled to convey the irrigation fluid into the annular hollow, and the irrigation tube is in fluid communication with the irrigation hole through the annular hollow; A system wherein irrigation fluid collected in the annular hollow acts to cool the outer surface of the proximal electrode.

2. an ablation power generator connected to the catheter and configured to apply an electrical signal between at least one of the electrodes and the proximal electrode; an irrigation reservoir configured to store the irrigation fluid; 10. The system of claim 1, further comprising: a pump connected to the irrigation reservoir and the catheter and configured to pump the irrigation fluid from the irrigation reservoir, through the irrigation lumen, and via the irrigation tube.

3. 3. The system of claim 2, wherein the ablation power generator is configured to apply the electrical signal between at least one of the electrodes and the proximal electrode to electroporate tissue of the body part.

4. The system of claim 2 , wherein the pump is configured to pump the irrigation fluid from the irrigation reservoir through the irrigation tube into the annular hollow and out of the irrigation hole.

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