Patent Description:
A wide range of medical procedures involve placing probes, such as catheters, within a patient's body. Location sensing systems have been developed for tracking such probes. Magnetic location sensing is one of the methods known in the art. In magnetic location sensing, magnetic field generators are typically placed at known locations external to the patient. A magnetic field sensor within the distal end of the probe generates electrical signals in response to these magnetic fields, which are processed to determine the coordinate locations of the distal end of the probe. These methods and systems are described in <CIT>, <CIT>, <CIT>, <CIT>,<CIT> and <CIT>, in <CIT>, and in <CIT> and <CIT> and <CIT>. Locations may also be tracked using impedance or current based systems.

One medical procedure in which these types of probes or catheters have proved extremely useful is in the treatment of cardiac arrhythmias. Cardiac arrhythmias and atrial fibrillation in particular, persist as common and dangerous medical ailments, especially in the aging population.

Diagnosis and treatment of cardiac arrhythmias include mapping the electrical properties of heart tissue, especially the endocardium, and selectively ablating cardiac tissue by application of energy. Such ablation can cease or modify the propagation of unwanted electrical signals from one portion of the heart to another. The ablation process destroys the unwanted electrical pathways by formation of non-conducting lesions. Various energy delivery modalities have been disclosed for forming lesions, and include use of microwave, laser and more commonly, radiofrequency energies to create conduction blocks along the cardiac tissue wall. In a two-step procedure, mapping followed by ablation, electrical activity at 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 a multiplicity of points. These data are then utilized to select the endocardial target areas at which the ablation is to be performed.

Electrode catheters have been in common use in medical practice for many years. They are used to stimulate and map electrical activity in the heart and to ablate sites of aberrant electrical activity. In use, the electrode catheter is inserted into a major vein or artery, e.g., femoral vein, and then guided into the chamber of the heart of concern. A typical ablation procedure involves the insertion of a catheter having a one or more electrodes at its distal end into a heart chamber. A reference electrode may be provided, generally taped to the skin of the patient or by means of a second catheter that is positioned in or near the heart. RF (radio frequency) current is applied through the tip electrode(s) of the ablating catheter, and current flows through the media that surrounds it, i.e., blood and tissue, between the tip electrode(s) and an indifferent electrode. The distribution of current depends on the amount of electrode surface in contact with the tissue as compared to blood, which has a higher conductivity than the tissue. Heating of the tissue occurs due to its electrical resistance. The tissue is heated sufficiently to cause cellular destruction in the cardiac tissue resulting in formation of a lesion within the cardiac tissue which is electrically non-conductive.

Irreversible electroporation (IRE) applies short electrical pulses that generate high enough electrical fields (typically greater than <NUM> Volts per centimeter) to irreversibly damage the cells. Non-thermal IRE may be used in treating different types of tumors and other unwanted tissue without causing thermal damage to surrounding tissue. Small electrodes are placed in proximity to target tissue to apply short electrical pulses. The pulses increase the resting transmembrane potential, so that nanopores form in the plasma membrane. When the electricity applied to the tissue is above the electric field threshold of the target tissue, the cells become permanently permeable from the formation of nanopores. As a result, the cells are unable to repair the damage and die due to a loss of homeostasis and the cells typically die by apoptosis.

IRE may be used for cardiac ablation as an alternative to other cardiac ablation techniques, e.g., radio-frequency (RF) cardiac ablation. IRE cardiac ablation is sometimes referred to as Pulse Field Ablation (PFA). As IRE is generally a low thermal technique, IRE may reduce the risk of collateral cell damage that is present with the other techniques. e.g., in RF cardiac ablation.

<CIT>, describes cardiac tissue ablation catheters including an inflatable and flexible toroidal or spherically shaped balloon disposed at a distal region of an elongate member, a flexible circuit carried by an outer surface of the balloon, the flexible circuit including, a plurality of flexible branches conforming to the radially outer surface of the balloon, each of the plurality of flexible branches including a substrate, a conductive trace carried by the substrate, and an ablation electrode carried by the substrate, the ablation electrode in electrical communication with the conductive trace, and an elongate shaft comprising a guidewire lumen extending in the elongate member and extending from a proximal region of the inflatable balloon to distal region of the inflatable balloon and being disposed within the inflatable balloon, wherein a distal region of the elongate shaft is secured directly or indirectly to the distal region of the inflatable balloon.

<CIT>, describes a tissue electrode assembly including a membrane configured to form an expandable, conformable body that is deployable in a patient. The assembly further includes a flexible circuit positioned on a surface of the membrane and comprising at least one base substrate layer, at least one insulating layer and at least one planar conducting layer. An electrically-conductive electrode covers at least a portion of the flexible circuit and a portion of the surface of the membrane not covered by the flexible circuit, wherein the electrically-conductive electrode is foldable upon itself with the membrane to a delivery conformation having a diameter suitable for minimally-invasive delivery of the assembly to the patient.

<CIT>, describes a system for determining electrophysiological data comprising an electronic control unit configured to acquire electrophysiology signals from a plurality of electrodes of one or more catheters, select at least one clique of electrodes from the plurality of electrodes to determine a plurality of local E field data points, determine the location and orientation of the plurality of electrodes, process the electrophysiology signals from the at least one clique from a full set of bipole sub-cliques to derive the local E field data points associated with the at least one clique of electrodes, derive at least one orientation independent signal from the at least one clique of electrodes from the information content corresponding to weighted parts of electrogram signals, and display or output catheter orientation independent electrophysiologic information to a user or process.

<CIT>, describes medical devices for ablating nerves perivascularly and methods for making and using the same. An example medical device may include an expandable frame slidably disposed within a catheter shaft. The expandable frame may be configured to shift between a collapsed configuration and an expanded configuration. One or more electrodes may be disposed on a surface of the expandable frame. The one or more electrodes may be disposed radially inward relative to the greatest radial extent of the expandable frame when the expandable frame is in the expanded configuration.

<CIT>, describes an acoustic imaging system for use within a heart has a catheter, an ultrasound device incorporated into the catheter, and an electrode mounted on the catheter. The ultrasound device directs ultrasonic signals toward an internal structure in the heart to create an ultrasonic image, and the electrode is arranged for electrical contact with the internal structure. A chemical ablation device mounted on the catheter ablates at least a portion of the internal structure by delivery of fluid to the internal structure. The ablation device may include a material that vibrates in response to electrical excitation, the ablation being at least assisted by vibration of the material. The ablation device may alternatively be a transducer incorporated into the catheter, arranged to convert electrical signals into radiation and to direct the radiation toward the internal structure. The electrode may be a sonolucent structure incorporated into the catheter.

<CIT>, describes a medical apparatus, used to acquire electrical activity of patient anatomy, which includes an elongated body and a tip portion coupled to the elongated body. The tip portion includes one or more inflatable sections. Each inflatable section has a plurality of electrodes disposed on one of: (i) an outer surface of the one or more inflatable sections; and (ii) an inner surface and the outer surface of the one or more inflatable sections. The one or more inflatable sections, when inflated, cause a portion of the plurality of electrodes to contact a surface of an organ and provide a pathway for physiological fluid to flow through the tip portion. In one embodiment, the tip portion is a tulip balloon tip portion. In another embodiment, the tip portion is an inflatable tip portion having one or more concentrically wound inflatable sections.

<CIT> describes electroporation systems and methods of energizing a catheter for delivering electroporation. A catheter for delivering electroporation includes a distal section and an electrode assembly. The distal section is configured to be positioned in a vein within a body. The vein defines a central axis. The electrode assembly is coupled to the distal section and includes a structure and a plurality of electrodes distributed thereabout. The structure is configured to at least partially contact the vein. Each of the electrodes is configured to be selectively energized to form a circumferential ring of energized electrodes that is concentric with the central axis of the vein.

<CIT> discloses a system and method for local electrophysiological characterization of cardiac substrate using multi-electrode catheters. Disclosed is a system for determining electrophysiological data comprising an electronic control unit configured to acquire electrophysiology signals from a plurality of electrodes of one or more catheters, select at least one clique of electrodes from the plurality of electrodes to determine a plurality of local E field data points, determine the location and orientation of the plurality of electrodes, process the electrophysiology signals from the at least one clique from a full set of bipole subcliques to derive the local E field data points associated with the at least one clique of electrodes, derive at least one orientation independent signal from the at least one clique of electrodes from the information content corresponding to weighted parts of electrogram signals, and display or output catheter orientation independent electrophysiologic information to a user or process.

<CIT>describes a system for neuromodulation with a flexible catheter comprising a proximal electrode and a distal therapeutic assembly comprising multiple electrodes which can have the same polarity.

The invention is defined in independent claim <NUM>, further embodiments are described in the dependent claims.

Methods of surgery described here below are not claimed but are helpful for understanding the invention.

There is provided in accordance with an embodiment of the present invention, a medical system including a catheter configured to be inserted into a body part of a living subject, and including a deflectable element having a distal end, an expandable distal end assembly disposed at the distal end of the deflectable element, and including a plurality of assembly 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, and extending circumferentially around the deflectable element, at least one electrical connection configured to electrically connect together at least two of the assembly electrodes to act as a combined assembly electrode, and an ablation power generator configured to be connected to the catheter, and apply an electrical signal between the combined assembly electrode and a selected electrode.

Further in accordance with an embodiment of the present invention the selected electrode is the proximal electrode.

Still further in accordance with an embodiment of the present invention the at least one electrical connection permanently electrically connects together the at least two assembly electrodes to act as the combined assembly electrode.

Additionally, in accordance with an embodiment of the present invention the at least one electrical connection is configured to electrical connect together all of the assembly electrodes to act as the combined assembly electrode.

Moreover, in accordance with an embodiment of the present invention the at least one electrical connection permanently electrically connects together all of the assembly electrodes to act as the combined assembly electrode.

Further in accordance with an embodiment of the present invention the expandable distal end assembly includes at least one of an expandable basket including a plurality of splines, the electrodes being disposed on the splines, or an inflatable balloon with the electrodes disposed thereon.

Still further in accordance with an embodiment of the present invention the proximal electrode includes irrigation holes through which to irrigate the body part, the catheter also including an irrigation tube disposed in the deflectable element and configured to be in fluid communication with the irrigation holes of the proximal electrode.

Additionally, in accordance with an embodiment of the present invention the irrigation holes are disposed radially around the proximal electrode.

Moreover, in accordance with an embodiment of the present invention the irrigation holes are disposed longitudinally along the proximal electrode.

Further in accordance with an embodiment of the present invention the proximal electrode and the deflectable element define an annular hollow therebetween, the irrigation tube being coupled to transfer irrigation fluid into the hollow, the irrigation tube being in fluid communication with the irrigation holes via the hollow.

Still further in accordance with an embodiment of the present invention, the system includes an irrigation reservoir configured to store irrigation fluid, and a pump configured to be connected to the irrigation reservoir and the catheter, and to pump the irrigation fluid from the irrigation reservoir through the irrigation holes via the irrigation tube.

Additionally, in accordance with an embodiment of the present invention the ablation power generator is configured to apply the electrical signal between the combined assembly electrode and the proximal electrode to perform electroporation of tissue of the body part.

Moreover, in accordance with an embodiment of the present invention, the system includes an irrigation tube disposed in the deflectable element and configured to deliver irrigation fluid into a region surrounded by the expandable distal end assembly.

Further in accordance with an embodiment of the present invention the proximal electrode has a maximum thickness measured perpendicular to the axis of the deflectable element of at least <NUM> and an inner diameter in the range of <NUM> to <NUM>.

According to the present invention the proximal electrode and the distal end of the deflectable element define an annular region therebetween, the catheter also including thermally conductive material disposed in the annular region, the thermally conductive material being formed from a different material than the proximal electrode.

There is also provided in accordance with another embodiment of the present invention, a medical system including a catheter configured to be inserted into a body part of a living subject, and including a deflectable element having a distal end, an expandable distal end assembly disposed at the distal end of the deflectable element, and including a plurality of assembly electrodes, and configured to expand from a collapsed form to an expanded deployed form, at least one electrical connection permanently electrically connecting together at least two of the assembly electrodes to act as a combined assembly electrode, and an ablation power generator configured to be connected to the catheter, and apply an electrical signal to the combined assembly electrode so as to ablate tissue of the body part.

Additionally, in accordance with an embodiment of the present invention the at least one electrical connection permanently electrically connects together all of the assembly electrodes to act as the combined assembly electrode.

Moreover, in accordance with an embodiment of the present invention the expandable distal end assembly includes at least one of an expandable basket including a plurality of splines, the electrodes being disposed on the splines, or an inflatable balloon with the electrodes disposed thereon.

Further in accordance with an embodiment of the present invention the ablation power generator is configured to apply the electrical signal to the combined assembly electrode so as to perform electroporation of tissue of the body part.

A balloon catheter or another catheter with an expandable distal end assembly such as a basket catheter may include electrodes on the distal end assembly that may be used for ablation, such as RF ablation or IRE ablation. In order to ablate a large area, a physician may need to reposition the catheter in order to adequately cover the area. This is time consuming.

Embodiments of the present invention solve the above problem by electrically connecting some or all of the electrodes of a distal end assembly of a catheter to act as a combined assembly electrode. An ablation power generator, connected to the catheter, applies an electrical signal to the combined assembly electrode to perform ablation (e.g., electroporation) of the tissue of the body part.

A return electrode may be used so that the ablation current is applied between the combined assembly electrode of the distal end assembly electrodes and a return electrode. In some cases, when the return electrode is one of the electrodes on the distal end assembly or in the middle of the distal end assembly, the ablation current may avoid travelling through the tissue thereby reducing the efficacy of the ablation current. Therefore, in some embodiments, the catheter includes a proximal electrode placed proximally to the distal end assembly. The ablation power generator applies an electrical signal between the combined assembly electrode and the proximal electrode to perform ablation (e.g., electroporation) of tissue of the body part.

Placing the return electrode proximally to the expandable distal end assembly helps prevent the ablation current from travelling inside the distal end assembly. However, due to the concentration of the ablation energy at the proximal return electrode, the proximal return electrode may overheat or cause charring of tissue.

Embodiments of the present invention solve the above problems by providing an irrigated proximal electrode, which is placed at the distal end of a deflectable element of the catheter, proximally to the distal end assembly. The proximal electrode extends circumferentially around the deflectable element, and includes irrigation holes through which to irrigate the body part to prevent overheating and charring. An irrigation tube placed in the deflectable element is in fluid communication with the irrigation holes of the proximal electrode. The irrigation holes are generally placed radially around, and longitudinally along, the proximal electrode.

In some embodiments, the proximal electrode and the deflectable element define an annular hollow therebetween with the irrigation tube coupled to transfer irrigation fluid into the hollow so that the irrigation tube is in fluid communication with the irrigation holes via the hollow. A pump pumps irrigation fluid from an irrigation reservoir via the irrigation tube into the hollow and out of the irrigation holes.

The ablation power generator is connected to the catheter, and applies an electrical signal between the combined assembly electrode and the proximal electrode to perform radio-frequency (RF) ablation or electroporation of the tissue of the body part.

In some embodiments, the expandable distal end assembly is also irrigated. A second irrigation tube may be placed in the deflectable element and delivers irrigation fluid into a region surrounded by the expandable distal end assembly. In some embodiments, the electrodes of the expandable distal end assembly (e.g., a balloon assembly) include irrigation holes that are 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.

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. Thermally conductive material is placed in the annular region to dissipate heat from the tissue around 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.

In other embodiments, the proximal electrode is formed from a thick piece of thermally conductive material to dissipate heat from the tissue around 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 <NUM> and an inner diameter in the range of about <NUM> to <NUM>.

Reference is now made to <FIG>, which is a schematic view of a medical system <NUM> constructed and operative in accordance with an exemplary embodiment of the present invention. The system <NUM> includes a catheter <NUM> configured to be inserted into a body part of a living subject (e.g., a patient <NUM>). A physician <NUM> navigates the catheter <NUM> (for example, a basket catheter produced Biosense Webster, Inc. of Irvine, CA, USA), to a target location in a heart <NUM> of the patient <NUM>, by manipulating an elongated deflectable element <NUM> of the catheter <NUM>, using a manipulator <NUM> near a proximal end of the catheter <NUM>, and/or deflection from a sheath <NUM>. In the pictured embodiment, physician <NUM> uses catheter <NUM> to perform electro-anatomical mapping of a cardiac chamber and ablation of cardiac tissue.

Catheter <NUM> includes an expandable distal end assembly <NUM> (e.g., a basket assembly), which is inserted in a folded configuration, through sheath <NUM>, and only after the catheter <NUM> exits sheath <NUM> does the distal end assembly <NUM> regain its intended functional shape. By containing distal end assembly <NUM> in a folded configuration, sheath <NUM> also serves to minimize vascular trauma on its way to the target location.

Catheter <NUM> includes a plurality of electrodes <NUM> disposed on the expandable distal end assembly <NUM> for sensing electrical activity and/or applying ablation power to ablate tissue of the body part (inset <NUM>). The catheter <NUM> also includes a proximal electrode <NUM> disposed on the deflectable element <NUM> proximal to the expandable distal end assembly <NUM>. Catheter <NUM> may incorporate a magnetic position sensor (not shown) at the distal edge of deflectable element <NUM> (i.e., at the proximal edge of the distal end assembly <NUM>). Typically, although not necessarily, the magnetic sensor is a Single-Axis Sensor (SAS). A second magnetic sensor (not shown) may be included at any suitable position on the assembly <NUM>. The second magnetic sensor may be a Triple-Axis Sensor (TAS) or a Dual-Axis Sensor (DAS), or a SAS by way of example only, based for example on sizing considerations. The magnetic sensors, the proximal electrode <NUM>, and electrodes <NUM> disposed on the assembly <NUM> are connected by wires running through deflectable element <NUM> to various driver circuitries in a console <NUM>.

In some embodiments, system <NUM> comprises a magnetic-sensing subsystem to estimate an ellipticity of the basket assembly <NUM> of catheter <NUM>, as well as its elongation/retraction state, inside a cardiac chamber of heart <NUM> by estimating the elongation of the basket assembly <NUM> from the distance between the magnetic sensors. Patient <NUM> is placed in a magnetic field generated by a pad containing one or more magnetic field generator coils <NUM>, which are driven by a unit <NUM>. The magnetic fields generated by coil(s) <NUM> transmit alternating magnetic fields into a region where the body-part is located. The transmitted alternating magnetic fields generate signals in the magnetic sensors, which are indicative of position and/or direction. The generated signals are transmitted to console <NUM> and become corresponding electrical inputs to processing circuitry <NUM>.

The method of position and/or direction sensing using external magnetic fields and magnetic sensors, is implemented in various medical applications, for example, in the CARTO® system, produced by Biosense-Webster, and is described in detail in <CIT>, <CIT>,<CIT>, <CIT>, <CIT> and<CIT>, in <CIT>, and in <CIT>, <CIT> and <CIT>.

Processing circuitry <NUM>, typically part of a general-purpose computer, is further connected via a suitable front end and interface circuits <NUM>, to receive signals from body surface-electrodes <NUM>. Processing circuitry <NUM> is connected to body surface-electrodes <NUM> by wires running through a cable <NUM> to the chest of patient <NUM>.

In an embodiment, processing circuitry <NUM> renders to a display <NUM>, a representation <NUM> of at least a part of the catheter <NUM> and a mapped body-part, responsively to computed position coordinates of the catheter <NUM>.

Processing circuitry <NUM> is typically programmed in software to carry out the functions described herein. The software may be downloaded to the computer in electronic form, over a network, for example, or it may, alternatively or additionally, be provided and/or stored on non-transitory tangible media, such as magnetic, optical, or electronic memory.

The medical system <NUM> may also include an ablation power generator <NUM> (such as an RF signal generator) configured to be connected to the catheter <NUM>, and apply an electrical signal between one or more of the electrodes <NUM> and the proximal electrode <NUM>. The medical system <NUM> may also include an irrigation reservoir <NUM> configured to store irrigation fluid, and a pump <NUM> configured to be connected to the irrigation reservoir <NUM> and the catheter <NUM>, and to pump the irrigation fluid from the irrigation reservoir <NUM> via an irrigation tube through irrigation holes of the catheter <NUM> as described in more detail with reference to <FIG> and <FIG>.

The example illustration shown in <FIG> is chosen purely for the sake of conceptual clarity. <FIG> shows only elements related to the disclosed techniques for the sake of simplicity and clarity. System <NUM> typically comprises additional modules and elements that are not directly related to the disclosed techniques, and thus are intentionally omitted from <FIG> and from the corresponding description. The elements of system <NUM> and the methods described herein may be further applied, for example, to control an ablation of tissue of heart <NUM>.

Reference is now made to <FIG> and <FIG>. <FIG> is a schematic view of the catheter <NUM> in a deployed form constructed and operative in accordance with an embodiment of the present invention. <FIG> is a schematic view of the distal end of the catheter <NUM> of <FIG> in a collapsed form.

The catheter <NUM> is configured to be inserted into a body part (e.g., the heart <NUM> (<FIG>)) of a living subject. The deflectable element <NUM> of the catheter <NUM> has a distal end <NUM>. The deflectable element <NUM> may be produced from any suitable material, for example, polyurethane or polyether block amide. The assembly <NUM> is disposed distally to the deflectable element <NUM> and may be connected to the deflectable element <NUM> via a proximal coupling member <NUM> at the distal end <NUM>. The proximal coupling member <NUM> typically comprises a hollow tube and may be formed from any suitable material, for example, but not limited to polycarbonate with or without glass filler, polyether ether ketone (PEEK) with or without glass filler, polyimide, polyamide, or Polyetherimide (PEI) with or without glass filler. The coupling member <NUM> may formed as an integral part of the deflectable element <NUM> or as part of the distal end assembly <NUM> or as a separate element which connects with the deflectable element <NUM> and the distal end assembly <NUM>.

The assembly <NUM>, which may include a basket assembly, may include multiple splines such as flexible strips <NUM> (only one labeled for the sake of simplicity) with the electrodes <NUM> disposed on the splines. In the embodiments of <FIG> and <FIG> each flexible strip <NUM> includes a single electrode <NUM> (only some labeled for the sake of simplicity). The assembly <NUM> may include any suitable number of electrodes <NUM> with multiple electrodes <NUM> per strip <NUM>.

In the embodiment of <FIG> and <FIG>, each flexible strip <NUM> is formed of Nitinol which is selectively covered with insulating material (for example, thermoplastic polymer resin shrink wrap (PET)) in the distal and proximal regions <NUM> (only some labeled for the sake of simplicity) of the flexible strips <NUM> leaving a central region <NUM> (only some labeled for the sake of simplicity) of the flexible strips <NUM> as an electrically active region to perform mapping and/or perform ablation or electroporation, by way of example. The structure of the assembly <NUM> may vary. For example, flexible strips <NUM> (or other splines) may include flexible printed circuit boards (PCBs), or a shape-memory alloy such as Nitinol. The electrically active region of each flexible strip <NUM> may be larger or smaller than that shown in <FIG>, and/or more centrally or proximally disposed on each flexible strip <NUM>.

Embodiments described herein refer mainly to a basket distal-end assembly <NUM>, purely by way of example. In alternative embodiments, the disclosed techniques can be used with any other suitable type of distal-end assembly.

The distal end assembly <NUM> includes a distal portion <NUM>, and a proximal portion <NUM>, and is configured to expand from a collapsed form (shown in <FIG>) to an expanded deployed form (shown in <FIG>). The relaxed state of the distal end assembly <NUM> is the expanded deployed form shown in <FIG>. The distal end assembly <NUM> is configured to collapse into the collapsed form when the catheter <NUM> is retracted in a sheath <NUM> (<FIG>) and is configured to expand to the expanded deployed form when the catheter <NUM> is removed from the sheath <NUM>. The relaxed shape of the distal end assembly <NUM> may be set by forming the flexible strips <NUM> from any suitable resilient material such as Nitinol or PEI. In some embodiments, the relaxed state of the expandable distal end assembly <NUM> may be the collapsed form, and the expandable distal end assembly <NUM> is expanded using a pull wire or element connected to the distal portion <NUM> and fed through a lumen in the deflectable element <NUM>.

The proximal electrode <NUM> is disposed at the distal end <NUM> of the deflectable element <NUM> proximally to the expandable distal end assembly <NUM>, and generally extends circumferentially around the deflectable element <NUM>. The proximal electrode <NUM> includes irrigation holes <NUM> (only some labeled for the sake of simplicity) through which to irrigate the body part. The irrigation holes <NUM> are generally disposed radially around, and/or longitudinally along, the proximal electrode <NUM>. The irrigation holes may have any suitable diameter, for example, in the range of <NUM> to <NUM> microns. The holes may be formed using any suitable technique, for example, laser drilling or electrical discharge machining (EDM). The proximal electrode <NUM> may include any suitable number of holes, for example, in the range of <NUM> to <NUM> holes. In one example, the proximal electrode <NUM> includes <NUM> proximally disposed holes and <NUM> distally disposed holes. An additional irrigation tube <NUM> is disposed in element <NUM> as explained in greater detail subsequently.

The ablation power generator <NUM> (<FIG>) is configured to be connected to the catheter <NUM>, and apply an electrical signal between at least one of the electrodes <NUM> and the proximal electrode <NUM>. In some embodiments, the ablation power generator <NUM> is configured to apply the electrical signal between at least one of the electrodes <NUM> and the proximal electrode <NUM> to perform electroporation of tissue of the body part.

Reference is now made to <FIG> and <FIG>. <FIG> is a cross-sectional view of the distal end of the catheter <NUM> of <FIG>. <FIG> is a more detailed cross-sectional view of the distal end of the catheter <NUM> inside block B of <FIG>.

The distal ends of the flexible strips <NUM> (only two labeled for the sake of simplicity) are folded over and connected to a distal connector <NUM>, which in some embodiments is a tube (e.g., polymer tube) or slug (e.g., polymer slug). The distal connector <NUM> may be formed from any suitable material, for example, but not limited to polycarbonate with or without glass filler, PEEK with or without glass filler, or PEI with or without glass filler. In some embodiments, the flexible strips <NUM> may be connected to the distal connector <NUM> without being folded over so that when the distal end assembly <NUM> is collapsed the flexible strips <NUM> are approaching a flat formation along their length. The proximal ends of the flexible strips <NUM> are connected to the proximal coupling member <NUM>. The flexible strips <NUM> may be connected to the distal connector <NUM> and the proximal coupling member <NUM> using a suitable adhesive, such as an epoxy adhesive.

In some embodiments, the catheter <NUM> includes a nose cap <NUM> inserted into the distal connector <NUM>. The nose cap <NUM> may be used to help secure the flexible strips <NUM> to the distal connector <NUM>. The nose cap <NUM> may be formed from any suitable material, for example, but not limited to polycarbonate with or without glass filler, PEEK with or without glass filler, or PEI with or without glass filler. The nose cap <NUM> may optionally be sized to provide a pressure fit against the flexible strips <NUM> to prevent the flexible strips <NUM> from being pulled away from the inner surface of the distal connector <NUM>.

In some embodiments, the thickness of the distal portions of the flexible strips <NUM> may be reduced (compared to the rest of the flexible strips <NUM>) to create hinges <NUM> (one hinge <NUM> per flexible strip <NUM>) to allow the flexible strips <NUM> to bend sufficiently between the collapsed form and the deployed expanded form of the expandable distal end assembly <NUM>. Only two of the hinges <NUM> are labeled for the sake of simplicity. The hinges <NUM> of the flexible strips <NUM> may be reinforced using a flexible material such as a yarn (not shown). The hinges <NUM> (including the yarn and covering layers) may have any suitable thickness, for example, in the range of about <NUM> to <NUM> microns. The yarn may comprise any one or more of the following: an ultra-high-molecular-weight polyethylene yarn; or a yarn spun from a liquid-crystal polymer. The yarn may be any suitable linear density, for example, in a range between about <NUM> denier and <NUM> denier.

Reference is now made to <FIG> and <FIG>. <FIG> is a cross-sectional view of the catheter <NUM> of <FIG> along line A:A. <FIG> is a cross-sectional view of the catheter of <FIG> along line B:B.

<FIG> and <FIG> show the proximal electrode <NUM> which extends circumferentially around the deflectable element <NUM>. The edges of the proximal electrode <NUM> may be connected to the deflectable element <NUM> using a suitable adhesive and/or using a covering such as a thermoplastic polymer resin shrink wrap. <FIG> and <FIG> show some of the irrigation holes <NUM> (only some labeled for the sake of simplicity) in the proximal electrode <NUM>. The proximal electrode <NUM> may have any suitable length measured parallel to the direction of elongation of the deflectable element <NUM>, for example, in the range of about <NUM> and <NUM>.

The catheter <NUM> includes an irrigation tube <NUM> disposed in the deflectable element <NUM> and configured to be in fluid communication with the irrigation holes <NUM> of the proximal electrode <NUM>. The pump <NUM> (<FIG>) is configured to be connected to the irrigation reservoir <NUM> (<FIG>) and the catheter <NUM>, and to pump the irrigation fluid from the irrigation reservoir <NUM> through the irrigation holes <NUM> via the irrigation tube <NUM>.

The inner surface of the proximal electrode <NUM> and the deflectable element <NUM> define an annular hollow <NUM> therebetween. The irrigation tube <NUM> is coupled to the annular hollow <NUM> to transfer the irrigation fluid into the hollow <NUM>. The irrigation tube <NUM> is generally disposed on the other side of the annular hollow <NUM> to the irrigation holes <NUM>. Therefore, the irrigation tube <NUM> is in fluid communication with the irrigation holes <NUM> via the hollow <NUM>. The pump <NUM> (<FIG>) is configured to pump the irrigation fluid from the irrigation reservoir <NUM> via the irrigation tube <NUM> into the hollow <NUM> and out of the irrigation holes <NUM>. The collection of the irrigation fluid in the annular hollow <NUM> acts to cool the outer surface of the proximal electrode <NUM> and not just the portions close to the irrigation holes <NUM>.

The catheter <NUM> may include another irrigation tube <NUM> disposed in the deflectable element <NUM> and configured to deliver irrigation fluid into a region <NUM> (<FIG>) surrounded by the flexible strips <NUM> of the expandable distal end assembly <NUM>. The irrigation tube <NUM> typically extends into the expandable distal end assembly <NUM> as shown in <FIG> and <FIG>.

In some embodiments, the catheter <NUM> includes a position sensor <NUM> (such as a magnetic position sensor) disposed in the deflectable element <NUM>. <FIG> and <FIG> also show wires <NUM> disposed therein connecting the electrodes <NUM>, the proximal electrode <NUM>, and the position sensor <NUM> with the proximal end of the catheter <NUM>.

Reference is now made to <FIG>, which is a schematic view of a catheter <NUM> in a deployed form constructed and operative in accordance with an alternative embodiment of the present invention. The catheter <NUM> is substantially the same as the catheter <NUM> of <FIG> and <FIG> except for the following differences. The catheter <NUM> includes a proximal electrode <NUM>, which is not irrigated. The proximal electrode <NUM> may either be cooled by filling with a thermally conductive material as described with reference to a proximal electrode <NUM>-<NUM> of <FIG>, or by forming the proximal electrode from a thermally conductive material of sufficient thickness to dissipate heat as described with reference to a proximal electrode <NUM>-<NUM> of <FIG>.

Reference is now made to <FIG>, which is a cross-sectional view of the catheter <NUM> of <FIG> along line C:C. The proximal electrode <NUM>-<NUM> and the distal end of the deflectable element <NUM> define an annular region <NUM> therebetween. The catheter <NUM> includes thermally conductive material <NUM>, which is disposed in the annular region <NUM>, generally, but not necessarily, filling the annular region <NUM>, and generally in contact with at least part of the inner surface of the proximal electrode <NUM>-<NUM>. The thermally conductive material <NUM> may be formed from a different material than the proximal electrode <NUM>-<NUM>.

The term "thermally conductive material", as used in the specification and claims, is defined as a material with a thermal conductivity greater than or equal to <NUM> Watt per meter Kelvin (W/mK) at <NUM> degrees Centigrade. The thermally conductive material <NUM> may be any suitable thermally conductive material, for example, but not limited to, platinum, palladium, gold, or thermally conductive epoxy. In some embodiments, the thermally conductive material <NUM> is first wrapped around the outer surface of the deflectable element <NUM>, and then the proximal electrode <NUM>-<NUM> is wrapped around the thermally conductive material <NUM>. In other embodiments, the proximal electrode <NUM>-<NUM> is first fixed around the deflectable element <NUM> (as a single piece or from two halves subsequently joined together) and then the thermally conductive material <NUM> is injected below the proximal electrode <NUM>-<NUM> through a hole (not shown) in the proximal electrode <NUM>-<NUM>.

The wall thickness of the proximal electrode <NUM>-<NUM> may have any suitable value, for example, in the range of about <NUM> to <NUM>. The thickness of the thermally conductive material <NUM> may have any suitable value, for example, in the range of about <NUM> to <NUM>. The proximal electrode <NUM>-<NUM> may have any suitable length measured parallel to the direction of elongation of the deflectable element <NUM>, for example, between about <NUM> and <NUM>.

It should be noted that the irrigation tube <NUM> (<FIG> and <FIG>) is not included within the deflectable element <NUM> shown in <FIG>.

Reference is now made to <FIG>, which is a cross-sectional view of the catheter <NUM> of <FIG> along line C:C constructed and operative in accordance with another alternative embodiment of the present invention. The proximal electrode <NUM>-<NUM> shown in <FIG> has a wall thickness which is greater than the wall thickness of the proximal electrode <NUM>-<NUM> described with reference to <FIG>.

The proximal electrode <NUM>-<NUM> may have any suitable wall thickness. In some embodiments, the proximal electrode <NUM>-<NUM> may have a maximum thickness measured perpendicular to the axis of the deflectable element <NUM> of at least <NUM> and an inner diameter in the range of <NUM> to <NUM>.

The proximal electrode <NUM>-<NUM> may have any suitable length measured parallel to the direction of elongation of the deflectable element <NUM> of between about <NUM> and <NUM>.

The proximal electrode <NUM>-<NUM> is formed from a thermally conductive material, which provides dissipation of heat formed during electroporation and/or RF ablation. The thermally conductive material may be any suitable thermally conductive material, for example, but not limited to, platinum, palladium, or gold.

The proximal electrode <NUM>-<NUM> may each be formed as a flat electrode which is wound around the outer surface of the deflectable element <NUM> to form a ring or as two half rings which are connected together around the deflectable element <NUM>.

Each proximal electrode <NUM>-<NUM>, <NUM>-<NUM> (<FIG>), <NUM> (<FIG> and <FIG>), has a non-uniform surface, which bulges away from the outer surface of the deflectable element <NUM>. The proximal electrodes may have any suitable shape. For example, the proximal electrode <NUM>, <NUM>-<NUM>, <NUM>-<NUM> may be formed as ring having a uniform outer diameter along the length of the proximal electrode <NUM>.

Reference is now made to <FIG>, which is a schematic view of a balloon catheter <NUM> in a deployed form constructed and operative in accordance with yet another alternative embodiment of the present invention. The catheter <NUM> is substantially the same as the catheter <NUM> of <FIG> except that the catheter <NUM> includes an expandable distal end assembly <NUM>, which includes an inflatable balloon <NUM> with the electrodes <NUM> (only some labeled for the sake of simplicity) disposed thereon. The catheter <NUM> includes an irrigation tube <NUM> which is disposed in the deflectable element <NUM> and extends into a region <NUM> surrounded by the inflatable balloon <NUM>. The electrodes <NUM> of the expandable distal end assembly <NUM> include irrigation holes <NUM> (only some labeled for the sake of simplicity) that are in fluid communication with the irrigation tube <NUM>. The catheter <NUM> includes a proximal electrode <NUM> in substantially the same form as the proximal electrode <NUM> described with reference to <FIG> and <FIG>. In some embodiments, the proximal electrode <NUM> may be replaced with the proximal electrode <NUM>-<NUM> of <FIG> or with the proximal electrode <NUM>-<NUM> of <FIG>.

Reference is now made to <FIG>, which is a schematic view of electrode connections in the catheter <NUM> of medical system <NUM> constructed and operative in accordance with an exemplary embodiment of the present invention.

The catheter <NUM> may include one or more electrical connections <NUM> configured to electrically connect together at least two (and optionally all) of the assembly electrodes <NUM> to act as a combined assembly electrode <NUM>.

In some embodiments, the electrical connection(s) <NUM> may be configured to selectively connect together the assembly electrodes <NUM> to act as the combined assembly electrode <NUM> and also allow the electrodes <NUM> to act as individual electrodes, for example, for sensing positions, electrical activations, and performing individual ablation. In such embodiments, the electrical connections <NUM> may include switching circuitry (not shown) which enables selectively connecting together two or more (and optionally all) of the assembly electrodes <NUM>.

In other embodiments, the electrical connection(s) <NUM> permanently electrically connects together the at least two (and optionally all) of the assembly electrodes <NUM> to act as the combined assembly electrode <NUM>.

The ablation power generator <NUM> is configured to be connected to the catheter <NUM>, and apply an electrical signal (arrow <NUM>) to the combined assembly electrode <NUM> so as to ablate tissue of the body part. In some embodiments, the ablation power generator <NUM> is configured to apply the electrical signal <NUM> to the combined assembly electrode <NUM> so as to perform electroporation of tissue of the body part.

The electrical signal <NUM> is generally applied between the combined assembly electrode <NUM> and a return electrode. The return electrode may be located in any suitable location, for example, on the catheter <NUM>, as an indifferent electrode attached to the patient's skin or on another catheter. In some embodiments, the proximal electrode <NUM> acts as the return electrode.

Therefore, in some embodiments, the ablation power generator <NUM> is configured to apply an electrical signal between the combined assembly electrode <NUM> and the proximal electrode <NUM>. In some embodiments, the ablation power generator <NUM> is configured to apply the electrical signal between the combined assembly electrode <NUM> and the proximal electrode <NUM> to perform electroporation of tissue of the body part.

As previously mentioned, the ablation may lead to excessive heating in the region of the proximal electrode <NUM>. Therefore, the proximal electrode <NUM> may apply cooling to surrounding tissue using irrigation as described above with reference to <FIG>, <FIG> and <FIG>.

The electrical connections <NUM> may be implemented with other catheters to connect assembly electrodes together to form a combined assembly electrode.

In some embodiments, two or more (and optionally all) of the assembly electrodes <NUM> (<FIG>) of the catheter <NUM> may be connected (selectively or permanently) using the electrical connections <NUM>. The proximal electrode <NUM> (<FIG>) or any other suitable electrode may act as the return electrode. The proximal electrode <NUM> may provide cooling using the thermally conductive material <NUM> disposed in the annular region <NUM> (<FIG>) of the proximal electrode <NUM>, as described in more detail above with reference to <FIG>. Alternatively, the proximal electrode <NUM> may provide cooling by forming the proximal electrode <NUM> (<FIG>) from a thermally conductive material having a maximum thickness measured perpendicular to the axis of the deflectable element of at least <NUM> and an inner diameter in the range of <NUM> to <NUM>, as described in more detail above with reference to <FIG>.

In some embodiments, two or more (and optionally all) of the electrodes <NUM> of the expandable distal end assembly <NUM> of the catheter <NUM> of <FIG> may be connected (selectively or permanently) using the electrical connections <NUM>. The proximal electrode <NUM> (<FIG>) or any other suitable electrode may act as the return electrode.

Various features of the invention which are, for clarity, described in the contexts 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 sub-combination.

Claim 1:
A medical system (<NUM>) comprising a catheter (<NUM>) configured to be inserted into a body part of a living subject, and including:
a deflectable element (<NUM>) having a distal end (<NUM>);
an expandable distal end assembly (<NUM>) disposed at the distal end of the deflectable element, and comprising a plurality of assembly electrodes (<NUM>), and configured to expand from a collapsed form to an expanded deployed form;
a proximal electrode (<NUM>) disposed at the distal end of the deflectable element proximally to the expandable distal end assembly, and extending circumferentially around the deflectable element;
at least one electrical connection (<NUM>) configured to electrically connect together at least two of the assembly electrodes to act as a combined assembly electrode; and
an ablation power generator (<NUM>) configured to be connected to the catheter, and apply an electrical signal between the combined assembly electrode and a selected electrode,
characterized in that the proximal electrode and the distal end of the deflectable element define an annular region (<NUM>) therebetween, the catheter also including thermally conductive material (<NUM>) disposed in the annular region, the thermally conductive material being formed from a different material than the proximal electrode.