Catheter sensing and flushing

Abstract

The ablation system of the present disclosure helps to safely form wide and deep lesions. For example, the ablation system of the present disclosure can allow irrigation fluid and blood to flow through the expandable ablation electrode, thereby enabling efficient and effective cooling of the ablation electrode when the ablation electrode delivers energy at the patient's treatment site. Additionally or alternatively, the ablation system of the present disclosure may include a deformable ablation electrode and a plurality of sensors that cooperatively detect deformation of the ablation electrode to provide a reliable indication of the degree and direction of contact between the ablation electrode and tissue at the treatment site.

Description

[0001] This application is a divisional application of the Chinese patent application with application number 201780041499.2 filed on May 2, 2017 and entitled “Catheter Sensing and Flushing”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of U.S. Provisional Application No. 62 / 330,395, filed May 2, 2016, U.S. Provisional Application No. 62 / 357,704, filed July 1, 2016, U.S. Provisional Application No. 62 / 399,632, filed September 26, 2016, U.S. Provisional Application No. 62 / 399,625, filed September 26, 2016, U.S. Provisional Application No. 62 / 420,610, filed November 11, 2016, and U.S. Provisional Application No. 62 / 420,611, filed November 11, 2016. Provisional Application No. 62 / 424,736, filed on April 21, 2016, priority to U.S. Provisional Application No. 62 / 428,406, filed on November 30, 2016, priority to U.S. Provisional Application No. 62 / 434,073, filed on December 14, 2016, priority to U.S. Provisional Application No. 62 / 468,339, filed on March 7, 2017, and priority to U.S. Provisional Application No. 62 / 468,873, filed on March 8, 2017, the entire contents of which are incorporated herein by reference.

[0004] This application is also related to the following commonly owned U.S. patent applications filed on the same date as this application: Attorney Docket No. AFRA-0009-P01, entitled "Lesion Formation"; Attorney Docket No. AFRA-00010-P01, entitled "Pulsed Radiofrequency Ablation"; Attorney Docket No. AFRA-0011-P01, entitled "Therapeutic Catheter with Imaging", and Attorney Docket No. AFRA-0013-P01, entitled "Catheter Insertion". Each of the foregoing applications is hereby incorporated by reference in its entirety. Background Art

[0005] Abnormal rhythms, often referred to as arrhythmias, can occur in the heart. Arrhythmias occur when abnormal conduction in the myocardial tissue alters the typical heartbeat pattern. Radiofrequency ("RF") catheter ablation can be used to create lesions that interrupt the mechanism of abnormal conduction to terminate certain arrhythmias. Summary of the invention

[0006] The ablation system disclosed in the present application helps to safely form wide and deep lesions. For example, the ablation system disclosed in the present application can allow irrigation fluid and blood to flow through the expandable ablation electrode, thereby efficiently and effectively cooling the ablation electrode when the ablation electrode delivers energy at the patient's treatment site. Additionally, or alternatively, the ablation system disclosed in the present application may include a deformable ablation electrode and a plurality of sensors that cooperatively detect deformation of the ablation electrode to provide a reliable indication of the degree and direction of contact between the ablation electrode and tissue at the treatment site.

[0007] According to one aspect, a catheter includes a catheter shaft, an irrigation element, and an ablation electrode. The catheter shaft has a proximal portion and a distal portion, and the catheter shaft defines an inner cavity extending from the proximal portion to the distal portion. The irrigation element is coupled to the distal portion of the catheter shaft, and the irrigation element defines an irrigation hole in fluid communication with the inner cavity. The ablation electrode is coupled to the catheter shaft, and the ablation electrode has an inner portion and an outer portion opposite to the inner portion, wherein the irrigation hole of the irrigation element is directed toward the inner portion of the ablation electrode.

[0008] In some embodiments, at least some of the irrigation ports can have a maximum dimension, and a ratio of the maximum dimension of each irrigation port to a corresponding vertical distance between the irrigation port and an inner portion of the ablation electrode in the absence of external force applied to the ablation electrode can be greater than about 0.02 and less than about 0.2.

[0009] In some embodiments, the total area of ​​the flushing ports may be greater than about 0.05 mm 2 and less than about 0.5 mm 2 .

[0010] In some embodiments, the ablation electrode may be coated with an irrigation element. Additionally or alternatively, the volume defined by the interior portion of the ablation electrode in the expanded state is greater than the volume defined by the irrigation element in the expanded state. For example, in the absence of an external force applied to the ablation electrode, the ablation electrode includes a portion contained between a first radius and a second radius, the first radius and the second radius being within 30% of each other. As an additional or alternative example, in the absence of an external force applied to the ablation electrode, the ablation electrode includes a substantially spherical portion. In some cases, the ablation electrode may also or alternatively include a substantially conical proximal region.

[0011] In some embodiments, the irrigation element is expandable. For example, the irrigation element in the expanded state may include an ellipsoidal portion.

[0012] In certain embodiments, the ablation electrode is expandable.

[0013] In some embodiments, the irrigation ports may be spaced circumferentially and axially along the irrigation element.

[0014] In certain embodiments, at least a portion of the irrigation port can be arranged to direct fluid in a distal direction relative to the ablation electrode, and at least a portion of the irrigation port can be arranged to direct fluid in a proximal direction relative to the ablation electrode.

[0015] In some embodiments, the irrigation element can include one of a non-compliant balloon or a semi-compliant balloon.

[0016] In certain embodiments, the flushing element may be a resilient, expandable structure.

[0017] In some embodiments, the irrigation element may include a porous membrane.

[0018] In certain embodiments, the irrigation element may include an open-cell foam.

[0019] In some embodiments, at least one of the irrigation element or the ablation electrode is expandable to have a cross-sectional dimension that is greater than a cross-sectional diameter of the catheter shaft.

[0020] In some embodiments, the irrigation element can be electrically isolated from the ablation electrode.

[0021] In some embodiments, the irrigation element can be electrically isolated from the ablation electrode over a predetermined frequency range.

[0022] In certain embodiments, the catheter may further include a central electrode disposed along the irrigation element.

[0023] In some embodiments, the irrigation element can be thermally isolated from the ablation electrode.

[0024] In certain embodiments, the catheter may further include a thermocouple disposed along the irrigation element.

[0025] In some embodiments, the catheter further comprises a handle coupled to the proximal portion of the catheter shaft, the handle comprising a drive portion configured to drive deflection of the catheter shaft.

[0026] In some embodiments, the catheter may further include a plurality of sensors, the ablation electrode includes a deformable portion, and the plurality of sensors are supported on the deformable portion of the ablation electrode. For example, when an external force applied along the deformable portion of the ablation electrode exceeds a threshold force, at least one of the sensors may move to contact the irrigation element. Continuing with this example, in some cases, when the deformable portion of the ablation electrode is in an uncompressed state, none of the plurality of sensors is in contact with the irrigation element.

[0027] According to another aspect, a method for ablating tissue of a human patient may include positioning an ablation electrode at a treatment site (the ablation electrode having an outer portion disposed toward the tissue and an inner portion opposite the outer portion), directing energy to a portion of the outer portion of the ablation electrode, and providing an irrigation fluid flow in the inner portion of the electrode in the absence of an external force applied to the ablation electrode, the irrigation fluid flow having a Reynolds coefficient greater than approximately 2300 in the inner portion of the ablation electrode.

[0028] In some embodiments, providing a flow of irrigation liquid includes pumping irrigation liquid through a plurality of irrigation ports defined by an irrigation element coated with an ablation electrode, and the irrigation element and the ablation electrode are each coupled to a distal portion of the catheter shaft. For example, pumping irrigation liquid through the irrigation ports may include directing at least a portion of the irrigation liquid in a distal direction to the irrigation element and directing at least a portion of the irrigation liquid in a proximal direction to the irrigation element.

[0029] In some embodiments, the method can further include delivering the ablation electrode and the irrigation element to the tissue treatment site. For example, the ablation electrode and the irrigation element can each be coupled to a distal portion of the catheter shaft, and delivering the ablation electrode and the irrigation element to the tissue treatment site includes moving the ablation electrode and the irrigation element, each in a retracted state, through an 8F introducer sheath.

[0030] According to another aspect, a catheter may include a catheter shaft, an irrigation element, and an ablation electrode. The catheter shaft may have a proximal portion and a distal portion, the catheter shaft defining an inner cavity extending from the proximal portion to the distal portion. The irrigation element may be coupled to the distal portion of the catheter shaft, the irrigation element being in fluid communication with the inner cavity. The ablation electrode may be coupled to the catheter shaft. The ablation electrode has an inner portion and an outer portion opposite the inner portion. Additionally, or alternatively, the ablation electrode may include a deformable portion that is elastically compliant from a compressed state to an uncompressed state, the inner portion of the ablation electrode along the deformable portion being closer to at least a portion of the surface of the irrigation element in the compressed state than in the uncompressed state.

[0031] In certain embodiments, the ablation electrode is movable from an uncompressed state to a compressed state by a pressure greater than about 5 g.

[0032] In some embodiments, the flushing element defines a plurality of flushing ports in fluid communication with the lumen, more than one of the plurality of flushing ports being arranged along the flushing element to direct fluid along the deformable portion toward the inner portion of the ablation electrode. For example, the flushing element may include a porous membrane. Additionally or alternatively, the flushing element includes an open-cell foam material. Further, or alternatively, in the expanded state, the flushing element may include an ellipsoidal portion (e.g., a balloon). In some cases, the flushing ports are spaced circumferentially and axially along the flushing element. In some cases, at least a portion of the flushing ports are arranged to direct fluid in a distal direction relative to the ablation electrode, and at least a portion of the flushing ports are arranged to direct fluid in a proximal direction relative to the ablation electrode.

[0033] In some embodiments, the deformable portion of the ablation electrode can be elastically compliant in the axial direction relative to the catheter axis and in the radial direction relative to the catheter axis. Additionally or alternatively, in the uncompressed state, the deformable portion of the ablation electrode can be coated with an irrigation element. In some cases, the irrigation element can be expanded from the delivery state to the expanded state.

[0034] In some embodiments, the ablation electrode can have a conductive surface having an open area greater than about 50% and less than about 95% along both the inner portion and the outer portion.

[0035] In some embodiments, the ablation electrode can be a mesh.

[0036] In some embodiments, the ablation electrode is a braid.

[0037] In some embodiments, the ablation electrode is formed of nitinol. For example, the ablation electrode can be formed of coated nitinol. As an example, the coating can be gold tantalum, or a combination thereof.

[0038] In some embodiments, the ablation electrode is at least partially radiopaque.

[0039] In certain embodiments, the irrigation element may include a balloon formed from one or more of: thermoplastic polyurethane, silicone, poly(ethylene terephthalate), and polyether block amide.

[0040] In some embodiments, the catheter may further include a plurality of sensors supported on the deformable portion of the ablation electrode. For example, when a threshold force on the deformable portion of the ablation electrode is exceeded, at least one of the sensors may move to contact the irrigation element. Additionally or alternatively, when the deformable portion of the ablation electrode is in an uncompressed state, in some cases, none of the plurality of sensors supported on the deformable portion of the ablation electrode is in contact with the irrigation element. The deformable portion of the ablation electrode, in the uncompressed state, as an example, may include, for example, an ellipsoidal portion, and the sensors of the plurality of sensors are spaced apart from each other in a circumferential direction along an inner portion of the ellipsoidal portion of the ablation electrode. For example, the sensors of the plurality of sensors are evenly spaced apart in a circumferential direction along the ellipsoidal portion of the inner portion of the ablation electrode. Further, or alternatively, the plurality of sensors include a first group of sensors and a second group of sensors, the first group of sensors being disposed distally of the second group of sensors along the inner portion of the ablation electrode. In some cases, the sensors of the plurality of sensors are substantially evenly distributed along the inner portion of the ablation electrode. Furthermore, or alternatively, at least one of the sensors includes a radiopaque portion. Additionally, or alternatively, the catheter further includes at least one radiopaque marker disposed on the ablation electrode (eg, supported on at least one of the sensors).

[0041] In certain embodiments, the irrigation element and the deformable portion of the ablation electrode can be folded to a size for delivery through an 8F introducer sheath.

[0042] According to another aspect, a catheter ablation system includes a catheter and a controller. The catheter may include a catheter shaft, an irrigation element and an ablation electrode, and a plurality of sensors. The catheter shaft may have a proximal portion and a distal portion, the catheter shaft defining an inner cavity extending from the proximal portion to the distal portion. The irrigation element may be coupled to the distal portion of the catheter shaft, the irrigation element being in fluid communication with the inner cavity. The ablation electrode may be coupled to the catheter shaft, the ablation electrode having an inner portion and an outer portion opposite the inner portion. The ablation electrode may include a deformable portion that is elastically compliant from a compressed state to an uncompressed state, the inner portion of the ablation electrode along the deformable portion being closer to at least a portion of the surface of the irrigation element in the compressed state than in the uncompressed state. A plurality of sensors may be supported on the deformable portion of the ablation electrode. The controller may be configured to: i) receive a measurement generated by an electrical signal generated between at least one sensor and another electrode; ii) determine a state of the deformable portion of the ablation electrode based at least in part on the measurement.

[0043] In some embodiments, the determined state of the deformable portion of the ablation electrode corresponds to a shape of the deformable portion of the ablation electrode.

[0044] In some embodiments, the controller may be further configured to send an indication of the determined shape of the deformable portion of the ablation electrode to a graphical user interface.

[0045] In certain embodiments, the controller may be further configured to transmit electrical energy between the at least one sensor and the irrigation element, and the received measurement is based on the electrical energy between the at least one sensor and the irrigation element.

[0046] In some embodiments, the catheter ablation system may further include a central electrode disposed about the irrigation element, wherein the controller is further configured to send electrical energy between the at least one sensor and the central electrode, and the received measurements are based on the electrical energy between the at least one sensor and the central electrode.

[0047] According to yet another aspect, a method for determining the shape of an ablation catheter may include receiving measurements resulting from electrical signals generated between at least one sensor supported on a deformable portion of an ablation electrode and another electrode, determining, based at least in part on the measurements, whether the deformable portion of the ablation electrode is in contact with an irrigation element coated by the deformable portion of the ablation electrode, and sending an indication of the determined contact between the deformable portion of the ablation electrode and the irrigation element to a graphical user interface.

[0048] In some embodiments, determining the shape of the deformable portion of the ablation catheter can include determining a three-dimensional shape of the deformable portion of the ablation catheter.

[0049] According to another aspect, a method for manufacturing an ablation catheter includes coupling an irrigation element to a distal portion of a catheter shaft so that the irrigation element is in fluid communication with an inner cavity defined by the catheter shaft, forming a deformable portion of an ablation electrode, positioning the deformable portion of the ablation electrode relative to the irrigation element so that an inner portion of the ablation electrode covers the irrigation element, and coupling the deformable portion of the ablation electrode to the catheter shaft relative to the irrigation element, wherein the inner portion of the ablation electrode is movable between a compressed state and an uncompressed state along the deformable portion, and the inner portion of the ablation electrode is closer to at least a portion of a surface of the irrigation element in the compressed state than in the uncompressed state.

[0050] In certain embodiments, forming the deformable portion of the ablation electrode can include removing material from a tube of material (eg, nitinol) and bending the tube of material into a substantially closed shape.

[0051] In some embodiments, forming the deformable portion of the ablation electrode can include removing material from a flat sheet of material (e.g., nitinol) and bending the flat sheet of material into a three-dimensional shape. For example, removing material from the flat sheet of material can include laser cutting the flat sheet of material. Additionally, or alternatively, removing material from the flat sheet of material can include chemically etching the flat sheet of material.

[0052] According to yet another aspect, a catheter may include a catheter shaft having a proximal portion and a distal portion, an ablation electrode coupled to the distal portion of the catheter shaft. The ablation electrode may include struts coupled to each other at a connection point to collectively define a plurality of apertures. Each of the plurality of apertures is defined, and the coupled struts are movable relative to each other such that a maximum radial dimension of the ablation electrode increases by at least two times when the coupled struts are moved relative to each other to transition the ablation electrode from a compressed state in the presence of an external force to an uncompressed state in the absence of the external force.

[0053] In some embodiments, the pillars can be in electrical communication with each other to form a single electrical conductor.

[0054] In certain embodiments, the struts are movable relative to each other to allow the ablation electrode to self-expand from a compressed state to an uncompressed state.

[0055] In some embodiments, the ablation electrode can include an inner portion and an outer portion opposite the inner portion, and the inner portion is in fluid communication with the outer portion through a plurality of apertures.

[0056] In certain embodiments, in an uncompressed state, at least some of the struts can extend circumferentially relative to an axis defined by the proximal and distal end portions of the catheter shaft.

[0057] In some embodiments, the ablation electrode has a maximum axial dimension that changes less than about 33% when the coupled struts move relative to each other, and the ablation electrode is expanded from an uncompressed state to a compressed state when a radial force applied to an outer portion of the ablation electrode changes.

[0058] In certain embodiments, in an uncompressed state, the maximum radial dimension of the ablation electrode is at least about 20% greater than the outer diameter of the distal portion of the catheter shaft.

[0059] In some embodiments, the ablation electrode can be bulbous in an uncompressed state.

[0060] In some embodiments, the catheter shaft can define a central axis extending from the proximal portion to the distal portion, and at least some of the plurality of holes have respective symmetry planes that pass through the respective holes and contain the central axis of the catheter shaft. For example, each of the plurality of holes is symmetric about its respective symmetry plane in the compressed state and the uncompressed state of the ablation electrode.

[0061] In some embodiments, the catheter shaft can define a central axis extending from the proximal portion to the distal portion, and at least some of the plurality of holes have respective planes of symmetry passing through the distal ends of the holes, the proximal ends of the holes, and the central axis.

[0062] In certain embodiments, the ablation electrode can include a distal region and a proximal region, the proximal region coupled to a distal portion of the catheter, and struts coupled to each other along the distal region to define a closed shape along the distal region of the ablation electrode.

[0063] In some embodiments, at least some of the plurality of apertures can have a larger area in an uncompressed state of the ablation electrode than in a compressed state of the ablation electrode.

[0064] In certain embodiments, the ablation electrode can be delivered through an 8 Fr sheath in a compressed state.

[0065] In some embodiments, the strain in the ablation electrode can be less than about ten percent in the compressed state.

[0066] In certain embodiments, at least some of the plurality of pores are substantially diamond-shaped in an uncompressed state.

[0067] In some embodiments, each end of each strut can be coupled to an end of another strut or to a distal portion of a catheter shaft.

[0068] In some embodiments, the ablation electrode can have an outer portion and an inner portion opposite the outer portion, and each aperture can extend from the outer portion to the inner portion.

[0069] In some embodiments, the struts can be formed from Nitinol.

[0070] In some embodiments, a plurality of holes can be disposed circumferentially and axially around the ablation electrode.

[0071] In some embodiments, each of the struts can define a portion of at least two apertures.

[0072] In certain embodiments, a combined area of ​​the plurality of apertures along the outer surface of the ablation electrode is greater than a combined area of ​​the struts along the outer surface of the ablation electrode.

[0073] In some embodiments, some of the struts may be wider than other of the struts. For example, at least some of the wider struts may be mechanically fixed relative to the distal portion of the catheter shaft. Additionally, or alternatively, other of the struts may be movable relative to the distal portion of the catheter shaft.

[0074] In certain embodiments, at least some of the struts comprise a non-uniform width along the length of the respective strut.

[0075] According to yet another aspect, a catheter may include a catheter shaft, an irrigation element, and an ablation electrode. The catheter shaft may have a proximal portion and a distal portion. The irrigation element may be positioned relative to the catheter shaft to direct irrigation liquid away from the distal portion of the catheter shaft. The ablation electrode may include a distal region and a proximal region, the proximal region coupled to the distal portion of the catheter shaft. The distal region may include struts coupled to each other to collectively define a plurality of holes. Each of the plurality of holes may be defined by at least four struts, and the struts may be coupled to each other to define a closed shape along the distal region, the closed shape of the distal region enveloping the irrigation element.

[0076] In some embodiments, the catheter may also include a fastener (e.g., a rivet) that couples the struts to each other to define a closed shape along the distal region. For example, the fastener may be formed of a first material and the struts are formed of a second material, the first material being different from the second material. Further, or alternatively, a portion of the struts may define respective eyelets, and the fastener extends through the eyelet to couple a portion of the struts to each other. For example, the eyelets may be aligned with each other. For example, the fastener may extend through the eyelet at the distal-most position of the ablation electrode. Additionally, or alternatively, the plurality of holes may include a first group of holes and a second group of holes. The first group of holes is defined by portions of the struts that define respective eyelets, the second group of holes is defined by struts that do not have eyelets, and the second group of holes is defined by fewer struts than the first group of holes.

[0077] In some embodiments, the catheter shaft can define a central axis extending from the proximal portion to the distal portion. For example, the central axis can extend through the fastener when no external force is applied to the ablation electrode.

[0078] In certain embodiments, each end of a strut can be coupled to an end of at least one other strut or to a distal portion of a catheter shaft.

[0079] In some embodiments, at least a portion of the ablation electrode is elastically compliant between a compressed state in the presence of an external force and an uncompressed state in the absence of an external force. For example, at least some of the plurality of holes have a larger area in the uncompressed state than in the compressed state. As a further or alternative example, the ablation electrode can self-expand from a compressed state to an uncompressed state. In some cases, the ablation electrode can be delivered through an 8Fr sheath. In some cases, the strain in the ablation electrode in the compressed state is less than about ten percent. Further or alternatively, the ablation electrode can be bulbous in the uncompressed state.

[0080] In certain embodiments, the struts can be formed from Nitinol.

[0081] In some embodiments, a plurality of holes can be disposed circumferentially and axially around the ablation electrode.

[0082] In some embodiments, each of the struts can define a portion of at least two apertures.

[0083] According to another aspect, a method of forming a catheter may include forming an ablation electrode having two open ends, the ablation electrode including struts that collectively define a first set of holes, a portion of the struts having a first end region coupled to another strut and a second end region that is uncoupled from each other strut, inserting fasteners through the corresponding second end regions of the portion of the struts to couple the second end regions to each other to define a second set of holes and close one of the two open ends of the ablation electrode, and coupling the ablation electrode to a distal portion of a catheter shaft.

[0084] In certain embodiments, the open end of the ablation electrode distal from the fastener can be coupled to the distal portion of the catheter shaft.

[0085] In some embodiments, the second end regions of the portion of struts are coupled to one another, and the ablation electrode is elastically compliant between a compressed state in the presence of an external force and an uncompressed state in the absence of an external force.

[0086] In certain embodiments, the second end region of each respective strut of the portion of the strut may define an eyelet, and inserting a fastener through the respective second end region of the portion of the strut may include aligning the eyelets of the second end region such that the fastener is inserted through the aligned eyelets.

[0087] In some embodiments, forming the ablation electrode may include removing material from the plate material to form the first set of holes. For example, removing material from the plate material may include one or more of laser cutting the plate material and chemically etching the plate material.

[0088] In some embodiments, forming the ablation electrode can include removing material from the tube of material to form the first set of holes. For example, removing material from the tube of material includes laser cutting the tube of material.

[0089] In some embodiments, the ablation electrode can be formed from Nitinol.

[0090] According to yet another aspect, a catheter may include a catheter shaft and an ablation electrode (e.g., formed of nitinol). The catheter shaft may have a proximal portion and a distal portion. The ablation electrode may be coupled to the distal portion of the catheter shaft and electrically connected to a power source. The ablation electrode may include a deformable portion that is elastically compliant between a compressed state and an uncompressed state. When current from the power source moves through the deformable portion of the ablation electrode, the current density of the deformable portion changes by less than about 10% in a uniform conductive medium 1 mm from an outer portion of the deformable portion in an uncompressed state.

[0091] In some embodiments, in the uncompressed state, the maximum radial dimension of the deformable portion is at least 20% greater than the maximum radial dimension of the catheter shaft. For example, in the compressed state, the deformable portion can be delivered through an 8Fr sheath.

[0092] In some embodiments, the deformable portion is substantially spherical in an uncompressed state.

[0093] In some embodiments, at least the deformable portion of the ablation electrode can include an electropolished surface.

[0094] In some embodiments, the deformable portion may include struts that collectively define a plurality of holes, each hole extending from an outer portion of the deformable portion to an inner portion of the deformable portion. For example, the area of ​​at least some of the holes in the uncompressed state may be greater than the area of ​​the corresponding hole in the compressed state.

[0095] In certain embodiments, the catheter shaft can define a central axis extending from the proximal portion to the distal portion, and the deformable portion can be symmetrical about a plane including the central axis.

[0096] According to another aspect, a catheter includes a catheter shaft and an ablation electrode. The catheter shaft may have a proximal portion and a distal portion. The ablation electrode may include a distal region and a proximal region, the proximal region coupled to the distal portion of the catheter shaft. The ablation electrode may be electrically connected to a power source. The ablation electrode may include struts that collectively define a plurality of holes, wherein the opening area of ​​the holes in the plurality of holes varies from the proximal region to the distal region of the ablation electrode, and the struts defining the plurality of holes are electrically conductive.

[0097] In some embodiments, the number of holes along a meridian of the distal region is less than the number of holes along a meridian passing through the largest radial dimension of the ablation electrode.

[0098] In some embodiments, the number of holes along a meridian of the proximal region is less than the number of holes along a meridian passing through the largest radial dimension of the ablation electrode.

[0099] In certain embodiments, the struts defining the plurality of apertures can have a substantially uniform width.

[0100] In some embodiments, the struts can include a first group of struts having a first width and a second group of struts having a second width different from the first width, and the first group of struts are axially spaced apart from the second group of struts.

[0101] In some embodiments, at least some of the struts may have a non-uniform width along the respective length of the struts. For example, the width of at least some of the struts increases along the respective length of the struts in a direction from the proximal region to the distal region of the ablation electrode.

[0102] According to yet another aspect, a catheter may include a catheter shaft and an ablation electrode. The catheter shaft has a proximal portion and a distal portion, and the ablation electrode is coupled to the distal portion of the catheter shaft. The ablation electrode includes a deformable portion that is elastically compliant between a compressed state and an uncompressed state, the deformable portion in the uncompressed state being positionable at a plurality of different angles relative to tissue at a treatment site, and for delivering the same amount of ablation energy from the deformable portion to the tissue at a certain amount of pressure between the deformable portion and the tissue, the deformable portion producing a lesion of substantially similar size at each of the plurality of different angles.

[0103] In certain embodiments, the plurality of different angles can include an axial direction defined by the catheter axis and a lateral direction perpendicular to the axial direction.

[0104] In some embodiments, the lesion at each of the plurality of different angles has a similar depth and a similar width corresponding to each of the plurality of different angles.

[0105] In certain embodiments, the lesions corresponding to each of the plurality of different angles have a depth that varies by less than about ±30%. For example, the lesions corresponding to each of the plurality of different angles have a depth that varies by about ±20%.

[0106] In some embodiments, the maximum transverse dimension of the deformable portion in the uncompressed state is at least 20% greater than the maximum transverse dimension of the catheter shaft.

[0107] In certain embodiments, the deformable portion includes an open frame through which a fluid may move through the frame to cool the deformable portion.

[0108] According to another aspect, a cardiac catheter includes a catheter shaft, a central electrode, a cover, and a surface electrode. The catheter shaft has a proximal portion and a distal portion. The central electrode is coupled to the distal portion of the catheter shaft. The cover is coupled to the distal portion of the catheter shaft, the cover is elastically compliant in response to an external force, and the cover covers the central electrode in the absence of the external force. The surface electrode can be disposed along the cover and spaced apart from the central electrode in the absence of an external force applied to the cover.

[0109] In certain embodiments, each surface electrode can be spaced apart from the center electrode by a distance greater than about 2 mm and less than about 6 mm in the absence of external forces applied to the housing.

[0110] In some embodiments, regardless of the orientation of the outer cover relative to the tissue, the outer cover can initially contact the tissue before the central electrode initially contacts the tissue.

[0111] In certain embodiments, the surface electrodes are non-coplanar with respect to each other in the absence of external forces applied to the housing.

[0112] In some embodiments, the housing can be an ablation electrode.

[0113] In certain embodiments, each surface electrode can be electrically isolated from the housing.

[0114] In some embodiments, the outer cover may include an outer portion opposite the inner portion, the outer cover defining a plurality of apertures extending from the outer portion to the inner portion.

[0115] In certain embodiments, the center electrode can be in fluid communication with an outer portion of the housing through a plurality of apertures.

[0116] In some embodiments, each surface electrode can be disposed along an exterior portion of the housing.

[0117] In certain embodiments, each surface electrode can be disposed along an interior portion of the housing.

[0118] In some embodiments, each surface electrode can extend through the housing from an exterior portion of the housing to an interior portion of the housing.

[0119] In some embodiments, in the absence of external forces, the maximum radial dimension of the outer cover is greater than the maximum radial dimension of the distal portion of the catheter shaft. For example, the maximum radial dimension of the outer cover can be at least about 20% greater than the maximum radial dimension of the distal portion of the catheter shaft.

[0120] In some embodiments, in the absence of external forces applied to the housing, at least a portion of the housing is substantially spherical.

[0121] In certain embodiments, the center electrode can be spaced distally from the distal end portion of the catheter shaft.

[0122] In some embodiments, the central electrode can be disposed on an irrigation element that is in fluid communication with the catheter shaft.

[0123] In certain embodiments, the central electrode can be disposed generally along a central axis defined by the catheter shaft.

[0124] According to another aspect, a system may include a catheter shaft, a central electrode, a cover, a surface electrode, and a catheter interface unit. The catheter shaft has a proximal portion and a distal portion. The central electrode is coupled to the distal portion of the catheter shaft. The cover is coupled to the distal portion of the catheter shaft, the cover is elastically compliant in response to an external force, and the cover covers the central electrode in the absence of the external force. The surface electrode is disposed along the cover and is spaced apart from the central electrode in the absence of an external force applied to the cover. The catheter interface unit includes a graphical user interface, one or more processors, and a non-transitory computer-readable storage medium having computer executable instructions stored thereon for causing the one or more processors to: acquire a plurality of electrograms, each respective electrogram being based on a difference between a first electrical signal and a second electrical signal, the first electrical signal being from a respective one of the surface electrodes, and the second electrical signal being from the central electrode, and displaying a representation of at least one of the plurality of electrograms on the graphical user interface.

[0125] In some embodiments, the computer-readable storage medium may also have stored thereon computer-executable instructions for causing one or more processors to determine a voltage map of the heart associated with the plurality of electrograms, the voltage map being based at least in part on the plurality of electrograms. Additionally or alternatively, the non-transitory computer-readable storage medium may have stored thereon computer-executable instructions for causing one or more processors to display the voltage map on a graphical user interface.

[0126] According to yet another aspect, a method of determining electrical activity associated with a patient's heart may include receiving a first electrical signal from a central electrode of a cardiac catheter, for use with a surface electrode disposed on a housing covering the central electrode, receiving a plurality of second electrical signals, each respective second electrical signal being associated with one of the surface electrodes, and determining a plurality of electrograms, each electrogram being based on a difference between a respective one of the second electrical signals and the first signal.

[0127] In certain embodiments, the center electrode can be at least about 2 mm and less than about 6 mm from each of the surface electrodes without external forces being applied to the housing covering the center electrode.

[0128] In some embodiments, the method may further include sending a representation of one or more of the electrograms to a graphical user interface.

[0129] In some embodiments, the method can further include determining a voltage map of the heart based at least in part on the plurality of electrograms.

[0130] In some embodiments, the method can further include sending electrical energy to an irrigation element of the cardiac catheter, wherein the central electrode is disposed along the irrigation element, and the electrical energy to the irrigation element reduces noise on one or more of the first electrical signal and the plurality of second electrical signals.

[0131] According to yet another aspect, a method for treating heart disease includes moving a distal region of a catheter shaft toward a chamber of a patient's heart, and for a cover coupled to the catheter shaft, expanding the cover so that a surface electrode disposed on the cover moves in a direction away from a central electrode enclosed by the cover and coupled to the catheter shaft, and selectively treating tissue of the chamber based on a plurality of electrograms, each electrogram being based on a difference between a first electrical signal from the central electrode and a second electrical signal from at least one surface electrode disposed on the cover.

[0132] In some embodiments, selectively treating tissue of the lumen can include delivering ablative energy to the tissue of the lumen.

[0133] In some embodiments, delivering ablative energy to tissue of the chamber includes delivering ablative energy to a housing having surface electrodes disposed on the housing.

[0134] Embodiments may include one or more of the following advantages.

[0135] In some embodiments, the irrigation port of the irrigation element is directed toward the interior portion of the ablation electrode. This configuration can help cool the ablation electrode through a combination of irrigation liquid and blood flow through the interior portion of the ablation electrode. For example, directing the irrigation liquid toward the interior portion of the ablation electrode can help move blood in the space between the introduction of the irrigation liquid and the interior portion of the ablation electrode. Therefore, compared to a closed cooling configuration, an embodiment including an irrigation port directed toward the interior portion of the ablation electrode can improve local cooling of the ablation electrode and / or reduce the possibility of blood clotting or charring at the treatment site.

[0136] In some embodiments, the ablation electrode can be expanded from a compressed state to an uncompressed state. Compared to non-expandable ablation electrodes, the expandable ablation electrode of the present disclosure can be delivered through a relatively small sheath (e.g., an 8 French sheath) while still having a large surface area through which energy can be safely delivered to tissue to produce damage in the tissue of the patient. In addition, or alternatively, the expandable ablation electrode of the present disclosure can have an open area through which blood can flow during treatment. Compared to ablation electrodes that are not affected by blood movement, the expandable ablation electrode of the present disclosure has a reduced effect on the natural movement of blood, thereby reducing the effect on the cooling provided by the natural movement of blood through the treatment site.

[0137] In certain embodiments, a sensor is disposed on a deformable portion of an expandable ablation electrode, and the sensor can be used to detect deformation of the deformable portion of the ablation electrode in one or more directions. In general, such a configuration of the sensor can provide information about the magnitude and direction of contact force applied to tissue by the expandable electrode, which, by extension, can have a larger surface area than a non-expandable electrode delivered through a sheath of a given size. More specifically, because the deformation of the deformable portion can be reproducible (e.g., substantially linear in some cases) as a function of force (e.g., over a range of forces associated with an ablation procedure), the deformation detected by the sensor is useful as feedback about the magnitude and direction of force applied to tissue by an expandable ablation electrode having a large surface area. Therefore, in combination with or in addition to the large surface area provided by the expandable ablation electrode, the deformation detectable by the sensor about the degree and / or direction of contact between the expandable ablation electrode and tissue can, for example, help apply appropriate force and safely apply energy to the tissue.

[0138] In some embodiments, the ablation electrode includes a deformable portion that is elastically compliant between a compressed state and an uncompressed state, and when current from a power source moves through the deformable portion in the uncompressed state, the deformable portion has a substantially uniform current density (e.g., the current density at 1 mm from the outer portion of the deformable portion varies by less than about ±10%). This substantially uniform current density distribution helps to produce reliable and repeatable large lesions using the expandable electrode. Additionally, or alternatively, the substantially uniform distribution of current density in the expandable electrode can help to form large lesions in a manner that is substantially independent of the orientation of the expandable electrode relative to the tissue.

[0139] Other aspects, features, and advantages will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0140] Figure 1 is a schematic diagram of the ablation system during ablation therapy.

[0141] Figure 2 yes Figure 1 Perspective view of the catheter of the ablation system.

[0142] Figure 3 yes Figure 1 A perspective view of the distal portion of a catheter of an ablation system.

[0143] Figure 4 is along Figure 3 A cross-sectional perspective view of section AA.

[0144] Figure 5 is moved from the flushing element to Figure 2 Schematic diagram of the jet of flushing liquid on the inner part of the ablation electrode of a catheter.

[0145] Figure 6 yes Figure 1 Side view of the ablation electrode of the ablation system.

[0146] Figure 7 yes Figure 1 A perspective view of an ablation electrode of an ablation system.

[0147] Figure 8 yes Figure 1 The ablation electrode of the ablation system Figure 7 Cross-sectional view of line BB in .

[0148] Fig. 9 yes Figure 1 An exemplary graph of displacement as a function of force of a deformable portion of an ablation electrode of an ablation system.

[0149] Fig.10 yes Figure 1 A perspective view of a sensor and ablation electrode of an ablation system, with the sensor shown mounted on the ablation electrode.

[0150] Fig.11 yes Figure 1 A perspective view of the sensors of the ablation system.

[0151] Figures 12A-12C is formed Figure 1 Schematic diagram of an ablation system and an ablation electrode approach.

[0152] Figures 13A-13E Yes Figure 2 Schematic diagram of the method of inserting a catheter into a patient's body.

[0153] Fig.14A -C is to Figure 1 A schematic diagram of a method of positioning an ablation electrode of an ablation system at a treatment site of a patient.

[0154] Fig.15A -B is flush Figure 1 Schematic diagram of an ablation system and an ablation electrode approach.

[0155] Fig.16 is a schematic diagram of a side view of a helical irrigation element of a catheter of an ablation system.

[0156] Fig.17 is a side view of an irrigation element of a catheter of an ablation system, the irrigation element including a porous membrane.

[0157] Fig.18is a perspective view of a distal portion of a catheter of an ablation system.

[0158] Fig.19 is a perspective view of a distal portion of a catheter of an ablation system.

[0159] Fig. 20 is along Fig.19 A cross-sectional perspective view of a cross section of DD.

[0160] Fig.21 is a perspective view of a distal portion of a catheter of an ablation system.

[0161] Fig. 22 is along Fig.21 EE cross section Fig.21 A side cross-sectional view of a catheter.

[0162] Fig.23 yes Fig.21 A perspective view of the flushing element of a catheter.

[0163] Fig.24 It is used to form Fig.23 A perspective view of the tube of the flushing element is shown.

[0164] Fig.25 The sensor is placed Fig.21 Schematic diagram of the ablation electrodes on the catheter.

[0165] Fig.26 It is around Fig.21 Schematic diagram of the trajectory of the outer surface of the ablation electrode of the catheter, which is used to present the simulation results of the current density associated with the ablation electrode.

[0166] Fig. 27 It is along Fig.26 The trace shown is a graph of the percent change in simulated current density at a fixed distance of 1 mm from the outer surface of the ablation electrode.

[0167] Fig.28 is used Fig.21 Graph of the depth and width of the lesion on a chicken breast as the ablation electrode is applied along the axial and lateral directions relative to the chicken breast.

[0168] Fig.29 is a side view of a deformable portion of an ablation electrode, the deformable portion of the ablation electrode including a generally conical proximal portion.

[0169] Like reference symbols in the various drawings indicate like elements. DETAILED DESCRIPTION

[0170] The present disclosure generally relates to systems and methods for ablating patient tissue during a medical procedure performed on an anatomical structure of the patient. As a non-limiting example and for clarity of explanation, the systems and methods of the present disclosure are described with respect to ablation of tissue in a cardiac chamber of a patient as part of an ablation therapy associated with the treatment of a cardiac arrhythmia. However, it should be understood that, unless otherwise indicated, the systems and methods of the present disclosure may be used in any of a variety of different medical procedures, such as steps performed on a hollow anatomical structure of a patient, where ablation of tissue is part of the medical treatment.

[0171] As used herein, the term "physician" should be taken to include any type of medical personnel who may be performing or assisting in a medical procedure.

[0172] As used herein, the term "patient" should be taken to include any mammal, including humans, on which a medical procedure is performed.

[0173] Figure 1 is a schematic diagram of an ablation system 100 during a cardiac ablation treatment performed on a patient 102. The ablation system 100 includes a catheter 104 connected to a catheter interface unit 108 via an extension cable 106. The catheter interface unit 108 may be a computing device that includes a processing unit 109a, a non-transitory computer-readable storage medium 109b, and a graphical user interface 110. Unless otherwise specified or clear from the context, the processing unit 109a may be a controller including one or more processors, and the storage medium 109b may have computer-executable instructions stored thereon for causing the one or more processors of the processing unit 109a to perform one or more portions of the various methods described herein.

[0174] A mapping system 112, a recording system 111, an irrigation pump 114, and a generator 116 can be connected to the catheter interface unit 108. The irrigation pump 114 can be removably and fluidly connected to the ablation catheter 104 via a fluid line 115. The generator 116 can also, or alternatively, be connected to one or more return electrodes 118 attached to the skin of the patient 102 via one or more of the wires 117. The recording system 111 can be used throughout the ablation treatment and before or after the treatment. The mapping system 112 can be used before and / or during the ablation treatment to map the cardiac tissue of the patient 102 and determine which area or areas of the cardiac tissue need to be ablated.

[0175] Reference now Figure 2-4, the catheter 104 may include a handle 120, a catheter shaft 122, an ablation electrode 124, a sensor 126, and an irrigation element 128. The handle 120 is coupled to a proximal portion 130 of the catheter shaft 122, and a distal portion 132 of the catheter shaft 122 may be coupled to the irrigation element 128 and the ablation electrode 124, which in some embodiments supports the sensor 126. The handle 120 may further, or alternatively, be coupled to one or more of a fluid line 115 and a wire 117 for delivering irrigation fluid and electrical energy to the ablation electrode 124 along the catheter shaft 122, respectively.

[0176] As described in further detail below, in the deployed state of the ablation electrode 124, irrigation liquid exits an irrigation hole 134 defined by the irrigation element 128 and is directed toward an inner portion 136 of the ablation electrode 124 while an outer portion 138 of the ablation electrode 124 (opposite the inner portion 136) contacts tissue as part of an ablation treatment. The spacing between the irrigation hole 134 and the inner portion 136 of the ablation electrode 124 can promote heat transfer between the irrigation liquid and the ablation electrode 124. For example, at the spacing between the irrigation hole 134 and the inner portion 136 of the ablation electrode 124, a jet of irrigation liquid can generate turbulent characteristics. Without wishing to be bound by any theory, it is believed that the increased turbulence can improve local heat transfer from the ablation electrode 124 (e.g., from the inner portion 136 of the ablation electrode 124) compared to a non-turbulent or less turbulent irrigation liquid flow. Additionally, or alternatively, blood can flow through the space between the irrigation port 134 and the inner portion 136 of the ablation electrode 124. Blood flow through the space between the irrigation port 134 and the inner portion 136 of the ablation electrode 124 can additionally, or alternatively, further improve local heat transfer from the outer portion 138 of the ablation electrode 124 compared to a configuration in which blood flow can be blocked from leaving the treatment site. Generally, it should be understood that such improved local heat transfer can reduce the likelihood of blood clotting or charring. As used herein, the term "holes" should be understood to include discrete openings of any size and shape having a maximum dimension through which fluid can flow, and thus should be understood to include any manner and form of generally geometric shapes (e.g., generally circular shapes) and, unless otherwise specified or clear from the context, also or alternatively include generally irregular shapes.

[0177] As further described in detail below, the ablation electrode 124 may include a coupling portion 140 and a deformable portion 142. As used herein, the terms "expandable" and "deformable" are used interchangeably unless otherwise specified or clear from the context. For example, it should be understood that the deformable portion 142 is expandable unless otherwise specified.

[0178] The coupling portion 140 is fixed to the distal portion 132 of the catheter shaft 122, and the deformable portion 142 can extend distally from the coupling portion 140. The deformable portion 142 of the ablation electrode 142 can be deformed for delivery (e.g., through an introducer sheath, such as an 8F introducer sheath) and expanded at the treatment site to have a cross-sectional dimension that is larger than the cross-sectional dimension of the catheter shaft 122. Compared to smaller ablation electrodes, the ablation electrode 124 can provide wider lesions in a shorter period of time, thereby facilitating the generation of a pattern of overlapping lesions (e.g., reducing the likelihood of arrhythmogenic gaps, or reducing the time and number of lesions required for overlapping patterns, or both). Additionally, or alternatively, a larger tip can facilitate the delivery of more power to provide wider and deeper lesions.

[0179] In addition, in the expanded state, the deformable portion 142 of the ablation electrode 124 is deformable based on a force sufficient to contact the tissue, and the shape and degree of deformation can be detected, at least in part, based on a signal received from a sensor 126 on the deformable portion 142 of the ablation electrode 124. As described in detail below, the sensor 126 can be used in one or more parameter measurement modes and, for example, can include one or more of an electrode, a thermistor, an ultrasonic transducer, and an optical fiber. Additionally, or alternatively, the deformable portion 142 can be radiopaque so that the deformation of the deformable portion 142 caused by contact with the tissue can be observed, for example, by X-ray or similar visualization techniques. Detecting and / or observing the deformation of the deformable portion 142 of the ablation electrode 124 can, for example, provide better certainty that the desired treatment is actually provided to the tissue. It should be understood that better certainty in the positioning of the ablation electrode relative to the tissue can reduce the possibility of gaps in the resulting lesion pattern and, also or alternatively, can reduce the time and number of ablations required to eliminate gaps in the resulting lesion pattern.

[0180] The handle 120 may include a housing 145 and a drive portion 146. In use, the drive portion 146 may be operated to deflect the distal portion 132 of the catheter shaft 122 so as to position the ablation electrode 124 in contact with tissue at the treatment site. The handle 120 may include a fluid line connector 148 (e.g., a luer connector) and an electrical connector 149. The fluid line 115 may be connected to the fluid line connector 148, and in use, an irrigation liquid (e.g., saline) may be delivered from the irrigation pump 114 to the catheter 104, as described in further detail below, and the irrigation liquid may ultimately be delivered to the inner portion 136 of the ablation electrode 124 in the catheter 104 through the irrigation port 134 of the irrigation element 128. The extension cable 106 may be connected to the electrical connector 149. In use, electrical energy may be delivered from the generator 116 to the catheter 104 , where it may ultimately be delivered to the ablation electrode 124 to ablate tissue in contact with the outer portion 138 of the ablation electrode 124 , as described in further detail below.

[0181] The handle 120 may be attached to the proximal portion 130 of the catheter shaft 122 by any of a variety of techniques, including one or more of adhesive bonding, thermal bonding, and mechanical attachment.

[0182] The catheter shaft 122 defines a lumen 151 extending from the proximal end portion 130 of the catheter shaft 122 to the distal end portion 132 of the catheter shaft 122. The lumen 151 can be in fluid communication with the irrigation pump 114 via the fluid line 115 and the fluid line connector 148 of the handle 120, so that irrigation liquid can be pumped from the irrigation pump 114 to the irrigation port 134 defined by the irrigation element 128. The catheter shaft 122 can also, or alternatively, include a guide wire (such as a guide wire) extending along the catheter shaft 122. Figure 1 any one or more of the wires 117 shown in ) to transmit signals between the sensor 126 and the catheter interface unit 108 and to transmit electrical energy from the generator 116 to the ablation electrode 124.

[0183] The catheter shaft 122 may be formed from any of a variety of different biocompatible materials that provide the catheter shaft 122 with sufficient strength and flexibility to allow the catheter shaft 122 to be manipulated through a patient's vasculature. Examples of suitable materials from which the catheter shaft 122 may be formed include polyether block amides (e.g., available from Arkema of Colombes, France). ), nylon, polyurethane, (available from The Lubrizol Corporation of Wickliffe, Ohio), and silicone. In certain embodiments, the catheter shaft 122 includes a plurality of different materials along its length. For example, the material can be selected to provide increased flexibility to the catheter shaft 122 at the distal end when compared to the proximal end. The catheter shaft 122 can also, or alternatively, include a tubular braid element that provides torsional stiffness while maintaining bending flexibility to one or more regions of the catheter shaft 122. Further, or alternatively, the shaft material can include a radiopaque agent (e.g., barium sulfate or bismuth) to facilitate fluoroscopic visualization.

[0184] The catheter shaft 122 can also include pull wires (not shown) that are mechanically coupled (e.g., via a ring fixed to the catheter shaft 122) to the distal portion 132 of the catheter shaft 122 and mechanically coupled to the drive portion 146 of the handle 120 as is known in the art. During use, tension can be applied to the wires to deflect the distal portion 132 of the catheter shaft 122 to steer the catheter shaft 122 toward a treatment site.

[0185] The irrigation element 128 may include a stem 154 and a bulb 156. The stem 154 may be coupled to the distal end portion 132 of the catheter shaft 122, in fluid communication with the lumen 151 of the catheter shaft 122 and, ultimately, in fluid communication with the irrigation pump 114. The bulb 156 defines an irrigation port 134 and is in fluid communication with the stem 154. Thus, irrigation liquid may pass through the lumen 151, through the stem 154, and may exit the irrigation element 128 through the irrigation port 134 defined by the bulb 156.

[0186] The stem 154 is generally rigid and extends from the distal portion 132 of the catheter shaft 122 in a direction having a distal component and / or a radial component. For example, the radial extent of the stem 154 can direct irrigation liquid from an eccentric location of the lumen 151 to a location along a central axis defined by the catheter shaft 122. Additionally, or alternatively, the distal extent of the stem 154 can facilitate clearance of the catheter shaft 122 such that a portion of the irrigation port 134 directed in a proximal direction has a generally unobstructed passage to a portion of the interior portion 136 of the ablation electrode 124 proximate the irrigation element 128. Thus, more generally, it should be appreciated that the size and shape of one or more of the stem 154, the bulb 156, and the irrigation port 134 can be varied to achieve a desired directionality of irrigation liquid toward the interior portion 136 of the ablation electrode 124.

[0187] The bulb 156 is generally rigid and, in certain embodiments, is formed of the same material as the shaft 154. Additionally, or alternatively, the bulb 156 is generally spherical to facilitate directing irrigation liquid toward substantially the entire interior portion 136 of the ablation electrode 124. However, it should be understood that the bulb 156 can be any of a variety of different shapes that facilitate dispersion of irrigation liquid toward multiple directions of the interior portion 136 of the ablation electrode 124.

[0188] In some embodiments, the irrigation ports 134 can be spaced circumferentially and axially along the irrigation element. For example, the irrigation ports 134 can be spatially distributed along the bulb 156, wherein at least a portion of the irrigation ports 134 are arranged to direct irrigation liquid in a distal direction relative to the ablation electrode 124, and at least a portion of the irrigation ports 134 are arranged to direct irrigation liquid in a proximal direction relative to the ablation electrode 124. More generally, the irrigation ports 134 can be distributed along the inner portion 136 of the ablation electrode 124 coated with the irrigation element 128 to produce a relatively evenly dispersed irrigation liquid.

[0189] The total radial extent of the irrigation element 128 can be less than the outer diameter of the catheter shaft 122. For example, the irrigation element 128 can maintain the same orientation in the delivery configuration of the catheter 104 for treatment and during treatment at the treatment site, while, as described in further detail below, the ablation electrode 124 expands from a compressed state during delivery to an expanded state during treatment at the treatment site. As also described in further detail below, the fixed orientation of the irrigation element 128 can facilitate the use of the irrigation element 128 as a sensor or carrying a sensor. For example, a sensor can be added to the irrigation element 128 to be used as a sensor in cooperation with the sensor 126, so that the sensor on the irrigation element 128 can be used as a central electrode and the sensor 126 can be used as a surface electrode, as described in more detail below.

[0190] Although the irrigation element 128 can extend distally of the catheter shaft 122, the distal extent of the irrigation element 128 can be limited by the inner portion 136 of the ablation electrode 124. For example, the irrigation element 128 can be spaced relative to the inner portion 136 of the ablation electrode 124 such that the irrigation ports 134 direct irrigation liquid toward the inner portion 136 of the ablation electrode 124 in the expanded state. In particular, assuming that the deformable portion 142 of the ablation electrode 124 is intended to contact tissue during ablation, the irrigation ports 134 can be oriented toward the deformable portion 142 of the ablation electrode 124 to direct fluid toward the inner portion 136 of the ablation electrode 124 along the deformable portion 142 in contact with tissue. Directing irrigation liquid toward the deformable portion 142 of the ablation electrode 124 in this manner can, for example, reduce the likelihood of unintended tissue damage caused by the ablation treatment.

[0191] Now refer to Figure 5 , a schematic diagram of a jet 158 ​​of irrigation liquid leaving one of the irrigation ports 134 and moving toward the inner portion 136 of the ablation electrode 124 just prior to the impact between the jet 158 ​​and the inner portion 136. When the ablation electrode 124 is in an undeformed state (e.g., in the absence of an external force applied to the ablation electrode 124), the distance "L" is the vertical distance between the irrigation port 134 and the inner portion 136 of the ablation electrode 124. For clarity, a two-dimensional cross-section of a single jet is shown. However, it should be understood that in use, the corresponding three-dimensional jets and multiple jets emitted from each irrigation port 134 may interact with each other and / or with the patient's blood along the distance "L" to generate additional turbulence at the inner portion 136 of the ablation electrode 124.

[0192] In embodiments where the irrigation ports 134 have circular cross-sections, the ratio of the maximum dimension "D" of each irrigation port 134 and the corresponding distance "L" between the corresponding irrigation port 134 and the inner portion 136 of the ablation electrode 124 is greater than about 0.02 and less than about 0.2 (e.g., greater than about 0.03 and less than about 0.06). This range of ratios may result in turbulent flow of irrigation liquid at the inner portion 136 of the ablation electrode 124, taking into account other design factors (e.g., manufacturability of the hole size of the irrigation ports 134, acceptable pressure drop for the system, the effect of blood flow between the irrigation element 128 and the ablation electrode 124, or a combination thereof). Without wishing to be bound by any theory, it is believed that the turbulent flow of irrigation liquid moving from the irrigation ports 134 to the inner portion 136 of the ablation electrode 124 may increase heat transfer, which may reduce unintended tissue damage during ablation, compared to configurations having laminar and / or less turbulent flow of irrigation liquid through the inner portion 136 of the ablation electrode 124.

[0193] The size and number of irrigation ports 134 defined by irrigation element 128 are selected so that the pressure of irrigation liquid in irrigation element 128 is sufficient to prevent blood from entering irrigation ports 134. For example, to provide some margin for variation in the pressure of irrigation liquid, the size and number of irrigation ports 134 defined by irrigation element 128 can be selected so that the pressure of irrigation liquid in irrigation element 128 is at least about 0.5 psi greater than the pressure of blood of patient 102. Furthermore, in embodiments where irrigation element 128 is expandable (e.g., a balloon), a positive pressure differential between irrigation liquid within irrigation element 128 and blood of patient 102 can allow irrigation element 128 to maintain an expanded shape. Additionally, or alternatively, the size and number of irrigation ports 134 are selected to provide a substantially uniform coverage of irrigation liquid over deformable portion 142 of ablation electrode 124.

[0194] In certain embodiments, the irrigation opening 134 defined by the irrigation element 128 has a diameter greater than about 0.05 mm. 2 and less than about 0.5 mm 2 In some embodiments, the total number of irrigation ports 134 can be greater than about 50 and less than about 250 (e.g., about 200). In embodiments where the irrigation element 128 is substantially rigid (e.g., formed of stainless steel and / or platinum iridium), the irrigation ports 134 can be formed in the irrigation element 128 using any one or more material removal techniques known in the art, examples of which include drilling and using a laser. In embodiments where the irrigation element 127 is formed of an elastomer, the irrigation ports 134 can be formed by using a laser.

[0195] Reference now Figure 1-11 The ablation electrode 124 is a continuous structure. Figure 1 The ablation system 100 is shown as being used as one electrode in a monopolar electrode configuration. However, it should be understood that the ablation electrode 124 may include electrically isolated portions such that the ablation electrode 124 includes two electrodes of a bipolar electrode configuration.

[0196] The ablation electrode 124 may have an outer diameter greater than about 4 mm and less than about 16 mm (e.g., about 8 mm), and, additionally or alternatively, a thickness greater than about 0.07 mm and less than about 0.25 mm (e.g., about 0.17 mm). In certain embodiments, the ablation electrode 124 may have an open area greater than about 50% and less than about 95% (e.g., about 80% open area). As used herein, the percentage of the open area of ​​the ablation electrode 124 should be understood as the ratio of the area through which fluid can flow from the outer portion 138 of the ablation electrode 124 to the surface area of ​​the convex shell, which includes the outer portion 138 of the ablation electrode 124 and the structural elements that define the outer portion 138 of the ablation electrode, the ratio being expressed as a percentage. It should be understood that the open area of ​​the ablation electrode 124 can facilitate the flow of irrigation fluid and blood through the ablation electrode 124 during treatment. Compared to an ablation electrode that obstructs blood flow, the open area of ​​the ablation electrode 124 can reduce the likelihood of localized heating of the blood at the treatment site when ablation energy is delivered to the tissue. It should be appreciated that delivering irrigation liquid to the interior portion 136 of the ablation electrode 124 can increase the cooling produced by blood flow through the open area alone.

[0197] In general, it should be understood that the dimensions of the ablation electrode 124, including dimensions related to diameter, thickness, and / or opening area, can facilitate retraction of the ablation electrode 124. That is, the force required to retract the ablation electrode 124 into the sheath (e.g., at the end of a procedure) allows the ablation electrode 124 to be retracted by the physician without the assistance of a separate mechanism to provide a mechanical advantage. Further, or alternatively, the dimensions of the ablation electrode 124 can facilitate sufficient expansion of the electrode 124. For example, in the case where the electrode 124 is formed of nitinol, the dimensions of the ablation electrode 124 can be designed so that the strain in the ablation electrode 124 is less than about ten percent in a compressed state (e.g., for delivery). As a more general example, the dimensions of the ablation electrode 124 can be designed so that the ablation electrode 124 can be compressed to a size suitable for delivery (e.g., through an 8 French sheath) by using a force that avoids or at least limits plastic deformation of the material of the ablation electrode 124. It will be appreciated that avoiding or at least limiting plastic deformation in this manner may facilitate expansion of the ablation electrode 124 in a predictable manner (eg, to a full extent) in the absence of applied external forces.

[0198] The coupling portion 140 of the ablation electrode 124 can be directly or indirectly mechanically coupled to the catheter shaft 122. For example, the coupling portion 140 may include struts 144a that are directly coupled to the catheter shaft 122 or coupled to a transition portion that is coupled to the catheter shaft 122. Each strut 144a may include a portion extending parallel to the catheter shaft 122, and the coupling portion 140 is coupled to the catheter shaft 122 along the portion of the strut 144a that extends parallel to the catheter shaft 122. Alternatively, or in addition, the coupling portion 140 may include a complete ring that is directly or indirectly mechanically coupled to the catheter shaft 122.

[0199] The coupling portion 140 can be connected via the wire 117 ( Figure 1 140) and / or electrically coupled to the generator 116 via other conductive paths extending from the generator 116 to the coupling portion 140 along the length of the catheter shaft 122. For example, the coupling portion 140 can be assembled into the distal portion 132 of the catheter shaft 122, connected to the wires extending to the generator 116, and encased in an adhesive in the distal portion 132 of the catheter shaft 122. In use, electrical energy provided at the generator 116 can be delivered to the coupling portion 140, and therefore, to the deformable portion 142 of the ablation electrode 124, where the electrical energy can be delivered to tissue of the patient 102.

[0200] The deformable portion 142 of the ablation electrode 124 may include struts 144b that are mechanically coupled to each other at the connection points 141a to collectively define a plurality of holes 147 of the ablation electrode 124. Additionally, or alternatively, the struts 144b may be mechanically coupled to each other via fasteners 141b. Thus, each end of a strut 144b may be coupled to an end of another strut 144b, to a fastener 141b, or a combination thereof to define the deformable portion 142 of the ablation electrode 124. For example, the struts 144b along the deformable portion 142 of the ablation electrode may be coupled to each other, to a fastener 141b, or a combination thereof to define a closed shape along the deformable portion 142. Additionally, or alternatively, at least some of the struts 144b may be coupled to struts 144a to transition between the deformable portion 142 and the coupled portion 140 of the ablation electrode 124. In certain embodiments, strut 144b can be coupled to strut 144a such that coupling portion 140 defines an open shape along coupling portion 140 to facilitate securing strut 144a to distal portion 132 of catheter shaft 122, for example.

[0201] The catheter shaft 122 defines a central axis CL-CL extending from the proximal portion 130 to the distal portion 132 of the catheter shaft 122. The holes 147 can have a generally axial orientation relative to the central axis CL-CL. For example, each hole 147 can have a corresponding plane of symmetry passing through the distal end of the hole 147, the proximal end of the hole 147, and the central axis CL-CL. This orientation can advantageously preferentially expand and contract the hole 147 relative to the central axis CL-CL, which can help compress the deformable portion 142 of the ablation electrode 124 to a size suitable for delivery to the treatment site.

[0202] For example, in the absence of external forces applied to the ablation electrode, the central axis CL-CL can extend through the fastener 141b. In some cases, such alignment of the fastener 141b can facilitate positioning of the distal portion 142 of the ablation electrode 124 (eg, by positioning the fastener 141b at a treatment site).

[0203] The fastener 141b can be formed of a first material (e.g., a polymer) and the strut 144b can be formed of a second material different from the first material (e.g., nitinol). It should be understood that the material of the fastener 141b can be selected to be suitable for maintaining the struts 144b coupled to each other while achieving a combination of strength and electrical properties that is suitable for a current density distribution for a particular application. For example, the closed shape of the deformable portion 142 can help deliver a substantially uniform current density through the ablation electrode 124 in a manner that is less dependent on the orientation of the ablation electrode 124 relative to the tissue, as described in more detail below, as compared to an electrode having an open shape.

[0204] Typically, each aperture 147 may be defined by at least three struts 144b. Additionally, or alternatively, each strut 144b may define a portion of at least two apertures 147. The inner portion 136 of the ablation electrode 124 may be in fluid communication with the outer portion 138 of the ablation electrode 124 through the plurality of apertures 147, such that, in use, irrigation fluid, blood, or a combination thereof may move through the plurality of apertures 147 to cool the ablation electrode 124 and tissue adjacent to the ablation electrode 124.

[0205] At least some of the plurality of holes 147 can be flexible in the axial and lateral directions such that the open frame formed by the plurality of holes 147 along the deformable portion 142 of the ablation electrode 124 is equally flexible. For example, at least some of the plurality of holes can be substantially diamond-shaped in an uncompressed state of the deformable portion 142 of the ablation electrode 124. As used herein, a substantially diamond-shaped shape includes a shape having a first pair of connection points substantially aligned along a first axis and a second pair of connection points substantially aligned along a second axis, wherein the second axis is different from the first axis (e.g., perpendicular to the first axis).

[0206] The flexibility of the open frame formed by the plurality of holes 147 along the deformable portion 142 of the ablation electrode 124 can, for example, advantageously resist movement of the deformable portion 142 in contact with tissue during a medical procedure. That is, the deformable portion 142 can deform when in contact with tissue, and the deformable portion 142 can engage the tissue through one or more of the holes 147 to resist lateral movement of the deformable portion 142 relative to the tissue. That is, the deformable portion 142 will resist unintended movement (e.g., sliding relative to the tissue) in contact with it compared to a closed surface in contact with tissue. It should be appreciated that such resistance to movement can contribute to, for example, more accurate lesion placement.

[0207] The dimensions of the struts 144a, 144b can be different from the corresponding dimensions of the other of the struts 144a, 144b. For example, the strut 144b can have a dimension (e.g., width) that is different from the corresponding dimension of another of the struts 144b. For example, the different dimensions of the struts 144a, 144b can help deliver a substantially uniform current density through the deformable portion 142 of the ablation electrode 124, as described in more detail below. Additionally, or alternatively, the strut 144a can be wider than the strut 144b to facilitate securing the strut 144a directly or indirectly to the distal portion 132 of the catheter shaft 122.

[0208] Typically, the struts 144b can be sized and positioned relative to each other to deliver a substantially uniform current density through the deformable portion 142 of the ablation electrode 124, as described in more detail below. As a non-limiting example, a first group of struts 144b can have a first width and a second group of struts 144b can have a second width different from the first width. Continuing with this example, the first group of struts 144b can be axially spaced relative to the second group of struts 144b. Such axial distribution of strut material can be useful, for example, for achieving a desired current density profile (e.g., a substantially uniform current density profile). As another non-limiting example, at least some of the struts 144b can have a non-uniform width along the length of the respective struts 144b, such that the amount of material along a given strut varies, resulting in a correlated distribution of current density. For example, at least some of the struts 144b can include a width that increases along the length of the respective struts 144b in a direction from a proximal region to a distal region of the ablation electrode 124.

[0209] While the dimensions of the struts 144b may be varied to achieve a desired current density distribution along the deformable portion 142, it should be understood that the current density distribution is more generally characterized as a distribution function of the metal along the deformable portion 142 of the ablation electrode 124. Because the metal of the struts 144b defines a plurality of apertures 147, it should be further understood that the distribution of current density is also related to the open area of ​​the plurality of apertures 147. In particular, maintaining a substantially constant ratio of the open area of ​​the apertures 147 to the volume of the material of the struts 144 that defines the open area of ​​the apertures 147 along each meridian of the deformable portion 142 may serve as a useful design guide for achieving a substantially uniform distribution of current density. However, maintaining this substantially constant ratio must be achieved while also meeting the structural requirements of forming the desired shape of the deformable portion 142. That is, any suitable solution for the arrangement of the struts 144b to form the plurality of holes 147 for producing a substantially uniform current density must also meet the structural requirements for forming the desired shape (eg, a substantially spherical shape) of the deformable portion 142 .

[0210] Generally, a substantially uniform current distribution can be achieved along the generally spherical shape of the deformable portion 142 by varying the pattern of struts 144 and apertures 147 from the proximal region to the distal region of the deformable portion 142. For example, a substantially uniform current distribution can be achieved and meet the structural requirements of the desired shape of the deformable portion 142 by varying one or more of the dimensions (e.g., length, width, and thickness) of the struts 144b, the number of struts 144b, and the number of apertures 147 along the deformable portion 142. Thus, for example, the struts 144b can have a substantially uniform width and / or thickness, while the number of struts 144b and one or more of the number of apertures 147 can vary from the proximal region to the distal region of the deformable portion 142. As an additional, or alternative example, the number of apertures 147 along a meridian of one or both of the distal and proximal regions of the deformable portion 142 can be less than the number of apertures 147 along a meridian passing through the maximum radial dimension of the ablation electrode.

[0211] In general, the plurality of holes 147 can be disposed circumferentially and axially around the ablation electrode 124. More specifically, as described in more detail below, the plurality of holes 147 can be arranged around the ablation electrode 124 (e.g., along the deformable portion 142 of the ablation electrode 124) to facilitate contraction and expansion of the deformable portion 142 and / or to facilitate a generally uniform distribution of current density along the deformable portion 142.

[0212] Each hole 147 can be defined. In particular, as used herein, a defined hole 147 includes a hole that is completely defined by a support 144b, a connection point 141a, a sensor 126 disposed along a support 144b or a connection point 141a, or a combination thereof. As described in further detail below, the support 144b can be connected to each other at the connection point 141a as part of a unified structure or a substantially unified overall structure. Additionally, or alternatively, as described in more detail below, the support 144b can be connected to each other by welding, fasteners, or other mechanical connections at one or more connection points 141a.

[0213] The struts 144b can move relative to each other by bending at the connection points 141a. More specifically, the struts 144b can be flexible relative to each other to allow the deformable portion 142 to move between a compressed state in the presence of an external force and an uncompressed state in the absence of an external force. For example, when the coupled struts 144b move relative to each other to allow the ablation electrode 124 to transition from a compressed state in the presence of an external force to an uncompressed state in the absence of an external force, the maximum radial dimension (or referred to herein as the lateral dimension) of the ablation electrode can be increased by at least two times. This size increase ratio is achieved by using an open frame 147 formed by the struts 144b, which allows less material to be used than would be required for a solid shape of the same size. Further, or alternatively, it should be understood that the size increase ratio achieved by using an open frame of holes 147 is useful for delivery to a treatment site through an 8 French sheath, while also promoting the formation of a large lesion at the treatment site.

[0214] By bending at the connection point 141a and the associated movement of the strut 144b, the deformable portion 142 can be elastically compliant in the axial direction relative to the catheter shaft 122 and / or in the radial direction relative to the catheter shaft 122. Additionally, or alternatively, the deformable portion 142 can expand (e.g., self-expand) from a compressed state to an uncompressed state. For example, the struts 144b can be biased to move away from each other in one or more directions so that the deformable portion 142 self-expands from a compressed state to an uncompressed state. In some cases, the inner portion 136 of the ablation electrode 124 along the deformable portion 142 can be closer to at least a portion of the surface of the irrigation element 128 in the compressed state than in the uncompressed state, and therefore, when the deformable portion 142 expands from the compressed state to the uncompressed state, the inner portion 136 of the ablation electrode 124 can move away from at least a portion of the surface of the irrigation element 128. In some cases, the inner portion 136 of the ablation electrode 124 along the deformable portion 142 may be closer to at least a portion of the surface of the irrigation element 128 in a compressed state than in an uncompressed state, and therefore, when the deformable portion 142 expands from a compressed state to an uncompressed state, the inner portion 136 of the ablation electrode 124 may move away from at least a portion of the surface of the irrigation element 128.

[0215] In an uncompressed state, the struts 144b, the connection points 141a, and the apertures 147 can together form an open frame having a conductive surface along the deformable portion 142 of the ablation electrode 124. For example, when the deformable portion 142 of the ablation electrode 124 is in an uncompressed state, the open frame formed by the struts 144b, the connection points 141a, and the apertures 147 can have an open area greater than about 50% along the outer portion 138 of the ablation electrode 124. Continuing with this example, in the uncompressed state, the combined open area of ​​the apertures 147 can be greater than the combined area of ​​the struts 144b and the connection points 141a along the outer portion 138 of the ablation electrode 124. Further, or alternatively, at least some of the apertures 147 have a larger area in the uncompressed state of the deformable portion 142 than in the compressed state of the deformable portion 142.

[0216] More generally, when the deformable portion 142 is collapsed from an uncompressed state to a compressed state, the open area defined by the apertures 147 can be of a size and spatial distribution sufficient to accommodate the struts 144b and, optionally, the sensors 126. Thus, it should be appreciated that the size of the ratio of the combined open area of ​​the apertures 147 to the combined area of ​​the struts 144b and the connection points 141a can be used, among other things, to change the degree of expansion of the deformable portion 142 of the ablation electrode 124 relative to a delivery state in which the deformable portion 142 is in a compressed state. That is, the ratio of the combined open area of ​​the apertures 147 to the combined area of ​​the struts 144b and the connection points 141a can facilitate minimally invasive delivery of the ablation electrode 124 (e.g., delivery through an 8 Fr sheath).

[0217] As an example, when the struts 144b move relative to each other to transition the ablation electrode 124 (e.g., the deformable portion 142 of the ablation electrode 124) from a compressed state in the presence of an external force (e.g., a radial force) to an uncompressed state in the absence of the external force, the maximum radial dimension of the ablation electrode 124 can be increased by at least 2 times. Additionally, or alternatively, the struts 144b can move relative to each other such that the maximum radial dimension of the deformable portion 142 in the uncompressed state is at least about 20% greater than the maximum radial dimension of the catheter shaft 122 (e.g., greater than the maximum radial dimension of the distal portion 132 of the catheter shaft 122). It should be understood that the extension of the deformable portion 142 beyond the maximum radial dimension of the catheter shaft 122 can help create a lesion having a large width compared to an ablation electrode constrained by the radial dimension of the catheter shaft.

[0218] In some embodiments, the ablation electrode 124 has a maximum axial dimension that changes by less than about 33% (e.g., about 20%) when the outer portion of the radial force applied to the ablation electrode 124 is removed to allow the struts 144b to expand (e.g., self-expand) from an uncompressed state to a compressed state.

[0219] At least some of the struts 144b extend in a direction having a circumferential dimensional component relative to an axis defined by the catheter shaft 122 (e.g., an axis defined by the proximal portion 130 and the distal portion 132 of the catheter shaft 122). That is, the struts 144b extending in a direction having a circumferential dimensional component relative to the axis defined by the catheter shaft 122 are not parallel to the axis defined by the catheter shaft 122. In some embodiments, at least some of the struts 144b include a non-uniform width along the length of each strut 144b. Because the current density at a given point along the ablation electrode 124 is a function of the amount of surface area at a given point along the ablation electrode 124, the non-uniform width of a given one of the struts 144b can help balance the current density to achieve a target current density distribution along the deformable portion 142 of the ablation electrode 124. As described in more detail below, the circumferential extension and / or the non-uniform width along the length of at least some of the struts 144b can facilitate a substantially uniform distribution of current density along the deformable portion 142 during a medical procedure.

[0220] While the large surface area of ​​the struts 144b is advantageous for delivering energy to tissue, the upper boundary of the area of ​​the struts 144b can be a geometric configuration that allows the struts 144b to fold into a compressed state (e.g., during delivery to a treatment site and / or during contact with tissue at a treatment site) without interfering with each other. Additionally, or alternatively, the struts 144b can be twisted toward the inner portion 136 of the ablation electrode 124. It should be understood that the twisted struts 144b can be wider than untwisted struts while still being able to fold into a compressed state without interfering with each other. Additionally, or further alternatively, the upper boundary of the area of ​​the struts 144b can be the amount of open area of ​​the deformable portion 142, which will promote proper heat transfer at the ablation electrode 124 (e.g., during ablation) via the movement of flushing fluid and / or blood through the deformable portion 142.

[0221] As used herein, the uncompressed state of the deformable portion 142 refers to the state of the deformable portion 142 in the absence of a significant applied force (e.g., an applied force less than about 5 grams). Thus, the uncompressed state of the deformable portion 142 includes the state of the ablation electrode 124 in the absence of an external force. Additionally, the uncompressed state of the deformable portion 142 includes the state of the ablation electrode 124 in which a small applied force (e.g., less than about 5 grams) is present, but not sufficient to produce a significant deformation in the deformable portion 142.

[0222] In the uncompressed state of the deformable portion 142, the ablation electrode 124 can be bulbous. For example, in the uncompressed state, the deformable portion 142 can be a shape having symmetry in the radial direction and / or the axial direction relative to the catheter shaft 122. For example, in the uncompressed state, the deformable portion 142 can be an ellipsoidal shape, for example, a generally spherical shape (e.g., an arrangement of struts 144b, each strut 144b having a planar shape that approximates a spherical shape relative to each other). Additionally, or alternatively, in the uncompressed state, the deformable portion 142 can be a symmetrical shape (e.g., a generally ellipsoidal shape or another similar shape included between a first radius and a perpendicular second radius, the first radius and the second radius being within 30% of each other in size). The symmetry of the deformable portion 142 can, for example, help to uniformly deliver ablation energy to the tissue in multiple orientations of the deformable portion 142 relative to the tissue being ablated.

[0223] At least when the deformable portion 142 is in an uncompressed state, the deformable portion 142 can envelop the irrigation element 128 such that the irrigation element 128 directs irrigation liquid toward the interior portion 136 of the ablation electrode 124. Thus, in embodiments where the deformable portion 142 is symmetrical, the irrigation element 128 can provide a substantially even distribution of irrigation liquid along the interior portion 136 of the ablation electrode 124 because the deformable portion 142 in the uncompressed state envelops the irrigation element 128.

[0224] In some embodiments, the maximum cross-sectional dimension of the deformable portion 142 in the uncompressed state is greater than the maximum cross-sectional dimension of the catheter shaft 122. Thus, because the deformable portion 142 is expandable to extend beyond the catheter shaft 122, the deformable portion 142 can produce a lesion that is greater than the maximum dimension of the catheter shaft 122, such that the produced lesion is wider and deeper than the lesion produced by the non-expanded ablation electrode. For example, in the uncompressed state, the deformable portion 142 can be generally circular at the maximum cross-sectional dimension of the deformable portion, and the catheter shaft 122 can be generally circular at the maximum cross-sectional dimension of the catheter shaft 122. Thus, continuing with this example, the outer diameter of the deformable portion 142 is greater than the outer diameter of the catheter shaft 122.

[0225] As used herein, a compressed state of the ablation electrode 124 refers to a state of the ablation electrode in the presence of a force (e.g., about 5 grams or greater) sufficient to cause the deformable portion 142 to bend (e.g., by bending one or more of the connection points 141a) to a significant degree. Thus, for example, the compressed state of the ablation electrode 124 includes a reduced size profile of the ablation electrode 124 during introduction of the catheter 104 to the treatment site, as described in further detail below. The compressed state of the ablation electrode 124 also includes one or more deformations and / or partial deformations caused by external forces applied along one or more portions of the deformable portion 142 of the ablation electrode 124 due to contact between the deformable portion 142 and tissue at the treatment site.

[0226] The compression state of the ablation electrode 124 may have a predetermined relationship with respect to the applied force. For example, the compression state of the ablation electrode 124 may have a substantially linear (e.g., within ±10%) relationship with the force applied within the range of forces typically applied during the ablation procedure (e.g., a deformation of approximately 1 mm in response to a force of 60 grams). It should be understood that such a predetermined relationship is useful, for example, for determining the magnitude of the force applied on the ablation electrode 124 based on the measured amount of deformation of the ablation electrode 124. That is, given a predetermined relationship between the deformation of the ablation electrode 124 and the magnitude of the applied force, determining the amount of deformation of the ablation electrode 124 may provide an indication of the magnitude of the force being applied by the ablation electrode 124 on the tissue at the treatment site. Similarly, the determined amount of deformation of the ablation electrode 124 may be used, for example, as feedback to control the magnitude of the force applied to the tissue at the treatment site. Methods for determining the amount of deformation of the ablation electrode 124 are described in more detail below.

[0227] Fig. 9 is a graph of an exemplary relationship between displacement and force for different magnitudes of force applied to the deformable portion 142 of the ablation electrode 124. The deformable portion 142 of the ablation electrode 124 may have different force-displacement responses depending on the direction of the force applied to the deformable portion 142 of the ablation electrode 124. For example, Fig. 9 As shown in the exemplary relationship in FIG. 1 , the deformable portion 142 of the ablation electrode 124 may have an axial force-displacement response 143a and a lateral force-displacement response 143b. That is, the response of the deformable portion 142 to the applied force may depend on the direction of the applied force. Fig. 9 In the specific example of FIG. 1 , the deformable portion 142 is more rigid in the axial direction than in the lateral direction.

[0228] In general, the axial force-displacement 143a and the lateral force-displacement responses 143b can be reproducible, and therefore, the magnitude of the force applied to the deformable portion 142 of the ablation electrode 124 in the axial and / or lateral directions can be reliably determined based on the corresponding displacement of the deformable portion 142. Therefore, as described in more detail below, the determined displacement of the deformable portion 142 can be used to determine the magnitude and direction of the force applied to the deformable portion 142. More generally, because the deformable portion 142 can move between a compressed state and an uncompressed state in a reproducible manner in response to an applied force, the deformable portion 142 of the ablation electrode can be used as a contact force sensor, and therefore, can help apply the appropriate force during an ablation treatment.

[0229] In some embodiments, at least a portion of the ablation electrode 124 is radiopaque and the deformable portion 142 is observable using fluoroscopy or other similar visualization techniques. For example, the deformable portion 142 of the ablation electrode 124 can be radiopaque such that fluoroscopy can provide an indication of deformation and / or partial deformation of the deformable portion 142 and, therefore, provide an indication of whether the deformable portion 142 is in contact with tissue.

[0230] The material used to form the ablation electrode 124 may include Nitinol, which has weak radiopacity and has repeatable and reliable flexibility between a compressed state and an uncompressed state. Additionally, or alternatively, the material used to form the ablation electrode 124 may be coated with one or more of gold or tantalum. Thus, continuing with this example, the deformable portion 142 (e.g., the strut 144b) of the ablation electrode 124 may be formed of Nitinol (alone or coated) such that ablation energy is delivered through the Nitinol forming the deformable portion 142 for delivery to tissue to produce damage.

[0231] As described in further detail below, additionally, or alternatively, deformation and / or partial deformation of the deformable portion 142 in compression may be detected by the sensor 126 to provide feedback regarding the extent and direction of contact between the deformable portion 142 of the ablation electrode 124 and tissue at the treatment site.

[0232] Reference now Fig.10 and 11, the sensors 126 can be mounted along the deformable portion 142 of the ablation electrode 124. Each sensor 126 can be electrically insulated from the ablation electrode 124 and mounted on one of the struts 144b of the deformable portion 142. For example, each sensor 126 can be mounted to the deformable portion 142 using a flexible adhesive (e.g., room temperature vulcanizing (RTV) silicone), or any of a variety of different mechanical retaining features (e.g., tabs) between the sensor 126 and the ablation electrode 124 and / or the sensor 126 can be molded or overmolded to the ablation electrode 124. Mounting the sensor 126 on the struts 144b can reduce the physical strain on the sensor 126 compared to mounting the sensor 126 on the deformable portion 142 that experiences greater bending when the deformable portion 142 moves between the compressed and uncompressed states because the struts 144b do not experience significant bending when the deformable portion 142 moves between the compressed and uncompressed states.

[0233] A wire 148 extends from each sensor 126 along the inner portion 136 of the ablation electrode 124 and into the catheter shaft 122 ( Figure 2 ). The guide wire 148 and the catheter interface unit 108 ( Figure 1 ) are electrically connected, as described in further detail below, so that each sensor 126 can send electrical signals to and receive electrical signals from the catheter interface unit 108 during use.

[0234] In general, the sensor 126 can be positioned along one or both of the inner portion 136 and the outer portion 138 of the ablation electrode 124. For example, the sensor 126 can extend through a portion of the ablation electrode 124. Such positioning of the sensor 126 through a portion of the ablation electrode 124 can help form a reliable mechanical connection between the sensor 126 and the ablation electrode 124. Additionally, or alternatively, positioning the sensor 126 through a portion of the ablation electrode 124 can help measure conditions along both the outer portion 138 and the inner portion 136 of the ablation electrode 124.

[0235] When the deformable portion 142 of the ablation electrode 124 is in an uncompressed state, the sensors 126 can be generally evenly spaced apart from one another (e.g., circumferentially and / or axially) along the deformable portion 142 of the ablation electrode 124. Such a generally even distribution of the sensors 126 can, for example, help determine a precise deformation and / or temperature profile of the deformable portion 142 during use.

[0236] Each sensor 126 can be used as an electrode (e.g., a surface electrode) to detect electrical activity of the heart in a localized area of ​​the sensor 126, and further, or alternatively, each sensor 126 can include a flexible printed circuit 150, a thermistor 152 fixed between portions of the flexible printed circuit 150, and a terminal pad 155 opposite the thermistor 152. As an example, the sensor 126 can be mounted on the deformable portion 142 of the ablation electrode 124, the thermistor 152 is disposed along the outer portion 138 of the deformable portion 142, and the terminal pad 155 is disposed along the inner portion 136 of the deformable portion 142. In some cases, the thermistor 152 can be disposed along the outer portion 138 to provide an accurate indication of tissue temperature. A thermally conductive adhesive or other conductive material can be disposed on the thermistor 152 to secure the thermistor 152 to the flexible printed circuit 150.

[0237] In some embodiments, each sensor 126 can include a radiopaque portion and / or radiopaque markings. Adding radiopacity to the sensor 126 can, for example, facilitate visualization of the sensor 126 during use (e.g., using fluoroscopy). Examples of radiopaque materials that can be added to the sensor 126 include: platinum, platinum iridium, gold, radiopaque ink, and combinations thereof. The radiopaque material can be added in any pattern (e.g., dots and / or rings) that can facilitate visualization of the radiopaque material.

[0238] In some embodiments, each sensor 126 can form part of an electrode pair for detecting contact between each sensor 126 and tissue. For example, electrical energy (e.g., current) can be driven through each sensor 126 and another electrode (e.g., any one or more of the various different electrodes described herein), and changes in the measured signal (e.g., voltage or impedance) can indicate the presence of tissue. Because the position of the ablation electrode 124 is known, contact detection through corresponding measurement signals at the sensor 126 can be used to determine the shape of the anatomical structure in which the ablation electrode 124 is disposed during the medical procedure.

[0239] In use, each sensor 126 may further, or alternatively, function as an electrode to detect electrical activity in the local cardiac region of the respective sensor 126, wherein the detected electrical activity forms the basis of an electrogram associated with the respective sensor 126 and further, or alternatively, provides injury feedback. The sensors 126 may be arranged such that the electrical activity detected by each sensor 126 may form the basis of a unipolar electrogram and / or a bipolar electrogram. Additionally, or alternatively, the sensors 126 may be coupled to a central electrode (e.g., an electrode associated with an irrigation element, such as Fig.21 and22 The central electrode 235 in, or the irrigation element itself, e.g. Figure 3 The sensor 126 and the central electrode may cooperate to provide a near-unipolar electrogram, as described in more detail below. It should be understood that the sensor 126 and the central electrode may cooperate to provide a near-unipolar electrogram in addition to, or alternatively to, any one or more of a variety of different methods of determining contact, shape, force, and impedance described herein, each of which may further or alternatively include cooperation between the sensor 126 and the central electrode.

[0240] Figures 12A-12C is a schematic diagram of an exemplary method of manufacturing an ablation electrode 124 from a sheet of material 156 .

[0241] like Fig. 12A As shown, the sheet of material 156 is flat. As used herein, flat material includes materials that exhibit flatness within normal manufacturing tolerances associated with the material. The material of the sheet 156 is conductive and, optionally, also radiopaque. For example, the sheet 156 can be nitinol.

[0242] The thickness of the sheet 156 can correspond to the thickness of the ablation electrode 124. For example, the thickness of the sheet 156 can be greater than about 0.1 mm and less than about 0.20 mm. However, in some embodiments, the thickness of the sheet 156 can be greater than the thickness of at least a portion of the ablation electrode 124, so that removing material from the flat sheet includes removing material in the thickness direction of the sheet 156. For example, material can be selectively removed in the thickness direction of the sheet 156 to produce an ablation electrode 124 having a variable thickness (e.g., an ablation electrode 124 having a variable thickness along the connection point 141a ( Figure 6-8 ) can be thinner to facilitate bending).

[0243] like Fig. 12B As shown, material may be removed from sheet 156 to define the open area of ​​deformable portion 142 and to define coupling portion 140. Specifically, removal of material along deformable portion 142 may define struts 144b and connection points 141a.

[0244] For example, the material of sheet 156 may be removed using any of a variety of different subtractive manufacturing processes. As an example, the material of sheet 156 may be removed using chemical etching (also known as photoetching or photochemical etching) according to any one or more methods known in the art, and generally includes removing the material by selectively exposing the material to an acid. Additionally, or alternatively, the material of sheet 156 may be removed by laser cutting the material. The removal of material may be performed to form openings in sheet 156 and / or to thin selected portions of sheet 156.

[0245] Because the sheet 156 is flat, removing material from the sheet 156 to form the deformable portion 142 can have certain advantages. For example, removing material from the sheet 156 can help control geometric tolerances compared to removing material from a curved workpiece. Additionally, or alternatively, removing material from the sheet 156 can facilitate sensor placement compared to removing material from a curved workpiece (e.g., when the sheet 156 is flat). In some embodiments, removing material from the sheet 156 can reduce or even eliminate the need for shaping the sheet 156 compared to removing material from a curved workpiece because the distal and proximal portions can be put together to form the shape of the ablation electrode 124 (e.g., a generally spherical shape).

[0246] In certain embodiments, the material removed from the sheet 156 can define an eyelet 157 disposed at one end of at least a portion of the struts 144b. The eyelet 157 can, for example, be defined at the intersection of two or more struts 144b.

[0247] In general, the material forming the ablation electrode 124 can be processed at any of a variety of different stages in the manufacture of the ablation electrode 124. For example, material is removed from a sheet to define a portion of the ablation electrode 124. Fig. 12B As shown in the struts 144a, 144b and the connection point 141a, one or more surfaces of the material can be electropolished. For example, such electropolishing can be used to smooth the surface and / or otherwise fine-tune the amount of material along the ablation electrode 124.

[0248] like Fig. 12C As shown, with material removed from sheet 156 to define struts 144a, 144b and connection point 141a, components 158 are bent into proximity with each other and connected to each other to form a unified three-dimensional structure having the overall shape of ablation electrode 124. For example, struts 144b can be bent toward each other, and fasteners 141b can connect portions of struts 144b to each other at eyelets 157, thereby defining a closed distal end of a deformable portion 142 of ablation electrode 124. With the deformable portion 142 defined, fasteners 141b can be located at the most distal portion of the deformable portion 142.

[0249] In some embodiments, the fastener 141b may be a rivet. In such an embodiment, the eyelets 157 may be aligned with each other, for example, so that the fastener 141b passes through the aligned eyelets 157 to hold them together by the force applied by the fastener 141b on the eyelets 157. Additionally, or alternatively, a secondary operation such as welding may secure the fastener 141b to the support 144b at the eyelet 157.

[0250] Reference now Fig.13AAs shown in Figure 1-E, to perform a cardiac ablation treatment, the distal portion 132 of the catheter shaft 122 and, therefore, the ablation electrode 124 can first be introduced into the patient, typically via the femoral vein or artery. Fig.13A -E schematically illustrates a series of steps performed to introduce the ablation electrode 124 into a patient.

[0251] In the first step, if Fig.13A As shown, an introducer sheath 162 is positioned within a blood vessel of a patient (eg, a femoral artery of the patient), and an ablation electrode 124 is positioned for insertion into the introducer sheath 162 .

[0252] In the second step, if Fig. 13B As shown, the user grasps the handle 120 of the catheter 104 and advances the insertion sheath 164 distally along the catheter shaft 122 until the insertion sheath 164 surrounds the ablation electrode 124. As the insertion sheath 164 is advanced over the ablation electrode 124, the ablation electrode 124 collapses to a diameter that can be inserted into the introducer sheath 162.

[0253] In the third step, if Fig. 13C As shown, the user inserts the insertion sheath 164 (containing the ablation electrode 124) into the introducer sheath 162 and advances the catheter 104 distally.

[0254] In the fourth step, if Fig.13D As shown, after the ablation electrode 124 is positioned within the introducer sheath 162, the ablation electrode 124 is pushed out of the insertion sheath 164 and then remains around the proximal portion 130 of the catheter shaft 122 throughout the remainder of the treatment.

[0255] In the fifth step, if Fig.13E As shown, the catheter 104 is advanced through the introducer sheath 162 and the patient's vasculature until the ablation electrode 124 reaches a treatment site in the patient's heart. As the ablation electrode 124 extends distally beyond the introducer sheath 162, the ablation electrode 124 can expand to an uncompressed state.

[0256] Because the ablation electrode 124 is foldable, the introducer sheath 162 can have a small diameter, which can be inserted through a correspondingly small insertion site. Generally, a small insertion site is desirable to reduce the likelihood of infection and / or reduce the amount of time required for healing. In some embodiments, the introducer sheath 162 can have an 8 French diameter, and the deformable portion 142 ( Figure 3) can be folded into a size that can be delivered through such a size of the introducer sheath 162. In some embodiments, the irrigation element 128 can also be folded into a size that is smaller than the size of the ablation electrode 124, so that the irrigation element 128 and the ablation electrode 124 together can be delivered through such a size of the introducer sheath 162.

[0257] Fig.14A -C schematically represents an exemplary method of placing the deformable portion 142 of the ablation electrode 124 in contact with the tissue "T" at the treatment site. It should be understood that since the delivery of ablation energy to the tissue "T" at the treatment site is enhanced by the contact between the ablation electrode 124 and the tissue "T", such contact should be established before delivering the ablation energy.

[0258] In the first step, if Fig.14A As shown, the deformable portion 142 of the ablation electrode 124 is away from the tissue "T" and, therefore, is in an uncompressed state. In some cases, this uncompressed state can be observed through fluoroscopy. That is, the shape of the deformable portion 142 can be observed in the uncompressed state.

[0259] In the second step, if Fig. 14B As shown, the deformable portion 142 of the ablation electrode 124 is initially in contact with the tissue "T". Depending on the nature of the contact between the tissue "T" and the deformable portion 142 of the ablation electrode 124, the deformation of the deformable portion 142 may or may not be observable only through fluoroscopy. For example, the contact force on the deformable portion 142 may not be sufficient to compress the deformable portion 142 to an extent observable using fluoroscopy. Additionally, or alternatively, the contact may not be observable, or may be difficult to observe, in the viewing direction provided by fluoroscopy.

[0260] In the third step, if Fig. 14C As shown, the deformable portion 142 of the ablation electrode 124 is further moved to contact the tissue "T" so that sufficient contact is established between the deformable portion 142 and the tissue "T" to deform the deformable portion 142. Although such deformation can be observed using fluoroscopy, it is not easy to determine the extent and / or direction of the deformation using only fluoroscopy. In addition, as with the initial contact, the contact and / or extent of contact may not be observable, or may be difficult to observe, in the viewing direction provided by the fluoroscopy. Therefore, as described in more detail below, determining the attachment (apposition) of the deformable portion 142 to the tissue "T" may, additionally or alternatively, include detecting the position of the deformable portion 142 based on a signal received from the sensor 126.

[0261] Refer to Figure 1 and3 , the sensor 126 can be used to determine the shape of the deformable portion 142 of the ablation electrode 124, and therefore determine whether and to what extent certain areas of the deformable portion 142 are in contact with the tissue "T". However, it should be understood that the detection methods described herein can be performed using the sensor 126 alone or in combination with another electrode (e.g., an electrode carried on an irrigation element), as described in more detail below.

[0262] For example, the processing unit 109a can control the generator 116 and / or another power source to drive electrical signals between any number and combination of electrode pairs formed by any combination of electrodes associated with the ablation electrode 124, and the processing unit 109a can receive a signal (e.g., a signal indicative of a voltage) from another electrode pair or the same electrode pair. For example, the processing unit 109a can control the generator 116 to drive the sensor 126, the ablation electrode 124, the irrigation element 128, and the central electrode (e.g., Fig.21 and 22 Additionally, or alternatively, multiple pairs may be driven in a multiplexed manner using time division, frequency division, code division, or a combination thereof. The processing unit 109a may also, or alternatively, receive signals from the sensor 126, the ablation electrode 124, the irrigation element 128, and the central electrode (e.g., Fig.21 and 22 One or more of the central electrodes 235 shown in the figure receive one or more measured electrical signals. The driven electrical signal can be any of a variety of different forms, including, for example, a specified current or a specified voltage. In some embodiments, the driven electrical signal is an 8kHz alternating current applied between one of the sensors 126 and the flushing element 128.

[0263] In an exemplary method, when an electrical signal is driven through an electrode pair, an impedance detected by the electrode pair can be detected (e.g., as a signal received by the processing unit 109a). The impedances detected for a plurality of electrode pairs can be compared with each other, and the relative distance between the components of each electrode pair can be determined. For example, if the sensors 126 are identical, each sensor 126 can be driven as part of a corresponding electrode pair including an irrigation element 128. For each such electrode pair, the impedance measured between the electrode pairs can indicate the relative distance between the specific sensor 126 and the irrigation element 128 that form the corresponding electrode pair. In an embodiment where the irrigation element 128 is stationary when the electrical signal is driven through the electrode pair, the relative distance between each sensor 126 and the irrigation element 128 can further indicate the relative distance between each sensor 126 and each other sensor 126. Typically, driven electrodes with lower measured impedances are closer to each other than those driven electrode pairs with higher measured impedances. In some cases, electrodes associated with ablation electrodes 124 (e.g., one or more sensors 126) that are not driven can be measured to determine additional information about the location of the driving current pair.

[0264] Measurements received by the processing unit 109a and associated only with the drive current pairs, or in combination with measurements at the undriven sensor 126, may be fit into a model and / or compared to a lookup table to determine a displacement of the deformable portion 142 of the ablation electrode 124. For example, the determined displacement of the deformable portion 142 of the ablation electrode 124 may include a displacement in at least one of an axial direction or a transverse (radial) direction. It should be understood that due to the spatial separation of the current pairs in three-dimensional space, the determined displacement of the deformable portion 142 of the ablation electrode 124 may be in more than one direction (e.g., an axial direction, a transverse direction, and combinations thereof). Additionally, or alternatively, the determined displacement of the deformable portion 142 of the ablation electrode 124 may also correspond to a three-dimensional shape of the deformable portion 142 of the ablation electrode 124.

[0265] Based on the determined displacement of the deformable portion 142 of the ablation electrode 124, the processing unit 109a may send an indication of the shape of the deformable portion 142 of the ablation electrode 124 to the graphical user interface 110. Such an indication of the shape of the deformable portion 142 may include, for example, a graphical representation of the shape of the deformable portion 142 corresponding to the determined deformation.

[0266] In embodiments where the force-displacement relationship of the deformable portion 142 is reproducible (e.g., Fig. 9), the processing unit 109a may determine the force applied to the deformable portion 142 based on the determined displacement of the deformable portion 142. For example, using a lookup table, curve fitting, or other predetermined relationship, the processing unit 109a may determine the direction and magnitude of the force applied to the deformable portion 142 based on the magnitude and direction of the displacement of the deformable portion 142, as determined according to any one or more of the methods of determining displacement described herein. Therefore, it should be appreciated that the reproducible relationship between force and displacement along the deformable portion 142, combined with the ability to determine displacement using sensors 126 disposed along the deformable portion 142, may help determine whether an appropriate amount of force is applied during an ablation treatment, and may additionally, or alternatively, help determine an appropriate amount of energy and cooling for lesion formation.

[0267] Fig.15A -B schematically represents an exemplary method of cooling the ablation electrode 124 at the treatment site using irrigation liquid from the irrigation element 128. For clarity of illustration, a single jet of irrigation liquid is shown. However, it should be understood that multiple jets are emitted from the irrigation element 128 during use. In some embodiments, the irrigation liquid is generally uniformly directed to the inner portion 136 of the ablation electrode 124. Additionally, or alternatively, a portion of the irrigation liquid can be directed in a direction away from the irrigation element 128 and a portion of the irrigation liquid can be directed in a direction close to the irrigation element 128.

[0268] In the first step, if Fig.15A As shown, the ablation electrode 124 is positioned at the treatment site with its outer portion 138 disposed toward the tissue. Before ablation energy is delivered to the ablation electrode 124, a baseline flow of irrigation liquid is delivered to the irrigation element 128. The baseline flow of irrigation liquid can be, for example, about 0.5 psi higher than the patient's blood pressure to reduce the possibility of blood entering the irrigation element 128 and clotting. In addition, delivering the irrigation liquid at a lower pressure when ablation energy is not delivered to the ablation electrode 124 can reduce the amount of irrigation liquid delivered to the patient during treatment, compared to always delivering irrigation liquid at a higher pressure.

[0269] In the second step, if Fig. 15BAs shown, ablation energy is directed to at least a portion of an outer portion 138 of the ablation electrode 124 that is in contact with the tissue "T". As ablation energy is delivered to the ablation electrode 124, the pressure of the irrigation liquid can increase, resulting in a higher pressure flow directed from the irrigation element 128 toward the inner portion 136 of the ablation electrode 124. The higher flow of irrigation liquid at the inner portion 136 can result in turbulent flow, which can improve heat transfer away from the ablation electrode 124 compared to laminar flow. For example, when the deformable portion 142 is in an uncompressed state, each jet of irrigation liquid emitted from the irrigation element 128 can have a Reynolds number greater than about 2000 (e.g., greater than about 2300) at the inner portion 136 of the ablation electrode 124.

[0270] While certain embodiments have been described, other embodiments are possible in addition or alternatively.

[0271] For example, while it has been described that forming the deformable portion of the ablation electrode includes removing material from a flat sheet, other methods of forming the deformable portion of the ablation electrode may additionally or alternatively be included. For example, the deformable portion of the ablation electrode may be formed by removing material (e.g., by laser cutting) from a tube of material (e.g., a nitinol tube). With the material removed, the tube may be bent into a generally closed shape, such as the generally spherical shape described herein.

[0272] As another example, while forming a deformable portion of an ablation electrode by removing material from a single structure of material (e.g., from a plate and / or tube) has been described, other methods of forming a deformable portion of an ablation electrode may additionally or alternatively be possible. For example, the deformable portion of the ablation electrode may include a mesh and / or braid. The mesh material may be, for example, nitinol. It should be understood that the mesh and / or braided portion of the ablation electrode may move between compressed and uncompressed states.

[0273] As another example, although it has been described that the ablation electrode has a deformable portion and a sensor is set along the deformable portion to determine the displacement of the deformable portion, other configurations for determining the displacement may also be used in addition or alternatively. For example, a plurality of coils may be set along the deformable portion of the ablation electrode. In use, some of the plurality of coils may be used to transmit a magnetic field, while other coils of the plurality of coils may be used to measure the generated magnetic field. The measured signal may be used to determine the displacement of the deformable portion. The determined displacement of the deformable portion may be used, for example, to determine the shape of the deformable portion, and may be used in addition or alternatively to determine the force applied to the deformable portion according to any one or more of the methods described herein. In addition, or alternatively, a plurality of ultrasonic transducers or other types of image sensors may be set along the deformable portion of the ablation electrode, on an irrigation element coated by the deformable portion, or a combination thereof. The signal measured by the ultrasonic transducer or other type of image sensor may be used to determine the displacement of the deformable portion.

[0274] As yet another example, although the deformable portion of the ablation electrode has been described as being self-expandable from a compressed state to an uncompressed state, the deformable portion of the ablation electrode may additionally or alternatively be expanded and / or contracted by applying an external force. For example, any one or more catheters such as those described herein may include a sliding member extending from a handle through a catheter shaft to the ablation electrode. The sliding member may be coupled (e.g., mechanically coupled) to the ablation electrode so that axial movement of the sliding member relative to the catheter shaft can apply compression and / or expansion forces on the deformable portion of the ablation electrode. For example, distal movement of the sliding member may push the ablation electrode in a distal direction relative to the catheter shaft so that the deformable portion of the ablation electrode is folded to a compressed state (e.g., for retraction, transmission, or both). In addition, or as an alternative, proximal movement of the sliding member may pull the ablation electrode in a proximal direction relative to the catheter shaft so that the deformable portion of the ablation electrode is expanded to an uncompressed state (e.g., for therapeutic transmission). In some embodiments, the sliding member may be mechanically coupled to a portion of the handle so that movement of the sliding member can be controlled at the handle. It should be appreciated that the sliding member can be an elongated member (e.g., a wire) that is flexible enough to bend with movement of the shaft while being rigid enough to resist buckling or other types of deformation in response to the forces required to move the deformable portion of the ablation electrode.

[0275] As yet another example, although the flushing element has been described as comprising a substantially rigid rod and ball configuration, other configurations of the flushing element are also possible, additionally or alternatively. Fig.16, the flushing element 128a may include an axial portion 166 and a helical portion 168. The flushing element 128a may be used in any one or more of the catheters described herein. For example, in addition to or in lieu of the flushing element 128a described herein, Figure 3-5 The flushing element 128 described above may also be used as flushing element 128a.

[0276] The axial portion 166 and the helical portion 168 are in fluid communication with each other and, in certain embodiments, have an irrigation lumen defined by the catheter shaft. At least the helical portion 168 and, optionally, the axial portion 166 define a plurality of irrigation ports 134a along at least a portion of the length of the irrigation element 128a. In use, the delivery of irrigation liquid through the irrigation ports 134a may create an axially, circumferentially, and / or radially distributed pattern. Unless otherwise specified or clear from the context, in addition to or in lieu of the irrigation element 128( Figure 3 ), an irrigation element 128a may also be used. Thus, for example, it should be understood that the irrigation element 128a may be disposed along the inner portion 136 ( Figure 3 ) provides substantially uniform cooling.

[0277] The flushing port 134a may be similar to the flushing element 128 ( Figure 3 ) defined by the flushing port 134. For example, the flushing port 134a can have the same size and shape as the flushing port 134 defined by the flushing element 128. Additionally, or alternatively, the flushing port 134a can have the same opening area as the flushing port 134 defined by the flushing element 128.

[0278] The axial portion 166 of the irrigation element 128 can be coupled to the catheter shaft (e.g., coupled to the distal portion of the catheter shaft, such as with respect to Figure 2-4 The distal end portion 132 of the catheter shaft 122 described above. Additionally, or alternatively, the axial portion 166 can extend distally from the catheter shaft. For example, the axial portion 166 can extend distally from the catheter shaft along an axis defined by the flushing lumen.

[0279] Typically, the helical portion 168 extends away from the axial portion 166 in a radial direction. In certain embodiments, the maximum radial dimension of the helical portion 168 is less than the outer diameter of the catheter shaft. In such embodiments, the helical portion 168 can remain in the same orientation during delivery and use of the catheter (e.g., during any of the delivery and / or use methods described herein). However, in some embodiments, the helical portion 168 can be elastically compliant (e.g., a nitinol tube shape configured in a helical configuration) such that the maximum radial extent of the helical portion 168 is less than the outer diameter of the catheter shaft during delivery to the treatment site, and is expanded such that the maximum radial extent of the helical portion 168 is greater than the outer diameter of the catheter shaft in the deployed position. It should be understood that in the deployed position, the helical portion can be positioned closer to the inner surface of the ablation electrode, which can facilitate delivery of irrigation fluid to the inner surface of the ablation electrode.

[0280] In addition to extending away from the catheter shaft in a radial direction, the helical portion 168 also extends in a circumferential direction relative to the axial portion 166. For example, the helical portion 168 can extend circumferentially around the axial portion 166 through at least one rotation. Such circumferential extension of the helical portion through at least one rotation can promote substantially uniform dispersion of irrigation liquid around the inner surface of the generally spherical ablation electrode coated with the helical portion 168.

[0281] Optionally, the helical portion 168 may also extend in an axial direction relative to the axial portion 166. Thus, as used herein, in the most general sense, the helical portion 168 should be understood to include any of a variety of different helical patterns that are generally planar and / or extend axially relative to the axial portion 166.

[0282] As another example, although the flushing element has been described as having a discrete number of uniform flushing ports, other embodiments are also possible, additionally or alternatively. Fig.17 , the irrigation element 128b can be a porous membrane defining a plurality of openings 170. Typically, the plurality of openings 170 are a property of the material forming the irrigation element 128c, and are therefore distributed (e.g., non-uniformly distributed and / or uniformly distributed) across the surface of the irrigation element 128b. Since the openings 170 are a property of the material forming the irrigation element 128b, the plurality of openings 170 can be substantially smaller than irrigation ports formed in the irrigation element by laser drilling or other similar secondary processing. Unless otherwise indicated or clear from the context, in addition to or in lieu of the irrigation element 128( Figure 3 ) and / or flushing element 128a ( Fig.16), an irrigation element 128b may also be used. Thus, for example, it should be appreciated that the irrigation element 128b may provide substantially uniform cooling along the inner portion 136 of the ablation electrode 124 ( Figure 3 ).

[0283] In certain embodiments, the flushing element 128b may include an arrangement of one or more polymers. This arrangement may be porous and / or microporous, and as an example, may be formed by polytetrafluoroethylene (PTFE). In such an embodiment, the openings 170 may be defined by the spaces between the polymer fibers or by the polymer fibers themselves, and are generally distributed along the entire surface of the flushing element 128b. It should be understood that a large number of openings 170 along the entire surface of the flushing element 128b and the distribution of the openings 170 can produce a substantially uniform flushing liquid spray. In addition, a large number of openings 170 along the entire surface of the flushing element 128b and the distribution of the openings 170 can promote the interaction of multiple different fluid jets, and therefore promote the development of turbulence of the flushing liquid.

[0284] The size and distribution of the openings 170 defined between or by the polymer fibers can allow the flushing element 128b to function as a selective filter. For example, since blood molecules are generally larger than water molecules, the size (e.g., average size) of the openings 170 can be smaller than blood molecules but larger than water molecules. It should be understood that such a size of the openings 170 can allow flushing liquid to flow out of the flushing element 128b while preventing blood molecules from entering the flushing element 128b and thereby clotting.

[0285] The arrangement of one or more polymers of the irrigation element 128b may include electrospun polytetrafluoroethylene and / or expanded polytetrafluoroethylene (ePTFE). In certain embodiments, the arrangement of one or more polymers is non-woven (e.g., Fig.17 ), resulting in substantially non-uniform spacing between the fibers, such that the openings 170 defined by the spacing between the fibers are non-uniformly sized and / or non-uniformly distributed. In some embodiments, the irrigation element 128b may include a woven or fabric arrangement of polymers through which irrigation liquid is directed. For example, the fabric may be made of one or more polymers or other biocompatible materials woven together to form a substantially uniform porous barrier through which irrigation liquid can pass during use. Examples of polymers that can be arranged together into a fabric suitable for forming the irrigation element 128c include, but are not limited to, one or more of the following: polyester, polypropylene, nylon, PTFE, and ePTFE.

[0286] In some embodiments, the irrigation element 128b can include an open-cell foam material such that the openings 170 are defined by cells of the open-cell foam material along the surface of the irrigation element 128b. In such embodiments, the irrigation liquid can move through a tortuous path defined by the open-cell foam material until the irrigation liquid reaches the openings 170 along the surface of the irrigation element 128b, where the irrigation liquid exits the irrigation element 128b. It should be understood that in such embodiments, the openings 170 are distributed along the entire surface of the irrigation element 128b, resulting in a generally uniform and generally turbulent pattern of irrigation liquid spray emitted from the irrigation element 128b.

[0287] As yet another example, although the flushing element has been described as comprising a resilient, expandable helical portion, other types of resiliently expandable flushing elements are also possible, additionally or alternatively. Fig.18 , the irrigation element 128c can be a flexible, inflatable structure, such as a balloon, disposed along the distal portion 132' of the catheter shaft 122' and in fluid communication with the lumen 151'. In some embodiments, the irrigation element 128c and the ablation electrode 124' can each be coupled to the distal portion 132' of the catheter shaft 122'. Unless otherwise specified or clear from the context, in Fig.18 Elements designated by prime (') element numbers in the drawings are similar to corresponding elements designated by non-prime element numbers in other figures of the present disclosure and, therefore, should be understood to include the features of the corresponding elements designated by non-prime numbers. Thus, as an example, unless otherwise specified, ablation electrode 124' should be understood to correspond to ablation electrode 124( Figure 3 ).

[0288] In certain embodiments, the flushing element 128c is expandable. For example, the flushing element 128c can be uninflated and / or underinflated in a state where the distal portion 132' of the catheter shaft 122' is delivered to a treatment site according to any of the methods described herein. In this delivery state, the flushing element 128c can be delivered to the treatment site with a low profile (e.g., a profile that is less than or equal to the maximum outer portion dimension of the catheter shaft 122'). At the treatment site, the flushing element 128c can be inflated to expand from the delivery state to the expanded state. For example, the flushing element 128c can expand in a radial direction beyond the outermost dimension of the catheter shaft 122'.

[0289] The irrigation element 128c can be a non-compliant balloon or a semi-compliant balloon. In such an embodiment, the irrigation element 128c can generally resist deformation when in an inflated state. Therefore, when the irrigation element 128c is non-compliant or semi-compliant, the irrigation element 128c can resist deformation when in contact with the inner portion 136' of the deformable portion 142' of the ablation electrode 124'. Compared to a compliant balloon, this resistance to deformation of the irrigation element 128c can help, for example, control the flow of irrigation liquid through the irrigation element 128c.

[0290] In some embodiments, the flushing element 128c is a balloon formed of one or more polymers. The polymer can be, for example, sufficiently flexible to expand from a delivery state to an expanded state while withstanding the forces generated by the movement of flushing liquid through the flushing element 128c. Where the flushing element 128c is formed of one or more polymers, flushing ports can be formed in the polymer by laser drilling or other similar secondary processing. Examples of polymers that can be used to form the flushing element 128c include one or more of the following: thermoplastic polyurethane, silicone, poly(ethylene terephthalate), and polyether block amides.

[0291] The flushing element 128c can define a plurality of flushing ports 134c. The flushing ports 134c can be similar to those formed by the flushing element 128( Figure 3 ) defined by the flushing port 134. For example, the flushing port 134c may have the same size and shape as the flushing port 134 defined by the flushing element 128. Additionally, or alternatively, the flushing port 134c may have the same opening area as the flushing port 134 defined by the flushing element 128.

[0292] In use, irrigation liquid can flow from the lumen 151' into the irrigation element 128c and can exit the irrigation element 128c through the plurality of irrigation ports 134c. Typically, the plurality of irrigation ports 134c can have a combined area that is less than the cross-sectional area of ​​the lumen 151', such that as the irrigation liquid moves through the irrigation element 128c, fluid pressure can build up in the expandable element 128c. It should be appreciated that the pressure in the expandable element 128c can then expand the irrigation element 128c (e.g., from a delivery state to an expanded state) due to the flow of irrigation liquid through the irrigation element 128c.

[0293] In some embodiments, the volume defined by the inner portion 136' of the ablation electrode 124' in an expanded or uncompressed state is greater than the volume defined by the irrigation element 128c in an expanded state. Thus, for example, when the irrigation element 128c is in the expanded state, the inner portion 136' of the ablation electrode 124' (e.g., along the deformable portion 142') can be spatially separated from at least a portion of the surface area of ​​the irrigation element 128c. This spatial separation can be advantageous, for example, to facilitate turbulence of irrigation liquid emitted from the irrigation port 134c before reaching the inner portion 136' of the ablation electrode 124'. It should be appreciated that such turbulence of the flow of irrigation liquid at the inner portion 136' of the ablation electrode 124' can contribute to effective cooling of the ablation electrode 124' compared to less turbulent and / or laminar flow.

[0294] The irrigation element 128c can be wrapped around the ablation electrode 124' in an uncompressed state, for example, to substantially cool the entire interior portion 136' of the ablation electrode 124'. Additionally, or alternatively, wrapping the irrigation element 128c with the ablation electrode 124' can reduce the likelihood that the irrigation element 128c is exposed to undesirable forces (e.g., forces that may be encountered when the ablation electrode 124' and the irrigation element 128c are moved to a treatment site).

[0295] In the expanded state, the irrigation element 128c can include a generally ellipsoidal portion. As used herein, a generally ellipsoidal portion can include a generally spherical shape and variations of a generally spherical shape.

[0296] In certain embodiments, irrigation ports 134c are defined on the ellipsoidal portion of irrigation element 128c. Thus, in such embodiments, the ellipsoidal portion of irrigation element 128c can facilitate directing irrigation liquid in a plurality of different axial and radial directions. For example, irrigation ports 134c can be spaced circumferentially (e.g., around the entire circumference) around the ellipsoidal portion of irrigation element 128c such that irrigation liquid can be directed toward inner portion 136' of ablation electrode 142' along a plurality of different radial directions. As an additional or alternative example, irrigation ports 134c can be spaced axially (e.g., along the entire axial dimension of the ellipsoidal portion of irrigation element 128c) such that irrigation liquid can be directed toward inner portion 136' of ablation electrode 142' along a proximal and / or distal direction.

[0297] A plurality of sensors 126' may be supported on the deformable portion 142' of the ablation electrode 124'. In use, the plurality of sensors 126' may be used to detect deformation of the deformable portion 142'. For example, the irrigation element 128c may include the sensor 172, and an electrical signal may be driven between one or more electrodes on the irrigation element 128c and each of the plurality of sensors 126' according to any of the methods described herein.

[0298] Although multiple sensors 126' can be used in conjunction with the sensor 172 on the flushing element 128c, other configurations for detecting deformation of the deformable portion 142' are also possible or alternative. Fig.19 and 20 , a plurality of sensors 174 may be supported along ablation electrode 124" and at least partially enclosed by irrigation element 128c". Unless otherwise indicated or clear from the context, in Fig.19 and 20 Elements designated by double prime (") element numbers in the drawings are similar to corresponding elements designated by non-prime numbers and / or single prime numbers in other figures disclosed in the present application, and therefore, should be considered to include the features of corresponding elements designated by non-prime numbers and / or single prime numbers. As an example, unless otherwise specified or clear from the context, flushing element 128c" should be understood to include flushing element 128c( Fig.18 As another example, unless otherwise specified or clear from the context, ablation electrode 124" should be understood to include ablation electrode 124 ( Figure 3 and 4 ) and / or ablation electrode 124'( Fig.18 ) characteristics.

[0299] Each sensor 174 may include a flexible printed circuit and / or a thermistor similar to any of the flexible printed circuits and / or thermistors described herein, including those described above with respect to Fig.10 and Fig.11 A flexible printed circuit 150 and / or a thermistor 152 are depicted.

[0300] In the uncompressed state of the ablation electrode 124", the inner portion 136" of the ablation electrode 124" is spatially separated from at least a portion of the surface of the irrigation element 128c", so that, for example, at least one of the multiple sensors 174 is not in contact with the irrigation element 128c". In some embodiments, the ablation electrode 124" in the uncompressed state is not in contact with any of the multiple sensors 174. That is, in this embodiment where the ablation electrode 124" in the uncompressed state is spatially separated from one or more of the sensors 126", the default arrangement of the sensor 126" is away from the irrigation element 128c.

[0301] The ablation electrode 124" may include a deformable portion 142" that can elastically compliant from a compressed state (e.g., wherein the inner portion 136" of the ablation electrode 124" is in contact with the irrigation element 128c") to an uncompressed state (e.g., wherein the inner portion 136" of the ablation electrode 124" is spatially separated from at least a portion of the surface of the irrigation element 128c". Thus, in this embodiment, deformation of the deformable portion 142" can cause one or more of the multiple sensors 174 to contact the irrigation element 128c", and detecting the contact can be used to determine the shape of the deformable portion 142" in response to a deformation force (e.g., a force applied by contact with tissue).

[0302] The sensors 174 can be axially and / or circumferentially spaced from each other along the deformable portion 142″ of the ablation electrode 124″. For example, a first group of sensors 174 can be disposed distally to a second group of sensors 174 along the ablation electrode 124″ (e.g., along the deformable portion 142″). It should be understood that the spatial resolution of the detected deformation of the deformable portion 142″ can be a function of the number and spatial distribution of the sensors 174, with a larger number of evenly spaced sensors 174 generally providing increased spatial resolution compared to a smaller number of clustered sensors 174.

[0303] In use, an electrical signal may be driven between at least one sensor 174 and another sensor 174. The measured electrical signal generated between at least one sensor 174 and another sensor 174 may be processed by any processing unit described herein (e.g., Figure 1 The described processing unit 109a) receives it.

[0304] Deformation of the deformable portion 142" of the ablation electrode 124" can be detected based at least in part on a measured electrical signal generated between at least one sensor 174 and another sensor 174. For example, when the deformable portion 142" of the ablation electrode 124" is deformed, one or more of the sensors 174 can contact the irrigation element 128c". It should be understood that a certain amount of force is required to deform the deformable portion 142" by being sufficient to cause one or more sensors 174 to contact the irrigation element 128c". As used herein, the force is considered to be a threshold at least in the following sense, that is, a force below the threshold is insufficient to cause one or more sensors 174 to contact the irrigation element 128c", and therefore no contact between one or more sensors 174 and the irrigation element 128 is detected.

[0305] Contact between the one or more sensors 174 and the flushing element 128c", for example, can be detected as a change in a measured electrical signal received by the processing unit from the corresponding one or more sensors 174. As a non-limiting example, contact between the one or more sensors 174 and the flushing element 128c can be detected as an increase in the impedance of the corresponding one or more electrical signals associated with the one or more sensors 174 in contact with the flushing element 128c.

[0306] Detecting deformation of the deformable portion 142" of the ablation electrode 124" may, for example, include determining whether one or more of the sensors 174 are in contact with the irrigation element 128c. Additionally, or alternatively, detecting deformation of the deformable portion 142" based on the measured electrical signal may include detecting the degree and / or direction of deformation of the deformable portion 142". That is, the degree and / or direction of deformation of the deformable portion 142" may be determined based on the number and / or position of one or more sensors 174 detected as being in contact with the irrigation element 128c.

[0307] An indication of the determined state of the deformable portion 142" may be sent to a graphical user interface, such as any one or more of the graphical user interfaces described herein (e.g., regarding Figure 1 110 described). In some embodiments, the degree and / or orientation of the deformation of the deformable portion 142" can be sent to the graphical user interface. For example, based on which sensors 174 are detected as being in contact with the flushing element 128c, a corresponding representation of the compression state of the deformable portion 142" can be sent to the graphical user interface. The corresponding representation of the compression state of the deformable portion 142" can be based on, for example, a lookup table of shapes corresponding to different combinations of sensors 174 detected as being in contact with the flushing element 128c.

[0308] An exemplary method of manufacturing a catheter including an irrigation element 128c' may include coupling (e.g., using an adhesive) the irrigation element 128c' to a distal portion 132' of a catheter shaft 122'. A deformable portion 142' may be formed according to any one or more of the methods described herein, and the deformable portion 142' may be positioned relative to the irrigation element 128c' such that an inner portion 136' of the ablation electrode 124' surrounds the irrigation element 128c'. The deformable portion 142' may be coupled to the catheter shaft 122' relative to the irrigation element 128c' such that, in a compressed state, the inner portion 136' of the ablation electrode 124' is in contact with the irrigation element 128c', and in an uncompressed state, the inner portion 136' of the ablation electrode 124' along the deformable portion 142' is spatially separated from the irrigation element 128c'.

[0309] As another example, while certain configurations of struts along the deformable portion of the ablation electrode to form a hole have been described, other configurations are also possible, additionally or alternatively. Fig.21 and 22 , the catheter 204 may include an ablation electrode 224 having struts 244b defining a plurality of holes 247, the struts 244b being gradually ganged together in a direction from a proximal region to a distal region of a deformable portion 242 of the ablation electrode 224. For the sake of efficient and clear description, unless otherwise explicitly stated or clearly stated from the context, Fig.21 and 22 Components designated by 200-series component numbers are similar to or interchangeable with components designated by 100-series component numbers (including prime and double prime component numbers) described herein, and therefore, except for noting differences or describing references Fig.21 and 22 Features that are more easily understood are not described separately from the corresponding components with 100-series component numbers. Thus, for example, unless otherwise expressly stated or clear from the context, Fig.21 and 22 The conduit 204 in FIG. 1 should generally be understood to be similar to the conduit 104 ( Figure 1-4 ).

[0310] As used herein, a configuration in which struts 244b are gradually coupled together may include an arrangement of struts 244b wherein the number of holes in the plurality of holes 247 decreases in a given direction. Thus, for example, the struts 244b may be gradually coupled together in a direction toward the distal end of the deformable portion 242 such that the number of holes 247 defined by the struts decreases in a direction toward the distal end of the deformable portion 242. Thus, a closed end of the deformable portion 242 of the ablation electrode 224 may be formed by joining together relatively fewer struts 244b, as compared to a configuration in which the struts are uniformly arranged around a shape. This may be advantageous, for example, to achieve acceptable manufacturing tolerances or further, or alternatively, to promote a substantially uniform distribution of current density along the deformable portion 242.

[0311] In some embodiments, the holes in the plurality of holes 247 can be defined by different numbers of struts 244b, which can help achieve a target distribution of current density along the deformable portion 242. For example, a first set of holes in the plurality of holes 247 can be defined by a plurality of struts 244b. Fig. 12B The plurality of holes 247 may be defined by at least four struts 244b of the eyelet 157, and a second group of holes in the plurality of holes 247 may be defined by fewer struts than the first group of holes. For example, a first group of holes in the plurality of holes 247 may be defined by at least four struts 244b.

[0312] In some embodiments, at least some of the plurality of holes 247 are symmetrical. Such symmetry can, for example, help achieve a substantially uniform current density in the deformable portion 242 of the ablation electrode 224. Additionally, or alternatively, such symmetry can also be used to achieve appropriate compressibility of the deformable portion for delivery to a treatment site (e.g., via a sheath), while also achieving appropriate expansion of the deformable portion for use at the treatment site.

[0313] At least some of the holes 247 have mirror symmetry. As used herein, a mirror symmetrical shape includes a shape that is generally symmetrical about a plane that intersects the shape, whose general symmetry allows for the presence or absence of a sensor 226 on one or both sides of the plane that intersects the shape. For example, at least some of the holes 247 may have mirror symmetry about a mirror symmetry plane that passes through the corresponding hole 247 and contains the central axis CL'-CL' defined by the catheter shaft 222 and extends from the proximal portion of the catheter shaft 222 to the distal portion. Fig. 22In the side view shown, the mirror symmetry planes of some of the plurality of holes 247 are perpendicular to the page and pass through the central axis CL'-CL'. Additionally, or alternatively, it should be understood that the entire deformable portion 242 of the ablation electrode 224 can be symmetrical about a plane including the central axis CL'-CL', such as a plane perpendicular to the page and passing through the central axis CL'-CL'.

[0314] Mirror symmetry of at least some of the plurality of holes 247 and / or the entire deformable portion 242 can be useful, for example, for uniform distribution of current density. Additionally, or alternatively, the symmetry can facilitate expansion and contraction of the deformable portion 242 of the ablation electrode 224 in a predictable and repeatable manner (e.g., with little plastic deformation). For example, each of the plurality of holes 247 can be symmetrical about its corresponding symmetry plane in the compressed state and the uncompressed state of the deformable portion 242 of the ablation electrode 224. Through such symmetry in the compressed state and the uncompressed state of the deformable portion 242, the deformable portion 242 can be expanded during expansion with little circumferential translation of the deformable portion 242, which can help to accurately understand the position of the deformable portion 242 during delivery and deployment of the deformable portion 242.

[0315] The catheter 204 can be formed according to any one or more of the various methods described herein. For example, the ablation electrode 224 can be formed from a flat plate or tube, as described herein, such that the ablation electrode 224 has two open ends. According to any of the various methods described herein, the fastener 241b can be inserted through one end of at least some of the struts 244b to couple the ends of the struts 244b to close one of the two open ends of the ablation electrode 224. The open end of the ablation electrode 224 (e.g., the end opposite the fastener 241b) can be coupled to the distal portion 232 of the catheter shaft 222 to form the catheter 204.

[0316] The following simulations and experiments describe the uniformity of current density associated with the ablation electrode 224 in an uncompressed state. It should be understood that the simulations and experiments described below are set forth only as examples, and nothing in the simulations or experiments should be construed as limiting the entire scope of the present disclosure.

[0317] Reference now Figure 21-23, the irrigation element 228 can be coated by the deformable portion 242 of the ablation electrode 224, so that the deformable portion 242 forms an enclosure around the irrigation element 228. The irrigation element 228 can be any of a variety of different irrigation elements described herein, and can be in fluid communication with the catheter shaft 222. For example, the irrigation element 228 can be disposed generally along the central axis CL'-CL', can extend distally from the distal portion 232 of the catheter shaft 222, and can also or alternatively define a plurality of irrigation ports 234 disposed along the irrigation element 228 to direct irrigation liquid toward the deformable portion 242 of the ablation electrode 224. Additionally, or alternatively, a central electrode 235 can be disposed along the irrigation element 228 and directly or indirectly coupled to the distal portion 232 of the catheter shaft 222.

[0318] The irrigation element 228 may include a nozzle portion 229 disposed along an end of a generally cylindrical body 230. A plurality of irrigation ports 234 may be defined along one or both of the nozzle portion 229 and the generally cylindrical body 230. In general, the plurality of irrigation ports 234 may be sized and positioned to direct fluid from the nozzle portion 229 in a plurality of different spray patterns. For example, the nozzle portion 229 may be generally hemispherical to facilitate orienting at least some of the plurality of irrigation ports 234 in a plurality of different directions. Additionally, or alternatively, at least some of the plurality of irrigation ports 234 may be spaced axially or circumferentially or axially and circumferentially around the cylindrical body 230. In some cases, the orientation of the plurality of irrigation ports 234 along the nozzle portion 229, the cylindrical body 230, or a combination thereof may be used to produce a generally uniform distribution of irrigation liquid from the irrigation element 228 toward the ablation electrode 224. Additionally, or alternatively, the orientation of the plurality of irrigation ports 234 in a plurality of different directions may be used to create turbulence in the irrigation liquid, which may be used to promote heat transfer away from the ablation electrode 224. Still further, or alternatively, the orientation of the plurality of irrigation ports 234 in a plurality of different directions may also be used to entrain blood and increase the volume velocity of the fluid over the ablation electrode 224 and tissue.

[0319] In the absence of a force applied to the deformable portion 242 of the ablation electrode 224, the center electrode 235 is spaced apart from the sensor 226. When the deformable portion 242 is brought into contact with tissue by a force applied to the deformable portion 242, it should be understood that, independent of the orientation of the deformable portion 242 relative to the tissue, the deformable portion 242, and therefore the sensor 226, is in initial contact with the tissue before the center electrode 235 is initially in contact with the tissue. In some embodiments, the center electrode 235 remains spaced apart from the tissue under normal operation. That is, the deformable portion 242 of the ablation electrode 224 can have sufficient rigidity to keep the center electrode 235 spaced apart from the tissue within a normal range of contact forces of less than about 100 g (e.g., less than about 50 g).

[0320] In some embodiments, the irrigation element 228 can be one or both of electrically isolated and thermally isolated from the center electrode 235. In this case, the irrigation element 228 can be a ground electrode of the measurement circuit to reduce noise, reduce measurement errors, or both. For example, in the case where the irrigation element 228 is a ground electrode, the irrigation element 228 can be connected to the ground node of the measurement circuit through a resistor (e.g., a 50kΩ resistor). As a further or alternative example, the irrigation element 228 can be a drive electrode that is part of the analog feedback circuit, and electrical energy can be driven by the irrigation element 228 so that the voltage measured on the reference electrode (e.g., the center electrode 235) is reduced. In general, it should be understood that the use of the irrigation element 228 as a ground electrode or as a drive electrode, as the case may be, can reduce or eliminate the need to carry a ground or drive electrode on a separate device (e.g., a right leg electrode). This reduction in the complexity associated with grounding the measurement circuit is useful, for example, for reducing the complexity of the medical procedure.

[0321] In certain embodiments, the thermocouple 251 can be disposed along the irrigation element 128. For example, the thermocouple 251 can be disposed on one or both of the outer surface or the inner surface of the irrigation element 128. The thermocouple 251 can be in electrical communication with, for example, the processing unit 109a. In use, the processing unit 109a can adjust one or more parameters related to the delivery rate of irrigation liquid through the irrigation element 128, the delivery time of irrigation liquid through the irrigation element 128, or a combination thereof based on the signal received from the thermocouple 251. Additionally, or alternatively, the processing unit 109a can alert the physician if the signal received from the thermocouple 251 is inconsistent with the expected irrigation rate.

[0322] The electrical activity detected (e.g., passively detected) by the central electrode 235 and the sensor 226 (which functions as a surface electrode) can form the basis of a corresponding electrogram associated with each unique pairing of the central electrode 235 and the sensor 226. For example, in an embodiment with six sensors 226, the central electrode 235 can form six electrode pairs with the sensors 226, which in turn form the basis of six corresponding electrograms.

[0323] The electrogram formed from the electrical signals received from each respective electrode pair (i.e., the central electrode 235 and the respective one of the sensors 226) can be generated by any of a number of different methods. In general, the electrogram associated with a respective electrode pair can be based on the difference between the signals from the electrodes in the pair, and thus, more specifically, can be based on the difference between the electrical signals received from the central electrode 235 and the electrical signals received from the respective one of the sensors 226. For example, such an electrogram can be filtered or otherwise further processed to reduce noise and / or emphasize cardiac electrical activity.

[0324] Because the center electrode 235 remains spaced apart from the sensor 226 and the tissue at an intermediate distance within the range of forces experienced by contact between the tissue and the deformable portion 242 of the ablation electrode 224, the electrogram formed from each electrode pair can advantageously be a near-monopolar electrogram. As used herein, a near-monopolar electrogram includes an electrogram formed based on the difference between two electrodes that are greater than about 2 mm and less than about 6 mm apart and oriented so that one electrode remains spaced apart from the tissue. In some embodiments, in the absence of force applied to the deformable portion 242 of the ablation electrode 224, the center electrode 235 is spaced apart from the sensor 226 by a distance greater than about 2 mm and less than about 6 mm.

[0325] A near-unipolar electrogram associated with a central electrode 235 spaced apart from the sensor 226 can provide certain advantages over a monopolar configuration (i.e., a configuration having an electrode spacing greater than 6 mm) and an over bipolar configuration (i.e., a configuration having an electrode spacing equal to or less than 2.5 mm and / or allowing the two electrodes to be spaced apart close to the tissue). For example, compared to a monopolar electrogram, a near-unipolar electrogram formed based on signals received from the central electrode 235 and the sensor 226 is less noisy and, additionally or alternatively, less susceptible to remote interference from electrical activity away from the tissue of interest. Moreover, compared to a monopolar electrogram, a near-unipolar electrogram does not require a reference electrode on a separate catheter or other device. As a further or alternative example, compared to a bipolar electrogram, a near-unipolar electrogram formed based on signals received from the central electrode 235 and the sensor 226 is generated from an electrode pair, only one of which is in contact with the tissue, such that the resulting electrogram waveform is from one tissue site, making it less complicated to interpret. Additionally or alternatively, the signal from a near-monopolar electrogram formed based on signals received from a central electrode 235 in contact with tissue and sensor 226 may have a more consistent morphology and / or a larger amplitude than a bipolar electrogram produced from a pair of electrodes in contact with tissue, at least because the central electrode 235 is always oriented away from the tissue compared to the sensor 226 in the electrode pair in contact with the tissue.

[0326] The sensors 226 may be any of a variety of different sensors described herein, and may additionally or alternatively be arranged on the deformable portion 242 of the ablation electrode 224 according to any of a variety of different arrangements described herein. For example, the sensors 226 may be non-coplanar with respect to one another in the absence of an external force applied to the deformable portion 242 of the ablation electrode 224 encasing the central electrode 235. It should be appreciated that the electrograms generated from the sensors 226 arranged in such a non-coplanar configuration may be used to provide better directional information about electrical activity in tissue than in a planar arrangement.

[0327] The sensors 226 can be electrically isolated from the deformable portion 242 of the ablation electrode 224, with the sensors 226 acting as surface electrodes that passively detect electrical activity in tissue proximate to each respective sensor 226 without interference from the deformable portion 242 of the ablation electrode 224. At least some of the sensors 226 can be disposed at least partially along an outer portion of the deformable portion 242 of the ablation electrode 224, the deformable portion 242 of the ablation electrode 224 being located between the central electrode 235 and at least a portion of each respective one of the sensors 226 along the outer portion. Additionally, or alternatively, at least some of the sensors 226 can be disposed at least partially along an inner portion of the deformable portion 242 of the ablation electrode 224. In such an embodiment, each sensor 226 can be proximate to the tissue without contacting the tissue when the deformable portion 242 of the ablation electrode 224 contacts the tissue. Thus, for example, at least some of the sensors 226 can extend through the ablation electrode 224.

[0328] Reference now Figure 1 and 22 -23, catheter 204 can replace Figure 1 104 in the catheter. Thus, the electrical signals from the sensor 226 and the center electrode 235 can be directed to the catheter interface unit 108, and therefore, unless otherwise specified or clear from the context, it should be understood to form a basis for detecting contact with tissue, detecting deformation of the ablation electrode 224, or a combination thereof according to any one or more of the methods described herein. For example, the signal can be sent to an electrical input stage associated with the catheter interface unit 108. In some embodiments, the difference between the electrical signals is determined by an electronic circuit (e.g., a voltage amplifier with a differential input). Additionally, or alternatively, the difference between the electrical signals can be determined by the processing unit 109a of the catheter interface unit 108.

[0329] Typically, the storage medium 109b of the catheter interface unit 108 may have computer executable instructions stored thereon for causing the processing unit 109a to acquire a plurality of electrograms (e.g., an electrogram for each electrode pair formed by the central electrode 235 and each corresponding sensor 226). The storage medium 109b may also or alternatively store thereon instructions for causing the processing unit 109a to display a representation of at least one of the plurality of electrograms on the graphical user interface 110. In some embodiments, the storage medium 109b may store thereon instructions for causing the processing unit 109a to determine a voltage map associated with the plurality of electrograms, the voltage map corresponding to, for example, the electrical activity of the patient's heart. In some embodiments, the storage medium 109b may store thereon instructions for causing the processing unit 109a to display the voltage map on the graphical user interface 110. The displayed electrogram, alone or in combination with the displayed voltage map, may be used to selectively treat tissue of the heart (eg, to deliver ablation energy from the deformable portion 242 of the ablation electrode 224 to tissue in a heart chamber).

[0330] Reference now Fig.24 , flushing element 228 ( Fig.23 ) can be formed from a generally planar sheet of material that is rolled into a tube 233 (e.g., a generally cylindrical tube). It should be appreciated that various features of the irrigation element 228 can be formed in the generally planar sheet before or while the generally planar sheet is formed into the tube 233. More specifically, material can be removed from the generally planar sheet of material (e.g., by laser cutting) to form leaflets 236, a plurality of irrigation ports 234, or a combination thereof. Compared to forming features on a curved material, it should be appreciated that forming leaflets 236, a plurality of irrigation ports 234, or a combination thereof on a generally planar sheet can reduce manufacturing complexity and, additionally or alternatively, facilitate control of spacing and size tolerances associated with the plurality of irrigation ports 234, which in turn facilitates control of a spray pattern of irrigation liquid through the plurality of irrigation ports 234.

[0331] Once the tube 233 is formed, the flushing element 228 ( Fig.23 ) can be formed by, for example, bending the leaflets 236 toward each other to form a generally closed end of the irrigation element 228. In some embodiments, the bent leaflets 236 can be connected to each other (e.g., by welding) at the seams between adjacent leaflets 236.

[0332] Reference now Fig.21, 22 and 25, one or more of the sensors 226 can be supported on the deformable portion 242 of the ablation electrode 224 by an orifice 237 defined at the intersection of the struts 244b (e.g., at the connection point). For example, the sensor 226 can extend from the outer surface of the deformable portion 242 to the inner surface of the deformable portion 242. Arranged in this manner, the sensor 226 can contact the tissue along the outer surface of the deformable portion 242, and additionally or alternatively, the portion of the sensor 226 extending to the inner surface of the deformable portion 242 can be connected to a wire that carries an electrical signal as needed to use the sensor 226 to measure contact with the tissue, measure the electrical activity of the tissue (e.g., electrogram), or a combination thereof.

[0333] In some embodiments, the sensor 226 can be formed as a rivet that can be fixed to the deformable portion 242 through the aperture 237. A grommet 239 can be disposed in the aperture 237, between the sensor 226 and the deformable portion 242 of the ablation electrode 224. The grommet 239 can be formed of, for example, an electrically insulating material (e.g., any of a variety of different biocompatible polymers) that is spaced between the sensor 226 and the deformable portion 242 of the ablation electrode 224. In this manner, the grommet 239 can electrically isolate the sensor 226 from the deformable portion 242 of the ablation electrode 224. Additionally or alternatively, the grommet 226 can be formed of a pliable material to facilitate, for example, press-fitting the grommet 239 and the sensor 226 through the aperture 237.

[0334] Generally, the grommet 239 can reduce the likelihood that mounting the sensor 226 in the aperture 237 will interfere with the operation of the sensor 226. For example, the grommet 239 can facilitate mounting the sensor 226 to the deformable portion 242 of the ablation electrode 224 without physically modifying the sensor 226 (e.g., drilling a hole).

[0335] Reference now Fig.26 , the finite difference method is used to simulate the ablation electrode 224 ( Fig.21 ). In the simulation, the ablation electrode 224 is assumed to have a uniform voltage (e.g., 1 V) with the dielectric set to a uniform resistivity. The return electrode is assumed to be the edge of the domain and is set to another uniform voltage (e.g., 0 V). It can be considered that the change in simulated current density along a trajectory at a fixed distance away from the outer surface of the deformable portion 242 (shown as an arc extending from position 0 to position 450) is representative of the actual change in current density along the corresponding trajectory of the deformable portion 242.

[0336] Reference now Fig.26 and 27 , the simulated current density through the deformable portion 242 varies by less than about ±10% along a trajectory 1 mm away from the outer surface of the deformable portion 242 in the uncompressed state. Therefore, the current density at a fixed distance near the deformable portion 242 in the uncompressed state is considered to be relatively uniform. Therefore, more generally, the current density near the surface of the deformable portion 242 is generally insensitive to the orientation of the deformable portion 242 relative to the tissue. In addition, assuming that the deformable portion 242 in the expanded state is larger than the catheter shaft 222 ( Fig.21 ), the deformable portion 242 can reliably deliver a wide lesion in any of a variety of different orientations relative to the tissue. This can be useful, for example, to reduce treatment time and / or increase the likelihood that the ablation energy applied is sufficient to treat a targeted arrhythmia.

[0337] Although Fig. 27 The results shown are based on simulations using the finite difference method, but the general observations drawn from these simulations are supported by the experimental results described below.

[0338] Fig.28 The ablation electrode 224 ( Fig.21 ) were applied to a chicken breast. Each lesion was made in a chicken breast and 0.45% saline solution at body temperature. For each lesion, the ablation electrode 224 ( Fig.21 ) was placed in contact with the chicken breast meat with a force of 10 g and 8 mL / min of irrigation liquid was used. For each ablation, the deformable portion 242 ( Fig.21 ) 2 amps were delivered to the tissue for 10 seconds. A ruler was used to measure the depth of tissue fading from pink to white to determine the depth of injury.

[0339] With the deformable portion 242 ( Fig.21 ) produces five lesions, in which the catheter shaft 222 ( Fig.21 ) is perpendicular to the chicken breast, and five lesions are produced using the deformable portion 242 in a transverse orientation, which is perpendicular to the axial orientation. Fig.28 As shown, although different orientations are used to generate lesions, the lesion depths are similar, with the lesion depth variation being less than about ±20%, indicating that the amount of energy used to ablate tissue is similar in both orientations. This experimental finding is consistent with the simulation results. That is, corresponding to the deformable portion 242 ( Fig.21) and tissue at multiple different angles of lesion has a similar depth at each of the multiple different angles. This uniform distribution of current density can help control lesion size, which is particularly useful for ablating thin tissue.

[0340] Although the central electrode has been described as being disposed on the irrigation element, it should be understood that the central electrode may additionally or alternatively be located at any of a variety of different locations within the deformable portion of the ablation electrode. Fig.21 The central electrode 235 in the catheter shaft may be disposed on the distal portion of the catheter shaft. Additionally or alternatively, an irrigation element (e.g. Fig.21 The flushing element 228 in the embodiment can also be used as the center electrode itself. Thus, for example, the flushing element can be at least partially formed of a conductive material and used as a reference electrode, a drive / ground electrode, or a combination thereof.

[0341] Although the ablation electrode has been shown and described as including certain generally spherical deformable portions, it should be understood that the generally spherical deformable portion as described herein may include a deformable portion in an uncompressed state having at least one hemisphere (e.g., at least one distal hemisphere) that is located within a range of greater than about ±1 mm or ±25% of the nominal radius from the center point. Thus, for example, referring now to Fig.29 , ablation electrode 324 can have a deformable portion 342 having a distal region 344 and a proximal region 346. Unless otherwise specified or clear from the context, ablation electrode 324 should be understood to be usable in place of or in addition to any one or more of the ablation electrodes described herein. Thus, by way of example and not limitation, unless otherwise specified or clear from the context, ablation electrode 324 should be understood to be usable in place of ablation electrode 124 ( Figure 2 ), ablation electrode 124'( Fig.18 ), ablation electrode 124″ and ablation electrode 224 ( Fig.21 )

[0342] Typically, the deformable portion 342 can be generally spherical in an uncompressed state. That is, in an uncompressed state, the distal region 344 of the deformable portion 342 can be at least a hemisphere that is located within a range greater than about ±1 mm from the center point "P" or ±25% of the nominal radius "R". Fig.29 In the figure, for the sake of clarity, the extent of the hemisphere of the deformable portion 342 is shown only in two dimensions. However, considering the three-dimensional extent of the deformable portion 342, it should be understood that Fig.29 The relationships shown in apply to three dimensions.

[0343] In some embodiments, in the uncompressed state, the proximal region 346 of the deformable portion 342 may have a different shape than the distal region 344. For example, the proximal region 346 may be generally conical in the uncompressed state. As used herein, the generally conical shape of the proximal region 346 should be understood to include any one or more of a variety of different shapes for which, in the uncompressed state, the shortest distance from each point along the proximal region 346 is less than about ±1 mm from the frustum of the right cone 348. For example, the frustum of the right cone 348 may have a first base radius of about 1 mm or more and a second base radius of about 6 mm or less, the first base radius being smaller than the second base radius.

[0344] In general, it should be understood that an ablation electrode 324 having a generally spherical shape including a generally conical proximal region 346 may have any one or more advantages as described herein relative to other ablation electrodes, and thus, it should be understood that advantages may be provided relative to one or more of uniform current density near the outer surface of the ablation electrode 324 and repeatable placement of struts, holes and / or sensors as the deformable portion 342 moves from a compressed state to an uncompressed state. Further, or alternatively, an ablation electrode 324 having a generally spherical shape may cause less trauma to tissue (e.g., when contact exists between the deformable portion 342 and tissue of the heart) compared to other shapes. Additionally, or alternatively, in the event that the maximum radial dimension of the ablation electrode 324 is greater than the maximum radial dimension of the distal portion of the catheter shaft, the proximal region 346 being formed as a generally conical shape may facilitate proximal movement of the ablation electrode 324. That is, continuing with this example, the generally conical shape of the proximal region 346 can provide less resistance to proximal movement into or within, for example, a heart, a blood vessel, a sheath, an insertion cuff, or a combination thereof, compared to other shapes.

[0345] Although the ablation electrode has been described as including a deformable portion, other configurations of the ablation electrode are also possible, additionally or alternatively. For example, the ablation electrode may include a plurality of struts (e.g., any of the struts described herein) defining a plurality of apertures, the struts forming a substantially rigid structure that can maintain a shape in response to a force applied to the ablation electrode. For example, the plurality of struts can form, for example, a substantially rigid structure having a maximum radial dimension that is substantially equal to a maximum radial dimension of a catheter shaft, the substantially rigid structure being coupled (e.g., directly or indirectly) to the catheter shaft. In use, one or more of an irrigation fluid and blood can flow through the apertures of the substantially rigid structure, as described with respect to any one or more of the ablation electrodes described herein. Additionally or alternatively, any one or more of the surface electrodes described herein can be carried on a substantially rigid structure, and the substantially rigid structure can be coated with any one or more of the center electrodes described herein. Thus, for example, one or more surface electrodes carried on a substantially rigid structure can cooperate with a center electrode coated by a substantially rigid structure to detect tissue contact with an anatomical structure.

[0346] The above systems, devices, methods, processes, etc. can be implemented in hardware, software, or a combination of these suitable for a particular application. Hardware can include general-purpose computers and / or special-purpose computing devices. This includes implementation in one or more microprocessors, microcontrollers, embedded microcontrollers, programmable digital signal processors or other programmable devices or processing circuits, and internal and / or external memory. This can also, or alternatively, include one or more application-specific integrated circuits, programmable gate arrays, programmable array logic components, or any other device or devices that can be configured to process electronic signals.

[0347] It should also be understood that the implementation of the above-mentioned process or device may include a computer executable code created using a structured programming language such as C, an object-oriented programming language such as C++, or any other high-level or low-level programming language (including assembly language, hardware description language, and database programming language and technology) that can be stored, compiled, or interpreted to run one of the above-mentioned devices, as well as a heterogeneous combination processor, a processor architecture, or a combination of different hardware and software. On the other hand, these methods may be embodied in a system that performs its steps, and may be distributed across devices in a variety of ways. At the same time, the process may be distributed across devices such as the above-mentioned multiple systems, or all functions may be integrated into dedicated stand-alone devices or other hardware. On the other hand, the means for performing the steps associated with the above-mentioned process may include any of the above-mentioned hardware and / or software. All of these permutations and combinations are intended to fall within the scope disclosed in this application.

[0348] The embodiments disclosed herein may include a computer program product including computer executable code or computer usable code that, when executed on one or more computing devices, performs any and / or all of the steps thereof. The code may be stored in a non-transitory manner in a computer memory, which may be a memory for program execution (e.g., a random access memory associated with a processor), or a storage device such as a disk drive, flash memory, or any other optical, electromagnetic, magnetic, infrared, or other device and combination of devices.

[0349] In another aspect, any of the above systems and methods may be embodied in a suitable transmission or propagation medium carrying the computer executable code and / or any input or output from the computer executable code.

[0350] The method steps of the implementation described herein are intended to include any suitable method for performing such method steps, consistent with the patentability of the attached claims, unless a different meaning is explicitly provided or clearly stated from the context. Thus, for example, the step of performing X includes any suitable method for causing another party (such as a remote user), a remote processing resource (e.g., a server or cloud computer), or a machine to perform the step of X. Similarly, performing steps X, Y, and Z may include any method for directing or controlling any combination of such other individuals or resources to perform steps X, Y, and Z to obtain the benefits of these steps. Therefore, the method steps of the embodiments described herein are intended to include any suitable method for causing one or more other parties or entities to perform steps consistent with the patentability of the attached claims, unless a different meaning is explicitly provided or clearly stated from the context. Such parties or entities do not need to be directed or controlled by any other party or entity, nor do they need to be located in a specific jurisdiction.

[0351] It should also be understood that the above method is provided as an example. In the absence of explicit contrary instructions, the disclosed steps may be modified, supplemented, omitted and / or reordered without departing from the scope of the present application.

[0352] It should be understood that the above methods and systems are described by way of example and not limitation. Many variations, additions, omissions and other modifications are apparent to those of ordinary skill in the art. In addition, the order or representation of the method steps in the above description and drawings is not intended to require the order in which the steps are performed, unless a specific order is explicitly required or is clearly indicated from the context. Therefore, although specific embodiments have been shown and described, it is apparent to those skilled in the art that various changes and modifications may be made in form and detail without departing from the spirit and scope disclosed herein, and are intended to form a part of the present invention as defined by the appended claims, which will be interpreted in the broadest sense permitted by law.

Claims

1. A catheter, comprising: a catheter shaft having a proximal portion and a distal portion, the catheter shaft defining a lumen extending from the proximal portion to the distal portion; an irrigation element at the distal end portion of the catheter shaft, the irrigation element defining irrigation ports in fluid communication with the lumen, and wherein the irrigation ports are circumferentially and axially spaced apart along the irrigation element; and an ablation electrode at the distal portion of the catheter shaft, wherein the ablation electrode comprises: a coupling portion attached to the catheter shaft, and an expandable portion surrounding the irrigation element, wherein the expandable portion includes a plurality of conductive struts surrounding the irrigation element, and wherein a distal portion of the irrigation element terminates proximal to a distal end of the expandable portion of the ablation electrode, wherein in the absence of external forces applied to the ablation electrode, the expandable portion assumes a substantially spherical shape, wherein the distal end of the expandable portion is positioned about a central axis defined by the catheter shaft, and Wherein the irrigation port of the irrigation element is positioned to direct fluid toward an interior portion of the ablation electrode, including distally toward the distal end of the expandable portion of the ablation electrode.

2. The catheter of claim 1 , wherein at least some of the irrigation ports have a maximum dimension, and in the absence of external force applied to the ablation electrode, a ratio of the maximum dimension of each irrigation port to a corresponding vertical distance between the irrigation port and the inner portion of the ablation electrode is greater than 0.02 and less than 0.

2.

3. The catheter according to any one of claims 1-2, wherein the total area of ​​the flushing ports is greater than 0.05 mm 2 and less than 0.5mm 2 .

4. The catheter according to any one of claims 1-2, wherein the ablation electrode is coated with the irrigation element.

5. The catheter of claim 4, wherein a volume defined by the interior portion of the ablation electrode in the expanded state is greater than a volume defined by the irrigation element in the expanded state.

6. The catheter according to claim 4, wherein: In the absence of an external force applied to the ablation electrode, the ablation electrode includes a portion contained between a first radius and a second radius, the first radius and the second radius being within 30% of each other.

7. The catheter according to claim 1, wherein: In the absence of an external force applied to the ablation electrode, the ablation electrode includes a generally conical proximal region.

8. The catheter of claim 4, wherein the irrigation element is expandable.

9. The catheter of claim 8, wherein the irrigation element comprises an ellipsoidal portion in the expanded state.

10. The catheter according to any one of claims 1-2, wherein: At least a portion of the irrigation port is arranged to direct fluid in a distal direction relative to the ablation electrode, and at least a portion of the irrigation port is arranged to direct fluid in a proximal direction relative to the ablation electrode.

11. The catheter of any one of claims 1-2, wherein the irrigation element comprises one of a non-compliant balloon or a semi-compliant balloon.

12. The catheter according to any one of claims 1-2, wherein the irrigation element is a resilient expandable structure.

13. The catheter of any one of claims 1-2, wherein the irrigation element comprises a porous membrane.

14. The catheter of any one of claims 1-2, wherein the irrigation element comprises an open cell foam material.

15. The catheter of any one of claims 1-2, wherein the irrigation element is expandable to have a cross-sectional dimension that is greater than a cross-sectional diameter of the catheter shaft.

16. The catheter of any one of claims 1-2, wherein the irrigation element is electrically isolated from the ablation electrode.

17. The catheter of any one of claims 1-2, wherein the irrigation element is electrically isolated from the ablation electrode within a predetermined frequency range.

18. The catheter of any one of claims 1-2, further comprising a central electrode disposed along the irrigation element.

19. The catheter of any one of claims 1-2, wherein the irrigation element is thermally isolated from the ablation electrode.

20. The catheter of any one of claims 1-2, further comprising a thermocouple disposed along the irrigation element.

21. The catheter of any one of claims 1-2, further comprising a handle coupled to the proximal portion of the catheter shaft, the handle comprising a drive portion configured to drive deflection of the catheter shaft.

22. The catheter of any one of claims 1-2, further comprising a plurality of sensors, wherein the ablation electrode comprises a deformable portion, and the plurality of sensors are supported on the deformable portion of the ablation electrode.

23. The catheter of claim 22, wherein at least one of the sensors is movable into contact with the irrigation element when an external force applied along the deformable portion of the ablation electrode exceeds a threshold force.

24. The catheter of claim 23, wherein none of the plurality of sensors is in contact with an irrigation element when the deformable portion of the ablation electrode is in an uncompressed state.

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