JP5460610B2 - Perfusion ablation catheter with magnetic tip for magnetic field control and guidance - Google Patents

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application claims priority to US patent application Ser. No. 11 / 953,615 filed Dec. 10, 2007 (the '615 application). In addition, this application is a continuation of US patent application No. 11 / 434,200 ('200 application) filed on May 16, 2006, which is a continuation of US patent application filed on November 30, 2007. No. 11 / 948,362 ('362 application) is also a continuation of the entire disclosure of which is hereby incorporated by reference.

  The present invention generally relates to ablation catheters and electrode assemblies. More particularly, the present invention relates to an ablation electrode assembly for use in a human body having a magnetic tip for magnetic field control and guidance, a perfusion mechanism to a target area, and mapping characteristics.

  Electrophysiology catheters are used for an ever-increasing procedure. For example, catheters are used for diagnosis, therapy and ablation procedures, to name a few. Typically, the catheter is routed through the patient's vasculature to a target site, eg, a site within the patient's heart.

  The catheter typically holds one or more electrodes that can be used for ablation, diagnosis, and the like. There are a number of methods used for ablation of the desired area, including, for example, radio frequency (RF) ablation. RF ablation is accomplished by ablating tissue at the target site by transmitting radio frequency energy through the electrode assembly to the desired target area.

  Because RF ablation can generate significant heat that can cause protein denaturation, blood clotting, excessive tissue damage such as steam pop, tissue charring, etc. if not carefully monitored and / or controlled, the temperature of the ablation assembly It is desirable to monitor. It is further desirable to include a perfusion mechanism to a specific target area using a biocompatible fluid such as saline. This perfusion reduces or avoids excessive and undesired tissue damage, as well as blood clotting and related problems. However, the introduction of this perfusion solution may interfere with the ability to accurately monitor and / or control the temperature of the ablation assembly during use.

  There are usually two types of perfusion electrode catheters, open and closed perfusion catheters. Closed ablation catheters typically circulate a cooling fluid within the internal cavity of the electrode. On the other hand, open ablation catheters typically transport cooling fluid through open orifices on the electrodes. Examples of these known catheters include THERMOOLOOL ™ catheters that are marketed and sold by Biosense-Webster. Current open perfusion ablation catheters use the electrode's internal cavity or distal member as a manifold for dispensing saline. Thus, saline flows directly through the open orifice of the distal electrode member. This direct flow through the distal electrode tip reduces the temperature of the distal tip during surgery, making accurate monitoring and control of the ablation process more difficult.

  In these open perfusion electrode catheters, it has been found advantageous to insulate the perfusion channel from the ablation electrode. One such example was titled “Saline-Irrigated Radiofrequency Ablation Electrode with Electrode Cooling” by Dr. Wittkampf and Dr. Nakagawa in or before March 2005. The entire contents of which are incorporated herein by reference. Similarly, the entire contents of PCT International Publication No. WO05 / 048858 published on June 2, 2005 are also incorporated herein by reference.

  Recently, a magnetic system has been proposed in which a magnetic field generated by one or more electromagnets is used to guide and advance a catheter having a magnet at the tip. For example, U.S. Patent Application Publication No. 2007/0016006 describes an apparatus and method for guiding, maneuvering and advancing an invasive device, an apparatus and method for accurately controlling the positioning of an invasive device for magnetic field and magnetic field gradient positioning, As well as an apparatus and method for providing a magnetic field configured to push / pull, bend / rotate, and preferably an excess that may be dangerous to medical personnel and may destroy other equipment The device can be aligned to the distal end of the catheter tip to achieve the function of the device to control controlled movement and magnetic field properties in three-dimensional space without using large power and magnetic field strength Discloses an apparatus and method. The entire disclosure of US Patent Application Publication No. 2007/0016006 is incorporated herein by reference.

  Embodiments of the present invention provide a perfusion catheter having a magnetic tip that is configured to provide better electrode surface cooling and more accurate electrode tip temperature measurement and that can be magnetically guided and controlled. provide. The perfusion catheter may further include one or more monitoring or measurement electrodes for mapping and the like. The perfusion fluid is delivered to the target area where clotting is more likely to occur in order to minimize blood clotting and its associated problems. In some embodiments, the present invention improves the operation, temperature response, temperature monitoring and / or control mechanisms of the ablation assembly while perfusing the target area, thereby reducing unwanted unwanted tissue damage and blood clotting. Providing a combined perfusion ablation electrode assembly with the advantage of preventing further provides significant improvements over known perfusion catheters, including those published by Wittkampf and Nakagawa et al.

  The present invention guides the magnetic tip of the perfusion catheter and pump assembly and RF generator assembly, and electrode assembly, designed to minimize blood clotting and unwanted tissue damage while monitoring and controlling the ablation process. And an improved perfusion ablation electrode assembly and method useful in combination with a catheter guidance control and imaging system designed to control and perform mapping and other imaging functions.

  According to one aspect of the present invention, a perfusion ablation electrode assembly for use with a perfusion catheter device comprises at least one fluid passage having an outlet disposed on an outer surface of the electrode assembly, a permanent magnet, and at least a permanent magnet. It includes a shield that is separated from one passageway and the exterior and that is substantially less oxidized than a permanent magnet, and an electrode having an external electrode surface.

  In some embodiments, the electrode includes a conductive material that forms at least a portion of the shield and is substantially less oxidized than the permanent magnet. The conductive material is selected from the group consisting of platinum, gold, tantalum, iridium, stainless steel, palladium and mixtures thereof, and the conductive material is made of a biocompatible material that is substantially less oxidized than a permanent magnet. Is plated on a substrate. The shield includes one or more materials selected from the group consisting of silicone, polyimide, platinum, gold, tantalum, iridium, stainless steel, palladium, and mixtures thereof. As an example, the permanent magnet includes NdFeB. At least one mapping electrode is spaced proximally from an electrode that is an ablationable distal electrode.

  In a specific embodiment, the electrode is disposed at a distal portion of the electrode assembly and includes an external electrode surface, the electrode assembly having at least one fluid outlet disposed on an outer surface of the proximal portion. It further includes a proximal portion including a proximal passage. The proximal portion includes a material that is non-conductive and has a lower thermal conductivity than the material of the electrode. At least one proximal passage extends toward the electrode at an acute angle with respect to the longitudinal axis of the proximal portion. The proximal portion comprises a non-conductive material, the outer surface of the proximal portion and the outer electrode surface of the electrode at the distal portion meet at the intersection, and at least one proximal passage allows fluid flow through the outlet It is comprised so that it may guide toward the area | region adjacent to an intersection part. The permanent magnet is disposed within the distal portion and the electrode assembly further includes at least one temperature sensor disposed within the permanent magnet. The electrode includes an external electrode surface, and the electrode includes at least one fluid electrode passage having an outlet disposed on the external electrode surface. At least one electrode passage is thermally isolated from the distal member by a low thermal conductivity material that has a lower thermal conductivity than the electrode material.

  In some embodiments, the permanent magnet includes an annular permanent magnet having an axial opening that allows fluid flow to at least one electrode passage, and the electrode assembly is annular to at least one electrode passage. A fluid cavity extending into the axial opening of the permanent magnet. The fluid cavity includes a stainless steel mesh polyimide that forms part of the shield, and the electrodes form another part of the shield. The shield includes a silicone seal that prevents fluid from reaching the annular permanent magnet through the junction of the electrode and the fluid cavity. The electrode is disposed at a distal portion of the electrode assembly, and the electrode assembly further includes a proximal portion including at least one fluid proximal passage having an outlet disposed on an outer surface of the proximal portion. The proximal portion includes a non-conductive material. The outer surface of the proximal portion and the outer electrode surface of the electrode at the distal portion meet at the intersection. The at least one proximal passage is configured to direct fluid flow through the outlet to an adjacent region of the intersection.

  In accordance with another aspect of the present invention, a perfusion ablation electrode assembly for use with a perfusion catheter device has a permanent magnet and an outlet disposed on an outer surface of the electrode assembly and extends at least within the permanent magnet. One fluid passage, an inner shield that separates the permanent magnet from at least one passage, which is substantially less oxidized than the permanent magnet, and a permanent magnet that separates the permanent magnet from the outside and substantially less oxidizing than the permanent magnet Including external shield.

  In some embodiments, the inner shield includes a fluid cavity that supplies fluid to at least one passage. The electrode assembly includes an electrode having an outer electrode surface and forming at least a portion of the outer shield. The electrode is disposed at a distal portion of the electrode assembly, the electrode assembly further including a proximal portion having a non-conductive material, the proximal portion forming at least a portion of the inner shield.

  According to another aspect of the invention, the catheter includes a shaft and a perfusion ablation electrode assembly coupled to the distal end of the shaft. The perfusion ablation electrode assembly is substantially more than a permanent magnet that separates the permanent magnet from the at least one passage and the exterior, with at least one fluid passage having an outlet disposed on the outer surface of the electrode assembly. It has a shield that is difficult to oxidize and an electrode that has an external electrode surface.

  In some embodiments, the catheter further includes a second permanent magnet disposed near the distal end of the shaft and spaced from the permanent magnet in the perfusion ablation electrode assembly.

  The above and other aspects, features, details, utilities and advantages of the present invention will become apparent upon reading the following description and claims, and upon reviewing the accompanying drawings.

2 is an isometric view of an ablation electrode assembly according to one embodiment of the present invention in combination with a perfusion catheter assembly operably connected to an RF generator assembly and a pump assembly. FIG. FIG. 3 is an enlarged isometric view of an ablation electrode assembly according to one embodiment of the present invention operatively connected to a perfusion catheter assembly. FIG. 4 is a cross-sectional view of the ablation electrode assembly of FIG. 2 taken along line 4-4 of FIG. 6 is a cross-sectional view of an ablation electrode assembly according to another embodiment of the present invention. FIG. 6 is a cross-sectional view of an ablation electrode assembly according to another embodiment of the present invention. FIG. 6 is a cross-sectional view of an ablation electrode assembly according to another embodiment of the present invention. FIG. 1 is a perspective view of a magnet structure of a catheter guidance control and imaging (CGCI) system. FIG. It is a perspective view of the right side part of CGCI shown in the state where the hydraulic drive core was extended. It is a perspective view of the right side part of CGCI shown in the state where the hydraulic drive core was retracted. 1 is a system block diagram of a surgical system including an operator interface, a catheter guidance system, and surgical equipment. 1 is a block diagram of an imaging module used in a CGCI surgical procedure including a catheter guidance system, a radar system, a Hall effect sensor, and a hydraulically driven core extension mechanism. FIG. 1 is a first perspective view of a catheter assembly. FIG. FIG. 10 is a second perspective view of the catheter assembly. FIG. 7 is a side view of the apparatus of FIG. 6. FIG. 7 is a bottom view of the apparatus of FIG. 6. FIG. 7 is an isometric view of the apparatus of FIG. 6 in an open mode with the left and right clusters separated. It is a side view of the structure shown in FIG. It is a bottom view of the structure shown in FIG. FIG. 11 is an end view of the configuration shown in FIG. 10. 1 is a block diagram of one embodiment of a CGCI device having a magnetic sensor. FIG.

BACKGROUND OF THE INVENTION In general, the present invention relates to perfusion ablation electrode assemblies and methods for making and using such perfusion ablation electrode assemblies. For purposes of this description, similar aspects among the various embodiments described herein will be referred to with the same reference numerals. However, it will be appreciated that the structure of the various aspects may vary between the various embodiments.

  As shown in FIG. 1, the ablation electrode assembly facilitates ablation procedure surgery by monitoring the pump assembly 15 and any number of selected variables (e.g., ablation electrode temperature, ablation energy, and assembly position) Includes a portion of a perfusion ablation catheter assembly 12 operatively connected to an RF generator assembly 14 useful for assisting in the operation of the assembly during use and providing the necessary energy source delivered to the electrode assembly 10. You may go out. Although this embodiment describes an RF ablation electrode assembly and method, the present invention is equally applicable to any number of other ablation electrode assemblies where the temperature of the device and target tissue region is a factor during the procedure. It is assumed that

  FIG. 1 shows a general perfusion ablation catheter assembly having an RF generator assembly 14 and a fluid pump assembly 15 operatively connected to a perfusion catheter assembly 12 operably mounted with a perfusion electrode assembly 10 according to the present invention. It is a perspective view. The structural and functional characteristics of catheter assembly 12, RF generator assembly 14 and pump assembly 15 are well known to those skilled in the art. For example, the RF generator assembly may be an IBI-1500T cardiac ablation RF generator available from Irvine Biomedical, Inc., Irvine 92614, California. The RF generator assembly can also be any other, including, for example, one of the Stockert RF generators available from Biosense or the Atakr® series RF generators available from Medtronic. It may be a known assembly. The pump assembly may be any known assembly, including a fixed displacement rolling pump, a variable displacement syringe pump, and any other pump assembly known to those skilled in the art. 2-5, described in detail below, illustrate various embodiments of a perfusion ablation electrode assembly 10 according to the present invention.

  FIG. 2 is an isometric view of the ablation electrode assembly 11 connected to a perfusion ablation catheter assembly 12 having a fluid transport tube 16 therein. Ablation electrode assembly 11 generally includes perfusion member 20 and ablation electrode member 18. The orientation of the members 18, 20 is such that the ablation electrode assembly 18 is located at the distal end of the assembly with the perfusion member 20 located at the proximal end of the assembly, but the orientation is reversed. It is envisaged to obtain. The proximal member 20 has at least one passage 24 (see FIG. 3) and at least one outlet 22 for transporting fluid to the target tissue region and outside the electrode assembly 11. The distal member 18 further includes at least one temperature sensing mechanism 26 (see FIG. 3) disposed therein and operatively connected to the RF generator assembly 14. The distal member 18 is composed of any electrically conductive and potentially thermally conductive material known to those skilled in the art for transporting ablation energy to the target tissue region. Examples of conductive materials include gold, platinum, iridium, palladium, tantalum, stainless steel, and any mixture thereof. In addition, there are multiple electrode designs envisioned within the scope of the present invention, including tip electrodes, ring electrodes, and any combination thereof.

  In general, according to the embodiments described herein, the fluid passage (s) 24 and the outlet (s) 22 are separated by at least one low thermal conductivity material by the distal member 18, and consequently Separated from the temperature sensing mechanism 26. The low thermal conductivity material provides a heat transfer between the passage (s) 24 and the distal member 18 of greater than about 10%, more preferably greater than about 25%, as measured by methods known to those skilled in the art. A material with reduced physical properties. In certain embodiments, materials that reduce heat transfer by more than about 75% have performed favorably. Low thermal conductivity material reduces heat transfer by less than about 10% when the remaining structural components are selected with suitable properties and sensitivity to maintain proper monitoring and control of the process It is further envisioned that it may have physical properties that allow it to. Thus, although these properties are preferred, the low thermal conductivity material may be any material known to those skilled in the art that is consistent with the spirit of the invention. Examples of low thermal conductivity materials useful in combination with the present invention include high density polyethylene (HDPE), polyimides, polyaryl ether ketones, polyether ether ketones, polyurethane, polypropylene, oriented polypropylene, polyethylene, crystallization Examples include, but are not limited to, plastics such as polyethylene terephthalate, polyethylene terephthalate, polyester, ceramics and acetal, and mixtures thereof.

  As shown in more detail for the specific embodiments below, the low thermal conductivity material may be a proximal member 20 or a distal member 18, a material different from the proximal member 20 and the distal member 18, or any of them. It may be a material including a combination. Further, the passage (s) 24 and the outlet (s) 22 defined by the proximal member 18 (proximal member 20) are longitudinally from the end 46 (see FIG. 3) of the distal member 18. It may be separated, thereby providing the advantage of isolating the passage (s) 24 from the temperature sensor (s) 26 to improve temperature monitoring of the target area to be ablated during surgery. Separation of the low thermal conductivity material and the temperature sensing mechanism 26 located near the end 46 of the distal member 18 individually and in concert, the temperature sensing mechanism (s) 26 in the distal member 18. To the effect of the low temperature of the fluid transported through the passage (s) 24 and the outlet (s) 22. (1) To minimize coagulation and unwanted tissue damage by separating the passage (s) 24 and the outlet (s) 22 from the distal member 18, and more particularly from the temperature sensing mechanism 26. Effectively perfuse the electrode assembly 11 and the target tissue region, and (2) facilitate the two purposes of effectively controlling the operation of the ablation electrode assembly 11 according to the object of the present invention.

  FIG. 3 is a cross-sectional view of one embodiment of the ablation electrode assembly 11. Ablation electrode assembly 11 is connected to a perfusion catheter assembly 12 having a fluid transport tube 16 and a catheter shaft 17. Ablation electrode assembly 11 includes a proximal member or manifold 20, a distal member 18, and a temperature sensing mechanism 26 operably connected to RF generator assembly 14 (see FIG. 1). In this embodiment, the proximal member 20 itself is made of a low thermal conductivity material that functions to insulate the perfusion fluid from the rest of the assembly 11. Preferably, the proximal member 20 is made of a low thermal conductivity polymer, more preferably a polyetheretherketone (“PEEK”) due to the combination of thermal and physical properties of the material. Another possible material is Ultem® polyetherimide. The proximal member 20 is configured to receive the fluid conduit 16 of the catheter assembly 12 and is axially directed from the central axis 28 of the assembly 11 toward the outer portion of the proximal member 20 that terminates at the corresponding outlet 22. A plurality of extending passages 24 (eg, 4-8 passages) are included. Preferably, the plurality of passages 24 are evenly distributed around the proximal member 20 in order to evenly distribute the fluid outside the target tissue region and the assembly 11. The passage 24 may be a single annular passage or a plurality of separate passages uniformly distributed around the proximal member 20. In this embodiment, the passage 24 may be positioned at an acute angle with respect to the longitudinal axis 28 of the assembly 11. During surgery, fluid is pumped through the transport tube 16 and through the passage 24 and the outlet 22 where the fluid contacts the target tissue region and the outer portion of the ablation electrode assembly 11.

  In this embodiment, the fluid transport tube or passage 24 extends at an angle less than substantially perpendicular to the longitudinal axis 28. By setting the passage 24 at an angle away from vertical but less than parallel, further assists in transporting fluid to the target tissue region, further reducing the risk of fluid coagulation during an ablation procedure, and an ablation assembly during surgery 11 measurement and control can be improved. More particularly, the passage 24 is oriented to direct perfusion fluid flow to a target region adjacent, preferably directly adjacent, the intersection of the proximal member 20 and the distal member 18. Blood clotting is a target region due to a sharp rise in RF intensity, material discontinuities, and potential geometric discontinuities caused by poor manufacturing when joining proximal member 20 and distal member 18 together. Is likely to occur. In a specific embodiment, the passage 24 extends at an angle of about 20 ° to about 70 °, preferably about 30 ° to about 60 °, more preferably about 30 °. It is also envisioned that the passages may be further angled in the second dimension such that the passages and orifices are configured to supply fluid spirally or spirally to the exterior of the assembly. This configuration also serves to keep the fluid in close proximity to the electrode assembly, thereby further preventing clotting during surgery.

  The distal member 18 of the ablation electrode assembly 11 has a generally cylindrical shape that terminates in a circular end, which may be a hemispherical end or a non-spherical end. The distal member 18 includes a permanent magnet 48 that is at least partially encased in a distal electrode shell 50 and an electrode anchor 52. Permanent magnet 48 desirably has a strong magnetic field such that only one such permanent magnet is required for field control and guidance of the catheter tip (instead of a plurality of magnets spaced apart from each other). Manufactured with NdFeB. In other embodiments, other rare earth permanent magnets with similar characteristics may be used. Additional materials may be considered if more than one permanent magnet is used. The permanent magnet 48 usually has a length in the longitudinal direction of about 2 mm or more and about 6 mm or less, typically about 4 mm. The distal electrode shell 50 provides most of the outer surface of the distal electrode. Electrode anchor 52 is coupled to proximal member 20 and connected to a power line or power cable, such as RF wire 54. The electrode anchor 52 may be connected to the proximal member 20 by any known mechanism including adhesives, press-fit configurations, snap-fit configurations, and the like. The inner tube 56 is connected to the electrode anchor 52 and / or the proximal member 20 to accommodate the power line 54 and the temperature sensor conductor for the temperature sensor 26. Because the temperature sensor 26 is embedded in the permanent magnet 48, the permanent magnet material is preferably highly thermally conductive (eg, NdFeB) so that the temperature sensor 26 can accurately measure the temperature of the distal electrode. It is.

  In the illustrated embodiment, the distal electrode shell 50, electrode anchor 52 and inner tube 56 form a shield that prevents the permanent magnet 48 from being perfused and / or exposed to body fluids, which shield the permanent magnet 48. It includes an inner shield that includes a passage 24 that separates from the perfusion fluid, and an outer shield that separates the permanent magnet 48 from the outside. Since the permanent magnet 48 is very susceptible to oxidation, any contact between the permanent magnet and the liquid is undesirable. This is because the oxidation of the permanent magnet 48 can cause corrosion problems. The shield prevents such contact from occurring. The shielding material is less oxidizable than the permanent magnet 48, or preferably substantially less oxidizable. For example, the oxidation rate of the shield material is less than about 50%, more preferably less than about 20%, and most preferably less than about 5% of the oxidation rate of the permanent magnet. Distal electrode shell 50 and electrode anchor 52 are made of a conductive material such as platinum, gold, tantalum, iridium, stainless steel, palladium, tantalum and mixtures thereof. The selected conductive material is preferably biocompatible. In some embodiments, the biocompatible conductive material is plated on a copper or beryllium copper substrate to improve the biocompatibility of the distal electrode shell 50 and electrode anchor 52. The electrode anchor 52 may be laser welded to the distal electrode shell 50. The inner tube 56 may be made of silicone, polyimide, stainless steel mesh polyimide, or the like. The inner tube 56 may be thermally bonded or molded to the platinum anchor 52. In another embodiment, the distal electrode shell 50 and the electrode anchor 52 form a complete shield around the permanent magnet 48 without the need for an inner tube 56 that separates the permanent magnet 48 from the perfusion fluid flow.

  Proximal member 20 is preferably made of a low thermal conductivity material (as described above) having a thermal conductivity that is lower, more preferably substantially lower than the thermal conductivity of the material of distal member 18. Proximal passage 24 does not contact any interior of distal member 18. In this way, the perfusion fluid flowing in the proximal passage 24 causes the electrode of the distal member 18 to have a distance and low conductivity material that allows the temperature sensor 26 to more accurately measure the temperature of the distal electrode. And substantially insulated from the temperature sensor. The proximal member may be made of a variety of materials having insulating properties such as, for example, acetal, polyetheretherketone (PEEK), and high density polyethylene (HDPE), and other materials having the above low thermal conductivity. Good.

  One or more monitoring or measuring electrodes may be provided in the catheter assembly 12 for mapping or other monitoring or measuring functions. FIG. 3 shows two monitoring electrodes 58, 59 that are ring electrodes spaced from the distal electrode 18. In order to facilitate positioning and location of the catheter tip in the mapping system, the position of each electrode is determined. Calibration of the positioning system is accomplished by two monitoring electrodes 58, 59 separated by a known interelectrode distance or by a distal electrode 18 and one monitoring electrode (58 or 59) separated by a predetermined distance. . In use, a voltage is sensed between one electrode on the catheter assembly 12 (usually the distal electrode 18) and a reference electrode on the patient's body (preferably a surface electrode on the patient's skin). For a catheter procedure that ultimately performs ablation, sensing is performed to collect data about the heart, such as the location of the arrhythmia lesion. Such data collection techniques are well known in the art. The location information is determined based on calibration (see, eg, US Pat. Nos. 5,697,377 and 5,983,126, the entire disclosure of which is hereby incorporated by reference). ), Sensed information and location are stored and / or mapped.

  FIG. 4 is a cross-sectional view of another embodiment of the ablation electrode assembly 61. Ablation electrode assembly 61 is connected to a perfusion catheter assembly 62 having a fluid transport tube or cavity 64 and a catheter shaft 66. The ablation electrode assembly 61 includes a distal member 68, a permanent magnet 70 disposed proximal to the distal member 68, and a shell 72 surrounding the outer and proximal surfaces of the permanent magnet 70. Distal member 68 has a generally cylindrical shape that terminates in a circular end, which may be a hemispherical end or a non-spherical end. The permanent magnet 70 is an annular member having an inner surface covered with a part of the fluid transport pipe 64. Permanent magnet 70 desirably has a strong magnetic field such that only one such permanent magnet is required for magnetic field control and guidance of the catheter tip (instead of a plurality of magnets spaced apart from each other). Manufactured with NdFeB. The permanent magnet 48 typically has a length in the longitudinal direction of about 2 mm or more and about 6 mm or less, typically about 4 mm. The distal member 68, shell 72 and fluid transport tube 64 form a shield that prevents the permanent magnet 70 from being exposed to liquid, and the shield separates the permanent magnet 70 from the perfusion fluid flowing within the catheter assembly 62. It includes an outer shield that separates the inner shield and the permanent magnet 70 from the outside. Further, to prevent any liquid from reaching the permanent magnet 70 via the junction of the distal member 68 and the fluid transport tube 64, the proximal surface of the distal member 68 and the distal surface of the permanent magnet 70 Between these, a sealant 74 is preferably provided.

  Distal member 68 provides the outer surface of the distal electrode. Shell 72 may be a conductive surface to provide a further outer surface of the distal electrode. In this case, the electrode shell 72 is connected to a power cable or power line such as the RF wire 76. One or more temperature sensors 77 may be provided in the distal member 68 and a temperature sensor conductor 78 for the temperature sensor 77 extends proximally within the catheter shaft 66.

  Since the permanent magnet 70 is very susceptible to oxidation, any contact between the permanent magnet and the liquid is undesirable. The shield prevents such contact from occurring. The shield material is less susceptible to oxidation than the permanent magnet 70, and preferably is substantially less likely to oxidize. Distal member 68 and electrode shell 72 are made of a conductive material such as platinum, gold, tantalum, iridium, stainless steel, palladium, tantalum and mixtures thereof. The conductive material selected is preferably biocompatible. In some embodiments, the biocompatible conductive material is plated onto a copper or beryllium copper substrate to improve the biocompatibility of the distal member 68 and the electrode shell 72. The fluid transport pipe 64 is non-conductive and is made of silicone, polyimide, stainless steel mesh polyimide, or the like. The electrode shell 72 is connected to the distal member 68 by laser welding or the like. Distal member 68 and electrode shell 72 form a distal electrode. The shell 72 may be connected to the catheter shaft 66 by an adhesive or the like. The fluid transport tube 64 may be connected to the shell 72, permanent magnet 70 and distal member 68 by thermal bonding, molding, adhesive, or the like.

  The fluid transport tubes 64 flow fluid through one or more distal passages 79 in the distal member 68 to their external outlets. There is preferably a central passage along the longitudinal axis of the distal member 68 and optionally further passages distributed around the central passage. The passage 79 is preferably lined with a low thermal conductivity material 75 such as polyetheretherketone (“PEEK”) which functions to insulate fluid from the material of the distal member 68 and the temperature sensor 77. Thus, since the fluid flowing in the passage 79 does not affect the measurement of the temperature sensor 77, the temperature sensor 77 can measure the temperature of the distal electrode more accurately. Preferably, additional passages are evenly distributed around the central passage in order to distribute fluid evenly outside the target tissue region and assembly 61.

  One or more monitoring or measurement electrodes may be provided in the catheter assembly 62 for mapping or other monitoring or measurement functions. FIG. 4 shows one monitoring electrode 80 that is a ring electrode spaced from the distal electrode (formed by the distal member 68 and electrode shell 72) by a known interelectrode distance for calibration. In use, a voltage is sensed between the distal electrodes (68 and 72) and a reference electrode on the patient's body (preferably a surface electrode on the patient's skin). The location information is determined based on calibration, and the sensed information and location is stored and / or mapped.

  FIG. 4A shows a perfusion catheter assembly 62A that is substantially identical to the perfusion catheter assembly 62 of FIG. The assembly 62A includes a second permanent magnet 70A disposed near the distal end of the shaft 66 and spaced from the first permanent magnet 70. In the illustrated embodiment, the second permanent magnet 70 </ b> A is an annular magnet, and is smaller and thinner than the first permanent magnet 70. The second permanent magnet 70A does not require an additional shield. This is because the second permanent magnet 70A is disposed in the space between the catheter shaft 66 and the fluid transport tube 64 without exposure to liquid. Of course, the second permanent magnet may have other configurations in different embodiments, and instead of being spaced proximally from the electrode assembly 61 within the catheter shaft 66, the perfusion ablation electrode assembly 61 It may be formed inside. Additional permanent magnets in the assembly may provide additional options for magnetic control and guidance of the catheter tip.

  FIG. 5 is a cross-sectional view of another embodiment of an ablation electrode assembly 81 connected to a perfusion catheter assembly 82. The electrode assembly 81 of FIG. 5 also includes a distal member 68, a permanent magnet 70, a shell 72 connected to the RF wire 76, a sealant 74, and a temperature sensor 77 connected to a temperature sensor conductor 78. Similar to four electrode assemblies 61. In this embodiment, the distal member 68 preferably has a central passage 79 lined with a low thermal conductivity material 75 such as polyetheretherketone (“PEEK”). The fluid transport tube 64 extends through the catheter shaft 66 to the electrode assembly 81. One or more monitoring or measuring electrodes 80 may be provided in the catheter assembly 62 for mapping or other monitoring or measuring functions.

  In FIG. 5, the ablation electrode assembly 81 includes a proximal member 84 disposed proximal to the permanent magnet 70 and the electrode shell 72. Proximal member 84 has at least one proximal passage 86 with at least one outlet 88 for transporting fluid to the target tissue region and outside electrode assembly 81. Proximal passage (s) 86 and outlet (s) 88 are separated from distal member 68 and electrode shell 72 and consequently temperature sensing mechanism 77 by at least one low thermal conductivity material. . The low thermal conductivity material may be a material that includes the proximal member 84 or the distal member 68, a material different from the proximal member 84 and the distal member 68, or any combination thereof. In this embodiment, the proximal member 84 is made of a low thermal conductivity material that functions to insulate the fluid from the rest of the assembly 81. The proximal member 84 is configured to receive the fluid tube 64 of the catheter assembly 82 and is axially from the central axis of the assembly 81 toward the outer portion of the proximal member 84 that terminates at the corresponding outlet 88. A plurality of extending proximal passages 86 (eg, 4-8 passages) are included. Preferably, the plurality of proximal passages 86 are evenly distributed around the proximal member 84 in order to distribute fluid evenly outside the target tissue region and assembly 81. Proximal passage 86 may be a single annular passage or a plurality of separate passages uniformly distributed around proximal member 84. In this embodiment, the proximal passage 86 may be located at an acute angle with respect to the longitudinal axis of the assembly 81. During surgery, fluid is pumped through the transport tube 64 through the proximal passage 86 and the outlet 88 where the fluid contacts the target tissue region and the outer portion of the ablation electrode assembly 81.

  In this embodiment, the proximal passage 86 extends at an angle that is less than substantially perpendicular to the longitudinal axis. By setting the passage 86 at an angle away from vertical but less than parallel, it further assists in transporting fluid to the target tissue region, further reducing the risk of fluid coagulation during an ablation procedure, and an ablation assembly during surgery 81 measurement and control can be improved. More particularly, the proximal passage 86 is oriented to direct perfusion fluid flow to a target region adjacent, preferably directly adjacent, the intersection of the proximal member 84 and the electrode shell 72. Blood clotting occurs in the target area due to a rapid increase in RF intensity, material discontinuities, and potential geometric discontinuities caused by manufacturing failure in joining proximal member 84 and electrode shell 72. Likely to occur. In a specific embodiment, the proximal passage 24 extends at an angle of about 20-70 °, preferably about 30-60 °, more preferably about 30 °. It is also envisioned that the proximal passage can be further angled in the second dimension such that the proximal passage and the orifice are configured to supply fluid in a spiral or spiral fashion to the exterior of the assembly. . This configuration serves to keep the fluid in close proximity to the electrode assembly, thereby further preventing clotting during surgery.

  The proximal member 84 further includes a longitudinal outlet that moves fluid through the central tube 90 to the central passage 79 of the distal member 68. The central tube 90 is non-conductive and may be made of silicone, polyimide, stainless steel mesh polyimide, or the like. Central tube 90 may be connected to electrode shell 72, permanent magnet 70, and distal member 68 by thermal bonding, molding, adhesive, or the like. Distal member 68, electrode shell 72 and central tube 90 form a shield that separates permanent magnet 70 from the perfusion fluid and the outside.

Catheter guidance control and imaging (CGCI)
An example of a system for magnetically guiding and controlling a catheter having a magnetic tip is described in US Patent Application Publication No. 2007/0016006, the entire disclosure of which is incorporated herein by reference. FIGS. 6, 7A and 7B are isometric views of a catheter guidance control and imaging (CGCI) system 1500 (FIG. 7C) having a left coil cluster 100 and a right coil cluster 101 provided on the rail 102. FIG. The rail 102 functions as a guidance adjusting device. The CGCI system workstation 1500 includes a structural support assembly 120, a hydraulic system 140 and a propulsion system 150.

  The central arc portion 106 supports the upper cylindrical coil 110, and the two short arc portions 107 and 108 support the two conical coils 115 and 116. The two short arc portions 107 and 108 are separated from the central arc portion 106 by about 35 °. The separation angle between the two short arcs is about 70 °. At the end of each arc 106, 107 and 108 is a machined block made of 1010 steel with connections that provide attachment of the coil assemblies 115, 116, 110.

  The two curved shield plates 105 form a shield for containing and forming at least part of the magnetic field. The shield 105 also provides side strength to the assembly. Base 117 houses propulsion system 150 and locking mechanism 118. In one embodiment, the plate 105 is made of steel, nickel or other magnetic material.

  In addition to FIG. 6, FIGS. 7A and 7B also show various mechanical details that form the CGCI cluster half (right electromagnetic cluster 101). The locking hole 103, the spur drive rail 104, the cam roller 118, and the solenoid locking pin 119 are configured so that a part of the CGCI can be moved along the track 102. The cluster 101 includes three electromagnets that form a magnetic circuit. The left coil 116 and the right coil 115 are mounted as shown and supported by C-shaped arms 107 and 108. The coil 110 includes a hydraulic drive core 111 supported by a stainless steel coil fixing disk 127. The coil stress relaxation disk 113 is made of Teflon (registered trademark). The coil cylinder 110 is surrounded by a coil base disk 114 made of stainless steel. The coil core 111 is driven (extended and retracted) by the hydraulic system 109. FIG. 7B shows the right coil cluster 101 with the hydraulic drive core 111 retracted through the use of a hydraulic system 109 that can cause the CGCI to form a magnetic field.

  7C illustrates an operator interface 500, a CGCI system 1500, a surgical instrument 502 (eg, catheter tip 11 of FIG. 3, catheter tip 61 of FIG. 4, catheter tip 81 of FIG. 5 or catheter tip 377 of FIG. 8A). FIG. 6 is a system block diagram of a surgical system 800 that includes one or more user input devices 900 and a patient 390. User input device 900 may include one or more joysticks, a mouse, a keyboard, and the like that allow the surgeon to provide command input to control the movement and orientation of catheter tip 377 (or tips 11, 61, 81). Virtual tip 905 and other devices can be included.

  In one embodiment, the CGCI system 1500 includes a controller 501 and an imaging synchronization module 701. FIG. 7C shows the overall relationship between the various functional units and the operator interface 500, auxiliary device 502 and patient 390. In one embodiment, the CGCI system controller 501 calculates the actual tip (AT) position of the distal end of the catheter. Using the data from the virtual tip (VT) 905 and the imaging / synchronization module 701, the CGCI system controller 501 is a position error that is the difference between the actual tip position (AP) and the desired tip position (DP). Determine. In one embodiment, the controller 501 controls the electromagnet to move the catheter tip in a selected direction to minimize position error (PE). In one embodiment, the CGCI system controller 501 provides haptic feedback to the operator by providing force feedback to the VT 905.

  FIG. 7D is a block diagram of a surgical system 503 illustrating one embodiment of a CGCI system 1500. The system 503 includes a controller 501, a radar system 1000, a Hall effect sensor array 350 and a hydraulic drive mechanism 140. In one embodiment, sensor 350 includes one or more Hall effect magnetic sensors. The radar system 1000 can be configured as an ultra-wideband radar, an impulse radar, a continuous wave (CW) radar, a frequency modulation CW (FM-CW) radar, a pulse Doppler radar, or the like. In one embodiment, the radar system 1000 uses a synthetic aperture radar (SAR) process to generate radar images. In one embodiment, radar system 1000 includes an ultra-wideband radar, such as described in US Pat. No. 5,774,091, the entire disclosure of which is incorporated herein by reference. In one embodiment, the radar 1000 is configured as a laser range finder for identifying the position of the catheter tip 377. The radar 1000 is configured to specify the position of a reference marker (standard marker) arranged on the body of the patient 390. For example, for image capture synchronization 701, data regarding the position of the reference marker can be used. The electromagnets (see FIG. 14) of the cylindrical coils 51AT and 51DT can be moved with respect to the patient 390 by the hydraulic drive operation control mechanism 140 with a motor.

  In one embodiment, the use of radar to locate the catheter tip 377 has advantages over the use of fluoroscopy, ultrasound, magnetostrictive sensors or SQUIDs. Radar can provide accurate dynamic position information that provides real-time relatively high resolution and relatively high fidelity compatibility in the presence of a strong magnetic field. Self-calibration of distance measurements can be based on time-of-flight and / or Doppler processing. Furthermore, the radar measures the catheter position without any “hard” surfaces such as the rib cage, bone structure, etc., because there is no interference with the measurement or interference with the accuracy of the measurement. Also, organ movement and deformation (eg, pulmonary dilation and rib cage deformation and diastole or systolic cardiac output) do not require adjustment or correction of radar signals. Radar can be used in the presence of motion because it can use radar burst emissions above 1 GHz at sampling rates of 50 Hz and higher while cardiac motion and catheter motion occur between 0.1 Hz and 2 Hz. it can.

  In one embodiment, the use of radar 1000 is expensive, typically fluoroscopy, ultrasound, magnetostrictive technology, or SQUID, which requires a computationally intensive process to translate the image and convert it to a coordinate data set. Reducing the need for complex image capture techniques associated with different modalities. Position data synchronization between the catheter tip 377 and the moving organ can be easily utilized by using the radar 1000. Radar 1000 can be used with phased array or synthetic aperture processing to generate detailed images of catheter positions in the body and in-body structures. In one embodiment, the radar system includes an ultra wide bandwidth (UWB) radar having a relatively high resolution sweep range gate. In one embodiment, a differential sampling receiver is used to effectively reduce ringing and other aberrations contained within the receiver by bringing the transmit antennas in close range. Similar to x-ray systems, radar systems can detect the presence of obstacles or objects located behind barriers such as bone structures. The presence of different substances with different dielectric constants such as adipose tissue, muscle tissue, water etc. can be detected and identified. The output from the radar can be correlated with similar units such as multiple catheters used in electrophysiology (EP) studies while detecting the spatial position of other catheters present in the heart lumen. Radar system 1000 can use a phased array antenna and / or SAR to generate a three-dimensional composite radar image of body structure, catheter tip and organ.

  In one embodiment, the position of the patient relative to the CGCI system (including the radar system 1000) can be determined by using the radar 1000 to identify a plurality of fiducial markers. In one embodiment, data from radar 1000 is used to position the body relative to the imaging system. Catheter position data from the radar 1000 can be superimposed (synchronized) with the image generated by the imaging system. The ability of the radar and optional Hall effect sensor 350 to accurately position the catheter tip 377 relative to the stereotaxic frame causes the pole piece to be moved by the actuators 109, 140 to optimize the position of the pole relative to the patient 390, and so on. Thus, the power required to operate the catheter tip can be reduced.

  FIGS. 8A and 8B show one embodiment of a catheter assembly 375 and guidewire assembly 379 for use with the CGCI device 1500. The catheter assembly 375 is an annular tool that includes a catheter body 376 that extends into a flexible portion 378 that is sufficiently flexible to allow a relatively stiff responsive tip 377 to be navigable within the patient. The tip 377 can be replaced with the tip 21 in FIG. 3, the tip 61 in FIG. 4, or the tip 81 in FIG.

  In one embodiment, the magnetic catheter assembly 375 in combination with the CGCI device 1500 reduces or eliminates the need for excessive shapes that are normally required to perform diagnostic and therapeutic procedures. During conventional catheter procedures, surgeons often face difficulties in guiding a conventional catheter to a desired location. This is because this process is manual and relies on manual dexterity to move the catheter, for example, in a tortuous path of the cardiovascular system. As such, surgeons are made available with an excess of catheters of various sizes and shapes to assist them during their work. This is because such work requires different bends in different situations due to natural anatomical differences between and between patients.

  By using the CGCI device 1500, only one catheter is required for most if not all patients. Catheter treatment is currently accomplished with the help of a CGCI system 1500 that guides the magnetic catheter 375 and guidewire assembly 379 to a desired location within the patient 390 body determined by manipulation of the surgeon's virtual tip 905. . The CGCI device 1500 overcomes most, if not all, of the physical limitations encountered by the surgeon while attempting to manually advance the catheter tip 377 within the patient's body. Guidewire assembly 379 (ie, magnetic tip 377 can be attracted or repelled by the electromagnet of CGCI device 1500) provides the flexibility needed to overcome the tortuous path.

  In one embodiment, the catheter tip 377 includes a guidewire assembly 379, a guidewire body 380, and a tip 381 that is responsive to a magnetic field. The tip 377 is guided along a sharp bend to advance the serpentine path. The responsive tips 377 and 381 of both the catheter assembly 375 and the guidewire assembly 379 each include a magnetic element such as a permanent magnet. The tips 377 and 381 include permanent magnets that are responsive to the external magnetic flux generated by the electromagnets 110, 115, 116 and the symmetrical portion 100 thereof.

  In one embodiment, the responsive tip 377 of the catheter assembly 375 is tubular and the responsive tip 381 of the guidewire assembly 379 is a solid cylinder. The responsive tip 377 of the catheter assembly 375 is a dipole having a longitudinal polarity orientation created by the two ends of the magnetic element disposed longitudinally therein. The responsive tip 381 of the guidewire assembly 379 is a dipole having a longitudinal polarity orientation created by the two ends of the magnetic element 377 disposed longitudinally therein. These longitudinal dipoles allow manipulation of both responsive tips 377 and 381 by the CGCI device 1500 as the electromagnet assembly 100, 101 and act on the tips 377 and 381, as desired by the operator "Drag" them together in position.

  9A and 9B show a further view of the CGCI structural support assembly 120. FIG. The structural support assembly 120 is configured to facilitate the use of x-rays and / or other surgical medical devices 502 in and around the patient during surgery. Two symmetrical left and right electromagnetic clusters 100 and 101 are mounted on a stainless steel guide rail 102 so that the two parts 100 and 101 are separated from each other as shown in FIGS. Can be moved. The rail 102 is fixed to the floor or the mounting pad with bolts. The clusters on the CGCI structure 120 roll within the rail 102 with relatively tight tolerances to prevent left / right or up / down movement during an earthquake. In one embodiment, the rails 102 are designed to withstand the forces of the Zone 4 earthquake when the CGCI structure cannot escape containment.

  The stainless steel flat toothed rail 104 is bolted to the floor or mounting pad under the CGCI structure 120. A Servo Dynamic model HJ96 C-44 brushless servomotor 128 (maximum torque: 27 pounds) with its associated servomotor amplifier model 815-BL 129 is provided for moving the clusters 101,100. The motor has a reduction gearbox with a ratio of 100: 1. A stainless steel spur gear attached to the reduction gear shaft meshes with the spur-equipped rail 104. Propulsion system 150 is configured to move CGCI portions 100 and 101 with a maximum force of 2700 pounds.

  9A and 9B further illustrate the CGCI assembly 120 when the system is set to “operating mode”. Two symmetrical clusters 100 and 101 are engaged as described above. 9A and 9B show the position of the spur-toothed rail 104 and the brushless servomotor 128. FIG.

  10 to 13 show a mode in which the main two left-right symmetric left and right coil clusters 100 and 101 are completely opened (non-operation mode), and the CGCI assembly 120 when the magnetic core is retracted. FIG. The rear view of the CGCI symmetric half shows a radial magnetic flux collection shield 105 having a C-arm upper cylinder coil support 106. In one embodiment, the CGCI assembly 120 is configured to accommodate structural considerations as well as safety considerations associated with the generation of a 2 Tesla magnetic field.

  FIG. 14 shows the high-level architecture of the CGCI system 1500 showing the main elements including the magnetic circuit controller 501. The controller 501 includes system memory, a torque / force matrix algorithm residing in 528 and a CPU / computer 527. A CPU / computer such as PC 527 provides calculation and control tasks. FIG. 14 shows a magnetic field sensor (such as a Hall sensor ring 350 mounted on a six coil electromagnetic circuit consisting of coils 51A, 51B, 51C, 51D, 51AT and 51DT, and an assembly forming X, Y and Z axis controls. MFS) 351, 352, 353, 354, 355 and 356 are further shown. D / A converter 550 and I / O block 551 provide communication between controller 501 and coil 51A and hydraulic system 140. A 6-channel DC amplifier 525 provides current to the coil.

  FIG. 14 shows the relationship between the joystick 900 and virtual tip 905 and the CPU 701 and the command structure. The CPU 701 displays on the display 730 controls that carry real-time images generated by X-rays, radar 1000, or other medical imaging techniques such as fluoroscopy, MRI, PET scan, CAT scan. A flow diagram of the command structure of the control scheme is shown by the use of a two-dimensional virtual planar coil polarity matrix. By assigning coil position and polarity elements to the direction of torque rotation and force field gradient on each two-dimensional plane consisting of six coil clusters 414, a computer program such as MathLab or Math Cad simplifies the combinatorial matrix, Appropriate combinations for the six coil current polarities and amplitudes can be calculated. In one embodiment, a boundary condition controller is used to adjust the magnetic field strength 405 and magnetic field gradient 406 in the effective region. The controller 501 calculates a magnetic field that is near the catheter tip 377 and is defined by a magnetic field on a two-dimensional plane in the effective area. The rules for calculating the magnetic field with a rotating coil on the surface of the sphere are described in US Patent Application Publication No. 2007/0016066.

  In one embodiment, a lookup table is used as a reference library used by controller 501. A look-up table consisting of settings for various scenarios of force and torque position and magnitude allows the controller 501 to use a learning algorithm for control calculations. The look-up table shortens the calculation process for optimal configuration and setting of coil current and pole position. The D / A and A / D system 550 allows connection of voltage and current measurement equipment and input from a magnetic field sensor (MFS) 350 array, ie, MFS 351, 352, 353, 354, 355 and 356. A magnetic field sensor that measures the interface magnetic field strength can cause CGCI to use a lower logic algorithm to calculate position, settings, coil current, and the like. The sub-simulation is performed before driving the power section of the CGCI device 1500, thus performing a “soft” level check before the operation performed by the actual machine. A two-level control architecture that starts with the sub-simulation architecture of the sub-simulation allows the surgeon or operator of the CGCI device 1500 to test each movement before it is actually performed. US Patent Application Publication No. 2007/0016066 describes a magnetic field regulator loop outlined in FIG. 14 that uses a Hall effect ring 350.

  Instead of using a radar system to locate the catheter tip 377, the present invention is optionally combined with a visualization and mapping tool such as EnSite NavX ™ technology available from St. Jude Medical. , Depending on the use of monitoring or measuring electrodes (58, 59 in FIG. 3, 80 in FIGS. 4 and 5). See, for example, US Pat. Nos. 6,990,370 and 6,939,309. Note that the entire disclosure is incorporated herein by reference.

  References for all directions (eg, up, down, up, down, left, right, left, right, up, down, up, down, vertical, horizontal, (Clockwise and counterclockwise) are used only for identification purposes to help the reader of the present invention understand and do not specifically limit the position, orientation or use of the present invention. References to coupling (eg, attached, linked, connected, etc.) are to be construed broadly and may include intermediate members between element connections and relative movement between elements. Thus, a reference to coupling does not necessarily mean that the two elements are connected directly and in a fixed relationship to each other. It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not limiting. Changes in detail or structure may be made without departing from the spirit of the invention as defined in the appended claims.

Claims (12)

A perfusion ablation electrode assembly for use with a perfusion catheter device comprising:
At least one fluid passage having an outlet disposed on an outer surface of the electrode assembly;
With permanent magnets,
A shield that separates the permanent magnet from the at least one passage and the exterior, and is substantially less oxidizable than the permanent magnet;
A distal electrode having an external electrode surface configured to deliver ablation energy ;
With
A distal member is disposed at a distal portion of the electrode assembly;
The electrode assembly further comprises a proximal member disposed proximal to the distal member;
The permanent magnet is disposed within the distal electrode ;
Proximal member of the electrode assembly, the saw including a proximal passage for at least one fluid having a proximal the outlet disposed on the outer surface of member, the proximal passage and said outlet, said permanent magnet A perfusion ablation electrode assembly, wherein the perfusion ablation electrode assembly is configured to direct fluid flow toward a target region proximate to an intersection between the proximal member and the distal ablation electrode . Wherein the distal electrode forms a least a portion of said shield, said distal electrode comprises a hardly oxidized conductive material than substantially the permanent magnet, the perfusion ablation electrode assembly according to claim 1. The conductive material included in the distal electrode is selected from the group consisting of platinum, gold, tantalum, iridium, stainless steel, palladium and mixtures thereof, and the conductive material is substantially more oxidized than the permanent magnet. 3. A perfusion ablation electrode assembly according to claim 1 or 2, which is plated on a substrate made of a biocompatible material that is difficult to resist.   4. The shield according to any one of claims 1 to 3, wherein the shield includes one or more materials selected from the group consisting of silicone, polyimide, platinum, gold, tantalum, iridium, stainless steel, palladium, and mixtures thereof. Perfusion ablation electrode assembly. The perfusion ablation electrode assembly according to any of claims 1 to 4 , wherein the permanent magnet comprises NdFeB. 6. The perfusion ablation electrode assembly according to any of claims 1-5 , further comprising at least one mapping electrode spaced proximally from the distal electrode capable of ablation. The perfusion ablation electrode assembly according to any of claims 1-6, wherein the proximal member comprises a non-conductive material and has a lower thermal conductivity than the material of the distal electrode. The perfusion ablation electrode assembly according to any of claims 1 to 7 , wherein the at least one proximal passage extends toward the distal electrode at an acute angle with respect to the longitudinal axis of the proximal member . Wherein comprises a proximal member non-conductive material, the said intersection with said outer surface and said outer electrode surface and said intersection of said distal electrode of the proximal member, the at least one proximal passageway the fluid flow The perfusion ablation electrode assembly according to any of claims 1 to 8 , wherein the perfusion ablation electrode assembly is configured to guide through an outlet towards a region adjacent to the intersection. It said electrode assembly further comprises at least one temperature sensor disposed on the permanent magnet, the perfusion ablation electrode assembly according to any one of claims 1-9. A shaft,
A perfusion ablation electrode assembly according to any of claims 1 to 10, coupled to the distal end of the shaft;
A catheter.   The catheter of claim 11, further comprising a second permanent magnet disposed near the distal end of the shaft and spaced from the permanent magnet in the perfusion ablation electrode assembly.

Images