Electrode catheter

Abstract

Provided is an electrode catheter with which it is easy to assess the degree of curvature of a catheter tip part when same is inserted into a body cavity, and with which it is easy to conform to the shape of the body cavity by controlling the pliability of the catheter tip part.　This electrode catheter has a longitudinal axis direction x and a circumferential direction, and has a distal end and a proximal end in the longitudinal axis direction x. The electrode catheter has: a tube (10) having a lumen extending in the longitudinal axis direction x; a cylindrical electrode (20) disposed on the outside of the distal part of the tube (10); and a conductor extending into the lumen of the tube (10) and connected to the electrode (20). The electrode (20) has a slit (23), and the extending direction of the slit (23) has a component in the circumferential direction.

Description

Electrode catheter

[0001] The present invention relates to an electrode catheter.

[0002] Catheters with electrodes are sometimes used in the examination and treatment of arrhythmias such as atrial fibrillation. During examinations, electrode catheters are inserted into the cardiac chambers to measure intracardiac potentials and identify the abnormal area of ​​the heart that is causing the arrhythmia. During treatment, electrode catheters are used in ablation procedures, in which high-frequency current is passed from the catheter's electrode to the myocardium causing the arrhythmia, cauterizing the source of the arrhythmia and electrically isolating it from the heart, and in defibrillation procedures, in which an electrical signal is sent from the catheter's electrode to the heart when atrial fibrillation occurs.

[0003] In ablation, since most of the abnormal electrical excitation that causes atrial fibrillation is said to originate from the pulmonary veins, pulmonary vein isolation is performed by electrically separating the left atrium and pulmonary veins by cauterizing the boundary between them. However, if the electrode of the electrode catheter does not line up with the entrance of the pulmonary veins, it will be difficult to perform the ablation efficiently. For this reason, electrode catheters with flexible tips have been devised.

[0004] For example, Patent Document 1 discloses an ablation catheter having a catheter body and a hollow, elongated tip electrode disposed at the distal end of the catheter body, the tip electrode having a flexible sidewall. Patent Document 2 discloses a basket catheter including a catheter shaft, a flexible basket catheter including a plurality of splines, and a plurality of electrodes attached to the plurality of splines, the plurality of electrodes forming a plurality of triangular groups along each of the plurality of splines. Patent Document 3 discloses an electrode catheter having a catheter shaft and a high-frequency current-carrying electrode that deforms into a basket shape.

[0005] Utility Model Registration No. 3161030 Special Publication No. 2020-536655 Japanese Patent Application Laid-Open No. 2018-75209

[0006] However, with the above-mentioned conventional electrode catheters, it was difficult to grasp the degree of curvature of the catheter tip, and there was also the problem that the electrode catheter had difficulty conforming to the shape of the body cavity when the electrode catheter was inserted into the treatment site from the entrance of the blood vessel or when the electrode catheter was rotated within the blood vessel or moved within the body cavity.

[0007] In view of the above circumstances, the present invention aims to provide an electrode catheter that makes it easy to grasp the degree of curvature of the catheter tip when the electrode catheter is inserted into a body cavity, and that easily conforms to the shape of the body cavity by controlling the ease of bending of the catheter tip.

[0008] The electrode catheter according to the embodiment of the present invention that can solve the above problems is as follows: [1] An electrode catheter having a longitudinal axis direction and a circumferential direction, and having a distal end and a proximal end in the longitudinal axis direction, comprising: a tube having a lumen extending in the longitudinal axis direction, a cylindrical electrode disposed outside the distal portion of the tube, and a lead wire extending into the lumen of the tube and connected to the electrode, the electrode having a slit, and the extending direction of the slit having a component in the circumferential direction.

[0009] In the electrode catheter described above, the cylindrical electrode disposed on the outside of the distal portion of the catheter tube has slits, and the extension direction of the slits has a circumferential component. Therefore, the degree of curvature of the distal portion of the catheter in which the electrodes are disposed can be determined by confirming the extent of the slit opening through observation such as X-ray observation. Furthermore, by controlling the number of electrodes disposed in the distal portion of the catheter and the number and shape of the slits in the electrodes, it is possible to form more flexible and less flexible portions in the distal portion of the catheter. This makes it possible to arbitrarily design the ease of bending of the distal portion of the catheter, making it easier to obtain an electrode catheter suitable for the treatment subject.

[0010] The electrode catheter according to the embodiment of the present invention is preferably any one of the following [2] to [9]. [2] The electrode catheter according to [1], wherein when a voltage is applied to the electrode, the distal end and the proximal end of the electrode in the longitudinal axis direction are at the same potential. [3] The electrode catheter according to [1] or [2], wherein the electrode has one or more first portions in which the slit is formed and two or more second portions in which the slit is not formed, in the longitudinal axis direction, and the second portions are arranged at the proximal end and the distal end of the electrode. [4] The electrode catheter according to [3], wherein two or more first portions and three or more second portions are arranged in the longitudinal axis direction. [5] The electrode catheter according to [4], wherein the first portions are formed symmetrically in a side view of the electrode. [6] The electrode catheter according to [4], wherein the length of one of the two or more first portions is different from the lengths of the other first portions of the two or more first portions in the longitudinal axis direction. [7] The electrode catheter according to any one of [1] to [6], wherein the slit is formed spirally in the circumferential direction. [8] The electrode catheter according to any one of [1] to [7], wherein the electrode has, in the longitudinal axis direction, one or more first portions in which the slits are formed and two or more second portions in which the slits are not formed, and the slits are formed so that the first portions have engaging portions. [9] The electrode catheter according to [8], wherein the electrode has two or more first portions and three or more second portions arranged in the longitudinal axis direction, and the engaging portions in the two or more first portions have different sizes.

[0011] According to the electrode catheter, the cylindrical electrode disposed on the outside of the distal portion of the catheter tube has slits, and the extension direction of the slits has a circumferential component, so that the degree of curvature of the distal portion of the catheter in which the electrodes are disposed can be determined by observing the extent to which the slits are open. Furthermore, by controlling the number of electrodes disposed in the distal portion of the catheter and the number and shape of the slits in the electrodes, it is possible to form more flexible and less flexible portions in the distal portion of the catheter. This makes it possible to arbitrarily design the ease of bending of the distal portion of the catheter, making it easier to obtain an electrode catheter suitable for the treatment subject.

[0012] FIG. 1 is a side view of an electrode catheter according to one embodiment of the present invention. FIG. 2 is a side view of an electrode catheter according to another embodiment of the present invention. FIG. 3 is a perspective view of a distal portion of an electrode catheter according to yet another embodiment of the present invention. FIG. 4 is a longitudinal cross-sectional view of the distal portion of the electrode catheter shown in FIG. 1. FIG. 5 is a perspective view of an electrode according to one embodiment of the present invention. FIG. 6 is a perspective view of the electrode shown in FIG. 6 when bent. FIG. 7 is a perspective view of an electrode according to yet another embodiment of the present invention. FIG. 8 is a perspective view of an electrode according to yet another embodiment of the present invention. FIG. 9 is a perspective view of an electrode according to yet another embodiment of the present invention. FIG. 10 is a side view of an electrode according to yet another embodiment of the present invention. FIG. 11 is a side view of an electrode according to yet another embodiment of the present invention. FIG. 12 is a side view of an electrode according to yet another embodiment of the present invention. FIG. 13 is a side view of an electrode according to yet another embodiment of the present invention. FIG. 14 is a side view of an electrode according to yet another embodiment of the present invention. FIG. 15 is a side view of an electrode according to yet another embodiment of the present invention.

[0013] The present invention will be described below based on the embodiments, but the present invention is not limited to the following embodiments and can be implemented with appropriate modifications within the scope of the above and below-described purposes, and all such modifications are included within the technical scope of the present invention. In addition, hatching and component symbols may be omitted in each drawing for convenience. In such cases, please refer to the specification or other drawings. Furthermore, the dimensions of various components in the drawings may differ from the actual dimensions, as priority is given to helping understand the features of the present invention.

[0014] An electrode catheter according to an embodiment of the present invention has a longitudinal axis direction and a circumferential direction, and has a distal end and a proximal end in the longitudinal axis direction, and comprises a tube having a lumen extending in the longitudinal axis direction, a cylindrical electrode positioned outside the distal portion of the tube, and a lead wire extending into the lumen of the tube and connected to the electrode, wherein the electrode has a slit, and the extension direction of the slit has a circumferential component.

[0015] When the distal portion of the tube, i.e., the distal portion of the electrode catheter, is bent, the electrode can bend in accordance with the bending of the tube, allowing the distal portion of the catheter to bend flexibly. In the electrode catheter according to an embodiment of the present invention, the cylindrical electrode disposed on the outside of the distal portion of the tube has slits, and the extension direction of the slits has a circumferential component, making it easy for the electrode to bend in accordance with the bending of the tube. This is because, when a cylindrical electrode is bent, the portion of the cylindrical wall of the electrode that is inside the bend contracts and the portion that is outside the bend expands. However, since the electrode has circumferentially extending slits, the electrode can easily contract and expand by opening and closing the slits. Therefore, by observing the extent to which the slits are open, the degree of bending of the electrode can be determined, and as a result, the degree of bending of the distal portion of the catheter can be grasped. The slits can be observed, for example, using X-ray imaging.

[0016] Furthermore, by controlling the number of electrodes arranged on the outside of the distal portion of the tube and the number and shape of the slits in the electrodes, it is possible to form more flexible and less flexible portions in the distal portion of the catheter. For example, even though slits are formed, the rigidity of the electrodes is higher than the rigidity of the tube. Therefore, when multiple electrodes are arranged in the distal portion of the tube, increasing the distance between the multiple electrodes in the extension direction of the tube makes it easier to bend, while decreasing the distance makes it less flexible. Furthermore, by arranging electrodes with slits that open more easily and electrodes with slits that open less easily in the distal portion of the tube, the portion where the former is arranged will be easier to bend, and the portion where the latter is arranged will be less flexible. By making such adjustments, it is possible to arbitrarily design the flexibility of the distal portion of the catheter.

[0017] As described above, by determining the degree of curvature of the distal portion of the catheter, it is possible to confirm whether the distal portion of the catheter is in sufficient contact with the target tissue, for example, the pulmonary vein ostium. Furthermore, by adjusting the flexibility of the distal portion of the catheter, it is possible to make the electrode catheter more easily conform to the shape of the body cavity when inserting the electrode catheter from the vascular ostium to the treatment site or when moving the electrode catheter within the body cavity, such as when rotating the electrode catheter within the blood vessel.

[0018] Electrode catheters according to embodiments of the present invention will now be described with reference to FIGS. 1 to 19. FIGS. 1 and 2 are side views of electrode catheters according to different embodiments of the present invention. FIG. 3 is a perspective view of the distal portion of an electrode catheter according to yet another embodiment of the present invention. FIG. 4 is a longitudinal cross-sectional view of the distal portion of the electrode catheter shown in FIG. 1. Slits in the electrode are omitted in FIGS. 1 to 4. FIGS. 5 and 6 are perspective views of an electrode according to one embodiment of the present invention. FIG. 7 is a perspective view of the electrode shown in FIG. 6 when bent. FIGS. 8 to 10 are perspective views of electrodes according to different embodiments of the present invention. FIGS. 11 and 12 are side views of electrodes according to different embodiments of the present invention. FIG. 13 is a perspective view of an electrode according to yet another embodiment of the present invention. FIG. 14 is a side view of the electrode shown in FIG. 13. FIGS. 15 to 19 are side views of electrodes according to different embodiments of the present invention.

[0019] As shown in Figure 1, the electrode catheter 100 has a longitudinal axis direction x and a circumferential direction z, and has a distal end and a proximal end in the longitudinal axis direction x. The longitudinal axis direction x of the electrode catheter 100 is the extension direction of the tube 10. As shown in Figures 2 and 3, if the distal portion of the tube 10 where the electrode 20 is located is curved, the longitudinal axis direction x is the direction that follows the curvature of the tube 10. The circumferential direction z of the electrode catheter 100 is the circumferential direction of the tube 10, i.e., the direction that follows the outer periphery of the tube 10.

[0020] The electrode catheter 100 also has a radial direction y, which is the radial direction of the tube 10. The radial direction y is a direction perpendicular to the longitudinal axis direction x and extends radially from the central axis of the tube 10.

[0021] The electrode 20 is a cylindrical member disposed on the outside of the tube 10, and therefore has a longitudinal axis direction x, a radial direction y, and a circumferential direction z, similar to the tube 10. However, the longitudinal axis direction x, radial direction y, and circumferential direction z of the tube 10 and the longitudinal axis direction x, radial direction y, and circumferential direction z of the electrode 20 do not need to be strictly the same and may be different.

[0022] In this specification, the direction toward the user's hand in the longitudinal axis direction x is referred to as the proximal side, and the opposite side to the proximal side, i.e., the direction toward the treatment target side, is referred to as the distal side.

[0023] When each member is divided into two equal parts in the extension direction, the part of each member located on the distal side is referred to as the distal portion, and the part of each member located on the proximal side is referred to as the proximal portion. The distal end of each member is the end located most distally in the extension direction of each member. The proximal end of each member is the end located most proximal in the extension direction of each member. The end of each member refers to the portion including the end of each member and its surrounding area. In other words, the distal end of each member refers to the portion including the distal end of each member and its surrounding area, and the proximal end of each member refers to the portion including the proximal end of each member and its surrounding area.

[0024] The distal portion of the electrode catheter 100 is preferably curved or bendable. By making the distal portion of the electrode catheter 100 curved or bendable, it becomes easier to follow the curvature of blood vessels and the inside of the heart, which can improve insertion ease and the effect of preventing damage to the body cavity wall.

[0025] The distal portion of the electrode catheter 100 may be naturally curved by being bent, or may be capable of being curved by a bending operation, or may not be capable of being curved.

[0026] As shown in Figures 1 and 2, a handle 50 may be connected to the proximal side of the tube 10. A user can easily operate the electrode catheter 100 by grasping the handle 50. A guidewire tube 51 through which a guidewire is inserted and a guidewire port 52 serving as an insertion port for the guidewire may be provided proximally from the handle 50. Also, it is preferable that a lead wire tube 40 is provided proximally from the handle 50, and a lead wire 30 (described later) connected to the electrode 20 is connected to a connector 41 through the lead wire tube 40. When the connector 41 is connected to an external device such as a power source or an electrocardiograph, the lead wire 30 can electrically connect the external device and the electrode 20.

[0027] The tube 10 may have a single lumen structure having one lumen, or a multi-lumen structure having multiple lumen. If the tube 10 has one lumen, there is no partition inside the tube 10 to separate the lumens, thereby increasing the flexibility of the tube 10 and improving the insertability of the electrode catheter 100. If the tube 10 has multiple lumens, components such as the lead wire 30 and bending operation wires to be placed in the lumens can be placed in separate lumens, preventing these components from contacting each other and damaging the components. Regardless of the number of lumens, it is preferable that the lumens of the tube 10 extend in the longitudinal axis direction x.

[0028] Examples of materials constituting the tube 10 include polyolefin resins such as polyethylene and polypropylene; polyamide resins such as nylon; polyester resins such as PET; polyimide resins; aromatic polyetherketone resins such as PEEK; polyetherpolyamide resins; polyurethane resins; fluorine-based resins such as PTFE, PFA, and ETFE; vinyl chloride resins; synthetic resins such as silicone resins; and rubbers such as natural rubber. These materials may be used alone or in combination. The material constituting the tube 10 is preferably a polyamide resin, and more preferably a polyamide elastomer. This provides the tube 10 with good slipperiness on its outer surface and appropriate rigidity, resulting in an electrode catheter 100 that is easily insertable into a body cavity.

[0029] The tube 10 may have a single-layer structure or a multi-layer structure. When the tube 10 has a multi-layer structure, for example, the tube 10 may have a resin tube that is interposed between layers of a metal braid made of stainless steel, carbon steel, a nickel-titanium alloy, or the like.

[0030] The length of the tube 10 in the longitudinal direction x can be selected to be an appropriate length for examination or treatment. For example, the length of the tube 10 in the longitudinal direction x can be 400 mm or more and 2000 mm or less. The length of the tube 10 in the longitudinal direction x should be relatively long when the tip of the electrode catheter 100 is inserted through a vein in the lower limb and delivered to the heart, but may be relatively short when the tip of the electrode catheter 100 is inserted through a subclavian vein or a jugular vein and delivered to the heart.

[0031] The outer diameter of the tube 10 is preferably 0.5 mm or more, more preferably 0.7 mm or more, and even more preferably 1.0 mm or more. By setting the lower limit of the outer diameter of the tube 10 within the above range, the tube 10 can be given appropriate rigidity and improved insertability into a body cavity. The outer diameter of the tube 10 is preferably 3.0 mm or less, more preferably 2.8 mm or less, and even more preferably 2.5 mm or less. By setting the upper limit of the outer diameter of the tube 10 within the above range, the outer diameter of the electrode catheter 100 can be prevented from becoming too large, thereby improving minimal invasiveness. The outer diameter of the tube 10 may also be 1.8 mm or less, 1.7 mm or less, 1.5 mm or less, 1.0 mm or less, or 0.8 mm or less. This allows the electrode catheter 100 to be used as a microcatheter with a small outer diameter at the distal end, making it possible to deliver the distal end of the electrode catheter 100 to the periphery of the coronary sinus.

[0032] The thickness of the tube 10, i.e., the thickness of the peripheral wall, is preferably 50 μm or more, more preferably 100 μm or more, and even more preferably 150 μm or more. By setting the lower limit of the thickness of the tube 10 within the above range, the rigidity of the tube 10 can be increased, making it possible to provide an electrode catheter 100 with good insertability into a body cavity. Furthermore, the thickness of the tube 10 is preferably 350 μm or less, more preferably 300 μm or less, and even more preferably 250 μm or less. By setting the upper limit of the thickness of the tube 10 within the above range, the lumen of the tube 10 can be widened, allowing the electrodes of the electrode catheter 100 to be multipolar.

[0033] As shown in Figures 1 to 3, a cylindrical electrode 20 is disposed on the outside of the distal portion of the tube 10. Although a single electrode 20 may be disposed, it is preferable that a plurality of electrodes 20 are disposed at intervals in the longitudinal axis direction x. The electrode 20 can be used to measure cardiac potential to diagnose arrhythmia, or to apply a high-frequency current to the electrode 20 to cauterize body tissue in order to treat arrhythmia. In this case, the electrode 20 can function as a measurement electrode or reference electrode during potential measurement, as an electrode through which a high-frequency current is applied, or as an electrode for applying an electrical signal.

[0034] 4, the electrodes 20 are preferably disposed outside side holes 11 formed so as to penetrate the side wall of the distal portion of the tube 10. At least one side hole 11 is preferably formed for each electrode 20.

[0035] The electrode 20 can be connected to a conductor 30 by passing the conductor 30 through a side hole 11 in the side wall of the tube 10. The shape of the side hole 11 when viewed from the side of the tube 10 is not particularly limited as long as the conductor 30 can pass through it, but it can be, for example, circular or rectangular. The method for forming the side hole 11 is not particularly limited, but examples include a method of piercing the side wall of the tube 10 with a rod-shaped member having a sharp tip, such as an awl, or a method of irradiating it with laser light.

[0036] In the portion of the outer surface of the tube 10 where the electrode 20 is to be disposed, a recess 12 is preferably formed inside the electrode 20 in the radial direction y. This allows the electrode 20 to be disposed in the recess 12, preventing the electrode 20 from protruding outward in the radial direction y and preventing the electrode 20 from getting caught on a body cavity wall such as the inner wall of a blood vessel or the heart, which could reduce insertion ability or damage the body cavity wall. The method for forming the recess 12 on the outer surface of the side wall of the tube 10 is not particularly limited, but examples include cutting with a drill or other device, applying pressure with a rod-shaped object, thermal processing in which a heated rod-shaped object is pressed against the electrode 20, and irradiating with laser light.

[0037] As described above, the electrode 20 is connected to the conductor 30 passed through the side hole 11 provided in the tube 10, but is disposed on the outer surface of the tube 10 in areas other than the side hole 11. The inner surface of the cylindrical electrode 20 is preferably in contact with the outer surface of the tube 10. In other words, the tube 10 is preferably present inside the inner surface of the cylindrical electrode 20 in areas other than the side hole 11, and the electrode 20 is preferably disposed on top of the tube 10 from the inside to the outside in the radial direction y. That is, the tube 10 and the electrode 20 are preferably disposed in this order from the inside to the outside in the radial direction y. This allows the electrode 20 to bend in accordance with the curvature of the tube 10. Therefore, as will be described in detail later, the degree of curvature of the tube 10 can be determined by detecting the degree of curvature of the electrode 20 by observing the degree of opening of the slit 23, i.e., the length of the opening 23g of the slit 23 in the longitudinal axis direction x.

[0038] An inner tube 70 may be disposed in the lumen of the tube 10. This allows the lead wire 30 to be disposed inside the tube 10 but outside the inner tube 70, so that when a treatment tool such as a guide wire or other catheter is inserted into the lumen of the inner tube 70, the lead wire 30 and these components will not interfere with each other, thereby achieving the effects of stabilizing the connection between the lead wire 30 and the electrode 20 and preventing damage to the lead wire 30.

[0039] The material constituting the electrode 20 may be any material as long as it is conductive, and examples thereof include metals and mixtures containing metals and resins. Among these, metals such as platinum, platinum-iridium alloys, stainless steel, and tungsten, or conductive resins are preferably used as the material for the electrode 20. When the electrode 20 is made of conductive resin, it is preferable to mix a contrast agent such as barium sulfate or bismuth oxide into the electrode 20 so that it can be seen under X-ray fluoroscopy.

[0040] The number of electrodes 20 is not particularly limited, and may be, for example, 1 or more, 2 or more, 3 or more, 5 or more, 8 or more, 10 or more, 15 or more, or 50 or less, 40 or less, 30 or less, 25 or less, 20 or less, etc. Depending on the purpose of using the electrode catheter 100, multiple electrodes 20 may form an electrode group, and the multiple electrode groups may be arranged at intervals in the longitudinal axis direction x.

[0041] The material constituting the conductor 30 need only be electrically conductive, and examples thereof include metal wires such as copper wire, iron wire, stainless steel wire, piano wire, tungsten wire, nickel-titanium alloy wire, etc. Among these, stainless steel wire is particularly preferred because it has straightness and rigidity, making it easy to pass the conductor 30 through the side hole 11 of the tube 10 and also because breakage of the connection between the conductor 30 and the electrode 20 is unlikely to occur.

[0042] Each conductor 30 may be a solid wire or a stranded wire. The cross-sectional shape of each conductor 30 perpendicular to the longitudinal axis direction x may be, for example, a circle, a polygon, or a combination of these. The major axis of each conductor 30 is not particularly limited and is, for example, preferably 0.05 mm or more, more preferably 0.08 mm or more, even more preferably 0.1 mm or more, and preferably 0.3 mm or less, more preferably 0.2 mm or less, and even more preferably 0.15 mm or less. The major axis of each conductor 30 refers to the diameter of a circumscribed circle of each conductor 30 in a cross-section perpendicular to the longitudinal axis direction x, regardless of whether the conductor 30 is a solid wire or a stranded wire and regardless of the cross-sectional shape.

[0043] The conducting wire 30 and the electrode 20 can be connected by a method such as laser welding, resistance welding, adhesion with an adhesive, etc. The conducting wire 30 may be directly connected to the electrode 20, or may be indirectly connected to the electrode 20 via another conductive member (not shown) that has conductivity between the conducting wire 30 and the electrode 20.

[0044] The electrode catheter 100 may have a distal tip 60. Examples of the distal tip 60 include a hollow tube member, a hemispherical member, a cover-shaped member, or the like connected to the distal end of the tube 10. The hemispherical member or cover-shaped member may have a through-hole formed therein through which a guidewire can be inserted. By having the distal tip 60, the electrode catheter 100 can prevent unexpected foreign matter such as blood from entering the lumen of the tube 10 in which the lead wire 30 is disposed during use of the electrode catheter 100. Furthermore, if the distal tip 60 is made of a highly flexible material, it is possible to prevent the distal end of the electrode catheter 100 from damaging the wall of a body cavity such as the heart or blood vessels, and to improve the insertability of the electrode catheter 100 within a body cavity.

[0045] The material constituting the distal tip 60 can refer to, for example, the material constituting the tube 10. Alternatively, the distal tip 60 can be made of the material constituting the electrode 20, so that the distal tip 60 functions as a distal electrode.

[0046] 5 and 6 , the electrode 20 has slits 23, and the extending direction of the slits 23 has a component in the circumferential direction z. The slits 23 are preferably provided by cutting notches into the sidewall of the cylindrical electrode 20. The notches can be formed using a micromachining machine such as a laser cutter, for example.

[0047] The slits 23 are provided so as not to divide the electrode 20 in the longitudinal axis direction x. That is, the slits 23 provided continuously on the side wall of the electrode 20 preferably have a start point 23 a and an end point 23 b. The start point 23 a and the end point 23 b of the slit 23 can also be said to be one end and the other end in the extension direction of the slit 23.

[0048] That the slit 23 has a component in the circumferential direction z means that the slit 23 is arranged at a different position in the circumferential direction z from the start point 23a up to the end point 23b of the slit 23. The extension direction of the slit 23 may have a circumferential direction z component of 100%, or may have a circumferential direction z component and a longitudinal axis direction x component. That the slit 23 has a longitudinal axis direction x component means that the slit 23 is arranged at a different position in the longitudinal axis direction x from the start point 23a up to the end point 23b of the slit 23.

[0049] The electrode 20 may have one or more slits 23. When multiple slits 23 are provided, the shapes, extension directions, and lengths of the multiple slits 23 may be the same or different from one another. One slit 23 is a continuous slit extending from a start point 23a to an end point 23b. For example, in the examples shown in FIGS. 5 and 6, four slits 23 are provided.

[0050] The length of the slit 23 in the extension direction may be shorter than, the same as, or longer than the length of the electrode 20 in the circumferential direction z.

[0051] The cuts in the slits 23 are formed by a processing machine such as a micromachining machine, and the width of the opening in the slit 23 perpendicular to the extension direction of the cuts is preferably very short compared to the length of the electrode 20 in the longitudinal axis direction x. However, from a microscopic perspective, as will be described in detail later, the slits 23 have openings 23g as shown in FIG. 7 , and the openings 23g preferably have a width perpendicular to the extension direction of the cuts. The width of the openings 23g can vary depending on the degree of curvature of the electrode 20. For example, the length of the electrode 20 in the longitudinal axis direction x is preferably 1 to 5 mm, while the width of the openings 23g is preferably 10 to 100 μm. This allows the electrode 20 to efficiently apply voltage and measure potential while providing the slits 23 in the electrode 20.

[0052] Furthermore, the width of the opening 23g of the cut in the slit 23 is preferably shorter than the thickness of the electrode 20 in the radial direction y when the electrode 20 is in its natural state. The thickness of the electrode 20 in the radial direction y can be set to, for example, 0.5 to 3.0 mm. This allows the electrode 20 to be easily bent without impairing its rigidity.

[0053] 5, it is preferable that the plurality of slits 23 are provided at different positions in the circumferential direction z. This makes it easier for the electrode 20 to follow the curvature of the tube 10 regardless of the direction in which the tube 10 is curved in the circumferential direction z.

[0054] As shown in Fig. 6, the plurality of slits 23 may be provided on one side in the circumferential direction z. This allows the slits 23 to be provided in a portion that is on the outer side of the curve of the tube 10, and therefore, if such an electrode 20 is disposed in an electrode catheter 100 in which the curve direction of the distal portion of the tube 10 is fixed, such as the electrode catheter 100 having a loop-shaped distal portion shown in Fig. 3, it becomes easy to curve the electrode 20 to follow the curve of the tube 10.

[0055] As shown in Figure 7, when the tube 10 is bent, the electrode 20 can bend to follow the curvature of the tube 10. At this time, it is preferable that the portion of the slit 23 provided in the electrode 20 located outside the curvature open, increasing the length of the opening 23g in the longitudinal axis direction x, thereby bending the electrode 20. Since the degree of opening of the slit 23, i.e., the length of the opening 23g in the longitudinal axis direction x, is shorter the smaller the degree of curvature and longer the larger the degree of curvature, the degree of curvature of the electrode 20 can be determined by observing the degree of opening of the slit 23, i.e., the length of the opening 23g in the longitudinal axis direction x. As a result, the degree of curvature of the tube 10, i.e., the degree of curvature of the distal portion of the electrode catheter 100, can be determined, which enables the distal portion of the electrode catheter 100 to be brought into sufficient contact with the target tissue, thereby improving the accuracy of treatment and examination.

[0056] The degree of opening of the slit 23, that is, the length of the opening 23g in the longitudinal axis direction x, can be confirmed by observation such as X-ray observation.

[0057] 5 and 6 , the length from the proximal end 20p of the electrode 20 to the slit 23 provided at a position closest to the proximal end 20p in the longitudinal axis direction x is preferably longer than the thickness in the radial direction y of the electrode 20. Furthermore, the length from the distal end 20d of the electrode 20 to the slit 23 provided at a position closest to the distal end 20d in the longitudinal axis direction x is preferably longer than the thickness in the radial direction y of the electrode 20. This makes it easier to determine the degree of bending of the electrode 20 by comparing the degree of opening of the slit 23 at the end of the electrode 20 and the portion where the slit 23 is provided.

[0058] In the longitudinal axis direction x in a side view of the electrode 20, the length from the proximal end 20p of the electrode 20 to the slit 23 provided at a position closest to the proximal end 20p is preferably longer than the length to the adjacent slit 23, and the length from the distal end 20d of the electrode 20 to the slit 23 provided at a position closest to the distal end 20d is preferably longer than the length to the adjacent slit 23. This increases the rigidity of the end of the electrode 20, thereby preventing the opening 23g from opening more than necessary. As a result, by observing the length of the opening 23g in the longitudinal axis direction x, it is possible to more accurately determine the degree of curvature of the tube 10.

[0059] The electrode 20 preferably has the slits 23 formed in a cylindrical member, or may have the slits formed in a ring-shaped member made of a plate-like material. The electrode 20 is preferably not a coil formed by winding a wire material.

[0060] In the case of a coil formed by winding a wire, irregularities corresponding to the diameter of the wire are formed on the outer surface of the electrode 20, but it is preferable that the slits 20 do not form irregularities on the outer surface of the electrode 20 that are equal to or greater than half the thickness of the electrode 20. It is more preferable that the slits 20 do not form irregularities on the outer surface of the electrode 20 that are equal to or greater than one-third the thickness of the electrode 20, and it is even more preferable that the slits 20 do not form irregularities on the outer surface of the electrode 20 that are equal to or greater than one-quarter the thickness of the electrode 20. By not forming irregularities on the outer surface of the electrode 20 that are greater than a predetermined value, the outer surface of the electrode 20 can more easily come into contact with the body cavity wall, facilitating effective treatment and examination.

[0061] When multiple electrodes 20 are arranged on the tube 10, the bendability of the tube 10 can be controlled by arranging more bendable electrodes 20 in portions of the tube 10 that are desired to be more bendable in the longitudinal axis direction x and less bendable electrodes 20 in portions that are not desired to be bent. As a result, it is possible to arbitrarily design the bendability of the distal portion of the electrode catheter 100. A more bendable electrode 20 can be obtained by increasing the number of slits 23 or by increasing the circumferential direction z component of the extension direction of the slits 23. A less bendable electrode 20 can be obtained by not providing slits 23, by reducing the number of slits 23, or by reducing the circumferential direction z component of the extension direction of the slits 23. In this way, when multiple electrodes 20 are arranged on the tube 10, the electrode catheter 100 may include electrodes 20 that do not have slits 23. In other words, it is sufficient that at least one cylindrical electrode 20 arranged on the outside of the distal portion of the tube 10 has a slit 23.

[0062] Alternatively, since the rigidity of the electrodes 20 is likely to be higher than the rigidity of the tube 10 even if slits 23 are provided, the ease of bending of the tube 10 can be adjusted by increasing the spacing between the multiple electrodes 20 in the longitudinal axis direction x of the tube 10 in the part that is desired to be more curved, and by decreasing the spacing between the multiple electrodes 20 in the longitudinal axis direction x of the tube 10 in the part that is not desired to be more curved.

[0063] When a voltage is applied to the electrode 20, the distal end 20d and the proximal end 20p of the electrode 20 in the longitudinal axis direction x are preferably at an equipotential. This makes it easier to apply a desired voltage to the target tissue by the electrode 20, allowing the electrode catheter 100 to efficiently perform cauterization or defibrillation. This configuration can be achieved by providing the slits 23 so that the electrode 20 is not divided in the longitudinal axis direction x. Since the slits 23 do not divide the electrode 20 in the longitudinal axis direction x, the electrode 20 can exist continuously from the proximal end 20p to the distal end 20d. This allows the electrode 20 to be at an equipotential throughout from the proximal end 20p to the distal end 20d in the longitudinal axis direction x, even if the slits 23 are provided.

[0064] As shown in Fig. 8, the slits 23 are preferably formed in a spiral shape in the circumferential direction z. The spiral shape allows the slits 23 to be arranged throughout the entire circumferential direction z. Furthermore, when the slits 23 are formed in a spiral shape, the multiple slits 23 extending in the circumferential direction z can be arranged side by side in the longitudinal axis direction x in a side view of the electrode 20. This makes it easier for the electrode 20 to bend in accordance with the curvature of the tube 10, regardless of the direction in the circumferential direction z in which the tube 10 is bent.

[0065] However, the electrode 20 having the slit 23 spirally formed in the circumferential direction z differs from a coil formed by winding a wire. For example, in a compressible coil, a gap is formed between each turn of the wire. Furthermore, in the case of a tightly wound, i.e., non-compressible, coil, a gap is formed between each turn of the wire when a tensile force is applied to the coil. However, in either case, the length from one end of the coil to the gap closest to that end and the length from the other end of the coil to the gap closest to that end in the longitudinal axis direction depend on the thickness of the wire forming the coil. In contrast, the electrode 20 having the slit 23 spirally formed in the circumferential direction z does not have a structure formed by winding a wire, and the slit 23 can be located at any position regardless of the thickness or outer diameter of the electrode 20.

[0066] In this case, the separation distance in the longitudinal direction x between the plurality of slits 23 extending in the circumferential direction z that are arranged so as to be aligned in the longitudinal direction x in a side view of the electrode 20 may be the same as shown in Fig. 8 or may be different as shown in Fig. 9. The separation distance can be said to be the pitch of the spirally formed slits 23, and the pitch of the spirally formed slits 23 may be the same or different in the longitudinal direction x.

[0067] 10, the spirally formed slit 23 may be interrupted midway, and the spiral shape may be formed by a plurality of slits 23 each having a starting point 23a and an ending point 23b. In this case, as shown in FIG. 10, one slit 23 may be disposed on an extension of another slit 23, and the ending point 23b of one slit may face the starting point 23a of another slit 23. Alternatively, although not shown, the ending point 23b of one slit 23 may be offset from the starting point 23a of another slit 23.

[0068] 11 and 12 , in the longitudinal axis direction x, the electrode 20 has one or more first portions 21 in which slits 23 are formed and two or more second portions 22 in which no slits 23 are formed, and it is preferable that the slits 23 are formed so that the first portions 21 have engaging portions 23 e. This prevents the electrode 20 from stretching too much in the longitudinal axis direction x, making it easier to control the degree of curvature of the electrode 20.

[0069] As shown by dashed lines in Figures 11, 12, and 15 to 19, in a side view of the electrode 20, i.e., when the electrode 20 is viewed from a direction perpendicular to the longitudinal axis direction x, the first portion 21 is a portion in which the slits 23 exist in a band-shaped region in the circumferential direction z, and the second portion 22 is a portion in which the slits 23 do not exist in a band-shaped region in the circumferential direction z. In the side view of the electrode 20, one slit 23 may be formed in one first portion 21 as shown in Figures 11, 12, and 17, or multiple slits 23 may be formed in one first portion 21 as shown in Figures 15, 16, 18, and 19. The first portion 21 and the second portion 22 are preferably arranged side by side in the longitudinal axis direction x.

[0070] 13 and 14 , in a configuration in which the slits 23 are formed in a spiral shape, the plurality of slits 23 are formed at intervals in the longitudinal axis direction x in a side view of the electrode 20 as shown in Fig. 14 , and a band-like region in the circumferential direction z in which no slits 23 exist between adjacent slits 23 may be formed as shown by the dashed-dotted line in Fig. 14 . Even in such a case, if the length in the longitudinal axis direction x of the band-like region in the circumferential direction z in which no slits 23 exist between adjacent slits 23 is shorter than the maximum length L of the slits 23 in the longitudinal axis direction, the region is also considered to be included in the first region 21.

[0071] 11 , for example, the engaging portions 23e may be provided so that trapezoids engage with each other. In this case, it is preferable that the cuts forming the slits 23 have a circumferential extending portion 23z whose main extending direction is the circumferential direction z and a longitudinal extending portion 23x whose main extending direction is the longitudinal direction x, and that the angle θ enclosed by the circumferential extending portion z and the longitudinal extending portion x is an acute angle.

[0072] Alternatively, the engaging portions 23e may be provided so that circular shapes engage with each other, as shown in Fig. 12. Alternatively, the engaging portions 23e may be provided so that arbitrary shapes engage with each other.

[0073] Regardless of the shape of the engaging portions 23e, it is preferable that the engaging portions 23e restrict the second portions 22 at both ends of the first portion 21 in which the slits 23 having the engaging portions 23e are formed from moving away from each other in the longitudinal axis direction x. Depending on how the engaging portions 23e are formed, it is also possible to configure the second portions 22 at both ends of the first portion 21 to be allowed to move away from each other to a certain extent, and the ease of bending of the electrode 20 can be controlled by the degree of this allowance. Such a configuration can be achieved by increasing the gap of the slits 23 in which the engaging portions 23e are provided to a certain extent.

[0074] If the electrode 20 has a slit 23 having an engaging portion 23e, when the tube 10 is bent, the engaging portion 23e may restrict movement in the longitudinal axis direction x while allowing movement in the radial direction y. This allows the engaging portion 23e to shift in the radial direction y, thereby allowing the electrode 20 to bend in accordance with the bending of the tube 10.

[0075] The engaging portions 23e are preferably formed so as to be aligned in the circumferential direction z. This makes it easier to control the movement of the second portions 22 at both ends of the first portion 21 in directions away from each other.

[0076] 13 to 15 , in the longitudinal axis direction x, the electrode 20 has one or more first portions 21 each having a slit 23 formed therein and two or more second portions 22 each having no slit 23 formed therein, and the second portions 22 are preferably disposed at the proximal and distal ends of the electrode 20. It is easy to connect a conductor 30 to the second portions 22 each having no slit 23 formed therein, and disposing the second portions 22 at both ends of the electrode 20 makes it easy to connect the conductor 30 to the ends of the electrode 20. This facilitates connection of the conductor 30 to the electrode 20, while also making it easier to observe the degree of curvature of the electrode 20 by observing the degree of opening of the slit 23 in the first portion 21 disposed at the center of the electrode 20.

[0077] 13 to 15, in the first portion 21, the slits 23 are preferably formed so as to align in the longitudinal axis direction x in a side view of the electrode 20. This makes it easier for the first portion 21 to bend.

[0078] 15 , the first portion 21 may be formed so that the engaging portions 23 e are aligned in the longitudinal axis direction x in a side view of the electrode 20. This makes it easier to control the movement of the second portions 22 at both ends of the first portion 21 in directions away from each other.

[0079] 16 , it is preferable that two or more first portions 21 and three or more second portions 22 are arranged in the electrode 20 in the longitudinal axis direction x. This allows a configuration in which a second portion 22 without a slit 23 is located between two first portions 21 with slits 23 formed therein, making it easier to control the degree of curvature of the electrode 20 in the longitudinal axis direction x.

[0080] 17 , when two or more first portions 21 and three or more second portions 22 are arranged in the electrode 20 in the longitudinal axis direction x, it is preferable that the first portions 21 are formed symmetrically in a side view of the electrode 20, that is, when the electrode 20 is viewed from a direction perpendicular to the longitudinal axis direction x. This allows the degree of curvature of the electrode 20 to be symmetrical.

[0081] 18 , when two or more first portions 21 and three or more second portions 22 are arranged in the electrode 20 in the longitudinal axis direction x, it is preferable that the length of one of the two or more first portions 21 is different from the lengths of the other first portions 21. By changing the length in the longitudinal axis direction x of the first portion 21 in which the slit 23 is provided, it is possible to change the degree of curvature of the electrode 20 along the longitudinal axis direction x.

[0082] The length of the first portion 21 in the longitudinal axis direction x can be adjusted, for example, by changing the number of cuts forming the slits 23 arranged in the longitudinal axis direction x. In this case, the number of cuts can be counted as one continuous cut that is continuous in the circumferential direction z in a side view of the electrode 20. Alternatively, the length of the first portion 21 in the longitudinal axis direction x can also be adjusted by the length of one slit 23 extending in the longitudinal axis direction x.

[0083] 19 , two or more first portions 21 each having a slit 23 formed therein and three or more second portions 22 each having no slit 23 formed therein are arranged in the longitudinal axis direction x in the electrode 20, and the slits 23 are formed so that the first portions 21 have engaging portions 23e, and it is preferable that the engaging portions 23e have different sizes in the two or more first portions 21. Depending on the size of the engaging portions 23e, it is possible to change the degree to which the second portions 22 at both ends of the first portion 21 are restricted from moving in directions away from each other, and therefore, by making the engaging portions 23e of the two or more first portions 21 different in size, it becomes easier to control the ease with which the electrode 20 bends along the longitudinal axis direction x.

[0084] This application claims the benefit of priority based on Japanese Patent Application No. 2024-023979, filed on February 20, 2024. The entire contents of the specification of Japanese Patent Application No. 2024-023979, filed on February 20, 2024, are incorporated herein by reference.

[0085] 10: Tube 11: Side hole 12: Recess 20: Electrode 20d: Distal end of electrode 20p: Proximal end of electrode 21: First portion 22: Second portion 23: Slit 23a: Starting point 23b: Ending point 23e: Engagement portion 23g: Opening 23x: Longitudinal extension portion 23z: Circumferential extension portion 30: Conductor 40: Conductor tube 41: Connector 50: Handle 51: Guidewire tube 52: Guidewire port 60: Distal tip 70: Inner tube 100: Electrode catheter

Claims

1. An electrode catheter having a longitudinal axis direction and a circumferential direction, and having a distal end and a proximal end in the longitudinal axis direction, comprising: a tube having a lumen extending in the longitudinal axis direction; a cylindrical electrode disposed on the outside of the distal portion of the tube; and a conducting wire extending into the lumen of the tube and connected to the electrode, wherein the electrode has a slit, and the direction of extension of the slit has a component in the circumferential direction.

2. The electrode catheter according to claim 1, wherein when a voltage is applied to the electrode, the distal end and the proximal end of the electrode in the longitudinal direction are at the same potential.

3. An electrode catheter according to claim 1 or 2, wherein the electrode has, in the longitudinal axis direction, one or more first portions in which the slits are formed and two or more second portions in which the slits are not formed, and the second portions are disposed at the proximal end and distal end of the electrode.

4. The electrode catheter according to claim 3, wherein the electrode has two or more first portions and three or more second portions arranged in the longitudinal direction.

5. The electrode catheter according to claim 4, wherein the first portion is formed symmetrically in a side view of the electrode.

6. An electrode catheter according to claim 4, wherein the length of one of said two or more first sections in the longitudinal axis direction is different from the length of the other of said two or more first sections.

7. An electrode catheter according to claim 1 or 2, wherein the slit is formed spirally in the circumferential direction.

8. An electrode catheter as described in claim 1 or 2, wherein the electrode has, in the longitudinal axis direction, one or more first portions in which the slits are formed and two or more second portions in which the slits are not formed, and the slits are formed so that the first portions have engaging portions.

9. An electrode catheter as described in claim 8, wherein two or more first portions and three or more second portions are arranged on the electrode in the longitudinal axis direction, and the engaging portions of the two or more first portions are different in size.

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