Electrode catheter

Abstract

To provide a technology capable of improving freedom of a shape of an electrode assembly adjusted by advancing / retracting of an inner shaft.SOLUTION: An electrode catheter includes: an outer shaft 22 in which a lumen 20 is formed; an inner shaft 24 retractably inserted in the lumen 20; an electrode assembly 28 at least a part of which is provided on a distal side relative to a distal side end of the outer shaft 22. The electrode assembly 28 is provided with a plurality of splines 32 one end part of which is connected to the outer shaft 22 and the other end part of which is connected to the inner shaft 24. The inner shaft 24 can advance / retract between a projection position P1 projecting from a distal end opening 30 provided at the distal end of the lumen 20 and a housing position P2 housed on the depth side from the distal end opening 30.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to electrode catheters. [Background technology]

[0002] Patent Document 1 discloses an electrode catheter including an outer shaft with a lumen, an inner shaft inserted into the lumen so as to be able to advance and retreat, and an electrode assembly provided distal to the distal end of the outer shaft. The electrode assembly includes a plurality of splines connected to the outer shaft and the inner shaft. The shape of the electrode assembly can be adjusted by the deformation of the splines following the advance and retreat of the inner shaft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-057093 Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors of the present invention have discovered a new idea for increasing the degree of freedom in the shape of the electrode assembly that is adjusted by moving the inner shaft back and forth.

[0005] An object of the present disclosure is to provide a technique that can increase the degree of freedom in the shape of the electrode assembly that is adjusted by advancing and retracting the inner shaft. [Means for solving the problem]

[0006] The electrode catheter of the first item of the present disclosure comprises an outer shaft having a lumen formed therein, an inner shaft inserted into the lumen so as to be able to advance and retreat, and an electrode assembly having at least a portion thereof disposed distal to the distal end of the outer shaft, the electrode assembly having a plurality of splines having one end connected to the outer shaft and the other end connected to the inner shaft, and the inner shaft being able to advance and retreat between a protruding position where it protrudes from a distal end opening provided at the distal end of the lumen and a retracted position where it is retracted to the rear side of the distal end opening.

[0007] The electrode catheter of the second item of the present disclosure comprises an outer shaft having a lumen formed therein, an inner shaft inserted into the lumen so as to be able to advance and retreat, and an electrode assembly having at least a portion disposed distal to the distal end of the outer shaft, wherein the electrode assembly comprises a plurality of splines having one end connected to the outer shaft and the other end connected to the inner shaft, each of the plurality of splines having a distal folded end that folds back at the distal end of the spline in the advance and retreat direction of the inner shaft when the inner shaft is positioned anywhere within its advance and retreat range, and each of the plurality of splines is flexibly deformable so as to change the advance and retreat distance from the inner shaft to the distal folded end in accordance with the advance and retreat of the inner shaft. [Effects of the Invention]

[0008] According to the present disclosure, the degree of freedom in the shape of the electrode assembly that is adjusted by moving the inner shaft forward and backward can be increased. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is an explanatory diagram showing the state of use of the electrode catheter of the first embodiment. [Figure 2] FIG. 1 is a side view schematically showing an electrode catheter of a first embodiment. [Figure 3]1 is a schematic diagram showing an electrode assembly according to a first embodiment together with a peripheral structure. [Figure 4] 1 is a schematic diagram of the electrode assembly of the first embodiment viewed from the advance / retract direction together with the surrounding structure. FIG. [Figure 5] 4 is a cross-sectional view taken along the line AA in FIG. 3. [Figure 6] FIG. 3 is a first explanatory view schematically showing the operation of the electrode assembly of the first embodiment. [Figure 7] FIG. 4 is a second explanatory view schematically illustrating the operation of the electrode assembly of the first embodiment. [Figure 8] FIG. 10 is a third explanatory view schematically showing the operation of the electrode assembly of the first embodiment. [Figure 9A] FIG. 1 is a diagram schematically illustrating an electrode assembly according to a reference embodiment. [Figure 9B] 10A to 10C are explanatory diagrams relating to the operation of the electrode assembly of the reference embodiment. [Figure 10] 10A and 10B are explanatory diagrams illustrating a state in which an electrode assembly according to a reference embodiment is used. [Figure 11] FIG. 2 is an explanatory diagram of an irrigation port according to the first embodiment. [Figure 12] FIG. 10 is a schematic view of the electrode assembly of the second embodiment, viewed from the forward / backward direction together with the surrounding structure. [Figure 13] FIG. 10 is a schematic diagram showing an electrode assembly according to a second embodiment, viewed obliquely together with its surrounding structure. [Figure 14] 10A to 10C are explanatory views relating to the operation of the electrode assembly of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments for carrying out the present disclosure will be described. Identical or equivalent components are designated by the same reference numerals, and redundant explanations will be omitted. In each drawing, components are omitted, enlarged, or reduced as appropriate for the sake of convenience. The drawings should be viewed in accordance with the orientation of the reference numerals.

[0011] (First embodiment) Refer to FIG. 1. The following description begins with a usage scenario of the electrode catheter 10. The electrode catheter 10 is inserted into the body of a living organism for treatment. Here, "treatment" refers to an action related to medical treatment or examination of the living organism. Here, treatment refers to, for example, ablation (Pulsed Field Ablation (PFA), radiofrequency ablation, etc.) and defibrillation. Here, examination refers to, for example, electrocardiography. Here, an example is described in which the treatment target 16 is the terminal end of a pulmonary vein 14 opening into the left atrium 12 of the living organism. In other words, the treatment target 16 of the living organism is the terminal end of a second organ (here, the pulmonary vein) opening into a first organ (here, the heart) of the living organism. This treatment target 16 is provided with a tapered portion 16a that tapers toward the back when viewed from the first organ. This treatment target 16 is merely an example, and various parts of the living organism may be the treatment target 16, regardless of whether or not it has a tapered portion 16a.

[0012] See Figures 2, 3, and 4. The electrode catheter 10 includes a cylindrical outer shaft 22 having a lumen 20 and an inner shaft 24 inserted into the lumen 20 so as to be able to advance and retract. The electrode catheter 10 also includes a handle 26 attached to a proximal portion of the outer shaft 22 to support the outer shaft 22, and an electrode assembly 28, at least a portion of which is provided distal to the distal end of the outer shaft 22. As described herein, the requirement "provided distal to the distal end of the outer shaft 22" applies only if at least a portion of the electrode assembly 28 is satisfied. For example, in this embodiment, this requirement is satisfied by the entire electrode assembly 28 when the inner shaft 24 is located distal to a settling start position Pb (described below) within the advance / retract range of the inner shaft 24. On the other hand, this requirement is satisfied by a portion of the electrode assembly 28 when the inner shaft 24 is located proximal to the settling start position Pb within the advance / retract range of the inner shaft 24.

[0013] Below, the positional relationship of each component will be explained based on the assumption that the outer shaft 22 and the inner shaft 24 are not bent and extend linearly. The circumferential direction and radial direction around the center line (not shown) of the outer shaft 22 are simply referred to as the "circumferential direction" and the "radial direction." The "distal side" refers to the side of the outer shaft 22 that is farther from the surgeon's hand holding the handle 26 in the axial direction, and the "proximal side" refers to the side opposite the distal side in the axial direction. The most distal position within the range in which the inner shaft 24 can be advanced or retreated is referred to as the most distal position Pa. Figure 3 shows the inner shaft 24 in the most distal position Pa.

[0014] The handle 26 is held by the surgeon and is provided with an advance / retract operation part 26a such as a slide knob that is operated when advancing and retracting the inner shaft 24.

[0015] 3, 4, and 5. At least the distal side of the outer shaft 22 is inserted into the body. A distal end opening 30 that opens to the distal end of the outer shaft 22 is provided at the distal end of the lumen 20 of the outer shaft 22.

[0016] The inner shaft 24 is composed of at least one shaft member 24A to 24D. In this embodiment, the inner shaft 24 is illustrated as being composed of four shaft members 24A to 24D, but the number is not particularly limited. The four shaft members 24A to 24D include, in order from the distal side to the proximal side, the most distal shaft member 24A, the distal shaft member 24B, the intermediate shaft member 24C, and the proximal shaft member 24D. The multiple shaft members 24A to 24D are integrated by welding, adhesive bonding, or the like. The most distal shaft member 24A is composed of a member with a higher hardness than the distal shaft member 24B. This ensures the strength of the distal end of the inner shaft 24. Alternatively, the most distal shaft member 24A and the distal shaft member 24B may be composed of a single shaft member.

[0017] The outer shaft 22 and the inner shaft 24 are flexible and bendable. The outer shaft 22 and the inner shaft 24 (shaft members 24A to 24D) are made of various materials, including known materials for constructing catheter shafts. Examples of such materials include synthetic resins such as polyether block ether, polyamide, polyolefin, and polytetrafluoroethylene.

[0018] The electrode assembly 28 includes a plurality of splines 32 and a plurality of electrodes 34 provided on each of the plurality of splines 32. Here, an example is shown in which there are a total of four splines 32, but the number is not particularly limited. In Fig. 3, only two splines 32 are shown, and the other splines 32 are omitted.

[0019] A plurality of electrodes 34 corresponding to each of the plurality of splines 32 are provided at intervals in the longitudinal direction of the splines 32. The electrodes 34 are ring-shaped and are made of a metal (including alloys) with good electrical conductivity, such as platinum, gold, or silver.

[0020] Each of the splines 32 is configured as a flexible linear body that can be bent. The splines 32 are provided at intervals in the circumferential direction around the center line of the outer shaft 22. Each of the splines 32 has one longitudinal end (hereinafter referred to as the outer end 32a) connected to the outer shaft 22 and the other longitudinal end (hereinafter referred to as the inner end 32b) connected to the inner shaft 24. To achieve this, the splines 32 of this embodiment are connected to the respective shafts 22, 24 by their respective core wires 42 (described below). The splines 32 are connected to the respective shafts 22, 24 by adhesive bonding, welding, or the like. To achieve this, the splines 32 may be connected to the respective shafts 22, 24 directly or via other members fixed to the respective shafts 22, 24. The splines 32 of this embodiment are inserted into first insertion holes 36 provided in the outer shaft 22, and then the outer end 32a is connected to the outer shaft 22. The spline 32 of this embodiment is inserted into a second insertion hole 38 provided in the inner shaft 24, and then the inner end portion 32b thereof is connected to the intermediate shaft member 24C.

[0021] The spline 32 has an exposed portion 40 that is exposed to the outside of the inner shaft 24 and the outer shaft 22. The term "exposed" here refers to the condition that the inner shaft 24 is positioned anywhere within the range of its advance / retract movement. For example, when the inner shaft 24 is in the retracted position P2 (described later), a specific portion of the spline 32 located within the lumen 20 of the outer shaft 22 is located on the spline 32. In this case, when the inner shaft 24 is in the protruding position Pa1 (described later), if the specific portion of the spline 32 is exposed outside the lumen 20 of the outer shaft 22, the specific portion is treated as part of the exposed portion 40. The portion of the spline 32 that becomes the exposed portion 40 does not change depending on the position of the inner shaft 24 within the range of its advance / retract movement. Hereinafter, the end of the exposed portion 40 of the spline 32 on the outer shaft 22 side will be referred to as the outer-side exposed end portion 32c, and the end on the inner shaft 24 side will be referred to as the inner-side exposed end portion 32d.

[0022] The spline 32 includes a core wire 42 that forms the core of the spline 32, and an outer tube 44 that covers the core wire 42. The core wire 42 is made of, for example, metal, resin, or the like. The outer tube 44 is made of, for example, resin, or the like. A plurality of conductors (not shown) that are electrically connected to the plurality of electrodes 34 corresponding to the spline 32 are inserted through the outer tube 44. The plurality of conductors are drawn into the outer shaft 22 via the outer end 32a of the spline 32 and electrically connected to an external electrical device. The external electrical device cooperates with the plurality of electrodes 34 to supply electricity for treatment to the treatment target portion 16 of the living body, process biosignals (cardiac potential, etc.) from the treatment target portion 16, and the like.

[0023] Please refer to Figures 6 to 8. Figure 6 shows the inner shaft 24 at the most distal position Pa, Figure 8 shows the inner shaft 24 at a retraction start position Pb, which will be described later, and Figure 7 shows the inner shaft 24 in a state between the most distal position Pa and the retraction start position Pb.

[0024] The inner shaft 24 can be advanced and retracted between a protruding position P1, where the inner shaft 24 protrudes from the distal end opening 30 of the outer shaft 22, and a retracted position P2, where the inner shaft 24 is retracted to the rear side of the distal end opening 30. Here, the "retracted position P2" refers to the position rearward of the position where the distal end 24a of the inner shaft 24 and the distal end opening 30 of the outer shaft 22 overlap. When the inner shaft 24 is retracted, the position where the inner shaft 24 begins to retract to the rear side of the distal end opening 30 is referred to as the retraction start position Pb. The retraction start position Pb is part of the retraction position P2. FIG. 8 shows an example in which the inner shaft 24 is at the retraction start position Pb, but the inner shaft 24 of this embodiment can be retracted further rearward than the retraction start position Pb.

[0025] The exposed portions 40 of the splines 32 can expand or contract radially in response to the advancement and retreat of the inner shaft 24. The exposed portions 40 contract by contracting radially inward and expand by bulging radially outward. When the inner shaft 24 is in the protruding position P1, the multiple splines 32 of this embodiment form a basket structure that can expand or contract in response to the advancement and retreat of the inner shaft 24. The basket structure is formed by the multiple splines 32 surrounding an inner space. It can also be said that the multiple splines 32 form a basket structure when the inner shaft 24 is located anywhere within the advancement and retreat range.

[0026] The outer diameter of the electrode assembly 28 of this embodiment can be adjusted by the expansion or contraction of the multiple splines 32 in accordance with the advancement and retraction of the inner shaft 24. Here, the outer diameter of the electrode assembly 28 refers to the radius of a circle circumscribing the electrode assembly 28 with its center at the center line (not shown) of the outer shaft 22, as viewed from the advancement and retraction direction Da of the inner shaft 24.

[0027] The position of the inner shaft 24 when the outer diameter of the basket-structured electrode assembly 28 is at its maximum is referred to as the maximum outer diameter position Pc. Also, consider an end range Rb located at the end of the movable range Ra of the inner shaft 24, from the distalmost position Pa to the retraction start position Pb, near the retraction start position Pb. The end range Rb here refers to the range from the retraction start position Pb to the length of the movable range Ra in the forward / retraction direction, divided into four equal parts. In FIG. 6, each position Pa, Pb, and Pc is indicated by 24a (at Pa), etc., using the position of the distal end 24a of the inner shaft 24. For example, 24a (at Pc) indicates the position of the distal end 24a when the inner shaft 24 is at the maximum outer diameter position Pc. When the distal end 24a of the inner shaft 24 is located within the end range Rb in FIG. 6, this means that the inner shaft 24 is in the end range Rb.

[0028] The inventors of the present application have found that when the multiple splines 32 are configured to expand or contract in response to the advancement or retreat of the inner shaft 24, the maximum outer diameter position Pc is located somewhere within the end region Rb, although this may vary due to factors such as the flexibility of the splines 32. In particular, they have found that in many cases, the maximum outer diameter position Pc of the inner shaft 24 is located very close to the retraction start position Pb within the end region Rb of the inner shaft 24. When the electrode assembly 28 is configured as described above, as the inner shaft 24 retracts from the distal-most position Pa to the maximum outer diameter position Pc, the multiple splines 32 expand, thereby increasing the outer diameter. Furthermore, as the inner shaft 24 retracts from the maximum outer diameter position Pc, the multiple splines 32 each contract, thereby decreasing the outer diameter of the electrode assembly 28. Note that the maximum outer diameter position Pc of the inner shaft 24 may also be the retraction start position Pb.

[0029] Each of the multiple splines 32 is shaped so that it folds back at its distal end in the advancing / retracting direction Da of the inner shaft 24 when the inner shaft 24 is located anywhere within its range of movement. In this embodiment, this condition is met when the splines 32 are located at all positions within the range of movement of the inner shaft 24. Here, the "distal end 32h of the spline 32" does not refer to the longitudinal end of the spline 32, but rather to the point located most distally in the advancing / retracting direction Da of the spline 32. By folding back the spline 32 in this way in the advancing / retracting direction Da of the inner shaft 24, a distal folded end 32e is provided at the distal end 32h of the spline 32. This "distal folded end 32e" refers to the boundary between two portions 36A, 36B extending in the longitudinal direction of the spline 32 from both ends of the spline 32 toward the distal end 32h. The portion of these two portions 36A, 36B that extends further in the longitudinal direction of the spline 32 toward the proximal side than the boundary between the two portions is not included in the distal folded end portion 32e.

[0030] Each of the multiple splines 32 is flexibly deformable so as to change the advance / retract directional distance La from the inner shaft 24 to the distal side flap portion 32e of the spline 32 in accordance with the advance / retract movement of the inner shaft 24. This advance / retract directional distance La increases as the inner shaft 24 retreats from the distalmost position Pa to the maximum outer diameter position Pc, and decreases as the inner shaft 24 retreats from the maximum outer diameter position Pc. This advance / retract directional distance La refers to the distance from the distal end of the inner shaft 24 to the distal end 32h of the spline 32. The advance / retract directional distance when the inner shaft 24 is at the advance / retract directional position where the advance / retract directional distance La is smallest within the advance / retract directional range of the inner shaft 24 (here, the distalmost position Pa) is referred to as the reference distance. In this case, "changing the forward / backward direction distance La" does not mean that the forward / backward direction distance La changes within a small range relative to the reference distance (for example, a range of the reference distance x 1.1 or less), but rather that the forward / backward direction distance La changes within a certain range relative to the reference distance (for example, a range of the reference distance x 1.5 or more).

[0031] As the inner shaft 24 retracts from the distalmost position Pa to the maximum outer diameter position Pc, each of the splines 32 deforms such that the position of the distal folded end 32e relative to the inner shaft 24 shifts radially outward. At this time, the distal folded end 32e of the spline 32 can shift from an extension range Sa, which is an extension of the outer shaft 22 in the advancing / retracting direction Da, to a position radially outward beyond the extension range Sa. Here, the extension range Sa refers to the range obtained by extending the entire portion of the outer shaft 22 that is radially inward from the outer circumferential surface of the outer shaft 22 in the advancing / retracting direction Da. Furthermore, as the inner shaft 24 retracts from the distalmost position Pa to the maximum outer diameter position Pc, each of the splines 32 deforms such that the position of the outermost peripheral end 32f relative to the inner shaft 24 shifts radially outward. As a result, the outer diameter of the electrode assembly 28 increases. Here, the outermost peripheral end 32f refers to the radially outermost point of the exposed portion 40 of the spline 32.

[0032] To achieve the flexible deformation of the spline 32, the spline 32 has a shape that does not have any bent portions within the extension range Sa. The bent portion here refers to a portion that maintains a bent state (folded state) even when the spline 32 deforms in response to the advancement and retreat of the inner shaft 24, as in the reference embodiment described below. If there is a bent portion within the longitudinal range of such an exposed member, the flexible deformation of the spline 32 will be significantly restricted at that bent portion.

[0033] The spline 32 of this embodiment has a shape that has no bends in the longitudinal range from the distal folded end 32e of the spline 32 to the inner end 32b. The spline 32 of this embodiment also has a shape that has no bends in the longitudinal range from the distal folded end 32e of the spline 32 to the outermost end 32f. This shape allows the spline 32 to deform while maintaining a smooth curved shape that is convex toward the distal side in the longitudinal range including the distal folded end 32e, following the advancement and retreat of the inner shaft 24 when the inner shaft 24 is in the protruding position P1. In this embodiment, the spline 32 deforms while maintaining a smooth curved shape that is convex toward the distal side in the longitudinal range from the inner end 32b of the spline 32 to the outermost end 32f. Here, the "smooth curved shape" means a shape that has no bends in that longitudinal range.

[0034] The effects of the electrode catheter 10 described above will now be described.

[0035] (A) In addition to the protruding position P1 described above, the inner shaft 24 can also be advanced and retracted up to the retracted position P2. Therefore, compared to when the inner shaft 24 can only be advanced and retracted to the protruding position P1, the range over which the inner shaft 24 can be advanced and retracted can be expanded to the retracted position P2. Consequently, compared to when the inner shaft 24 can only be advanced and retracted to the protruding position P1, the amount of deformation of the multiple splines 32 can be increased, and the degree of freedom in the shape of the electrode assembly 28 that can be adjusted by advancing and retracting the inner shaft 24 can be increased.

[0036] (B) The outer diameter of the electrode catheter 10 can be adjusted by expanding or contracting the multiple splines 32 in response to the advancement and retraction of the inner shaft 24. With this structure, as described above, a maximum outer diameter position Pc, where the outer diameter of the electrode assembly 28 is at its maximum, is typically located somewhere within the end range Rb of the movable range Ra of the inner shaft 24. As described above, the inner shaft 24 of this embodiment can expand the advancement and retraction range of the inner shaft 24 from the protruding position P1 to the retracted position P2 (retraction start position Pb). Therefore, compared to when the inner shaft 24 can only advance and retract between the protruding position P1, the inner shaft 24 can be reliably positioned at the maximum outer diameter position Pc. Consequently, the shape of the electrode assembly 28 can be adjusted so that the outer diameter of the electrode assembly 28 is reliably at its maximum outer diameter.

[0037] (C) The spline 32 is flexibly deformable so as to change the distance La of the distal folded end 32e relative to the inner shaft 24 in the advancing and retracting direction in accordance with the advancing and retracting movement of the inner shaft 24. Therefore, compared to the case where the distance La of the distal folded end 32e of the spline 32 relative to the inner shaft 24 is constant, as in the next reference embodiment, the degree of freedom in the shape of the electrode assembly 28, which is adjusted by the advancing and retracting movement of the inner shaft 24, can be increased.

[0038] 9A and 9B, an electrode catheter 100 of a reference embodiment will be described. This electrode catheter 100 differs from the electrode catheter 10 of the first embodiment in the splines 32 of the electrode assembly 28. The multiple splines 32 of the reference embodiment have a bent portion 102 in the aforementioned extension range Sa, and the bent portion 102 forms the distal folded end 32e.

[0039] In this case, even when the inner shaft 24 is advanced or retracted, the bent portion 102 at the distal folded end 32e of the spline 32 inhibits flexible deformation of the spline 32. As a result, the portion of the spline 32 from the distal folded end 32e to the inner-side exposed end 32d cannot flexibly deform, but the portion between the distal folded end 32e and the outer-side exposed end 32c can flexibly deform. In other words, in the structure of the reference embodiment, the multiple splines 32 cannot flexibly deform so as to change the advance / retract directional distance La from the inner shaft 24 to the distal folded end 32e of the spline 32 in accordance with the advance / retraction of the inner shaft 24. Therefore, as the inner shaft 24 is retracted, the advance / retract directional distance Lb from the distal folded end 32e of the spline 32 to the outer-side exposed end 32c of the spline 32 uniformly shortens. As a result, the multiple splines 32 as a whole assume a flattened shape in the advance / retract direction Da. As a result, as shown in Figure 10, when the outer diameter of the electrode assembly 28 is increased, the electrode assembly 28 can only contact the tapered portion 16a of the treatment target area 16 of the living body at a localized area near the outermost end 32f of the electrode assembly 28.

[0040] In this regard, each of the multiple splines 32 in this embodiment can flexibly deform to change the advance / retraction directional distance La from the inner shaft 24 to the distal folded end 32e of the spline 32 in accordance with the advance / retraction of the inner shaft 24. Therefore, when the inner shaft 24 is retracted, the spline 32 can flexibly deform so as to increase the advance / retraction directional distance La from the inner shaft 24 to the distal folded end 32e of the spline 32. This prevents the advance / retraction directional distance Lb from the distal folded end 32e of the spline 32 to the outer exposed end 32c of the spline 32 from uniformly shortening as the inner shaft 24 is retracted, and allows the advance / retraction directional distance Lb to be maintained at a certain length. As a result, the multiple splines 32 as a whole are less likely to become flat in the advance / retraction direction Da. 1, when the outer diameter of the electrode assembly 28 is increased, the electrode assembly 28 can come into contact with the tapered portion 16a of the treatment target portion 16 of the living body at portions other than the outermost peripheral end 32f of the electrode assembly 28. Therefore, even when the outer diameter of the electrode assembly 28 is increased, it is easy to ensure the contact area of ​​the electrode assembly 28 with the treatment target portion 16 of the living body.

[0041] Other features of the electrode catheter 10 will now be described. Reference is made to FIGS. 3 and 11. At least one of the outer shaft 22 and the inner shaft 24 has irrigation ports 50A, 50B for injecting irrigation fluid. In this embodiment, the outer shaft 22 has a first irrigation port 50A, and the inner shaft 24 has a second irrigation port 50B. The first irrigation port 50A opens at the distal end surface of the outer shaft 22, and the distal end opening 30 of the outer shaft 22 also serves as the first irrigation port 50A. The second irrigation port 50B opens at the distal end surface of the inner shaft 24. Irrigation fluid is injected distally from each of the irrigation ports 50A, 50B. Irrigation fluid is supplied to each of the irrigation ports 50A, 50B from an external fluid supply device through irrigation fluid supply paths (not shown) provided in the handle 26, each of the shafts 22, 24, etc.

[0042] The irrigation fluid is, for example, saline. The irrigation fluid is irrigated, for example, to cool the treatment target area 16 and the electrode assembly 28 of the living body and to promote blood flow around the electrode assembly 28. When ablation is performed using the electrode assembly 28, the treatment target area 16 and the electrode assembly 28 are heated by electricity output from the electrode assembly 28. By cooling the heated treatment target area 16 and the like with irrigation fluid, excessive temperature rise can be avoided. When the electrode assembly 28 is placed in a location where blood is present, such as the heart or blood vessels, blood stagnation around the electrode assembly 28, which has a complex shape, increases the risk of thrombus formation. By using irrigation fluid to promote the flow of blood that would otherwise stagnate, the risk of thrombus formation can be reduced.

[0043] Let us consider a case in which the inner shaft 24 can only move forward and backward through the protruding position P1. In this case, for example, when the inner shaft 24 is at the distalmost position Pa (see FIG. 6 ), the inner-side exposed end 32d of the spline 32 moves away from the first irrigation port 50A of the outer shaft 22. This causes a problem in that the irrigation liquid injected from the first irrigation port 50A does not easily reach the area around the inner-side exposed end 32d of the spline 32. Furthermore, in this case, the outer-side exposed end 32c of the spline 32 moves away from the second irrigation port 50B (not shown) of the inner shaft 24. This causes a problem in that the irrigation liquid injected from the second irrigation port 50B does not easily reach the area around the outer-side exposed end 32c of the spline 32.

[0044] (D) In ​​this regard, as described above, the inner shaft 24 of this embodiment can be advanced and retracted to the retracted position P2 in addition to the protruding position P1. Therefore, as shown in FIG. 11 , by positioning the inner shaft 24 at the retracted position P2 (particularly the retraction start position Pb), the exposed ends 32c, 32d of the spline 32 can be brought closer to the irrigation ports 50A, 50B of the outer shaft 22 and the inner shaft 24. This in turn makes it easier for the irrigation liquid injected from the irrigation ports 50A, 50B to sufficiently reach the areas around the exposed ends 32c, 32d of the spline 32. In relation to the effect of (D), it is sufficient that only one of the outer shaft 22 and the inner shaft 24 has the irrigation ports 50A, 50B.

[0045] (E) As described above, the spline 32 is flexibly deformable so as to change the relative position of the distal folded end 32e with respect to the inner shaft 24 in response to the advancement and retreat of the inner shaft 24. This allows the portion of the spline 32 from the inner exposed end 32d to the outermost end 32f to have a smooth curved shape. When irrigation fluid is injected distally from the irrigation ports 50A, 50B of the outer shaft 22 and the inner shaft 24 into the curved portion of the spline 32, the curved portion allows the irrigation fluid to be smoothly guided in the direction Db. In particular, the irrigation fluid can be guided more smoothly than when the spline 32 has a bent portion. Therefore, the irrigation fluid injected from the irrigation ports 50A, 50B can reach a wider area. In relation to the effect of (E), only one of the outer shaft 22 and the inner shaft 24 needs to have the irrigation ports 50A, 50B. Furthermore, although the case where the inner shaft 24 is in the retracted position P2 has been illustrated and described here, the effect (E) can also be obtained when the inner shaft 24 is in the protruding position P1.

[0046] Another feature of the electrode catheter 10 will now be described. Refer to FIG. 6 . The distal folded end 32e of each of the multiple splines 32 is located distally of the distal end 24b of the inner shaft 24 or a member integral with the distal end 24b of the inner shaft 24. Here, the term "integral member" refers, for example, to a member that is integrally attached to the inner shaft 24 and to which the inner ends 32b of each of the multiple splines 32 are connected. When there is no member integral with the distal end 24b of the inner shaft 24, as in this embodiment, the distal folded end 32e of each of the multiple splines 32 may be located distally of the distal end 24b. Furthermore, when there is a member integral with the distal end 24b of the inner shaft 24, the distal folded end 32e of each of the multiple splines 32 may be located distally of the integral member.

[0047] (F) This results in a structure in which other components of the electrode catheter 10 do not protrude distally beyond the distal folded end 32e of each of the multiple splines 32. Therefore, compared to when the components of the electrode catheter 10 protrude distally beyond the multiple splines 32, the electrode assembly 28 can be brought into contact with the treatment target portion 16 of the living body located on the distal side without interfering with those components. This in turn makes it easier to increase the contact area of ​​the electrode assembly 28 with the treatment target portion 16 of the living body.

[0048] (G) The core wire 42 is exposed and not covered by the outer tube 44 at least at the inner-side exposed end 32d of the spline 32. The exposed portion of the core wire 42 is more flexible and deformable than the portion of the core wire 42 covered by the outer tube 44. Therefore, by exposing the core wire 42 at the inner-side exposed end 32d of the spline 32, the flexibility of the inner-side exposed end 32d can be increased. Therefore, when the inner shaft 24 approaches the most distal position Pa, the inner-side exposed end 32d of the spline 32 is more likely to bend and deform significantly. Accordingly, the portion of the exposed portion 40 of the spline 32 closer to the outer shaft 22 than the distal-side folded end 32e can be more easily brought closer to the inner shaft 24, making it easier to reduce the outer diameter of the electrode assembly 28. As a result, when the electrode assembly 28 is housed in a sheath, reducing the outer diameter of the electrode assembly 28 also reduces the outer diameter of the sheath. This sheath is used to house the electrode assembly 28 beforehand when the electrode assembly 28 is inserted close to the treatment target portion 16 of the living body.

[0049] A step 32g is formed on the spline 32 by the end surface of the outer tube 44 on the inner shaft 24 side. Blood tends to stagnate around this step 32g of the spline 32. Therefore, it is preferable to provide the step 32g of the spline 32 as close as possible to the end of the exposed portion 40 of the spline 32 on the inner shaft 24 side, where irrigation fluid injected from the irrigation ports 50A, 50B can easily reach. From this perspective, the exposed portion of the core wire 42 is preferably provided only on the inner shaft 24 side of the distal folded end 32e of the spline 32. This condition only needs to be met when the inner shaft 24 is at the most distal position Pa. This makes it easier for irrigation fluid injected from the irrigation ports 50A, 50B to reach the step 32g of the core wire 42, thereby suppressing thrombus formation around the step 32g.

[0050] (H) See FIG. 3 . Of the core wire 42 and the outer tube 44, only the core wire 42 is inserted into at least one of the inner shaft 24 and the outer shaft 22. This means that the outer tube 44 is not inserted into at least one of the inner shaft 24 and the outer shaft 22. In this embodiment, only the core wire 42 is inserted into both the inner shaft 24 and the outer shaft 22. To satisfy this condition, the core wire 42 is inserted into the first insertion hole 36 of the outer shaft 22 toward the rear, and into the second insertion hole 38 of the inner shaft 24 toward the rear. Alternatively, only the core wire 42 may be inserted into only one of the inner shaft 24 and the outer shaft 22. This avoids the need for a shaft without the outer tube 44 inserted therethrough, compared to when the outer tube 44 is inserted in addition to the core wire 42. In this embodiment, it is possible to avoid the need for a shaft with a large outer diameter.

[0051] (I) The inner shaft 24 has a protruding region 24c that protrudes from the outer shaft 22 when the inner shaft 24 is at the distal-most position Pa. The spline 32 is inserted into the inner shaft 24 over at least the entire range of the advancing / retracting direction in which the protruding region 24c is located. To satisfy this condition, it is sufficient that one of the components of the spline 32 is inserted into the protruding region 24c of the inner shaft 24. In this embodiment, the core wire 42 of the spline 32 is inserted into the protruding region 24c. Alternatively, both the core wire 42 and the outer tube 44 of the spline 32 may be inserted into the protruding region 24c, or the outer tube 44 may be inserted into the protruding region 24c. By inserting the spline 32 into such a range of the advancing / retracting direction that includes the protruding region 24c, the protruding region 24c can be reinforced by the spline 32.

[0052] (Second embodiment) See Figures 12 and 13. The electrode catheter 10 of this embodiment differs from the first embodiment mainly in the configuration of the multiple splines 32. The same configuration as the first embodiment applies except for the electrode assembly 28. Although not shown here, the inner shaft 24 can be advanced and retracted between a protruding position P1 and a retracted position P2, just like the first embodiment.

[0053] The electrode assembly 28 of this embodiment has a total of four splines 32. Hereinafter, when distinguishing between the four splines 32, the splines 32 will be prefixed with "first, second, third, fourth" and the reference numerals will be suffixed with "-A, -B, -C, -D."

[0054] The splines 32-A to 32-D can form a flower structure when the inner shaft 24 is located anywhere within its range of movement. In this embodiment, this condition is met when the inner shaft 24 is located at any position within its range of movement. When the splines 32-A to 32-D form a flower structure, each of the splines 32-A to 32-D has petal-shaped portions 60 that protrude radially outward. Each of the splines 32-A to 32-D that has the petal-shaped portions 60 is folded back radially to form an outer circumferential folded end 62 at the outermost end 32f of the spline 32. The "outer circumferential folded end 62" here refers to the boundary between two portions 64A, 64B that extend in the longitudinal direction of the spline 32 from both ends of the spline 32 toward the outermost end 32f. Each of the splines 32-A to 32-D has two portions 64A, 64B: a first-end portion 64A extending from the outer-periphery folded end 62 toward the first end, and a second-end portion 64B extending from the outer-periphery folded end 62 toward the second end. When viewed from the forward / backward direction Da (as viewed from the perspective of FIG. 12), the petal-shaped portion 60 has a hoop shape with a cutout on the radially inner side. At the base of the petal-shaped portion 60, the first-end portion 64A is located to one circumferential side (here, clockwise) of the second-end portion 64B.

[0055] Each spline 32-A to 32-D is positioned so that it can intertwine with at least one other spline 32-A to 32-D adjacent to it on one circumferential side from the circumferentially inner side. It can also be said that each spline 32-A to 32-D is positioned so that it intersects with at least one other spline 32-A to 32-D adjacent to it on one circumferential side when viewed from the forward / backward direction Da (as viewed from the perspective of FIG. 12). The splines 32-A to 32-D of this embodiment are positioned so that they can intertwine with each of the other individual splines 32-A to 32-D adjacent to them on both circumferential sides from the circumferentially inner side. For example, the first end portion 64A of the first spline 32-A is positioned so that it can intertwine with a second end portion 64B of another second spline 32-B adjacent to it on one circumferential side from the circumferentially inner side. Furthermore, the second end portion 64B of the first spline 32-A is positioned so that it can intertwine with the first end portion 64A of another adjacent fourth spline 32-D on the other circumferential side from the circumferentially inner side. Here, "circumferentially inner side" refers to the side (counterclockwise here) of the second end portion 64B of the same spline 32-A to 32-D in the first end portion 64A, and refers to the side (clockwise here) of the first end portion 64B of the same spline 32-A to 32-D in the second end portion 64B. All of the multiple splines 32-A to 32-D constituting the electrode assembly 28 satisfy the conditions described above. Furthermore, the first end portion 64A and the second end portion 64B of adjacent splines 32-A to 32-D are positioned so that they can intertwine with each other in the exposed portion 40.

[0056] As viewed from the advance / retract direction Da, an angular range θ is assumed from the end of the exposed portion 40 of the first end portion 64A of one spline 32 to the end of the exposed portion 40 of the second end portion 64B of another adjacent spline 32. This angular range θ is a range centered on the center line of the outer shaft 22 and defined by two radial lines tangent to the ends of the two referenced exposed portions 40 from the circumferential outside. This angular range θ is the same size for all splines 32. Here, "same size" means being the same or approximately the same.

[0057] The effects of the electrode catheter 10 described above will be explained. Consider a case in which an external force F1 acts on a first spline 32-A that is positioned so as to intertwine with the second spline 32-B, causing the first spline 32-A to move away from the second spline 32-B in the circumferential direction. In this case, the first spline 32-A intertwines with the second spline 32-B in the circumferential direction, restricting the movement of the first spline 32-A away from the second spline 32-B in the circumferential direction. This makes it difficult for the first spline 32-A to move away from the second spline 32-B in the circumferential direction, making it easier to maintain the circumferential spacing between adjacent first splines 32-A and second splines 32-B. Here, the effects achieved by the relationship between the first spline 32-A and the second spline 32-B adjacent to it on one circumferential side have been described. However, similar effects can also be achieved by the relationship between another spline 32 and another spline 32 adjacent to it on one circumferential side.

[0058] Next, consider a case where an external force F2 acts on the first spline 32-A, causing it to approach the second spline 32-D in the circumferential direction. In this case, the first spline 32-A becomes entangled with the fourth spline 32-D in the circumferential direction, restricting the movement of the first spline 32-A away from the fourth spline 32-D in the circumferential direction. This makes it difficult for the first spline 32-A to approach the second spline 32-B in the circumferential direction, making it easier to maintain the circumferential distance between the second spline 32-B and the first spline 32-A. The same applies to the circumferential distance between the first spline 32-A and the fourth spline 32-D. Here, the effect achieved in the relationship between the first spline 32-A and the fourth spline 32-D adjacent to it on the other circumferential side has been described. However, a similar effect can be achieved in the relationship between any other spline 32 and another spline 32 adjacent to it on the other circumferential side.

[0059] Another feature of the electrode catheter 10 of this embodiment will be described. Consider a first end portion 64A of one spline 32-A to 32-D and a second end portion 64B of another spline 32-A to 32-D that are adjacent in the circumferential direction. For example, the first end portion 64A of the first spline 32-A and the second end portion 64B of the second spline 32-B. One of these (in this example, the first end portion 64A of the first spline 32-A) is connected to the outer shaft 22. The other of these (in this example, the second end portion 64B of the second spline 32-B) is connected to the inner shaft 24. The outer shaft 22 is connected to the aforementioned outer end portion (not shown), which forms part of the end portion 64A of the spline 32 in question. The inner shaft 24 is connected to the aforementioned inner end portion (not shown), which forms part of the end portion 64B of the spline 32 in question.

[0060] See Figure 14. The inner shaft 24 can be retracted further back than the distal end opening 30 of the outer shaft 22. In other words, the inner shaft 24 can be advanced and retracted from the retracted position P2. By retracting the inner shaft 24 in this manner, the second end portion 64B of the spline 32 connected to the inner shaft 24 can be retracted into the lumen 20 of the outer shaft 22. This reduces the outer diameter of the petal-shaped portion 60 formed by the spline 32, thereby reducing the outer diameter of the entire electrode assembly 28. In other words, the outer diameter of the electrode assembly 28 can be adjusted.

[0061] Furthermore, the first end portion 64A of the spline 32 connected to the outer shaft 22 can guide the second end portion 64B of the spline 32 connected to the inner shaft 24 in the direction Dc (counterclockwise in this case) toward the inside in the circumferential direction of the spline 32. As a result, even if the spacing between the portions near the outer circumferential folded end portions 62 of adjacent splines 32 becomes excessively wide, it is easy to correct this so that the spacing becomes closer by returning the inner shaft 24 to its original position before being retracted (for example, the fitting start position Pb in FIG. 13).

[0062] Note that the same effects as those described in (A) can be obtained in this embodiment as well. Also, the configurations described in (B) to (I) of the first embodiment may be applied to this embodiment as well.

[0063] When the above-described flower structure is employed, the inner shaft 24 may be provided rotatably relative to the outer shaft 22. In this case, the handle 26 may be provided with a rotation operating part that is operated when rotating the inner shaft 24. This makes it possible to adjust the width and outer diameter of the petal-shaped portions 60 of the spline 32 by rotating the inner shaft 24.

[0064] Alternatively, the inner shaft 24 may be provided so as to be non-rotatable relative to the outer shaft 22. To achieve this, the lumen 20 of the outer shaft 22 and the outer periphery of the inner shaft 24 may be shaped to limit the rotation of the inner shaft 24 relative to the outer shaft 22 (for example, an oval shape).

[0065] Incidentally, even when the plurality of splines 32 form a basket structure as in the first embodiment, the inner shaft 24 may be provided to be rotatable. In this case, by rotating the inner shaft 24, it is possible to form both the basket structure and the flower structure.

[0066] Next, variations of the components described above will be described.

[0067] The electrode catheter 10 may not include the irrigation ports 50A, 50B. The multiple splines 32 may have a shape with a bent portion in the extension range Sa of the inner shaft 24. The distal folded end 32e of each of the multiple splines 32 may not be provided in a position shifted distally from the distal end 24b of the inner shaft 24 or a member integral with the distal end of the inner shaft 24. The splines 32 may be inserted into the inner shaft 24 only in a portion of the advancing / retracting direction range where the protruding regions 24c are located, or may not be inserted into the inner shaft 24 at all.

[0068] The spline 32 may have only the outer tube 44 without the core wire 42. Both the core wire 42 and the outer tube 44 may be inserted through both the inner shaft 24 and the outer shaft 22. The core wire 42 may also be covered by the outer tube 44 at the inner-side exposed end 32d of the spline 32. This allows the inner-side exposed end 32d of the spline 32 to be reinforced by the outer tube 44. In this case, too, only the core wire 42 of the spline 32 may be inserted through the outer tube 44.

[0069] In the second embodiment, the splines 32 may be provided at positions where they can intertwine only with other adjacent splines 32 on one circumferential side from the circumferential inside. It is sufficient that at least some of the multiple splines 32 are provided at positions where they can intertwine with other adjacent splines 32 on one circumferential side, and it is not necessary for all of the splines 32 to satisfy this condition. In the second embodiment, the inner shaft 24 may be unable to retract further beyond the distal end opening 30 of the lumen 20.

[0070] The above-described embodiments and variations are merely examples. The abstract technical concepts should not be interpreted as being limited to the content of the embodiments and variations. Many design changes are possible in the content of the embodiments and variations, such as changing, adding, or deleting components. In the above-described embodiments, the term "embodiment" is used to emphasize that such design changes are possible. However, design changes are also permitted even in content not so marked. Hatching on cross sections in the drawings does not limit the material of the hatched object. The structures and numerical values ​​referred to in the embodiments and variations naturally include those that can be considered identical when manufacturing errors, etc. are taken into account.

[0071] If the technical ideas embodied in the above embodiments and modified forms are generalized, it can be said that they include the technical ideas described in the following third item in addition to the first and second items mentioned above.

[0072] The third item is an electrode assembly comprising an outer shaft having a lumen formed therein, an inner shaft inserted into the lumen so as to be able to advance and retreat, and an electrode assembly having at least a portion disposed distal to the distal end of the outer shaft, wherein the electrode assembly has a plurality of splines having one end connected to the outer shaft and the other end connected to the inner shaft, and when the inner shaft is at any position within the advance and retreat range, each of the plurality of splines has a shape having petal-shaped portions protruding radially outward in the radial direction when viewed from the advance and retreat direction, and one of the splines is disposed in a position where it can entangle from the circumferential inside with another spline adjacent to at least one circumferential side.

[0073] One of the purposes of the electrode catheter in the third item is to provide a technique that makes it easier to maintain the circumferential spacing between adjacent splines.

[0074] When realizing the electrode catheter of the first item, each of the multiple splines does not have to have a shape including a distal folded end, as in the second item. When realizing the electrode catheter of the second item, the inner shaft does not have to be able to advance and retract between the extended position and the retracted position, as in the first item. For example, the inner shaft may be able to advance and retract only at the extended position. When realizing the electrode catheter of the third item, the inner shaft does not have to be able to advance and retract between the extended position and the retracted position, as in the first item. For example, to achieve this, the inner shaft may be able to advance and retract only at the retracted position. When realizing the electrode catheter of the third item, each of the multiple splines does not have to have a shape including a distal folded end, as in the second item. For example, each of the multiple splines may only have a shape including the petal-shaped portion described above.

[0075] Any combination of the above components is also effective. For example, any description of another embodiment may be combined with the embodiment, or any description of an embodiment and another modified embodiment may be combined with the modified embodiment. The same applies to realizing the electrode splines of the first to third items. [Explanation of symbols]

[0076] 10...electrode catheter, 20...lumen, 22...outer shaft, 22...shaft, 24...inner shaft, 24a...distal end, 24b...distal end, 24c...protruding region, 28...electrode assembly, 30...distal end opening, 32...spline, 32e...distal folded end, 34...electrode, 40...exposed portion, 42...core wire, 44...outer tube, 50A, 50B...irrigation port, 60...petal-shaped portion, 64A...first end portion, 64B...second end portion.

Claims

1. an outer shaft having a lumen formed therein; an inner shaft that is inserted into the lumen so as to be able to advance and retreat; an electrode assembly at least partially disposed distal to the distal end of the outer shaft; the electrode assembly includes a plurality of splines, one end of which is connected to the outer shaft and the other end of which is connected to the inner shaft; The electrode catheter is configured such that the inner shaft is movable between a protruding position where it protrudes from a distal end opening provided at the distal end of the lumen and a retracted position where it is retracted to the rear side of the distal end opening.

2. 2. The electrode catheter according to claim 1, wherein the outer diameter of the electrode assembly is adjustable by the plurality of splines expanding or contracting radially in response to the advancement or retreat of the inner shaft.

3. The electrode catheter of claim 1 , wherein at least one of the outer shaft and the inner shaft comprises an irrigation port for infusing an irrigation fluid.

4. 2. The electrode catheter according to claim 1, wherein each of the plurality of splines is shaped so as to bend back at the distal end of the spline in the advancing / retracting direction of the inner shaft when the inner shaft is positioned anywhere within its advancing / retracting range.

5. 5. The electrode catheter according to claim 4, wherein each of the plurality of splines is flexibly deformable so as to change the distance in the advancing / retracting direction from the inner shaft to the distal folded end of the spline in accordance with the advancing / retracting movement of the inner shaft.

6. 6. The electrode catheter according to claim 5, wherein the spline has a shape that has no bends in a range extending in the advancing / retracting direction of the outer shaft when the inner shaft is in the protruding position.

7. 2. The electrode catheter of claim 1, wherein at least one of the outer shaft and the inner shaft includes an irrigation port for injecting irrigation fluid distally from a distal end thereof.

8. The electrode catheter according to claim 4, wherein the distal folded end of each of the plurality of splines is located at a position distal to the distal end of the inner shaft or a member integral with the distal end of the inner shaft.

9. The spline includes a core wire and an outer tube that covers the core wire, the spline includes an exposed portion that is exposed to the outside of the inner shaft and the outer shaft, The electrode catheter according to claim 1 , wherein the core wire is exposed at least at an end of the exposed portion on the inner shaft side.

10. The spline includes a core wire and an outer tube that covers the core wire, The electrode catheter according to claim 1 , wherein only the core wire of the core wire and the outer tube is inserted inside at least one of the inner shaft and the outer shaft.

11. the inner shaft includes a protruding region that protrudes from the outer shaft when the inner shaft is at the distalmost position within a range in which the inner shaft can be advanced or retreated, The electrode catheter according to claim 1 , wherein the spline is inserted through the inner shaft at least over the entire range of the protruding region in the advancing and retracting direction.

12. When the inner shaft is positioned anywhere within a range in which the inner shaft can be advanced or retreated, each of the plurality of splines has a shape including petal-shaped portions that protrude radially outward in a radial direction as viewed from the direction in which the inner shaft is advanced or retreated, 2. The electrode catheter according to claim 1, wherein one of the splines is provided at a position where it can be entangled with another of the splines adjacent to at least one side in the circumferential direction from the circumferentially inner side.

13. An electrode catheter as described in claim 12, wherein one of the splines is entangled with the other splines from the circumferential inside, thereby restricting movement away from the other splines in the circumferential direction.

14. The electrode catheter according to claim 12, wherein the first spline is provided at a position where it can be entangled with other splines adjacent to it on both sides in the circumferential direction from the inside in the circumferential direction.

15. the spline includes a first end portion located closer to the first end than the outer circumferential folded end of the spline, and a second end portion located closer to the second end than the outer circumferential folded end, a first end portion of the one spline is provided at a position where it can be entangled with a second end portion of the other spline from the circumferentially inner side, one of a first end portion of the one spline and a second end portion of the other spline is connected to the outer shaft, and the other is connected to the inner shaft; The electrode catheter according to claim 12, wherein the inner shaft is retractable further back than the distal end opening of the lumen.

16. an outer shaft having a lumen formed therein; an inner shaft that is inserted into the lumen so as to be able to advance and retreat; an electrode assembly at least partially disposed distal to the distal end of the outer shaft; the electrode assembly includes a plurality of splines, one end of which is connected to the outer shaft and the other end of which is connected to the inner shaft; When the inner shaft is positioned anywhere within a range in which the inner shaft can be advanced or retreated, each of the plurality of splines has a shape including petal-shaped portions that protrude radially outward in a radial direction as viewed from the direction in which the inner shaft is advanced or retreated, one spline is provided at a position where it can be entangled with another spline adjacent to at least one side in the circumferential direction from the inner side in the circumferential direction, An electrode catheter in which one of the splines is entangled with another of the splines from the circumferentially inner side, thereby restricting movement of the one of the splines away from the other of the splines in the circumferential direction.

Images