WO2023021618A1

WO2023021618A1 - Electrode catheter

Info

Publication number: WO2023021618A1
Application number: PCT/JP2021/030207
Authority: WO
Inventors: 洋平鈴木
Original assignee: 日本ライフライン株式会社
Priority date: 2021-08-18
Filing date: 2021-08-18
Publication date: 2023-02-23

Abstract

The purpose of the present invention is to provide an electrode catheter capable of preventing an abnormal temperature rise around the connecting portion between a catheter shaft and a tip electrode and capable of uniformly irrigating the entire surface of the tip electrode. An electrode catheter (100) according to the present invention comprises a catheter shaft (10) having lumens (11L, 12L) serving as liquid flow paths, and a tip electrode (30) made of a porous material and connected to the distal end side of the catheter shaft, wherein the catheter shaft has a distal reduced-diameter portion (101) reducing in diameter in the distal end direction, the tip electrode is a hollow structure that has a proximal portion (32) enlarging in diameter from the distal end of the distal reduced-diameter portion in the distal end direction and a distal portion (31) reducing in diameter in the distal end direction and that has an internal space (36) communicating with the lumens of the catheter shaft, and the wall thickness of the tip electrode surrounding this internal space is substantially uniform throughout the proximal portion and the distal portion.

Description

electrode catheter

The present invention relates to an electrode catheter, and more specifically, a tip electrode made of a porous material is attached to the distal end side of a catheter shaft, and the surface of the tip electrode can be irrigated with a liquid such as physiological saline. It relates to electrode catheters.

Electrode catheters such as ablation catheters are equipped with an irrigation mechanism in order to cool the tip electrode, which has become hot during cauterization, and to prevent the formation of thrombi on the surface of the tip electrode. .

As an electrode catheter equipped with an irrigation mechanism, it consists of a catheter shaft having a central lumen serving as a liquid flow path and a conductive porous material (porous metal) connected to the tip side of this catheter shaft. A tip electrode having a tip electrode has been introduced (see Patent Document 1).

The tip electrode that constitutes the electrode catheter described in Patent Document 1 has a cylindrical portion located on the proximal end side and is fixed while being inserted into the central lumen from the tip opening of the central lumen, thereby forming a catheter shaft. connected to the tip of the
Disclosed as the shape of the tip electrode (the electrode portion that appears in the appearance excluding the cylindrical portion) is a cannonball shape (Fig. 3 of the same document), a cylindrical shape (Figs. 4 and 5), a bulbous shape (Fig. 2), and the like. It is

The tip electrode is composed of a porous material (porous metal) that allows liquid to pass through. For this reason, the liquid supplied to the central lumen of the catheter shaft is permeated into the tip electrode from the base end surface of the cylindrical portion inserted in the central lumen, and then exuded to the surface of the tip electrode to perform irrigation. be able to.

Japanese Patent No. 3606328

The electrode catheter described in Patent Document 1 has the following problems.
(1) At the junction (boundary) between the catheter shaft and the tip electrode, an edge is inevitable due to the step between the outer peripheral surface of the cylindrical portion inserted into the central lumen of the catheter shaft and the outer peripheral surface of the electrode portion that appears externally. is formed. During ablation treatment, when the connection between the catheter shaft and the tip electrode comes into contact with body tissue, the current density at the edge becomes extremely high, causing an abnormal temperature rise around the connection and rapid thrombus formation. There is a risk.

(2) In a tip electrode made of a solid porous material, it takes time for a liquid that has permeated the inside of the electrode from the base end surface of the cylindrical portion to move in the axial direction inside the electrode and reach the electrode surface at the tip portion. It takes a rather long time, and because of this, the surface of the tip portion of the tip electrode cannot be sufficiently irrigated.

(3) With tip electrodes that have different outer diameters depending on the position in the axial direction, there is variation in the time it takes for the liquid that has permeated the inside of the electrode to seep out to the electrode surface. is longer than the time required for the liquid to reach the electrode surface in the portion with the small outer diameter), and as a result, the electrode surface in the portion with the large outer diameter cannot be sufficiently irrigated.

The present invention has been made based on the circumstances as described above.
An object of the present invention is to prevent abnormal temperature rise around the connecting portion (boundary) between the catheter shaft and the tip electrode during ablation treatment, and to An object of the present invention is to provide an electrode catheter that can evenly irrigate the entire surface of the tip electrode, including the .

(1) The electrode catheter of the present invention comprises a catheter shaft having a lumen serving as a fluid flow path, and a tip electrode made of a porous material connected to the tip side of the catheter shaft,
The tip electrode has a proximal portion whose diameter increases in the distal direction from the distal end of the catheter shaft, and a distal portion which continues to the proximal portion and decreases in diameter in the distal direction. A hollow structure in which a communicating internal space is formed,
A wall thickness of the tip electrode surrounding the interior space is characterized by being substantially uniform throughout the proximal portion and the distal portion.
Here, "substantially uniform" means that the variation in wall thickness [(maximum wall thickness-minimum wall thickness)/average wall thickness] is within ±20%.

According to the electrode catheter having such a configuration, since the base end portion of the tip electrode is expanded in the distal direction, the boundary between the tip electrode and the catheter shaft is prevented from coming into contact with body tissue during ablation treatment. As a result, it is possible to prevent an abnormal temperature rise from occurring around the boundary.

In addition, although the tip electrode is made of a porous material that allows liquid to permeate (move), an internal space communicating with the lumen of the catheter shaft is intentionally formed in the tip electrode. The substantially uniform wall thickness of the electrode throughout the proximal and distal portions allows for uniform irrigation of the entire surface of the tip electrode, including the distal portion and portions of large outer diameter.

(2) In the electrode catheter of the present invention, the catheter shaft has a tip-reduced diameter portion whose diameter is reduced in the distal direction,
It is preferable that the base end portion of the tip electrode expands in diameter from the tip of the tip reduced diameter portion, which is the tip of the catheter shaft, toward the tip.

According to the electrode catheter having such a configuration, the diameter of the tip reduced diameter portion is reduced in the distal direction, and the diameter of the proximal end portion of the tip electrode is expanded in the distal direction. A constriction is formed by the part.
This ensures that the boundary between the tip electrode and the catheter shaft does not come into contact with body tissue during ablation treatment, thereby preventing abnormal temperature rise around the boundary. be able to.

(3) In the electrode catheter of the present invention, it is preferable that the distal end portion of the distal end electrode has a partially spherical shape with a diameter equal to the maximum outer diameter of the proximal end portion.

(4) In the longitudinal cross-sectional view of the electrode catheter of (2) or (3) above, the angle (α) formed by the tapered distal end portion and the proximal portion of the distal electrode is 160° or less. preferable.
As a result, it is possible to more reliably avoid the interface between the tip electrode and the catheter shaft from coming into contact with body tissue during the ablation treatment.

(5) In the electrode catheter of the present invention, the value of (t)/(D ₃₀ ) is 0.12 to 0, where (D ₃₀ ) is the maximum outer diameter of the tip electrode and (t) is the wall thickness. .25 is preferred.

According to the electrode catheter of the present invention, during ablation treatment, it is possible to prevent abnormal temperature rise around the boundary between the tip electrode and the catheter shaft, and to prevent the tip portion and the large outer diameter portion from The entire surface of the tip electrode, including, can be evenly irrigated from the inside.

1 is a front view of an ablation catheter according to one embodiment of the invention; FIG. FIG. 2 is a detailed view of part II of FIG. 1; FIG. 2 is a cross-sectional view taken along line III-III in FIG. 1; FIG. 4 is a sectional view along IV-IV of FIGS. 2 and 3;

<Embodiment>
Hereinafter, an ablation catheter according to one embodiment of the electrode catheter of the present invention will be described with reference to the drawings. This ablation catheter is used to treat arrhythmia in the heart.

The ablation catheter 100 of this embodiment shown in FIGS. 1 to 4 has a distal flexible portion 102, and a catheter shaft 10 formed with eight lumens 11L to

18L including lumens

11L and 12L serving as fluid flow paths. , a tip electrode 30 made of a conductive porous material connected to the tip side of the catheter shaft 10, three ring-shaped electrodes 41 to 43 attached to the tip flexible portion 102 of the catheter shaft 10, and the catheter shaft 10 is inserted through the interior of the catheter shaft 10 (

lumens

15L and 17L) to flex the distal flexible portion 102 of 10 in a first direction (the direction indicated by arrow A in FIG. 2), and its distal end is connected to the anchor member 20. In order to bend the first operation wire 21 which is fixed and whose proximal end can be pulled and the distal flexible portion 102 of the catheter shaft 10 in the second direction (the direction indicated by the arrow B in FIG. 2), A second operation wire 22 which is inserted through the inside of the catheter shaft 10 (

lumens

16L and 18L), whose distal end is connected and fixed to the anchor member 20, and whose proximal end can be pulled and operated, and the lumen 11L of the catheter shaft 10. and 12L, a leaf spring 60 for oscillation arranged inside the tip flexible portion 102 along the axial direction of the catheter shaft 10, and a base of the catheter shaft 10. Equipped with an end-mounted control handle 70 and an irrigation liquid injection tube 80, the catheter shaft 10 has a distally tapered portion 101 with a distally tapered diameter, and the tip electrode 30 is located at the distal end. A base end portion 32 that expands in diameter from the tip position of the diameter-reduced portion 101 toward the tip, and a hemispherical tip portion 31 that is continuous with the base end portion 32 and has a diameter equal to the maximum outer diameter (D ₃₀ ) of the base end portion 32. The tip electrode 30 is a hollow structure with an internal space 36 communicating with the

lumens

11L and 12L of the catheter shaft 10, and the wall thickness of the tip electrode 30 surrounding this internal space 36 is equal to the proximal end. It is substantially uniform throughout portion 32 and tip portion 31 .

The ablation catheter 100 includes a catheter shaft 10, a tip electrode 30, ring electrodes 41 to 43, a first operation wire 21, a second operation wire 22, flow

channel forming tubes

51 and 52, and a plate. It comprises a spring 60, a control handle 70 and an injection tube 80 for irrigation fluid.

A catheter shaft 10 that constitutes an ablation catheter 100 has a distal flexible portion 102 .
Here, the "flexible tip portion" refers to a portion of the catheter shaft that can be flexed (bent) by pulling the proximal end of the operation wire (first operation wire 21 or second operation wire 22). Refers to the tip.

The length (L ₁₀ ) of the catheter shaft 10 is usually 600-1500 mm, preferably 900-1200 mm, and a preferred example is 1100 mm.
The length of the tip flexible portion 102 is generally 25-100 mm, preferably 45-80 mm, and a preferred example is 60 mm.
The outer diameter (D ₁₀ ) of the catheter shaft 10 is usually 1.0-3.0 mm, preferably 1.6-3.0 mm, and a preferred example is 2.75 mm.

The catheter shaft 10 has a tip reduced-diameter portion 101 on the tip side of the tip flexible portion 102, the diameter of which is reduced in the tip direction.
The length (L ₁₀₁ ) of the reduced diameter portion 101 is usually 1.0 to 5.0 mm, preferably 1.0 to 3.0 mm, and a preferred example is 1.2 mm.
The outer diameter (D ₁₀₁ ) at the tip of the tip reduced diameter portion 101 is usually 1.5 to 3.0 mm, preferably 1.6 to 3.0 mm, and a preferred example is 2.75 mm.
The diameter reduction ratio (D ₁₀₁ /D ₁₀ ) of the tip reduced diameter portion 101 is usually 0.5 to 0.9, preferably 0.6 to 0.8, and a preferred example is 0.73. be.
The value of (D ₁₀ -D ₁₀₁ )/L ₁₀₁ is usually 0.2 to 0.9, preferably 0.5 to 0.8, and a preferred example is 0.63.

Catheter shaft 10 (excluding tip reduced diameter portion 101) is a multi-lumen structure.
As shown in FIG. 3, the catheter shaft 10 has an inner (core) portion 107 formed by fixing lumen tubes defining lumens 11L to 18L with a binder resin, and an inner portion 107 via a reinforcing braid layer 108. and an outer (shell) portion 109 made of a covering resin.

The hardness of the binder resin forming the inner portion 107 is, for example, 40D or less, preferably 25D to 35D. Examples of the resin material forming the inner portion 107 include nylon resin, polyether block polyamide resin, polyurethane resin, and polyolefin resin.

A lumen tube forming the lumens 11L to 18L is made of resin.
As the resin constituting the lumen tube, for example, fluorine resin, nylon resin such as nylon 11/nylon 12, polyurethane resin, polyolefin resin, etc. can be used. It is preferable to use a fluororesin from the viewpoint of excellent mobility of a member inserted therein.
Specifically, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-ethylene copolymer (ETFE) and the like can be exemplified.

The outer portion 109 of the catheter shaft 10 is made of a resin material covering the inner portion 107 .
The hardness of the resin forming the outer portion 109 is, for example, 72D or less, preferably 35D to 72D.
It is preferable that the hardness of the outer portion 109 increases stepwise in the proximal direction.
As the resin material forming the outer portion 109, a thermoplastic polyamide-based elastomer can be mentioned, and a polyether block amide copolymer is preferable.

Lumens

11L and 12L of catheter shaft 10 are lumens that form flow paths for irrigation fluids. Here, physiological saline can be exemplified as the "liquid".
As shown in FIG. 3, a channel-forming tube 51 is inserted through the lumen 11L, and a channel-forming tube 52 is inserted through the lumen 12L.

An irrigation liquid is circulated inside the flow

path forming tubes

51 and 52 . By circulating the liquid inside the flow

path forming tubes

51 and 52, the sealing performance of the irrigation liquid (the effect of preventing the liquid from leaking out from the lumen) can be improved.
As materials for forming the flow

path forming tubes

51 and 52, resin materials such as polyimide, polyetheretherketone (PEEK), and nylon 11, and metal materials such as stainless steel and Ni—Ti superelastic alloys can be used. can.

Lumens

13L and 14L of the catheter shaft 10 are lumens through which lead wires or the like are inserted.
As shown in FIG. 3, the lead wire 35 of the tip electrode 30 and the thermocouple 90 are passed through the lumen 13L, and the lead wires 46-48 of the ring electrodes 41-43 are passed through the lumen 14L.

The lumens 15L to 18L of the catheter shaft 10 are passages for manipulating wires for deflecting the tip of the catheter shaft 10 by deflecting the tip flexible portion 102 .
As shown in FIG. 3, a first operation wire 21 is inserted through the lumen 15L to bend the tip flexible portion 102 of the catheter shaft 10 in the first direction indicated by the arrow A in FIG.
The first operation wire 21 is inserted through the inside of the catheter shaft 10 (the lumen 15L at the distal flexible portion 102 and the lumen 17L at the proximal end portion of the shaft) so as to be axially movable.
The tip of the first operation wire 21 is connected and fixed to the anchor member 20 arranged inside the tip flexible portion 102 . The proximal end of the first operation wire 21 is connected to the knob 75 of the control handle 70 so that it can be pulled.

As shown in FIG. 3, a second operation wire 22 is inserted through the lumen 16L to bend the tip flexible portion 102 of the catheter shaft 10 in the second direction indicated by the arrow B in FIG.
The second operation wire 22 is axially movably inserted inside the catheter shaft 10 (the lumen 16L at the distal flexible portion 102 and the lumen 18L at the proximal end portion of the shaft).
The tip of the second operation wire 22 is connected and fixed to the anchor member 20 so as to face the tip of the first operation wire 21 across the central axis of the catheter shaft 10 . The proximal end of the second operation wire 22 is connected to the knob 75 of the control handle 70 so that it can be pulled.

As shown in FIG. 3, a leaf spring 60 extending in the axial direction of the catheter shaft 10 is arranged inside the distal flexible portion 102 . By arranging the leaf spring 60 , the tip flexible portion 102 is easily bent in a direction (first direction or second direction) perpendicular to the plane of the leaf spring 60 .

A control handle 70 is attached to the proximal end of the catheter shaft 10 . A connector (not shown) having a plurality of terminals is provided in the control handle 70. The terminals of the connector have lead wires (not shown in FIG. 3) connected to the tip electrode 30 and the ring electrodes 41 to 43, respectively. The proximal ends of the indicated leads 35 and 46-48) are connected, respectively.
The control handle 70 also has a knob 75 for pulling the proximal end of the first operating wire 21 and the proximal end of the second operating wire 22 when bending the distal flexible portion 102 of the catheter shaft 10 . is attached.

The injection tube 80 shown in FIG. 1 is connected to the catheter shaft 10 through the inside of the control handle 70. The injection tube 80 passes through the inside of the catheter shaft 10 (the flow path inserted through the lumen 11L). An irrigation liquid is supplied to the inside of the forming tube 51 and the passage forming tube 52 inserted through the lumen 12L.

A tip electrode 30 is connected to the tip side of the catheter shaft 10 .
The tip electrode 30 that constitutes the ablation catheter 100 has a small-diameter cylindrical portion 33 inserted inside the catheter shaft 10 (tip reduced diameter portion 101) and a diameter that expands in the distal direction from the tip position of the tip reduced diameter portion 101. It consists of a base end portion 32 and a hemispherical tip portion 31 that is continuous with the base end portion 32 and has a diameter equal to the maximum outer diameter (D ₃₀ ) of the base end portion 32 .

As shown in FIGS. 2 and 4, proximal portion 32 and distal portion 31 appear as the outer appearance of tip electrode 30, while cylindrical portion 33 is inserted inside catheter shaft 10 so that the distal portion of tip electrode 30 is not deformed. It doesn't show up in appearance.

As shown in FIG. 2, the tip diameter reduction portion 101 of the catheter shaft 10 that is reduced in diameter in the distal direction and the proximal end portion 32 of the tip electrode 30 that is expanded in the distal direction provide a connection between the catheter shaft 10 and the tip electrode 30. A constriction having a minimum outer diameter equal to the outer diameter of the connecting portion (boundary) is formed.
As a result, it is possible to prevent the connecting portion between the catheter shaft 10 and the tip electrode 30 from coming into contact with body tissue during cauterization treatment, and as a result, abnormal temperature rise around the connecting portion can be prevented. can be prevented.

As shown in FIG. 4, the tip electrode 30 has an internal space 36 that communicates with the

lumens

11L and 12L of the catheter shaft 10 and stores liquid.

The tip electrode 30 is made of a conductive porous material.
Specific examples of the porous material forming the tip electrode 30 include stainless steel, tungsten, titanium, aluminum, platinum, copper, and gold.

The irrigation liquid can permeate the porous material. Therefore, the liquid supplied to the internal space 36 by flowing through the

lumens

11L and 12L (channel forming tubes 51 and 52) of the catheter shaft 10 moves (permeates) through the wall of the tip electrode 30 surrounding the internal space 36. ) and ooze to the surface of the tip electrode 30, thereby irrigating the tip electrode 30 from the inside.

A tip electrode constructed of a porous material can also be internally irrigated without creating an internal space.
However, in the ablation catheter 100 of this embodiment, the interior space 36 is formed in the tip electrode 30 . Moreover, the wall thickness (t) of the tip electrode 30 surrounding this internal space 36 is uniform throughout the proximal portion 32 and the distal portion 31 .

As a result, even the surface of the tip portion 31, which has a long distance (axial distance) from the catheter shaft 10 and a long distance (radial distance) from the central axis of the tip electrode 30, can be coated with the liquid in a short time. It can be reached and adequately irrigated. In addition, the wall thickness (t) of tip electrode 30 is uniform across proximal portion 32 and distal portion 31, thereby irrigating the entire surface of tip electrode 30 (proximal portion 32 and distal portion 31) evenly. can do.

The maximum outer diameter (D ₃₀ ) of the tip electrode 30 at the tip of the proximal portion 32 (the diameter of the hemisphere that is the shape of the tip portion 31 ) is approximately the same as the outer diameter (D ₁₀ ) of the catheter shaft 10 .
The outer diameter (D ₃₂ ) at the proximal end of the proximal portion 32 is the same as the outer diameter (D ₁₀₁ ) at the distal end of the distal reduced diameter portion 101 .
The length (L ₃₂ ) of the base end portion 32 is usually 2.0 to 4.0 mm, preferably 2.0 to 3.0 mm, preferably 2.7 mm.
The diameter expansion ratio (D ₃₀ /D ₃₂ ) of the base end portion 32 is usually 1.1 to 2.0, preferably 1.2 to 1.7, and a preferred example is 1.38. be.
The value of (D ₃₀ -D ₃₂ )/L ₃₂ is usually 0.1 to 1.0, preferably 0.2 to 0.5, and a preferred example is 0.28.
The outer diameter of the cylindrical portion 33 is a size that can be inserted into the tip reduced diameter portion 101, and is usually 0.5 to 4.0 mm, preferably 0.7 to 3.0 mm. If shown, it is 1.5 mm.

In a longitudinal cross-sectional view of the ablation catheter 100 as shown in FIG. 4, the angle (α) formed by the reduced-diameter tip portion 101 and the base end portion 32 of the tip electrode 30 is preferably 160° or less, more preferably. is 90-130°.

When this angle (α) is 160° or less, a conspicuous constriction is formed by the tip reduced diameter portion 101 and the proximal end portion 32, and during cauterization treatment, the connecting portion between the catheter shaft 10 and the tip electrode 30 becomes difficult. Contact with body tissue can be reliably avoided.
When the distal reduced diameter portion 101 and/or the proximal end portion 32 are curved surfaces (R are applied), the proximal end of the distal reduced diameter portion 101 and the connection portion can be seen in a longitudinal cross-sectional view of the ablation catheter 100. and the straight line connecting the tip of the base end portion 32 and the connecting portion is defined as (α).

In the ablation catheter 100 of this embodiment, the ratio [(t)/(D ₃₀ )] of the wall thickness (t) to the maximum outer diameter (D ₃₀ ) of the tip electrode 30 is 0.12 to 0.25. is preferred, and more preferably 0.18 to 0.22.
If the value of the ratio [(t)/(D ₃₀ )] is too small (thin), sufficient strength as the tip electrode cannot be ensured.
On the other hand, if this value is too large (thick), it may take a long time for the liquid in the internal space to reach the electrode surface, and the electrode surface may not be sufficiently irrigated.

Ring-shaped electrodes 41 to 43 are attached to the tip flexible portion 102 of the catheter shaft 10 . The method for fixing the tip electrode 30 and the ring-shaped electrodes 41 to 43 is not particularly limited, and examples thereof include a method such as adhesion.
The ring-shaped electrodes 41 to 43 are made of metal with good electrical conductivity, such as aluminum, copper, stainless steel, gold, and platinum. It should be noted that it is preferably made of platinum or the like in order to have good X-ray imaging properties.
The outer diameter of the ring-shaped electrodes 41 to 43 is not particularly limited, but is preferably approximately the same as the outer diameter of the catheter shaft 10 .

As shown in FIGS. 3 and 4, a thermocouple 90 for controlling the ablation temperature is placed (inserted) in the inner space 36 of the tip electrode 30 and the lumen 13L of the catheter shaft 10. A measuring junction 95 of thermocouple 90 is located in the tip wall of tip electrode 30 .

According to the ablation catheter 100 of the present embodiment, the distal end portion 101 whose diameter is reduced in the distal direction and the proximal end portion 32 whose diameter is expanded in the distal direction form the outside of the connecting portion between the catheter shaft 10 and the tip electrode 30. Since a constriction with a diameter as the minimum outer diameter is formed, it is possible to avoid contact of the connecting portion between the catheter shaft 10 and the tip electrode 30 with body tissue during ablation treatment. Abnormal temperature rise can be prevented.

In addition, the inner space 36 is formed in the tip electrode 30 as a liquid storage space, and the wall thickness (t) of the tip electrode 30 surrounding the inner space 36 is uniform throughout the proximal portion 32 and the distal portion 31. , the entire surface of the tip electrode 30 (proximal portion 32 and distal portion 31) can be rapidly and evenly irrigated from within.

REFERENCE SIGNS LIST 100 ablation catheter 10 catheter shaft 101 tip reduced diameter portion 102 tip

flexible portion

11L, 12L lumen (liquid flow path)
13L, 14L lumen (passage for lead wire)
15L to 18L lumen (passage for pulling wire)
107 inner portion 108 reinforcing braid layer 109 outer portion 20 anchor member 21 first operation wire 22 second operation wire 30 tip electrode 31 tip portion of tip electrode 32 base portion of tip electrode 33 cylindrical portion of tip electrode 35 tip Electrode lead wire 36 Internal space of tip electrode 41-43 Ring-shaped electrode 46-48 Ring-shaped

electrode lead wire

51, 52 Channel forming tube 60 Leaf spring 70 Control handle 75 Knob 80 Liquid injection tube 90 Thermocouple 95 Temperature measuring junction

Claims

comprising a catheter shaft having a lumen serving as a liquid flow path, and a tip electrode made of a porous material connected to the tip side of the catheter shaft,
The tip electrode has a proximal portion whose diameter increases in the distal direction from the distal end of the catheter shaft, and a distal portion which continues to the proximal portion and decreases in diameter in the distal direction. A hollow structure in which a communicating internal space is formed,
An electrode catheter, wherein a wall thickness of said tip electrode surrounding said interior space is substantially uniform throughout said proximal portion and said distal portion.
The catheter shaft has a tip-reduced-diameter portion whose diameter is reduced in the distal direction,
2. The electrode catheter according to claim 1, wherein the proximal portion of the tip electrode increases in diameter from the tip of the tip reduced diameter portion in the distal direction.
The electrode catheter according to claim 1 or 2, wherein the tip portion of the tip electrode has a partially spherical shape with a diameter equal to the maximum outer diameter of the base end portion.
4. The electrode catheter according to claim 2 or 3, wherein an angle (α) formed by the reduced diameter tip portion and the base end portion of the tip electrode is 160° or less in a longitudinal cross-sectional view of the electrode catheter. electrode catheter.
Where the maximum outer diameter of the tip electrode is (D 30 ) and the wall thickness is (t), the value of (t)/(D 30 ) is 0.12 to 0.25. Item 5. The electrode catheter according to any one of items 1 to 4.