Electrode catheter

Abstract

To provide an electrode catheter capable of suppressing twisting and vibration of a conductor wire and reducing noise of a signal transmitted by the conductor wire.SOLUTION: An electrode catheter has: an outer shaft 10; an inner shaft 20 extending into a lumen of the outer shaft 10; one or more electrodes 50 arranged in a distal part of the outer shaft 10; a first cylindrical member 30 which is arranged in the lumen of the outer shaft 10 and outside the inner shaft 20 and is positioned nearer on a proximal side than the proximal end of an electrode 50 of the one or more electrodes 50 that is arranged nearest on the proximal side; and a conductor wire 40 which is connected to the electrode 50 and extends outside the inner shaft 20 and in the lumen of the first cylindrical member 30. In a cross section vertical to a longitudinal axis direction x, a length after subtracting a length between two points where a straight-line B crosses an outer wall of the inner shaft 20 from a length between two points where the straight-line B passing a figure center C of the inner shaft 20 crosses a lumen wall of the first cylindrical member 30 is not more than three times as long as a long diameter of the conductor wire 40.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an electrode catheter used for measuring the potential of internal organs, mainly the heart, and for cauterizing internal tissues.

Background Art

[0002] In the examination and treatment of arrhythmias such as atrial fibrillation, a catheter having electrodes may be used. During the examination, the electrode catheter is inserted into the heart cavity to measure the intracardiac potential and identify the abnormal site of the heart that causes the arrhythmia. During the treatment, an ablation operation is performed in which a high-frequency current is passed from the electrodes of the catheter to the myocardium that causes the arrhythmia, and the origin of the arrhythmia is cauterized to electrically isolate it from the heart. Further, when atrial fibrillation occurs during these examinations or treatments, it becomes difficult to measure and analyze the potential in the heart, which hinders the examination and treatment. Therefore, defibrillation is performed by applying an electrical stimulus from the electrodes of the catheter to the heart.

[0003] For example, Patent Documents 1 to 4 disclose a deflectable catheter in which a lead wire connected to an electrode is disposed in a central lumen of a catheter tube whose inner surface of the outer wall is lined with a reinforcing tube.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0005] In an electrode catheter, signals from or to the electrodes are transmitted through conducting wires. At this time, in a conventional electrode catheter as described above, during operations of the electrode catheter such as when delivering the electrode catheter to a lesion site or when bending the distal portion of the catheter, the conducting wires may be twisted or vibrated within the lumen of the catheter, resulting in noise in the signals transmitted by the conducting wires and a decrease in the signal-to-noise ratio. Therefore, an object of the present invention is to provide an electrode catheter capable of suppressing the twisting and vibration of the conducting wires and reducing the noise of the signals transmitted by the conducting wires.

Means for Solving the Problems

[0006] One embodiment of the electrode catheter of the present invention that can solve the above problems includes an outer shaft having a distal end and a proximal end in the longitudinal axis direction and having a lumen extending in the longitudinal axis direction, an inner shaft extending in the lumen of the outer shaft, one or more electrodes disposed at the distal portion of the outer shaft, and a first cylindrical member having a distal end and a proximal end in the longitudinal axis direction and having a lumen extending in the longitudinal axis direction. The first cylindrical member is disposed outside the lumen of the outer shaft and outside the inner shaft such that the inner shaft is disposed within the lumen of the first cylindrical member, and the distal end of the first cylindrical member is located proximal to the proximal end of the most proximal electrode among the one or more electrodes. The first cylindrical member has a conducting wire connected to the electrode and extending in the lumen of the outer shaft outside the inner shaft and within the lumen of the first cylindrical member. In a cross-section perpendicular to the longitudinal axis direction, the length obtained by subtracting the length between two points where the straight line passing through the centroid of the inner shaft intersects the inner wall of the lumen of the first cylindrical member from the length between two points where the straight line intersects the outer wall of the inner shaft is not more than three times the major diameter of the conducting wire. With such a configuration, the twisting and vibration of the conducting wire within the lumen of the catheter can be suppressed, and thus the noise of the signals transmitted from or to the electrodes through the conducting wire can be reduced.

[0007] In the longitudinal axis direction, it is preferable that the length of the first cylindrical member is 50% or more of the length from the proximal end of the most proximal electrode to the proximal end of the outer shaft.

[0008] In the longitudinal axis direction, the length from the proximal end of the electrode disposed closest proximally to the distal end of the first cylindrical member is preferably not more than five times the length from the distal end of the outer shaft to the proximal end of the electrode disposed closest proximally.

[0009] The electrode catheter according to an embodiment of the present invention further has a second cylindrical member disposed outside the inner shaft, and it is preferable that the distal end of the first cylindrical member is located more proximally than the distal end of the second cylindrical member.

[0010] The electrode catheter according to an embodiment of the present invention further has a second cylindrical member disposed outside the inner shaft, and it is preferable that the distal end of the first cylindrical member is located more proximally than the proximal end of the second cylindrical member. In this case, in a cross section perpendicular to the longitudinal axis direction of the section where the second cylindrical member is disposed in the longitudinal axis direction, the length obtained by subtracting the length between two points where the straight line passing through the centroid of the inner shaft intersects the inner wall of the lumen of the outer shaft from the length between two points where the straight line intersects the outer wall of the second cylindrical member is preferably not more than three times the major diameter of the conducting wire. Further in this case, in the longitudinal axis direction, the length from the proximal end of the second cylindrical member to the distal end of the first cylindrical member is preferably not more than two times the length from the distal end of the outer shaft to the proximal end of the electrode disposed closest proximally.

[0011] In the longitudinal axis direction, when the length from the distal end of the outer shaft to the distal end of the first cylindrical member is d, the outer shaft and the first cylindrical member are not fixed on the distal side of a point D which is d closer to the proximal side than the distal end of the first cylindrical member, and it is preferable that the electrode catheter according to an embodiment of the present invention has a fixing portion where the outer shaft and the first cylindrical member are fixed on the proximal side of the point D of the first cylindrical member.

[0012] It is preferable that the first cylindrical member is not fixed to the inner shaft.

[0013] It is preferable that the first cylindrical member extends to a position more proximal than the proximal end of the outer shaft.

[0014] The first cylindrical member is preferably composed of at least one polymer or elastomer selected from the group consisting of polyolefin resins, polyamide resins, polyimide resins, polyester resins, polyurethane resins, vinyl chloride resins, silicone resins, polycarbonate resins, and aromatic polyether ketone resins.

Advantages of the Invention

[0015] The electrode catheter of the present invention can suppress the kinking and vibration of the conducting wire in the lumen of the catheter, so that the noise of the signal transmitted from or to the electrode through the conducting wire can be reduced. Thereby, the S / N ratio of the signal transmitted by the conducting wire can be improved.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Mode for Carrying Out the Invention

[0017] Hereinafter, the present invention will be described based on embodiments. However, the present invention is not limited by the following embodiments, and it is of course possible to appropriately modify and implement it within a range that conforms to the gist of the foregoing and following descriptions, and all of them are included in the technical scope of the present invention. In each drawing, for convenience, hatching, reference numerals of members, etc. may be omitted, but in such cases, reference shall be made to the specification and other drawings. Also, the dimensions of various members in the drawings may differ from the actual dimensions because priority is given to facilitating the understanding of the features of the present invention.

[0018] The electrode catheter according to an embodiment of the present invention includes an outer shaft having a distal end and a proximal end in the longitudinal axis direction and having a lumen extending in the longitudinal axis direction, an inner shaft extending in the lumen of the outer shaft, one or more electrodes disposed at the distal portion of the outer shaft, and a first cylindrical member having a distal end and a proximal end in the longitudinal axis direction and having a lumen extending in the longitudinal axis direction. The inner shaft is disposed inside the lumen of the outer shaft and outside the inner shaft such that the inner shaft is disposed within the lumen of the first cylindrical member, and the distal end of the first cylindrical member is located proximal to the proximal end of the most proximal electrode among the one or more electrodes. The first cylindrical member, a conductor connected to the electrodes and extending in the lumen of the outer shaft outside the inner shaft and within the lumen of the first cylindrical member. In a cross-section perpendicular to the longitudinal axis direction, the length obtained by subtracting the length between two points where the straight line passing through the centroid of the inner shaft intersects the outer wall of the inner shaft from the length between two points where the straight line passing through the centroid of the inner shaft intersects the inner wall of the first cylindrical member is not more than three times the major diameter of the conductor.

[0019] By having the above configuration, the electrode catheter according to the embodiment of the present invention can define an insertion passage for the conducting wire between the outer surface of the inner shaft and the inner cavity wall of the first cylindrical member. Since the defined insertion passage has a width equal to or less than a predetermined value, it is possible to suppress the kinking and vibration of the conducting wire, and reduce the noise of the signal transmitted from or to the electrode through the conducting wire. As a result, the S / N ratio of the signal transmitted by the conducting wire can be improved.

[0020] With reference to FIGS. 1 to 12, a configuration example of the electrode catheter will be described. FIG. 1 shows a plan view of an electrode catheter according to an embodiment of the present invention. FIG. 2 shows a longitudinal cross-sectional view of the II portion of the electrode catheter shown in FIG. 1, that is, an enlarged distal portion. In FIG. 2, although the two conducting wires may not necessarily be present on the same cross-section, they are shown on the same cross-section for convenience. FIG. 3 shows a cross-sectional view of the electrode catheter taken along line III-III of FIG. 2. FIGS. 4 and 5 show different modified examples of the cross-sectional view shown in FIG. 3. FIG. 6 shows a cross-sectional view of the electrode catheter taken along line VI-VI of FIG. 2. FIG. 7 shows a longitudinal cross-sectional view of the distal portion of an electrode catheter according to another embodiment of the present invention. FIG. 8 shows a cross-sectional view of the electrode catheter taken along line VIII-VIII of FIG. 7. FIG. 9 shows a longitudinal cross-sectional view of the distal portion of an electrode catheter according to still another embodiment of the present invention. FIG. 10 shows a cross-sectional view of the electrode catheter taken along line X-X of FIG. 9. FIG. 11 shows a cross-sectional view of the electrode catheter taken along line XI-XI of FIG. 2, and FIG. 12 shows a modified example of the cross-sectional view shown in FIG. 11. In this specification, the electrode catheter may be simply referred to as a catheter.

[0021] In the present invention, the proximal side refers to the direction on the user's hand side in the extending direction of the electrode catheter 1, and the distal side refers to the opposite direction to the proximal side, that is, the direction on the side of the subject to be treated. It is preferable that the extending direction of the electrode catheter 1 is the same as the longitudinal axis direction x of the outer shaft 10. In a cross-section perpendicular to the longitudinal axis direction x, the direction connecting the center of the outer shaft 10 and a point on the circumscribed circle of the outer shaft 10 is referred to as the radial direction y. In the figures in this specification, the left side of the figure is the distal side and the right side of the figure is the proximal side.

[0022] As shown in Fig. 1, the electrode catheter 1 has an outer shaft 10 that has a distal end and a proximal end in the longitudinal axis direction x and has a lumen extending in the longitudinal axis direction x. The outer shaft 10 has its distal end inserted into the body, and the distal end is delivered to the treatment site by operating a handle or the like connected to the proximal end side. For this reason, the outer shaft 10 is preferably flexible, and metals or resins can be used as the material. Since it is inserted into the body, the outer shaft 10 is preferably made of a biocompatible material.

[0023] As shown in Fig. 2, one or more electrodes 50 are arranged at the distal portion of the outer shaft 10. Also, although not shown, members for inspection and treatment other than the electrodes 50, such as sensors, may be arranged at the distal portion of the outer shaft 10. An internal structure for bending the distal portion of the catheter 1 may be arranged in the lumen of the outer shaft 10. Since the members as described above are arranged in the lumen of the outer shaft 10, it preferably has a cylindrical structure. The length, outer diameter, thickness, etc. of the outer shaft 10 in the longitudinal axis direction x can be appropriately selected according to the purpose of use.

[0024] Examples of the material constituting the outer shaft 10 include synthetic resins such as polyolefin resins such as polyethylene and polypropylene; polyamide resins such as nylon; polyester resins such as PET; polyimide resins; aromatic polyether ketone resins such as PEEK; polyether polyamide resins; polyurethane resins; fluorine resins such as PTFE, PFA, and ETFE; vinyl chloride resins; silicone resins; and natural rubbers.

[0025] Examples of the outer shaft 10 having a cylindrical structure include a hollow coil formed by winding one or more wire rods in a helical shape, a structure in which the inner surface and / or outer surface of the hollow coil or hollow body is coated with resin, a cylindrical resin tube, or a structure in which these are connected in the longitudinal axis direction x. The outer shaft 10 may have a single-layer structure or a multi-layer structure. Alternatively, a part of the outer shaft 10 in the longitudinal axis direction x or the circumferential direction may be composed of a single layer, and the other part may have a multi-layer structure. When the outer shaft 10 has a multi-layer structure, for example, as an intermediate layer of the resin tube constituting the outer shaft 10, a structure using a metal braid such as stainless steel, carbon steel, or nickel-titanium alloy can be adopted.

[0026] Preferably, a tip portion 11 is disposed at the distal end of the outer shaft 10. The tip portion 11 may be a member different from the outer shaft 10 or may be formed as a part of the same member. When the tip portion 11 is a member different from the outer shaft 10, the tip portion 11 may include a portion inserted into the inner cavity of the outer shaft 10 or a portion protruding distally from the distal end of the outer shaft 10. When the tip portion 11 is formed as a part of the outer shaft 10, the tip portion 11 may be formed by closing the opening at the distal end of the outer shaft 10 by heat-sealing or the like at the distal end of the outer shaft 10. The tip portion 11 may be a tip electrode.

[0027] Preferably, a handle 7 is disposed on the proximal side of the outer shaft 10, and the proximal end of the outer shaft 10 is preferably fixed inside the handle 7. Preferably, proximal ends of a conductor 40 and a wire 22, which will be described later and extend from the inner cavity of the outer shaft 10, are disposed inside the handle 7. The handle 7 may be provided with a wire operation portion 70 so as to facilitate operation of the wire 22. By fixing the proximal end of the wire 22 to the wire operation portion 70, the wire operation portion 70 can be operated to pull or release the wire 22, thereby curving or returning the distal portion of the catheter 1.

[0028] The electrode catheter 1 has an inner shaft 20 extending into the lumen of the outer shaft 10. The inner shaft 20 may have a solid structure or a hollow structure. Since the electrode catheter 1 has the inner shaft 20 in the lumen of the outer shaft 10, the rigidity of the outer shaft 10 can be increased, and the insertion of the catheter 1 into the blood vessel can be facilitated. Also, since the electrode catheter 1 has the inner shaft 20 in the lumen of the outer shaft 10, the force applied from the proximal side of the catheter 1 can be transmitted to the distal side, and the distal portion of the catheter 1 can be made into a deflectable catheter that curves.

[0029] When the inner shaft 20 has a hollow structure, the inner shaft 20 is preferably a tube, a pipe having a cylindrical structure, or a hollow coil formed by winding one or a plurality of wire rods in a spiral shape. Among these, the inner shaft 20 is preferably a coil or a pipe, or a combination thereof. If the inner shaft 20 has such a configuration, while increasing the rigidity of the outer shaft 10, appropriate flexibility can also be imparted, so that the catheter 1 can be easily inserted into the blood vessel, and the distal portion of the catheter 1 can be easily delivered to the lesion even in a bent blood vessel.

[0030] The outer diameter of the cross section perpendicular to the longitudinal axis direction x of the inner shaft 20 is not particularly limited, and may be a circular shape as shown in FIG. 3, an elliptical shape as shown in FIG. 4, or a shape combining these. When the inner shaft 20 has a hollow structure, the inner cavity shape of the cross section perpendicular to the longitudinal axis direction x of the inner shaft 20 may also be a circular shape, an elliptical shape, or a shape combining these, similar to the outer shape. When the inner shaft 20 has a hollow structure, as shown in FIG. 5, an elastic member 21 and a wire 22 described later may be arranged in the inner cavity of the inner shaft 20.

[0031] The inner shaft 20 may extend to the vicinity of the proximal end of the outer shaft 10. The inner shaft 20 may be composed of the same member over the longitudinal axis direction x, or may have a configuration in which different members are connected in the middle of the longitudinal axis direction x. The distal end of the inner shaft 20 may be located in the vicinity of the distal end of the outer shaft 10, or may be located proximal to the distal end of the outer shaft 10. When the distal end of the inner shaft 20 is located proximal to the distal end of the outer shaft 10, for example, the catheter 1 can be configured such that the distal end portion of the inner shaft 20 is the proximal end of the curvature and the portion distal to it is bendable.

[0032] As the material constituting the inner shaft 20, the same synthetic resin, metal, etc. as those of the outer shaft 10 can be used. The inner shaft 20 may have a single-layer structure, or may have a multi-layer structure similar to that of the outer shaft 10. The material of the inner shaft 20 may be the same as or different from the material of the outer shaft 10. The inner shaft 20 is preferably made of metal, and more preferably a coil formed by winding a stainless steel wire in a helical shape. Alternatively, the inner shaft 20 preferably has a configuration in which the proximal side is composed of a metal or resin tube and a metal coil is connected to the distal side of the tube. If the inner shaft 20 has such a configuration, it becomes easy to make the distal portion of the electrode catheter 1 deflectable while giving sufficient rigidity to the outer shaft 10.

[0033] As shown in FIG. 5 and FIGS. 9 and 10, which will be described later as other embodiments of the electrode catheter 1, a wire 22 extending in the longitudinal axis direction x may be disposed in the lumen of the inner shaft 20. The wire 22 may be one or a plurality of wires. By pulling the wire 22 proximally, the distal portion of the electrode catheter 1 can be curved. Alternatively, the distal portion of the electrode catheter 1 may be curved by pushing the wire 22 distally. The distal portion of the wire 22 is preferably connected or fixed to the distal portion of the electrode catheter 1, preferably to the distal portion of the elastic member 21, which will be described later, and the proximal portion of the wire 22 is preferably connected or fixed to the wire operation portion 70.

[0034] As the wire 22, for example, a metal wire such as stainless steel, carbon steel, or nickel-titanium alloy, or a wire formed of a synthetic resin such as a polyamide-based resin, a polyolefin-based resin, a polyester-based resin, an aromatic polyether ketone-based resin, a polyimide-based resin, or a fluorine-based resin can be used.

[0035] In order to adjust the degree of curvature of the distal portion of the electrode catheter 1, it is preferable that an elastic member 21 is provided. As shown in FIG. 5, the elastic member 21 may extend in the lumen of the inner shaft 20, or as shown in FIG. 9, which will be described later as another embodiment, the proximal end portion of the elastic member 21 may be connected to the distal end portion of the inner shaft 20. Examples of the elastic member 21 include a leaf spring and a coil spring. The distal end portion of the elastic member 21 is preferably fixed to the distal end portion of the outer shaft 10, preferably the tip portion 11. The connection method between the elastic member 21 and other members is not particularly limited, and examples thereof include soldering such as welding, welding, adhesion with an adhesive, and caulking. As the material constituting the elastic member 21, reference can be made to the description of the material constituting the wire 22.

[0036] One or more electrodes 50 are arranged at the distal portion of the outer shaft 10. As shown in FIG. 2, it is preferable that the electrode 50 is provided outside the side hole provided at the distal portion of the outer shaft 10 so as to penetrate the outside and the inside of the outer shaft 10. The electrode 50 functions as a measurement electrode or a reference electrode during potential measurement. The shape of the electrode 50 may be, for example, a ring shape, a C-shaped cross-section with a notch in the ring, or a coil shape formed by winding a wire. By caulking the electrode 50 to the outer shaft 10, the electrode 50 can be arranged on the outer shaft 10. Alternatively, the electrode 50 may be a flat plate electrode such as a rectangular shape or a square shape independently formed in an island shape when viewed from the outside of the outer shaft 10. At least one of the inner surface and the outer surface of such a flat plate electrode may be a curved surface so as to easily follow the curved surface of the surface of the outer shaft 10. Among them, it is preferable that the electrode 50 is in a ring shape. Since the electrode 50 is in a ring shape, the area of the electrode 50 on the outer peripheral surface of the outer shaft 10 can be increased, and the electrode 50 can be easily brought into contact with the inner wall of the heart or the like.

[0037] The electrode 50 only needs to have conductivity and can be composed of a metal or a mixture containing a resin and a metal. Among them, as the material of the electrode 50, it is preferable to use a metal such as platinum, a platinum-iridium alloy, stainless steel, tungsten, or a conductive resin. When the electrode 50 is composed of a conductive resin, it is preferable to mix a contrast agent such as barium sulfate or bismuth oxide in order to be visible under fluoroscopy.

[0038] As shown in FIGS. 2 to 5, the electrode catheter 1 is a first cylindrical member 30 having a distal end and a proximal end in the longitudinal axis direction x and having a lumen extending in the longitudinal axis direction x. The inner shaft 20 is arranged inside the lumen of the first cylindrical member 30 and is arranged outside the lumen of the outer shaft 10 and outside the inner shaft 20. The distal end of the first cylindrical member 30 is located proximal to the proximal end of the electrode 50 arranged closest to the proximal side among one or more electrodes 50.

[0039] The first cylindrical member 30 is preferably made of an insulating material. The first cylindrical member 30 is preferably composed of at least one polymer or elastomer selected from the group consisting of, for example, polyolefin resins, polyamide resins, polyimide resins, polyester resins, polyurethane resins, vinyl chloride resins, silicone resins, polycarbonate resins, and aromatic polyether ketone resins. Among them, the first cylindrical member 30 is preferably composed of a polyolefin resin such as polyethylene. Thereby, the flexibility of the first cylindrical member 30 can be improved, and it becomes possible to flexibly define the insertion passage 35 for the conductor 40 described later by the first cylindrical member 30. In addition, the slidability of the conductor 40 with respect to the first cylindrical member 30 is improved, and damage to the conductor 40 due to contact between the conductor 40 and the first cylindrical member 30 during the manufacture or use of the electrode catheter 1 can be prevented.

[0040] A conductor 40 is connected to the electrode 50, and the conductor 40 extends through a side hole provided in the outer shaft 10 and in the inner cavity of the outer shaft 10, outside the inner shaft 20 and inside the first cylindrical member 30. The conductor 40 electrically connects the electrode 50 and an external device of the catheter 1, such as an electrocardiograph. The conductor 40 is electrically connected to the electrode 50. For example, when two electrodes 50 are arranged in the longitudinal axis direction x as shown in FIG. 2, it is preferable that one conductor 40 is connected to each electrode 50. Although not shown, three or more electrodes 50 may be arranged, and conductors 40 corresponding to the number of electrodes 50 may be further arranged.

[0041] The conductor 40 only needs to have conductivity. For example, copper wire, iron wire, stainless steel wire, piano wire, tungsten wire, nickel-titanium wire, etc. can be used. Among them, stainless steel wire is particularly preferable in that it is easy to pass the conductor 40 through the side hole of the outer shaft 10 due to its straightness and rigidity, and it is difficult for the connection part between the conductor 40 and the electrode 50 to break.

[0042] The single conducting wire 40 may be a single wire or a stranded wire. The shape of the cross-section perpendicular to the longitudinal axis direction x of the single conducting wire 40 can be, for example, circular, oval, polygonal, or a combination of these shapes. Whether the single conducting wire 40 is a single wire or a stranded wire, and regardless of the cross-sectional shape, the major diameter of the conducting wire 40 means the diameter of the circumscribed circle of the single conducting wire 40 in the cross-section perpendicular to the longitudinal axis direction x. The major diameter of the conducting wire 40 is not particularly limited. For example, the major diameter of the conducting wire 40 is preferably 0.05 mm or more, more preferably 0.08 mm or more, and even more preferably 0.1 mm or more. Also, for example, the major diameter of the conducting wire 40 is preferably 0.3 mm or less, more preferably 0.2 mm or less, and even more preferably 0.15 mm or less.

[0043] The conducting wire 40 may have a coating material on portions other than both ends connected to the electrode 50 or the like. Thereby, a short circuit with an adjacent member can be prevented. As the material of the coating material of the conducting wire 40, reference can be made to the description of the resin material constituting the outer shaft 10.

[0044] The electrode 50 and the conducting wire 40 can be connected by methods such as laser welding, resistance welding, and adhesion with an adhesive.

[0045] As shown in FIGS. 3 to 5, in the cross-section perpendicular to the longitudinal axis direction x, the length L obtained by subtracting the length L2 between the two points where the straight line B passing through the centroid C of the inner shaft 20 intersects the outer wall of the inner shaft 20 from the length L1 between the two points where the straight line B passing through the centroid C of the inner shaft 20 intersects the inner cavity wall of the first cylindrical member 30 1-2 is not more than three times the major diameter of the conducting wire 40. The length L 1-2 is preferably not more than 2.5 times the major diameter of the conducting wire 40, more preferably not more than 2.2 times, and may be not more than 2.1 times. With such a configuration, the insertion passage 35 for the conducting wire 40 can be defined by the outer surface of the inner shaft 20 and the inner cavity wall of the first cylindrical member 30. Since the defined insertion passage 35 has a width not exceeding a predetermined value, the twisting and vibration of the conducting wire 40 can be suppressed, and the noise of the signal transmitted from or to the electrode 50 through the conducting wire 40 can be reduced. Thereby, the S / N ratio of the signal transmitted by the conducting wire 40 can be improved. The length L 1-2If the upper limit is within the above range, for example, as shown in FIGS. 3 and 5, when the electrode catheter 1 has two conductive wires 40, the two conductive wires 40 can be arranged at positions shifted by, for example, 180° in the circumferential direction of the inner shaft 20, and it is possible to prevent these conductive wires 40 from being twisted or vibrating in the radial direction y in the insertion passage 35. Further, even when the electrode catheter 1 has three or more conductive wires 40, by arranging these three or more conductive wires 40 at intervals in the circumferential direction of the inner shaft 20, the conductive wires 40 can be arranged in the insertion passage 35 defined to have a width of a predetermined value or less, and it is possible to prevent the plurality of conductive wires 40 from being twisted or vibrating in the radial direction y in the insertion passage 35.

[0046] Also, the length L 1-2 may be equal to or less than 2 times, 1.5 times, or 1.2 times the major diameter of the conductive wire 40. If the upper limit of the length L 1-2 is within the above range, for example, as shown in FIG. 4, when the electrode catheter 1 has one conductive wire 40, the width of the insertion passage 35 for the conductive wire 40 can be made to be a predetermined value or less, and it is possible to prevent the conductive wire 40 from being twisted or vibrating in the radial direction y in the insertion passage 35. Further, even when the electrode catheter 1 has two or more conductive wires 40, by arranging these plurality of conductive wires 40 biased to a part of the circumferential direction of the inner shaft 20, the plurality of conductive wires 40 can be arranged in the insertion passage 35 defined to have a width of a predetermined value or less, and it is possible to prevent the conductive wires 40 from being twisted or vibrating in the radial direction y in the insertion passage 35. In this case, for example, the plurality of conductive wires 40 may be arranged with a 15° shift, a 20° shift, or a 30° shift in the circumferential direction of the inner shaft 20.

[0047] The length L 1-2 is preferably equal to or greater than 1 times the conductive wire 40, and more preferably 1.1 times or more. If the lower limit of the length L 1-2 is within the above range, the conductive wire 40 can be easily inserted into the insertion passage 35.

[0048] Here, the centroid C of the inner shaft 20 is the centroid of the outer edge shape of the inner shaft 20 in a cross-section perpendicular to the longitudinal axis direction x. Therefore, as shown in FIGS. 3 and 4, even when the inner shaft 20 has a solid structure, or as shown in FIG. 5, even when the inner shaft 20 has a hollow structure, the centroid C can be determined in the same manner.

[0049] Further, as shown in FIG. 4, in a cross-section perpendicular to the longitudinal axis direction x, when at least one of the outer surface of the inner shaft 20 and the inner cavity wall of the first cylindrical member 30 has a shape deviating from a perfect circle, the length L 1-2 is not uniquely determined. In this case, it is preferable that the length L 1-2 has the above range when the straight line B is drawn so as to be maximum. 1-2

[0050] The thickness of the first cylindrical member 30 in the radial direction y is preferably thinner than the thickness of the outer shaft 10. Thereby, since the flexibility of the first cylindrical member 30 can be ensured, even when the insertion passage 35 of the lead wire 40 also curves following it when the electrode catheter 1 is conveyed in a bent blood vessel, etc., the first cylindrical member 30 can also easily follow the curve, and it becomes easier to define the insertion passage 35 of the lead wire 40 arranged outside the inner shaft 20 by the first cylindrical member 30. Also, since the flexibility of the first cylindrical member 30 can be ensured, damage to the lead wire 40 can be prevented.

[0051] The bending strength of the first cylindrical member 30 is preferably smaller than the bending strength of the outer shaft 10. Thereby, since the flexibility of the first cylindrical member 30 can be ensured, even when the insertion passage 35 of the lead wire 40 also curves following it when the electrode catheter 1 is conveyed in a bent blood vessel, etc., the first cylindrical member 30 can also easily follow the curve, and it becomes easier to define the insertion passage 35 of the lead wire 40 arranged outside the inner shaft 20 by the first cylindrical member 30. Also, since the flexibility of the first cylindrical member 30 can be ensured, damage to the lead wire 40 can be prevented.

[0052] In the insertion passage 35 of the conducting wire 40 defined by the outer surface of the inner shaft 20 and the inner cavity wall of the first cylindrical member 30, it is preferable that no member other than the conducting wire 40 is inserted. This is preferable because in the insertion passage 35, the conducting wire 40 is not entangled with other members and the insertion of the conducting wire 40 is not obstructed by other members.

[0053] As shown in FIG. 6, in a cross section perpendicular to the longitudinal axis direction x, the length L obtained by subtracting the length L2 between two points where the straight line B passing through the centroid C of the inner shaft 20 intersects the outer wall of the inner shaft 20 from the length L5 between two points where the straight line B passing through the centroid C of the inner shaft 20 intersects the inner cavity wall of the outer shaft 10 5-2 is preferably at least twice the major diameter of the conducting wire 40. The length L 5-2 is more preferably at least 2.5 times the major diameter of the conducting wire 40, and even more preferably at least 3 times. Also, the length L 5-2 is preferably at most 6 times the major diameter of the conducting wire 40, more preferably at most 5 times, and even more preferably at most 4 times. When the length L 5-2 is within the above range, it becomes easy to manufacture the distal portion of the electrode catheter 1 such that the electrode 50 is disposed at the distal portion of the outer shaft 10 and the conducting wire 40 connected to the electrode 50 extends into the inner cavity of the outer shaft 10 through the measurement hole provided in the outer shaft 10.

[0054] Although FIG. 3 to FIG. 5 do not show the length L5, in the section proximal to the distal end of the first cylindrical member 30 in the longitudinal axis direction x, the length L 5-2 is preferably within the above range. Even when the length L 5-2 is within the above range, in the embodiment of the present invention, since the first cylindrical member 30 is disposed, the insertion passage 35 of the conducting wire 40 can be defined, and the kinking and vibration of the conducting wire 40 can be suppressed.

[0055] Although not shown, in a cross section perpendicular to the longitudinal axis direction x, when at least one of the outer surface of the inner shaft 20 and the inner cavity wall of the outer shaft 10 has a shape deviating from a perfect circle, the length L 5-2 is not uniquely determined depending on how the straight line B is drawn. In this case, the length L 5-2 when the straight line B is drawn such that the length L is maximized5-2 Preferably, it has the above range.

[0056] In the longitudinal axis direction x, the length of the first cylindrical member 30 is preferably 50% or more of the length from the proximal end of the electrode 50 disposed closest to the proximal side to the proximal end of the outer shaft 10, more preferably 70% or more, still more preferably 80% or more, and may be 100%, that is, the proximal end of the first cylindrical member 30 may be arranged at the same position as the proximal end of the outer shaft 10. Since the first cylindrical member 30 has a length of a predetermined length or more in the longitudinal axis direction x, an insertion passage 35 for the conducting wire 40 can be defined by the inner cavity wall of the first cylindrical member 30 in a section having a length of a predetermined length or more in the longitudinal axis direction x, and the twisting and vibration of the conducting wire 40 can be more effectively suppressed.

[0057] Alternatively, the first cylindrical member 30 may extend to a position more proximal than the proximal end of the outer shaft 10. Thereby, it becomes possible to dispose the proximal end portion of the conducting wire 40 connected to an external device disposed more proximal than the proximal end of the outer shaft 10 in the inner cavity of the first cylindrical member 30, and twisting and vibration can be prevented over the entire length of the conducting wire 40.

[0058] In the longitudinal axis direction x, the length S1 from the proximal end of the electrode 50 disposed closest to the proximal side to the distal end of the first cylindrical member 30 is preferably 5 times or less the length S2 from the distal end of the outer shaft 10 to the proximal end of the electrode 50 disposed closest to the proximal side. The length S1 is more preferably 3 times or less the length S2, still more preferably 2 times or less, and may be 1 time or less, 1 / 2 or less, 1 / 3 or less. Also, the lower limit of the length S1 is not particularly limited, and may be, for example, 1 / 10 or more, 1 / 8 or more, 1 / 5 or more of the length S2. FIG. 6 shows a section in which the insertion passage of the conducting wire 40 is not defined by the first cylindrical member 30 between the proximal end of the electrode 50 disposed closest to the proximal side and the distal end of the first cylindrical member 30. However, if the length S1 is within the above range, such a section in which the insertion passage of the conducting wire 40 is not defined by the first cylindrical member 30 can be shortened, and the twisting and vibration of the conducting wire 40 can be more easily prevented.

[0059] As shown in FIG. 7, the electrode catheter 1 further has a second cylindrical member 60 disposed outside the inner shaft 20, and it is preferable that the distal end of the first cylindrical member 30 is located proximal to the distal end of the second cylindrical member 60. For example, the distal end of the second cylindrical member 60 is arranged near the distal end of the inner shaft 20, the proximal end of the second cylindrical member 60 is arranged near the proximal end of the inner shaft 20, and the second cylindrical member 60 may be arranged so as to overlap 80% or more, 90% or more, or 100% of the portion outside the inner shaft 20. By arranging the second cylindrical member 60 outside the inner shaft 20, for example, even when the electrode catheter 1 is bendable and the inner shaft 20 has a coil configuration, it is possible to prevent the coil from bulging outward in the radial direction y when the electrode catheter 1 is bent.

[0060] Regarding the material constituting the second cylindrical member 60, reference can be made to the description of the material constituting the first cylindrical member 30. The second cylindrical member 60 may be in contact with the outer surface of the inner shaft 20.

[0061] In the case of the above configuration, as shown in FIG. 8, the insertion passage 35 for the lead wire 40 can be defined by the outer surface of the second cylindrical member 60 and the inner cavity wall of the first cylindrical member 30. In this case, since the width of the insertion passage 35 can be further narrowed by the thickness of the second cylindrical member 60 from the length L 1-2 it is possible to more easily prevent the lead wire 40 from being twisted or vibrating. However, since the second cylindrical member 60 is arranged outside the inner shaft 20 having a certain rigidity, even if the second cylindrical member 60 has the same constituent material and thickness as the first cylindrical member 30, the second cylindrical member 60 cannot define the insertion passage 35 for the lead wire 40 as flexibly as the first cylindrical member 30. Therefore, for example, even if the insertion passage for the lead wire 40 is defined by the outer surface of the second cylindrical member 60 and the inner cavity wall of the outer shaft 10 without providing the first cylindrical member 30, the object of the present invention cannot be achieved, and it is important that the insertion passage 35 for the lead wire 40 is defined by the inner cavity wall of the first cylindrical member 30 in the present invention.

[0062] As shown in FIG. 9, the electrode catheter 1 has a second cylindrical member 60 disposed outside the inner shaft 20, and the distal end of the first cylindrical member 30 is preferably located proximal to the proximal end of the second cylindrical member 60. Thereby, the second cylindrical member 60 can be disposed on the distal end side of the inner shaft 20. For example, even when the electrode catheter 1 is bendable and the inner shaft 20 is a coil, when the electrode catheter 1 is bent, the distal portion of the inner shaft 20, which is the proximal end of the bend, can be prevented from bulging outward in the radial direction y.

[0063] As shown in FIG. 10, in the case of the above configuration, in the longitudinal axis direction x, in a cross section perpendicular to the longitudinal axis direction x of the section where the second cylindrical member 60 is disposed, from the length L3 between two points where a straight line B passing through the center of the inner shaft 20 intersects the inner cavity wall of the outer shaft 10, the length L obtained by subtracting the length L4 between two points where the straight line B intersects the outer wall of the second cylindrical member 60 3-4 is preferably not more than three times the major diameter of the lead wire 40. At this time, the second cylindrical member 60 is preferably disposed in a section of length S1 from the proximal end of the electrode 50 disposed closest proximally to the distal end of the first cylindrical member 30. Since the distal end of the first cylindrical member 30 is located proximal to the proximal end of the second cylindrical member 60, in the section where the second cylindrical member 60 is disposed in the longitudinal axis direction x, the insertion passage 65 for the lead wire 40 is not defined by the first cylindrical member 30. However, with the above configuration, in this section, the outer surface of the second cylindrical member 60 and the inner cavity wall of the outer shaft 10 can define the insertion passage 65 for the lead wire 40. Since the defined insertion passage 65 has a width of a predetermined value or less, the lead wire 40 can be suppressed from being twisted or vibrating even in the proximal section where the first cylindrical member 30 is not disposed, and the noise of the signal transmitted from or to the electrode 50 through the lead wire 40 can be reduced.

[0064] Length L 3-4 is preferably not more than 2.5 times the major diameter of the lead wire 40, more preferably not more than 2.2 times, and may be not more than 2.1 times. Length L 3-4If it is within the above range, the above effects can be achieved. At this time, as shown in FIG. 10, the conducting wire 40 may be one, or although not shown, the conducting wire 40 may be two or more. When there are two conducting wires 40, for example, the conducting wires 40 can be arranged at positions shifted by 180° in the circumferential direction of the inner shaft 20, and it is possible to prevent these conducting wires 40 from being twisted or vibrating in the radial direction y in the insertion passage 65. Further, even when the electrode catheter 1 has three or more conducting wires 40, by arranging these three or more conducting wires 40 at intervals in the circumferential direction of the inner shaft 20, the conducting wires 40 can be arranged in the insertion passage 65 defined to have a width of a predetermined value or less, and it is possible to prevent the plurality of conducting wires 40 from being twisted or vibrating in the radial direction y in the insertion passage 65.

[0065] Also, the length L 3-4 may be not more than twice, not more than 1.5 times, or not more than 1.2 times the conducting wire 40. The length L 3-4 If the upper limit is within the above range, for example, as shown in FIG. 10, when the electrode catheter 1 has one conducting wire 40, the width of the insertion passage 65 of the conducting wire 40 can be made a predetermined value or less, and it is possible to prevent the conducting wire 40 from being twisted or vibrating in the radial direction y in the insertion passage 65. Further, even when the electrode catheter 1 has two or more conducting wires 40, by arranging these plurality of conducting wires 40 biased in a part of the circumferential direction of the inner shaft 20, the plurality of conducting wires 40 can be arranged in the insertion passage 65 defined to have a width of a predetermined value or less, and it is possible to prevent the conducting wires 40 from being twisted or vibrating in the radial direction y in the insertion passage 65. In this case, for example, the plurality of conducting wires 40 may be arranged with a shift of 15°, 20°, or 30° in the circumferential direction of the inner shaft 20.

[0066] The length L 3-4 is preferably not less than one time, more preferably not less than 1.1 times the conducting wire 40. The length L 3-4 If the lower limit is within the above range, the conducting wire 40 can be easily inserted into the insertion passage 65.

[0067] Although not shown, when at least one of the outer surface of the second cylindrical member 60 and the inner cavity wall of the outer shaft 10 has a shape deviating from a perfect circle in a cross section perpendicular to the longitudinal axis direction x, the length L depends on how the straight line B is drawn. 3-4 is not uniquely determined. In this case, the length L 3-4 is preferably within the above range when the straight line B is drawn such that the length L 3-4 is maximized.

[0068] However, even when the length L 3-4 is within the above range, since the second cylindrical member 60 is arranged outside the inner shaft 20 having a certain rigidity, even if the second cylindrical member 60 has the same constituent material and thickness as the first cylindrical member 30, the second cylindrical member 60 cannot define the insertion passage 65 for the conducting wire 40 as flexibly as the first cylindrical member 30. Therefore, it is preferable that the length in the longitudinal axis direction x of the insertion passage 65 defined by the second cylindrical member 60 is short, and the length in the longitudinal axis direction x of the insertion passage 65 is preferably 5 times or less the length S2 from the distal end of the outer shaft 10 to the proximal end of the electrode 50 arranged closest to the proximal side. The length in the longitudinal axis direction x of the insertion passage 65 is more preferably 4 times or less of S2, and even more preferably 3 times or less. Also, the length in the longitudinal axis direction x of the insertion passage 65 is preferably 1 / 2 or more of S2, and more preferably 1 time or more. Thereby, the length in the longitudinal axis direction x of the insertion passage 65 defined by the second cylindrical member 60 can be made to be a certain length or less, and it is preferable because the conducting wire 40 proximal to the proximal end of the second cylindrical member 60 can be inserted into the insertion passage 35 defined by the first cylindrical member 30. The length in the longitudinal axis direction x of the insertion passage 65 in this embodiment can also be referred to as the length in the longitudinal axis direction x of the second cylindrical member 60.

[0069] The conducting wire 40 is preferably arranged at the same circumferential position of the inner shaft 20 in the insertion passage 35 and the insertion passage 65. Thereby, the conducting wire 40 can be made to travel straight from the distal side to the proximal side.

[0070] In the longitudinal axis direction x, the length S3 from the proximal end of the second cylindrical member 60 to the distal end of the first cylindrical member 30 is preferably not more than twice the length S2 from the distal end of the outer shaft 10 to the proximal end of the electrode 50 disposed closest to the proximal side. The length S3 is more preferably not more than 1.5 times the length S2, still more preferably not more than 1 time, and may be not more than 4 / 5. The lower limit of the length S3 is not particularly limited, and for example, it may be not less than 1 / 5 of S2 or not less than 2 / 5. As shown in FIG. 9, the section of the length S3 is the section between the insertion passage 35 of the conducting wire 40 defined by the first cylindrical member 30 and the insertion passage 65 of the conducting wire 40 defined by the second cylindrical member 60. In this section, the insertion passage of the conducting wire 40 is not defined by either the first cylindrical member 30 or the second cylindrical member 60, and play occurs around the conducting wire 40. By setting the length S3 within the above range, the length in the longitudinal axis direction x of this section can be made not more than a predetermined value, and it becomes possible to more easily prevent the twisting and vibration of the conducting wire 40.

[0071] As shown in FIGS. 2, 9, 11, and 12, in the longitudinal axis direction x, when the length from the distal end of the outer shaft 10 to the distal end of the first cylindrical member 30 is d, the outer shaft 10 and the first cylindrical member 30 are not fixed on the distal side of the point D which is d closer to the proximal side from the distal end of the first cylindrical member 30, and it is preferable to have a fixing portion 31 where the outer shaft 10 and the first cylindrical member 30 are fixed on the proximal side of the point D of the first cylindrical member 30.

[0072] Since the outer shaft 10 and the first cylindrical member 30 are not fixed on the distal side of the point D of the first cylindrical member 30, the distal side of the first cylindrical member 30 can move relative to the outer shaft 10, and the flexibility of the distal side of the first cylindrical member 30 can be ensured. On the distal side of the point D, the outer surface of the first cylindrical member 30 and the inner cavity wall of the outer shaft 10 may be in contact with each other entirely or partially as long as they are not fixed, but it is preferable that the outer surface of the first cylindrical member 30 and the inner cavity wall of the outer shaft 10 are not in contact with each other. With such a configuration, even when the insertion passage 35 of the lead wire 40 bends following the bending of the electrode catheter 1 in a blood vessel, the first cylindrical member 30 can easily follow the bending, and it becomes easier to define the insertion passage 35 of the lead wire 40 arranged outside the inner shaft 20 by the first cylindrical member 30. In addition, since it becomes easier to ensure the flexibility of the first cylindrical member 30, damage to the lead wire 40 can be more easily prevented.

[0073] By having the fixing portion 31 where the outer shaft 10 and the first cylindrical member 30 are fixed on the proximal side of the point D of the first cylindrical member 30, it is possible to prevent the first cylindrical member 30 from shifting in the longitudinal axis direction x or rotating in the circumferential direction. The fixing portion 31 is preferably provided by fixing it by some fixing means such as adhesion with an adhesive or welding with a resin.

[0074] The fixing portion 31 is preferably provided by fixing the inner cavity wall of the outer shaft 10 and the outer surface of the first cylindrical member 30. One fixing portion 31 may be provided, or a plurality of fixing portions 31 may be provided. When a plurality of fixing portions 31 are provided, it is preferable that the plurality of fixing portions 31 are spaced apart from each other. The fixing portion 31 may be provided over the entire circumferential direction of the outer peripheral surface of the first cylindrical member 30 as shown in FIG. 11. If the fixing portion 31 is provided over the entire circumferential direction, the fixing strength can be improved. Alternatively, the fixing portion 31 may be provided on a part of the circumferential direction of the outer peripheral surface of the first cylindrical member 30 as shown in FIG. 12. If the fixing portion 31 is provided on a part of the circumferential direction, it becomes easy to ensure the flexibility of the first cylindrical member 30 even at the portion where the fixing portion 31 is provided.

[0075] In the longitudinal axis direction x, the length of the fixing portion 31 is not particularly limited, but the length of one fixing portion 31 is preferably at least 1 / 2 of the length of one electrode 50, and more preferably 1 time or more. Thereby, the fixing strength can be improved. Further, in the longitudinal axis direction x, the length of one fixing portion 31 is preferably 1 time or less, and more preferably 1 / 2 or less of the length S1 from the proximal end of the electrode 50 arranged closest to the proximal side to the distal end of the first cylindrical member 30. Thereby, the flexibility of the first cylindrical member 30 can be improved.

[0076] The first cylindrical member 30 is preferably not fixed to the inner shaft 20. It is preferable that the first cylindrical member 30 is not fixed to the inner shaft 20 because the flexibility of the first cylindrical member 30 is improved. Further, if the first cylindrical member 30 is fixed to the inner shaft 20, a fixing portion will be provided in the insertion passage 35 of the conducting wire 40 between the outer surface of the inner shaft 20 and the inner cavity wall of the first cylindrical member 30, and thus the conducting wire 40 will also be fixed. However, since the first cylindrical member 30 is not fixed to the inner shaft 20, the conducting wire 40 can be easily inserted into the insertion passage 35. For example, even when the electrode catheter 1 is curved, the conducting wire 40 is not pulled by the fixing and it is easy to maintain the flexibility of the catheter 1.

[0077] The inner shaft 20 may be fixed to the outer shaft 10 on the distal side of the distal end of the first cylindrical member 30 in the longitudinal axis direction x. Thereby, the rotation of the inner shaft 20 can be suppressed. Alternatively, the inner shaft 20 may be fixed to the first cylindrical member 30 on the proximal side of the distal end of the first cylindrical member 30 in the longitudinal axis direction x and indirectly fixed to the outer shaft 10. At this time, the inner shaft 20 and the first cylindrical member 30 may be fixed to the conducting wire 40, or the inner shaft 20 and the first cylindrical member 30 may be fixed at a portion where the conducting wire 40 is not arranged. In the above, the inner shaft 20 may be indirectly fixed to the first cylindrical member 30 and / or the outer shaft 10 via the second cylindrical member 60.

Explanation of Reference Numerals

[0078] 1: Electrode catheter 7: Handle 10: Outer shaft 11: Tip 20: Inner shaft 21: Elastic member 22: Wire 30: First cylindrical member 31: Fixed part 35: Insertion path for the conducting wire 40: Conducting wire 50: Electrode 60: Second cylindrical member 65: Insertion path for the conducting wire B: Straight line passing through the centroid of the inner shaft C: Centroid of the inner shaft d: Length from the distal end of the outer shaft to the distal end of the first cylindrical member D: Point at a distance d proximally from the distal end of the first cylindrical member S1: Length from the proximal end of the most proximally arranged electrode to the distal end of the cylindrical member S2: Length from the distal end of the outer shaft to the proximal end of the most proximally arranged electrode S3: Length from the proximal end of the second cylindrical member to the distal end of the second cylindrical member x: Longitudinal axis direction y: Radial direction

Claims

1. An outer shaft having a distal end and a proximal end in the longitudinal axis direction and having a lumen extending in the longitudinal axis direction, An inner shaft extending into the lumen of the outer shaft, One or more electrodes disposed at the distal portion of the outer shaft, A first cylindrical member having a distal end and a proximal end in the longitudinal axis direction and having a lumen extending in the longitudinal axis direction, wherein the inner shaft is disposed within the lumen of the first cylindrical member and is disposed outside the lumen of the outer shaft and outside the inner shaft, and the distal end of the first cylindrical member is located proximal to the proximal end of the most proximal electrode among the one or more electrodes. A first cylindrical member, A wire connected to the electrode and extending within the lumen of the outer shaft outside the inner shaft and within the lumen of the first cylindrical member, A second cylindrical member disposed outside the inner shaft, The distal end of the first cylindrical member is located proximal to the distal end of the second cylindrical member, In a cross-section perpendicular to the longitudinal axis direction, the length obtained by subtracting the length between two points where the straight line passing through the centroid of the inner shaft intersects the outer wall of the inner shaft from the length between two points where the straight line passing through the centroid of the inner shaft intersects the inner wall of the first cylindrical member is three times or less the major diameter of the wire. An electrode catheter.

2. The electrode catheter according to claim 1, wherein in the longitudinal axis direction, the length of the first cylindrical member is 50% or more of the length from the proximal end of the most proximal electrode to the proximal end of the outer shaft.

3. The electrode catheter according to claim 1 or 2, wherein in the longitudinal axis direction, the length from the proximal end of the most proximal electrode to the distal end of the first cylindrical member is 5 times or less the length from the distal end of the outer shaft to the proximal end of the most proximal electrode.

4. The electrode catheter according to any one of claims 1 to 3, wherein the distal end of the first cylindrical member is located proximal to the proximal end of the second cylindrical member.

5. In a cross-section perpendicular to the longitudinal axis direction of the section where the second cylindrical member is disposed in the longitudinal axis direction, the length obtained by subtracting the length between two points where the straight line passing through the centroid of the inner shaft intersects the outer wall of the second cylindrical member from the length between two points where the straight line passing through the centroid of the inner shaft intersects the inner wall of the outer shaft is three times or less the major diameter of the wire. The electrode catheter according to claim 4.

6. In the longitudinal axis direction, the length from the proximal end of the second cylindrical member to the distal end of the first cylindrical member is not more than twice the length from the distal end of the outer shaft to the proximal end of the most proximally arranged electrode, according to the electrode catheter of claim 4 or 5.

7. In the longitudinal axis direction, when the length from the distal end of the outer shaft to the distal end of the first cylindrical member is defined as d, the outer shaft and the first cylindrical member are not fixed on the distal side of a point D which is d away proximally from the distal end of the first cylindrical member, and the outer shaft and the first cylindrical member are fixed on the proximal side of the point D of the first cylindrical member, having a fixing portion, according to the electrode catheter of any one of claims 1 to 6.

8. The first cylindrical member is not fixed to the inner shaft, according to the electrode catheter of any one of claims 1 to 7.

9. The first cylindrical member extends to a position more proximal than the proximal end of the outer shaft, according to the electrode catheter of any one of claims 1 to 8.

10. The first cylindrical member is composed of at least one polymer or elastomer selected from the group consisting of polyolefin resins, polyamide resins, polyimide resins, polyester resins, polyurethane resins, vinyl chloride resins, silicone resins, polycarbonate resins, and aromatic polyether ketone resins, according to the electrode catheter of any one of claims 1 to 9.

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