Medical device

Abstract

Provided is a medical device capable of preventing an electrode part from falling off from an expansion body while facilitating arrangement of the electrode part from the inside to the outside of the expansion body.　Provided is a medical device (10) comprising a shaft part (20) and an electrode assembly (70) having an electrode part (22), wherein an expansion body (21) has a first through-hole (61) through which the electrode assembly (70) is inserted, and a second locking part (68) that locks the electrode assembly (70) such that the electrode part (22) is arranged outside the expansion body (21); the first through-hole (61) has a maximum length (L1) along a first extension direction (X1), and has a maximum width (W1) along a first width direction (Y1); the electrode assembly (70) has an electrode arrangement part (72) and a wiring part (71); the electrode arrangement part (72) includes a first end (79) in a second extension direction (X2) and a second end (80) on the side opposite to the first end (79); the electrode part (22) is arranged through the electrode arrangement part (72); the wiring part (71) includes a first connection part (76) connected to the first end (79) of the electrode arrangement part (72); the wiring part (71) extends inside the expansion body (21) toward the shaft part (20); the electrode arrangement part (72) has a maximum width (W2); the first end (79) of the electrode arrangement part (72) has a width (W3); the first connection part (76) has a maximum width (W4); and L1 > W2 ≥ W3 > W1 > W4 is satisfied.

Description

Medical device

[0001] The present invention relates to a medical device that imparts energy to living tissue.

[0002] As a medical device, there is known one that performs ablation treatment for cauterizing living tissue with a high-frequency current from an electrode part, where the electrode part is arranged on an expander that expands and contracts inside the body. As one of the treatments by ablation, shunt treatment for the atrial septum is known. Shunt treatment forms a shunt (communication hole) in the oval fossa of the atrial septum as a escape route for the elevated atrial pressure for patients with heart failure, enabling alleviation of heart failure symptoms. In shunt treatment, access to the atrial septum is made by a transvenous approach to form a shunt of a desired size.

[0003] The expander has a recess that is recessed radially inward when the expander expands, defining a receiving space capable of receiving living tissue, and can sandwich the living tissue from both sides in the thickness direction. The electrode part is arranged in the recess. Each electrode part forms an electrode assembly together with a long wiring part for supplying current. Such a medical device is disclosed in, for example, Patent Document 1.

[0004] International Publication No. 2019 - 085841

[0005] Since the expander arranges a large number of electrode parts in the circumferential direction, the linear body forming the expander has a complex shape in which it branches and merges along the length direction. In this case, since it is difficult to arrange the electrode assembly along the expander, the electrode assembly is separate from the linear body. When the electrode assembly is arranged separately from the linear body of the expander in this way, the operation of attaching the electrode assembly to the expander is complicated, and there is a possibility that the electrode assembly may fall off from the expander.

[0006] The present invention has been made to solve the above-described problems, and an object thereof is to provide a medical device that can easily arrange the electrode part from the inside to the outside of the expander and prevent the electrode part from falling off from the expander.

[0007] A medical device (1) according to the present invention that achieves the above objective comprises: an elongated shaft portion; an expandable body connected to the tip of the shaft portion and expandable and contractible in the radial direction; and at least one electrode assembly having an electrode portion for applying energy to biological tissue, extending elongatedly from the shaft portion to the outside of the expandable body, wherein the expandable body has a first through hole through which the at least one electrode assembly is inserted from the inside to the outside of the expandable body, and a locking portion for locking the at least one electrode assembly so that the electrode portion is positioned on the outside of the expandable body, the first through hole having a maximum length L1 along a first extending direction in which the outer surface of the expandable body extends from the base end to the tip, and a maximum width W1 along a first width direction perpendicular to the first extending direction, The electrode assembly comprises at least one electrode assembly having an electrode placement section where the electrode portion is arranged, including a first end in a second extending direction in which the electrode assembly extends and a second end opposite to the first end in the second extending direction; and a wiring section extending inside the extension toward the shaft portion, including a first connecting section connected to the first end of the electrode placement section, wherein the electrode placement section has a maximum width W2 along a second width direction perpendicular to the second extending direction, the first end of the electrode placement section has a width W3 along the second width direction, and the first connecting section of the wiring section has a maximum width W4 along the second width direction, and the maximum length L1 of the first through hole, the maximum width W1 of the first through hole, the maximum width W2 of the electrode placement section, the width W3 of the first end of the electrode portion, and the maximum width W4 of the first connecting section satisfy the following equation: L1 > W2 ≥ W3 > W1 > W4

[0008] The medical device (1) configured as described above can be assembled to the expandable body by adjusting the positional relationship between the electrode assembly and the expandable body so that the second width direction approaches the first extending direction, thereby passing the electrode placement section having a maximum width W2 along the second width direction through the first through hole having a maximum length L1 along the first extending direction. Furthermore, the first connecting section of the wiring section having a maximum width W4 can be placed in the first through hole having a maximum width W1, and the first end of the electrode placement section having a width W3 is prevented from passing through the first through hole having a maximum width W1, thereby preventing the electrode section from being pulled inward from the first through hole to the inside of the expandable body. Thus, the medical device can facilitate the placement of the electrode section on the outside of the expandable body while preventing the electrode section from being pulled inward from the expandable body.

[0009] (2) In the medical device described in (1) above, the first through-hole has a first section in which the maximum width W1 is formed, and a second section extending from the first section along the first extending direction and together with the first section defining the maximum length L1 of the first through-hole, wherein the width W5 of the second section along the first width direction may be smaller than the maximum width W4 of the first connecting portion. This allows the medical device to have the first connecting portion placed in the first section, and prevents the electrode portion, which is placed on the outside of the expandable body, from being pulled inward or shifted toward the second section.

[0010] (3) In the medical device described in (1) or (2) above, the maximum distance L2 from the boundary edge at the boundary between the second section and the first section to the edge of the first section on the opposite side of the boundary edge in the first extending direction may be narrower than the maximum width W4 of the first connecting portion. This prevents the first connecting portion, which is arranged in the first section, from rotating within the first section so that the second width direction approaches the first extending direction, thereby preventing the first connecting portion from shifting toward the second section or shifting toward the inside or outside of the expansion body. As a result, the medical device can better prevent displacement of the electrode portion arranged outside the expansion body.

[0011] (4) In the medical device described in any one of (1) to (3) above, the at least one electrode assembly includes a second connecting portion connected to the second end of the electrode placement portion and has an extending portion extending along the second extending direction, and the locking portion of the extension body may lock the extending portion. As a result, the medical device has a configuration in which the electrode portion is not directly fixed to the extension body, so that problems such as damage to the electrode portion or the electrode portion being covered with adhesive or the like for locking, which prevents energy from being applied to biological tissue, can be prevented.

[0012] (5) In the medical device described in (4) above, the expandable body has a recess that is recessed radially inward when the expandable body is expanded, the recess has a bottom portion located at the innermost part in the radial direction, a base-side upright portion extending from the base end of the bottom toward the base-side top portion radially outward, and a tip-side upright portion extending from the tip of the bottom toward the tip-side top portion radially outward, the first through hole of the expandable body is provided in the base-side upright portion such that the electrode portion is positioned along the base-side upright portion, and the locking portion of the expandable body may lock the extended portion at a position adjacent to the bottom of the tip-side upright portion. As a result, the medical device can position the electrode portion along the base-side upright portion in close proximity to the bottom of the recess.

[0013] (6) In the medical device described in (5) above, the tip-side upright portion of the expandable body has a second through-hole at the position adjacent to the bottom portion through which the extended portion is inserted from the inside to the outside of the expandable body, the locking portion is formed from the edge of the second through-hole, the extended portion has a second locking portion at the end of the second connecting portion opposite to the electrode placement portion in the second extending direction, which engages from the inside of the expandable body with the edge of the second through-hole where the locking portion is formed, the second through-hole has a maximum width W6 along the first width direction, the second connecting portion of the extended portion has a maximum width W7 along the second width direction, and the second locking portion of the extended portion has a maximum width W8 along the second width direction, and the maximum width W6 of the second through-hole, the maximum width W7 of the second connecting portion, and the maximum width W8 of the second locking portion may satisfy the following equation, W8 > W6 > W7. As a result, the second connecting portion having a maximum width W7 can be positioned in the second through-hole having a maximum width W6, and the second locking portion having a maximum width W8 is prevented from passing through the second through-hole having a maximum width W6, thereby preventing the extended portion from being pulled out of the second through-hole to the outside of the expandable body. Therefore, the medical device can easily and reliably lock the second locking portion of the electrode assembly to the locking portion of the expandable body.

[0014] (7) In the medical device described in (6) above, the extension portion comprises an extension portion body including the second connecting portion, two second projections protruding from the second connecting portion of the extension portion body to both sides in the second width direction, and a slit provided between the two second projections in the second width direction, wherein the width of the extension portion body along the second width direction is smaller than the maximum width W6 of the second through hole, and the second locking portion may comprise the two second projections, a portion of the extension portion body positioned between the two second projections, and the slit. As a result, the extension portion can be easily displaced by the slit in a direction that brings the two second projections closer together in the second width direction, so that the second locking portion can be easily passed through the second through hole and the second locking portion can be securely locked to the edge of the second through hole from the inside of the extension.

[0015] (8) In the medical device described in (6) or (7) above, the second end of the electrode placement portion may have a width W9 formed wider than the maximum width W6 of the second through hole along the second width direction. This prevents the electrode portion placed on the outside of the expandable body from being pulled inward through the second through hole.

[0016] (9) In the medical device described in any one of (1) to (8) above, the wiring portion has a first locking portion at the end of the first connecting portion opposite to the electrode arrangement portion in the second extending direction, which engages with the edge of the first through hole from the inside of the expansion body, and the first locking portion of the wiring portion may have a width W10 formed wider than the maximum width W1 of the first through hole in the second width direction. This makes it difficult for the wiring portion of the electrode assembly to be pulled out to the outside of the expansion body in the medical device. As a result, the medical device can prevent the electrode portion from shifting position, the electrode assembly from bending significantly outside the expansion body and damaging biological tissue, and the electrode assembly itself from being damaged.

[0017] (10) In the medical device described in any one of (1) to (9) above, the wiring portion comprises a wiring portion body including the first connecting portion, and two first protrusions projecting from the connecting portion of the wiring portion body to both sides in the second width direction, the width of the extension portion body along the second width direction being smaller than the maximum width W1 of the first through hole, and the first locking portion may be formed from the two first protrusions and a portion of the extension portion body positioned between the two first protrusions. This allows the medical device to reliably engage the first locking portion with the edge of the first through hole from the inside of the extension.

[0018] This is a front view showing the overall configuration of the medical device according to the embodiment. This is an enlarged perspective view of the area near the expandable body. This is an enlarged front view of the area near the expandable body. This is an enlarged front view showing the shaft portion and a simplified representation of the expandable body. (A) is a plan view showing a part of the expandable body, and (B) is a plan view showing the tip of the electrode assembly. This is an enlarged perspective view of the area near the electrode portion of the expandable body. This is a plan view showing a part of the expandable body according to a modified example, where (A) is the first modified example, (B) is the second modified example, (C) is the third modified example, and (D) is the fourth modified example. This is an enlarged front view showing the shaft portion and a simplified representation of the expandable body of the medical device according to the fifth modified example. This is an enlarged front view showing the shaft portion and a simplified representation of the expandable body of the medical device according to the sixth modified example. This is an enlarged front view showing the shaft portion and a simplified representation of the expandable body of the medical device according to the seventh modified example. This is an enlarged front view showing the shaft portion and a simplified representation of the expandable body of the medical device according to the eighth modified example. This is an enlarged front view showing the shaft portion and a simplified representation of the expandable body of the medical device according to the ninth modified example. This is an explanatory diagram illustrating the state in which the expander is positioned in the atrial septum, with the medical device shown in a front view and the biological tissue in a cross-sectional view. This is an enlarged front view showing the state in which the expander grasps the biological tissue. This is a front view showing the overall configuration of the medical device according to the 10th modified example.

[0019] Embodiments of the present invention will be described below with reference to the drawings. Note that the dimensional ratios in the drawings may be exaggerated for illustrative purposes and may differ from the actual ratios. In this specification, the side of the medical device that is inserted into the lumen of a living body will be referred to as the "tip" or "tip side," and the side that is operated by the user will be referred to as the "proximal end" or "proximal end."

[0020] The medical device 10 according to the following embodiment is configured to expand a first opening Hh1 formed in the atrial septum HA of the patient's heart H into a second opening Hh2, and then to maintain the expanded second opening Hh2 at its size by performing maintenance procedures to create a communication hole Hh.

[0021] As shown in Figure 1, the medical device 10 of this embodiment includes a hollow, elongated shaft portion 20, an extension body 21 provided at the tip of the shaft portion 20, at least one electrode assembly 70 on which an electrode portion 22, which is an energy transfer element for performing maintenance procedures, is provided, and a handheld operating portion 23 provided at the base end of the shaft portion 20.

[0022] The shaft portion 20 has a hollow tip extension 30 at its tip that extends inward from the base end of the expandable body 21. The tip extension 30 extends along the central axis of the expandable body 21 from near the base end of the expandable body 21 to partway along the expandable body 21, specifically to the vicinity of the recess 51 of the expandable body 21. The shaft portion 20 also has a connecting portion 28 that is connected to the base end of the expandable body 21.

[0023] A storage sheath 25 is provided on the outer circumference of the shaft portion 20. The shaft portion 20 is movable axially relative to the storage sheath 25. When the storage sheath 25 is moved toward the tip of the shaft portion 20, the expandable body 21 can be stored inside it. By moving the storage sheath 25 toward the base end from the state in which the expandable body 21 is stored, the expandable body 21 can be exposed.

[0024] Inside the shaft portion 20, a traction shaft 26 is slidably positioned relative to the shaft portion 20. The traction shaft 26 extends from the base end of the hand-operated section 23 to the tip end of the extension body 21. The traction shaft 26 protrudes from the tip of the shaft portion 20, specifically from the tip extension portion 30, passes inside the extension body 21, and protrudes from the tip of the extension body 21. The tip of the traction shaft 26 is fixed to the tip member 35.

[0025] The tip member 35, to which the tip of the traction shaft 26 is fixed, does not need to be fixed to the expansion body 21. This allows the tip member 35 to exert a compressive force on the expansion body 21 along the axis of the shaft portion 20 as the traction shaft 26 slides relative to the shaft portion 20 in the base direction. Furthermore, when storing the expansion body 21 in the storage sheath 25, moving the tip member 35 away from the expansion body 21 towards the tip makes it easier for the expansion body 21 to move in the extension direction, thereby improving storage efficiency.

[0026] The handheld control unit 23 includes a housing 40 that is grasped by the operator, an operating dial 41 that can be rotated by the operator, and a conversion mechanism 42 that operates in conjunction with the rotation of the operating dial 41. The traction shaft 26 is held by the conversion mechanism 42 inside the handheld control unit 23. The conversion mechanism 42 can move the traction shaft 26 it holds forward and backward along the axial direction as the operating dial 41 rotates. For example, a rack and pinion mechanism can be used as the conversion mechanism 42.

[0027] The shaft portion 20 is preferably formed from a material having a certain degree of flexibility. Examples of such materials include polyolefins such as polyethylene, polypropylene, polybutene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ionomer, or mixtures of two or more of these; flexible polyvinyl chloride resin, polyamide, polyamide elastomer, polyester, polyester elastomer, polyurethane, fluororesins such as polytetrafluoroethylene, polyimide, PEEK, silicone rubber, latex rubber, and the like.

[0028] The traction shaft 26 can be formed from, for example, a superelastic alloy such as a nickel-titanium alloy or a copper-zinc alloy, a metallic material such as stainless steel, or a relatively rigid resin material.

[0029] The tip member 35 can be formed from, for example, superelastic alloys such as nickel-titanium alloy and copper-zinc alloy, metallic materials such as stainless steel, polymer materials such as polyolefin, polyvinyl chloride, polyamide, polyamide elastomer, polyurethane, polyurethane elastomer, polyimide, fluororesin, or mixtures thereof, or from a multilayer tube of two or more polymer materials.

[0030] As shown in Figures 2 to 6, the expandable body 21 has a plurality of linear bodies 50 in the circumferential direction. The linear bodies 50 branch and merge along the length direction between the connecting portion 28 to which the base end is connected and the tip converging portion 57 to which the tip is connected, thereby forming a mesh-like structure. As a result, the expandable body 21 can be expanded and contracted in the radial direction. The distance between adjacent linear bodies 50 in the circumferential direction among the plurality of linear bodies 50 constituting the expandable body 21 changes according to the expansion and contraction of the expandable body 21. The base end of the linear body 50 extends from the connecting portion 28 of the expandable body 21 toward the tip. The tip of the linear body 50 extends from the tip converging portion 57 of the expandable body 21 toward the base end. When the expandable body 21 is expanded, the linear body 50 has a base-side inclined portion 58 that widens in diameter from the base-side connecting portion 28 toward the base-side apex 54. Furthermore, the linear body 50 has a tip-side inclined portion 59 that widens in diameter from the tip-converging portion 57 toward the tip-side apex portion 55. The linear body 50 has a recess 51 in the axial center that is recessed radially inward of the expandable body 21. The innermost radial portion of the recess 51 is the bottom portion 56. The recess 51 defines a receptive space 24 capable of receiving biological tissue when the expandable body 21 expands.

[0031] The recess 51 has a proximal upright portion 52 that extends radially outward from the proximal end of the bottom portion 56 to the proximal top portion 54, and a distal upright portion 53 that extends radially outward from the distal end of the bottom portion 56. When the traction shaft 26 slides in the proximal direction relative to the shaft portion 20 and a compressive force is applied to the expandable body 21, the distal upright portion 53 and the proximal upright portion 52 move closer to each other and come into close contact with the biological tissue received in the receiving space 24. An electrode portion 22 is arranged along the recess 51 on the proximal upright portion 52 so as to face the receiving space 24. That is, the electrode portion 22 is provided in the middle of the central axis direction of the expandable body 21 so as to be exposed to the outside of the expandable body 21 along the expandable body 21. In this embodiment, 10 electrode portions 22 are provided along the circumferential direction. The electrode portion 22 may also be arranged on the distal upright portion 53.

[0032] The outer surface of the expanded body 21 extends along a first extending direction X1 from the base end to the tip end. The expanded body 21 has a first through hole 61 and a fourth through hole 62 formed in the base end upright portion 52, a second through hole 64 formed in the tip end upright portion 53, and a third through hole 63 formed in the bottom portion 56. The first through hole 61, the second through hole 64, the third through hole 63, and the fourth through hole 62 penetrate the expanded body 21 from the inside to the outside.

[0033] The first through-hole 61 is the portion through which the electrode assembly 70 is inserted and which holds the electrode assembly 70. The first through-hole 61 has a maximum length L1 along the first extending direction X1 in which the outer surface of the expandable body 21 extends from the base end to the tip of the expandable body 21, and has a maximum width W1 along the first width direction Y1 which is perpendicular to the first extending direction X1 and perpendicular to the radial direction centered on the axis of the shaft portion 20.

[0034] The first through-hole 61 has a first section 65 and a second section 66 which is shorter in length along the first width direction Y1 than the first section 65. In this embodiment, the second section 66 is located on the base end side of the first section 65.

[0035] The second section 66 communicates with the base end of the first section 65 and is formed so that it narrows on both sides in the first width direction Y1 from the first section 65. Therefore, the maximum width W1 of the first section 65, which is also the maximum width of the first through hole 61, is greater than the maximum width W5 of the second section 66. Also, in terms of length along the first extending direction X1, the first section 65 is shorter than the second section 66. The edges on both sides of the first section 65 along the first width direction Y1 form first locking portions 67 that hook and lock the electrode assembly 70.

[0036] The second through-hole 64 is the portion through which the electrode assembly 70 is inserted and which holds the electrode assembly 70. The second through-hole 64 is formed adjacent to the bottom 56 of the tip-side upright portion 53. The second through-hole 64 also serves to make the portion of the expanded body 21 connected to the bottom 56 easier to bend. The second through-hole 64 has a maximum width W6 along the first width direction Y1. The maximum length L3 of the second through-hole 64 along the first extending direction X1 is shorter than the maximum width W6 along the first width direction Y1. The edges on both sides of the second through-hole 64 along the first width direction Y1 form a second locking portion 68 (locking portion) that hooks and locks the electrode assembly 70.

[0037] The third through-hole 63 is formed in the bottom 56 of the expanded body 21 to make it easier to bend the bottom 56. However, the third through-hole 63 is not required to be formed.

[0038] The fourth through-hole 62 is formed between the first through-hole 61 and the third through-hole 63, adjacent to the bottom 56 of the base end upright portion 52. The fourth through-hole 62 serves to make the portion of the expanded body 21 connected to the bottom 56 easier to bend. Note that the fourth through-hole 62 may not be formed.

[0039] The linear body 50 forming the extended body 21 can be formed by laser cutting or the like from a single metal cylindrical member. The linear body 50 can be formed from a metallic material. Examples of this metallic material include titanium-based alloys (Ti-Ni, Ti-Pd, Ti-Nb-Sn, etc.), copper-based alloys, stainless steel, β-titanium steel, and Co-Cr alloys. It is preferable to use an alloy with spring properties such as nickel-titanium alloy. However, the material of the linear body 50 is not limited to these and may be formed from other materials.

[0040] Each electrode assembly 70 extends along a second extending direction X2 from the base end to the tip end. Preferably, each electrode assembly 70 is formed from a flexible printed circuit board (FPC). The electrode assembly 70 extends in a second width direction Y2 that is perpendicular to the second extending direction X2 and perpendicular to the radial direction centered on the axis of the shaft portion 20. Each electrode assembly 70 comprises a long wiring portion 71, an electrode placement portion 72 provided on the tip side of the wiring portion 71 where the electrode portion 22 is arranged, and an extending portion 73 provided on the tip side of the electrode placement portion 72. In the electrode assembly 70, the wiring portion 71 extends from the shaft portion 20, passes through the first through-hole 61 from the inside of the expansion body 21 to the outside of the expansion body 21, the electrode portion 22 and electrode placement portion 72 are located on the outside of the expansion body 21, and the extending portion 73 passes through the second through-hole 64 from the outside of the expansion body 21 to the inside of the expansion body 21.

[0041] The electrode portion 22 has an exposed conductive surface on the outer side of the electrode arrangement portion 72. The wiring portion 71 has an insulating layer covering its surface. The electrode assembly 70 is separate from the expansion body 21 and is attached to the expansion body 21.

[0042] The electrode unit 22 is connected to an external device, an energy supply device (not shown). A high-frequency voltage is applied from the energy supply device to the electrode pair consisting of the two electrode units 22, and energy is transferred between them. In other words, the electrode unit 22 is configured as a bipolar electrode. Note that the electrode unit 22 may also be a monopolar electrode. In this case, the electrode unit 22 is energized in relation to an external electrode.

[0043] The wiring portion 71 constituting the electrode assembly 70 has a wiring portion main body 74 extending along the second extending direction X2, and two first protrusions 75 protruding from both sides of the wiring portion main body 74 along the second width direction Y2. The wiring portion main body 74 has a first connecting portion 76 connected to the electrode arrangement portion 72, a base end connecting portion (not shown) on the opposite side of the first connecting portion 76, and a wire laying portion 77 disposed between the first connecting portion 76 and the base end connecting portion. The wiring portion 71 has a portion on the base end connecting portion side extending along the shaft portion 20, the wire laying portion 77 extending away from the shaft portion 20 inside the extension body 21 toward the recess 51 of the linear body 50, the first connecting portion 76 passing through the first through hole 61 of the base end side upright portion 52, and the electrode arrangement portion 72 having the electrode portion 22 being disposed outside the extension body 21. Between the connecting portion 28 of the extension body 21 and the tip of the tip extension portion 30, a tube-shaped tip covering portion 27 is provided for bundling and locking a plurality of wiring portions 71 of the plurality of electrode assemblies 70 on the outer surface of the tip extension portion 30. Therefore, the wiring portion 71 extends along the shaft portion 20 from the base end side to the tip side up to the tip position of the tip covering portion 27, and is separated from the shaft portion 20 on the tip side of the tip position of the tip covering portion 27. The tip covering portion 27 can be formed of the same resin material as the shaft portion 20.

[0044] The wiring portion 71 has a first locked portion 78 that contacts and is locked to the first locking portion 67 of the first through hole 61 from the inside of the extension body 21 at an end portion of the first connecting portion 76 on the side opposite to the electrode arrangement portion 72 in the second extending direction X2. The first locked portion 78 is formed by the two first protrusions 75 and a portion of the wiring portion main body 74 between the two first protrusions 75. The maximum width W10 of the first locked portion 78 along the second width direction Y2 is larger than the maximum width W4 of the first connecting portion 76 along the second width direction Y2.

[0045] The electrode arrangement portion 72 has a first end 79 in the second extending direction X2 and a second end 80 on the side opposite to the first end 79 in the second extending direction X2. The first end 79 is connected to the first connecting portion 76, and the second end 80 is connected to the extending portion 73. The electrode arrangement portion 72 has a maximum width W2 along the second width direction Y2. The first end 79 of the electrode arrangement portion 72 has a width W3 along the second width direction Y2, and the second end 80 has a width W9 along the second width direction Y2.

[0046] The first connecting portion 76 is disposed in the first section 65 of the first through hole 61. For this purpose, the maximum width W4 of the first connecting portion 76 is smaller than the maximum width W1 of the first section 65 of the first through hole 61 and larger than the maximum width W5 of the second section 66 of the first through hole 61. Thereby, the first connecting portion 76 is suppressed from moving to the second section 66 while being disposed in the first section 65 of the first through hole 61.

[0047] The maximum width W10 of the first engaged portion 78 located on both sides of the first connecting portion 76 along the second extending direction X2 and the maximum width W3 of the first end 79 of the electrode arrangement portion 72 are larger than the maximum width W1 of the first section 65 of the first through hole 61. Thereby, the first connecting portion 76 disposed in the first through hole 61 is suppressed from coming out of the first through hole 61 inwardly and outwardly.

[0048] The extending portion 73 has an extending portion main body 81 extending along the second extending direction X2 and two second protrusions 82 protruding from both sides of the extending portion main body 81 along the second width direction Y2. The extending portion main body 81 has a second connecting portion 83 connected to the electrode arrangement portion 72 and a slit 84 provided between the two second protrusions 82 in the second width direction Y2.

[0049] The extending portion 73 has a second engaged portion 85 that contacts and is engaged with the second locking portion 68 (locking portion) of the second through hole 64 from the inside of the expanding body 21 at an end of the second connecting portion 83 opposite to the electrode arrangement portion 72 in the second extending direction X2. The second engaged portion 85 is formed by the two second protrusions 82 and a portion of the extending portion main body 81 between the two protrusions.

[0050] The maximum width W8 of the second engaged portion 85 along the second width direction Y2 is larger than the maximum width W7 of the second connecting portion 83 along the second width direction Y2. The slit 84 facilitates deformation of the extending portion 73 so that the maximum width W8 of the two second protrusions 82 is reduced when the electrode assembly 70 is attached to the expanding body 21, making it easier to pass the two second protrusions 82 through the second through hole 64. The edge portions of the two second protrusions 82 on the side opposite to the second connecting portion 83 are inclined such that the widths of the two second protrusions 82 gradually decrease toward the tips. Thereby, the two second protrusions 82 can be smoothly passed through the second through hole 64.

[0051] The second connecting portion 83 is positioned in the second through-hole 64. For this reason, the maximum width W7 of the second connecting portion 83 is smaller than the maximum width W6 of the second through-hole 64.

[0052] The maximum width W8 of the second locking portion 85 located on both sides of the second connecting portion 83 along the second extending direction X2, and the width W9 of the second end 80 of the electrode placement portion 72 are greater than the maximum width W6 of the second through hole 64. This prevents the second connecting portion 83, which is positioned in the second through hole 64, from coming out of the second through hole 64 inwards and outwards.

[0053] The maximum length L1 of the first through-hole 61 along the first extending direction X1 is longer than the maximum width W8 of the second locking portion 85 of the electrode assembly 70 and longer than the maximum width W2 of the electrode placement portion 72. This makes it easy to pass the second locking portion 85 and the electrode placement portion 72 of the electrode assembly 70 through the first through-hole 61.

[0054] As shown in Figures 2 to 4, the shaft portion 20 on the proximal end side of the expansion body 21 has a tip extension portion 30 that extends to the inside of the expansion body 21 on the tip side of the connection portion 28, and a tip covering portion 27 that covers the proximal end of the tip extension portion on the tip side of the connection portion 28. The tip of the tip covering portion 27 is located on the proximal end side of the tip extension portion 30. The wiring portion 71 of the electrode assembly 70 is embedded between the tip covering portion 27 and the tip extension portion 30 of the shaft portion 20. As a result, the wiring portion 71 is bundled on the outer surface of the tip extension portion 30 located inside the expansion body 21. The position where the wiring portion 71 separates from the shaft portion 20 is located on the tip side of the connection portion 28 of the expansion body 21 because the wiring portion 71 is bundled on the inside of the expansion body 21 on the tip side of the connection portion 28 by the tip covering portion 27. In other words, the multiple wiring sections 71 are locked by the tip covering section 27 inside the expanded body 21 on the tip side of the expanded body 21, beyond the base end. As a result, the overhead wire section 77 of the wiring section 71 is positioned inside the expanded body 21, away from the inclined base end section 58 of the linear body 50, and extends toward the recess 51 in a suspended state. Therefore, when the expanded body 21 is in its expanded state, the overhead wire section 77 is not locked to either the expanded body 21 or the tip extension section 30. This makes it difficult for the wiring section 71 to come into contact with the inclined base end section 58 of the contracting linear body 50 when the radially expanded expanded body 21 is retracted into the storage sheath 25, thus preventing the wiring section 71 from interfering with the linear body 50 and being damaged.

[0055] As shown in Figures 4 to 6, the first through-hole 61 and the second through-hole 64 of the linear body 50 are through-holes that do not substantially change in shape or size whether the expanded body 21 is in an expanded or contracted state. The wiring portion 71 is inserted through the first through-hole 61, exposing the tip portion including the electrode portion 22 to the outside of the expanded body 21. The second through-hole 64, through which the extension portion 73 of the electrode assembly 70 that is closer to the tip than the electrode placement portion 72 is inserted, is located in the tip-side inclined portion 59, closer to the bottom 56 than the first through-hole 61. Therefore, the electrode assembly 70 that passes through the first through-hole 61 extends toward the bottom 56 of the recess 51.

[0056] As shown in the first modified example in Figure 7(A), the first through-hole 61 of the expansion body 21 may have a first section 65 that is wider in the first width direction Y1, and a second section 66 that is located closer to the tip than the first section 65 and is narrower than the first section 65.

[0057] Furthermore, as shown in the second modified example in Figure 7(B), the first through-hole 61 of the expansion body 21 may have a first section 65 that is wider in the first width direction Y1, and a second section 66 that is narrower than the first section 65 and is located both towards the tip and the base of the first section 65.

[0058] Furthermore, as shown in the third modified example in Figure 7(C), the first through-hole 61 of the expansion body 21 may have a first section 65 that is wider in the first width direction Y1, and a second section 66 that is located closer to the base end (and / or tip end) of the first section 65 than the first section 65, and is narrower than the first section 65.

[0059] Furthermore, as shown in the fourth modified example in Figure 7(D), the first through-hole 61 of the expansion body 21 may have only the first section 65.

[0060] Furthermore, as shown in the fifth modified example in Figure 8, the first through-hole 61 of the expansion body 21 into which the first connecting portion 76 of the electrode assembly 70 is locked is formed in the base end upright portion 52, and the second through-hole 64 into which the second connecting portion 83 of the electrode assembly 70 is locked may be formed closer to the bottom 56 of the base end upright portion 52, which is on the tip side of the first through-hole 61. The electrode assembly 70 reaches from the inside to the outside of the expansion body 21 through the first through-hole 61, extends toward the base end on the outside of the expansion body 21, and reaches from the outside to the inside of the expansion body 21 through the second through-hole 64. The electrode portion 22 is arranged in the electrode placement portion 72 so as to face outwards and toward the tip.

[0061] Furthermore, as shown in the sixth modified example in Figure 9, the first through-hole 61 of the expansion body 21 into which the first connecting portion 76 of the electrode assembly 70 is locked is formed at a position close to the bottom 56 of the tip-side upright portion 53 (or base-side upright portion 52), and the second through-hole 64 into which the second connecting portion 83 of the electrode assembly 70 is locked may be formed in the base-side upright portion 52, which is closer to the base end than the first through-hole 61. The electrode assembly 70 reaches from the inside to the outside of the expansion body 21 through the first through-hole 61, extends toward the base end on the outside of the expansion body 21, and reaches from the outside to the inside of the expansion body 21 through the second through-hole 64. The electrode portion 22 is arranged in the electrode placement portion 72 so as to face outwards and toward the tip.

[0062] Furthermore, as shown in the seventh modified example in Figure 10, the first through-hole 61 of the expansion body 21 into which the first connecting portion 76 of the electrode assembly 70 is locked is formed near the bottom 56 of the base-side upright portion 52 (or tip-side upright portion 53), and the second through-hole 64 into which the second connecting portion 83 of the electrode assembly 70 is locked may be formed in the tip-side upright portion 53, which is closer to the tip than the first through-hole 61. The electrode assembly 70 reaches from the inside to the outside of the expansion body 21 through the first through-hole 61, extends toward the base end on the outside of the expansion body 21, and reaches from the outside to the inside of the expansion body 21 through the second through-hole 64. The electrode portion 22 is arranged in the electrode placement portion 72 so as to face outwards and toward the base end.

[0063] Furthermore, as shown in the eighth modified example in Figure 11, the first through-hole 61 of the expansion body 21 into which the first connecting portion 76 of the electrode assembly 70 is locked is formed in the tip-side upright portion 53, and the second through-hole 64 into which the second connecting portion 83 of the electrode assembly 70 is locked may be formed closer to the bottom 56 of the base-side upright portion 52 (or tip-side upright portion 53) on the base end side than the first through-hole 61. The electrode assembly 70 reaches from the inside to the outside of the expansion body 21 through the first through-hole 61, extends toward the base end on the outside of the expansion body 21, and reaches from the outside to the inside of the expansion body 21 through the second through-hole 64. The electrode portion 22 is arranged in the electrode placement portion 72 so as to face outwards and toward the base end.

[0064] Furthermore, as shown in the ninth modified example in Figure 12, the first connecting portion 76 of the electrode assembly 70, which is on the base end side of the electrode portion 22, passes through the first through-hole 61 of the base end upright portion 52 of the expansion body 21 and is locked to the first through-hole 61. However, the part of the electrode assembly 70 that is on the tip side of the electrode portion 22 may be locked by being fixed to the expansion body 21. Therefore, the expansion body 21 does not need to have a second through-hole 64. The second locking portion 85 of the electrode assembly 70, which is located on the tip side of the electrode portion 22, is fixed to the second locking portion 68 (locking portion) located near the bottom portion 56 of the tip end upright portion 53 (or base end upright portion 52) of the expansion body 21 with an adhesive or the like. The second locking portion 85 of the electrode assembly 70 is fixed to the outer surface of the expansion body 21, but it may also be fixed to the inner surface of the expansion body 21, for example, by passing through the second through-hole 64.

[0065] Furthermore, the configuration in which the second locking portion 68 (locking portion) and the second locked portion 85 of the ninth modified example are fixed with an adhesive or the like may also be applied to the above-described embodiment, the first to eighth modified examples, etc.

[0066] When attaching the electrode assembly 70 to the expansion body 21, the worker twists the tip of the electrode assembly 70, including the extended portion 73 and the electrode placement portion 72, by approximately 90 degrees. This brings the second width direction Y2 of the electrode assembly 70 closer to the first extending direction X1 of the expansion body 21, as shown by the dashed line in Figure 6. In this state, the worker passes the tip of the electrode assembly 70, including the extended portion 73 and the electrode placement portion 72, through the first through hole 61 from the inside of the expansion body 21. At this time, the maximum length L1 of the first through hole 61 along the first extending direction X1 is longer than the maximum width W8 of the second locking portion 85 of the electrode assembly 70 and longer than the maximum width W2 of the electrode placement portion 72 (see Figure 5), so the worker can easily pass the extended portion 73 and the electrode placement portion 72 through the first through hole 61. Next, the worker straightens the electrode assembly 70 and positions the first connecting portion 76 into the first section 65 of the first through hole 61. This positions the first connecting portion 76 between the first locked portion 78 and the first end 79 into the first through hole 61 having the first locked portion 67. The maximum width W1 of the first through hole 61 is greater than the maximum width W4 of the first connecting portion 76, but smaller than the maximum width W10 of the first locked portion 78 and the width W3 of the first end 79. Therefore, the first connecting portion 76 is held securely without coming out of the first through hole 61 having the first locked portion 67.

[0067] Next, the worker passes the extended portion 73 of the electrode assembly 70 through the second through hole 64 from the outside of the expansion body 21. At this time, the extended portion 73 having the slit 84 can be deformed to reduce the width between the two second projections 82, so that it can easily pass through the second through hole 64. The second projections 82 that have passed through the second through hole 64 return to their original shape inside the expansion body 21. As a result, the second connecting portion 83 between the second locking portion 85 and the second end 80 is positioned in the first through hole 61 having the second locking portion 68 (locking portion). The maximum width W6 of the second through hole 64 is greater than the maximum width W7 of the second connecting portion 83, but is smaller than the maximum width W8 of the second locking portion 85 and the width W9 of the second end 80. Therefore, the second connecting portion 83 is stably held without coming out of the second through hole 64 having the second locking portion 68 (locking portion).

[0068] When using the medical device 10, a first opening Hh1 is formed in advance at the fossa ovale of the atrial septum HA. The medical device 10 expands and widens this first opening Hh1 to form a roughly circular second opening Hh2, and cauterizes the edge of the second opening Hh2. In this way, the medical device 10 forms a communication hole Hh that maintains its size, i.e., patency. As shown in Figure 13, the medical device 10 is delivered from the inferior vena cava IV through the right atrium HRa to the vicinity of the atrial septum HA, and the expander 21 is positioned at the location of the pre-formed first opening Hh1. The tip of the medical device 10 is designed to penetrate the atrial septum HA and reach the left atrium HLa.

[0069] When inserting the medical device 10, the expander 21 is retracted and stored in the storage sheath 25. The expander 21 can be exposed by moving the storage sheath 25 towards the proximal end from the state in which the storage sheath 25 has penetrated the atrial septum HA. When the expander 21 is exposed, it expands radially, and the recess 51 is positioned in the first opening Hh1 of the atrial septum HA, receiving the biological tissue surrounding the first opening Hh1 into the receiving space 24.

[0070] As shown in Figure 14, when the traction shaft 26 is moved towards the proximal end while the receiving space 24 is receiving biological tissue, the expander 21 is pulled in the compression direction by the tip member 35 and compressed axially, and the atrial septum HA is grasped by the proximal upright portion 52 and the tip upright portion 53 that form the recess 51, and the electrode portion 22 is pressed against the biological tissue. At this time, as the radial position of the recess 51 moves outward, the first opening Hh1 expands radially, and the second opening Hh2 is formed. The diameter of the second opening Hh2 is larger than that of the first opening Hh1. The fossa ovale, where the second opening Hh2 is formed, has less wall thickness than other parts of the atrial septum HA. For this reason, the recess 51 of the expander 21 can sandwich the biological tissue surrounding the second opening Hh2 so as to press the electrode portion 22 against the biological tissue.

[0071] With the electrode portion 22 pressed against the biological tissue, high-frequency energy can be applied through the electrode portion 22 to the edge of the second opening Hh2, that is, to the biological tissue surrounding the second opening Hh2, thereby cauterizing (heating and cauterizing) the edge of the second opening Hh2 with high-frequency energy. The high-frequency energy is applied by applying a voltage between a pair of circumferentially adjacent electrode portions 22. This prevents the communication hole Hh from closing due to natural healing and maintains its size. After cauterization, when the expander 21 is contracted and removed, the second opening Hh2 contracts slightly in the radial direction, and the communication hole Hh is formed.

[0072] When using the medical device 10, hemodynamic monitoring is performed by a hemodynamic monitoring device 120 delivered to the right atrium HRa via the inferior vena cava IV. For example, a known echocardiogram catheter can be used as the hemodynamic monitoring device 120. The operator can display the echocardiogram acquired by the hemodynamic monitoring device 120 on a display device such as a display, and confirm the amount of blood passing through the communication opening Hh based on the display results.

[0073] When removing the expandable body 21 after cauterization by the electrode portion 22, the storage sheath 25 is advanced relative to the shaft portion 20, and the expandable body 21 is pulled into the storage sheath 25 from the proximal end. At this time, the wiring portion 71, which is positioned inward from the linear body 50 of the expandable body 21 by the tip covering portion 27, is less likely to interfere with the contracting linear body 50, thus reducing the possibility of the wiring portion 71 being damaged by the linear body 50.

[0074] As described above, the medical device 10 according to this embodiment comprises a long shaft portion 20, an expandable body 21 connected to the tip of the shaft portion 20 and expandable and contractible in the radial direction, and at least one electrode assembly 70 having an electrode portion 22 for applying energy to biological tissue and extending elongatedly from the shaft portion 20 to the outside of the expandable body 21, wherein the expandable body 21 has a first through hole 61 through which at least one electrode assembly 70 is inserted from the inside to the outside of the expandable body 21, and a second locking portion 68 (locking portion) for locking at least one electrode assembly 70 so that the electrode portion 22 is positioned on the outside of the expandable body 21, the first through hole 61 has a maximum length L1 along a first extending direction X1 in which the outer surface of the expandable body 21 extends from the base end to the tip of the expandable body 21, and has a maximum width W1 along a first width direction Y1 perpendicular to the first extending direction X1. At least one electrode assembly 70 includes an electrode placement section 72 on which the electrode portion 22 is arranged, which includes a first end 79 in a second extending direction X2 in which the electrode assembly 70 extends, and a second end 80 on the opposite side of the first end 79 in the second extending direction X2, and a wiring section 71 which extends inside the extension 21 toward the shaft portion 20, which includes a first connecting section 76 connected to the first end 79 of the electrode placement section 72, and the electrode placement section 72 is perpendicular to the second extending direction X2. The electrode arrangement portion 72 has a maximum width W2 along the second width direction Y2, the first end 79 of the electrode arrangement portion 72 has a width W3 along the second width direction Y2, the first connecting portion 76 of the wiring portion 71 has a maximum width W4 along the second width direction Y2, and the maximum length L1 of the first through hole 61, the maximum width W1 of the first through hole 61, the maximum width W2 of the electrode arrangement portion 72, the width W3 of the first end 79 of the electrode portion 22, and the maximum width W4 of the first connecting portion 76 satisfy the following equation, L1 > W2 ≥ W3 > W1 > W4.

[0075] As a result, the medical device 10 can assemble the electrode assembly 70 to the expandable body 21 by adjusting the positional relationship between the electrode assembly 70 and the expandable body 21 so that the second width direction Y2 approaches the first extending direction X1, thereby passing the electrode placement section 72, which has a maximum width W2 along the second width direction Y2, through the first through hole 61, which has a maximum length L1 along the first extending direction X1. Furthermore, the first connecting section 76 of the wiring section 71, which has a maximum width W4, can be placed in the first through hole 61, which has a maximum width W1, and the first end 79 of the electrode placement section 72, which has a width W3, is prevented from passing through the first through hole 61, which has a maximum width W1, thereby preventing the electrode section 22 from being pulled inward from the first through hole 61 to the expandable body 21. Therefore, the medical device 10 can easily arrange the electrode section 22 from the inside to the outside of the expandable body 21 while preventing the electrode section 22 from falling out of the expandable body 21.

[0076] Furthermore, the first through-hole 61 has a first section 65 in which the maximum width W1 is formed, and a second section 66 that extends from the first section 65 along the first extending direction X1 and together with the first section 65 defines the maximum length L1 of the first through-hole 61, and the width W5 of the second section 66 along the first width direction Y1 is smaller than the maximum width W4 of the first connecting portion 76. As a result, the medical device 10 can position the first connecting portion 76 in the first section 65, and the electrode portion 22, which is positioned outside the expandable body 21, can be prevented from being pulled inside the expandable body 21 or shifted towards the second section 66, thus preventing displacement of the electrode portion 22.

[0077] Furthermore, the maximum distance L2 from the boundary edge of the second section 66 at the boundary with the first section 65 to the edge of the first section 65 on the opposite side of the boundary edge in the first extending direction X1 is narrower than the maximum width W4 of the first connecting portion 76. As a result, the first connecting portion 76, which is positioned in the first section 65, is prevented from rotating within the first section 65 so that the second width direction Y2 approaches the first extending direction X1. This prevents the first connecting portion 76 from shifting toward the second section 66 or from shifting toward the inside or outside of the expander 21. Therefore, the medical device 10 can better prevent displacement of the electrode portion 22, which is positioned outside the expander 21.

[0078] Furthermore, at least one electrode assembly 70 includes a second connecting portion 83 connected to the second end 80 of the electrode placement portion 72, and has an extending portion 73 that extends along the second extending direction X2, and the second locking portion 68 (locking portion) of the expansion body 21 locks the extending portion 73. As a result, the medical device 10 has a configuration in which the electrode portion 22 is not directly fixed to the expansion body 21, so problems such as the electrode portion 22 being damaged or the electrode portion 22 being covered with adhesive or the like for locking, which would prevent energy from being applied to biological tissue, can be prevented.

[0079] Furthermore, the expandable body 21 has a recess 51 that recesses radially inward when the expandable body 21 is expanded. The recess 51 has a bottom portion 56 located at the innermost radial end, a base-side upright portion 52 extending from the base end of the bottom portion 56 toward the radially outward base-side top portion 54, and a tip-side upright portion 53 extending from the tip of the bottom portion 56 toward the radially outward tip-side top portion 55. The first through hole 61 of the expandable body 21 is provided in the base-side upright portion 52 so that the electrode portion 22 is positioned along the base-side upright portion 52. The second locking portion 68 (locking portion) of the expandable body 21 locks the extended portion 73 at a position adjacent to the bottom portion 56 of the tip-side upright portion 53. As a result, the medical device 10 can position the electrode portion 22 along the base-side upright portion 52 in close proximity to the bottom portion 56 of the recess 51.

[0080] Furthermore, the tip-side upright portion 53 of the expanded body 21 has a second through-hole 64 adjacent to the bottom portion 56 through which the extended portion 73 is inserted from the inside to the outside of the expanded body 21, and the second locking portion 68 (locking portion) is formed from the edge of the second through-hole 64, and the extended portion 73 has an edge of the second through-hole 64 where the second locking portion 68 (locking portion) is formed at the end of the second connecting portion 83 opposite to the electrode arrangement portion 72 in the second extending direction X2, and the extended portion 73 has an edge of the second through-hole 64 where the second locking portion 68 (locking portion) is formed. The extension 73 has a second locking portion 85 that engages from the inside, the second through hole 64 has a maximum width W6 along the first width direction Y1, the second connecting portion 83 of the extension 73 has a maximum width W7 along the second width direction Y2, and the second locking portion 85 of the extension 73 has a maximum width W8 along the second width direction Y2, and the maximum width W6 of the second through hole 64, the maximum width W7 of the second connecting portion 83, and the maximum width W8 of the second locking portion 85 satisfy the following equation, W8 > W6 > W7. As a result, the second connecting portion 83 having a maximum width W7 can be positioned in the second through hole 64 having a maximum width W6, and the second locking portion 85 having a maximum width W8 is prevented from passing through the second through hole 64 having a maximum width W6, thereby preventing the extension 73 from being pulled out of the second through hole 64 to the outside of the extension 21. Therefore, the medical device 10 can easily and reliably lock the second locking portion 85 of the electrode assembly 70 to the second locking portion 68 (locking portion) of the expander 21.

[0081] Furthermore, the extension portion 73 includes an extension portion body 81 including a second connecting portion 83, two second projections 82 protruding from the connecting portion of the extension portion body 81 on both sides in the second width direction Y2, and a slit 84 provided between the two second projections 82 in the second width direction Y2. The width of the extension portion body 81 along the second width direction Y2 is smaller than the maximum width W6 of the second through hole 64. The second locking portion 85 includes two second projections 82, a portion of the extension portion body 81 positioned between the two second projections 82, and the slit 84. As a result, the extension portion 73 can be easily displaced by the slit 84 in a direction that brings the two second projections 82 closer to each other in the second width direction Y2, so that the second locking portion 85 can be easily passed through the second through hole 64 and the second locking portion 85 can be securely locked to the edge of the second through hole 64 from the inside of the extension body 21.

[0082] Furthermore, the second end 80 of the electrode placement portion 72 has a width W9 that is wider than the maximum width W6 of the second through hole 64 along the second width direction Y2. This prevents the electrode portion 22, which is positioned on the outside of the expandable body 21, from being pulled inward through the second through hole 64.

[0083] Furthermore, the wiring portion 71 has a first locking portion 78 at the end of the first connecting portion 76 opposite to the electrode arrangement portion 72 in the second extending direction X2, which engages with the edge of the first through hole 61 from the inside of the expansion body 21. The first locking portion 78 of the wiring portion 71 has a width W10 formed wider than the maximum width W1 of the first through hole 61 along the second width direction Y2. As a result, the medical device 10 makes it difficult for the wiring portion 71 of the electrode assembly 70 to be pulled out to the outside of the expansion body 21. Therefore, the medical device 10 can prevent the electrode portion 22 from shifting position, the electrode assembly 70 from bending significantly outside the expansion body 21 and damaging biological tissue, and the electrode assembly 70 itself from being damaged.

[0084] It should be noted that the present invention is not limited to the embodiments described above, and various modifications can be made by those skilled in the art within the technical framework of the present invention. For example, as shown in the modified example in Figure 15, the extension body 21 does not need to have a tip converging portion 57. The medical device 10 has at least one traction wire 101 that is pulled by operation of the handheld operating unit 23 instead of the traction shaft 26. The tip of the traction wire 101 is fixed to the tip-side upright portion 53. Therefore, when the traction wire 101 is pulled, the electrode portion 22 can be pressed against biological tissue.

[0085] This application is based on Japanese Patent Application No. 2024-169099, filed on September 27, 2024, and its disclosures are referenced and incorporated as a whole.

[0086] 10 Medical device 20 Shaft portion 21 Extension body 22 Electrode portion 51 Recess 52 Proximal end upright portion 53 Proximal end upright portion 54 Proximal end top portion 55 Proximal end top portion 56 Bottom portion 61 First through hole 64 Second through hole 65 First section 66 Second section 67 First locking portion 68 Second locking portion (locking portion) 70 Electrode assembly 71 Wiring portion 72 Electrode placement portion 73 Extension portion 76 First connecting portion 78 First locked portion 79 First end 80 Second end 81 Extension portion body 82 Second projection 83 Second connecting portion 84 Slit 85 Second locked portion X1 First extension direction X2 Second extension direction Y1 First width direction Y2 Second width direction

Claims

1. A medical device comprising: an elongated shaft portion; an expandable body connected to the tip of the shaft portion and expandable and contractible in the radial direction; and at least one electrode assembly having an electrode portion for applying energy to biological tissue, extending elongatedly from the shaft portion to the outside of the expandable body, wherein the expandable body has a first through-hole through which the at least one electrode assembly is inserted from the inside to the outside of the expandable body, and a locking portion for locking the at least one electrode assembly so that the electrode portion is positioned on the outside of the expandable body, the first through-hole having a maximum length L1 along a first extending direction in which the outer surface of the expandable body extends from the base end to the tip, and a maximum width W1 along a first width direction perpendicular to the first extending direction, The at least one electrode assembly comprises an electrode placement portion where the electrode portion is arranged, including a first end in a second extending direction in which the electrode assembly extends and a second end opposite to the first end in the second extending direction; and a wiring portion extending inside the extension toward the shaft portion, including a first connecting portion connected to the first end of the electrode placement portion, wherein the electrode placement portion has a maximum width W2 along a second width direction perpendicular to the second extending direction; the first end of the electrode placement portion has a width W3 along the second width direction; the first connecting portion of the wiring portion has a maximum width W4 along the second width direction; and the maximum length L1 of the first through hole, the maximum width W1 of the first through hole, the maximum width W2 of the electrode placement portion, the width W3 of the first end of the electrode portion, and the maximum width W4 of the first connecting portion satisfy the following equation: L1 > W2 ≥ W3 > W1 > W4.

2. The medical device according to claim 1, wherein the first through-hole has a first section in which the maximum width W1 is formed, and a second section extending from the first section along a first extending direction and together with the first section defining the maximum length L1 of the first through-hole, and the width W5 of the second section along the first width direction is smaller than the maximum width W4 of the first connecting portion.

3. The medical device according to claim 2, wherein the maximum distance L2 from the boundary edge at the boundary between the second section and the first section to the edge of the first section opposite to the boundary edge in the first extending direction is narrower than the maximum width W4 of the first connecting portion.

4. The medical device according to claim 1, wherein the at least one electrode assembly includes a second connecting portion connected to the second end of the electrode placement portion and has an extending portion extending along the second extending direction, and the locking portion of the extension body locks the extending portion.

5. The medical device according to claim 4, wherein the expandable body has a recess that is recessed radially inward when the expandable body is expanded, the recess has a bottom portion located radially inward, a base-side upright portion extending radially outward from the base end of the bottom portion toward the base-side top portion, and a tip-side upright portion extending radially outward from the tip of the bottom portion toward the tip-side top portion, the first through hole of the expandable body is provided in the base-side upright portion such that the electrode portion is positioned along the base-side upright portion, and the locking portion of the expandable body locks the extended portion at a position adjacent to the bottom portion of the tip-side upright portion.

6. The tip-side upright portion of the expandable body has a second through-hole at the position adjacent to the bottom portion through which the extended portion is inserted from the inside to the outside of the expandable body; the locking portion is formed from the edge of the second through-hole; the extended portion has a second locked portion at the end of the second connecting portion opposite to the electrode placement portion in the second extending direction, which engages from the inside of the expandable body with the edge of the second through-hole where the locking portion is formed; the second through-hole has a maximum width W6 along the first width direction; the second connecting portion of the extended portion has a maximum width W7 along the second width direction; the second locked portion of the extended portion has a maximum width W8 along the second width direction; and the maximum width W6 of the second through-hole, the maximum width W7 of the second connecting portion, and the maximum width W8 of the second locked portion satisfy the following equation: W8 > W6 > W7. The medical device according to claim 5.

7. The medical device according to claim 6, wherein the extending portion comprises an extending portion body including the second connecting portion, two second projections protruding from the second connecting portion of the extending portion body to both sides in the second width direction, and a slit provided between the two second projections in the second width direction, the width of the extending portion body along the second width direction being smaller than the maximum width W6 of the second through hole, and the second locking portion comprises the two second projections, the portion of the extending portion body disposed between the two second projections, and the slit.

8. The medical device according to claim 6 or 7, wherein the second end of the electrode arrangement portion has a width W9 formed wider than the maximum width W6 of the second through hole along the second width direction.

9. The medical device according to claims 1 to 7, wherein the wiring portion has a first locking portion at the end of the first connecting portion opposite to the electrode arrangement portion in the second extending direction, which engages with the edge of the first through hole from the inside of the extension body, and the first locking portion of the wiring portion has a width W10 formed wider than the maximum width W1 of the first through hole in the second width direction.

10. The medical device according to claim 9, wherein the wiring portion comprises a wiring portion body including the first connecting portion, and two first protrusions projecting from the connecting portion of the wiring portion body to both sides in the second width direction, the width of the extending portion body along the second width direction is smaller than the maximum width W1 of the first through hole, and the first locking portion is formed from the two first protrusions and a portion of the extending portion body disposed between the two first protrusions.

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