Medical device

Abstract

In order to provide a medical device capable of suppressing contact, during contraction of an expansion body, between linear bodies which are adjacent to each other in a circumferential direction, this medical device comprises: an expansion body (21) composed of a plurality of linear bodies (50) and capable of expanding and contracting in a radial direction; and a shaft part (20) connected to a proximal end of the expansion body. In the expansion body, the distance between the linear bodies adjacent to each other in the circumferential direction among the plurality of linear bodies changes in accordance with the expansion and contraction of the expansion body. The shaft part has a shaft body portion (30) having a connection section (31) for securing the proximal end of the expansion body, and a distal-end shaft portion (33) disposed on the distal-end side of the connection section and extending toward the inside of the expansion body. The distal-end shaft portion has a large diameter section (36) having a larger outer diameter than the outer diameter of the shaft body portion. The large diameter section is configured to make contact, in a contracted state of the expansion body, with an inner surface facing a center-axis side of the linear bodies constituting the expansion body.

Description

medical devices

[0001] The present invention relates to a medical device in which an expandable and contractible expander has a recess.

[0002] A medical device known in the art uses an electrode placed in an expandable body that expands and contracts within the body, and performs ablation treatment by cauterizing biological tissue with high-frequency current from the electrode. One known ablation treatment is atrial septal shunt therapy. Shunt therapy involves creating a shunt (a through-hole) in the fossa ovalis of the atrial septum, which serves as an escape route for elevated atrial pressure in patients with heart failure, thereby alleviating the symptoms of heart failure. In shunt therapy, the atrial septum is accessed via a transvenous approach, and a shunt of the desired size is created.

[0003] The expandable body has a recess that recesses radially inward when the expandable body is expanded, defining a receiving space capable of receiving biological tissue. The electrode portion is disposed in the recess. Furthermore, the shaft portion having the expandable body at its distal end has a traction portion that can traction the expandable body to change the shape and radial position of the recess. The traction portion deforms the recess, allowing the recess to sandwich biological tissue received in the receiving space from both sides in the thickness direction. Such a medical device is disclosed, for example, in Patent Document 1.

[0004] International Publication No. 2019-085841

[0005] The expandable body is formed of multiple linear bodies in the circumferential direction. When the medical device is inserted into a blood vessel, the expandable body is stored in a sheath and in a contracted state. By moving the sheath toward the base end relative to the expandable body, the expandable body becomes exposed at the distal end of the sheath and can be expanded. By moving the sheath toward the distal end relative to the expandable body from the exposed state, the expandable body can be pulled into the sheath and stored.

[0006] When the expanded expandable body is pulled into the sheath, the distance between adjacent linear bodies in the circumferential direction decreases as they are accommodated in the sheath. At this time, the adjacent linear bodies come into contact with each other in the circumferential direction, which can cause damage to the linear bodies or peeling off of the coating applied to their surfaces.

[0007] The present invention has been made to solve the above-mentioned problems, and aims to provide a medical device that can prevent circumferentially adjacent linear bodies from coming into contact with each other when the expansion body contracts.

[0008] (1) The medical device of the present invention, which achieves the above-mentioned object, comprises an expansion body consisting of a plurality of linear bodies, having a central axis, and capable of radially expanding and contracting between a contracted state and an expanded state, and a long, hollow shaft portion connected to the base end of the expansion body, wherein the expansion body is configured so that the distance between circumferentially adjacent linear bodies among the plurality of linear bodies changes according to the expansion and contraction of the expansion body, and the shaft portion comprises a shaft main body portion extending from a hand-operated operating portion provided at the base end toward the tip and having a connecting portion that fixes the base end of the expansion body, and a tip shaft portion positioned distal to the connecting portion and extending toward the interior of the expansion body, wherein the tip shaft portion has a large diameter portion having an outer diameter larger than the outer diameter of the shaft main body portion, and the large diameter portion contacts the inner surface facing the central axis of the linear bodies that constitute the expansion body when the expansion body is in the contracted state.

[0009] In the medical device (1) configured as described above, when the expansion body is contracted, the inner surface of the linear body comes into contact with the large diameter portion, and contact between adjacent linear bodies in the circumferential direction is suppressed, thereby preventing the linear body from being damaged or the coating applied to the surface of the linear body from peeling off.

[0010] (2) In the medical device of (1) above, the expandable body may have a recess that is recessed radially inward in the expanded state, the recess having a bottom portion located at the innermost radial position, a base-side upright portion extending from a base end of the bottom portion toward a base-side apex on the radially outer side, and a tip-side upright portion extending from a tip end of the bottom portion toward a tip-side apex on the radially outer side, and the large diameter portion may contact the inner surface of the linear body between the base-side apex and the tip end of the bottom portion in the contracted state of the expandable body. This allows the linear body to maintain a circumferential distance near the bottom portion, which has the smallest diameter, when the recess is contracted, by the large diameter portion, and prevents the linear bodies from contacting each other.

[0011] (3) In the medical device of (2), the medical device is used together with a sheath through which the shaft portion can be inserted and which can house the expandable body so that the expandable body is in the contracted state, and when the expandable body is housed in the sheath and in the contracted state, the proximal apex and the distal apex may be configured to contact the inner surface of the sheath, and the bottom may be configured to be separated from the inner surface of the sheath. This makes it easier to deform the recess when the expandable body is housed in the sheath.

[0012] (4) In the medical device of (2) or (3) above, the large-diameter portion may be located proximally of the bottom of the expandable body in the contracted state and distally of the base-side apex of the expandable body, and may contact the inner surface of the base-side upright portion at a portion where the outer diameter of the expandable body gradually decreases toward the bottom in the contracted state. This allows the large-diameter portion to maintain the spacing between the linear bodies at the base-side upright portion while not contacting the bottom, making it easier to deform the recess when storing the expandable body in the sheath.

[0013] (5) In any of the medical devices described in (1) to (4), the distal shaft portion may extend from the connecting portion of the shaft main body toward the distal end, and the large diameter portion may be disposed at the distal end of the distal shaft portion. This allows the distal shaft portion to be disposed at the proximal end portion of the expandable body, making it difficult for the proximal end portion of the expandable body to bend, and allowing the large diameter portion to be disposed in the central portion of the expandable body where the linear members of the expandable body are likely to come into contact with each other.

[0014] (6) In the medical device of any of (1) to (5) above, the large diameter portion may have outer peripheral convex portions along the circumferential direction, the same number as the number of the linear bodies in the large diameter portion, and the linear bodies may be arranged between the outer peripheral convex portions adjacent in the circumferential direction in the contracted state. This allows the medical device to arrange the linear bodies between the outer peripheral convex portions, and circumferential movement of the linear bodies is restricted, thereby further suppressing contact between the linear bodies.

[0015] (7) In the medical device of (6) above, the expandable body may have a distal inclined portion extending from the distal apex toward the distal end of the expandable body, and the distal end of the expandable body may have a converging portion where the plurality of linear bodies forming the distal inclined portion converge. This allows the large diameter portion to suppress contact between the linear bodies when the medical device has a shape that makes it easy for adjacent linear bodies to come close to each other in the circumferential direction.

[0016] (8) In any of the medical devices described in (2) to (4), the medical device may further include a traction shaft that is inserted into the shaft portion and is movable along the axial direction of the shaft portion, the traction shaft being exposed from the inside of the distal shaft portion to the outside, extending distally beyond the distal end of the expandable body, and moving proximally relative to the shaft portion to connect to the distal end of the expandable body, thereby compressing the expandable body in the axial direction and applying a traction force to the expandable body that changes the shape and radial position of the recess. This allows the medical device to suppress contact between the linear bodies in the expandable body, whose shape and radial position of the recess are changed by the traction shaft.

[0017] (9) In the medical device of (8) above, the distal shaft portion has a proximal rigid portion extending from the proximal end of the expansion body toward the interior of the expansion body, and a distal rigid portion extending from the distal end of the expansion body toward the interior of the expansion body, and the proximal rigid portion and the distal rigid portion are both more rigid than the traction shaft, and in the expanded state, the traction shaft is exposed to the outside between the proximal rigid portion and the distal rigid portion, and is configured to be connected to the distal end of the expansion body and to change the shape and radial position of the recess by pulling the distal rigid portion toward the proximal rigid portion, and in the expanded state, the distance between the proximal apex and the distal apex in the axial direction along the central axis may be approximately the same as the length along the axial direction of the traction shaft exposed between the proximal rigid portion and the distal rigid portion. As a result, when the traction shaft of the medical device is pulled, the rigid tip extension portion comes into contact with the tip rigid portion, thereby restricting further pulling and preventing damage to the expansion body due to strong contact between the base end apex and the tip end apex.

[0018] 1 is a front view showing the overall configuration of a medical device according to an embodiment; FIG. 1 is an enlarged perspective view of the vicinity of the expandable body of the medical device; FIG. 2 is an enlarged front view of the vicinity of the expandable body of the medical device; FIG. 3 is a perspective view of the vicinity of the distal end of the distal shaft portion; FIG. 4 is a cross-sectional view of the vicinity of the bottom of the expandable body, showing the positional relationship between the large diameter portion of the distal shaft portion and the linear body; FIG. 5 is an enlarged front view of the vicinity of the recess of the expandable body housed in the sheath; FIG. 6 is an enlarged perspective view of the sheath and the expandable body in a state in which the expandable body has been retracted into the sheath from the proximal upright portion to the portion toward the proximal end; FIG. 7 is an explanatory diagram schematically showing a state in which the expandable body is placed in the atrial septum, with the medical device in a front view and the biological tissue in a cross-sectional view; FIG. 8 is an enlarged front view of the vicinity of the distal end of the expandable body in the atrial septum, with the distal end side of the expandable body expanded in the atrial septum; FIG. 9 is an enlarged front view of the vicinity of the distal end of the expandable body in the atrial septum;

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the dimensional proportions in the drawings may be exaggerated for convenience of explanation and may differ from the actual proportions. In addition, in this specification, the side of the medical device 10 that is inserted into a body cavity will be referred to as the "distal end" or "distal side," and the side that is operated by the operator will be referred to as the "proximal end" or "proximal side."

[0020] The medical device in the following embodiments is configured to expand a through hole Hh formed in the atrial septum HA of a patient's heart H, and to perform a maintenance procedure to maintain the expanded through hole Hh at that size.

[0021] 1 and 2, the medical device 10 of this embodiment has a long, hollow shaft portion 20, an expansion body 21 provided at the distal end of the shaft portion 20, and a handheld operation portion 23 provided at the proximal end of the shaft portion 20. The expansion body 21 is provided with an electrode portion 22, which is an energy transmission element for performing the maintenance treatment described above. The expansion body 21 is formed of a linear body 50, and in its natural state when not subjected to external force, is in a radially expanded state due to its own expansion force.

[0022] The shaft portion 20 has a tubular shaft main body portion 30 extending from the hand operating portion 23 toward the tip, a connecting portion 31 that fixes the base end of the expansion body 21, and a tip shaft portion 33 that is positioned distal to the connecting portion 31.

[0023] The shaft portion 20 has a sheath 25 provided on the outermost periphery. The expansion body 21 is movable axially back and forth relative to the sheath 25. The sheath 25 can house the expansion body 21 inside when it is moved toward the distal end of the shaft portion 20. The expansion body 21 housed in the sheath 25 is in a contracted state. By moving the sheath 25 toward the proximal end from a state in which the expansion body 21 is housed, the expansion body 21 can be exposed to the outside and expanded.

[0024] A traction shaft 26 is disposed inside the shaft portion 20 as a traction portion so as to be slidable relative to the shaft portion 20. The traction shaft 26 is provided from the proximal end side of the hand operation portion 23 to the distal end side of the expansion body 21. The traction shaft 26 protrudes distally beyond the connecting portion 31 of the shaft portion 20, passes through the inside of the expansion body 21, and further protrudes from the distal end of the expansion body 21. The distal end of the traction shaft 26 is fixed to a distal member 38.

[0025] The tip member 38, to which the tip of the traction shaft 26 is fixed, is not fixed to the expansion body 21. As a result, the traction shaft 26 slides axially relative to the shaft portion 20 toward the proximal end, and the tip member 38 can thereby apply a compressive force to the expansion body 21 along the axial center of the shaft portion 20. Furthermore, when storing the expansion body 21 in the sheath 25, moving the tip member 38 away from the expansion body 21 toward the tip side facilitates movement of the expansion body 21 in the extension direction, improving storage ease.

[0026] The handheld operation unit 23 has a housing 40 that is held by the surgeon, an operation dial 41 that can be rotated by the surgeon, and a conversion mechanism 42 that operates in conjunction with the rotation of the operation dial 41. The traction shaft 26 is held by the conversion mechanism 42 inside the handheld operation unit 23. The conversion mechanism 42 can move the held traction shaft 26 forward and backward along the axial direction in accordance with the rotation of the operation dial 41. As the conversion mechanism 42, for example, a rack and pinion mechanism can be used.

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

[0028] The traction shaft 26 can be formed of a long linear body made of, for example, a superelastic alloy such as a nickel-titanium alloy or a copper-zinc alloy, a metal material such as stainless steel, or a resin material with relatively high rigidity.

[0029] The tip member 38 can be formed, for example, from a superelastic alloy such as a nickel-titanium alloy or a copper-zinc alloy, a metal material such as stainless steel, a polymer material such as polyolefin, polyvinyl chloride, polyamide, polyamide elastomer, polyurethane, polyurethane elastomer, polyimide, or fluororesin, or a mixture of these, or a multi-layer tube made of two or more types of polymer materials.

[0030] The distal shaft portion 33 has a proximal rigid portion 34 extending from the proximal end of the expansion body 21 toward the inside of the expansion body 21, and a distal rigid portion 35 extending from the distal end of the expansion body 21 toward the inside of the expansion body 21. The proximal rigid portion 34 and the distal rigid portion 35 constituting the shaft portion 20 are both more rigid than the traction shaft 26.

[0031] The proximal rigid portion 34 extends along the central axis of the expandable body 21 from the proximal end of the expandable body 21 to partway along the expandable body 21. When the expandable body 21 is in a radially expanded state, the distal end position A1 of the proximal rigid portion 34 in the longitudinal direction is located distal to the bottom 51 a of the recess 51.

[0032] The traction shaft 26 is inserted through the proximal rigid portion 34 and distal rigid portion 35 that constitute the distal shaft portion 33 and protrudes from the distal end of the distal rigid portion 35. The portion of the traction shaft 26 between the distal shaft portion 33 and the distal rigid portion 35 is exposed to the outside. Because the expandable body 21 has the distal rigid portion 35, when the biological tissue around the puncture hole Hh has a thickness that varies in the circumferential direction, the traction shaft 26 can bend in accordance with the thickness of the biological tissue, and the recess 51 of the expandable body 21 can be in close contact with the biological tissue over the entire circumferential direction. Furthermore, in the expandable body 21, the distance L1 between the proximal apex 51c and the distal apex 51d in the axial direction along the central axis is approximately the same as the length L2 along the axial direction of the traction shaft 26 that is exposed between the proximal rigid portion 34 and the distal rigid portion 35.

[0033] The expandable body 21 has multiple linear bodies 50 in the circumferential direction. The linear bodies 50 branch and merge along the length direction to form a mesh-like structure. This allows the expandable body 21 to expand and contract in the radial direction. The distance between adjacent linear bodies 50 in the circumferential direction changes as the expandable body 21 expands and contracts. When the expandable body 21 is in an expanded state, the distance between adjacent linear bodies 50 in the circumferential direction is large. When the expandable body 21 contracts, the distance between adjacent linear bodies 50 in the circumferential direction becomes smaller.

[0034] The base end of linear body 50 extends toward the tip end from base end convergence portion 57. The tip end of linear body 50 extends toward the base end from tip end convergence portion 58. When expandable body 21 is in an expanded state, linear body 50 has base end inclined portion 55 that is inclined so as to increase radially from base end convergence portion 57 toward the center, and tip end inclined portion 56 that is inclined so as to increase radially from tip end convergence portion 58 toward the center.

[0035] The linear body 50 has a recess 51 in its axial center, recessed radially inward of the expandable body 21 in its expanded state. The radially innermost portion of the recess 51 is a bottom 51a. The recess 51 has a base-side upright portion 51e extending from the base end of the bottom 51a to a base-side apex 51c on the radially outer side, and a distal-side upright portion 51f extending from the tip of the bottom 51a to a distal-side apex 51d on the radially outer side. The bottom 51a is the range where the linear body 50 bends radially innermost in the extension direction of the linear body 50, and the base-side upright portion 51e and the distal-side upright portion 51f are the range where the linear body 50 extends linearly in the extension direction of the linear body 50. The recess 51 defines a receiving space 51b that can receive biological tissue when the expandable body 21 is expanded.

[0036] When the traction shaft 26 slides relative to the shaft portion 20 in the proximal direction and a compressive force is applied to the expansion body 21, the distal upright portion 51f and the proximal upright portion 51e approach each other and come into close contact with the biological tissue received in the receiving space 51b. The proximal upright portion 51e has an electrode portion 22 arranged along the recess 51 so as to face the receiving space 51b. That is, the electrode portion 22 is provided along the expansion body 21 at a middle portion in the central axial direction of the expansion body 21. In this embodiment, ten electrode portions 22 are provided along the circumferential direction. The electrode portion 22 may also be arranged on the distal upright portion 51f.

[0037] The linear body 50 that forms the expandable 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 metal material. Examples of such metal materials that can be used 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 a superelastic alloy such as a nickel-titanium alloy so that the expandable body 21 can self-expand from a contracted state to its natural radially expanded state. However, the material of the linear body 50 is not limited to these, and other materials may also be used.

[0038] The electrode unit 22 is connected to an external energy supply device (not shown). A high-frequency voltage is applied from the energy supply device to an electrode pair consisting of two electrode units 22, and energy is imparted between them. In other words, the electrode unit 22 is configured as a bipolar electrode. However, the electrode unit 22 may also be a monopolar electrode. In this case, electricity is passed between the electrode unit 22 and an external electrode.

[0039] 2 and 3, the distal shaft portion 33 has a large-diameter portion 36 at the distal end of the proximal rigid portion 34, the large-diameter portion 36 having an outer diameter larger than the outer diameter of the shaft main body 30. As shown in FIG. 4, the large-diameter portion 36 is formed by expanding the diameter of the distal end portion of the proximal rigid portion 34 constituting the distal shaft portion 33 more than the proximal end portion. As an example, when the outer diameter of the shaft main body 30 is 2.8 mm, the outer diameter of the large-diameter portion 36 can be 3.0 to 3.6 mm. However, the outer diameter of the large-diameter portion 36 may be outside this range.

[0040] As shown in Figure 5, if the outer diameter of the large diameter portion 36 is D, the circumference of the outer surface of the large diameter portion 36 is πD. The inner surface of each linear body 50 facing the central axis has a width w, and ten linear bodies 50 are arranged in the circumferential direction. In this case, the circumference πD of the outer surface of the large diameter portion 36 is greater than 10w, which is the total width of the ten linear bodies 50. Therefore, when the expandable body 21 is in a contracted state, the large diameter portion 36 comes into contact with the inner surface of each linear body 50 facing the central axis, and a gap of distance t is formed between adjacent linear bodies 50 in the circumferential direction. In other words, the relationship πD = 10w + 10t holds.

[0041] The large diameter portion 36 of the distal shaft portion 33 comes into contact with the inner surfaces of the linear members 50 constituting the expandable body 21 in the contracted state, from the base-side apex 51c to the tip of the bottom portion 51a. The large diameter portion 36 has a length in the central axis direction necessary to prevent the linear members 50 near the bottom portion 51a from coming into contact with each other in the contracted expandable body 21. Meanwhile, the base end of the large diameter portion 36 is located distal to the base-side apex 51c of the expandable body 21 so as not to increase the maximum diameter of the expandable body 21 in the contracted state.

[0042] As shown in Fig. 6, the expandable body 21 housed inside the sheath 25 is in a contracted state. In this state, the distal end position A2 of the proximal rigid portion 34 in the longitudinal direction is located near the bottom 51a of the expandable body 21. More specifically, when the expandable body 21 is contracted, the distal end position A2 of the proximal rigid portion 34 in the longitudinal direction is located closer to the proximal end than the radially innermost position of the bottom 51a, and contacts the inner surface of the expandable body 21 between the proximal apex 51c and the tip of the bottom 51a. If the distal end position A2 of the proximal rigid portion 34 in the longitudinal direction is located near the bottom 51a when the expandable body 21 is contracted, then when the expandable body 21 is expanded, the distal end position A1 of the proximal rigid portion 34 in the longitudinal direction is located closer to the distal end of the bottom 51a and closer to the proximal end than the tip of the expandable body 21, as shown in Fig. 3. When the expandable body 21 is expanded, the distal end position A1 of the proximal rigid portion 34 in the longitudinal direction is located distal to the bottom portion 51a, and therefore an axis extending from the proximal end of the expandable body 21, past the bottom portion 51a, to the distal end exists inside the expandable body 21. This makes it difficult for the expanded expandable body 21 to bend on the proximal side relative to the bottom portion 51a, and the electrode portion 22 arranged along the proximal upright portion 51e can be reliably pressed against biological tissue.

[0043] When the expandable body 21 is contracted, the tip position A2 in the longitudinal direction of the proximal rigid portion 34 only needs to be located near the bottom 51a, and may be located within the range of the bottom 51a or within the range of the proximal upright portion 51e in the extension direction of the linear body 50. The tip position A2 in the longitudinal direction of the proximal rigid portion 34 may be located at the boundary between the bottom 51a and the proximal upright portion 51e in the extension direction of the linear body 50.

[0044] The large diameter portion 36 of the distal shaft portion 33 contacts the inner surface of the linear bodies 50 constituting the expansion body 21 in the contracted state, from the base end apex 51c to the tip of the bottom portion 51a, forming a gap between adjacent linear bodies 50 in the circumferential direction, thereby preventing the linear bodies 50 from contacting each other in the contracted state.

[0045] As shown in FIG. 7 , when the expanded expandable body 21 is retracted into the sheath 25 from the proximal end to the proximal-side upright portion 51e, the inner surface of the linear body 50 contacts the large-diameter portion 36 of the distal shaft portion 33, forming a gap of distance t between adjacent linear bodies 50 in the circumferential direction. This prevents the linear bodies 50 from contacting each other when the expandable body 21 is retracted into the sheath 25. By preventing the linear bodies 50 from contacting each other, the medical device 10 can prevent friction between the linear bodies 50 and prevent peeling of the coating applied to the surface of the linear body 50. The function of the coating is to provide the linear body 50 with insulating properties, slidable properties, or both. The insulating properties of the coating prevent the high-frequency current flowing through the electrode portion 22 from flowing through the linear body 50, which could damage the medical device 10, or the linear body 50 from overheating and causing thrombus formation. Furthermore, the coating has slidability, which reduces the resistance when the expandable body 21 is retracted into the sheath 25, etc., thereby reducing the risk of breakage of the linear body 50 and improving operability. Examples of materials for this coating include parylene, polytetrafluoroethylene (PTFE), and silicone resin. In terms of the stability and durability of the formed coating and the ability to follow the deformation of the linear body 50, a coating in which parylene is vapor-deposited onto the linear body 50 is preferred.

[0046] 6 , when the expandable body 21 is housed in the sheath 25 and in a housed state, the proximal apex 51c and the distal apex 51d contact the inner surface of the sheath 25, and the bottom 51a is separated from the inner surface of the sheath 25. At this time, the tip of the proximal rigid portion 34 contacts the inner surface of the proximal upright portion 51e at a location where the outer diameter of the expandable body 21 gradually decreases toward the bottom 51a. In other words, the proximal rigid portion 34 is not located inside the bottom 51a, where the expandable body 21 is located at the innermost radial position. This makes it easy to contract the expandable body 21 and store it.

[0047] When using the medical device 10, a through-hole Hh is first formed at the position of the fossa ovalis in the atrial septum HA using a puncture device. The medical device 10 performs a procedure to expand the through-hole Hh and cauterize the edges of the through-hole Hh, thereby maintaining the expanded through-hole Hh at its original size. As shown in Fig. 8 , 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 sheath 25 is inserted up to the atrial septum HA so that the expandable body 21 is positioned at the position of the pre-formed through-hole Hh. The distal end of the sheath 25 penetrates the atrial septum HA and reaches the left atrium HLa.

[0048] When the medical device 10 is inserted, the expandable body 21 is housed in the sheath 25 and is in a contracted state. When the sheath 25 has penetrated the atrial septum HA, the sheath 25 is moved proximally, thereby exposing and expanding the portion of the expandable body 21 distal to the recess 51, as shown in Fig. 9. Even if a twisting force acts on the expandable body 21 when the medical device 10 is inserted, twisting of the expandable body 21 is suppressed because the distal shaft portion 33 extends to the vicinity of the bottom 51a of the recess 51, and poor deployment of the expandable body 21 due to twisting can be suppressed.

[0049] When the sheath 25 is moved further toward the base end and the entire expandable body 21 is exposed, the portion of the expandable body 21 that is proximal to the recess 51 also expands radially, and the recess 51 is positioned in the through hole Hh in the atrial septum HA, and the receiving space 51b receives the biological tissue surrounding the through hole Hh.

[0050] As shown in FIG. 10 , by moving the traction shaft 26 toward the proximal end while the receiving space 51b accommodates the biological tissue, the expandable body 21 is pulled in the compression direction by the distal member 38 and compressed in the axial direction. The atrial septum HA is grasped by the proximal upright portion 51e and the distal upright portion 51f that form the recess 51, and the electrode portion 22 is pressed against the biological tissue. The fossa ovalis, where the through-hole Hh is formed, has a smaller wall thickness than other parts of the atrial septum HA. Therefore, the recess 51 of the expandable body 21 can clamp the biological tissue by squeezing it. At this time, the distal end of the proximal rigid portion 34 and the proximal end of the distal rigid portion 35 are close to each other. The distal position of the proximal rigid portion 34 in the longitudinal direction is set so that it does not extend beyond the bottom portion 51a toward the distal end when the expandable body 21 is contracted, so as not to interfere with the proximal end of the distal rigid portion 35 when the expandable body 21 is clamped against the biological tissue.

[0051] With the electrode portion 22 pressed against the biological tissue, the edge of the through-hole Hh can be cauterized (heated and cauterized) by the high-frequency energy by applying high-frequency energy to the edge of the through-hole Hh through the electrode portion 22. The high-frequency energy is applied by applying a voltage between a pair of circumferentially adjacent electrode portions 22. This inhibits the through-hole Hh from closing due to natural healing and maintains its size.

[0052] When the medical device 10 is in use, hemodynamics is confirmed by the hemodynamic confirmation device 120 delivered to the right atrium HRa via the inferior vena cava Iv. A known echo catheter, for example, can be used as the hemodynamic confirmation device 120. The surgeon can display the echo image acquired by the hemodynamic confirmation device 120 on a display or other display device, and can confirm the amount of blood passing through the through-hole Hh based on the displayed image.

[0053] After performing treatment using the electrode portion 22, the surgeon moves the sheath 25 toward the distal end to store the expandable body 21. During this process, as shown in Figure 7, the large diameter portion 36 ensures a gap between adjacent linear bodies 50 in the circumferential direction, thereby preventing damage to the linear bodies 50 and peeling of the coating applied to the surface of the linear bodies 50.

[0054] 11 , the large diameter portion 36 of the distal end shaft portion 33 may have multiple outer circumferential protrusions 37 along the circumferential direction of the outer circumferential surface. The outer circumferential protrusions 37 extend in the axial direction of the distal end shaft portion 33, and the number of outer circumferential protrusions 37 is the same as the number of linear bodies 50 in the circumferential direction in the large diameter portion 36. The linear bodies 50 in the contracted expandable body 21 are disposed between the outer circumferential protrusions 37 that are adjacent in the circumferential direction. The outer circumferential protrusions 37 restrict the linear bodies 50 from moving in the circumferential direction, further reducing contact between the linear bodies 50.

[0055] 12 , the distal shaft portion 33, which is disposed distally of the connecting portion 31, may have a proximal rigid portion 34 that extends short and a distal rigid portion 35 that extends long toward the interior of the expandable body 21, with a large diameter portion 39 formed at the proximal end of the distal rigid portion 35. The proximal position of the large diameter portion 39 is located proximally closer to the bottom 51 a of the recess 51 and can come into contact with the inner surface of the linear body 50 when the expandable body 21 is contracted.

[0056] As described above, the medical device 10 according to this embodiment (1) comprises an expansion body 21 consisting of a plurality of linear bodies 50, having a central axis, and capable of radially expanding and contracting between a contracted state and an expanded state, and a long, hollow shaft portion 20 connected to the base end of the expansion body 21, wherein the expansion body 21 is configured such that the distance between circumferentially adjacent linear bodies 50 among the plurality of linear bodies 50 changes according to the expansion and contraction of the expansion body 21, and the shaft portion 20 comprises a shaft main body 30 extending from a hand-operated operating unit 23 provided at the base end toward the tip and having a connecting portion 31 that fixes the base end of the expansion body 21, and a tip shaft portion 33 positioned distal to the connecting portion 31 and extending toward the interior of the expansion body 21, wherein the tip shaft portion 33 has a large diameter portion 36 having an outer diameter larger than the outer diameter of the shaft main body 30, and the large diameter portion 36 comes into contact with the inner surface facing the central axis of the linear bodies 50 that constitute the expansion body 21 when the expansion body 21 is in the contracted state. In the medical device 10 configured in this manner, when the expansion body 21 is contracted, the inner surface of the linear body 50 comes into contact with the large diameter portion 36, and contact between adjacent linear bodies 50 in the circumferential direction is suppressed, thereby preventing the linear body 50 from being damaged or the coating applied to the surface of the linear body 50 from peeling off.

[0057] (2) In the medical device 10 described in (1) above, the expandable body 21 has a recess 51 that is recessed radially inward in the expanded state, and the recess 51 has a bottom 51a located at the innermost radial position, a base-side upright portion 51e extending from the base end of the bottom 51a toward a base-side apex 51c on the radially outer side, and a tip-side upright portion 51f extending from the tip of the bottom 51a toward a tip-side apex 51d on the radially outer side, and the large-diameter portion 36 may contact the inner surface of the linear body 50 between the base-side apex 51c and the tip of the bottom 51a in the contracted state of the expandable body 21. As a result, in the medical device 10, the large-diameter portion 36 can ensure circumferential spacing between the linear bodies 50 near the bottom 51a, which has the smallest diameter, when the recess 51 is contracted, and contact between the linear bodies 50 can be suppressed.

[0058] (3) In the medical device 10 described in (2) above, the medical device 10 is used together with a sheath 25 through which the shaft portion 20 can be inserted and which can house the expansion body 21 so that the expansion body 21 is in a contracted state, and when the expansion body 21 is housed in the sheath 25 and in a contracted state, the base end apex 51 c and the tip end apex 51 d may be configured to contact the inner surface of the sheath 25, and the bottom 51 a may be configured to be separated from the inner surface of the sheath 25. This allows the medical device 10 to easily deform the recess 51 when the expansion body 21 is housed in the sheath 25.

[0059] (4) In the medical device 10 described in (2) or (3) above, the large-diameter portion 36 may be located proximally relative to the bottom 51a of the expandable body 21 in the contracted state and distally relative to the proximal apex 51c of the expandable body 21, and may be in contact with the inner surface of the proximal upright portion 51e at a location where the outer diameter of the expandable body 21 gradually decreases toward the bottom 51a in the contracted state. This allows the large-diameter portion 36 of the medical device 10 to maintain spacing between the linear bodies 50 at the proximal upright portion 51e while not contacting the bottom 51a, making it easier to deform the recess 51 when storing the expandable body 21 in the sheath 25.

[0060] (5) In any of the medical devices 10 described above in (1) to (4), the distal shaft portion 33 may extend from the connecting portion 31 of the shaft main body 30 toward the distal end, and the large diameter portion 36 may be located at the distal end of the distal shaft portion 33. In this way, the distal shaft portion 33 of the medical device 10 is located at the proximal portion of the expansion body 21, making it possible to make the proximal portion of the expansion body 21 less prone to bending, and to locate the large diameter portion 36 in the central portion of the expansion body 21 where the linear bodies 50 of the expansion body 21 are more likely to come into contact with each other.

[0061] (6) In the medical device 10 of any of (1) to (5) above, the large diameter portion 36 may have outer peripheral convex portions 37 along the circumferential direction, the same number as the number of linear bodies 50 in the large diameter portion 36, and the linear bodies 50 may be arranged, in the contracted state, between circumferentially adjacent outer peripheral convex portions 37. This allows the medical device 10 to arrange the linear bodies 50 between the outer peripheral convex portions 37, and circumferential movement of the linear bodies 50 is restricted, thereby further suppressing contact between the linear bodies 50.

[0062] (7) In the medical device 10 described in (6) above, the expandable body 21 may have a distal inclined portion 56 extending from the distal apex 51d toward the distal end of the expandable body 21, and the distal end of the expandable body 21 may have a converging portion 58 where the multiple linear bodies 50 forming the distal inclined portion 56 converge. This allows the large diameter portion 36 to suppress contact between the linear bodies 50 when the medical device 10 has a shape that makes it easy for adjacent linear bodies 50 to come close to each other in the circumferential direction.

[0063] (8) The medical device 10 of any of (2) to (4) above may have a traction shaft 26 that is inserted into the shaft portion 20 and is movable along the axial direction of the shaft portion 20, the traction shaft 26 being exposed from the inside of the distal shaft portion 33 to the outside, extending from the distal end of the expandable body 21 to the distal side, and moving in the proximal direction relative to the shaft portion 20, thereby connecting to the distal end of the expandable body 21 and compressing the expandable body 21 in the axial direction, and applying a traction force to the expandable body 21 that changes the shape and radial position of the recesses 51. In this way, the medical device 10 can suppress contact between the linear bodies 50 in the expandable body 21, in which the shape and radial position of the recesses 51 are changed by the traction shaft 26.

[0064] (9) In the medical device 10 described in (8) above, the distal shaft portion 33 has a proximal rigid portion 34 extending from the proximal end of the expansion body 21 toward the interior of the expansion body 21, and a distal rigid portion 35 extending from the distal end of the expansion body 21 toward the interior of the expansion body 21, and the proximal rigid portion 34 and the distal rigid portion 35 are both more rigid than the traction shaft 26, and in the expanded state, the traction shaft 26 is exposed to the outside between the proximal rigid portion 34 and the distal rigid portion 35, and is configured to be connected to the distal end of the expansion body 21 and pull the distal rigid portion 35 toward the proximal rigid portion 34 to change the shape and radial position of the recess 51, and in the expanded state, the distance between the proximal apex 51c and the distal apex 51d in the axial direction along the central axis may be approximately the same as the length along the axial direction of the traction shaft 26 exposed between the proximal rigid portion 34 and the distal rigid portion 35. As a result, when the traction shaft 26 of the medical device 10 is pulled, the rigid tip extension portion comes into contact with the tip rigid portion 35, thereby restricting further pulling and preventing damage to the expansion body 21 due to strong contact between the base end apex 51c and the tip end apex 51d.

[0065] The present invention is not limited to the above-described embodiment, and various modifications may be made by those skilled in the art within the technical spirit of the present invention. In the above-described embodiment, the traction portion is the traction shaft 26, but the traction portion may be another mechanism, such as a wire connected to the bottom 51a of the recess 51. Furthermore, the expandable body 21 does not need to have a recess, and the large-diameter portion 36 may contact the inner surface of the linear body 50 at any position on the expandable body 21.

[0066] In the above-described embodiment, the large diameter portion 36 is formed so that the tip portion is larger in diameter than the base end portion of the tip shaft portion 33, but the large diameter portion may also be formed by covering the tip portion of the tip shaft portion 33, which has a constant outer diameter, with a tubular member.

[0067] This application is based on Japanese Patent Application No. 2024-21847 filed on February 16, 2024, the disclosures of which are incorporated herein by reference in their entirety.

[0068] REFERENCE SIGNS LIST 10 Medical device 11 Guide wire 20 Shaft portion 21 Expansion body 22 Electrode portion 23 Proximal operation portion 25 Sheath 26 Traction shaft (traction portion) 30 Shaft main body 31 Connecting portion 33 Distal shaft portion 34 Proximal rigid portion 35 Distal rigid portion 36 Large diameter portion 37 Outer peripheral convex portion 38 Distal member 39 Large diameter portion 40 Housing 50 Linear body 51 Recess 51a Bottom 51b Receiving space 51c Proximal apex 51d Distal apex 51e Proximal upright portion 51f Distal upright portion 55 Proximal inclined portion 56 Distal inclined portion 57 Proximal convergent portion 58 Distal convergent portion

Claims

1. A medical device comprising: an expansion body consisting of a plurality of linear bodies, having a central axis, and capable of radially expanding and contracting between a contracted state and an expanded state; and a long, hollow shaft portion connected to the base end of the expansion body, wherein the expansion body is configured so that the distance between circumferentially adjacent linear bodies among the plurality of linear bodies changes in accordance with the expansion and contraction of the expansion body, and the shaft portion comprises: a shaft main body portion extending from a hand-operated operating portion provided at the base end toward the tip and having a connecting portion that fixes the base end of the expansion body; and a tip shaft portion positioned distal to the connecting portion and extending toward the interior of the expansion body, wherein the tip shaft portion has a large diameter portion having an outer diameter larger than the outer diameter of the shaft main body, and the large diameter portion comes into contact with the inner surface facing the central axis of the linear bodies that constitute the expansion body when the expansion body is in the contracted state.

2. The medical device of claim 1, wherein the expandable body has a recess that is recessed radially inward in the expanded state, the recess having a bottom portion located at the innermost radial position, a base-side upright portion extending from the base end of the bottom portion toward the base-side apex radially outward, and a tip-side upright portion extending from the tip of the bottom portion toward the tip-side apex radially outward, and the large diameter portion contacts the inner surface of the linear body between the base-side apex and the tip of the bottom portion when the expandable body is in a contracted state.

3. The medical device according to claim 2, wherein the medical device is used together with a sheath through which the shaft portion can be inserted and which can store the expansion body so that the expansion body is in the contracted state, and when the expansion body is stored in the sheath and in the contracted state, the base end apex and the tip end apex come into contact with the inner surface of the sheath, and the bottom is configured to be spaced apart from the inner surface of the sheath.

4. A medical device as described in claim 3, wherein the large diameter portion is located proximal to the bottom of the expandable body in the contracted state and distal to the base-side apex of the expandable body, and in the contracted state, contacts the inner surface of the base-side upright portion at a point where the outer diameter of the expandable body gradually decreases toward the bottom.

5. A medical device according to any one of claims 1 to 4, wherein the distal shaft portion extends from the connecting portion of the shaft main body portion toward the distal end, and the large diameter portion is located at the distal end of the distal shaft portion.

6. A medical device according to any one of claims 1 to 4, wherein the large diameter portion has outer peripheral convex portions along the circumferential direction, the number of which is the same as the number of the linear bodies in the large diameter portion, and the linear bodies are arranged between the outer peripheral convex portions adjacent to each other in the circumferential direction in the contracted state.

7. A medical device according to any one of claims 2 to 4, wherein the expandable body has a tip-side inclined portion extending from the tip-side apex toward the tip end of the expandable body, and the tip end of the expandable body has a converging portion where the multiple linear bodies forming the tip-side inclined portion converge.

8. A medical device according to any one of claims 2 to 4, comprising a traction shaft inserted into the shaft portion and movable along the axial direction of the shaft portion, the traction shaft being exposed from the inside of the tip shaft portion to the outside, extending beyond the tip of the expansion body to the distal side, and moving in the proximal direction relative to the shaft portion, thereby connecting to the distal end of the expansion body and compressing the expansion body in the axial direction, and applying a traction force to the expansion body that changes the shape and radial position of the recess.

9. The medical device of claim 8, wherein the distal shaft portion has a proximal rigid portion extending from the proximal end of the expansion body toward the interior of the expansion body, and a distal rigid portion extending from the distal end of the expansion body toward the interior of the expansion body, wherein the proximal rigid portion and the distal rigid portion are both more rigid than the traction shaft, wherein in the expanded state, the traction shaft is exposed to the outside between the proximal rigid portion and the distal rigid portion, and is configured to be connected to the distal end of the expansion body and to change the shape and radial position of the recess by pulling the distal rigid portion toward the proximal rigid portion, and wherein in the expanded state, the distance between the proximal apex and the distal apex in the axial direction along the central axis is approximately the same as the length along the axial direction of the traction shaft exposed between the proximal rigid portion and the distal rigid portion.

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