Method for manufacturing expandable body, method for manufacturing expandable body assembly, and medical device

Abstract

To provide a method for manufacturing an expandable body, a method for manufacturing an expandable body assembly, and a medical device, with which it is possible to suppress breakage of an expandable body during manufacture.　Provided is a method for manufacturing an expandable body (21) having a waist part (55) formed by a plurality of struts (50) that extend along the axial direction and that are arranged side-by-side in the circumferential direction surrounding the axial direction, the waist part (55) having an outside diameter that decreases partway along the axial direction, wherein in order to form a bottom part (56) having the smallest outside diameter of the waist part (55) and a standing part extending radially outward from the bottom part (56), the inside of a cylindrical base material (180) in which the plurality of struts (50) are formed is expanded by an inner mold, and the outside of the base material (180) is restricted by an outer mold (150).

Description

Manufacturing method of expandable body, manufacturing method of expandable body assembly, and medical device

[0001] The present invention relates to a method for manufacturing an expandable body, a method for manufacturing an expandable body assembly, and a medical device.

[0002] In order to expand a through-hole in a medical biological lumen or biological membrane, an expandable body made of a shape memory alloy is used, which can be inserted into the body in a contracted state and can expand in diameter within the body (see, for example, Patent Document 1).

[0003] Generally, to make an expandable body made of a shape memory alloy remember its shape, it is heat-treated while it is shaped in a mold.Expandable bodies used for medical purposes to expand through-holes in biological lumens or biological membranes are manufactured by inserting an inner mold into a tubular material processed with a laser processing machine or a mesh-like tubular body made by weaving multiple wires, and then expanding the diameter from the tubular shape.

[0004] International Publication No. 2019-085841

[0005] If the target expandable body has a waist portion where the outer diameter decreases suddenly like a constricted portion, attempting to achieve that shape through a single deformation will result in large strain and increase the risk of breakage.

[0006] The present invention has been made to solve the above-mentioned problems, and aims to provide a method for manufacturing an expandable body, a method for manufacturing an expandable body assembly, and a medical device that can suppress damage to the expandable body during manufacturing.

[0007] (1) A method for manufacturing an expandable body according to the present invention, which achieves the above-mentioned object, is a method for manufacturing an expandable body formed by a plurality of struts extending along an axial direction and arranged circumferentially surrounding the axial direction, and having a waist portion whose outer diameter decreases midway in the axial direction, and is characterized in that, in order to form a bottom portion having the smallest outer diameter of the waist portion and an upright portion extending radially outward from the bottom portion, the inside of a cylindrical base material on which the plurality of struts are formed is expanded with an inner mold, and the outside of the base material is restricted with an outer mold.

[0008] The manufacturing method of the expandable body described in (1) above forms the bottom and upright portion of the waist portion using an inner mold and an outer mold, thereby reducing distortion that occurs in the expandable body due to sudden deformation during manufacturing and suppressing damage to the expandable body.

[0009] (2) In the method for manufacturing an expandable body described in (1) above, the inner mold may include a first inner mold, and the manufacturing method may include a first step of forming one side of the expandable body located on one side of the bottom in the axial direction using the first inner mold and the outer mold together with the bottom, and a second step of forming the other side of the expandable body located on the opposite side to the one side. In this way, the manufacturing method for the expandable body forms the two halves in separate steps, thereby reducing distortion occurring in the expandable body and suppressing breakage of the expandable body.

[0010] (3) In the method for manufacturing an expandable body described in (2) above, in the first step and the second step, the outer mold may be covered with a ring-shaped outer mold that is not a split mold on the outside of the base material into which the first inner mold is inserted. If the outer mold is a split mold, repeated use may cause different deformations in each split mold, but because the outer mold is ring-shaped, deformation of the outer mold due to repeated use can be suppressed, and an expandable body of an appropriate shape can be manufactured.

[0011] (4) In the method for manufacturing the expandable body described in (2) or (3) above, the same first inner mold and the same outer mold may be used in the first step and the second step to form the two halves located on both sides of the bottom in the axial direction, respectively. This allows the two halves sandwiching the bottom to be formed in the same shape.

[0012] (5) In the method for manufacturing an expandable body according to any one of (2) to (4) above, in the second step, the inside of the one side formed in the first step may be supported by a support inner mold having a convex portion protruding radially outward, thereby preventing the shape of the one side formed in the first step from being deformed in the second step and allowing the shape of the one side formed in the first step to be properly maintained.

[0013] (6) In the method for manufacturing an expandable body described in any one of (2) to (5) above, in the first step, the vicinity of the bottom on the inside of the other side to be formed in the second step may be expanded using a second inner mold having a constant outer diameter portion that is axially continuous and has approximately the same outer diameter as the bottom. This allows the other side to be deformed to the same extent as the bottom when forming one side in the first step. This reduces strain generated in the expandable body in the second step and suppresses breakage of the expandable body.

[0014] (7) The method for manufacturing an expandable body according to any one of (2) to (6) above may include, in the first step, expanding the inner side of the other side to be formed in the second step near the bottom with a second inner mold having a constant outer diameter portion that is axially continuous and has approximately the same outer diameter as the bottom, and in the second step, forming the other side using the first inner mold and the outer mold, while supporting the inner side of the one side formed in the first step with a supporting inner mold having a protrusion that protrudes radially outward. This allows the first and second steps to use the same first inner mold and outer mold, making it easy to form the two sides sandwiching the bottom in the same shape.

[0015] (8) In the method for manufacturing an expandable body according to any one of (2) to (7) above, the base material may be expanded into a spindle shape using a preforming mold having a maximum outer diameter smaller than the inner diameter of the bottom of the first inner mold before the first step. This allows the base material to be deformed to a certain extent before the first step. This reduces strain generated in the expandable body in the first step, thereby suppressing breakage of the expandable body.

[0016] (9) The method for manufacturing an expandable body according to any one of (2) to (8) above may include, before the first step, a step of forming a plurality of first slits along the axial direction in a first end portion of the base material, and in the first step and the second step, the first end portion may be widened and the inner mold may be inserted into the base material from the first end portion. This makes it easier for the first end portion to be widened, making it easier to insert the inner mold into the base material from the first end portion and place it at a desired position.

[0017] (10) In the method for manufacturing an expandable body described in (9) above, after the second step, a ring-shaped connecting part that is disposed at a second end of the base material opposite the first end and that maintains the cylindrical shape of the second end may be separated from the base material. This allows the method for manufacturing an expandable body to easily and firmly fix the second end to the distal end of the shaft part.

[0018] (11) The method for manufacturing an expandable body according to (9) or (10) above may include forming a second slit in the second end along the axial direction and forming a restricting portion that restricts the expansion of the second slit. This makes it easy to insert a shaft portion, which is the connection target, into the second end by releasing the restricting portion. Furthermore, after inserting the shaft portion into the second end, restricting the expansion of the second slit with the restricting portion makes it easy to fix the second end to the shaft portion.

[0019] (12) A manufacturing method for an expandable body assembly according to the present invention, which achieves the above-mentioned object, includes cutting out a cylindrical base material to form a plurality of struts extending in the axial direction of the base material and arranged circumferentially surrounding the axial direction, and forming a fixed portion at a second end opposite a first axial end of the base material, the fixed portion having a second slit along the axial direction and a regulating portion that regulates the expansion of the second slit, and a ring-shaped connecting portion that is connected to the fixed portion and maintains the cylindrical shape of the fixed portion, and by using a mold to radially deform the plurality of struts of the base material, an expandable body having a waist portion whose outer diameter decreases midway in the axial direction is formed, and after the expansion body is formed, the ring-shaped connecting portion is separated from the fixed portion, and the regulation of the regulating portion is released to expand the second slit, a long shaft portion is inserted inside the expansion body, and the second end portion is placed over the tip portion of the shaft portion, and then the regulating portion regulates the expansion of the second slit, and the second end portion is fixed to the tip portion of the shaft portion. This makes it easy to manufacture the expandable body and the expandable body assembly because the cylindrical shape of the fixing portion, which tends to expand due to the second slit, can be suppressed by the ring-shaped connecting portion until the expandable body is created from the base material and fixed to the shaft portion. Furthermore, after the expandable body is created, the ring-shaped connecting portion can be cut off to widen the second slit, making it easy to insert the shaft portion into the second end and fix the second end to the shaft portion with the restricting portion.

[0020] The medical device (13) according to the present invention, which achieves the above object, comprises an expansion body formed by a plurality of struts extending along an axial direction and arranged in a circumferential direction surrounding the axial direction, and a long shaft portion connected to a base end of the expansion body, wherein the base end of the expansion body has a tubular fixing portion having at least one base end slit formed along the axial direction and capable of opening and closing the slit, and one of two edges of the fixing portion sandwiching the base end slit is formed with a convex portion that protrudes circumferentially toward the other, and the other is formed with a concave portion cut out so that the convex portion fits into the convex portion, and the base end slit is closed so as to include the boundary between the convex portion and the concave portion. The medical device has a protrusion having a base portion formed at one circumferential end and an apex portion formed at the other circumferential end and having a length in the axial direction of the expandable body longer than the base portion, the recess having an open apex portion that receives the base portion of the protrusion and an open bottom portion that communicates with the open apex and receives the apex of the protrusion, the circumferential length of the apex being shorter than the circumferential length of the open bottom, the protrusion fitting into the recess, and the base end of the expandable body being fixed to the shaft portion with a circumferential gap formed between the apex of the protrusion and the open bottom of the recess. This allows the expandable body to be fixed to the shaft portion by connecting the apex of the protrusion to the open bottom of the recess. Furthermore, because a circumferential gap is formed between the apex of the protrusion and the open bottom of the recess, the second end can be securely fixed to the shaft portion even if the outer diameter of the shaft portion varies.

[0021] (14) In the medical device described in (13) above, the base end of the fixing part may have a cut mark where the ring-shaped connecting part is cut. This allows the cylindrical shape of the fixing part to be maintained by the ring-shaped connecting part until needed during manufacturing, making the medical device easy to manufacture.

[0022] (15) In the medical device described in (14) above, the base end of the fixing part may have a recess that is recessed toward the tip of the expandable body and has the cut mark portion disposed therein, thereby preventing the cut mark portion from coming into contact with and damaging other medical devices or biological tissue.

[0023] (16) In the medical device according to any one of (13) to (15), the plurality of struts may comprise multiple sets of strut groups extending toward the proximal end of the expandable body, and the fixing portion may have at least one separation portion circumferentially separated by the proximal end slit, each separation portion being connected to a respective proximal end of the strut group. In this way, the separation portions of the medical device are formed to match the strut groups, thereby preventing distortion of the shape of the expandable body due to excessive separation portions.

[0024] (17) In the medical device according to any one of (13) to (16), the distal end portions of the plurality of struts may include a plurality of distal struts that extend axially and are independent of one another in the circumferential direction, and the distal end portion of the expandable body may include a distal shaft portion that secures the plurality of distal struts so that adjacent two of the plurality of distal struts do not separate from one another in the circumferential direction. This configuration makes it possible to suppress distortion of the shape of the distal end portion of the expandable body, since the medical device has a plurality of independent distal struts secured to the distal shaft portion.

[0025] 1 is a side view showing a medical device having an expansion body; FIG. 2 is a side view showing the distal end of a medical device; FIG. 3 is a perspective view showing a mold together with a core material and a fixing member; FIG. 4 is a cross-sectional view showing a mold; FIG. 5 is a cross-sectional view showing a first use example of the mold; FIG. 6 is a cross-sectional view showing a second use example of the mold; FIG. 7 is a side view showing a base material; FIG. 8 is a side view showing a state in which a preforming mold is inserted into the base material; FIG. 9 is a side view showing a state in which a first inner mold and a second inner mold are inserted into the base material; FIG. 10 is a side view showing a state in which an outer mold is placed over the base material into which the first inner mold and the second inner mold have been inserted; FIG. 11 is a side view showing a base material from which the mold has been removed; FIG. 12 is a side view showing a state in which an outer mold is placed over the base material into which the first inner mold has been inserted, and further, a support inner mold is inserted into the base material; FIG. 13 is a side view showing a manufactured expansion body; FIG. 14 is a side view showing a second end of the expansion body, where (A) shows a state in which the restriction of the restriction part is released, and (B) shows a state in which the restriction of the restriction part is activated. 10A and 10B are side views showing modified examples of the expandable body, expandable body assembly, and medical device, respectively.

[0026] 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 side," and the side that is operated will be referred to as the "proximal side."

[0027] The expandable body 21 manufactured by the manufacturing method for the expandable body 21 according to this embodiment is used in the medical device 10 shown in Fig. 1. The medical device 10 is configured to expand a puncture hole formed in the atrial septum of a patient's heart and to perform a maintenance procedure to maintain the expanded puncture hole at its original size. Note that the medical device 10 in which the expandable body 21 can be used is not particularly limited.

[0028] As shown in Figures 1 and 2, the medical device 10 has a long portion 20 extending from the base end to the tip, an expansion body 21 provided at the tip end of the long portion 20, an electrode portion 22 which is an energy transmission element provided along the expansion body 21, and a hand-operated operating portion 23 connected to the base end of the long portion 20.

[0029] The long portion 20 has a shaft portion 31 that holds the expansion body 21 at its tip, a tip shaft portion 34 that is fixed to the tip of the expansion body 21, an outer tube 30 that houses the shaft portion 31, a traction shaft 33, and a tip tip 35 that is fixed to the tip of the traction shaft 33.

[0030] The shaft portion 31 is a long tubular body extending from the handheld operation portion 23 to the base end of the expansion body 21. The base end of the shaft portion 31 is fixed to the tip end of the handheld operation portion 23. The tip end of the shaft portion 31 is fixed to the base end of the expansion body 21. The tip shaft portion 34 is a tubular body fixed to the tip end of the expansion body 21. The tip shaft portion 34 is positioned closer to the tip side than the shaft portion 31 and spaced apart from it.

[0031] The outer tube 30 is a long tubular body that covers the shaft portion 31 and is movable back and forth in the axial direction (toward the axis of the long portion 20) relative to the shaft portion 31. When the outer tube 30 is moved toward the distal end of the long portion 20, it can house the expandable body 21, which has been contracted radially, inside it. The radial direction is a direction perpendicular to the axis of the shaft portion 31. When the expandable body 21 is housed inside the outer tube 30, the surgeon can move the outer tube 30 toward the proximal end, exposing the expandable body 21 from the outer tube 30 and allowing the expandable body 21 to expand radially due to its restoring force.

[0032] The traction shaft 33 is a long tubular body disposed inside the shaft portion 31 and the distal shaft portion 34, and is movable back and forth in the axial direction relative to the shaft portion 31. The traction shaft 33 protrudes distally from the distal end of the shaft portion 31, and protrudes distally from the distal end of the expandable body 21. The distal end of the traction shaft 33, which is located distally of the expandable body 21, is fixed to the distal tip 35. The proximal end of the traction shaft 33 is led out proximally from the proximal operation unit 23. A guidewire lumen is formed inside the traction shaft 33 along the axial direction, allowing a guidewire to be inserted therethrough. The traction shaft 33 is movable axially relative to the shaft portion 31.

[0033] The distal tip 35 is an annular member fixed to the outer peripheral surface of the distal end of the traction shaft 33, and protrudes radially outward from the outer peripheral surface of the traction shaft 33. The distal tip 35 is not fixed to the expansion body 21. The outer diameter of the distal tip 35 is larger than the inner diameter of the distal end of the expansion body 21. Therefore, the distal tip 35 abuts against the distal end of the expansion body 21 from the distal side, and pulls the expansion body 21 toward the proximal end, thereby applying a compressive force to the expansion body 21 that compresses it along the axial direction of the shaft portion 31.

[0034] The expandable body 21 has a plurality of struts 50 extending axially and aligned circumferentially. The struts 50 branch and merge along the axial direction to form a mesh-like structure. This allows the expandable body 21 to expand and contract radially. The struts 50 include a plurality of distal struts 50A located distally of a waist portion 55 where the outer diameter decreases, and a plurality of proximal struts 50B located proximal to the waist portion 55. The proximal struts 50B form two strut groups 50C. The proximal struts 50A included in each strut group 50C are connected to the same separation portion 186A, which will be described later.

[0035] The expandable body 21 is tapered so that its diameter increases radially from both axial ends toward the center. The expandable body 21 also has a constricted shape in the axial center, where its outer diameter rapidly decreases. Specifically, the expandable body 21 includes a ring-shaped distal connecting portion 51 located at the distal end, a ring-shaped proximal connecting portion 52 located at the proximal end, a distal convex portion 53 located at the proximal end of the distal connecting portion 51 and protruding radially outward, a proximal convex portion 54 located at the distal end of the proximal connecting portion 52 and protruding radially outward, and a waist portion 55 located between the distal convex portion 53 and the proximal convex portion 54, whose outer diameter decreases.

[0036] The distal connecting portion 51 is a ring-shaped portion where the distal ends of a plurality of circumferentially arranged struts 50 are connected. The proximal connecting portion 52 is a ring-shaped portion where the proximal ends of a plurality of circumferentially arranged struts 50 are connected. The distal connecting portion 51 is connected to the distal shaft portion 34. The proximal connecting portion 52 is connected to the shaft portion 31.

[0037] The waist portion 55 has a bottom portion 56 that is the innermost in the radial direction, a base end side upright portion 57 that extends radially outward from the base end of the bottom portion 56, and a tip end side upright portion 58 that extends radially outward from the tip end of the bottom portion 56. The waist portion 55 defines a receiving space 59 that can receive biological tissue when the expandable body 21 is expanded.

[0038] When the traction shaft 33 slides relative to the shaft portion 31 in the proximal direction and a compressive force acts on the expandable body 21, the distal upright portion 58 and the proximal upright portion 57 approach each other and come into close contact with the biological tissue received in the receiving space 59. The proximal upright portion 57 has an electrode portion 22 arranged along the waist portion 55 so as to face the receiving space 59. That is, the electrode portion 22 is provided along the expandable body 21, at a middle portion in the axial direction of the expandable 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 58.

[0039] The expandable body 21 can be formed by laser cutting or the like from a single metal cylindrical member. The expandable body 21 can be formed from a metal material. Examples of such metal materials 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 shape-memory alloy with high elasticity, such as a nickel-titanium alloy. However, the material of the expandable body 21 is not limited to these, and other materials may also be used.

[0040] The electrode units 22 are provided on the conductive unit 60 of the expansion body 21 and are connected to an external energy supply device (not shown) via the conductive unit 60. A high-frequency voltage is applied from the energy supply device via the conductive unit 60 to an electrode pair consisting of the two electrode units 22, thereby providing energy between them. In other words, the electrode units 22 are configured as bipolar electrodes.

[0041] When the expandable body 21 is expanded, the electrode 22 is disposed on the surface of the base-side upright portion 57 facing the distal end. Because the electrode 22 is provided on the base-side upright portion 57, when the waist portion 55 clamps the atrial septum, energy from the electrode 22 is transmitted to the atrial septum from the right atrium. If the electrode 22 were provided on the distal upright portion 58, energy from the electrode 22 would be transmitted to the atrial septum from the left atrium.

[0042] The handheld operation unit 23 has a housing 80 that is held by the surgeon and an operation unit 81 that the surgeon can move along the axial direction of the traction shaft 33. The housing 80 is fixed to the base end of the shaft portion 31, and the operation unit 81 is fixed to the base end of the traction shaft 33.

[0043] The medical device 10 is used in treatment of patients suffering from chronic heart failure, a condition in which the myocardium of the left ventricle of the heart becomes enlarged and stiff, resulting in elevated blood pressure in the left atrium. The medical device 10 is inserted partway through the expandable body 21 into a puncture hole in the atrial septum. Therefore, the edge of the puncture hole formed in the atrial septum is positioned within the receiving space 59 defined by the waist portion 55. When the traction shaft 33 is pulled proximally relative to the shaft portion 31, a compressive force acts on the expandable body 21, causing the distal upright portion 58 and the proximal upright portion 57 to approach each other, and pressing the electrode portion 22 located on the proximal upright portion 57 against biological tissue. In this state, the medical device 10 applies high-frequency energy to the edge of the puncture hole through the electrode portion 22, thereby cauterizing (heating and cauterizing) the edge of the puncture hole with the high-frequency energy. This inhibits the puncture hole from closing due to natural healing, and allows the size of the hole to be maintained.

[0044] Next, we will explain the manufacturing apparatus for the expandable body 21. When manufacturing the expandable body 21, a mold 100, a core material 170, and a fixing tool 160 are used, as shown in Figures 3 and 4. The mold 100 has a preforming mold 110, a first inner mold 120 (inner mold), a second inner mold 130 (inner mold), a supporting inner mold 140 (inner mold), and an outer mold 150.

[0045] The core material 170 is a cylindrical member that can penetrate the first inner mold 120, the second inner mold 130, and the support inner mold 140 to support them. The fixture 160 has a ring-shaped fixture 161 that can be fitted over the end of the expandable body 21, and a positioning fixture 162 that can be fixed to the core material 170 with a screw or the like.

[0046] The first inner mold 120 is a mold that forms one side located on one axial side (tip side or base side) of the bottom 56 of the expandable body 21, and can be inserted into the inside of the base material 180 (see FIG. 7 ) before it becomes the expandable body 21. The first inner mold 120 has a first inner mold recess 121 having a shape corresponding to the inner surface (radially inner surface) of the bottom 56 of the expandable body 21, a first inner mold inclined portion 122 having a shape corresponding to the inner surface of the upright portion of the expandable body 21 (tip side upright portion 58 and / or base side upright portion 57), and a first inner mold convex portion 123 having a shape corresponding to the inner surface of the convex portion of the expandable body 21 (tip side convex portion 53 and / or base side convex portion 54). The first inner mold 120 further has a first connecting portion 125 connectable to the second inner mold 130 and the supporting inner mold 140, a step portion 126 located between the first inner mold recess 121 and the first connecting portion 125, and a first through hole 124 that penetrates in the axial direction and into which a core material 170 can be tightly inserted. The first connecting portion 125 can be mated and connected to a second connecting portion 133 of the second inner mold 130 or a third connecting portion 144 of the supporting inner mold 140, which will be described later. The first inner mold recess 121, first inner mold inclined portion 122, and first inner mold protrusion 123 are formed with a uniform outer diameter (circular in cross section) in the circumferential direction around the central axis of the first through hole 124.

[0047] The second inner die 130 is connected to the first inner die 120 and can be inserted, together with the first inner die 120, into the base material 180 before it becomes the expandable body 21. The second inner die 130 has a constant outer diameter portion 131 that continues axially from the side connected to the first inner die 120 and has an outer diameter that is approximately the same as the inner diameter of the inner surface of the bottom 56 of the expandable body 21 (or the outer diameter of the first inner die recess 121 of the first inner die 120), and a tapered portion 132 that has an outer diameter that tapers off from the end of the constant outer diameter portion 131. The second inner die 130 further has a second connecting portion 133 that can be connected to the first connecting portion 125 of the first inner die 120, and a second through-hole 134 that penetrates axially and allows the core material 170 to be inserted in close contact with the second connecting portion 133. The first connecting portion 125 can be fitted into the second connecting portion 133. The constant outer diameter portion 131 and the tapered portion 132 are formed with a uniform outer diameter (circular in cross section) in the circumferential direction around the central axis of the second through hole 134 .

[0048] The support inner mold 140 is connected to the first inner mold 120 and can be inserted, together with the first inner mold 120, into the base material 180 before it becomes the expandable body 21. The support inner mold 140 has a support inner mold recess 141 shaped to correspond to the bottom 56 of the expandable body 21, a support inner mold inclined portion 142 shaped to correspond to the upright portion (distal upright portion 58 or base upright portion 57) of the expandable body 21, and a support inner mold convex portion 143 shaped to correspond to the convex portion (distal convex portion 53 or base convex portion 54) of the expandable body 21. The support inner mold 140 further has a third connecting portion 144 connectable to the first connecting portion 125 of the first inner mold 120 and a third through-hole 145 that penetrates in the axial direction and allows the core material 170 to be inserted in close contact. The first connecting portion 125 can be fitted into the third connecting portion 144. The third connecting portion 144 has a shape similar to that of the second connecting portion 133, which is similarly connectable to the first connecting portion 125. The support inner mold recess 141, the support inner mold inclined portion 142, and the support inner mold protrusion 143 are formed with a uniform outer diameter (circular in cross section) in the circumferential direction around the central axis of the third through hole 145.

[0049] The outer mold 150 is a generally ring-shaped mold that can be positioned radially outward of the first inner mold 120 to surround the first inner mold 120. The outer mold 150 is used to sandwich the base material 180 between the first inner mold 120 and the outer mold 150 to shape the base material 180. The outer mold 150 has an outer mold convex portion 151 having a shape corresponding to the outer surface (radially outer surface) of the bottom 56 of the expandable body 21, an outer mold inclined portion 152 having a shape corresponding to the outer surface of the upright portion (distal upright portion 58 and / or base upright portion 57) of the expandable body 21, an outer mold concave portion 153 having a shape corresponding to the outer surface of the convex portion (distal upright portion 53 and / or base upright portion 54) of the expandable body 21, and a constant inner diameter portion 154 that continues in the axial direction and has approximately the same inner diameter as the outer mold concave portion 153. The outer mold 150 further has a fourth through-hole 155 through which the first inner mold 120 can be inserted. The outer mold convex portion 151 protrudes radially inward and has the smallest inner diameter of the outer mold 150. The outer mold 150 is formed with a uniform inner diameter (circular in cross section) in the circumferential direction around the central axis of the fourth through hole 155.

[0050] The preforming mold 110 is a spindle-shaped mold having a maximum outer diameter smaller than the outer diameter of the first inner mold recess 121 .

[0051] The mold 100 can be made of a metal material, such as stainless steel, carbon steel, copper, or brass.

[0052] The first inner mold 120, the second inner mold 130, and the outer mold 150 can be connected as shown in a first example of use in Fig. 5. Furthermore, the first inner mold 120, the supporting inner mold 140, and the outer mold 150 can be connected as shown in a second example of use in Fig. 6.

[0053] Next, a method for manufacturing the expansion body 21 and expansion body assembly 240 according to this embodiment will be described with reference to the flowchart shown in Fig. 16. As shown in Fig. 15, the expansion body assembly 240 is a component in which the shaft portion 31 and the tip shaft portion 34 are connected to the expansion body 21, and does not include the electrode portion 22, the traction shaft 33, the hand-operated operation portion 23, etc. The expansion body assembly 240 does not necessarily need to have the tip shaft portion 34 connected.

[0054] First, the manufacturer prepares a metal cylindrical member before it becomes the expandable body 21, and cuts out the base material 180 by laser processing or the like, as shown in Figure 7 (Step S1). The base material 180 has multiple cuts 181 formed therethrough, penetrating from the outer circumferential surface to the inner circumferential surface, and struts 50 are formed between adjacent cuts 181. The base material 180 also has a first end 182 and a second end 183 formed therein.

[0055] The first end 182 is the portion that becomes the tip-side connecting portion 51 of the expansion body 21, and has a plurality of first slits 184 extending from the tip surface of the base material 180 to the cut portion 181 located between circumferentially adjacent struts 50.

[0056] The second end 183 includes a portion that will become the base-end connecting portion 52 of the expansion body 21, and has a ring-shaped connecting portion 185 located at the base end of the base material 180, a fixing portion 186 located on the distal side (or on the first end 182 side) of the ring-shaped connecting portion 185, and a cutting portion 187 connecting each fixing portion 186 to the ring-shaped connecting portion 185. The ring-shaped connecting portion 185 is a ring-shaped portion that extends 360 degrees.

[0057] The fixing portion 186 has at least one second slit 188 (two in this embodiment) in the circumferential direction and two separation portions 186A separated by the two second slits 188. The two separation portions 186A are connected by a restriction portion 189 that can be hooked together and separated. The restriction portion 189 is formed in the second slit 188. Note that there may be only one second slit 188. In this case, the fixing portion 186 does not have the separation portion 186A, and can be opened to widen the single first slit 188.

[0058] The restricting portion 189 can be connected, for example, so that a T-shaped protrusion 200 can be hooked onto a recess 210 having a cut-out T shape. The protrusion 200 has a base portion 201 formed at one circumferential end and an apex portion 202 formed at the other circumferential end and having a longer length in the axial direction of the expandable body 21 than the base portion 201. The recess 210 has an open top portion 211 that receives the base portion 201 of the protrusion 200, and an open bottom portion 212 that communicates with the open top portion 211 and receives the top portion 202 of the protrusion 200. The circumferential length of the top portion 202 is shorter than the circumferential length of the open bottom portion 212. The protruding portion 200 is fitted into the recessed portion 210, and a circumferential gap 220 is formed between the apex 202 of the protruding portion 200 and the opening bottom 212 of the recessed portion 210, and the proximal end of the expansion body 21 is fixed to the shaft portion 31 (see FIG. 14(B)). Note that, in this embodiment, the apex 202 protrudes both distally and proximally relative to the base portion 201, but it may protrude only distally or proximally relative to the base portion 201.

[0059] The base end of the fixing portion 186 has a recessed portion 230 that recesses toward the tip of the expandable body 21. The cutting portion 187 is connected to the fixing portion 186 within the recessed interior of the recessed portion 230. The cutting portion 187 is formed to taper from the ring-shaped connecting portion 185 toward the recessed portion 230. Therefore, the cutting portion 187 can be cut at a position closer to the recessed portion 230 than the ring-shaped connecting portion 185. When the cutting portion 187 is cut, a cut mark 231 is formed within the recessed interior of the recessed portion 230.

[0060] The ring-shaped connecting portion 185 prevents the connection between the convex portion 200 and the concave portion 210 in the restricting portion 189 from being released and the second slit 188 of the fixing portion 186 from opening (the plurality of separating portions 186A from each other), thereby maintaining the appropriate shape of the base material 180 until the expansion body 21 is manufactured. Note that the restricting portion 189 is not particularly limited as long as it can connect and separate the opposing edges of the second slit 188 of the fixing portion 186.

[0061] Next, the manufacturer forms the expandable body 21 from the member 180 (step S2). To do so, the manufacturer forcibly widens the first slit 184 at the first end 182 of the base material 180 and inserts the preforming mold 110 into the base material 180 through the opening of the widened first end 182, as shown in FIG. 8. Next, the manufacturer places the ring-shaped fastener 161 over the outside of the first end 182 and the second end 183, keeping the first slit 184 at the first end 182 and the second slit 188 at the second end 183 closed, and performs heat treatment (heating and heat radiation). This causes the base material 180 to be shaped to the shape of the preforming mold 110.

[0062] Next, the manufacturer removes the ring-shaped fixtures 161 from the first end 182 and the second end 183, forcibly widens the slit in the first end 182 of the base material 180, and removes the preforming mold 110 from the widened opening of the first end 182. Subsequently, as shown in FIGS. 5 and 9 , the manufacturer inserts the second inner mold 130 and the first inner mold 120 into the base material 180 through the opening of the first end 182. At this time, the manufacturer connects the first connecting portion 125 and the second connecting portion 133, inserts the core material 170 into the first through hole 124 and the second through hole 134, and places the second inner mold 130 on one side of the base material 180 facing the second end 183, and places the first inner mold 120 on one side of the base material 180 facing the first end 182. Next, as shown in FIG. 10 , the manufacturer places a ring-shaped fixture 161 over the first end 182 and fixes it, restricts axial movement of the first end 182 with the positioning fixture 162, and places the outer die 150 over the outside of the first inner die 120 from the base end side. As a result, one side of the base material 180 closer to the first end 182 is pushed outward by the first inner die 120, and outward deformation is restricted by the outer die 150. Next, the manufacturer places a ring-shaped fixture 161 over the second end 183 to close the second slit 188, and restricts axial movement of the second end 183 with the positioning fixture 162. Next, the manufacturer performs heat treatment. This allows the base material 180 to be shaped to the shapes of the first inner die 120, the second inner die 130, and the outer die 150. In particular, the base material 180 is given the shape (see FIG. 2 ) of the distal upright portion 58 and the distal convex portion 53 from the bottom portion 56 of the expandable body 21 by the first inner mold 120 and the outer mold 150. Also, the base material 180 is given a certain amount of the shape of the expandable body 21 from the bottom portion 56 to the base end by the second inner mold 130.

[0063] Next, the manufacturer temporarily removes the outer die 150, the first inner die 120, the second inner die 130, the core material 170, and the fixture 160 from the base material 180, as shown in FIG. 11 . Next, the manufacturer again widens the first slit 184 of the first end 182 of the base material 180, and inserts the first inner die 120 into the base material 180 through the opening of the first end 182, as shown in FIGS. 6 and 12 , and positions the first inner die 120 on one side of the second end 183. Next, the manufacturer inserts the core material 170 into the first through-hole 124, covers the second end 183 with the ring-shaped fixture 161 to close the second slit 188, restricts axial movement of the second end 183 with the positioning fixture 162, and then covers the base material 180, which is covering the first inner die 120, from the tip side. As a result, one side of the base material 180 near the second end 183 is pushed outward by the first inner die 120 , and the outer die 150 restricts the outward deformation.

[0064] Next, the manufacturer again widens the first slit 184 of the first end 182 of the base material 180, inserts the supporting inner mold 140 into the inside of the base material 180 through the opening of the first end 182, and places the supporting inner mold 140 on one side of the already shaped first end 182. At this time, the manufacturer connects the third connecting portion 144 of the supporting inner mold 140 to the first connecting portion 125 of the first inner mold 120 and passes the core material 170 through the third through-hole 145. Next, the manufacturer places the ring-shaped fixture 161 over the first end 182 to close the first slit 184, and uses the positioning fixture 162 to restrict axial movement of the first end 182. Next, the manufacturer applies heat treatment. This causes the base material 180 to be shaped to the shapes of the first inner mold 120, the supporting inner mold 140, and the outer mold 150. In particular, the base material 180 is given the shape (see FIG. 2) of the base portion 56 of the expandable body 21, the base-side rising portion 57, and the base-side convex portion 54 by the first inner mold 120 and the outer mold 150.

[0065] 13, the manufacturer removes the outer mold 150, the first inner mold 120, the supporting inner mold 140, the core material 170, and the fixtures 160 from the base material 180. In this way, the expandable body 21 is produced.

[0066] Before connecting the expansion body 21 to the shaft portion 31, the manufacturer cuts the cutting portion 187 to separate the ring-shaped connecting portion 185 from the fixing portion 186, as shown in FIG. 14A. Next, the manufacturer removes the convex portion 200 of the restricting portion 189 of the second end portion 183 from the concave portion 210 to release the restricting portion 189 and separates the two separating portions 186A to widen the second slit 188 (step S3). This allows the second end portion 183 to easily fit over the shaft portion 31. Next, the manufacturer inserts the shaft portion 31 into the second end portion 183 (step S4). Next, the manufacturer connects the convex portion 200 of the restricting portion 189 to the concave portion 210 to fix the expansion body 21 to the shaft portion 21 (step S5), as shown in FIG. 14B. At this time, the circumferential position of the apex 202 of the protrusion 200 within the opening bottom 212 of the recess 210 can be adjusted within the range of the gap 220, so that the second end 183 can be connected to the shaft portion 31 even if there is variation in the outer diameter of the shaft portion 31. This allows the second end 183 to be firmly connected to the shaft portion 31. The first end 182, which is divided into multiple pieces, can be easily connected by gathering them together on the outer circumferential surface of the shaft portion 31.

[0067] 15 , the manufacturer assembles and fixes the multiple divided first end portions 182 (distal struts) to the outer circumferential surface of the distal shaft portion 34 so as to prevent the distal end portion of the expandable body 21 from spreading due to the first slits 184 (step S6). This produces the expandable body assembly 240. Note that the fixation of the first end portion 182 to the distal shaft portion 34 may be performed before the fixation of the second end portion 183 to the shaft portion 31 or before the detachment of the ring-shaped connecting portion 185 from the second end portion 183.

[0068] As described above, the method for manufacturing the expandable body 21 according to this embodiment is a method for manufacturing an expandable body 21 formed by a plurality of struts 50 extending along the axial direction and arranged circumferentially surrounding the axial direction, and having a waist portion 55 whose outer diameter decreases midway in the axial direction, and in which the inner mold expands the inside of a tubular base material 180 on which the plurality of struts 50 are formed, while the outer mold 150 restricts the outside of the base material 180, in order to form the bottom portion 56 having the smallest outer diameter of the waist portion 55 and the upright portions (distal upright portions 58 and / or base upright portions 57) extending radially outward from the bottom portion 56. In this way, the method for manufacturing the expandable body 21 forms the bottom portion 56 and the upright portions of the waist portion 55 using the inner mold and outer mold 150, thereby reducing strain that occurs in the expandable body 21 due to sudden deformation during manufacturing and suppressing breakage of the expandable body 21.

[0069] The manufacturing method of the expandable body 21 includes a first step of forming one side of the expandable body 21 located on one axial side of the bottom 56 using the first inner mold 120 and the outer mold 150 together with the bottom 56, and a second step of forming the other side located on the opposite side of the expandable body 21. As a result, the manufacturing method of the expandable body 21 forms the two sides of the expandable body 21 in separate steps, thereby reducing distortion that occurs in the expandable body 21 and suppressing breakage of the expandable body 21.

[0070] The inner mold includes a first inner mold 120, and in the manufacturing method of the expandable body 21, in the first and second steps, a non-split ring-shaped outer mold 150 is placed over the outside of the base material 180 into which the first inner mold 120 has been inserted. If the outer mold 150 is a split mold, repeated use can cause different deformations in each split mold, but because the outer mold 150 is ring-shaped, deformation of the outer mold 150 due to repeated use can be suppressed, and an expandable body 21 with an appropriate shape can be manufactured.

[0071] In the manufacturing method of the expandable body 21, the same molds (first inner mold 120 and outer mold 150) are used in the first and second steps to form each half located on either side of the bottom 56 in the axial direction. This allows the two half sides sandwiching the bottom 56 to be formed in the same shape.

[0072] In the manufacturing method of the expandable body 21, in the second step, the inside of the one side formed in the first step is supported by a supporting inner mold 140 having a convex portion that protrudes radially outward. This makes it possible to suppress deformation of the shape of the one side formed in the first step in the second step and to properly maintain the shape of the one side formed in the first step.

[0073] In the manufacturing method of the expandable body 21, in the first step, the vicinity of the inner bottom 56 of the other side to be formed in the second step is expanded by a second inner mold 130 having a constant outer diameter portion 131 that continues in the axial direction and has approximately the same outer diameter as the bottom 56. This makes it possible to deform the other side to the same extent as the bottom 56 when forming one side in the first step. This reduces the strain that occurs in the expandable body 21 in the second step, making it possible to suppress breakage of the expandable body 21.

[0074] The manufacturing method of the expandable body 21 involves, in a first step, expanding the area near the inner bottom 56 of the other side to be formed in the second step with a second inner mold 130 having a constant outer diameter portion 131 that continues in the axial direction and has approximately the same outer diameter as the bottom 56, and in a second step, forming the other side using a first inner mold 120 and an outer mold 150, while supporting the inside of the side formed in the first step with a supporting inner mold 140 having a convex portion that protrudes radially outward. This allows the first inner mold 120 and outer mold 150 to be used in the first and second steps, making it easy to form the two sides sandwiching the bottom 56 in the same shape.

[0075] In the manufacturing method of the expandable body 21, before the first step, the base material 180 is expanded into a spindle shape using a preforming mold 110 having a maximum outer diameter smaller than the inner diameter of the bottom 56 of the first inner mold 120. This allows the base material 180 to be deformed to a certain extent before the first step. This reduces the strain generated in the expandable body 21 in the first step, and makes it possible to suppress breakage of the expandable body 21.

[0076] The manufacturing method of the expandable body 21 includes, before the first step, a step of forming a plurality of first slits 184 along the axial direction in a first axial end 182 of the base material 180, and in the first and second steps, the first end 182 is expanded and an inner mold is inserted into the inside of the base material from the first end 182. This makes it easier for the first end 182 to expand, making it easier to insert the inner mold into the inside of the base material 180 from the first end 182 and place it at the desired position.

[0077] In the manufacturing method of the expandable body 21, after the second step, the ring-shaped connecting portion 185, which is disposed at the second end 183 opposite the first end 182 of the base material 189 and maintains the cylindrical shape of the second end 183, is separated from the base material 180. This allows the manufacturing method of the expandable body 21 to easily and firmly fix the second end 183 to the tip end of the shaft portion 31.

[0078] The manufacturing method of the expandable body 21 includes the steps of forming a second slit 188 along the axial direction in the second end 183 and forming a restricting portion 189 that restricts the expansion of the second slit 188. This makes it easy to insert the shaft portion 31, which is the object to be connected, into the second end 183 by releasing the restricting portion 189. Furthermore, after the shaft portion 31 is inserted into the second end 183, the restricting portion 189 restricts the expansion of the second slit 188, making it easy to fix the second end 183 to the shaft portion 31.

[0079] Furthermore, the manufacturing method of the expansion body assembly 240 in this embodiment involves cutting out a cylindrical base material 180 to form a plurality of struts 50 that extend in the axial direction of the base material 180 and are arranged in a circumferential direction surrounding the axial direction, and forming a cylindrical fixing portion 186 having a second slit 188 along the axial direction and a restricting portion 189 that restricts the expansion of the second slit 188 at a second end 183 opposite to a first axial end of the base material 180, and a ring-shaped connecting portion 185 that is connected to the fixing portion 186 and maintains the cylindrical shape of the fixing portion 186, and then cutting the plurality of struts 50 out of the base material 180 using a mold 100. By deforming the strut 50 in the radial direction, the expandable body 21 is formed, having a waist portion 55 whose outer diameter decreases midway in the axial direction. After the expandable body 21 is formed, the ring-shaped connecting portion 185 is separated from the fixing portion 186, the restriction of the restricting portion 189 is released to widen the second slit 188, the long shaft portion 31 is inserted into the expandable body 21, the fixing portion 186 of the second end portion 183 is placed over the tip of the shaft portion 31, and then the restriction portion 189 restricts the widening of the second slit 188, and the fixing portion 186 of the second end portion 183 is fixed to the tip of the shaft portion 31. This facilitates the manufacturing of the expandable body 21 and the expandable body assembly 240, since the cylindrical shape of the fixing portion 186 of the second end portion 183, which tends to widen due to the second slit 188, can be suppressed by the ring-shaped connecting portion 185 until the expandable body 21 is created from the base material 180 and fixed to the shaft portion 31. Furthermore, after creating the expansion body 21, the second slit 188 can be widened by cutting off the ring-shaped connecting portion 185, making it easier to insert the shaft portion 31 into the fixing portion 186 of the second end portion 183 and to fix the fixing portion 186 of the second end portion 183 to the shaft portion 31 using the regulating portion 189.

[0080] Furthermore, the medical device 10 in this embodiment comprises an expansion body 21 formed by a plurality of struts 50 extending along the axial direction and arranged in a circumferential direction surrounding the axial direction, and a long shaft portion 31 connected to the base end of the expansion body 21, and the base end of the expansion body 21 has a tubular fixing portion 186 in which at least one base end slit (second slit 188) is formed along the axial direction and which can open and close the slit, and one of the two edges sandwiching the base end slit of the fixing portion 186 is formed with a convex portion 200 that protrudes circumferentially toward the other, and the other is formed with a concave portion 210 that is cut so that the convex portion 200 can fit into it, and the base end slit is formed so as to include the boundary between the convex portion 200 and the concave portion 210 The convex portion 200 has a root portion 201 formed at one circumferential end and a top portion 202 formed at the other circumferential end and having a longer length in the axial direction of the expansion body 21 than the root portion 201, and the recess 210 has an open top portion 211 that receives the root portion 201 of the convex portion 200 and an open bottom portion 212 that is connected to the open top portion 211 and receives the top portion 202 of the convex portion 200, the circumferential length of the top portion 202 being shorter than the circumferential length of the open bottom portion 212, and the base end portion of the expansion body 21 is fixed to the shaft portion 31 in a state in which the convex portion 200 is fitted into the recess 210 and a circumferential gap 220 is formed between the top portion 202 of the convex portion 200 and the open bottom portion 212 of the recess 210. This allows the medical device 10 to connect the top 202 of the convex portion 200 of the expansion body 21 to the opening bottom 212 of the recess 210, thereby fixing the expansion body 21 to the shaft portion 31. Furthermore, because a circumferential gap 220 is formed between the top 202 of the convex portion 200 and the opening bottom 212 of the recess 210, the second end 183 can be well fixed to the shaft portion 31 even if there is variation in the outer diameter of the shaft portion 31.

[0081] The base end of the fixing part 186 has a cut mark 231 where the ring-shaped connecting part 185 was cut. This allows the cylindrical shape of the fixing part 186 to be maintained by the ring-shaped connecting part 185 until needed during manufacturing, making the medical device 10 easy to manufacture.

[0082] The base end of the fixing part 186 is recessed toward the tip of the expandable body 21 and has a recess 230 inside which a cut mark 231 is disposed. This prevents the cut mark 231 of the medical device 10 from coming into contact with and damaging other medical devices or biological tissues.

[0083] The struts 50 comprise multiple sets of strut groups 50C extending toward the base end of the expandable body 21, and the fixing portion 186 has at least one separation portion 186A circumferentially separated by a base end slit (second slit 188), with each separation portion 186A connected to the base end of a respective strut group 50C. As a result, the medical device 10 has separation portions 186A formed to match the strut groups 50C, preventing distortion of the shape of the expandable body 21 due to too many separation portions 186A.

[0084] The distal ends of the struts 50 include a plurality of distal struts 50A that extend axially and are independent of one another in the circumferential direction, and the distal end of the expandable body 21 includes a distal shaft 34 that secures the distal struts 50A so that adjacent pairs of the distal struts 50A do not become separated from one another in the circumferential direction. As a result, the medical device 10 has a plurality of independent distal struts 50A secured to the distal shaft 34, which can prevent distortion of the shape of the distal end of the expandable body 21.

[0085] 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. For example, as shown in Fig. 17, the outer mold 150 may have split molds 151 that can be separated in the circumferential direction. This allows each split mold 151 of the outer mold 150 to be separately positioned from the radially outer side relative to the first inner mold 120, making it easy to position the outer mold 150.

[0086] 18, the distal end of the base material 180 (expansion body 21) does not have to have a first end where the struts 50 are gathered. In this case, the distal end of the expansion body 21 to be produced has the tips of the multiple struts 50 spread out, as shown in FIG. 19. When a shaft portion 31 is inserted into and fixed to the second end 52 of the expansion body 21, an expansion body assembly 240 is produced, as shown in FIG. 20. The expansion body assembly 240 does not have a distal shaft portion. FIG. 21 shows a medical device 300 manufactured using this expansion body assembly 240. Instead of a pulling shaft, the medical device 300 has at least one pulling wire 301 connected to the control unit 81. The tip of the pulling wire 301 is fixed to the waist portion 55. Therefore, the diameter of the waist portion 55 can be adjusted by moving the pulling wire 301 in the proximal direction using the control unit 81.

[0087] Furthermore, in the manufacturing method of the expandable body assembly 240, the method of creating the expandable body 21 is not limited to the method shown in Fig. 13. For example, the expandable body 21 may be created by inserting an inner mold corresponding to the shape of the expandable body 21 inside the base material 180 and squeezing the position corresponding to the waist portion 55 of the base material 180 with a wire or the like.

[0088] This application is based on Japanese Patent Application No. 2023-169566, filed on September 29, 2023, the disclosures of which are incorporated herein by reference in their entirety.

[0089] 10, 300 Medical device 21 Expansion body 31 Shaft portion 34 Distal shaft portion 50 Strut 50A Distal strut 50B Proximal strut 50C Strut group 55 Waist portion 56 Bottom portion 57 Proximal side upright portion (upright portion) 58 Distal side upright portion (upright portion) 100 Mold 110 Preforming mold 120 First inner mold (inner mold) 130 Second inner mold (inner mold) 131 Constant outer diameter portion 140 Supporting inner mold (inner mold) 150 Outer mold 180 Base material 181 Cut portion 182 First end portion 183 Second end portion 184 First slit 185 Ring-shaped connecting portion 186 Fixing portion 186A Separation portion 187 Cutting portion 188 Second slit (proximal slit) 189 Restriction portion 200 Convex portion 201 Base portion 202 Top portion 210 Concave portion 211 Opening top portion 212 Opening bottom portion 220 Gap 230 Depression portion 231 Cutting trace portion 240 Expansion body assembly

Claims

1. A method for manufacturing an expandable body formed by a plurality of struts extending along an axial direction and arranged circumferentially surrounding the axial direction, and having a waist portion whose outer diameter decreases halfway along the axial direction, comprising the steps of: forming a bottom portion having the smallest outer diameter of the waist portion, and an upright portion extending radially outward from the bottom; wherein the inside of a cylindrical base material having a plurality of cuts formed therein is expanded with an inner mold, and the outside of the base material is restricted with an outer mold.

2. The method for manufacturing the expandable body described in claim 1, characterized in that the inner mold includes a first inner mold, and the method has a first step of forming one side of the expandable body located on one side of the bottom in the axial direction using the first inner mold and the outer mold together with the bottom, and a second step of forming the other side of the expandable body located on the opposite side to the one side.

3. A method for manufacturing an expandable body as described in claim 2, characterized in that in the first step and the second step, the outside of the base material into which the first inner mold is inserted is covered with the outer mold in the shape of a ring that is not a split mold.

4. A method for manufacturing an expandable body as described in claim 2, characterized in that in the first step and the second step, the same first inner mold and the same outer mold are used to form each of the sides located on both sides of the bottom in the axial direction.

5. A method for manufacturing an expandable body as described in claim 2, characterized in that in the second step, the inside of the one side formed in the first step is supported by a supporting inner mold having a convex portion protruding radially outward.

6. A method for manufacturing an expandable body as described in claim 2, characterized in that in the first step, the vicinity of the bottom on the inside of the other side to be formed in the second step is pushed out by a second inner mold having a constant outer diameter portion which is approximately the same outer diameter as the bottom and continues in the axial direction.

7. A method for manufacturing an expandable body as described in claim 2, characterized in that in the first step, the vicinity of the bottom on the inside of the other side to be formed in the second step is pushed out with a second inner mold having a constant outer diameter portion which has an axially continuous outer diameter approximately the same as that of the bottom, and in the second step, the other side is formed using the first inner mold and the outer mold, and the inside of the side formed in the first step is supported by a supporting inner mold having a convex portion protruding radially outward.

8. A method for manufacturing an expandable body as described in claim 2, characterized in that, prior to the first step, there is a step of expanding the base material into a spindle shape using a preform having a maximum outer diameter smaller than the inner diameter of the bottom of the first inner mold.

9. A method for manufacturing an expandable body as described in claim 2, characterized in that it includes a step prior to the first step of forming a plurality of first slits along the axial direction at a first axial end of the base material, and in the first step and the second step, the first end is expanded and the inner mold is inserted into the inside of the base material from the first end.

10. A method for manufacturing an expandable body as described in claim 9, characterized in that after the second step, a ring-shaped connecting portion, which is positioned at a second end portion opposite the first end portion of the base material and maintains the cylindrical shape of the second end portion, is separated from the base material.

11. A method for manufacturing an expandable body as described in claim 9 or 10, characterized in that it includes a step of forming a second slit along the axial direction at the second end and forming a regulating portion that regulates the expansion of the second slit.

12. A method for manufacturing an expansion body assembly, comprising the steps of: cutting out a cylindrical base material to form a plurality of struts extending in the axial direction of the base material and arranged in a circumferential direction surrounding the axial direction; forming a fixed portion having a second slit along the axial direction and a restricting portion that restricts the expansion of the second slit at a second end portion of the base material opposite to a first axial end portion of the base material; and forming a ring-shaped connecting portion that is connected to the fixed portion and maintains the cylindrical shape of the fixed portion by radially deforming the plurality of struts of the base material using a mold to form an expansion body having a waist portion whose outer diameter decreases midway in the axial direction; after forming the expansion body, separating the ring-shaped connecting portion from the fixed portion and releasing the restriction of the restricting portion to expand the second slit; inserting a long shaft portion into the expansion body; and after covering the tip portion of the shaft portion with the second end portion, restricting the expansion of the second slit with the restricting portion and fixing the second end portion to the tip portion of the shaft portion.

13. An expansion body formed by a plurality of struts extending along an axial direction and arranged in a circumferential direction surrounding the axial direction; and a long shaft portion connected to a base end of the expansion body, wherein the base end of the expansion body has a tubular fixing portion having at least one base end slit formed along the axial direction and capable of opening and closing the slit, one of two edges sandwiching the base end slit of the fixing portion is formed with a convex portion protruding in the circumferential direction toward the other edge, and the other edge is formed with a concave portion cut out so that the convex portion fits into it, and the base end slit is formed so as to include the boundary between the convex portion and the concave portion, the convex portion has a base portion formed at one end in the circumferential direction and an apex portion formed at the other end in the circumferential direction and having a longer length in the axial direction of the expansion body than the base portion, the concave portion has an open apex portion that receives the base portion of the convex portion, and an open bottom portion that is connected to the open apex portion and receives the apex of the convex portion, and the circumferential length of the apex portion is shorter than the circumferential length of the open bottom portion, A medical device characterized in that the base end of the expansion body is fixed to the shaft portion with the convex portion fitted into the concave portion and a circumferential gap formed between the top of the convex portion and the opening bottom of the concave portion.

14. The medical device according to claim 13, characterized in that the base end of the fixing part has a cut mark where the ring-shaped connecting part has been cut.

15. The medical device according to claim 14, characterized in that the base end of the fixing portion is recessed toward the tip of the expandable body and has a recess within which the cut mark portion is disposed.

16. The medical device of claim 13, characterized in that the plurality of struts include multiple sets of strut groups extending toward the base end of the expandable body, the fixing portion has at least one separation portion circumferentially separated by the base end slit, and each of the separation portions is connected to a respective base end of the strut group.

17. The medical device described in claim 13, characterized in that the distal end portions of the plurality of struts have a plurality of distal struts extending in the axial direction and independent of one another in the circumferential direction, and the distal end portion of the expandable body has a distal shaft portion that fixes the plurality of distal struts so that adjacent two of the plurality of distal struts do not become separated from each other in the circumferential direction.

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