catheter

Abstract

To provide a catheter which is capable of easily preventing a wall of the body cavity from being damaged while transported to a treatment part, and of easily improving passability in the body cavity.SOLUTION: A catheter 1 has: a first member 10 which has a distal end 10d and a proximal end 10p and is provided with a lumen extending in a longitudinal direction x; a bag-shaped body 30 which is provided at a distal part of the first member, is formed into an annular shape, and has an outer surface, an inner surface and an interior space; and a second member 20 which is placed in the bag-shaped interior space and is movable in the longitudinal direction x relative to the first member. In the bag body, a shortest distance from the outer surface to the inner surface is shorter than a shortest distance from the outer surface to the inner surface of the first member in a natural state that no external force is given to the bag-shaped body 30.SELECTED DRAWING: Figure 2

Description

【Technical Field】 【0001】 The present invention relates to a catheter. 【Background Art】 【0002】 When transporting medical instruments such as balloons and stents to a treatment site which is the target of treatment, for example, a resin tube is used. Specifically, the medical instrument is inserted into a body cavity such as a blood vessel in a state where it is arranged in the lumen of the resin tube and is carried to the treatment site. When the resin tube used at this time has a simple cylindrical shape, there are problems that the tip portion thereof hits the wall of the body cavity, damaging the wall of the body cavity and deteriorating the permeability. 【0003】 Patent Document 1 describes a catheter that can hardly damage the wall of a body cavity. The catheter has a long elastic tube-like component having at least one lumen. A soft and deformable tip component is attached to the distal end of the catheter, and the tip component has an outer diameter that expands and a contact area that increases by being pressed against a relatively stationary surface. It is described that this can reduce the pressure or force per unit area applied to the tissue. 【0004】 Patent Document 2 describes an instrument for medical technology with good operability. The instrument has a vertically long variable internal body, a vertically long outer coating body that at least fragmentarily surrounds the internal body on the circumferential side, and a device for transitioning the instrument from a variable state to a rigid state and vice versa. The internal body is formed in the form of a double tube having an inner tube that constitutes the inner wall and an outer tube that constitutes the outer wall and concentrically surrounds the inner tube. The device for transitioning the instrument from a variable state to a rigid state and vice versa increases the pressure in the annular gap to expand the outer tube in the radial direction, thereby applying pressure to the coating body to make the instrument rigid, and it is described that the operation is easy. It is also described that the outer diameter of the double tube of the internal body increases, but the internal space of the internal body remains fixed in size. [Prior art documents] [Patent Documents] 【0005】 [Patent Document 1] Japanese Patent Application Publication No. 60-040069 [Patent Document 2] Special Publication No. 2009-505700 [Overview of the project] [Problems that the invention aims to solve] 【0006】 However, the catheter described in Patent Document 1 prevents damage to the body cavity by expanding the outer diameter of the tip component. With the configuration of the catheter described in Patent Document 1, the expanded tip portion is prone to getting caught on the wall of the body cavity, and the problem of poor passage through the body cavity could not be solved. 【0007】 The medical device described in Patent Document 2 also improves operability by creating a rigid state through the application of pressure to expand its outer diameter. However, the expanded portion tends to catch on the walls of the body cavity, and there is still room for improvement in terms of improving passage through the body cavity. 【0008】 Furthermore, in both the catheter described in Patent Document 1 and the medical device described in Patent Document 2, it was necessary to ensure an inner diameter large enough for the medical device to pass through, in order to transport the medical device, such as a balloon or stent, to the treatment area and then place the medical device on the treatment area. 【0009】 The present invention has been made in view of the above circumstances, and its object is to provide a catheter that can easily prevent damage to the wall of the body cavity when transported to the treatment site, and can also easily improve passability within the body cavity. [Means for solving the problem] 【0010】 One embodiment of the catheter of the present invention that solves the above problems comprises: a first member having a distal end and a proximal end and a lumen extending in the longitudinal direction; a bag-like body provided at the distal end of the first member, formed in an annular shape and having an outer surface, an inner surface and an internal space; and a second member disposed in the internal space of the bag-like body and movable in the longitudinal direction relative to the first member, wherein in a natural state where no external force is applied to the bag-like body, the shortest distance from the outer surface to the inner surface is smaller than the shortest distance from the outer surface to the inner surface of the first member; and in a natural state where no external force is applied to the second member, the longitudinal direction is perpendicular to the central axis in the extending direction of the first member. The gist of this invention is that the distal portion of the second member has a reduced section in which the smallest circle in contact with the surface of the second member in a straight cross-section has a diameter smaller than the outer diameter of the bag-like body, and in a state where the reduced section of the second member is located inside the bag-like body, at least a portion of the surface on the internal space side of the bag-like body is in contact with the surface of the second member in the reduced section, and the minimum inner diameter of the bag-like body when the distal end of the second member is located distal to the proximal end of the bag-like body and at least a portion of the surface on the internal space side of the bag-like body is in contact with the surface of the second member in the reduced section is smaller than the minimum inner diameter of the bag-like body when the distal end of the second member is located at a second point which is proximal to the first point. First, the catheter with the distal end of the second member located at the first point is transported to the treatment area. Because the distal end of the second member is located at the first point, the inner diameter of the bag-like body is small. The small inner diameter of the bag-like structure makes it less likely for the catheter to come into contact with the body cavity wall when transporting it to the treatment site, thus reducing the risk of damaging the body cavity wall and preventing the catheter from getting caught on the body cavity wall. Furthermore, after the catheter reaches the treatment site, by positioning the distal end of the second component proximal to the first point, the minimum inner diameter of the bag-like structure becomes larger than the minimum inner diameter of the bag-like structure when the distal end of the second component is at the first point. As a result, when medical devices such as balloons, stents, baskets, and needles are placed in the lumen of the first component and transported to the treatment site, it becomes easier to protrude the medical devices from the bag-like structure. 【0011】 In the catheter of the present invention, it is preferable that the first member has a wall forming a lumen, and that an insertion passage is formed within the wall of the first member through which the second member is inserted. 【0012】 In the catheter of the present invention, the first member preferably comprises an outer cylinder and an inner cylinder disposed within the lumen of the outer cylinder, and the insertion passage is a space partitioned by the inner surface of the outer cylinder and the outer surface of the inner cylinder. 【0013】 In the catheter of the present invention, it is preferable that the internal space is in communication with the insertion passage. 【0014】 In the catheter of the present invention, it is preferable that the internal space does not communicate with the lumen of the first member. 【0015】 In the catheter of the present invention, it is preferable that the length from the distal end to the proximal end of the bag-like body when the reduced section of the second member is positioned within the internal space of the bag-like body is longer than the length from the distal end to the proximal end of the bag-like body when the reduced section of the second member is not positioned within the internal space of the bag-like body. 【0016】 In the catheter of the present invention, it is preferable that the catheter further includes a movement suppression mechanism that suppresses the longitudinal movement of the first member and the second member when the length from the distal end to the proximal end of the bag-like body when the reduced section of the second member is positioned in the internal space of the bag-like body is longer than the length from the distal end to the proximal end of the bag-like body when the reduced section of the second member is not positioned in the internal space of the bag-like body. 【0017】 In the catheter of the present invention, it is preferable that the stiffness of the second member in the direction perpendicular to the longitudinal direction in the reduced section is the same as or lower than the stiffness of the second member in the direction perpendicular to the longitudinal direction proximal to the reduced section. 【0018】 In the catheter of the present invention, it is preferable that at least one of the regions in the first member from the proximal end of the sac-like body to 10 cm proximal, and the region in the second member from the proximal end of the reduced section to 10 cm proximal, has a radiopaque portion. 【0019】 In the catheter of the present invention, it is preferable that the number of radiopaque portions arranged in the region from the proximal end of the sac-like body of the first member to 10 cm proximal is greater than the number of radiopaque portions arranged in the region from the proximal end of the reduced section of the second member to 10 cm proximal. 【0020】 In the catheter of the present invention, at least a bag-like body is provided with a first shape memory member, the elasticity of the first shape memory member is higher than that of the bag-like body, and in a natural state where no external force is applied to the first shape memory member, the diameter of the smallest circle that contacts the surface of the first shape memory member in a cross section perpendicular to the longitudinal direction centered on the central axis in the extending direction of the first member is preferably larger than the smallest inner diameter of the bag-like body when the contracted section of the second member is in contact with the surface on the internal space side of the bag-like body. 【0021】 In the catheter of the present invention, at least the reduced portion of the second member has a second shape memory portion, and it is preferable that the diameter of the smallest circle tangent to the surface of the second shape memory portion in a cross section perpendicular to the longitudinal direction centered on the central axis in the extending direction of the first member, in a natural state where no external force is applied to the second shape memory portion, is smaller than the diameter of the smallest circle tangent to the surface of the second member in a cross section perpendicular to the longitudinal direction centered on the central axis in the extending direction of the first member. 【0022】 In the catheter of the present invention, it is preferable that the second member has a lumen that extends in the longitudinal direction. 【0023】 In the catheter of the present invention, it is preferable that a linear member is provided, and that the linear member is fixed to the proximal portion of the second member. 【0024】 In the catheter of the present invention, it is preferable that the first member has a first diameter-reducing region at the proximal portion of the first member, the radial length of which becomes shorter toward the proximal side when observed from a direction perpendicular to the longitudinal direction. 【0025】 In the catheter of the present invention, a linear member is provided on the proximal side of the second member, and it is preferable that the linear member is fixed to the second member on the distal side of the proximal end of the first diameter-reducing region. 【0026】 In the catheter of the present invention, it further has a tubular member whose maximum outer diameter is smaller than that of the first member, the distal portion of the tubular member is fixed to the proximal portion of the first diameter-reducing region, and it is preferable that the linear member is disposed in the lumen of the tubular member. 【0027】 In the catheter of the present invention, it is preferable that the second member has a second diameter-reducing region at the proximal portion of the second member, the radial length of which becomes shorter toward the proximal side when observed from a direction perpendicular to the longitudinal direction. 【0028】 In the catheter of the present invention, it is preferable to include a shaft disposed movably with respect to the first member in the lumen of the first member, and an expansion member provided at the distal portion of the shaft and expanding in the radial direction. 【0029】 In the catheter of the present invention, it is preferable to further include a control mechanism for suppressing the longitudinal movement of the shaft in the lumen of the first member. 【0030】 In the catheter of the present invention, it is preferable that the expansion member is a balloon or a stent having a coating layer formed on its outer surface. 【0031】 In the catheter of the present invention, it is preferable that the coating layer contains a physiologically active agent. 【Effects of the Invention】 【0032】 The catheter of the present invention facilitates the protrusion of medical devices such as balloons, stents, baskets, and needles to the treatment site, helps prevent damage to the body cavity wall during transport to the treatment site, and improves passability within the body cavity. [Brief explanation of the drawing] 【0033】 [Figure 1] This is a side view showing an example of a catheter according to an embodiment of the present invention. [Figure 2] Figure 1 shows a cross-sectional view of the catheter parallel to its longitudinal direction, representing the state where the distal end of the second member is located at point 1. [Figure 3] Figure 1 shows a side view of the second component in its natural state in the catheter. [Figure 4] This shows a cross-sectional view of the second member at line IV-IV, as shown in Figure 3. [Figure 5] This shows a side view of a modified example of the second member shown in Figure 3. [Figure 6] Figure 5 shows a cross-sectional view of the second member from VI to VI. [Figure 7] Figure 2 shows a cross-sectional view of the catheter from point VII to VII. [Figure 8] Figure 1 shows a cross-sectional view of the catheter parallel to its longitudinal direction, representing the state where the distal end of the second member is located at the second point. [Figure 9] This shows a cross-sectional view parallel to the longitudinal direction of a catheter according to another embodiment of the present invention. [Modes for carrying out the invention] 【0034】 The present invention will be described in more detail below based on the embodiments described below. However, the present invention is not limited by the embodiments described below, and it is certainly possible to implement it with appropriate modifications within the scope that is consistent with the spirit of the preceding and following descriptions, and all such modifications are included within the technical scope of the present invention. In addition, hatching and component reference numerals may be omitted in the drawings for convenience, in which case please refer to the specification or other drawings. Furthermore, the dimensions of various components in the drawings may differ from the actual dimensions, as priority has been given to helping to understand the features of the present invention. 【0035】 One embodiment of the catheter of the present invention comprises a first member having a distal end and a proximal end and a lumen extending in the longitudinal direction; a bag-like body provided at the distal end of the first member, formed in an annular shape and having an outer surface, an inner surface and an internal space; and a second member disposed in the internal space of the bag-like body and movable in the longitudinal direction relative to the first member, wherein in a natural state where no external force is applied to the bag-like body, the shortest distance from the outer surface to the inner surface is smaller than the shortest distance from the outer surface to the inner surface of the first member; and in a natural state where no external force is applied to the second member, the cross section perpendicular to the longitudinal direction centered on the central axis in the extending direction of the first member. The gist of this invention is that the second member has a reduced section at its distal end in which the diameter of the smallest circle in contact with the surface of the second member is smaller than the outer diameter of the bag-like body, and in a state in which the reduced section of the second member is located inside the bag-like body, at least a portion of the surface on the internal space side of the bag-like body is in contact with the surface of the second member in the reduced section, and the minimum inner diameter of the bag-like body in a state in which the distal end of the second member is located distal to the proximal end of the bag-like body and at least a portion of the surface on the internal space side of the bag-like body is in contact with the surface of the second member in the reduced section is smaller than the minimum inner diameter of the bag-like body in a state in which the distal end of the second member is located at a second point which is proximal to the first point. 【0036】 The overall configuration of a catheter according to an embodiment of the present invention will be described with reference to Figures 1 to 9. Figures 1, 2, 8, and 9 show a catheter 1 having a first member 10 and a second member 20. In these drawings, the longitudinal direction of the first member 10 is indicated by x and the radial direction by y. The radial direction y is perpendicular to the longitudinal direction x, but here only the one direction perpendicular to the longitudinal direction x is shown. 【0037】 In this specification, the proximal side refers to the side of the first member 10 that is closer to the user's hand in the direction of extension, and the distal side refers to the opposite side of the proximal side, i.e., the side being treated. Furthermore, the distal portion of each member refers to the distal half of each member, and the proximal portion of each member refers to the proximal half of each member. 【0038】 Figure 1 is a side view showing an example of a catheter 1 according to an embodiment of the present invention, and Figure 2 is a cross-sectional view of the catheter 1 parallel to the longitudinal direction x, showing the state in which the distal end 20d of the second member 20 is located at the first point P1. 【0039】 As shown in Figures 1 and 2, the catheter 1 comprises a first member 10, a sac-like body 30, and a second member 20. The first member 10 has a distal end 10d and a proximal end 10p, and has a lumen extending in the longitudinal direction x. 【0040】 It is preferable that the first member 10 is flexible. The flexibility of the first member 10 allows it to deform to conform to the shape of the body cavity when inserted into the body. Furthermore, it is preferable that the first member 10 is elastic. The elasticity of the first member 10 allows it to maintain its shape even when deformed to conform to the shape of the body cavity, making it less likely for the lumen of the first member 10 to collapse. 【0041】 Examples of the first member 10 include a hollow body formed by arranging one or more wires in a predetermined pattern, a hollow body with at least one of its inner or outer surfaces coated with resin, a resin tube, and a connection of these in the longitudinal direction x. Examples of a hollow body in which wires are arranged in a predetermined pattern include a cylindrical body having a mesh structure formed by simply crossing or weaving wires, or by cutting out a tube made of a metal tube or polymer material with a laser, and a coil in which wires are wound. The wires may be one or more single wires or one or more stranded wires. The resin tube can be manufactured, for example, by extrusion molding. Among these, the first member 10 is preferably a resin tube. By making the first member 10 a resin tube, it becomes easier to make the first member 10 which has excellent flexibility and elasticity. 【0042】 If the first member 10 is a resin tube, the first member 10 can be composed of a single layer or multiple layers. The first member 10 may be composed of a single layer in part in the longitudinal direction x or in the circumferential direction, and the other part may be composed of multiple layers. 【0043】 As materials for the first member 10, for example, synthetic resins such as polyolefin resins like polyethylene and polypropylene, polyamide resins like nylon, polyester resins like PET, aromatic polyether ketone resins like PEEK, polyether polyamide resins, polyurethane resins, polyimide resins, fluororesins like PTFE, PFA, and ETFE, and metals such as stainless steel, carbon steel, and nickel-titanium alloys can be used. These may be used individually or in combination of two or more. 【0044】 It is preferable that the outer surface of the first member 10 is coated with a hydrophilic polymer. By coating the outer surface of the first member 10 with a hydrophilic polymer, the slipperiness of the outer surface of the first member 10 is improved, resulting in a catheter 1 that is easy to insert. 【0045】 Examples of hydrophilic polymers include poly-2-hydroxyethyl methacrylate, polyacrylamide, polyvinylpyrrolidone, and maleic anhydride copolymers such as methyl vinyl ether maleic anhydride copolymers. 【0046】 It is preferable that the inner surface of the first member 10 has a layer containing at least one of a fluororesin and a polyolefin resin. Only a part of the inner surface of the first member 10 may be made of fluororesin or polyolefin resin, or the entire inner surface of the first member 10 may be made of fluororesin or polyolefin resin. By having a layer containing at least one of a fluororesin and a polyolefin resin on the inner surface of the first member 10, the sliding properties of the inner surface of the first member 10 are improved, making it easier to move and release members placed in the lumen of the first member 10. 【0047】 To provide the first member 10 with a layer on its inner surface containing at least one of a fluororesin and a polyolefin resin, examples include providing the first member 10 with a multilayer structure and using at least one of a fluororesin and a polyolefin resin as the material constituting the innermost layer, or applying a coating to the inner surface of the first member 10 containing at least one of a fluororesin and a polyolefin resin. 【0048】 The length of the longitudinal direction x of the first member 10 can be selected to be an appropriate length depending on the length of the longitudinal direction x of the second member 20 which is positioned outside the lumen of the first member 10, or the length of the longitudinal direction x of the article which is positioned inside the lumen of the first member 10. For example, the length of the longitudinal direction x of the first member 10 can be 30 mm or more and 700 mm or less. 【0049】 The outer diameter of the first member 10 can be appropriately selected as needed. For example, the outer diameter of the first member 10 can be 1 mm or more and 5 mm or less, and preferably 2 mm or less. By setting the outer diameter of the first member 10 within the above range, the outer diameter of the first member 10 can be kept small. 【0050】 As shown in Figures 2 and 7, the bag-like body 30 is provided on the distal part of the first member 10, is formed in an annular shape, and has an outer surface 30A, an inner surface 30B, and an internal space 30C. The bag-like body 30 is an annular bag-shaped member and has a portion whose outer diameter is smaller than that of the first member 10. It is preferable that the bag-like body 30 has an annular shape when viewed from the longitudinal direction x. 【0051】 The material used to constitute the bag-like body 30 can be the same synthetic resin, metal, or the like used for the first member 10. 【0052】 As shown in Figure 2, the proximal portion of the bag-like body 30 may be connected to the distal portion of the first member 10, or the proximal end 30p of the bag-like body 30 may be connected to the distal end 10d of the first member 10. 【0053】 In a natural state where no external force is applied to the bag-like body 30, the shortest distance from the outer surface 30A to the inner surface 30B of the bag-like body 30 is smaller than the shortest distance from the outer surface to the inner surface of the first member 10. Because the shortest distance from the outer surface 30A to the inner surface 30B of the bag-like body 30 is smaller than the shortest distance from the outer surface to the inner surface of the first member 10, the outer diameter of the distal end of the catheter 1 can be reduced, and the ease of insertion of the catheter 1 can be improved. 【0054】 In the bag-like body 30, the portion where the shortest distance from the outer surface 30A to the inner surface 30B is smaller than the shortest distance from the outer surface to the inner surface of the first member 10 is preferably located at the distal end of the bag-like body 30, more preferably at the distal end 30d of the bag-like body 30. This configuration of the bag-like body 30 makes it easier to maintain a small outer diameter, especially on the distal side, thus reducing the likelihood of snagging on the body cavity wall and preventing the catheter 1 from damaging the body cavity wall during transport to the treatment area. Furthermore, it also improves the passability of the catheter 1 within the body cavity. 【0055】 The bag-like body 30 is formed in an annular shape, but for example, the bag-like body 30 may have a hollow frustoconical shape. The bag-like body 30 is formed in an annular shape and may have an internal space 30C that communicates with the outside of the bag-like body 30. 【0056】 As shown in Figures 2 and 7, the internal space 30C is a space formed within the wall of the annular bag-like body 30. More specifically, the internal space 30C is a space formed within the wall that forms the lumen of the bag-like body 30. It is preferable that the internal space 30C exists throughout the entire circumferential direction within the wall of the bag-like body 30. Although not shown, the internal space 30C may exist only in a part of the circumferential direction within the wall of the bag-like body 30. 【0057】 Preferably, the shortest distance from the outer surface 30A to the inner surface 30B at the distal end 30d of the bag-shaped body 30 is smaller than the shortest distance from the outer surface 30A to the inner surface 30B at the proximal end 30p of the bag-shaped body 30. By making the shortest distance from the outer surface 30A to the inner surface 30B at the distal end 30d of the bag-shaped body 30 smaller than the shortest distance from the outer surface 30A to the inner surface 30B at the proximal end 30p of the bag-shaped body 30, the rigidity of the distal side of the bag-shaped body 30 becomes lower than the rigidity of the proximal side of the bag-shaped body 30, making it easier to change the minimum inner diameter of the bag-shaped body 30 by contact between the second member 20 and the bag-shaped body 30. 【0058】 The thickness of the proximal end 30p of the bag-like body 30 can be selected appropriately according to the thickness of the distal end 10d of the first member 10, etc. The thickness of the proximal end 30p of the bag-like body 30 can be about the same as the thickness of the distal end 11d of the first member 10, for example, it can be 0.01 mm or more and 0.5 mm or less. 【0059】 The bag-like body 30 is preferably tapered, narrowing from the proximal to the distal end. The tapered shape of the bag-like body 30 allows for a smaller outer diameter at the distal end of the catheter 1, thereby improving the ease of insertion of the catheter 1. 【0060】 As shown in Figure 2, the second member 20 is positioned outside the lumen of the first member 10 and is movable in the longitudinal direction x relative to the first member 10. 【0061】 Figure 3 is a side view of the second member 20 in its natural state, and Figure 4 is a cross-sectional view of the second member 20 shown in Figure 3, perpendicular to the longitudinal direction x. Furthermore, Figure 5 is a modified example of the second member 20 shown in Figure 3, and is a side view of the second member 20 in its natural state, and Figure 6 is a cross-sectional view of the second member 20 shown in Figure 5, perpendicular to the longitudinal direction x. 【0062】 As shown in Figures 3 to 6, in a natural state where no external force is applied to the second member 20, the second member 20 has a reduced section 21 in its distal portion where the diameter of the smallest circle C1 tangent to the surface of the second member 20 in a cross section perpendicular to the longitudinal direction x centered on the central axis in the extending direction of the first member 10 is smaller than the outer diameter of the bag-like body 30. 【0063】 Examples of the second member 20 include a cylindrical body as shown in Figures 3 and 4, a body formed from wires as shown in Figures 5 and 6, a hollow body formed by arranging one or more wires in a predetermined pattern, a hollow body with resin coated on at least one of its inner or outer surfaces, and a combination of these connected in the longitudinal direction x. As shown in Figures 5 and 6, when the second member 20 is composed of wires, the number of wires may be one or more. Examples of hollow bodies in which wires are arranged in a predetermined pattern include a cylindrical body having a mesh structure formed by simply crossing or weaving wires, or by cutting out a tube made of a metal tube or polymer material with a laser, and a coil in which wires are wound. The wires may be one or more single wires, or one or more stranded wires. 【0064】 As materials for the second member 20, for example, metals such as stainless steel, carbon steel, and nickel-titanium alloys; polyolefin resins such as polyethylene and polypropylene; polyamide resins such as nylon; polyester resins such as PET; aromatic polyether ketone resins such as PEEK; polyether polyamide resins; polyurethane resins; polyimide resins; and synthetic resins such as PTFE, PFA, and ETFE. These may be used individually or in combination of two or more. 【0065】 The length of the longitudinal direction x of the second member 20 can be selected to be an appropriate length depending on the length of the longitudinal direction x of the first member 10, etc. For example, the length of the longitudinal direction x of the second member 20 can be 15 mm or more and 600 mm or less. 【0066】 The outer diameter of the second member 20 can be appropriately selected depending on the outer diameter of the first member 10 that comes into contact with the second member 20, the outer diameter of the bag-like body 30, etc. For example, the outer diameter of the second member 20 can be 0.5 mm or more and 4.8 mm or less. The inner diameter of the second member 20 can also be appropriately selected. 【0067】 The thickness of the second member 20 can be selected to be an appropriate thickness, for example, 0.01 mm or more and 0.2 mm or less. The average thickness of the second member 20 can be, for example, 0.075 mm. 【0068】 Figure 7 is a cross-sectional view of the catheter 1 perpendicular to the longitudinal direction x. As shown in Figures 2 and 7, when the reduced section 21 of the second member 20 is positioned inside the bag-like body 30, at least a portion of the surface of the bag-like body 30 on the side of the internal space 30C is in contact with the surface of the second member 20 in the reduced section 21. 【0069】 Figure 8 is a cross-sectional view of catheter 1 parallel to the longitudinal direction x, showing the state in which the distal end 20d of the second member 20 is located at the second point P2. 【0070】 As shown in Figures 2 and 8, the minimum inner diameter of the bag-like body 30 when the distal end 20d of the second member 20 is located distal to the proximal end 30p of the bag-like body 30 and at least a portion of the surface on the internal space 30C side of the bag-like body 30 is in contact with the surface of the second member 20 in the reduced section 21 is smaller than the minimum inner diameter of the bag-like body 30 when the distal end 20d of the second member 20 is located at a second point P2 which is proximal to the first point P1. 【0071】 Since the minimum inner diameter of the bag-like body 30 when the distal end 20d of the second member 20 is located at the first point P1 is smaller than the minimum inner diameter of the bag-like body 30 when the distal end 20d of the second member 20 is located at the second point P2, the inner diameter of the bag-like body 30 can be reduced by moving the distal end 20d of the second member 20 to the first point P1, which is distal to the second point P2. 【0072】 First, the catheter 1 is transported to the treatment area with the distal end 20d of the second member 20 located at the first point P1. Because the distal end 20d of the second member 20 is located at the first point P1, the inner diameter of the bag-like body 30 becomes small. This small inner diameter makes it less likely for the catheter 1 to come into contact with the body cavity wall during transport to the treatment area, thus reducing the risk of damaging the body cavity wall. Furthermore, it also reduces the likelihood of the catheter 1 getting caught on the body cavity wall, thereby improving its passage through the body cavity. Additionally, after the catheter 1 reaches the treatment area, by positioning the distal end 20d of the second member 20 proximal to the first point P1, the inner diameter of the bag-like body 30 becomes larger than the minimum inner diameter when the distal end 20d of the second member 20 is located at the first point P1. As a result, when medical devices such as balloons, stents, baskets, and needles are placed in the lumen of the first member 10 and transported to the treatment area, the medical devices can be easily protruded from the opening at the distal end 30d of the bag-like body 30. 【0073】 The smallest inner diameter of the pouch-like body 30 is preferably located at the distal end 30d of the pouch-like body 30. In other words, the part with the smallest inner diameter of the pouch-like body 30 is preferably at the distal end 30d of the pouch-like body 30. By having the part with the smallest inner diameter of the pouch-like body 30 be at the distal end 30d of the pouch-like body 30, the outer diameter of the distal end of the catheter 1 becomes smaller, which improves the ease of insertion of the catheter 1. 【0074】 In the contracted section 21 of the second member 20 in its natural state, the diameter of the smallest circle C1 that contacts the surface of the second member 20 in a cross section perpendicular to the longitudinal direction x centered on the central axis in the extending direction of the first member 10 is preferably 98% or less, more preferably 95% or less, and even more preferably 93% or less of the maximum outer diameter of the bag-like body 30. By setting the upper limit of the ratio between the diameter of the smallest circle C1 that contacts the surface of the second member 20 and the maximum outer diameter of the bag-like body 30 to the above range, the distal end 20d of the second member 20 can come into contact with the surface on the internal space 30C side of the bag-like body 30, making it easier to sufficiently reduce the inner diameter of the bag-like body 30. The lower limit of the ratio between the diameter of the smallest circle C1 that contacts the surface of the second member 20 and the maximum outer diameter of the bag-like body 30 is not particularly limited, but can be, for example, 5% or more, 10% or more, or 15% or more. 【0075】 Although not shown in the figures, it is preferable to have a lubricating coating layer between the first member 10 and the second member 20. Having a lubricating coating layer between the first member 10 and the second member 20 allows for smooth movement of the second member 20 in the longitudinal direction x relative to the first member 10. Examples of materials constituting the lubricating coating layer include silicone, fluororesin, and polyolefin resin, with silicone being particularly suitable. 【0076】 When the distal end 20d of the second member 20 is located distal to the proximal end 30p of the bag-shaped body 30, the minimum inner diameter of the bag-shaped body 30 is preferably 30% or more, more preferably 35% or more, and even more preferably 40% or more of the inner diameter of the first member 10. By setting the lower limit of the ratio between the minimum inner diameter of the bag-shaped body 30 and the inner diameter of the first member 10 within the above range, it is possible to maintain a small minimum inner diameter of the bag-shaped body 30 while securing the lumen of the bag-shaped body 30, making it easier to insert an article such as a guide wire 120 into the inside of the bag-shaped body 30. Furthermore, when the distal end 20d of the second member 20 is located distal to the proximal end 30p of the bag-shaped body 30, the minimum inner diameter of the bag-shaped body 30 is preferably 70% or less, more preferably 65% ​​or less, and even more preferably 60% or less of the inner diameter of the first member 10. By setting the upper limit of the ratio between the minimum inner diameter of the bag-like body 30 and the inner diameter of the first member 10 to the above range, the minimum inner diameter of the bag-like body 30 tends to be sufficiently small compared to the first member 10. As a result, the bag-like body 30 becomes less likely to come into contact with the wall of the body cavity, etc., and the ease of insertion of the catheter 1 can be improved. 【0077】 When the distal end 20d of the second member 20 is located distal to the proximal end 30p of the bag-like body 30, the minimum inner diameter of the bag-like body 30 can be selected to be an appropriate size, for example, 0.3 mm or more and 2.0 mm or less. 【0078】 The minimum outer diameter of the bag-like body 30 when the distal end 20d of the second member 20 is located distal to the proximal end 30p of the bag-like body 30 can also be appropriately selected according to the minimum inner diameter of the bag-like body 30, etc. The minimum outer diameter of the bag-like body 30 when the distal end 20d of the second member 20 is located distal to the proximal end 30p of the bag-like body 30 can be, for example, 0.31 mm or more and 3.0 mm or less. 【0079】 When the distal end 20d of the second member 20 is located proximal to the proximal end 30p of the bag-like body 30, the minimum inner diameter of the bag-like body 30 can be selected to be an appropriate size depending on the inner diameter of the first member 10, etc. The minimum inner diameter of the bag-like body 30 when the distal end 20d of the second member 20 is located proximal to the proximal end 30p of the bag-like body 30 can be about the same as the inner diameter of the first member 10, for example, it can be 0.4 mm or more, 0.8 mm or more, 1.2 mm or more, or 4.0 mm or less. 【0080】 When the distal end 20d of the second member 20 is located proximal to the proximal end 30p of the bag-like body 30, the length x in the longitudinal direction of the bag-like body 30 can be appropriately selected, for example, to be between 1 mm and 20 mm. 【0081】 Figures 1, 2, and 8 show an example of a so-called rapid exchange type (RX type) configuration in which the guidewire 120 is inserted partway from the distal end to the proximal end of the shaft 90. In addition to the rapid exchange type, the catheter 1 of the present invention can also be applied to a so-called over-the-wire type (OTW type) in which the guidewire 120 is inserted from the distal end to the proximal end of the shaft 90. 【0082】 As shown in Figures 2 and 8, the first member 10 has a wall forming a lumen, and it is preferable that an insertion passage 14 through which the second member 20 is inserted is formed within the wall of the first member 10. Since the insertion passage 14 is formed within the wall of the first member 10, it is not necessary to provide a separate member to form a path for inserting the second member 20, and thus the diameter of the catheter 1 can be further reduced. 【0083】 As shown in Figures 2 and 8, the first member 10 has an outer cylinder 15 and an inner cylinder 16 disposed inside the lumen of the outer cylinder 15, and the insertion passage 14 may be a space partitioned by the inner surface of the outer cylinder 15 and the outer surface of the inner cylinder 16. By having the first member 10 have an outer cylinder 15 and an inner cylinder 16, it becomes unnecessary to provide a separate member for forming the insertion passage 14, and the catheter 1 can be made thinner. 【0084】 The thickness of the outer cylinder 15 can be, for example, 0.010 mm or more, 0.015 mm or more, or 0.020 mm or more. Alternatively, the thickness of the outer cylinder 15 can be, for example, 0.500 mm or less, 0.450 mm or less, or 0.400 mm or less. 【0085】 The thickness of the inner cylinder 16 can be, for example, 0.010 mm or more, 0.015 mm or more, or 0.020 mm or more. Alternatively, the thickness of the inner cylinder 16 can be, for example, 0.500 mm or less, 0.450 mm or less, or 0.400 mm or less. 【0086】 In a cross-section perpendicular to the longitudinal direction x, the distance between the inner surface of the outer cylinder 15 and the outer surface of the inner cylinder 16 is preferably 0.01 mm or more and 1.0 mm or less. By setting the distance between the inner surface of the outer cylinder 15 and the outer surface of the inner cylinder 16 within the above range, it is possible to ensure sufficient width of the insertion passage 14 while preventing the outer diameter of the first member 10 from becoming too large, and to enable smooth movement of the second member 20 in the longitudinal direction x. 【0087】 As shown in Figures 2 and 8, it is preferable that the internal space 30C of the bag-like body 30 is in communication with the insertion passage 14. The internal space 30C being in communication with the insertion passage 14 makes it easier to feed the second member 20, which is inserted through the insertion passage 14, into the internal space 30C of the bag-like body 30. 【0088】 As shown in Figures 2 and 8, it is preferable that the internal space 30C does not communicate with the lumen of the first member 10. It is also preferable that the internal space 30C does not communicate with the lumen of the bag-like body 30. By ensuring that the internal space 30C does not communicate with the lumen of the first member 10 or the lumen of the bag-like body 30, the movement of the second member 20 inserted into the internal space 30C can be facilitated, and the second member 20 can be prevented from unintentionally entering the lumen of the first member 10 or the lumen of the bag-like body 30. 【0089】 It is preferable that the length of the bag-shaped body 30 from its distal end 30d to its proximal end 30p when the reduced section 21 of the second member 20 is positioned in the internal space 30C of the bag-shaped body 30 is longer than the length of the bag-shaped body 30 from its distal end 30d to its proximal end 30p when the reduced section 21 of the second member 20 is not positioned in the internal space 30C of the bag-shaped body 30. Because the length of the bag-shaped body 30 when the reduced section 21 is positioned in the internal space 30C is longer than the length of the bag-shaped body 30 when the reduced section 21 is not positioned in the internal space 30C, the bag-shaped body 30 is stretched in the longitudinal direction x when the reduced section 21 is positioned in the internal space 30C. As a result, wrinkles are less likely to form in the bag-shaped body 30, the outer surface of the bag-shaped body 30 tends to be smoother, and a catheter 1 can be made that is less likely to catch on the wall of the body cavity. 【0090】 When the reduced section 21 of the second member 20 is positioned in the internal space 30C of the bag-shaped body 30, the length from the distal end 30d to the proximal end 30p of the bag-shaped body 30 is preferably 1.05 times or more, more preferably 1.1 times or more, and even more preferably 1.15 times or more, the length from the distal end 30d to the proximal end 30p of the bag-shaped body 30 when the reduced section 21 of the second member 20 is not positioned in the internal space 30C of the bag-shaped body 30. By setting the lower limit of the ratio between the length of the bag-shaped body 30 when the reduced section 21 is positioned in the internal space 30C and the length of the bag-shaped body 30 when the reduced section 21 is not positioned in the internal space 30C, it becomes easier to stretch out wrinkles that have formed in the bag-shaped body 30, which has been reduced in diameter due to the position of the reduced section 21 in the internal space 30C. Furthermore, the upper limit of the ratio between the length of the bag-like body 30 when the reduced section 21 is located in the internal space 30C and the length of the bag-like body 30 when the reduced section 21 is not located in the internal space 30C is not particularly limited, but for example, it can be 3 times or less, 2.5 times or less, or 2 times or less. 【0091】 It is preferable that the catheter 1 is further equipped with a movement-inhibiting mechanism that suppresses the movement of the first member 10 and the second member 20 in the longitudinal direction x when the length from the distal end 30d to the proximal end 30p of the bag-shaped body 30 is longer than the length from the distal end 30d to the proximal end 30p of the bag-shaped body 30 when the reduced section 21 of the second member 20 is positioned in the internal space 30C of the bag-shaped body 30. The presence of the movement-inhibiting mechanism in the catheter 1 makes it easier to maintain the stretched state of the bag-shaped body 30. Therefore, when the catheter 1 is delivered to the treatment area with the bag-shaped body 30 in a reduced diameter state, the outer surface of the bag-shaped body 30 can be kept smooth, making it less likely to get caught on the wall of the body cavity. 【0092】 The stiffness of the second member 20 in the direction perpendicular to the longitudinal direction x in the contracted section 21 is preferably the same as or lower than the stiffness of the second member 20 in the direction perpendicular to the longitudinal direction x in the area proximal to the contracted section 21. When the stiffness of the second member 20 in the contracted section 21 is the same as or lower than the stiffness of the second member 20 in the area proximal to the contracted section 21, the contracted section 21 expands more easily, and the second member 20 can be smoothly pulled towards the user. 【0093】 It is more preferable that the stiffness of the second member 20 in the direction perpendicular to the longitudinal direction x in the reduced section 21 is lower than the stiffness of the second member 20 in the direction perpendicular to the longitudinal direction x proximal to the reduced section 21. By having the stiffness of the second member 20 in the reduced section 21 lower than the stiffness of the second member 20 proximal to the reduced section 21, the reduced section 21 can be easily reduced in diameter when the distal end 20d of the second member 20 is positioned distal to the proximal end 30p of the bag-like body 30, and the inner diameter of the bag-like body 30 can be easily reduced. 【0094】 As shown in Figures 2 and 8, it is preferable that the radiopaque portion 40 is provided in at least one of the following regions: region A1 in the first member 10 from the proximal end 30p of the bag-shaped body 30 to 10 cm proximal, and region A2 in the second member 20 from the proximal end 21p of the reduced section 21 to 10 cm proximal. By providing a radiopaque portion 40 in at least one of region A1 and region A2, the position of the distal end of the catheter 1 can be visually confirmed using an X-ray imaging device. 【0095】 The X-ray opaque portion 40 is a portion containing an X-ray opaque material. Examples of X-ray opaque materials include at least one selected from the group consisting of lead, barium, iodine, tungsten, gold, platinum, iridium, stainless steel, titanium, cobalt-chromium alloy, etc. 【0096】 The radiopaque portion 40 may include a portion formed from an X-ray opaque substance, or a portion formed by kneading an X-ray opaque substance into a material such as a synthetic resin. In particular, it is preferable that the radiopaque portion 40 is formed by an X-ray opaque marker containing an X-ray opaque substance. Because the radiopaque portion 40 is an X-ray opaque marker, it is possible to accurately form the radiopaque portion 40 at the desired position during the manufacture of the catheter 1. 【0097】 The shape of the X-ray opaque marker that forms the X-ray opaque area 40 can be cylindrical, polygonal, C-shaped with a notch in the tube, or a coil shape formed by winding a wire. Among these, the shape of the X-ray opaque marker is preferably cylindrical. The cylindrical shape of the X-ray opaque marker improves the visibility of the X-ray opaque area 40 by the X-ray imaging device. 【0098】 The number of radiopaque portions 40 located in region A1 of the bag-shaped body 30 in the first member 10, from the proximal end 30p to 10 cm proximal, may be one or multiple. Similarly, the number of radiopaque portions 40 located in region A2 of the reduced section 21 in the second member 20, from the proximal end 21p to 10 cm proximal, may also be one or multiple. 【0099】 It is preferable that the radiopaque portion 40 is located in region A1, which extends 10 cm proximal to the proximal end 30p of the bag-shaped body 30 in the first member 10, and in region A2, which extends 10 cm proximal to the proximal end 21p of the reduced section 21 in the second member 20. In other words, it is preferable that the radiopaque portion 40 is located in both region A1 and region A2. By having the radiopaque portion 40 in both region A1 and region A2, the position of the distal ends of both the first member 10 and the second member 20 can be confirmed by the X-ray imaging device, making the procedure easier to perform. 【0100】 As shown in Figures 2 and 8, it is preferable that the number of radiopaque portions 40 located in region A1 of the first member 10, from the proximal end 30p of the bag-shaped body 30 to 10 cm proximal, is greater than the number of radiopaque portions 40 located in region A2 of the second member 20, from the proximal end 21p of the reduced section 21 to 10 cm proximal. Having more radiopaque portions 40 in region A1 than in region A2 makes it easier to confirm the position of the distal end of the catheter 1 using an X-ray imaging device. 【0101】 As shown in Figures 2 and 8, at least the bag-shaped body 30 is provided with a first shape memory member 51, and the elasticity of the first shape memory member 51 is higher than that of the bag-shaped body 30. Preferably, in a natural state where no external force is applied to the first shape memory member 51, the diameter of the smallest circle that contacts the surface of the first shape memory member 51 in a cross section perpendicular to the longitudinal direction x centered on the central axis in the extending direction of the first member 10 is larger than the smallest inner diameter of the bag-shaped body 30 when the contracted section 21 of the second member 20 is in contact with the surface on the internal space 30C side of the bag-shaped body 30. Here, elasticity refers to the magnitude of strain at the elastic limit, and high elasticity means that even if a large strain is applied, it returns to its original shape and has a large restoring force. The first shape memory member 51 has higher elasticity than the bag-shaped body 30, and even if an external force is applied to the first shape memory member 51 and it is deformed, it easily returns to the shape of the first shape memory member 51 in its natural state once the external force applied to the first shape memory member 51 is removed. Because the first shape memory member 51 is provided at least on the bag-shaped body 30, as the distal end 20d of the second member 20 moves proximal to the proximal end 30p of the bag-shaped body 30, the first shape memory member 51 makes it easier for the bag-shaped body 30 to expand in diameter, making it easier to open the bag-shaped body 30. 【0102】 Examples of materials that constitute the first shape memory member 51 include stainless steel such as SUS304 and SUS316, shape memory alloys such as Ni-Ti alloys, and shape memory resins. Among these, the material constituting the first shape memory member 51 is preferably a shape memory alloy, and more preferably a Ni-Ti alloy. By using a Ni-Ti alloy as the material constituting the first shape memory member 51, the first shape memory member 51 exhibits excellent shape memory properties and elasticity. 【0103】 The first shape memory member 51 is provided at least on the bag-shaped body 30. Specifically, for example, the first shape memory member 51 can be provided on the surface of the bag-shaped body 30 facing the inner lumen side of the first member 10, inside the wall forming the bag-shaped body 30, or on the inner surface of the bag-shaped body 30. 【0104】 In a natural state where no external force is applied to the first shape memory member 51, the diameter of the smallest circle tangent to the surface of the first shape memory member 51 in a cross section perpendicular to the longitudinal direction x centered on the central axis in the extending direction of the first member 10 is preferably 1.1 times or more, more preferably 1.2 times or more, and even more preferably 1.3 times or more, the smallest inner diameter of the bag-shaped body 30. By setting the lower limit of the ratio between the diameter of the smallest circle tangent to the surface of the first shape memory member 51 in a natural state and the smallest inner diameter of the bag-shaped body 30 within the above range, the bag-shaped body 30 can be easily expanded in diameter by the first shape memory member 51. Furthermore, in a natural state where no external force is applied to the first shape memory member 51, the diameter of the smallest circle tangent to the surface of the first shape memory member 51 in a cross section perpendicular to the longitudinal direction x centered on the central axis in the extending direction of the first member 10 is preferably 100 times or less, more preferably 90 times or less, and even more preferably 80 times or less, the smallest inner diameter of the bag-shaped body 30. By setting the upper limit of the ratio between the diameter of the smallest circle in contact with the surface of the first shape memory member 51 in its natural state and the minimum inner diameter of the bag-like body 30 to the above range, it is possible to reduce the diameter of the smallest circle in contact with the surface of the first shape memory member 51 when an external force is applied to the first shape memory member 51, thereby preventing the outer diameter of the catheter 1 from becoming too large. 【0105】 It is preferable that the first shape memory member 51 is provided across both the bag-shaped body 30 and the first member 10. By providing the first shape memory member 51 on both the bag-shaped body 30 and the first member 10, when an external force is applied to the first shape memory member 51 to deform it and then the external force is removed from the first shape memory member 51, the first shape memory member 51 is more likely to return to its original shape, making it easier to expand the diameter of the bag-shaped body 30. 【0106】 As shown in Figures 2 and 8, at least the reduced section 21 of the second member 20 has a second shape memory section 52, and it is preferable that the diameter of the smallest circle tangent to the surface of the second shape memory section 52 in a cross section perpendicular to the longitudinal direction x centered on the central axis in the extending direction of the first member 10, in a natural state where no external force is applied to the second shape memory section 52, is smaller than the diameter of the smallest circle tangent to the surface of the second member 20 in a cross section perpendicular to the longitudinal direction x centered on the central axis in the extending direction of the first member 10. The second shape memory section 52 is such that even if it is deformed by applying an external force, it easily returns to its natural shape when the external force applied to the second shape memory section 52 is removed. Because at least the reduced section 21 of the second member 20 has the second shape memory section 52, the second shape memory section 52 makes it easier to reduce the diameter of the smallest circle that is in contact with the surface of the second member 20 in a cross section perpendicular to the longitudinal direction x, centered on the central axis in the extending direction of the first member 10 in its natural state. Therefore, the reduced section 21 of the second member 20 makes it easier to reduce the diameter of the bag-like body 30. 【0107】 The second shape memory section 52 is provided in at least the reduced section 21 of the second member 20 and may be a separate member from the second member 20, or it may be at least a part of the second member 20. The entire second member 20 may also be the second shape memory section 52. 【0108】 Examples of materials that constitute the second shape memory section 52 include stainless steel such as SUS304 and SUS316, shape memory alloys such as Ni-Ti alloys, and shape memory resins. Among these, the material constituting the second shape memory section 52 is preferably a shape memory alloy, and more preferably a Ni-Ti alloy. By using a Ni-Ti alloy as the material constituting the second shape memory section 52, it is possible to obtain a second shape memory section 52 with excellent shape memory properties and elasticity. 【0109】 In a natural state where no external force is applied to the second shape memory section 52, the diameter of the smallest circle that contacts the surface of the second shape memory section 52 in a cross section perpendicular to the longitudinal direction x centered on the central axis in the extending direction of the first member 10 is preferably 99% or less, more preferably 97% or less, and even more preferably 95% or less of the diameter of the smallest circle that contacts the surface of the second member 20 in a cross section perpendicular to the longitudinal direction x centered on the central axis in the extending direction of the first member 10. By setting the upper limit of the ratio between the diameter of the smallest circle that contacts the surface of the second shape memory section 52 in a natural state and the diameter of the smallest circle that contacts the surface of the second member 20 within the above range, it is possible to make it easier to reduce the diameter of the smallest circle that contacts the surface of the second member 20 in a natural state. Furthermore, in a natural state where no external force is applied to the second shape memory section 52, the diameter of the smallest circle that contacts the surface of the second shape memory section 52 in a cross section perpendicular to the longitudinal direction x centered on the central axis in the extending direction of the first member 10 is preferably 1% or more, more preferably 3% or more, and even more preferably 5% or more of the diameter of the smallest circle that contacts the surface of the second member 20 in a cross section perpendicular to the longitudinal direction x centered on the central axis in the extending direction of the first member 10. By setting the lower limit of the ratio between the diameter of the smallest circle that contacts the surface of the second shape memory section 52 in a natural state and the diameter of the smallest circle that contacts the surface of the second member 20 within the above range, the diameter of the smallest circle that contacts the surface of the second shape memory section 52 does not become too small, making it easier to smoothly move the second member 20 in the longitudinal direction x relative to the first member 10. 【0110】 As shown in Figures 2 and 8, the second member 20 preferably has a lumen extending in the longitudinal direction x. That is, as shown in Figures 3 and 4, the second member 20 preferably has a cylindrical shape. By having a lumen in the second member 20, the contact area between the surface of the second member 20 and the surface of the bag-like body 30 can be increased. 【0111】 If the second member 20 is a cylindrical body, the second member 20 can be composed of a single layer or multiple layers. The second member 20 may be composed of a single layer in part in the longitudinal direction x or in the circumferential direction, and the other part may be composed of multiple layers. 【0112】 As shown in Figures 2 and 8, the catheter 1 has a linear member 60, and it is preferable that the linear member 60 is fixed to the proximal part of the second member 20. Having a linear member 60 fixed to the proximal part of the second member 20 makes it easier to pull the second member 20 proximal. By pulling the second member 20 proximal, the distal end 20d of the second member 20 is moved proximal, and the diameter of the bag-like body 30 can be expanded. 【0113】 The linear member 60 is a long wire. The wire constituting the linear member 60 may be a single wire or a stranded wire consisting of multiple single wires. 【0114】 The material constituting the linear member 60 is preferably a metal such as stainless steel, titanium, nickel-titanium alloy, cobalt-chromium alloy, or tungsten alloy, and more preferably stainless steel or a tungsten alloy. Because the material constituting the linear member 60 is metal, it can be made flexible and highly rigid, making it easier to draw the linear member 60 even in a curved body cavity. 【0115】 The length x in the longitudinal direction of the linear member 60 can be any length that allows it to be operated from the user's hand, or a length that allows it to be inserted into the lumen of the cylindrical member 81 described later, and an appropriate length can be selected as needed. 【0116】 Examples of cross-sectional shapes for the linear member 60 perpendicular to the longitudinal direction x include square, rectangular, trapezoidal, and circular shapes. Among these, a circular cross-sectional shape for the linear member 60 perpendicular to the longitudinal direction x is preferred. A circular cross-sectional shape for the linear member 60 makes it less likely for the linear member 60 to damage other objects when it comes into contact with them, such as when pulling the linear member 60. 【0117】 The outer diameter of the linear member 60 can be, for example, 0.2 mm or more and 1.0 mm or less. If the cross-sectional shape of the linear member 60 perpendicular to the longitudinal direction x is polygonal, the outer diameter of the linear member 60 refers to the diameter of the circumscribed circle of the cross-sectional shape of the linear member 60. 【0118】 Methods for fixing the linear member 60 to the proximal part of the second member 20 include, for example, welding by laser, brazing, crimping, bonding with adhesives such as acrylic, epoxy, or urethane, and fixing with heat shrink tubing. In particular, it is preferable that the linear member 60 is fixed to the proximal part of the second member 20 by bonding with an adhesive. By fixing the linear member 60 to the proximal part of the second member 20 by bonding with an adhesive, the bonding strength between the linear member 60 and the second member 20 can be easily increased. 【0119】 Although not shown in the figures, it is preferable that a gripping portion is provided on the proximal side of the linear member 60. Examples of materials that make up the gripping portion include synthetic resins such as polyethylene and polyolefin resins such as polypropylene. 【0120】 As shown in Figures 2 and 8, the first member 10 can be configured to have a first diameter reduction region 71 in the proximal part of the first member 10, in which the length in the radial direction y, when observed from a direction perpendicular to the longitudinal direction x, becomes shorter towards the proximal side. The presence of the first diameter reduction region 71 in the first member 10 increases the flexibility of the first member 10, making it easier for the first member 10 to bend to conform to the curved body cavity. 【0121】 The length of the first diameter reduction region 71 in the longitudinal direction x is preferably 50% or less of the length of the first member 10, more preferably 40% or less, and even more preferably 30% or less. By setting the upper limit of the ratio between the length of the first diameter reduction region 71 and the length of the first member 10 within the above range, the rigidity of the first member 10 can be maintained and the insertion of the catheter 1 can be improved. Furthermore, the length of the first diameter reduction region 71 in the longitudinal direction x is preferably 2% or more of the length of the first member 10, more preferably 4% or more, and even more preferably 6% or more. By setting the lower limit of the ratio between the length of the first diameter reduction region 71 and the length of the first member 10 within the above range, the flexibility of the first member 10 can be increased, making it easier to bend the first member 10. 【0122】 As shown in Figures 2 and 8, the linear member 60 is located proximal to the second member 20, and it is preferable that the linear member 60 is fixed to the second member 20 distal to the proximal end 71p of the first diameter reduction region 71. By fixing the linear member 60 distal to the proximal end 71p of the first diameter reduction region 71 to the second member 20, the linear member 60 can be easily pulled toward the user, and the movement of the second member 20 in the longitudinal direction x can be facilitated. 【0123】 As shown in Figures 2 and 8, the catheter 1 further includes a cylindrical member 81 whose maximum outer diameter is smaller than the maximum outer diameter of the first member 10, the distal portion of the cylindrical member 81 is fixed to the proximal portion of the first diameter reduction region 71, and the linear member 60 is preferably positioned in the lumen of the cylindrical member 81. Because the linear member 60 is positioned in the lumen of the cylindrical member 81, the linear member 60 is less likely to be exposed to the outside. Therefore, the linear member 60 is less likely to get tangled or caught on other objects, and the linear member 60 can be smoothly pulled towards the proximal end. 【0124】 The cylindrical member 81 is a cylindrical member having a lumen, and its maximum outer diameter is smaller than the maximum outer diameter of the first member 10. The minimum outer diameter of the cylindrical member 81 may be smaller than the minimum outer diameter of the first member 10. 【0125】 The material constituting the cylindrical member 81 can be the same synthetic resin or metal as the material constituting the first member 10. The material constituting the cylindrical member 81 may be different from the material constituting the first member 10, but it is preferable that it be the same material as the material constituting the first member 10. By using the same material as the material constituting the first member 10, it is possible to increase the strength of the fixation between the cylindrical member 81 and the first diameter reduction region 71. 【0126】 The length of the cylindrical member 81 in the longitudinal direction x can be selected appropriately according to the length of the linear member 60 placed in the lumen of the cylindrical member 81 in the longitudinal direction x. For example, the length of the cylindrical member 81 in the longitudinal direction x can be 100 mm or more and 2400 mm or less. 【0127】 The outer diameter of the cylindrical member 81 can be appropriately selected as needed, for example, it can be 0.6 mm or more and 3.0 mm or less. In particular, the outer diameter of the cylindrical member 81 is preferably 0.6 mm or more and 1.0 mm or less. By setting the outer diameter of the cylindrical member 81 within the above range, it is possible to prevent the outer diameter of the cylindrical member 81 from becoming too large and to prevent the outer diameter of the catheter 1 from becoming too large in accordance with the outer diameter of the cylindrical member 81. 【0128】 The inner diameter of the cylindrical member 81 can be, for example, 0.3 mm or more and 2.5 mm or less. In particular, the inner diameter of the cylindrical member 81 is preferably 0.5 mm or more and 0.9 mm or less. By setting the inner diameter of the cylindrical member 81 within the above range, it becomes easier to insert the linear member 60 into the lumen of the cylindrical member 81, and it is possible to keep the outer diameter of the cylindrical member 81 small. 【0129】 The cylindrical member 81 may have a lubricating coating on its outer surface. Fluorine-based resins such as PTFE, PFA, and ETFE can be used as the lubricating coating. The lubricating coating on the outer surface of the cylindrical member 81 increases its slipperiness, thereby improving the insertion of the catheter 1. 【0130】 Although not shown in the diagram, position markers may be provided on the tubular member 81 to confirm the length of catheter 1 inserted into the body cavity. Methods for providing position markers on the tubular member 81 include, for example, placing markers on the tubular member 81 or partially peeling off the coating applied to the outer surface of the tubular member 81. Multiple position markers can be present on the tubular member 81. Specifically, if the length x in the longitudinal direction of catheter 1 is 2400 mm, a configuration may be provided in which position markers are provided at positions 600 mm proximal to the distal end of catheter 1, 900 mm proximal to the distal end, and 1200 mm proximal to the distal end. 【0131】 Methods for fixing the distal portion of the cylindrical member 81 to the proximal portion of the first diameter reduction region 71 include, for example, welding by laser, brazing, riveting, and bonding with adhesives such as acrylic, epoxy, or urethane. In particular, it is preferable that the distal portion of the cylindrical member 81 is fixed to the proximal portion of the first diameter reduction region 71 by bonding with an adhesive. By fixing the distal portion of the cylindrical member 81 to the proximal portion of the first diameter reduction region 71 by bonding with an adhesive, it becomes possible to easily and firmly fix the cylindrical member 81 and the first diameter reduction region 71. 【0132】 As shown in Figures 2 and 8, it is preferable that the second member 20 has a second diameter reduction region 72 in the proximal part of the second member 20, in which the length in the radial direction y, when observed from a direction perpendicular to the longitudinal direction x, becomes shorter towards the proximal side. The presence of the second diameter reduction region 72 in the second member 20 increases the flexibility of the second member 20, making it easier to bend the second member 20 along a curved body cavity. 【0133】 The length of the second diameter reduction region 72 in the longitudinal direction x is preferably 50% or less of the length of the second member 20, more preferably 40% or less, and even more preferably 30% or less. By setting the upper limit of the ratio between the length of the second diameter reduction region 72 and the length of the second member 20 within the above range, the rigidity of the second member 20 can be maintained, and the insertion of the catheter 1 can be improved. Furthermore, the length of the second diameter reduction region 72 in the longitudinal direction x is preferably 2% or more of the length of the second member 20, more preferably 4% or more, and even more preferably 6% or more. By setting the lower limit of the ratio between the length of the second diameter reduction region 72 and the length of the second member 20 within the above range, the flexibility of the second member 20 can be increased, making the second member 20 more flexible. 【0134】 As shown in Figure 1, it is preferable that the catheter 1 further has a hub 110 at the proximal end of the first member 10 or at the tubular member 81. The hub 110 has a port inside that communicates with the lumen of the first member 10 or the tubular member 81, and is used when introducing a material or fluid into the lumen of the first member 10 or the tubular member 81. The hub 110 may be directly connected to the proximal end 10p of the first member 10 or the proximal end of the tubular member 81, or it may be indirectly connected to the proximal end 10p of the first member 10 or the proximal end of the tubular member 81 via another member. 【0135】 Figure 9 is a cross-sectional view parallel to the longitudinal direction x of a catheter 1 according to another embodiment of the present invention. As shown in Figure 9, the catheter can be configured to include a shaft 90 positioned within the lumen of the first member 10 in a manner movable relative to the first member 10, and an expansion member 100 provided at the distal end of the shaft 90 and expanding in the radial direction y. 【0136】 The shaft 90 can be configured to have a lumen extending in the longitudinal direction x. The lumen of the shaft 90 can be used as an insertion passage for a guidewire 120 or the like, as shown in Figure 9. 【0137】 The material constituting the shaft 90 may be the same synthetic resin or metal as the material constituting the first member 10. The material constituting the shaft 90 may be the same material as the material constituting the first member 10, or it may be a different material from the material constituting the first member 10. 【0138】 For example, a balloon or a stent can be used as the expansion member 100. 【0139】 The balloon is preferably made of resin. Examples of resins that make up the balloon include polyamide resins, polyester resins, polyurethane resins, polyolefin resins, vinyl chloride resins, silicone resins, and natural rubber. These may be used individually or in combination of two or more. Among these, polyamide resins, polyester resins, and polyurethane resins are preferably used as the resins that make up the balloon. Elastomer resins can be used from the viewpoint of thinning the balloon and improving its flexibility. 【0140】 A stent is an expandable structure composed of a mesh or other network structure, and includes multiple support columns. A stent can be formed from a pattern of interconnected structural elements that expand and contract in the circumferential and axial directions. Examples of stents include coils made of a single linear metal or polymer material, tubes made of metal or polymer material cut out with a laser, stents assembled by welding linear parts, and stents constructed by weaving multiple linear metals together. 【0141】 The stent is preferably made of a shape memory alloy or shape memory resin. The stent can be expanded smoothly if it is made of a shape memory alloy or shape memory resin. The stent may be made of, for example, stainless steel such as SUS304 or SUS316, platinum, nickel, cobalt, chromium, titanium, tungsten, aluminum, gold, silver, Ni-Ti alloy, Co-Cr alloy, etc. 【0142】 The stent may be a self-expanding stent or a balloon-expanding stent. 【0143】 The catheter 1 may be further configured to include a control mechanism that suppresses the movement of the shaft 90 in the longitudinal direction x within the lumen of the first member 10. Because the catheter 1 is equipped with a control mechanism, the movement of the shaft 90 in the longitudinal direction x within the lumen of the first member 10 is suppressed by the control mechanism, allowing the catheter 1 to be transported to the treatment area, thus facilitating the transport of the catheter 1 to the treatment area. 【0144】 Although not shown in the figures, one possible control mechanism is one in which a gripping member capable of gripping the shaft 90 is provided on the first member 10. By providing the gripping member on the first member 10, the shaft 90 can be gripped by the gripping member, and its movement in the longitudinal direction x within the lumen of the first member 10 can be temporarily suppressed. Then, by releasing the shaft 90 from the gripping member, the shaft 90 can be returned to a state in which it can move relative to the first member 10. Examples of gripping members include a rubber member with a slit for gripping the shaft 90, a clip made of synthetic resin, and so on. 【0145】 The expansion member 100 is preferably a balloon or stent with a coating layer formed on its outer surface. Having a coating layer on its outer surface increases the slipperiness of the outer surface of the expansion member 100, making it easier to release the expansion member 100 from the bag-like body 30. 【0146】 The coating layer can be formed by applying a coating agent to the outer surface of the balloon or stent. The coating layer may be formed on only a portion of the outer surface of the balloon or stent, or on the entire outer surface of the balloon or stent. The coating layer may contain a lubricating coating agent or a bioactive agent. 【0147】 Examples of lubricating coating agents include silicone-based coating agents such as silicone and polydimethylsiloxane; acrylic-based coating agents such as sodium (meth)acrylate, butyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, octyl (meth)acrylate, and 2,2,2-trifluoroethyl methacrylate; fluorine-based coatings such as polytetrafluoroethylene; and hydrophilic coating agents such as polyvinylpyrrolidone, hyaluronic acid, and polyethylene glycol. 【0148】 Examples of physiologically active agents include paclitaxel, docetaxel, sirolimus, temsirolimus, everolimus, zotarolimus, biolimus A9, cilostazol, cyclosporine, and NF-κB decoy oligos. These physiologically active agents may be used individually or in combination. Furthermore, the physiologically active substance may be used alone to coat the balloon or stent, or additives may be used in combination as appropriate. 【0149】 The coating layer preferably contains a bioactive agent. The inclusion of a bioactive agent in the coating layer of the balloon or stent enhances the efficiency of treatment when the balloon or stent is placed at the treatment site using catheter 1. 【0150】 Catheter 1 may further include a controller for catheter 1, devices used with catheter 1, a hub, etc. Although not shown in the figures, catheter 1 may be configured to have a locking mechanism at its proximal end for securing the controller, device, hub, etc. 【0151】 The length x in the longitudinal direction of catheter 1 can be selected as appropriate. For example, the length x in the longitudinal direction of catheter 1 can be between 200 mm and 2500 mm. [Explanation of symbols] 【0152】 1: Catheter 10: First component 10d: Distal end of the first member 10p: Proximal end of the first member 14: Insertion passage 15: Outer cylinder 16: Inner cylinder 20: Second component 20d: Distal end of the second member 21: Reduced section 21p: Proximal end of the reduced interval 30: Bag-like body 30d: Distal end of the sac-like structure 30p: Proximal end of the sac-like structure 40:X-ray opaque area 51: First shape memory member 52:Second shape memory section 60: Linear member 71: 1st diameter reduction area 71p: Proximal end of the first diameter reduction region 72:Second diameter reduction area 81: Cylindrical member 90: Shaft 100: Expansion member 110: Hub 120: Guidewire x: Longest direction y: radial direction C1: The smallest circle tangent to the surface of the second member in a cross section perpendicular to the longitudinal direction, centered on the central axis in the extending direction of the first member. P1: Point 1 P2: 2nd point A1: Region of the first member from the proximal end of the bag-like body to 10 cm proximal. A2: The region in the second member from the proximal end of the reduced section to 10 cm proximal.

Claims

[Claim 1] A first member having a distal end and a proximal end, and a lumen extending in the longitudinal direction, A bag-like body is provided at the distal end of the first member, is formed in an annular shape, and has an outer surface, an inner surface, and an internal space, The bag-like body has a second member which is positioned in the internal space and is movable in the longitudinal direction relative to the first member, The first member comprises an outer cylinder and an inner cylinder disposed within the cavity of the outer cylinder, and an insertion passage is formed in the space partitioned by the inner surface of the outer cylinder and the outer surface of the inner cylinder through which the second member is inserted. In a natural state where no external force is applied to the bag-like body, the shortest distance from the outer surface to the inner surface is smaller than the shortest distance from the outer surface to the inner surface of the first member. The second member, in a natural state where no external force is applied to the second member, has a reduced section in its distal portion in which the diameter of the smallest circle tangent to the surface of the second member in a cross section perpendicular to the longitudinal direction centered on the central axis in the extending direction of the first member is smaller than the outer diameter of the bag-like body. In the state in which the reduced portion of the second member is positioned inside the bag-like body, at least a portion of the surface of the bag-like body on the internal space side is in contact with the surface of the second member in the reduced portion. A catheter in which the minimum inner diameter of the bag-like body is smaller than the minimum inner diameter of the bag-like body when the distal end of the second member is located distal to the proximal end of the bag-like body and at least a portion of the surface of the bag-like body on the internal space side is in contact with the surface of the second member in the reduced section. [Claim 2] The catheter according to claim 1, wherein the internal space is in communication with the insertion passage. [Claim 3] The catheter according to claim 1 or 2, wherein the internal space is not in communication with the lumen of the first member. [Claim 4] The catheter according to any one of claims 1 to 3, wherein the length from the distal end to the proximal end of the bag-shaped body when the reduced section of the second member is positioned in the internal space of the bag-shaped body is longer than the length from the distal end to the proximal end of the bag-shaped body when the reduced section of the second member is not positioned in the internal space of the bag-shaped body. [Claim 5] The catheter according to claim 4, further comprising a movement suppression mechanism that suppresses longitudinal movement of the first member and the second member when the length from the distal end to the proximal end of the bag-shaped body is longer than the length from the distal end to the proximal end of the bag-shaped body when the reduced section of the second member is positioned in the internal space of the bag-shaped body. [Claim 6] The catheter according to any one of claims 1 to 5, wherein the rigidity of the second member in the direction perpendicular to the longitudinal direction in the reduced section is the same as or lower than the rigidity of the second member in the direction perpendicular to the longitudinal direction proximal to the reduced section. [Claim 7] The catheter according to any one of claims 1 to 6, wherein at least one of the regions in the first member from the proximal end of the bag-like body to 10 cm proximal and the region in the second member from the proximal end of the reduced section to 10 cm proximal is radiopaque. [Claim 8] The catheter according to claim 7, wherein the number of radiopaque portions arranged in the region of the first member from the proximal end to 10 cm proximal is greater than the number of radiopaque portions arranged in the region of the second member from the proximal end to 10 cm proximal is. [Claim 9] At least the bag-like body is provided with a first shape memory member, The elasticity of the first shape memory member is higher than that of the bag-shaped body. The catheter according to any one of claims 1 to 8, wherein, in a natural state in which no external force is applied to the first shape memory member, the diameter of the smallest circle in contact with the surface of the first shape memory member in a cross section perpendicular to the longitudinal direction centered on the central axis in the extending direction of the first member is greater than the minimum inner diameter of the bag-shaped body in a state in which the contracted section of the second member is in contact with the surface of the bag-shaped body on the internal space side. [Claim 10] At least the reduced portion of the second member has a second shape memory section, The catheter according to any one of claims 1 to 9, wherein the diameter of the smallest circle tangent to the surface of the second shape memory in a cross section perpendicular to the longitudinal direction centered on the central axis in the extending direction of the first member, in a natural state where no external force is applied to the second shape memory, is smaller than the diameter of the smallest circle tangent to the surface of the second member in a cross section perpendicular to the longitudinal direction centered on the central axis in the extending direction of the first member. [Claim 11] The catheter according to any one of claims 1 to 10, wherein the second member has a lumen extending in the longitudinal direction. [Claim 12] It has a linear member, The catheter according to any one of claims 1 to 11, wherein the linear member is fixed to the proximal portion of the second member. [Claim 13] The catheter according to any one of claims 1 to 12, wherein the first member has a first diameter reduction region in the proximal part of the first member, the radial length when observed from a direction perpendicular to the longitudinal direction is shortened towards the proximal side. [Claim 14] The linear member is located proximal to the second member, The catheter according to claim 13, wherein the linear member is fixed to the second member distal to the proximal end of the first diameter reduction region. [Claim 15] The present invention further comprises a cylindrical member whose maximum outer diameter is smaller than the maximum outer diameter of the first member, The distal portion of the cylindrical member is fixed to the proximal portion of the first diameter reduction region. The catheter according to claim 14, wherein the linear member is disposed in the lumen of the cylindrical member. [Claim 16] The catheter according to claim 11, wherein the second member has a second diameter reduction region in the proximal portion of the second member, the radial length when observed from a direction perpendicular to the longitudinal direction is shortened towards the proximal side. [Claim 17] A shaft is disposed within the lumen of the first member in a manner that allows it to move relative to the first member, The catheter according to any one of claims 1 to 16, further comprising an expansion member provided at the distal end of the shaft and expanding radially. [Claim 18] The catheter according to claim 17, further comprising a control mechanism for suppressing longitudinal movement of the shaft within the lumen of the first member. [Claim 19] The catheter according to claim 17 or 18, wherein the expansion member is a balloon or stent having a coating layer formed on its outer surface. [Claim 20] The catheter according to claim 19, wherein the coating layer contains a bioactive agent.

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