Stent delivery device

Abstract

To provide a stent carrying device capable of more surely indwelling a stent in a desired part.SOLUTION: The stent transfer device 100 includes the elongated inner sheath 20 to which the stent 200 is attached in an externally mounted state, the inner sheath 20 includes the sheath main portion 41 and the individual sheath portion 43 in which the first sheath 45 and the second sheath 47 are separated from each other, and the stent 200 is configured such that the first sheath 45 of the individual sheath portion 43 is inserted through the first branch tube 220. The inner sheath 20 is attached in a state in which the second sheath 47 of the individual sheath portion 43 is inserted through the second branch tube 230, the first radiopaque marker 51 is provided in the first sheath 45 of the individual sheath portion 43 at a position corresponding to the stent branch portion 211, and the second radiopaque marker 52 is provided in the second sheath 47 of the individual sheath portion 43 at a position corresponding to the stent branch portion 211.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a stent delivery device. [Background technology]

[0002] An example of a stent delivery device used to place a stent in a body cavity is described in Patent Document 1. The stent delivery device of Patent Document 1 (referred to as a stent placement system in the document) has a long inner sheath having a stent mounting section (referred to as a holding section in the document) to which the stent is attached in an exterior state when the stent is delivered, and the inner sheath is composed of a single tubular body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7446280 Summary of the Invention [Problem to be solved by the invention]

[0004] According to the investigations of the present inventors, the stent delivery device of Patent Document 1 still has room for improvement in terms of the structure for more reliably placing the stent at the desired site.

[0005] The present invention has been made in view of the above problems, and aims to provide a stent delivery device that can more reliably place a stent at a desired site. [Means for solving the problem]

[0006] According to the present invention, there is provided a stent delivery device for delivering a stent into a body, the stent having a main vessel and a first branch vessel and a second branch vessel each branching from a stent bifurcation portion which is a distal end of the main vessel, the stent delivery device comprising: a long inner sheath to which the stent is attached in an exterior state; the inner sheath has a sheath main portion in which a first sheath and a second sheath are bundled together, and an individual sheath portion in which the first sheath and the second sheath are separated and which is located distal to a sheath branch portion that is a distal end of the sheath main portion, the stent is attached to the inner sheath in a state in which the first sheath of the individual sheath portion is inserted into the first branch pipe and the second sheath of the individual sheath portion is inserted into the second branch pipe, a first radiopaque marker is provided in the first sheath of the individual sheath portion at a position corresponding to the stent bifurcation portion; A stent delivery device is provided in which a second radiopaque marker is provided on the second sheath of the individual sheath portion at a position corresponding to the stent bifurcation portion. [Effects of the Invention]

[0007] According to the present invention, the stent can be placed more reliably at the desired site. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic overall view of a stent delivery device according to an embodiment. [Figure 2] FIG. 2(a) is a side view showing the distal end of the stent delivery device according to the embodiment, and FIG. 2(b) is a partially enlarged view of part A shown in FIG. 2(a). [Figure 3] FIG. 3(a) is a side view schematically showing a state in which a stent is attached to an inner sheath in the embodiment, and FIG. 3(b) is a side view of the inner sheath in the embodiment. [Figure 4] FIG. 3(b) is a cross-sectional view taken along the line AA shown in FIG. [Figure 5] FIG. 2 is a side view showing a first radiopaque marker and its surrounding structure in an embodiment. [Figure 6]Figure 6(a) is a cross-sectional view showing the first radiopaque marker and its surrounding structure in an embodiment, Figure 6(b) is a partially enlarged view of part A shown in Figure 6(a), and Figure 6(c) is a partially enlarged view of part B shown in Figure 6(b). [Figure 7] FIG. 1 is a schematic side view of a stent according to an embodiment. [Figure 8] Figures 8(a) and 8(b) are diagrams for explaining the operation of the stent delivery device of the embodiment, where Figure 8(a) shows the state in which the guide wire is inserted into the bile duct, and Figure 8(b) shows the state in which the distal end of the stent delivery device is inserted up to the bifurcation of the common hepatic duct. [Figure 9] Figures 9(a) and 9(b) are diagrams for explaining the operation of the stent delivery device according to the embodiment. Of these, Figure 9(a) shows a state in which the individual sheath portion of the inner sheath is exposed from the outer sheath, and Figure 9(b) shows a state in which the inner sheath has been further advanced from the state shown in Figure 9(a). [Figure 10] Figures 10(a) to 10(c) are diagrams for explaining the operation of the stent delivery device of the embodiment, and schematically show the first radiopaque marker, the second radiopaque marker, and their surrounding structures under X-ray (radiation) observation. [Figure 11] 10 is a side view showing the first radiopaque marker and its surrounding structure in Modification 1. FIG. [Figure 12] 12(a) is a partial enlarged view of part A shown in FIG. 11, and FIG. 12(b) is a partial enlarged view of part B shown in FIG. [Figure 13] FIG. 10 is a side view showing the first radiopaque marker and its surrounding structure in Modification 2. [Figure 14] 14(a) is a partial enlarged view of part A shown in FIG. 13, and FIG. 14(b) is a partial enlarged view of part B shown in FIG. [Figure 15] Figures 15(a) to 15(c) are diagrams for explaining the operation of a stent delivery device relating to variant example 2, and schematically show the first radiopaque marker, the second radiopaque marker, and their surrounding structures under X-ray (radiation) observation. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to Figures 1 to 10(c). In all the drawings, the same components are denoted by the same reference numerals, and the description thereof will be omitted where appropriate. The various components of the stent delivery device 100 of the present invention do not necessarily have to be independent entities. It is acceptable for multiple components to be formed as a single member, for one component to be formed from multiple members, for one component to be a part of another component, or for part of one component to overlap with part of another component. In the following description, the tip end side of the stent delivery device 100 is also referred to as the distal side, and its base end side as the proximal side. The distal end refers to a certain range including the distal end (the most distal end) and its periphery, and the proximal end refers to a certain range including the proximal end (the most proximal end) and its periphery. The directions toward the distal and proximal sides are also referred to as the tip-to-base direction or axial direction.

[0010] The stent delivery device 100 of this embodiment delivers a stent 200 (see Figure 7) into the body, which has a main vessel 210 and a first branch vessel 220 and a second branch vessel 230 each branching off from a stent bifurcation portion 211, which is the distal end of the main vessel 210. As shown in Figures 1 to 3(b), the stent delivery device 100 includes an elongated inner sheath 20 to which a stent 200 is attached in an exterior state. The inner sheath 20 has a sheath main portion 41 in which a first sheath 45 and a second sheath 47 are bundled together, and an individual sheath portion 43 located distal to a sheath branch portion 42 that is the distal end of the sheath main portion 41, and in which the first sheath 45 and the second sheath 47 are separated. The stent 200 is attached to the inner sheath 20 with the first sheath 45 of the individual sheath portion 43 inserted into the first branch pipe 220 and the second sheath 47 of the individual sheath portion 43 inserted into the second branch pipe 230. A first radiopaque marker 51 is provided in the first sheath 45 of the individual sheath portion 43 at a position corresponding to the stent branch portion 211, and a second radiopaque marker 52 is provided in the second sheath 47 of the individual sheath portion 43 at a position corresponding to the stent branch portion 211. Here, "a position corresponding to the stent branch portion 211" means that when the stent 200 is attached to the inner sheath 20, the formation area of ​​the first radiopaque marker 51 (or the second radiopaque marker 52) straddles the stent branch portion 211 in the tip-to-base direction. Furthermore, as will be described later, when the first radiopaque marker 51 is formed by a plurality of first tubular portions 51a, the "formation region of the first radiopaque marker 51" refers to the region from the distal end of the most distally arranged first tubular portion 51a (hereinafter referred to as the distal first tubular portion 51aa) to the proximal end of the most proximal arranged first tubular portion 51a (hereinafter referred to as the proximal first tubular portion 51ab) in the tip-to-proximal direction. Similarly, when the second radiopaque marker 52 is formed by a plurality of second tubular portions, the "formation region of the second radiopaque marker 52" refers to the region from the distal end of the most distally arranged second tubular portion 52a (hereinafter referred to as the distal second tubular portion 52aa) to the proximal end of the most proximal arranged second tubular portion (hereinafter referred to as the proximal second tubular portion 52ab) in the tip-to-proximal direction. Furthermore, "bundled" here means that the first sheath 45 and the second sheath 47 are constrained so as not to be separated from each other, and "separated" means that the first sheath 45 and the second sheath 47 can be bent in directions moving away from and toward each other.

[0011] The stent delivery device 100 is used to place the stent 200 at a desired site in a body cavity. When placing the stent 200, as described below, the inner sheath 20 to which the stent 200 is attached is fed to a desired site in the body cavity while sliding from the proximal side to the distal side. More specifically, the first sheath 45 and the second sheath 47, and thus the first branch duct 220 and the second branch duct 230, are inserted into different sites (for example, the left hepatic duct 512 and the right hepatic duct 513 (see FIG. 8(b) and the like)). In this state, the stent 200 is switched from the contracted state to the expanded state, thereby placing the stent 200. After the stent 200 is placed, the inner sheath 20 is pulled proximally to withdraw the inner sheath 20 from the stent 200.

[0012] With this configuration, under X-ray (radiation) observation, the user can easily grasp the positions of the first sheath 45 and the second sheath 47, and further the positions of the first branch tube 220 and the second branch tube 230 of the stent 200, using the positions of the first radiopaque marker 51 and the second radiopaque marker 52 as indicators. This allows the stent 200 to be placed at a desired site more reliably.

[0013] As described above, the stent 200 has a main vessel 210 and a first branch vessel 220 and a second branch vessel 230 each branching from a stent bifurcation portion 211 which is the distal end of the main vessel 210 . As shown in FIG. 7, the main pipe 210, the first branch pipe 220 and the second branch pipe 230 are each formed, for example, in a cylindrical shape with a mesh structure. The lumen region of the main vessel 210 communicates with the lumen region of the first branch vessel 220 and the lumen region of the second branch vessel 230 at the distal end (stent bifurcation 211) of the main vessel 210, respectively. For example, the axial direction of the first branch vessel 220 and the axial direction of the second branch vessel 230 are both inclined relative to the axial direction of the main vessel 210, and the overall shape of the stent 200 is Y-shaped. In the present invention, the stent 200 may be, for example, a stent graft having a tubular graft formed from a graft material. Furthermore, in the present invention, the shape of the stent 200 is not limited to this example, and for example, the stent 200 may be composed of a single mesh-structured cylinder, the entirety of which may be formed in an approximately linear (I-shaped) shape.

[0014] As shown in Figure 3(a), the stent 200 is attached to the stent mounting section 21 in a reduced-diameter state while being restrained by a string member 240. One end (not shown) of the string member 240 is led out from the proximal side to the outside of the stent delivery device 100. Similarly, one end (not shown) of the wire member 250 is led out from the proximal side to the outside of the stent delivery device 100. In addition, a wire member 250 is fixed to the string member 240, and the string member 240 can be released from the stent 200 by pulling the wire member 250 out to the proximal side. This releases the string member 240 from restraint on the stent 200, and the stent 200 changes from the reduced-diameter state to the deployed state. More specifically, in this embodiment, the string member 240 and wire member 250 that restrain the first branch pipe 220 of the stent 200 and the string member 240 and wire member 250 that restrain the second branch pipe 230 are separate members. Therefore, the first branch pipe 220 and the second branch pipe 230 can be changed from the contracted state to the expanded state at different times. Note that Figure 3(a) schematically illustrates the stent 200, the string member 240, and the wire member 250. Furthermore, in Figure 2(a), the placement section of the stent 200 is illustrated by a two-dot chain line.

[0015] 1, a stent delivery device 100 includes, in addition to an inner sheath 20, an outer sheath 10 fitted over the inner sheath 20 so as to be slidable in the axial direction, an operation unit 90 to which the proximal end of the outer sheath 10 is fixed, a shaft 92 extending from the operation unit 90 toward the proximal end, and a shaft handle 91 to which the proximal end of the shaft 92 is fixed. Note that in Figures 2(a) and 2(b), the outer sheath 10 is selectively illustrated as a cross section taken along the axial center of the outer sheath 10. The stent 200 is housed in a reduced-diameter state between the inner circumferential surface of the outer sheath 10 and the outer circumferential surface of the inner sheath 20. Then, with the outer sheath 10 and the inner sheath 20 inserted into a desired site in a body cavity along a guidewire 300 (see FIG. 8(a) and the like), the operation section 90 is retracted together with the outer sheath 10 toward the shaft handle 91, and the stent mounting section 21 of the inner sheath 20 is exposed from the outer sheath 10. Then, by withdrawing the wire member 250 proximally and releasing the string member 240 restraining the stent 200, the stent 200 can be transformed from the reduced-diameter state to the expanded state and placed at the desired site. The reduced-diameter state of the stent 200 refers to a state in which the stent 200 is compressed in the radial direction to an extent that the stent 200 can be present within the outer sheath 10. The expanded-diameter state of the stent 200 refers to a state in which the diameter is at least larger than the reduced-diameter state, such as the natural state of the stent 200.

[0016] The outer sheath 10 is a long, hollow tubular member. As shown in Figures 2(a) and 2(b), the inner sheath 20 is inserted into the lumen of the outer sheath 10, and the outer sheath 10 is slidable relative to the inner sheath 20 in the axial direction. In this embodiment, the inner and outer diameters of the outer sheath 10 are constant regardless of the position in the axial direction, and therefore the wall thickness of the outer sheath 10 is constant regardless of the position in the axial direction. However, the outer and inner diameters of the outer sheath 10 may differ depending on the position in the axial direction. The outer sheath 10 has, for example, a two-layer structure (not shown) including an inner layer and an outer layer disposed around the inner layer, and is configured by laminating the inner layer and the outer layer in that order from the axial center side of the outer sheath 10. A hydrophilic layer (not shown) may be formed on the surface of the outer layer. The material of the hydrophilic layer is not particularly limited, but examples thereof include hydrophilic resin materials such as maleic anhydride polymers such as polyvinyl alcohol (PVA) and copolymers thereof, and polyvinylpyrrolidone. This can reduce the sliding resistance when the outer sheath 10 is inserted into a body cavity of a living body. The inner layer is made of, for example, a fluorine-based thermoplastic polymer resin. The fluorine-based thermoplastic polymer material is not particularly limited, but may be polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), perfluoroalkoxy fluororesin (PFA), or the like. By making the inner layer out of such a fluorine-based polymer material, sliding resistance when the inner sheath 20 slides in the lumen of the outer sheath 10 is reduced. The outer layer may be made of, for example, a thermoplastic polymer material, such as polyimide (PI), polyamideimide (PAI), polyethylene terephthalate (PET), polyethylene (PE), polyamide (PA), polyamide elastomer (PAE), nylon elastomer such as polyether block amide (PEBA), polyurethane (PU), ethylene-vinyl acetate resin (EVA), polyvinyl chloride (PVC), or polypropylene (PP).

[0017] The inner diameter of the outer sheath 10 is set to a dimension larger than the outer diameter (maximum diameter) of the inner sheath 20. Therefore, the inner sheath 20 can be slidably inserted into the inner cavity of the outer sheath 10. More specifically, the inner diameter of the outer sheath 10 is not particularly limited, but is preferably 1 mm or more and 7 mm or less. The outer diameter of the outer sheath 10 is not particularly limited, but is preferably 1.5 mm or more and 8 mm or less. Furthermore, the total length of the outer sheath 10 is not particularly limited, but is preferably 500 mm or more and 2500 mm or less.

[0018] Furthermore, the outer sheath 10 includes a reinforcing layer (not shown) formed in a mesh shape by braiding metal wires, for example. The reinforcing layer is disposed, for example, from the distal end to the proximal end of the outer sheath 10. The outer sheath 10 is reinforced throughout by the reinforcing layer. The reinforcing layer may be formed of, for example, a metal wire wound in a coil shape, and may be disposed on, for example, a portion of the outer sheath 10 in the axial direction.

[0019] In this embodiment, a cylindrical radiopaque marker 55, for example, is embedded near the distal end of the outer sheath 10. The radiopaque marker 55 is made of an X-ray opaque material, such as platinum, tungsten, etc. By using the position of the radiopaque marker 55 as an index, the position of the distal end of the outer sheath 10 within the body cavity can be accurately recognized under X-ray (radiation) observation.

[0020] As described above, the inner sheath 20 has a first sheath 45 inserted into the main vessel 210 and the first branch vessel 220 of the stent 200, and a second sheath 47 inserted into the main vessel 210 and the second branch vessel 230. The inner sheath 20 also has a sheath main portion 41 in which a first sheath 45 and a second sheath 47 are bundled together, and an individual sheath portion 43 that is located distal to a sheath branch portion 42 that is the distal end of the sheath main portion 41 and in which the first sheath 45 and the second sheath 47 are separated. More specifically, in the present embodiment, the inner sheath 20 further includes a third sheath 49 through which both the first sheath 45 and the second sheath 47 are inserted. The third sheath 49 is formed in a long tubular shape. A partial section of the first sheath 45 and a partial section of the second sheath 47 are inserted into the inner cavity of the third sheath 49 and bundled together. The distal end of the third sheath 49 terminates proximally relative to the distal ends of the first sheath 45 and the second sheath 47. In other words, the distal end portions of the first sheath 45 and the second sheath 47 each branch and extend distally from the distal end of the third sheath 49. In the inner sheath 20, the distal end of the third sheath 49 is the sheath branching section 42, the portion proximal to the distal end constitutes the sheath main section 41, and the portion distal to the distal end constitutes the individual sheath section 43. In this embodiment, the portion of the inner sheath 20 distal to the distal end of the third sheath 49 (individual sheath portion 43) constitutes a stent mounting portion 21 to which the stent 200 is attached in an exterior state when the stent 200 is delivered, and the entire stent 200 is extrapolated onto this stent mounting portion 21. As shown in FIG. 3( a), the stent 200 is attached to the inner sheath 20 in a state in which the first sheath 45 and the second sheath 47 of the individual sheath portion 43 are both inserted into the main tube 210, the first sheath 45 of the individual sheath portion 43 is inserted into the first branch tube 220, and the second sheath 47 of the individual sheath portion 43 is inserted into the second branch tube 230. 2(a) and 2(b), when inserted into the lumen of the outer sheath 10, the first sheath 45 and the second sheath 47 of the individual sheath portion 43 extend approximately parallel to each other along the axial direction of the outer sheath 10. Similarly, the first branch tube 220, through which the first sheath 45 of the individual sheath portion 43 is inserted, and the second branch tube 230, through which the second sheath 47 of the individual sheath portion 43 is inserted, are also restrained by the outer sheath 10 in a state where they extend approximately parallel to each other along the axial direction. As shown in FIG. 3(a), when the individual sheath portion 43 is exposed from the outer sheath 10, the first sheath 45 and the second sheath 47 of the individual sheath portion 43 are bendable in directions moving away from and toward each other.

[0021] The inner diameter and the outer diameter of the third sheath 49 are constant regardless of the position in the axial direction. 4, for example, in addition to the first sheath 45 and the second sheath 47, a fourth sheath 46a and a fifth sheath 46b are also inserted into the lumen of the third sheath 49. A wire member 250 that maintains the ligated state of the string member 240 is inserted into the fourth sheath 46a, and the string member 240 that restrains the stent 200 is inserted into the fifth sheath 46b. One end (not shown) of the wire member 250 is led out of the stent delivery device 100 via the fourth sheath 46a. The other end of the wire member 250 is led out from the distal end of the fourth sheath 46a toward the stent 200. One end (not shown) of the string member 240 is led out of the stent delivery device 100 via the fifth sheath 46b. The other end of the string member 240 is led out from the distal end of the fifth sheath 46b toward the stent 200. Each of the fourth sheath 46a and the fifth sheath 46b terminates in the axial direction at a position equivalent to or more proximal to the distal end of the third sheath 49. In other words, of the first sheath 45, the second sheath 47, the fourth sheath 46a, and the fifth sheath 46b, the first sheath 45 and the second sheath 47 constitute the individual sheath portion 43.

[0022] Here, a portion of the stent mounting section 21 is formed, for example, as a large diameter section 22 formed with a larger diameter than the other sections. More specifically, in the present embodiment, each of the first sheath 45 and the second sheath 47 has a large diameter section 22. This allows the first branch tube 220 to be securely engaged with the large diameter portion 22 of the first sheath 45, and the second branch tube 230 to be securely engaged with the large diameter portion 22 of the second sheath 47. This prevents the first branch tube 220 from being displaced in the axial direction relative to the first sheath 45 when the first sheath 45 is retracted or advanced, and prevents the second branch tube 230 from being displaced in the axial direction relative to the second sheath 47 when the second sheath 47 is retracted or advanced. This allows the first branch tube 220 and the second branch tube 230 to be more reliably placed at the desired site. The method for forming the large diameter portion 22 is not particularly limited, and the large diameter portion 22 may be formed by exteriorly covering the tubular body (for example, the inner sheath body 31 described below) that constitutes the first sheath 45 and the second sheath 47 with a tube made of a separate member, or may be integrally molded with the tubular body.

[0023] In the present embodiment, each of the first sheath 45 and the second sheath 47 is formed by an inner sheath body 31 . The inner sheath body 31 is formed, for example, in the shape of a long tube. The inner diameter and the outer diameter of the inner sheath body 31 are constant regardless of the position in the axial direction. The inner sheath body 31 of the first sheath 45 and the inner sheath body 31 of the second sheath 47 are set to have the same length dimension, and are also set to have the same inner diameter and outer diameter.

[0024] Furthermore, a distal tip 38 (see FIGS. 1 and 2(b), etc.) is provided at the distal end of each of the inner sheath body 31 of the first sheath 45 and the inner sheath body 31 of the second sheath 47. The distal tip 38 is formed, for example, in a conical shape whose diameter gradually decreases toward the distal side. The proximal end of the distal tip 38 is connected to the distal end of the inner sheath body 31, and the inner lumen of the distal tip 38 and the inner lumen of the inner sheath body 31 communicate with each other. When inserting the stent delivery device 100 into a body cavity, the guidewire 300 (see FIG. 8(a) and other figures) that has been inserted into the body cavity in advance is inserted into the lumen of the inner sheath body 31 from the distal opening of the tip 38. This allows the outer sheath 10 and the inner sheath 20 to be inserted into the body cavity along the guidewire 300.

[0025] As described above, a first radiopaque marker 51 is provided on the first sheath 45 of the individual sheath portion 43 at a position corresponding to the stent branch portion 211, and a second radiopaque marker 52 is provided on the second sheath 47 of the individual sheath portion 43 at a position corresponding to the stent branch portion 211. In this embodiment, of the first sheath 45 and the second sheath 47, the distal tip 38 of the first sheath 45 is provided with a third radiopaque marker 53. This allows the user to easily distinguish between the first sheath 45 and the second sheath 47, and ultimately the first branch tube 220 and the second branch tube 230 of the stent 200, under X-ray (radiation) observation, using the position of the third radiopaque marker 53 as an indicator. Furthermore, a fourth radiopaque marker 54 is provided at the distal end of the third sheath 49. This allows the user to easily determine the position of the sheath branching portion 42 by using the position of the third radiopaque marker 53 as an index. In Figures 2(a), 2(b), 3(a), 3(b), and 10(a) to 10(c), the areas where the first radiopaque marker 51 to the fourth radiopaque marker 54 are formed are shaded with dots.

[0026] The first radiopaque marker 51 to the fourth radiopaque marker 54 are made of an X-ray opaque material, such as platinum or tungsten. However, the present invention is not limited to this example, and the first radiopaque marker 51 to the fourth radiopaque marker 54 may be formed, for example, by applying ink to the outer peripheral surface of the inner sheath body 31. The outer sheath 10 is made of, for example, a transparent resin material (transparent to visible light). Therefore, the user can visually recognize the first to fourth radiopaque markers 51 to 54 through the outer sheath 10.

[0027] 5 and 6(a), etc., the first radiopaque marker 51 is formed in a tubular shape, the portion of the first sheath 45 where the first radiopaque marker 51 is provided is a first constricted portion 32 formed with a smaller diameter than the remaining portions, and the first radiopaque marker 51 is fitted onto the first constricted portion 32. The second condition is that the second radiopaque marker 52 is formed in a tubular shape, the portion of the second sheath 47 where the second radiopaque marker 52 is provided is a second constricted portion (not shown) formed with a smaller diameter than the remaining portions, and the second radiopaque marker 52 is fitted onto the second constricted portion. At least one of the first and second conditions is satisfied. Note that FIGS. 6(a) and 6(b) are cross-sectional views taken along the axis of the inner sheath body 31. This configuration can further reduce the step formed at the boundary between the first radiopaque marker 51 or the second radiopaque marker 52 and other portions in at least one of the first sheath 45 and the second sheath 47. This can therefore prevent at least one of the first radiopaque marker 51 and the second radiopaque marker 52 from interfering with the inner circumferential surface of the outer sheath 10 or the stent 200, for example.

[0028] In this embodiment, the stent delivery device 100 satisfies both the first and second conditions. Therefore, in the first sheath 45, the step formed at the boundary between the first radiopaque marker 51 and other parts can be made smaller, and in the second sheath 47, the step formed at the boundary between the second radiopaque marker 52 and other parts can be made smaller.

[0029] More specifically, if the third condition is that the first condition is satisfied and the first radiopaque marker 51 is composed of a plurality of first tubular portions 51a (see Figures 5 and 6(a)) connected in the distal-proximal direction, and the fourth condition is that the second condition is satisfied and the second radiopaque marker 52 is composed of a plurality of second tubular portions 52a connected in the distal-proximal direction, then at least one of the third and fourth conditions is satisfied. This allows the first sheath 45 (or the second sheath 47) to be easily bent at the boundary of the first tubular portion 51a (at least the second tubular portion 52a) even in the region where at least the first radiopaque marker 51 (or the second radiopaque marker 52) is formed. That is, it is possible to ensure good bendability of the first sheath 45 (or the second sheath 47).

[0030] In the present embodiment, the stent delivery device 100 satisfies both the third and fourth conditions. This allows the first sheath 45 to be easily bent at the boundaries of the first tubular portions 51a even in the formation region of the first radiopaque marker 51, and also allows the first sheath 45 to be easily bent at the boundaries between multiple first tubular portions 51a even in the formation region of the first radiopaque marker 51.

[0031] More specifically, in the case of this embodiment, the first radiopaque marker 51 and the second radiopaque marker 52 (the plurality of first tubular portions 51a and the plurality of second tubular portions 52a) are fixed by crimping to the corresponding inner sheath body 31. As a result, the first radiopaque marker 51 and the second radiopaque marker 52 are embedded in the inner sheath body 31, and a first constricted portion 32 and a second constricted portion are formed in the formation region of the first radiopaque marker 51 and the second radiopaque marker 52. More specifically, in the first sheath 45, a plurality of positions in the distal-proximal direction form the first constricted portions 32, and one first tubular portion 51a is fitted onto each first constricted portion 32. Similarly, in the second sheath 47, a plurality of positions in the distal-proximal direction form the second constricted portions, and one second tubular portion 52a is fitted onto each second constricted portion.

[0032] In addition, adhesive may be applied between the inner surface of the first radiopaque marker 51 (plurality of first tubular portions 51a) and the first constricted portion 32, and between the inner surface of the second radiopaque marker 52 (plurality of second tubular portions 52a) and the second constricted portion, for example.

[0033] As shown in Figures 5 and 6(a), in this embodiment, the multiple first tubular portions 51a are arranged side by side in the proximal-proximal direction. A small gap is formed between adjacent first tubular portions 51a in the proximal-proximal direction. The length of the gap between adjacent first tubular portions 51a in the proximal-proximal direction is preferably, for example, equal to or less than the outer diameter of the first tubular portions 51a. More preferably, the length of the gap between adjacent first tubular portions 51a in the proximal-proximal direction is, for example, equal to or less than 1 / 3 of the outer diameter of the first tubular portions 51a. It should be noted that the present invention is not limited to this example, and the first tubular portions 51a may be arranged in close contact with each other with no gaps in the tip-to-proximal direction.

[0034] In addition, in this embodiment, the boundary between the proximal first tubular portion 51ab, which is the first tubular portion located most proximally among the multiple first tubular portions 51a, and another first tubular portion 51a (in this embodiment, the distal first tubular portion 51aa) adjacent to the proximal first tubular portion 51ab on the distal side is positioned at a position in the first sheath 45 corresponding to the stent branch portion 211. Similarly, the boundary between the proximal second tubular portion 52ab, which is the second tubular portion 52a located most proximally among the multiple second tubular portions 52a, and another second tubular portion 52a adjacent to the proximal second tubular portion 52ab on the distal side (in this embodiment, the distal second tubular portion 52aa) is positioned at a position in the second sheath 47 corresponding to the stent branch portion 211. Here, "the boundary between the proximal first tubular portion 51ab and another first tubular portion 51a (distal first tubular portion 51aa) adjacent to the distal side of the proximal first tubular portion 51ab is positioned at a position corresponding to the stent branch portion 211 in the first sheath 45" means that when the stent 200 is attached to the inner sheath 20, the shortest distance between the boundary and the stent branch portion 211 in the tip-to-base direction is three times or less the outer diameter of the first radiopaque marker 51. Similarly, "the boundary between the proximal second tubular portion 52ab and another second tubular portion 52a (distal second tubular portion 52aa) adjacent to the distal side of the proximal second tubular portion 52ab is positioned at a position corresponding to the stent branch portion 211 in the second sheath 47" means that when the stent 200 is attached to the inner sheath 20, the shortest distance between the boundary portion and the stent branch portion 211 in the tip-to-base direction is three times or less the outer diameter of the second radiopaque marker 52. According to this configuration, as will be described later, when the stent bifurcation 211 reaches the bifurcation 511a of the bile duct 510, the distal ends of the first radiopaque marker 51 and the second radiopaque marker 52 are inserted into the left hepatic duct 512 and the right hepatic duct 513, respectively, and gradually separate (separate) from each other distally, while the proximal ends (proximal first tubular portion 51ab and proximal second tubular portion 52ab) of the first radiopaque marker 51 and the second radiopaque marker 52 extend parallel to each other in the common hepatic duct 511. Therefore, under X-ray (radiation) observation, the aggregate of the first radiopaque marker 51 and the second radiopaque marker 52 can form a bifurcated Y-shape from the common hepatic duct 511 toward the left hepatic duct 512 and the right hepatic duct 513.

[0035] More specifically, in this embodiment, the first radiopaque marker 51 is composed of two first tubular portions 51a (a distal first tubular portion 51aa and a proximal first tubular portion 51ab). In the tip-to-proximal direction, a gap 51c is formed at the boundary between the distal first tubular portion 51aa and the proximal first tubular portion 51ab. In the first sheath 45, the boundary (gap 51c) between the distal first tubular portion 51aa and the proximal first tubular portion 51ab is located at a position corresponding to the stent bifurcation portion 211. That is, of the first radiopaque marker 51, the distal first tubular portion 51aa is located mainly in the first branch vessel 220, while the proximal first tubular portion 51ab is located mainly in the main vessel 210. Similarly, the second radiopaque marker 52 is composed of two second tubular portions (a distal second tubular portion 52aa and a proximal second tubular portion 52ab). In the tip-to-base direction, a gap (not shown) is formed at the boundary between the distal second tubular portion 52aa and the proximal second tubular portion 52ab. In the second sheath 47, the boundary (gap) between the distal second tubular portion 52aa and the proximal second tubular portion 52ab is located at a position corresponding to the stent bifurcation portion 211. That is, of the second radiopaque marker 52, the distal second tubular portion 52aa is located mainly in the second branch vessel 230, while the proximal second tubular portion 52ab is located mainly in the main vessel 210. According to this configuration, as will be described later, when the stent bifurcation 211 reaches the bifurcation 511a of the bile duct 510, the distal first tubular portion 51aa and the distal second tubular portion 52aa are inserted into the left hepatic duct 512 and the right hepatic duct 513, respectively, and gradually move away from each other distally, while the proximal first tubular portion 51ab and the proximal second tubular portion 52ab extend parallel to each other in the common hepatic duct 511. Therefore, under X-ray (radiation) observation, the aggregate of the first radiopaque marker 51 and the second radiopaque marker 52 can form a bifurcated Y-shape extending from the common hepatic duct 511 toward the left hepatic duct 512 and the right hepatic duct 513.

[0036] In the present invention, the number of first tubular portions 51a constituting the first radiopaque marker 51 (or the number of second tubular portions 52a constituting the second radiopaque marker 52) is not particularly limited, and can be set appropriately depending on the dimensions and use of the inner sheath 20, etc.

[0037] The first radiopaque marker 51 is formed in a tubular shape with a larger diameter than the first sheath 45. The first sheath 45 has a first distal adjacent portion 26, which is a portion of the first sheath 45 adjacent to the distal side of the first radiopaque marker 51, and a first proximal adjacent portion 27, which is a portion of the first sheath 45 adjacent to the proximal side of the first radiopaque marker 51. Similarly, the second radiopaque marker 52 is formed in a tubular shape with a larger diameter than the second sheath 47. The second sheath 47 has a second distal adjacent portion (not shown) which is a portion of the second sheath 47 adjacent to the distal side of the second radiopaque marker 52, and a first proximal adjacent portion (not shown) which is a portion of the second sheath 47 adjacent to the proximal side of the second radiopaque marker 52. More specifically, the first condition is satisfied, and the outer diameter of the proximal end of the first radiopaque marker 51 is larger than the outer diameter of the first proximal adjacent portion 27, which is the portion of the first sheath 45 adjacent to the proximal side of the formation area of ​​the first radiopaque marker 51, and the step portion 28 (see Figure 6(b)) between the proximal end of the first radiopaque marker 51 and the first proximal adjacent portion 27 is filled with a first resin 62a. Then, the fifth condition is that the outer surface of the first resin 62a, for example, tapers in diameter toward the proximal side, and the sixth condition is that the second condition is satisfied and the outer diameter of the proximal end of the second radiopaque marker 52 is larger than the outer diameter of the second proximal adjacent portion, which is the portion of the second sheath 47 adjacent to the proximal side of the formation area of ​​the second radiopaque marker 52, the step portion (not shown) between the proximal end of the second radiopaque marker 52 and the second proximal adjacent portion is filled with a second resin (not shown), and the outer surface of the second resin tapers in diameter toward the proximal side, then at least one of the fifth and sixth conditions is satisfied. 6(c) shows a start point P1 of the taper of the first resin 62a, a midpoint P2 of the first resin 62a (the midpoint in the distal-proximal direction), a boundary point P3 between the first resin 62a and the first radiopaque marker 51, a point midway (same as above) between the start point P1 and the midpoint P2 (hereinafter referred to as the first point P4), and a point midway (same as above) between the midpoint P2 and the boundary point P3 (hereinafter referred to as the second point P5). The start point P1 of the taper of the first resin 62a is the point located most proximally within the region where the outer diameter of the first resin 62a exceeds the maximum outer diameter of the first sheath 45 in the region where the first resin 62a is formed. The maximum outer diameter of the first sheath 45 here refers to the maximum outer diameter of the first sheath 45 of the individual sheath portion 43 in the section from the boundary with the sheath branch portion 42 to the boundary with the first radiopaque marker 51. The phrase "the outer peripheral surface of the first resin 62a tapers toward the proximal side" means that the outer diameter of the first resin 62a varies so that at least the average outer diameter in the section from the boundary point P3 to the midpoint P2 decreases in this order: the average outer diameter in the section from the second point P5 to the first point P4; the average outer diameter in the section from the midpoint P2 to the starting point P1. Therefore, the outer diameter of the first resin 62a may decrease continuously or stepwise over a section spanning substantially the entire length of the first resin 62a (for example, the section from the boundary point P3 to the starting point P1). Furthermore, the outer diameter of the first resin 62a may be constant or may increase or decrease over a section spanning a portion of the length of the first resin 62a (the outer peripheral surface of the first resin 62a may be curved and include irregularities in the radial direction). Similarly, in the second resin, the points corresponding to the above starting point P1 to boundary point P3 are respectively referred to as the starting point, first point, midpoint, second point, and boundary point (not shown). "The outer peripheral surface of the second resin tapers in diameter toward the proximal side" means that the outer diameter of the second resin changes so that at least the average outer diameter in the section from the boundary point to the midpoint, the average outer diameter in the section from the second point to the first point, and the average outer diameter in the section from the midpoint to the starting point decrease in that order. With this configuration, when the inner sheath 20 is pulled out from the stent 200, the step portion 28 between the proximal end of the first radiopaque marker 51 and the first proximal adjacent portion 27 (or the step portion between the proximal end of the second radiopaque marker 52 and the second proximal adjacent portion) can be prevented from interfering with the stent 200. In the present embodiment, the stent delivery device 100 satisfies both the fifth and sixth conditions. With this configuration, when the inner sheath 20 is pulled out from the stent 200, the step portion 28 between the proximal end of the first radiopaque marker 51 and the first proximal adjacent portion 27 can be prevented from interfering with the stent 200, and the step portion between the proximal end of the second radiopaque marker 52 and the second proximal adjacent portion can be prevented from interfering with the stent 200. The first resin 62a and the second resin may be, for example, cyanoacrylate, epoxy resin, urethane resin, or the like. The first resin 62a and the second resin may be made of the same type of resin material, or may be made of different resin materials.

[0038] The first resin 62a is applied, for example, in a 360-degree circumferential manner along the step portion 28 between the proximal end of the first radiopaque marker 51 and the first proximal adjacent portion 27. The second resin is applied, for example, in a 360-degree circumferential manner along the step portion between the proximal end of the second radiopaque marker 52 and the second proximal adjacent portion. 6(a) and 6(b), the maximum outer diameter of the first resin 62a is approximately equal to the outer diameter of the first radiopaque marker 51, and the minimum outer diameter of the first resin 62a is approximately equal to the outer diameter of the inner sheath body 31. The diameter of the first resin 62a gradually decreases from the proximal end of the first radiopaque marker 51 toward the outer peripheral surface of the first proximal adjacent portion 27. Similarly, the maximum outer diameter of the second resin is approximately equal to the outer diameter of the second radiopaque marker 52 , and the minimum outer diameter of the second resin is approximately equal to the outer diameter of the inner sheath body 31 . Furthermore, the outer diameter of the distal end of the first radiopaque marker 51 is larger than the outer diameter of the first distal adjacent portion 26, which is the portion of the first sheath 45 adjacent to the distal side of the formation region of the first radiopaque marker 51, and a resin material 62b is filled in the step portion between the distal end of the first radiopaque marker 51 and the first distal adjacent portion 26. The resin material 62b is applied in a circumferential manner along the step portion, and its outer diameter is set to a dimension slightly larger than the outer diameter of the first radiopaque marker 51. Similarly, the outer diameter of the distal end of the second radiopaque marker 52 is larger than the outer diameter of a second distal adjacent portion, which is a portion of the second sheath 47 adjacent to the distal side of the formation region of the second radiopaque marker 52, and a resin material 62b is filled in the step portion between the distal end of the second radiopaque marker 52 and the second distal adjacent portion. The resin material 62b is applied in a circumferential manner along the step portion, and its outer diameter is set to a dimension slightly larger than the outer diameter of the second radiopaque marker 52.

[0039] In this embodiment, the first radiopaque marker 51 (plurality of first tubular portions 51a) and its surrounding structure, and the second radiopaque marker 52 (plurality of second tubular portions 52a) and its surrounding structure are configured in substantially the same manner. For this reason, in Figures 5, 6(a) and 6(b), the first radiopaque marker 51 (plurality of first tubular portions 51a) and its surrounding structure are selectively shown, and the second radiopaque marker 52 (plurality of second tubular portions 52a) and its surrounding structure are not shown. More specifically, as an example, the first radiopaque marker 51 and the second radiopaque marker 52 are formed to have the same shape and dimensions as each other, and the second constricted portion of the second sheath 47 is formed to have approximately the same shape and dimensions as the first constricted portion 32 of the first sheath 45. The first tubular portions 51a and the second tubular portions 52a are formed to have the same shape and dimensions, and the number of the first tubular portions 51a and the number of the second tubular portions 52a are equal to each other.

[0040] However, the present invention is not limited to this example, and the first radiopaque marker 51 and the second radiopaque marker 52 may be formed to have different shapes and dimensions. Therefore, the second constricted portion of the second sheath 47 may be formed to have a different shape and dimensions from the first constricted portion 32 of the first sheath 45. Furthermore, the first tubular portion 51a and the second tubular portion may be formed to have different shapes and dimensions, and the number of first tubular portions 51a and the number of second tubular portions may be different from each other.

[0041] The outer diameter and inner diameter of the first radiopaque marker 51 (first tubular portion 51a) are each constant, for example, regardless of the position in the axial direction. The outer diameter of the first radiopaque marker 51 (first tubular portion 51a) is not particularly limited, but is preferably 0.5 mm or more and 3.0 mm or less. The inner diameter of the first radiopaque marker 51 (first tubular portion 51a) is not particularly limited, but is preferably 0.1 mm or more and 2.0 mm or less. The wall thickness of the first radiopaque marker 51 (first tubular portion 51a) is preferably, for example, equal to or less than the wire diameter of the wire member constituting the stent 200. More specifically, the wall thickness of the first radiopaque marker 51 (first tubular portion 51a) is preferably 0.01 mm or more and 1 mm or less. Similarly, the outer diameter and inner diameter of the second radiopaque marker 52 (second tubular portion 52a) are each constant, for example, regardless of the position in the axial direction. The outer diameter of the second radiopaque marker 52 (second tubular portion 52a) is not particularly limited, but is preferably 0.5 mm or more and 3.0 mm or less. The inner diameter of the second radiopaque marker 52 (second tubular portion 52a) is not particularly limited, but is preferably 0.1 mm or more and 2.0 mm or less. The wall thickness of the second radiopaque marker 52 (second tubular portion 52a) is preferably, for example, equal to or less than the wire diameter of the wire member constituting the stent 200. More specifically, the wall thickness of the second radiopaque marker 52 (second tubular portion) is preferably 0.01 mm or more and 1 mm or less.

[0042] Examples of materials that can be used for the inner sheath body 31 include various resin materials such as polyolefins such as polyethylene and polypropylene, polyvinyl chloride, polyurethane, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamide, polyether polyamide, polyester polyamide, polyether ether ketone, polyetherimide, fluorine-based resins such as polytetrafluoroethylene and tetrafluoroethylene-hexafluoropropylene copolymer, and various thermoplastic elastomers such as polyolefins, polyurethanes, polyesters, polyamides, and polybutadiene. Two or more of these materials can also be used in combination.

[0043] The outer diameter of the inner sheath body 31 is not particularly limited, but is preferably 0.1 mm or more and 2 mm or less. The inner diameter of the inner sheath body 31 is not particularly limited, but is preferably 0.05 mm or more and 1 mm or less. Furthermore, the total length of the inner sheath body 31 is not particularly limited, but is preferably 500 mm or more and 3000 mm or less.

[0044] An example of a method of using the stent delivery device 100 of this embodiment will be described below with reference to Figures 8(a) to 10(c). In Figures 10(a) to 10(c), the stent 200 is shown by a two-dot chain line. As an example, the following will describe a case where the stent delivery device 100 is used in a procedure for placing a stent 200 inside a bile duct 510. The description will be given starting from a state in which the distal end of the insertion section of the endoscope 400 is placed in advance inside the duodenum (not shown) near the duodenal papilla (papilla of Vater), a needle hole is formed in the bile duct, and the tip of the guidewire 300 is anchored (locked) to the needle hole. More specifically, the first guidewire 300a is anchored to the needle hole in the left hepatic duct 512, and the second guidewire 300b is anchored to the needle hole in the right hepatic duct 513 (see FIG. 8(a)). First, the stent delivery device 100 is introduced along the guidewire 300. More specifically, first, the first sheath 45 is inserted over the first guidewire 300a, and the second sheath 47 is inserted over the second guidewire 300b. The inner sheath 20 is slid from the proximal side to the distal side along the axial direction of the guidewire 300, and the distal end of the inner sheath 20 and the outer sheath 10 are advanced to the bifurcation 511a of the common hepatic duct 511 (see FIG. 8(b)). Next, the outer sheath 10 is retracted proximally, thereby exposing the individual sheath portion 43 of the inner sheath 20 from the outer sheath 10 (see FIG. 9(a)). More specifically, for example, the outer sheath 10 is lowered to a position proximal to and near the first radiopaque marker 51 and the second radiopaque marker 52. Then, the first sheath 45 of the individual sheath portion 43 is fed into the left hepatic duct 512 along the first guidewire 300a, and the second sheath 47 of the individual sheath portion 43 is fed into the right hepatic duct 513 along the second guidewire 300b (FIG. 9(b)). The wire member 250 is then pulled proximally, thereby untying the string member 240 from the stent 200. This releases the string member 240 from its restraint on the stent 200, causing the first branch vessel 220 and the second branch vessel 230 of the stent 200 to change from their contracted state to their deployed state. The stent mounting portion 21 of the inner sheath 20 is then entirely exposed from the outer sheath 10, causing the main vessel 210 of the stent 200 to change from its contracted state to its deployed state. After the entire stent 200 has changed from its contracted state to its deployed state in this way, the inner sheath 20 and the outer sheath 10 are removed from the body cavity. In this manner, the stent 200 is placed inside the bile duct 510 .

[0045] As described above, a first radiopaque marker 51 is provided on the first sheath 45 of the individual sheath portion 43 at a position corresponding to the stent branch portion 211, and a second radiopaque marker 52 is provided on the second sheath 47 of the individual sheath portion 43 at a position corresponding to the stent branch portion 211. Therefore, under X-ray (radiation) observation, the user can easily grasp the positions of the first sheath 45 and the second sheath 47, and further the positions of the first branch tube 220 and the second branch tube 230 of the stent 200, using the positions of the first radiopaque marker 51 and the second radiopaque marker 52 as indicators. This allows the stent 200 to be placed more reliably at the desired site.

[0046] More specifically, in this embodiment, the first radiopaque marker 51 and the second radiopaque marker 52 are set to have the same length dimension (dimension in the tip-proximal direction). Also, as shown in Fig. 2(b), the first radiopaque marker 51 and the second radiopaque marker 52 are arranged at the same position in the tip-proximal direction. 10(a) and 10(b), in this embodiment, the first radiopaque marker 51 and the second radiopaque marker 52 are arranged approximately parallel to and close to each other until the stent bifurcation 211 reaches the bifurcation 511a of the bile duct 510, and are visually recognized as an integrated shape (for example, a single rectangle) under X-ray (radiation) observation. This allows the user to understand that the stent bifurcation 211 has not yet reached the bifurcation 511a. Then, when the stent bifurcation 211 reaches the bifurcation 511a of the bile duct 510, the distal ends of the first radiopaque marker 51 and the second radiopaque marker 52 enter the left hepatic duct 512 and the right hepatic duct 513, respectively, and are visually recognized as two separated (spaced apart) parts (forming a Y-shape overall) under X-ray (radiation) observation (see FIG. 10(c)). This allows the user to easily understand that the stent branch 211 is aligned with the branch 511a, the first branch duct 220 is positioned in the left hepatic duct 512, and the second branch duct 230 is positioned in the right hepatic duct 513. In this way, according to this embodiment, the Y-shaped stent 200 can be placed satisfactorily in a bifurcated body cavity.

[0047] As described above, in this embodiment, a small gap 51c is formed between the plurality of (e.g., two) first tubular portions 51a in the distal-proximal direction. Similarly, a small gap 52c is formed between the plurality of (e.g., two) second tubular portions 52a in the distal-proximal direction. With this configuration, the first sheath 45 can be easily bent within the region where the first radiopaque marker 51 is formed, and the second sheath 47 can be easily bent within the region where the second radiopaque marker 52 is formed. Therefore, when the stent bifurcation portion 211 reaches the bifurcation portion 511a of the bile duct 510, the aggregate of the first radiopaque marker 51 and the second radiopaque marker 52 can form a Y-shape that branches into two branches from the common hepatic duct 511 toward the left hepatic duct 512 and the right hepatic duct 513, as shown in FIG. 10(c).

[0048] As described above, in the first sheath 45, a boundary portion (gap 51c in this embodiment) between the distal first tubular portion 51aa and the proximal first tubular portion 51ab is disposed at a position corresponding to the stent bifurcation portion 211. That is, of the first radiopaque marker 51, the distal first tubular portion 51aa is disposed in the first branch vessel 220, while the proximal first tubular portion 51ab is disposed in the main vessel 210. Similarly, in the second sheath 47, a boundary (a gap in this embodiment) between the distal second tubular portion 52aa and the proximal second tubular portion 52ab is disposed at a position corresponding to the stent bifurcation portion 211. That is, of the second radiopaque marker 52, the distal second tubular portion is disposed in the second branch vessel 230, while the proximal second tubular portion is disposed in the main vessel 210. According to this configuration, when the stent bifurcation 211 reaches the bifurcation 511a of the bile duct 510, the distal first tubular portion 51aa and the distal second tubular portion 52aa are inserted into the left hepatic duct 512 and the right hepatic duct 513, respectively, and gradually move away from each other distally, while the proximal first tubular portion 51ab and the proximal second tubular portion 52ab extend parallel to each other in the common hepatic duct 511. Therefore, under X-ray (radiation) observation, the aggregate of the first radiopaque marker 51 and the second radiopaque marker 52 can form a bifurcated Y-shape extending from the common hepatic duct 511 toward the left hepatic duct 512 and the right hepatic duct 513. In addition, in Figures 10(a) to 10(c), the boundary (gap 51c) between the distal first tubular portion 51aa and the proximal first tubular portion 51ab and the boundary (gap) between the distal second tubular portion 52aa and the proximal second tubular portion 52ab are not shown.

[0049] Furthermore, since the boundary between the distal first tubular portion 51aa and the proximal first tubular portion 51ab is a gap 51c, the first radiopaque marker 51 can be easily bent starting from the boundary (gap 51c). Similarly, the second radiopaque marker 52 can also be easily bent starting from the boundary (gap). Therefore, the aggregate of the first radiopaque marker 51 and the second radiopaque marker 52 can form a Y-shape that branches into two branches from the common hepatic duct 511 toward the left hepatic duct 512 and the right hepatic duct 513.

[0050] Furthermore, in this embodiment, as shown in Figure 3(a), the sheath branching portion 42 is located proximal to the intermediate portions of the first radiopaque marker 51 and the second radiopaque marker 52 in the tip-to-base direction. According to this configuration, when the stent 200 is attached to the inner sheath 20, the sheath branch 42 can be positioned sufficiently proximal to the stent branch 211 of the stent 200. This ensures sufficient room for the first sheath 45 and the second sheath 47 of the individual sheath portion 43 to bend in directions away from each other toward the distal side near the stent branch 211. Therefore, for example, even if the angle formed between the left hepatic duct 512 and the right hepatic duct 513 is large, the first sheath 45 and the second sheath 47 can be smoothly inserted into the left hepatic duct 512 and the right hepatic duct 513, respectively.

[0051] Preferably, the sheath branch portion 42 is located proximal to the entire first radiopaque marker 51 and the entire second radiopaque marker 52 in the distal-proximal direction. According to this configuration, it is possible to more effectively ensure room for the first sheath 45 and the second sheath 47 of the individual sheath portion 43 to bend in directions away from each other toward the distal side in the vicinity of the stent bifurcation portion 211.

[0052] <Variation 1> Next, Modification 1 will be described with reference to Figures 11 to 12(b). The stent delivery device 100 according to this modification differs from the stent delivery device 100 according to the above embodiment in the points described below, but in other respects is configured similarly to the stent delivery device 100 according to the above embodiment.

[0053] As described above, the first radiopaque marker 51 is formed in a tubular shape with a larger diameter than the first sheath 45, and the first sheath 45 has a first distal adjacent portion 26 which is a portion of the first sheath 45 adjacent to the distal side of the region where the first radiopaque marker 51 is formed, and a first proximal adjacent portion 27 which is a portion of the first sheath 45 adjacent to the proximal side of the region where the first radiopaque marker 51 is formed. Similarly, the second radiopaque marker 52 is formed in a tubular shape with a larger diameter than the second sheath 47, and the second sheath 47 has a second distal adjacent portion which is a portion of the second sheath 47 adjacent to the distal side of the region where the second radiopaque marker 52 is formed, and a second proximal adjacent portion which is a portion of the second sheath 47 adjacent to the proximal side of the region where the second radiopaque marker 52 is formed. Here, the seventh condition is that the radial dimension of the step between the first distal adjacent portion 26 and the distal end of the first radiopaque marker 51 is the first step dimension (dimension H1 shown in Figure 12(a)), and the radial dimension of the step between the proximal end of the first radiopaque marker 51 and the first proximal adjacent portion 27 is the second step dimension (dimension H2 shown in Figure 12(b)).The seventh condition is that the second step dimension H2 is less than or equal to 1 / 2 of the first step dimension H1. Furthermore, the eighth condition is that the radial dimension of the step between the second distal adjacent portion and the distal end of the second radiopaque marker 52 is the third step dimension (not shown), and the radial dimension of the step between the proximal end of the second radiopaque marker 52 and the second proximal adjacent portion is the fourth step dimension (not shown), and the fourth step dimension is less than 1 / 2 of the second step dimension. In this modified example, the stent delivery device 100 satisfies at least one of the seventh and eighth conditions. With this configuration, at least one of the step between the distal end of the first radiopaque marker 51 and the first distal adjacent portion 26 and the step between the distal end of the second radiopaque marker 52 and the second distal adjacent portion can be sufficiently ensured. That is, the outer diameter of the distal end of at least one of the first radiopaque marker 51 and the second radiopaque marker 52 can be sufficiently ensured, thereby improving visibility under X-ray (radiation) observation. Therefore, using the first radiopaque marker 51 and the second radiopaque marker 52, which are separated into a Y shape and form a Y shape as a whole, as indicators, it can be more easily determined that the first branch duct 220 is located in the left hepatic duct 512 and the second branch duct 230 is located in the right hepatic duct 513. On the other hand, at least one of the step between the proximal end of the first radiopaque marker 51 and the first proximal adjacent portion 27 and the step between the proximal end of the second radiopaque marker 52 and the second proximal adjacent portion can be made sufficiently small. This makes it possible to prevent the proximal end of at least one of the first radiopaque marker 51 and the second radiopaque marker 52 from interfering with the stent 200 when the inner sheath 20 is removed from the stent 200. This makes it possible to more reliably place the stent 200 at a desired site in a biological lumen.

[0054] 11, in this modified example, as in the above embodiment, the first radiopaque marker 51 is composed of a plurality of (e.g., two) first tubular portions 51a connected in a proximal to distal direction. Similarly, the second radiopaque marker 52 is composed of a plurality of (e.g., two) second tubular portions 52a connected in a proximal to distal direction. Here, in the case of this modified example, unlike the above embodiment, the eleventh condition is that the thickness T1 (see Figure 12(a)) of the distal first tubular portion 51aa, which is the first tubular portion 51a located most distally among the multiple first tubular portions 51a, is greater than the thickness T2 (see Figure 12(b)) of the proximal first tubular portion 51ab, which is the first tubular portion 51a located most proximal. Furthermore, the second radiopaque marker 52 is composed of a plurality of second tubular portions 52a connected in the distal-proximal direction, and the thickness of the distal second tubular portion 52aa, which is the second tubular portion 52a located most distally among the plurality of second tubular portions 52a, is greater than the thickness of the proximal second tubular portion 52ab, which is the second tubular portion 52a located most proximal. In this modified example, the stent delivery device 100 satisfies at least one of the eleventh and twelfth conditions. Here, "the thickness of the distal first tubular portion 51aa is greater than the thickness of the proximal first tubular portion 51ab" means that the average thickness of the distal first tubular portion 51aa is greater than the average thickness of the proximal first tubular portion 51ab. Similarly, "the thickness of the distal second tubular portion 52aa is greater than the thickness of the proximal second tubular portion 52ab" means that the average thickness of the distal second tubular portion 52aa is greater than the average thickness of the proximal second tubular portion 52ab. With this configuration, the visibility under X-ray (radiation) observation can be further improved at the distal end portion (distal first tubular portion 51aa or distal second tubular portion 52aa) of at least one of the first radiopaque marker 51 and the second radiopaque marker 52. On the other hand, at least one of the step between the proximal end of the first radiopaque marker 51 (the proximal end of the proximal first tubular portion 51ab) and the first proximal adjacent portion 27 and the step between the proximal end of the second radiopaque marker 52 (the proximal end of the proximal second tubular portion 52ab) and the second proximal adjacent portion can be made sufficiently small. Therefore, when the inner sheath 20 is pulled out from the stent 200, it is possible to prevent the proximal end of at least one of the first radiopaque marker 51 and the second radiopaque marker 52 from interfering with the stent 200.

[0055] In this modified example, the stent delivery device 100 satisfies both the seventh and eighth conditions. With this configuration, the step between the distal end of the first radiopaque marker 51 and the first distal adjacent portion 26 and the step between the distal end of the second radiopaque marker 52 and the second distal adjacent portion can be sufficiently ensured. That is, the outer diameter of the distal end of each of the first radiopaque marker 51 and the second radiopaque marker 52 can be sufficiently ensured, thereby improving visibility under X-ray (radiation) observation. Therefore, using the first radiopaque marker 51 and the second radiopaque marker 52, which form a Y-shape as a whole, as an indicator, it can be more easily determined that the first branch duct 220 is located in the left hepatic duct 512 and the second branch duct 230 is located in the right hepatic duct 513. On the other hand, the step between the proximal end of the first radiopaque marker 51 and the first proximal adjacent portion 27 and the step between the proximal end of the second radiopaque marker 52 and the second proximal adjacent portion can be made sufficiently small. This makes it possible to prevent the proximal ends of the first radiopaque marker 51 and the second radiopaque marker 52 from interfering with the stent 200 when the inner sheath 20 is pulled out of the stent 200. This makes it possible to more reliably place the stent 200 at a desired site in a biological lumen.

[0056] Furthermore, in the case of this modification, the stent delivery device 100 satisfies both the eleventh and twelfth conditions. With this configuration, the visibility under X-ray (radiation) observation can be further improved at the distal end portions (distal first tubular portion 51aa and distal second tubular portion 52aa) of the first radiopaque marker 51 and the second radiopaque marker 52. On the other hand, it is possible to sufficiently reduce the step between the proximal end of the first radiopaque marker 51 (the proximal end of the proximal-side first tubular portion 51ab) and the first proximal adjacent portion 27, and the step between the proximal end of the second radiopaque marker 52 (the proximal end of the proximal-side second tubular portion 52ab) and the second proximal adjacent portion. Therefore, when the inner sheath 20 is removed after the stent 200 is deployed, it is possible to prevent the proximal ends of the first radiopaque marker 51 and the second radiopaque marker 52 from interfering with the stent 200.

[0057] Also in this modified example, as in the above embodiment, the outer peripheral surface of the first resin 62a at the step 28 between the proximal end of the first radiopaque marker 51 and the first proximal adjacent portion 27 tapers in diameter proximally. Similarly, the outer peripheral surface of the second resin (not shown) at the step (not shown) between the proximal end of the second radiopaque marker 52 and the second proximal adjacent portion tapers in diameter proximally. Therefore, when the inner sheath 20 is pulled out from the stent 200, the proximal ends of the first radiopaque marker 51 and the second radiopaque marker 52 can be more reliably prevented from interfering with the stent 200.

[0058] More specifically, in this modified example, the first radiopaque marker 51 (plurality of first tubular portions 51a) and its surrounding structure, and the second radiopaque marker 52 (plurality of second tubular portions 52a) and its surrounding structure are configured in substantially the same manner. For this reason, in Figures 11 to 12(b), the first radiopaque marker 51 (plurality of first tubular portions 51a) and its surrounding structure are selectively shown, and the second radiopaque marker 52 (plurality of second tubular portions 52a) and its surrounding structure are not shown. However, the present invention is not limited to this example, and the first radiopaque marker 51 and the second radiopaque marker 52 may be formed to have different shapes and dimensions.

[0059] In this modified example, as in the above embodiment, the first radiopaque marker 51 is composed of two first tubular portions 51a (a distal first tubular portion 51aa and a proximal first tubular portion 51ab). Therefore, the radial dimension of the step between the first distal adjacent portion 26 and the distal end of the distal first tubular portion 51aa is a first step dimension H1, and the radial dimension of the step between the proximal end of the proximal first tubular portion 51ab and the first proximal adjacent portion 27 is a second step dimension H2. Similarly, the second radiopaque marker 52 is composed of two second tubular portions 52a (a distal second tubular portion 52aa and a proximal second tubular portion 52ab). Therefore, the radial dimension of the step between the second proximal adjacent portion and the distal end of the distal second tubular portion 52aa is a third step dimension, and the radial dimension of the step between the proximal end of the proximal second tubular portion 52ab and the second proximal adjacent portion is a fourth step dimension.

[0060] 11, in this modification, a gap 51c (a boundary between the distal first tubular portion 51aa and the proximal first tubular portion 51ab) is also formed between the distal first tubular portion 51aa and the proximal first tubular portion 51ab in the tip-to-proximal direction. For example, a third resin 64a is filled in the gap 51c. For example, the outer peripheral surface of the third resin 64a tapers toward the proximal side. With this configuration, when the inner sheath 20 is removed, the step formed at the boundary between the proximal end of the distal first tubular portion 51aa and the distal end of the proximal first tubular portion 51ab can be prevented from interfering with the stent 200.

[0061] Similarly, in this modified example, a gap (a boundary between the distal second tubular portion 52aa and the proximal second tubular portion 52ab) is formed between the distal second tubular portion 52aa and the proximal second tubular portion 52ab in the tip-to-base direction, and this gap is filled with, for example, a fourth resin (not shown). The outer circumferential surface of the fourth resin tapers in diameter toward the proximal side, for example. With this configuration, when the inner sheath 20 is removed, the step formed at the boundary between the proximal end of the distal second tubular portion 52aa and the distal end of the proximal second tubular portion 52ab can be prevented from interfering with the stent 200.

[0062] In this modification, the outer diameter and inner diameter of the distal first tubular portion 51aa are constant regardless of the position in the axial direction. That is, the wall thickness T1 of the distal first tubular portion 51aa is constant regardless of the position in the axial direction. Similarly, the outer diameter and inner diameter of the proximal first tubular portion 51ab are constant regardless of the position in the axial direction. That is, the wall thickness T2 of the proximal first tubular portion 51ab is constant regardless of the position in the axial direction. However, the present invention is not limited to this example, and the outer diameter of the distal first tubular portion 51aa or the outer diameter of the proximal first tubular portion 51ab may, for example, be tapered toward the proximal side, as in variant example 2 described below (the wall thickness of the distal first tubular portion 51aa or the wall thickness of the proximal first tubular portion 51ab may be reduced toward the proximal side). Similarly, the outer diameter and inner diameter of the distal second tubular portion 52aa are constant regardless of the position in the axial direction. That is, the wall thickness of the distal second tubular portion 52aa is constant regardless of the position in the axial direction. Similarly, the outer diameter and inner diameter of the proximal second tubular portion 52ab are constant regardless of the position in the axial direction. That is, the wall thickness of the proximal second tubular portion 52ab is constant regardless of the position in the axial direction. However, the present invention is not limited to this example, and the outer diameter of the distal second tubular portion 52aa or the outer diameter of the proximal second tubular portion 52ab may, for example, be tapered toward the proximal side, as in variant example 2 described below (the wall thickness of the distal second tubular portion 52aa or the wall thickness of the proximal second tubular portion 52ab may be reduced toward the proximal side).

[0063] The thickness T1 of the distal first tubular portion 51aa is, for example, preferably 1.2 to 5 times the thickness T2 of the proximal first tubular portion 51ab, and more preferably 2 to 4 times the thickness T2 of the proximal first tubular portion 51ab. Similarly, the thickness of the distal second tubular portion 52aa is preferably, for example, 1.2 to 5 times the thickness of the proximal second tubular portion 52ab, and more preferably, 2 to 4 times the thickness of the proximal second tubular portion 52ab.

[0064] In the axial direction, the length dimension of the distal first tubular portion 51aa is, for example, greater than the length dimension of the proximal first tubular portion 51ab. This makes it possible to improve the visibility of the first radiopaque marker 51 under X-ray (radiation) observation while suppressing interference between the proximal end of the first radiopaque marker 51 and the stent 200. However, the present invention is not limited to this example, and the length dimension of the distal first tubular portion 51aa in the axial direction may be equal to the length dimension of the proximal first tubular portion 51ab.

[0065] Similarly, in the axial direction, the length dimension of the distal second tubular portion 52aa is, for example, greater than the length dimension of the proximal second tubular portion 52ab. This makes it possible to improve the visibility of the second radiopaque marker 52 under X-ray (radiation) observation while suppressing interference between the proximal end of the second radiopaque marker 52 and the stent 200. However, the present invention is not limited to this example, and the length dimension of the distal second tubular portion 52aa in the axial direction may be equal to the length dimension of the proximal second tubular portion 52ab.

[0066] Here, in the case of this modification, a boundary portion (gap 51c in the case of this modification) between the distal first tubular portion 51aa and the proximal first tubular portion 51ab is also disposed in the first sheath 45 at a position corresponding to the stent bifurcation portion 211. That is, of the first radiopaque marker 51, the distal first tubular portion 51aa is disposed in the first branch vessel 220, while the proximal first tubular portion 51ab is disposed in the main vessel 210. Similarly, in the second sheath 47, a boundary portion (gap 52c in this modification) between the distal second tubular portion 52aa and the proximal second tubular portion 52ab is disposed at a position corresponding to the stent bifurcation portion 211. That is, of the second radiopaque marker 52, the distal second tubular portion 52aa is disposed in the second branch vessel 230, while the proximal second tubular portion 52ab is disposed in the main vessel 210. According to this configuration, when the stent bifurcation 211 reaches the bifurcation 511a of the bile duct 510, the distal first tubular portion 51aa and the distal second tubular portion 52aa are inserted into the left hepatic duct 512 and the right hepatic duct 513, respectively, and gradually move away from each other distally, while the proximal first tubular portion 51ab and the proximal second tubular portion 52ab extend parallel to each other in the common hepatic duct 511. Therefore, under X-ray (radiation) observation, the aggregate of the first radiopaque marker 51 and the second radiopaque marker 52 can form a bifurcated Y-shape extending from the common hepatic duct 511 toward the left hepatic duct 512 and the right hepatic duct 513.

[0067] Furthermore, in this modified example, the boundary between the distal first tubular portion 51aa and the proximal first tubular portion 51ab is a gap 51c, so the first radiopaque marker 51 can be easily bent starting from the boundary (gap 51c). Similarly, the second radiopaque marker 52 can be easily bent starting from the boundary (gap 52c). Therefore, the aggregate of the first radiopaque marker 51 and the second radiopaque marker 52 can form a Y-shape that branches into two branches from the common hepatic duct 511 toward the left hepatic duct 512 and the right hepatic duct 513.

[0068] The present invention is not limited to an example in which the first radiopaque marker 51 is composed of two first tubular portions 51a (the distal first tubular portion 51aa and the proximal first tubular portion 51ab), and the first radiopaque marker 51 may be composed of, for example, three or more first tubular portions 51a. In this case, of the three or more first tubular portions 51a, the outer diameter of one or more first tubular portions 51a disposed between the distal first tubular portion 51aa and the proximal first tubular portion 51ab in the tip-to-base direction is preferably smaller than the outer diameter of the distal first tubular portion 51aa and larger than the outer diameter of the proximal first tubular portion 51ab. In other words, of the multiple first tubular portions 51a constituting the first radiopaque marker 51, it is preferable that the first tubular portion 51a disposed closer to the proximal side has a smaller outer diameter. Alternatively, it is also preferable that the outer diameter of the one or more first tubular portions 51a arranged between the distal first tubular portion 51aa and the proximal first tubular portion 51ab is, for example, equal to the outer diameter of the distal first tubular portion 51aa or equal to the outer diameter of the proximal first tubular portion 51ab.

[0069] Similarly, the second radiopaque marker 52 is not limited to the example in which it is composed of two second tubular portions 52a, and the second radiopaque marker 52 may be composed of, for example, three or more second tubular portions 52a. In this case, of the three or more second tubular portions 52a, the outer diameter of one or more second tubular portions 52a disposed between the distal second tubular portion 52aa and the proximal second tubular portion 52ab in the tip-to-proximal direction is preferably smaller than the outer diameter of the distal second tubular portion 52aa and larger than the outer diameter of the proximal second tubular portion 52ab. In other words, of the multiple second tubular portions 52a constituting the second radiopaque marker 52, it is preferable that the second tubular portion 52a disposed closer to the proximal side has a smaller outer diameter. Alternatively, it is also preferable that the outer diameter of the one or more second tubular portions 52a arranged between the distal second tubular portion 52aa and the proximal second tubular portion 52ab is, for example, equal to the outer diameter of the distal second tubular portion 52aa or equal to the outer diameter of the proximal second tubular portion 52ab.

[0070] <Variation 2> Next, Modification 2 will be described with reference to Figures 13 to 15(c). The stent delivery device 100 according to this modification differs from the stent delivery device 100 according to Modification 1 in the points described below, but is otherwise configured similarly to the stent delivery device 100 according to Modification 1.

[0071] As shown in FIGS. 13 to 14(b), in this modification, as in the first modification, the stent delivery device 100 satisfies at least one of the seventh and eighth conditions. Here, the ninth condition is that the outer diameter of the proximal end portion 51ba of the first radiopaque marker 51 tapers toward the proximal side. Similarly, the tenth condition is that the outer diameter of the proximal end portion 52ba of the second radiopaque marker 52 tapers toward the proximal side. The stent delivery device 100 satisfies at least one of the above ninth and tenth conditions. Note that the "proximal end portion 51ba of the first radiopaque marker 51" referred to here is the region proximal to the midpoint (middle in the tip-base direction) of the formation region of the first radiopaque marker 51 and including the proximal end of the first radiopaque marker 51. Similarly, the "proximal end 52ba of the second radiopaque marker 52" referred to here is the region proximal to the midpoint (middle in the tip-base direction) of the formation region of the second radiopaque marker 52 and including the proximal end of the second radiopaque marker 52. Even with this configuration, the outer diameter of the distal end portions 51bb, 52bb of at least one of the first radiopaque marker 51 and the second radiopaque marker 52 can be sufficiently secured, thereby improving visibility under X-ray (radiation) observation. On the other hand, at least one of the step between the proximal end of the first radiopaque marker 51 and the first proximal adjacent portion 27 and the step between the proximal end of the second radiopaque marker 52 and the second proximal adjacent portion can be made sufficiently small. This makes it possible to prevent the proximal end of at least one of the first radiopaque marker 51 and the second radiopaque marker 52 from interfering with the stent 200 when the inner sheath 20 is removed after the stent 200 has been deployed. This makes it possible to more reliably place the stent 200 at a desired site in a biological lumen. Furthermore, as will be described later, even when the first radiopaque marker 51 is formed of a single first tubular portion 51a, it is easy to achieve a configuration in which the second step dimension H2 is equal to or less than half the first step dimension H1. Similarly, even when the second radiopaque marker 52 is formed of a single second tubular portion 52a, it is easy to achieve a configuration in which the fourth step dimension is equal to or less than half the third step dimension.

[0072] In this modified example, the stent delivery device 100 satisfies both the ninth and tenth conditions. With this configuration, the distal ends 51bb, 52bb of the first radiopaque marker 51 and the second radiopaque marker 52 can have a sufficient outer diameter, thereby improving visibility under X-ray (radiation) observation. On the other hand, it is possible to make sufficiently small the step between the proximal end of the first radiopaque marker 51 and the first proximal adjacent portion 27, and the step between the proximal end of the second radiopaque marker 52 and the second proximal adjacent portion, respectively. This makes it possible to prevent the proximal ends of the first radiopaque marker 51 and the second radiopaque marker 52 from interfering with the stent 200 when the inner sheath 20 is removed after the stent 200 has been deployed.

[0073] More specifically, in this modified example, the first radiopaque marker 51 and its surrounding structure and the second radiopaque marker 52 and its surrounding structure are configured in substantially the same manner. For this reason, in Figures 13 to 14(b), the first radiopaque marker 51 (first tubular portion 51a) and its surrounding structure are selectively shown, and the second radiopaque marker 52 (second tubular portion 52a) and its surrounding structure are not shown. However, the present invention is not limited to this example, and the first radiopaque marker 51 and the second radiopaque marker 52 may be formed to have different shapes and dimensions.

[0074] In this modified example, the first radiopaque marker 51 is configured by a single first tubular portion 51a, as shown in Fig. 13. Therefore, in this modified example, the radial dimension of the step between the first distal adjacent portion 26 and the distal end of the first tubular portion 51a is a first step dimension H1, and the radial dimension of the step between the proximal end of the first tubular portion 51a and the first proximal adjacent portion 27 is a second step dimension H2. Similarly, the second radiopaque marker 52 is composed of one second tubular portion 52a. Therefore, in this modified example, the radial dimension of the step between the second distal adjacent portion and the distal end of the second tubular portion 52a is a third step dimension, and the radial dimension of the step between the proximal end of the second tubular portion 52a and the second proximal adjacent portion is a fourth step dimension.

[0075] In this modified example, the inner diameter of the first radiopaque marker 51 (first tubular portion 51a) is constant regardless of the position in the axial direction. The outer diameter of the proximal end of the first radiopaque marker 51 (first tubular portion 51a) tapers toward the proximal side, while the outer diameter of the portion of the first radiopaque marker 51 distal to the proximal end is constant regardless of the position in the axial direction. In other words, the thickness of the proximal end of the first radiopaque marker 51 gradually decreases toward the proximal side, while the thickness of the portion of the first radiopaque marker 51 distal to the proximal end is constant regardless of the position in the axial direction. Similarly, the inner diameter of the second radiopaque marker 52 (second tubular portion 52a) is constant regardless of the position in the axial direction. The outer diameter of the proximal end of the second radiopaque marker 52 (second tubular portion 52a) tapers proximally, while the outer diameter of the portion of the second radiopaque marker 52 distal to the proximal end is constant regardless of the position in the axial direction. In other words, the thickness of the proximal end of the second radiopaque marker 52 gradually decreases proximally, while the thickness of the portion of the second radiopaque marker 52 distal to the proximal end is constant regardless of the position in the axial direction. According to this configuration, the visibility of the distal end portions 51bb, 52bb of the first radiopaque marker 51 and the second radiopaque marker 52 under X-ray (radiation) observation can be further improved. On the other hand, the step between the proximal end of the first radiopaque marker 51 and the first proximal adjacent portion 27 and the step between the proximal end of the second radiopaque marker 52 and the second proximal adjacent portion can be made sufficiently small. Therefore, when the inner sheath 20 is removed after the stent 200 is deployed, it is possible to prevent the proximal ends of the first radiopaque marker 51 and the second radiopaque marker 52 from interfering with the stent 200.

[0076] However, the present invention is not limited to this example, and the overall outer diameter of the first radiopaque marker 51 in the proximal-tip direction may taper proximally. Similarly, the overall outer diameter of the second radiopaque marker 52 in the proximal-tip direction may taper proximally. Also, in this modified example, as in the above embodiment and modified example 1, the first radiopaque marker 51 may be composed of a plurality of first tubular portions 51a, and the second radiopaque marker 52 may be composed of a plurality of second tubular portions 52a. When the first radiopaque marker 51 is composed of multiple first tubular portions 51a, it is sufficient that at least the proximal end portion of the proximal first tubular portion 51ab has a tapered diameter toward the proximal side. For example, the outer diameter of the other first tubular portions 51a, including the distal first tubular portion 51aa, may be constant regardless of their axial position, or may have a tapered diameter toward the proximal side. Similarly, when the second radiopaque marker 52 is composed of multiple second tubular portions 52a, it is sufficient that at least the proximal end portion of the proximal second tubular portion 52ab tapers in diameter toward the proximal side; for example, the outer diameter of the other second tubular portions 52a, including the distal second tubular portion 52aa, may be constant regardless of their axial position, or may taper in diameter toward the proximal side.

[0077] In this modified example, the second step dimension H2 is preferably equal to or smaller than 1 / 2 of the first step dimension H1, and more preferably equal to or smaller than 1 / 3 of the first step dimension H1. Similarly, the fourth step dimension is preferably 1 / 2 or less of the third step dimension, and more preferably 1 / 3 or less of the third step dimension.

[0078] In this modification, the proximal end 51ba of the first radiopaque marker 51 is disposed in the first sheath 45 at a position corresponding to the stent bifurcation 211. That is, at least the distal end 51bb of the first radiopaque marker 51 is disposed in the first branch tube 220. Similarly, in the second sheath 47, the proximal end 52ba of the second radiopaque marker 52 is disposed at a position corresponding to the stent bifurcation 211. That is, at least the distal end 52bb of the second radiopaque marker 52 is disposed in the second branch vessel 230. Here, "the proximal end 51ba of the first radiopaque marker 51 is positioned at a position corresponding to the stent branch portion 211" means that when the stent 200 is attached to the inner sheath 20, the proximal end 51ba straddles the stent branch portion 211 in the tip-to-base direction. Similarly, "the proximal end 52ba of the second radiopaque marker 52 is positioned at a position corresponding to the stent branch 211" means that when the stent 200 is attached to the inner sheath 20, the proximal end 52ba straddles the stent branch 211 in the tip-to-base direction. 15(a) to 15(c), when the stent bifurcation 211 reaches the bifurcation 511a of the bile duct 510, the distal end 51bb of the first radiopaque marker 51 and the distal end 52bb of the second radiopaque marker 52 are arranged so as to gradually separate from each other distally, while the proximal end 51ba of the first radiopaque marker 51 and the proximal end 52ba of the second radiopaque marker 52 are arranged close to each other. Therefore, under X-ray (radiation) observation, the aggregate of the first radiopaque marker 51 and the second radiopaque marker 52 can be configured to form a roughly V-shape that branches into two branches from the common hepatic duct 511 toward the left hepatic duct 512 and the right hepatic duct 513. This allows the user to easily understand that the stent branch 211 is aligned with the branch 511a, the first branch duct 220 is positioned in the left hepatic duct 512, and the second branch duct 230 is positioned in the right hepatic duct 513. In the case of this modified example, for example, as in the above embodiment and modified example 1, the assembly of the first radiopaque marker 51 and the second radiopaque marker 52 may form a Y-shape that branches into two branches from the common hepatic duct 511 toward the left hepatic duct 512 and the right hepatic duct 513.

[0079] The present invention is not limited to the above-described embodiments, and includes various modifications and improvements as long as the object of the present invention is achieved.

[0080] For example, in the above embodiment and variant example 1, an example has been described in which the first radiopaque marker 51 and the second radiopaque marker 52 are each configured with an individual tubular portion. However, the present invention is not limited to this example, and, for example, the distal end portion of the first radiopaque marker 51 and the distal end portion of the second radiopaque marker 52 may be configured with an individual tubular portion (distal side first tubular portion 51aa and distal side second tubular portion 52aa), while the proximal end portion of the first radiopaque marker 51 and the proximal end portion of the second radiopaque marker 52 may be configured with a common tubular portion. Even with this configuration, under X-ray (radiation) observation, the assembly of the first radiopaque marker 51 and the second radiopaque marker 52 can form a Y-shape that branches into two branches from the common hepatic duct 511 toward the left hepatic duct 512 and the right hepatic duct 513.

[0081] In addition, in the above-described first modification, an example has been described in which the length dimension of the distal first tubular portion 51aa in the axial direction is greater than or equal to the length dimension of the proximal first tubular portion 51ab. However, the present invention is not limited to this example, and the length dimension of the distal second tubular portion 52aa in the axial direction may be smaller than the length dimension of the proximal second tubular portion 52ab. With this configuration, the operability (more specifically, flexibility and insertability) can be improved when inserting the formation area of ​​the first radiopaque marker 51 in the first sheath 45 into the left hepatic duct 512 (or the right hepatic duct 513).

[0082] Similarly, in the above-described first variant, an example was described in which the length dimension of the distal second tubular portion 52aa in the axial direction is greater than or equal to the length dimension of the proximal second tubular portion 52ab. However, the present invention is not limited to this example, and the length dimension of the distal second tubular portion 52aa in the axial direction may be smaller than the length dimension of the proximal second tubular portion 52ab. With this configuration, the operability (more specifically, flexibility and insertability) can be improved when inserting the formation area of ​​the second radiopaque marker 52 in the second sheath 47 into the right hepatic duct 513 (or left hepatic duct 512).

[0083] The present embodiment encompasses the following technical ideas. (1) A stent delivery device for delivering a stent into a body, the stent having a main vessel and a first branch vessel and a second branch vessel each branching from a stent bifurcation portion at the distal end of the main vessel, a long inner sheath to which the stent is attached in an exterior state; the inner sheath has a sheath main portion in which a first sheath and a second sheath are bundled together, and an individual sheath portion in which the first sheath and the second sheath are separated and which is located distal to a sheath branch portion that is a distal end of the sheath main portion, the stent is attached to the inner sheath in a state in which the first sheath of the individual sheath portion is inserted into the first branch pipe and the second sheath of the individual sheath portion is inserted into the second branch pipe, a first radiopaque marker is provided in the first sheath of the individual sheath portion at a position corresponding to the stent bifurcation portion; A stent delivery device, wherein the second sheath of the individual sheath portion has a second radiopaque marker provided at a position corresponding to the stent bifurcation portion. (2) The first condition is that the first radiopaque marker is formed in a tubular shape, the portion of the first sheath where the first radiopaque marker is provided is a first constricted portion formed with a smaller diameter than other portions, and the first radiopaque marker is fitted onto the first constricted portion; The second radiopaque marker is formed in a tubular shape, and the portion of the second sheath where the second radiopaque marker is provided is a second constricted portion formed with a smaller diameter than other portions, and the second radiopaque marker is fitted onto the second constricted portion. The stent delivery device according to (1) satisfies at least one of the first condition and the second condition. (3) The third condition is that the first condition is satisfied and the first radiopaque marker is composed of a plurality of first tubular portions connected in a distal-proximal direction; If the fourth condition is that the second condition is satisfied and the second radiopaque marker is composed of a plurality of second tubular portions connected in a distal-proximal direction, The stent delivery device according to (2) satisfies at least one of the third condition and the fourth condition. (4) The fifth condition is that the first condition is satisfied, and the outer diameter of the proximal end of the first radiopaque marker is larger than the outer diameter of a first proximal adjacent portion, which is a portion of the first sheath adjacent to the proximal side of the formation region of the first radiopaque marker, the step portion between the proximal end of the first radiopaque marker and the first proximal adjacent portion is filled with a first resin, and the outer peripheral surface of the first resin tapers in diameter toward the proximal side; When the sixth condition is that the second condition is satisfied, and the outer diameter of the proximal end of the second radiopaque marker is larger than the outer diameter of a second proximal adjacent portion which is a portion of the second sheath adjacent to the proximal side of the formation region of the second radiopaque marker, a step portion between the proximal end of the second radiopaque marker and the second proximal adjacent portion is filled with a second resin, and the outer peripheral surface of the second resin tapers in diameter toward the proximal side, The stent delivery device according to (2) or (3), which satisfies at least one of the fifth condition and the sixth condition. (5) The first radiopaque marker is formed in a tubular shape having a diameter larger than that of the first sheath, the first sheath has a first distal adjacent portion which is a portion of the first sheath adjacent to the distal side of the region where the first radiopaque marker is formed, and a first proximal adjacent portion which is a portion of the first sheath adjacent to the proximal side of the region where the first radiopaque marker is formed, and the seventh condition is that, when the radial dimension of the step between the first distal adjacent portion and the distal end of the first radiopaque marker is defined as a first step dimension and the radial dimension of the step between the proximal end of the first radiopaque marker and the first proximal adjacent portion is defined as a second step dimension, the second step dimension is equal to or less than 1 / 2 of the first step dimension; the second radiopaque marker is formed in a tubular shape having a diameter larger than that of the second sheath; The second sheath has a second distal adjacent portion which is a portion of the second sheath adjacent to the distal side of the region where the second radiopaque marker is formed, and a second proximal adjacent portion which is a portion of the second sheath adjacent to the proximal side of the region where the second radiopaque marker is formed, and the radial dimension of the step between the second distal adjacent portion and the distal end of the second radiopaque marker is defined as a third step dimension, and the radial dimension of the step between the proximal end of the second radiopaque marker and the second proximal adjacent portion is defined as a fourth step dimension, and the fourth step dimension is equal to or less than 1 / 2 of the second step dimension, as the eighth condition. The stent delivery device according to any one of (1) to (4), which satisfies at least one of the seventh condition and the eighth condition. (6) The ninth condition is that the seventh condition is satisfied and the outer diameter of the proximal end of the first radiopaque marker tapers toward the proximal side. If the eighth condition is satisfied and the outer diameter of the proximal end of the second radiopaque marker tapers toward the proximal side, then the tenth condition is: The stent delivery device according to (5) satisfies at least one of the ninth and tenth conditions. (7) The eleventh condition is that the seventh condition is satisfied, and the first radiopaque marker is composed of a plurality of first tubular portions connected in a distal-proximal direction, and the wall thickness of the distal first tubular portion, which is the first tubular portion located most distally among the plurality of first tubular portions, is greater than the wall thickness of the proximal first tubular portion, which is the first tubular portion located most proximal; If the twelfth condition is that the eighth condition is satisfied, and the second radiopaque marker is composed of a plurality of second tubular portions connected in a distal-proximal direction, and the wall thickness of the distal second tubular portion, which is the second tubular portion located most distally among the plurality of second tubular portions, is greater than the wall thickness of the proximal second tubular portion, which is the second tubular portion located most proximal, then: The stent delivery device according to (5) or (6), which satisfies at least one of the eleventh condition and the twelfth condition. (8) A stent delivery device described in any one of (1) to (7), wherein the sheath branching portion is located proximal to the intermediate portions of the first radiopaque marker and the second radiopaque marker in the tip-base direction. (8-1) A stent delivery device as described in (8), wherein the sheath branching portion is located proximal to the entirety of each of the first radiopaque marker and the second radiopaque marker in the tip-base direction. (9) The first radiopaque marker is composed of a plurality of first tubular portions connected in the distal-proximal direction, a boundary between a proximal first tubular portion, which is the first tubular portion located on the most proximal side among the plurality of first tubular portions, and another first tubular portion adjacent to the proximal first tubular portion on the distal side thereof, is disposed at a position on the first sheath corresponding to the stent bifurcation portion, The second radiopaque marker is configured by a plurality of second tubular portions connected in the distal-proximal direction, A stent delivery device according to any one of (1) to (8), wherein the boundary between a proximal second tubular portion, which is the second tubular portion located most proximally among the plurality of second tubular portions, and another second tubular portion adjacent to the proximal second tubular portion on the distal side, is positioned at a position on the second sheath corresponding to the stent branch portion. (10) In the first sheath, the proximal end portion of the first radiopaque marker is disposed at a position corresponding to the stent bifurcation portion; A stent delivery device described in any one of (1) to (9), wherein the proximal end of the second radiopaque marker is positioned in the second sheath at a position corresponding to the stent branch portion. (11) The first radiopaque marker is composed of a plurality of first tubular portions connected in a distal-proximal direction, and a gap is formed between adjacent first tubular portions; A stent delivery device described in any one of (1) to (10), wherein the second radiopaque marker is composed of a plurality of second tubular portions connected in the distal-proximal direction, and gaps are formed between adjacent second tubular portions. [Explanation of symbols]

[0084] 10 outer sheath 10a Proximal end 10b Tip 20 Inner sheath 21 Stent attachment part 22 Large diameter section 26 First distal adjacent segment 27 First proximal adjacent segment 28 Step 31 Inner sheath body 32 First constriction 38 Tip 41 Sheath main part 42 Sheath branch 43 Individual sheath section 45 First Sheath 46a 4th sheath 46b 5th sheath 47 Second Sheath 49 Third Sheath 51 First radiopaque marker 51a First tubular section 51aa Distal first tubular portion 51ab proximal first tubular portion 51ba proximal end 51bb distal end 51c gap 52 Second radiopaque marker 52a Second tubular section 52aa Distal second tubular section 52ab Proximal second tubular portion 52ba proximal end 52bb distal end 53 Third radiopaque marker 55 Radiopaque marker 62a First Resin 62b Resin material 64a Third Resin 100 Stent delivery device 200 stents 210 Master 211 Stent bifurcation 220 1st branch pipe 230 Second branch pipe 240 String members 250 Wire material 300 Guidewire 400 Endoscope 510 Bile duct 511 Common hepatic duct 511a Branch 512 Left hepatic duct 513 Right hepatic duct P1 Starting point P2 midpoint P3 boundary point P4 1st point P5 2nd location

Claims

1. A stent delivery device for delivering a stent into a body, the stent having a main vessel and a first branch vessel and a second branch vessel each branching from a stent bifurcation portion at the distal end of the main vessel, a long inner sheath to which the stent is attached in an exterior state; the inner sheath includes a sheath main portion in which a first sheath and a second sheath are bundled together, and an individual sheath portion located distal to a sheath branch portion that is a distal end of the sheath main portion and in which the first sheath and the second sheath are separated from each other; the stent is attached to the inner sheath in a state in which the first sheath of the individual sheath portion is inserted into the first branch pipe and the second sheath of the individual sheath portion is inserted into the second branch pipe, a first radiopaque marker is provided in the first sheath of the individual sheath portion at a position corresponding to the stent bifurcation portion; A stent delivery device, wherein the second sheath of the individual sheath portion is provided with a second radiopaque marker at a position corresponding to the stent bifurcation portion.

2. The first condition is that the first radiopaque marker is formed in a tubular shape, the portion of the first sheath where the first radiopaque marker is provided is a first constricted portion formed with a smaller diameter than other portions, and the first radiopaque marker is fitted onto the first constricted portion; The second radiopaque marker is formed in a tubular shape, the portion of the second sheath where the second radiopaque marker is provided is a second constricted portion formed with a smaller diameter than other portions, and the second radiopaque marker is fitted onto the second constricted portion. The stent delivery device according to claim 1 , wherein at least one of the first condition and the second condition is satisfied.

3. a third condition is that the first condition is satisfied and the first radiopaque marker is configured with a plurality of first tubular portions connected in a distal-proximal direction; If the fourth condition is that the second condition is satisfied and the second radiopaque marker is configured by a plurality of second tubular portions connected in a distal-proximal direction, The stent delivery device according to claim 2 , wherein at least one of the third condition and the fourth condition is satisfied.

4. The fifth condition is that the first condition is satisfied, and the outer diameter of the proximal end of the first radiopaque marker is larger than the outer diameter of a first proximal adjacent portion which is a portion of the first sheath adjacent to the proximal side of the formation region of the first radiopaque marker, the step portion between the proximal end of the first radiopaque marker and the first proximal adjacent portion is filled with a first resin, and the outer peripheral surface of the first resin has a tapered diameter decreasing toward the proximal side, When the sixth condition is that the second condition is satisfied, and the outer diameter of the proximal end of the second radiopaque marker is larger than the outer diameter of a second proximal adjacent portion which is a portion of the second sheath adjacent to the proximal side of the formation region of the second radiopaque marker, a step portion between the proximal end of the second radiopaque marker and the second proximal adjacent portion is filled with a second resin, and the outer peripheral surface of the second resin tapers in diameter toward the proximal side, The stent delivery device according to claim 2 , which satisfies at least one of the fifth and sixth conditions.

5. the first radiopaque marker is formed in a tubular shape having a diameter larger than that of the first sheath; the first sheath has a first distal adjacent portion which is a portion of the first sheath adjacent to the distal side of a region where the first radiopaque marker is formed, and a first proximal adjacent portion which is a portion of the first sheath adjacent to the proximal side of a region where the first radiopaque marker is formed, and the seventh condition is that, when the radial dimension of a step between the first distal adjacent portion and the distal end of the first radiopaque marker is defined as a first step dimension and the radial dimension of a step between the proximal end of the first radiopaque marker and the first proximal adjacent portion is defined as a second step dimension, the second step dimension is equal to or less than 1 / 2 of the first step dimension; the second radiopaque marker is formed in a tubular shape having a diameter larger than that of the second sheath; the second sheath has a second distal adjacent portion which is a portion of the second sheath adjacent to the distal side of the region where the second radiopaque marker is formed, and a second proximal adjacent portion which is a portion of the second sheath adjacent to the proximal side of the region where the second radiopaque marker is formed, and the radial dimension of the step between the second distal adjacent portion and the distal end of the second radiopaque marker is defined as a third step dimension, and the radial dimension of the step between the proximal end of the second radiopaque marker and the second proximal adjacent portion is defined as a fourth step dimension, and the fourth step dimension is equal to or less than 1 / 2 of the second step dimension, The stent delivery device according to claim 1 , wherein at least one of the seventh condition and the eighth condition is satisfied.

6. The ninth condition is that the seventh condition is satisfied and the outer diameter of the proximal end of the first radiopaque marker tapers toward the proximal side. If the eighth condition is satisfied and the outer diameter of the proximal end of the second radiopaque marker tapers toward the proximal side, then the tenth condition is:

6. The stent delivery device according to claim 5, which satisfies at least one of the ninth and tenth conditions.

7. The eleventh condition is that the seventh condition is satisfied, the first radiopaque marker is composed of a plurality of first tubular portions connected in a distal-proximal direction, and the thickness of the distal first tubular portion, which is the first tubular portion located most distally among the plurality of first tubular portions, is greater than the thickness of the proximal first tubular portion, which is the first tubular portion located most proximal; If the eighth condition is satisfied, and the second radiopaque marker is configured with a plurality of second tubular portions connected in a distal-proximal direction, and the wall thickness of the distal second tubular portion, which is the second tubular portion located most distally among the plurality of second tubular portions, is greater than the wall thickness of the proximal second tubular portion, which is the second tubular portion located most proximal, then the twelfth condition is:

6. The stent delivery device according to claim 5, which satisfies at least one of the eleventh condition and the twelfth condition.

8. A stent delivery device as described in any one of claims 1 to 7, wherein the sheath branch portion is located proximal to the intermediate portions of the first radiopaque marker and the second radiopaque marker in the tip-to-base direction.

9. The first radiopaque marker is configured with a plurality of first tubular portions connected in a distal-proximal direction, a boundary between a proximal first tubular portion, which is the first tubular portion located at the most proximal side among the plurality of first tubular portions, and another first tubular portion adjacent to the proximal first tubular portion on the distal side thereof, is disposed at a position on the first sheath corresponding to the stent bifurcation portion, The second radiopaque marker is configured by a plurality of second tubular portions connected in the distal-proximal direction, 3. The stent delivery device according to claim 1, wherein the boundary between the proximal second tubular portion, which is the second tubular portion located most proximally among the plurality of second tubular portions, and the other second tubular portion adjacent to the proximal second tubular portion on the distal side thereof, is positioned at a position on the second sheath corresponding to the stent branch portion.

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