Stents

Abstract

To provide a stent which can be detained in an appropriate axial direction length with respect to a tube axial direction length of a lesioned part.SOLUTION: A stent 1 detained in an organic lumen includes a plurality of stent parts which are formed into cylindrical shapes from a wire material and are expandable / contractable in a radial direction almost orthogonal to the axial direction. The plurality of stent parts have a first stent part 11 detained first in an organic lumen and a second stent part 21 detained later. On one side part in the axial direction of the first stent part 11, an inside engaging part 35 engaging the second stent part 21 is provided. The inside engaging part 35 projects to the opposite side of an opening end 11a of one side part, and a force is given inside one side part from outside in the radial direction, so that it is formed so as to be displaced inside in the radial direction with respect to an inner peripheral surface of one side part.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a stent.

[0002] Conventionally, stents have been known that are placed at a lesion site, such as a narrowed or obstructed site, in a biological lumen, including a blood vessel, esophagus, bile duct, trachea, ureter, etc., to expand the diameter of the lesion site and maintain the patency of the biological lumen (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4651943 Summary of the Invention [Problem to be solved by the invention]

[0004] The stents described in Patent Document 1 and the like have a long, single structure in the axial direction. Therefore, in stent placement, a stent having an axial length close to the axial length of the lesion site in the biological lumen is selected and placed.

[0005] However, if a stent that is longer than necessary in the axial direction is placed relative to the axial length of the lesion, there will be an excess stent portion that does not directly function to treat the lesion, and this excess stent portion may interfere with the normal function of the body lumen or cause complications such as perforation. If the axial length of the stent is insufficient relative to the axial length of the lesion site, an additional stent must be placed.

[0006] Therefore, the present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a stent that can be placed with an axial length appropriate to the axial length of the lesion site. [Means for solving the problem]

[0007] One aspect of the present invention is a stent to be placed in a biological lumen, which is formed into a tubular shape from a wire and has a plurality of stent sections that are expandable and contractable in a radial direction that is approximately perpendicular to the axial direction. The plurality of stent sections include a first stent section that is placed in the biological lumen first and a second stent section that is placed later. One axial side of the first stent section is engaged with the second stent section. No. 1 An engagement portion is provided. No. 1 The engagement portion protrudes on the side opposite the open end of the one side portion and is configured so as to be displaced radially inward from the inner circumferential surface of the one side portion when a force is applied to the one side portion from the radially outside to the inside. A second engagement portion that engages with the first stent portion is provided on one axial side of the second stent portion. The second engagement portion protrudes from the side opposite the open end of the one side and is formed so as to be displaced radially outward from the outer circumferential surface of the one side when a force is applied to the one side from the radially inner side to the outer side. Effect of the Invention

[0009] According to the present invention, it is possible to provide a stent that can be placed with an axial length appropriate for the axial length of the lesion site. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 shows the elements of the stent of this embodiment in a separated state. [Diagram 2] FIG. 2 is a diagram showing an example of the configuration of a stent according to the present embodiment. [Diagram 3] 4 is an enlarged view showing a configuration example of the first and second main bodies. FIG. [Figure 4] FIG. 2 is a schematic diagram showing a longitudinal section of the stent in a region where the first stent section and the second stent section are overlapped. [Diagram 5] FIG. 2 is a diagram showing an example of a placement device used for placing a stent in this embodiment. [Figure 6] 1A to 1C are diagrams illustrating a procedure for placing a stent in a biological lumen. [Figure 7] FIG. 1(A) is a schematic diagram showing a longitudinal cross section of a first main body part placed in the digestive tract, and FIG. 1(B) is a schematic diagram showing a longitudinal cross section of a second main body part released from a sheath. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, examples of the configuration of a stent according to an embodiment of the present invention will be described with reference to the drawings. Here, the shapes, dimensions, etc. of each part in the drawings are shown diagrammatically and do not represent the actual shapes, dimensions, etc. In the drawings, the axial direction Ax of the member is indicated by an arrow as necessary. Also, the direction substantially perpendicular to the axial direction Ax is defined as the radial direction. In the drawings, one end side of the member is indicated by the symbol F as necessary, and the other end side opposite to the one end side is indicated by the symbol B as necessary.

[0012] Fig. 1 is a diagram showing the elements of the stent of this embodiment in a separated state, and Fig. 2 is a diagram showing an example of the configuration of the stent 1 of this embodiment. Although Fig. 1 and Fig. 2 show the stent 1 having a straight cylindrical shape, the shape of the stent 1 may be, for example, curved in an arch or twisted shape.

[0013] The stent 1 of this embodiment is applied to be placed in a lesion such as a narrowed or blocked site in a biological lumen such as a blood vessel, esophagus, bile duct, trachea, or ureter, and to expand the lesion. Fig. 6 described later shows an example in which the stent 1 is placed in a lesion 2a of the digestive tract 2 as an example of a biological lumen. The stent 1 is not limited to being placed in the digestive tract 2, and may be placed in other biological lumens.

[0014] 1, the stent 1 of this embodiment has a first stent section 11 arranged at one end and a second stent section 21 arranged at the other end. The first stent section 11 is placed in the digestive tract 2 first, and the second stent section 21 is placed in the digestive tract 2 after the first stent section 11.

[0015] When the stent 1 is placed, as shown in Fig. 2, the inner engagement portion 35 on the other end side of the first stent portion 11 and the outer engagement portion 36 on one end side of the second stent portion 21 are engaged with each other, and the first stent portion 11 and the second stent portion 21 are aligned in the axial direction in a state in which an area OA is generated where the opening edge portion 11b on the other end side of the first stent portion 11 and the opening edge portion 21b on one end side of the second stent portion 21 overlap each other. At this time, the opening edge portion 21b of the second stent portion 21 is disposed inside the opening edge portion 11b of the first stent portion 11. As a result, the first stent portion 11 and the second stent portion 21 are connected in the axial direction in the digestive tract 2 to form the stent 1.

[0016] The first stent portion 11 and the second stent portion 21 each have a main body portion that forms the framework of the stent 1. Hereinafter, the main body portion of the first stent portion 11 will also be referred to as the first main body portion 12, and the main body portion of the second stent portion 21 will also be referred to as the second main body portion 22. In addition, in describing parts common to the first main body portion 12 and the second main body portion 22, they may be collectively referred to as the first and second main body portions 12, 22.

[0017] The first and second main body portions 12, 22 are formed into a cylindrical shape having approximately the same diameter as the entire shape. In the first and second main body portions 12, 22, openings provided at both ends in the axial direction Ax communicate with each other, and a flow path through which objects flowing through the digestive tract 2 can pass when the stent 1 is placed in the digestive tract 2 is formed therein. In addition, the matter flowing through the digestive tract 2 may be in any state, including, for example, food immediately after ingestion that has not been digested at all, food that has been broken down as it passes through the digestive tract 2, and matter that has passed through the digestive tract 2 but has not been digested (for example, feces, etc.).

[0018] In addition, the first and second main body portions 12, 22 are expandable and contractable from a contracted state in which they contract radially inward to an expanded state in which they expand radially outward, and have a so-called self-expanding configuration in which the shape of the expanded state is memorized.

[0019] Here, the first stent section 11 and the second stent section 21 are housed in a sheath 41 of a placement device 40 described below and introduced into the digestive tract 2 in a state of being contracted radially inward. The first stent section 11 and the second stent section 21 are delivered to the lesion site 2a of the digestive tract 2 and then released from the sheath 41, where they expand radially outward. The stent section released from the placement device 40 may be expanded radially outward by expanding and pressing a balloon (not shown) from the inside.

[0020] FIG. 3 is an enlarged view showing an example of the configuration of the first and second main bodies 12 and 22. As shown in FIG. The first and second main body portions 12, 22 are formed into a cylindrical shape by combining first and second wires 31, 32 made of different materials. The first wire 31 is made of a material having a predetermined rigidity, such as a metal wire. The second wire 32 is made of a material having a relatively low rigidity compared to the first wire 31.

[0021] Examples of materials for the first wire 31 include known metals or metal alloys such as Ni-Ti alloy, stainless steel, titanium alloy, etc. Also, an alloy material having X-ray contrast may be used for the first wire 31, or a marker piece (not shown) made of an alloy material having X-ray contrast may be appropriately attached to the first wire 31. In these cases, the positions of the first stent portion 11 and the second stent portion 21 can be confirmed from outside the body.

[0022] Furthermore, the first wire rod 31 is not limited to a material formed into a wire shape as a material for forming the stent 1, and may be formed into a wire shape by laser cutting a thin-walled cylinder made of any of the above-mentioned metals, for example. That is, the first wire rod 31 may be any member having a portion formed into a wire shape in a state where the stent 1 is formed. Furthermore, the first wire 31 may have a cross section perpendicular to its axial direction that is circular, elliptical, rectangular, or the like. Furthermore, the first wire 31 may be made of a material other than metal (for example, ceramic, resin, etc.).

[0023] When a Ni-Ti alloy is used as the material for the first wire 31, the first and second main body portions 12, 22 can be adjusted to their expanded shape and then subjected to a predetermined heat treatment, thereby causing the first and second main body portions 12, 22 to memorize the expanded shape.

[0024] On the other hand, the second wire 32 is formed of a material that contains less metal or does not contain metal compared to the first wire 31. The second wire 32 is formed of a biocompatible resin string member, a thin metal wire, or the like.

[0025] When a resin string member is used as the second wire 32, materials such as fluororesin such as PTFE (polytetrafluoroethylene), polyester resin such as polyethylene terephthalate, nylon, etc. can be used. When a thin metal wire is used as the second wire 32, the wire may be made of a material having a lower rigidity than the first wire 31, or a wire made of the same material as the first wire 31 but having a smaller diameter than the first wire 31 may be used. In this embodiment, an example in which a resin string member is used as the second wire 32 will be described.

[0026] In addition, the second wire 32 may be, for example, long and circular, oval, rectangular, or the like in cross section perpendicular to the axial direction, or may be long and wide on one side perpendicular to the axial direction (belt-shaped or ribbon-shaped). The second wire 32 may contain a material having X-ray contrast properties. In this case as well, the positions of the first stent section 11 and the second stent section 21 can be confirmed from outside the body.

[0027] As shown in Fig. 3, the first and second main body portions 12, 22 each have a plurality of annular formation portions 33 arranged in the axial direction. Each annular formation portion 33 is formed in an annular shape by extending the first wire rod 31 in the circumferential direction. The first wire rod 31 in the annular formation portion 33 is bent in a zigzag shape in the axial direction so that peaks 31a and valleys 31b are alternately formed at a predetermined pitch. The annular formation portion 33 formed by the first wire rod 31 expands in diameter in the circumferential direction by its own expansion force, and serves to expand the diseased area 2a of the digestive tract 2 in which it is placed.

[0028] The adjacent annular forming portions 33 at one end and the other end in the axial direction are arranged such that the phases of the bent portions (peaks 31a) protruding at one end and the bent portions (valleys 31b) protruding at the other end are approximately overlapped in the axial direction. Each annular forming portion 33 has a bridge portion 34 that connects the first wire rod 31 between the annular forming portions 33 in order to transfer the first wire rod 31 to the adjacent annular forming portion 33 in the axial direction.

[0029] By providing the transition portion 34, it becomes possible to form a plurality of annular formation portions 33 arranged in the axial direction with a single first wire rod 31. The transition portion 34 may be formed by crimping a wire rod to the annular formation portion 33, or may be formed by laser cutting a thin-walled cylinder.

[0030] Further, the bridge portion 34 connecting the annular formation portions 33 is formed in a straight line, for example, connecting the peak portion 31a of the annular formation portion 33 and the valley portion 31b of the annular formation portion 33 adjacent in the axial direction.

[0031] In addition, the positions of the bridge portions 34 in the circumferential direction are shifted from each other in the multiple annular formation portions 33, and the positions of the bridge portions 34 in the circumferential direction do not overlap between adjacent annular formation portions 33. The positions of the bridge portions 34 in the circumferential direction may be shifted regularly in the axial direction or may be irregularly arranged. In this way, since the positions of the bridge portions 34 are shifted, it is difficult for the multiple bridge portions 34 to bend the first stent portion 11 or the second stent portion 21 to become difficult to bend. In other words, it is possible to suppress an increase in the axial force of the first stent portion 11 or the second stent portion 21 due to the presence of the bridge portions 34.

[0032] Furthermore, among the multiple annular formation parts 33, for example, two annular formation parts 33 that are not adjacent to each other in the axial direction are connected in the axial direction by the second wire rod 32. Therefore, the second wire rod 32 has the function of connecting the annular formation parts 33 in the axial direction while allowing the axial bending of the first and second main body parts 12, 22 and the circumferential displacement of the annular formation parts 33, and maintaining the overall shape of the first and second main body parts 12, 22 in a cylindrical shape. Furthermore, by combining the first wire rod 31 and the second wire rod 32, the amount of metal in the entire first and second main body parts 12, 22 is reduced, and the flexibility of the first stent part 11 and the second stent part 21 is increased. Of the multiple annular formation portions 33, the annular formation portions 33 connected by the second wire 32 may be disposed at positions adjacent to each other in the axial direction.

[0033] As shown in FIG. 3, the annular forming portions 33 are connected to the annular forming portions 33 separated by one annular forming portion 33 in the axial direction by the second wire rod 32, straddling the adjacent annular forming portions 33. These two annular forming portions 33 are connected by the second wire rod 32 at the peak portion 31a of one annular forming portion 33 and the valley portion 31b of the other annular forming portion 33. As a result, the second wire rod 32 is arranged in a ring shape in a pattern that is folded back in the axial direction between the two annular forming portions 33. In this manner, the first and second main body portions 12, 22 are formed by each annular forming portion 33 being connected to the annular forming portion 33 separated by one annular forming portion 33 in the axial direction by the second wire rod 32.

[0034] In addition, when the second wire 32 and the first wire 31 cross each other, a mesh is formed in the first and second main body portions 12, 22, and this mesh also suppresses in-growth, which is the infiltration of biological tissue from the digestive tract 2 into the stent 1.

[0035] Fig. 4 is a schematic diagram showing a longitudinal section of the stent 1 in an area OA where the first stent section 11 and the second stent section 21 are overlapped. For simplicity, Fig. 4 shows only the first wires 31 of the first and second main body sections 12, 22, and does not show the second wires 32.

[0036] In region OA of the stent 1, the first stent section 11, which is placed first, is located on the outer periphery side, and the second stent section 21, which is placed later, is located on the inner periphery side. The annular formation portions 33 of the second stent section 21 enter between and engage with the annular formation portions 33 of the first stent section 11, whereby the first stent section 11 and the second stent section 21 engage with each other. Specifically, an inner engagement portion 35 that engages with the second stent portion 21 is provided at the opening edge portion 11b (one side portion in the axial direction) on the other end side of the first stent portion 11. The inner engagement portion 35 is formed, for example, by a bent portion (ridge portion 31a) protruding on the opposite side (one end side) to the opening end 11a of the annular formation portion 33. The inner engagement portion 35 is formed so as to be displaced radially inward from the inner circumferential surface S1 of the first main body portion 12 when a force is applied from the radial outside to the inside to the opening edge portion 11b by, for example, a diseased site 2a of the digestive tract 2 in which the first stent portion 11 is placed. An outer engagement portion 36 that engages with the first stent portion 11 is provided at the opening edge portion 21b (one side portion in the axial direction) on one end side of the second stent portion 21. The outer engagement portion 36 is formed, for example, by a bent portion (valley portion 31b) protruding on the opposite side (other end side) to the opening end 21a of the annular formation portion 33. The outer engagement portion 36 is formed, for example, so as to be displaced radially outward from the outer circumferential surface S2 of the second main body portion 22 by a force that expands from the radial inside to the radial outside and is applied to the opening edge portion 21b when the second stent portion 21 is released from the sheath 41.

[0037] Returning to Fig. 1, a first flare portion 13 that widens in diameter toward the one end is formed at one end of the first main body portion 12. Also, a second flare portion 23 that widens in diameter toward the other end is formed at the other end of the second main body portion 22. The first flare portion 13 and the second flare portion 23 are both formed, for example, by braiding wires, and have the function of suppressing displacement (migration) of the stent 1 by generating friction between the stent 1 and the inner wall of the digestive tract 2 when the stent 1 is placed.

[0038] Although the first and second flared portions 13, 23 are illustrated as an example of a mechanism for suppressing displacement (migration) of the stent 1, this is merely an example and is not intended to be limiting. For example, instead of the first and second flared portions 13, 23, barbs that pierce the inner wall of the digestive tract 2 may be provided.

[0039] FIG. 5 is a diagram showing an example of an indwelling device 40 used when placing the first stent section 11 and the second stent section 21 at a lesion site. The placement device 40 includes a sheath 41 and an axial member 42 that is disposed inside the sheath 41 and is capable of anchoring the first stent section 11 and the second stent section 21 .

[0040] The sheath 41 is a long tubular member and is made of a flexible material such as a biocompatible synthetic resin. The sheath 41 can accommodate the first stent portion 11 and the second stent portion 21 in a contracted state.

[0041] The shaft-shaped member 42 is an elongated member configured to be movable forward and backward along the axial direction Ax of the sheath 41 inside the sheath 41. For example, the shaft-shaped member 42 has an outer shaft portion 42a and an inner shaft portion 42b inserted into the outer shaft portion 42a.

[0042] The outer shaft portion 42a is a long tubular member having a substantially constant outer diameter. A second locked portion 44 to which the second stent portion 21 is locked is provided on the distal end side of the outer shaft portion 42a. The inner shaft portion 42b is coaxially inserted into the outer shaft portion 42a so that their axes are substantially aligned, and one end portion of the inner shaft portion 42b is exposed from the outer shaft portion 42a. A distal tip 45 that closes an opening on one end side of the sheath 41 is attached to one end of the inner shaft portion 42b. A first locked portion 43 to which the first stent portion 11 is locked is provided on the inner shaft portion 42b slightly toward the other end side from the distal tip 45.

[0043] Next, a procedure for placing the stent 1 of this embodiment in the lesion site 2a of the digestive tract 2 will be described with reference to Fig. 6. In the example of Fig. 6, a case will be described in which one end side is the anus side and the other end side is the mouth side.

[0044] First, as shown in FIG. 6(A), the placement device 40 is placed in the digestive tract 2 so as to pass through the lesion site 2a of the digestive tract 2.

[0045] Next, in the placement device 40, the sheath 41 is displaced toward the other end with the position of the axial member 42 fixed. Then, the first stent section 11 engaged with the inner shaft section 42b is released from the inside of the sheath 41 into the digestive tract 2. At this time, the second stent section 21 engaged with the outer shaft section 42a is restricted from moving in the axial direction Ax relative to the sheath 41, and the second stent section 21 moves integrally with the sheath 41 toward the other end in the axial direction Ax.

[0046] The first stent portion 11 self-expands radially outward when released from the sheath 41, and is placed in close contact with the inner wall surface of the lesion site 2a of the digestive tract 2, as shown in FIG. 6(B).

[0047] Fig. 7(A) is a schematic diagram showing a longitudinal section along the axial direction of the first main body portion 12 placed in the digestive tract 2. For simplicity, Fig. 7(A) shows only the first wire 31 (annular formation portion 33) of the first main body portion 12, and omits the illustration of the second wire 32.

[0048] The first body portion 12 presses the lesion site 2a of the digestive tract 2 radially outward by its self-expansion force. Meanwhile, the first body portion 12 is pushed back radially inward by a reaction force from the lesion site 2a of the digestive tract 2. As a result, the portion of the first body portion 12 facing the lesion site 2a is bent radially inward by the application of force from the radially outward. At this time, the second wire material 32 having low rigidity bends flexibly, whereas the first wire material 31 having high rigidity is less likely to deform and is displaced so as to protrude radially inward from the inner circumferential surface S1 on the other end side.

[0049] Therefore, in the portion of the first body portion 12 facing the diseased site 2a, the inner engagement portion 35 on one end side of the annular formation portion 33 is displaced so as to protrude radially inward from the inner circumferential surface S1 of the first body portion 12 (FIG. 7(A)). Note that the second wire 32 of the first body portion 12 connects the annular formation portion 33 in the axial direction without impeding the above-mentioned displacement of the inner engagement portion 35 (annular formation portion 33) in the first body portion 12, and also functions to assist the above-mentioned displacement.

[0050] After the first stent section 11 is placed, the position is confirmed using an endoscope or X-ray, and the second stent section 21 is released so as to overlap the first stent section 11 from the inside, as shown in Figure 6 (C).

[0051] Specifically, after the first stent portion 11 is released, the restriction on the movement of the second stent portion 21 engaged with the outer shaft portion 42a in the axial direction Ax relative to the sheath 41 is released. Then, the second stent portion 21 is aligned with a desired position, and the position of the shaft-shaped member 42 is fixed. In this state, when the sheath 41 is displaced toward the other end along the axial direction Ax, the second stent portion 21 engaged with the second engaged portion 44 of the outer shaft portion 42a is released from inside the sheath 41 into the digestive tract 2.

[0052] Fig. 7(B) is a diagram showing a schematic longitudinal section along the axial direction of the second main body portion 22 released from the sheath 41. For simplicity, Fig. 7(B) shows only the first wire 31 (annular forming portion 33) of the second main body portion 22, and omits the illustration of the second wire 32.

[0053] When the second main body portion 22 in the contracted state is released from the sheath 41, a force is applied in the radially outward direction due to the self-expansion force, and the second main body portion 22 is displaced so as to expand radially outward. At this time, the second wire material 32 having low rigidity bends flexibly, whereas the first wire material 31 having high rigidity is difficult to deform, and is displaced so as to protrude radially outward beyond the outer circumferential surface S2 on the one end side.

[0054] Therefore, in the second body portion 22, the outer engaging portion 36 on the other end side of the annular forming portion 33 is displaced so as to protrude radially outward from the outer circumferential surface S2 of the second body portion 22 (FIG. 7(B)). Note that the second wire 32 of the second body portion 22 also functions to axially connect the annular forming portion 33 without impeding the above-mentioned displacement of the outer engaging portion 36 (annular forming portion 33) in the second body portion 22, and to assist the above-mentioned displacement.

[0055] When the second stent section 21 is expanded on the inner periphery side of the first stent section 11, the first stent section 11 placed in the digestive tract 2 is urged from the inside toward the outside in the radial direction by the expansion force of the second stent section 21. At this time, the annular forming section 33 made of the first wire rod 31 of the outer engagement section 36 enters between the annular forming section 33 made of the first wire rod 31 of the inner engagement section 35 and engages with it, so that the first stent section 11 and the second stent section 21 are engaged with each other (FIG. 4). The second wire rod 32 in the first and second main body sections 12, 22 has a lower rigidity than the first wire rod 31 and bends flexibly when it comes into contact with the first wire rod 31. Therefore, the second wire rod 32 does not hinder the engagement between the first stent section 11 and the second stent section 21.

[0056] Fig. 6(D) shows a state where the release of the second stent section 21 has been completed and the placement of the stent 1 has been completed. In the stent 1 in Fig. 6(D), the first stent section 11 and the second stent section 21 are engaged with each other, thereby restricting the relative displacement of the first stent section 11 and the second stent section 21 in the axial direction.

[0057] Furthermore, when the stent 1 is placed, an area OA is generated where the first stent section 11 and the second stent section 21 overlap. In the area OA, the expansion force of the stent 1 is amplified by the action of the expansion forces of both the first stent section 11 and the second stent section 21. This makes it possible to expand the lesion site 2a more reliably in the area OA.

[0058] In the region OA, the mesh of the skeleton is shifted in the axial and circumferential directions, so that the mesh of the skeleton is finer than in the region where the first stent portion 11 and the second stent portion 21 do not overlap. This makes it easier to suppress the phenomenon of infiltration (ingrowth) of cellular tissue at the lesion site into the stent 1.

[0059] In this embodiment, the overall length of the stent 1 placed in the lesion site 2a can be changed by adjusting the axial position of the second stent portion 21 relative to the first stent portion 11. Furthermore, by preparing multiple types of products with different axial lengths for either the first stent portion 11 or the second stent portion 21 and changing the combination of the stent portions to be placed according to the lesion site 2a, it becomes easy to appropriately control the overall length of the stent 1.

[0060] The effects of the stent 1 of this embodiment will be described below. In this embodiment, the stent 1 placed in the digestive tract 2 (biological lumen) is formed from a wire into a tubular shape, and has a first stent section 11 placed first in the digestive tract 2 and a second stent section 21 placed later, as multiple stent sections that can expand and contract in a radial direction substantially perpendicular to the axial direction. An inner engagement section 35 that engages with the second stent section 21 is provided on the other axial end side (one side portion) of the first stent section 11. The inner engagement section 35 protrudes on the side opposite to the open end 11a on the other end side, and is formed so as to be displaced radially inward from the inner circumferential surface S1 on the other end side when a force is applied to the other end side from the radial outside to the inside. For example, when the first stent section 11 is placed in the lesion 2a of the digestive tract 2, the inner engagement section 35 of the first stent section 11 is displaced radially inward from the inner circumferential surface S1 on the other end side, and is easily engaged with the second stent section 21 placed inside the first stent section 11. The inner engagement section 35 engages with the second stent section 21 to form the stent 1, and the overall length of the stent 1 placed in the lesion can be changed by adjusting the overlapping width of the stent sections and changing the combination of the stent sections. In addition, the engagement of the inner engagement section 35 restricts the relative axial displacement between the first stent section 11 and the second stent section 21, so that the overall length of the stent 1 consisting of a plurality of stent sections is maintained. Therefore, the stent 1 of this embodiment can be placed with an appropriate axial length relative to the tubular axial length of the lesion. In other words, in this embodiment, the portion of the stent 1 that extends beyond the diseased area and is placed in a healthy area can be reduced, thereby reducing the possibility of damaging the healthy area.

[0061] The first stent section 11 of this embodiment is formed into a cylindrical shape by combining first and second wires 31, 32 made of different materials. The inner engagement section 35 is formed from the wire having the relatively higher rigidity among the first and second wires 31, 32. The second wire 32 is connected to the first wire 31 forming the inner engagement section 35 so as to assist the inner engagement section 35 in displacing radially inward from the inner circumferential surface S1. As a result, when a force is applied to the first stent section 11 from the radial outside, the inner engagement section 35 formed of the highly rigid first wire rod 31 can be displaced so as to protrude radially inward beyond the inner circumferential surface S1 on the other end side. Here, the second wire rod 32 has a relatively lower rigidity than the first wire rod 31 forming the inner engagement section 35, and has a higher degree of freedom of movement, so that the displacement of the inner engagement section 35 is not hindered by the second wire rod 32, and the inner engagement section 35 can be appropriately displaced.

[0062] In this embodiment, an outer engagement portion 36 that engages with the first stent portion 11 is provided on one axial end side (one side portion) of the second stent portion 21. The outer engagement portion 36 protrudes to the side opposite the open end 21a on the one end side, and is formed so as to be displaced radially outward from the outer circumferential surface S2 on the one end side when a force is applied to the one end side from the radially inner side to the outer side. For example, when the second stent section 11 is released from the sheath 41, the outer engagement section 36 of the second stent section 21 is displaced radially outward from the outer circumferential surface S2 on one end side, and becomes more likely to engage with the first stent section 11 disposed outside the second stent section 21. Also, by forming the stent 1 by engaging the outer engagement section 36 with the first stent section 11, it is possible to obtain the same effect as in the case of the inner engagement section 35. Moreover, by engaging the first stent section 11 having the inner engagement section 35 with the second stent section 21 having the outer engagement section 36, the relative displacement in the axial direction between the first stent section 11 and the second stent section 21 can be more reliably restricted.

[0063] The second stent section 21 of this embodiment is formed into a cylindrical shape by combining first and second wires 31, 32 made of different materials. The outer engagement section 36 is formed from the wire having the relatively higher rigidity among the first and second wires 31, 32. The second wire 32 is connected to the first wire 31 forming the outer engagement section 36 so as to assist the displacement of the outer engagement section 36 radially outward from the outer circumferential surface S2. As a result, when a force is applied to the second stent section 21 from the radial inside, the outer engagement section 36 formed of the highly rigid first wire rod 31 can be displaced so as to protrude radially outward beyond the outer circumferential surface S2 on one end side. Here, the second wire rod 32 has a relatively lower rigidity than the first wire rod 31 forming the outer engagement section 36, and has a higher degree of freedom of movement, so that the second wire rod 32 does not hinder the displacement of the outer engagement section 36, and the inner engagement section 36 can be appropriately displaced.

[0064] The present invention is not limited to the above-described embodiment, and various improvements and design changes may be made without departing from the spirit of the present invention.

[0065] For example, in the above embodiment, the first stent section 11 is provided with the inner engagement portion 35, and the second stent section 21 is provided with the outer engagement portion 36, but this is merely an example and is not intended to be limiting. The second stent section 21 does not necessarily have to be provided with the outer engagement portion 36, and the first stent section 11 does not necessarily have to be provided with the inner engagement portion 35.

[0066] In the above embodiment, the first and second body portions 12, 22 are configured by combining the first and second wire rods 31, 32 made of different materials. However, in the present invention, either one of the first and second body portions 12, 22 may be configured only of the first wire rod 31.

[0067] In the above embodiment, the first stent section 11 is placed first on the anal side, and the second stent section 21 is placed later on the oral side. However, in the present invention, the first stent section 11 may be placed first on the oral side, and the second stent section 21 may be placed later on the anal side.

[0068] In the above embodiment, the transition portion 34 is formed in a straight line, but the shape of the transition portion 34 is merely an example and is not limited thereto, and may be changed as appropriate. For example, although not shown in the drawings, the transition portion 34 may be formed in an S-shape in which a bent portion protruding from one end side is continuous with a bent portion protruding from the other end side. In this case, the curved portion protruding on the opposite side of the opening edge 11a of the annular formation portion 33 in the crossover portion 34 of the first stent portion 11 can function in the same manner as the inner engagement portion 35, and the curved portion protruding on the opposite side of the opening edge 21a of the annular formation portion 33 in the crossover portion 34 of the second stent portion 21 can function in the same manner as the outer engagement portion 36. Furthermore, by arranging the transition portion 34 so that each bend in the transition portion 34 substantially overlaps with the peaks 31a and valleys 31b of the annular formation portion 33, interference between the transition portion 34 and the annular formation portion 33 is suppressed.

[0069] Furthermore, the annular formation portions 33 in the first and second main body portions 12, 22 do not necessarily need to be connected in an annular shape as long as the first wire rod 31 goes around in the circumferential direction. For example, the first wire rod 31 bent in a zigzag shape may be spirally wound to form a plurality of annular formation portions 33, and the bent portions of these annular formation portions 33 may be connected in the axial direction by the second wire rod 32. In other words, the first and second main body portions 12, 22 do not necessarily need to include the jumper portion 34, and whether or not the jumper portion 34 is included can be changed as appropriate.

[0070] In addition, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0071] REFERENCE SIGNS LIST 1... stent, 2... digestive tract (biological lumen), 2a... lesion site, 11... first stent portion, 11a... opening edge portion, 12... first main body portion, 21... second stent portion, 21a... opening edge portion, 22... second main body portion, 31... first wire rod, 32... second wire rod, 33... annular formation portion, 35... inner engagement portion, 36... outer engagement portion, 40... placement device, 41... sheath

Claims

1. A stent to be placed in a biological lumen, The stent is formed into a tubular shape from a wire rod and is expandable and contractable in a radial direction substantially perpendicular to the axial direction. the plurality of stent sections include a first stent section that is placed first in the biological lumen and a second stent section that is placed later; a first engagement portion that engages with the second stent portion is provided on one axial side of the first stent portion; The first engagement portion protrudes on an opposite side to an open end of the one side portion, and is formed so as to be displaced radially inward relative to an inner circumferential surface of the one side portion when a force is applied to the one side portion from a radially outer side to an inner side, a second engagement portion that engages with the first stent portion is provided on one axial side of the second stent portion; The second engagement portion protrudes from a side opposite to an open end of the one side portion, and is formed so as to be displaced radially outward from an outer circumferential surface of the one side portion when a force is applied from a radially inner side to an outer side of the one side portion. Stent.

2. The first stent portion is formed into a cylindrical shape by combining first and second wires made of different materials, The first engagement portion is formed from one of the first and second wire rods that has a relatively high rigidity.

2. The stent of claim 1.

3. The second wire is connected to the first wire forming the first engagement portion so as to assist the first engagement portion in displacing radially inward from the inner circumferential surface of the first engagement portion. The stent of claim 2.

4. The second stent portion is formed into a cylindrical shape by combining first and second wires made of different materials, The second engagement portion is formed from one of the first and second wire rods that has a relatively high rigidity.

2. The stent of claim 1.

5. The second wire is connected to the first wire forming the second engagement portion so as to assist the second engagement portion in displacing radially outward beyond the outer circumferential surface of the second engagement portion.

5. The stent of claim 4.

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