Stent

Abstract

To provide a stent capable of maintaining an open state of a biological lumen while suppressing a decrease in a normal function of the biological lumen.SOLUTION: A stent 1 placed in a biological lumen 2 is formed in a cylindrical shape by combining first and second wires 11, 12 having materials different from each other. The first wire 11 has predetermined rigidity. The second wire 12 has relatively lower rigidity than that of the first wire 11.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

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

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-44292 Summary of the Invention [Problem to be solved by the invention]

[0004] The stents described in Patent Document 1 and elsewhere have a structure in which one or more metal wires are woven together. In particular, in uncovered stents that do not have a coating, the wires are woven at a high density to prevent the lumen of the stent from being blocked by infiltration of biological tissue. However, if the metal density of the stent is high, there is a risk that the normal function of the biological lumen will be impaired due to excessive pressure or damage to normal areas caused by reduced flexibility.

[0005] Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a stent that can maintain the patency of a biological lumen while suppressing a decline in the normal function of the biological lumen. [Means for solving the problem]

[0006] One aspect of the present invention is a stent to be placed in a biological lumen, which is formed into a tubular shape by combining first and second wire rods made of different materials, where the first wire rod has a predetermined rigidity and the second wire rod has a relatively lower rigidity than the first wire rod. [Effects of the Invention]

[0007] According to the present invention, a stent can be provided that can maintain the patency of a biological lumen while suppressing a decline in the normal function of the biological lumen. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a front view showing a configuration example of a stent according to a first embodiment. [Figure 2] FIG. 1 is a perspective view showing a configuration example of a stent according to a first embodiment. [Figure 3] FIG. 2 is a partially enlarged view of FIG. [Figure 4] FIG. 1 is a schematic diagram showing an example of a stent placement site. [Figure 5] FIG. 1 is a diagram schematically illustrating a state in which a stent is placed in a biological lumen. [Figure 6] FIG. 4 is a diagram showing a modification of FIG. 3. [Figure 7] FIG. 10 is a diagram showing a configuration example of a stent according to a second embodiment. [Figure 8] 10A and 10B are diagrams illustrating examples of knots of a second wire rod in the second embodiment. [Figure 9] FIG. 10 is a diagram showing a configuration example of a stent according to a third embodiment. [Figure 10] 13A and 13B are diagrams showing another example of the second holding portion of the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] 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 schematically 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 needed. Also, the direction approximately 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 needed, and the other end side opposite to the one end side is indicated by the symbol B as needed.

[0010] (First embodiment) Fig. 1 is a front view showing an example of the configuration of a stent 1 of a first embodiment. Fig. 2 is a perspective view showing an example of the configuration of a stent 1 of a first embodiment. Fig. 3 is a partially enlarged view of Fig. 1. Fig. 4 is a schematic view showing an example of an implantation site of the stent 1. Fig. 5 is a diagram schematically showing a state in which the stent 1 is implanted in a biological lumen.

[0011] The stent 1 of the first embodiment is placed in a lesion such as a narrowed or obstructed area in a biological lumen such as a blood vessel, esophagus, bile duct, trachea, or ureter, and is used to expand the lesion. Figures 4 and 5 show a case where the stent 1 is placed in a lesion 2a in the digestive tract 2 (for example, the duodenum) as an example of a biological lumen. Note that the stent 1 is not limited to being placed in the digestive tract 2, and may be placed in other biological lumens.

[0012] 1 and 2, the stent 1 is formed in a cylindrical shape with one end and the other end communicating in the axial direction Ax. As shown in Fig. 5, when the stent 1 is placed, the outer peripheral surface of the stent 1 presses the inner surface of the placement site (lesion site 2a in the digestive tract 2) radially outward, and the lesion site 2a, which has narrowed inward to occlude the digestive tract 2, is pushed radially outward.

[0013] 1 and 2 show the stent 1 having a straight cylindrical shape, but the shape of the stent 1 may be, for example, an arched curved shape or a twisted shape. Furthermore, the end of the stent 1 may be formed with a flared portion (not shown) whose diameter increases toward the end. The specifications of the stent 1, such as the dimensions, are set appropriately depending on, for example, the diameter of the digestive tract 2 in which the stent 1 is to be placed, the length of the area in which the stent 1 is to be placed, and the like.

[0014] The stent 1 has a so-called self-expanding configuration in which the expanded shape is memorized, and is expandable and contractible from a contracted state in which it contracts radially inward to an expanded state in which it expands radially outward. The stent 1 of the first embodiment is introduced into the digestive tract 2 in a state (not shown) in which it is contracted radially inward using a catheter (not shown). After being delivered to the lesion site 2a in the digestive tract 2, the stent 1 is released from the sheath of the catheter and expands radially outward. The stent 1 released from the catheter may be expanded radially outward by expanding and pressing a balloon (not shown) from inside the stent 1.

[0015] The lumen of the stent 1 forms a flow path through which fluid flowing through the digestive tract 2 can pass from one end to the other end in the axial direction Ax, for example, when the stent 1 is placed in the digestive tract 2 with one end facing the upstream side (mouth side) of the digestive tract 2. The fluid flowing through the digestive tract 2 may be in any state, including, for example, food immediately after ingestion that has not undergone any digestion, food that has been broken down as it passes through the digestive tract 2, and food that has not been digested even after passing through the digestive tract 2 (for example, feces).

[0016] The stent 1 is formed into a cylindrical shape by combining first and second wire rods 11 and 12 made of different materials. The first wire rod 11 is made of a material having a predetermined rigidity, such as a metal wire. The second wire rod 12 is made of a material having a relatively lower rigidity than the first wire rod 11.

[0017] Examples of materials for the first wire 11 include known metals or metal alloys such as Ni-Ti alloys, stainless steel, and titanium alloys. The first wire 11 may be made of an alloy material that is radiopaque, or a marker piece (not shown) made of an alloy material that is radiopaque may be attached to the first wire 11. In these cases, the position of the stent 1 can be confirmed from outside the body.

[0018] Furthermore, the first wire rod 11 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, for example, a thin-walled cylindrical body made of any of the above-mentioned metals. In other words, the first wire rod 11 may be any member having a portion formed into a wire shape when the stent 1 is formed. Furthermore, the cross section of the first wire 11 perpendicular to its axial direction may be circular, oval, rectangular, or the like. Furthermore, the first wire 11 may be made of a material other than metal (for example, ceramic, resin, etc.).

[0019] When a Ni—Ti alloy is used as the material for the first wire 11, the stent 1 can be made to memorize the expanded shape by performing a predetermined heat treatment after adjusting the stent 1 to the expanded shape.

[0020] On the other hand, the second wire 12 has a relatively low metal content or is made of a material that does not contain metal compared to the first wire 11. The second wire 12 is made of a biocompatible resin string member or a thin metal wire.

[0021] When a resin string member is used as the second wire 12, 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 12, the wire may be made of a material having lower rigidity than the first wire 11, or may be made of the same material as the first wire 11 but with a smaller diameter than the first wire 11. In the first embodiment, an example in which a resin string member is used as the second wire 12 will be described.

[0022] Furthermore, the second wire 12 may be, for example, a long wire having a cross section perpendicular to the axial direction that is circular, oval, rectangular, etc., or may be a long wire having a wide side perpendicular to the axial direction (strip-shaped or ribbon-shaped). The second wire 12 may also contain a material that is radiopaque. In this case, too, the position of the stent 1 can be confirmed from outside the body. Furthermore, to prevent the stent 1 from shifting position relative to the digestive tract 2, the second wire 12 may be provided with a locking pin (such as a barb) that hooks onto the inner wall of the digestive tract 2, although this is not shown.

[0023] As shown in Figures 1 to 3, the stent 1 has a plurality of annular formation portions 13 arranged in the axial direction. Each annular formation portion 13 is formed into a ring shape by extending a first wire rod 11 along the circumferential direction of the stent 1. The first wire rod 11 in the annular formation portion 13 is bent in a zigzag pattern in the axial direction so that peaks 11a and valleys 11b are formed alternately at a predetermined pitch. The annular formation portion 13 formed by the first wire rod 11 expands in diameter in the circumferential direction by its own expansion force, and serves to dilate the lesion site 2a of the digestive tract 2 in which it is placed.

[0024] The annular forming portions 13 adjacent to each other at one end and the other end in the axial direction are arranged such that the positions of the bent portions (peak portions 11a) protruding toward one end and the bent portions (valley portions 11b) protruding toward the other end are approximately overlapped in the axial direction. Each annular forming portion 13 has a bridge portion 14 that connects the first wire rod 11 between the annular forming portions 13 to transfer the first wire rod 11 to the annular forming portion 13 adjacent to each other in the axial direction.

[0025] By providing the transition portion 14, it becomes possible to form a plurality of annular forming portions 13 arranged in the axial direction using a single first wire rod 11. The transition portion 14 may be formed by crimping a wire rod to the annular forming portion 13, or may be formed by laser cutting a thin-walled cylinder.

[0026] Furthermore, the bridge portion 14 connecting the annular formation portions 13 is formed linearly, for example, connecting the peak portion 11a of the annular formation portion 13 and the valley portion 11b of the annular formation portion 13 adjacent in the axial direction. The transition portion 14 may be formed in an S-shape, with a bent portion protruding from one end and a bent portion protruding from the other end being continuous (see FIG. 6). In this case, the transition portion 14 is arranged so that each bent portion of the transition portion 14 substantially overlaps with the peaks 11a and valleys 11b of the annular forming portion 13. This prevents interference between the transition portion 14 and the annular forming portion 13.

[0027] Furthermore, the positions of the crossover portions 14 in the circumferential direction of the multiple annular formation portions 13 are offset from one another, and the crossover portions 14 of adjacent annular formation portions 13 do not overlap in the circumferential direction. The crossover portions 14 may be regularly or irregularly offset from one another in the axial direction. In this way, the crossover portions 14 are offset from one another, which reduces the likelihood of the multiple crossover portions 14 being stretched and making it difficult for the stent 1 to bend. In other words, the presence of the crossover portions 14 can prevent the axial force of the stent 1 from increasing.

[0028] Furthermore, among the multiple annular formation portions 13, for example, two annular formation portions 13 that are not adjacent in the axial direction are connected in the axial direction by the second wire rod 12. Therefore, the second wire rod 12 functions to connect the annular formation portions 13 in the axial direction while allowing for axial bending of the stent 1 and circumferential displacement of the annular formation portions 13, thereby maintaining the overall cylindrical shape of the stent 1. Furthermore, by combining the first wire rod 11 and the second wire rod 12, the amount of metal in the entire stent 1 is reduced, and the flexibility of the stent 1 is increased. Of the multiple annular formation portions 13, the annular formation portions 13 connected by the second wire rod 12 may be disposed at positions adjacent to each other in the axial direction.

[0029] As shown in Figures 1 to 3, the annular formation portions 13 are connected to the annular formation portions 13 that are separated by one annular formation portion 13 in the axial direction by the second wire rod 12, spanning adjacent annular formation portions 13. These two annular formation portions 13 are connected by the second wire rod 12 at the peak portion 11a of one annular formation portion 13 and the valley portion 11b of the other annular formation portion 13. As a result, the second wire rod 12 is arranged in a ring shape in a pattern that is folded back in the axial direction between the two annular formation portions 13. In this way, the stent 1 is formed by connecting each annular formation portion 13 to the annular formation portion 13 that is separated by one annular formation portion 13 in the axial direction by the second wire rod 12.

[0030] Furthermore, the crossing of the second wires 12 and the first wires 11 forms a mesh in the stent 1, which also inhibits in-growth of biological tissue from the digestive tract 2 into the stent 1.

[0031] The effects of the stent 1 of the first embodiment will be described below. In the first embodiment, the stent 1 to be placed in the digestive tract 2 (biological lumen) is formed into a cylindrical shape by combining first and second wire rods 11 and 12 made of different materials. The first wire rod 11 has a predetermined rigidity, and the second wire rod 12 has a relatively lower rigidity than the first wire rod 11. The stent 1 of the first embodiment is capable of maintaining an open state of the digestive tract 2 by arranging the first wires 11 having a predetermined rigidity in a tubular shape. Furthermore, the stent 1 of the first embodiment uses second wires 12 having a rigidity relatively lower than that of the first wires 11, thereby making it possible to relatively reduce the rigidity of the entire stent 1 while maintaining the fineness of the mesh of the stent 1. This increases the flexibility of the stent 1, thereby preventing the stent 1 from excessively compressing normal parts of the digestive tract 2 and causing damage to the digestive tract 2, and thereby preventing a decline in the normal function of the digestive tract 2.

[0032] According to the first embodiment, the first wire 11 is made of a material containing metal, and the second wire 12 is made of a material that has a relatively lower metal content than the first wire 11 or does not contain metal. With the above configuration, the amount of metal in the entire stent 1 can be reduced, and the flexibility of the stent 1 can be increased.

[0033] The stent 1 of the first embodiment has a plurality of annular formations 13 formed by extending a first wire rod 11 in the circumferential direction of the stent 1. The plurality of annular formations 13 are arranged side by side in the axial direction of the stent 1 and are connected in the axial direction by a second wire rod 12. By connecting the plurality of annular formations 13 formed by the first wire rod 11 in the axial direction by the second wire rod 12, which has a relatively low rigidity, the axial flexibility of the stent 1 can be ensured. This makes it easier to place the stent 1 in a curved digestive tract 2 and also makes it less likely that kinking will occur due to bending of the stent 1.

[0034] The annular formation portion 13 has peaks 11a and valleys 11b (bent portions) formed by bending the first wire rod 11 in the axial direction, and the peaks 11a and valleys 11b of the multiple annular formation portions 13 are connected by the second wire rod 12. Furthermore, of the multiple annular formation portions 13, the peaks 11a and valleys 11b of any two annular formation portions 13 that are not adjacent to each other in the axial direction are connected by the second wire rod 12. With the above configuration, the second wire rod 12 crosses the first wire rod 11 to form a mesh, which can suppress in-growth into the stent 1.

[0035] (Second embodiment) 7 is a diagram showing a configuration example of a stent 1a of the second embodiment. In the following description of each embodiment, elements common to the first embodiment are given the same reference numerals and redundant description will be omitted.

[0036] Similar to the stent 1 of the first embodiment, the stent 1a of the second embodiment is formed into a cylindrical shape by combining a first wire rod 11 and a second wire rod 12, and has a plurality of annular formation portions 13 formed from the first wire rod 11 in the axial direction. The annular formation portions 13 are connected to an annular formation portion 13 separated by one annular formation portion 13 in the axial direction by a second wire rod 12, straddling adjacent annular formation portions 13. These two annular formation portions 13 are connected by the second wire rod 12 at the peak portion 11a of one annular formation portion 13 and the valley portion 11b of the other annular formation portion 13. The material of the second wire rod 12 in the second embodiment is not particularly limited as long as it has low rigidity and is biocompatible enough to form a first retention portion 15 (described later).

[0037] In the second embodiment, the second wire 12 is bound to and held by the first holding portion 15 formed on the peak portion 11a or the valley portion 11b of the annular forming portion 13, respectively.

[0038] FIG. 8 shows an example of the first holding portion 15 of the second wire rod 12 in the second embodiment. The first holding portion 15 has a wound portion 15a in which the second wire rod 12 is wound around the held portion (peak portion 11a or valley portion 11b) of the first wire rod 11 in a tight and tight state for two or more turns. FIG. 8 shows an example in which the second wire rod 12 is wound around the held portion for two turns. The wound portion 15a of the first holding portion 15 is bundled by passing the second wire rod 12 through it, and the bundled wound portion 15a is fixed with a one-sided knot 15b. Note that the way of tying the knot 15b is not limited to a one-sided knot as long as it can fix the wound portion 15a.

[0039] In the wound portion 15a of the first holding portion 15, the second wire rod 12 is in close contact with the held portion of the first wire rod 11 in the circumferential direction over a length at least twice the circumferential length of the first wire rod 11. Therefore, sufficient friction is generated between the second wire rod 12 of the first holding portion 15 and the held portion, making it difficult for the first holding portion 15 to shift position relative to the held portion.

[0040] Furthermore, the second wire rod 12 of the winding portion 15a is bundled and fixed with a knot 15b. Therefore, even if an external force acts on the second wire rod 12, the second wire rod 12 of the winding portion 15a maintains a state of close contact with the held portion of the first wire rod 11. Therefore, the second wire rod 12 of the winding portion 15a is unraveled, reducing the frictional force with the held portion, and the second wire rod 12 is prevented from shifting out of position from the held portion.

[0041] In a living body where the stent 1a is placed, the stent 1a moves in conjunction with, for example, intestinal movement or body movement, and external forces from the body lumen in which it is placed act on the first wire rod 11 and the second wire rod 12. Because the second wire rod 12 has lower rigidity than the first wire rod 11, the second wire rod 12 moves more than the first wire rod 11 when subjected to external forces from the body lumen. In the stent 1a of the second embodiment, the second wire 12 is held by the held portion of the first wire 11 by the first holding portion 15. Therefore, according to the second embodiment, it is possible to prevent the second wire 12 from slipping on the first wire 11 and loosening the fixation of the second wire 12. Furthermore, according to the second embodiment, the state in which the second wire 12 is held by the held portion of the first wire 11 is maintained, so that gaps in the stent 1a are less likely to widen even when subjected to external force from the biological lumen. Therefore, according to the second embodiment, for example, the possibility of biological tissue infiltrating into the stent due to widening of the axial distance between the annular formation portions 13 connected by the second wire 12 or the mesh of the first wire 11 and the second wire 12 is reduced.

[0042] (Third embodiment) FIG. 9 is a diagram showing an example of the configuration of a stent 1b of the third embodiment. Similar to the stent 1 of the first embodiment, the stent 1b of the third embodiment is formed into a cylindrical shape by combining a first wire rod 11 and a second wire rod 12, and has a plurality of annular formation portions 13 formed from the first wire rod 11 in the axial direction. The annular formation portions 13 are connected to an annular formation portion 13 separated by one annular formation portion 13 in the axial direction by a second wire rod 12, straddling adjacent annular formation portions 13. These two annular formation portions 13 are connected by the second wire rod 12 at the peak portion 11a of one annular formation portion 13 and the valley portion 11b of the other annular formation portion 13. Furthermore, the second wire rod 12 and the first wire rod 11 intersect to form a mesh in the stent 1b.

[0043] In a stent 1b of the third embodiment, a second wire 12 connecting a peak 11a of one annular formation portion 13 to a valley 11b of the other annular formation portion 13 is held by an annular formation portion 13 disposed between the one annular formation portion 13 and the other annular formation portion 13. Specifically, a second holding portion 16 for holding the intersecting second wire 12 is formed in an intermediate portion 11c between adjacent peaks 11a and valleys 11b in one annular formation portion 13. Figure 9 shows an example in which the second holding portion 16 is formed by tying intersecting second wires 12 to the intermediate portion 11c of the annular formation portion 13.

[0044] In the third embodiment, the second holding portion 16 is formed at the intersection of the intermediate portion 11c of the annular forming portion 13 and the second wire rod 12, and the distance at which the second wire rod 12 is held by the first wire rod 11 is smaller than when there is no second holding portion 16. This reduces slack in the second wire rod 12, making it possible to prevent the second wire rod 12 from separating from the annular forming portion 13. Therefore, according to the third embodiment, when the stent 1b is subjected to an external force from a biological lumen or when the stent 1b is placed, the possibility of the bent second wire rod 12 becoming entangled in the annular formation portion 13 is reduced. Furthermore, according to the third embodiment, the possibility of the second wire rod 12, bent toward the inner periphery, getting caught on and interfering with a stent delivery system or the like can be reduced.

[0045] Furthermore, the configuration of the second retaining portion 16 of the third embodiment is not limited to the example in Fig. 9. For example, the second retaining portion 16 may be formed by binding the intersecting portion of the intermediate portion 11c of the annular formation portion 13 and the second wire rod 12 using another member such as a suture, or the second retaining portion 16 may be formed by bonding the intersecting portion of the intermediate portion 11c of the annular formation portion 13 and the second wire rod 12 with a biocompatible adhesive. When the second holding portion 16 is formed by adhesion, the adhesive strength may be adjusted so that the second wire rod 12 detaches from the intermediate portion 11c when the second wire rod 12 receives an external force of a predetermined magnitude or greater. This prevents a large load from being applied to the second wire rod 12 when the stent 1b is deformed, thereby reducing the possibility of damage to the second wire rod 12.

[0046] 10 is a diagram showing another example of the second holding portion of the third embodiment. The second holding portion 16a shown in Fig. 10 has a loop portion 17 formed of the second wire rod 12, the loop portion 17 being larger in size than the circumferential length of the first wire rod 11, and the first wire rod 11 is inserted through the loop portion 17. As a result, the second wire rod 12 is held in the vicinity of the first wire rod 11 via the second holding portion 16a, and the second holding portion 16a can slide in the extension direction of the first wire rod 11.

[0047] The second holding portion 16a in Fig. 10 can prevent the second wire rod 12 from separating from the annular formation portion 13. Furthermore, when the stent 1b is deformed, the second holding portion 16a slides in the extension direction of the first wire rod 11, and the position of the second holding portion 16a changes in accordance with the deformation of the stent 1c. Therefore, the second holding portion 16a is less likely to apply a large load to the second wire rod 12, and the possibility of damaging the second wire rod 12 is reduced. Note that the second holding portion 16a in Fig. 10 may be formed using a material different from that of the second wire rod 12.

[0048] The present invention is not limited to the above-described embodiments, and various improvements and design changes may be made without departing from the spirit of the present invention. For example, the configurations of the second and third embodiments may be combined.

[0049] The annular formation portions 13 of the stent 1 do not necessarily have to be connected in an annular shape as long as the first wire rod 11 is wound around in the circumferential direction. For example, the first wire rod 11 bent in a zigzag shape may be wound spirally to form a plurality of annular formation portions 13, and the bent portions of these annular formation portions 13 may be connected in the axial direction by the second wire rod 12 to form the stent 1. In other words, the stent 1 does not necessarily have to include the crossover portion 14, and whether or not it includes the crossover portion 14 can be changed as appropriate.

[0050] Furthermore, 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 by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0051] 1, 1a, 1b... stent, 2... digestive tract (biological lumen), 2a... lesion site, 11... first wire rod, 11a... peak portion (bent portion), 11b... valley portion (bent portion), 11c... intermediate portion, 12... second wire rod, 13... annular formation portion, 14... crossover portion, 15... first holding portion, 15a... winding portion, 15b... knot, 16, 16a... second holding portion, 17... loop portion

Claims

1. A stent to be placed in a biological lumen, The wire is formed into a cylindrical shape by combining first and second wire rods made of different materials, the first wire rod has a predetermined rigidity; The second wire member has a relatively low rigidity compared to the first wire member.

2. the first wire is formed from a material containing metal; 2. The stent according to claim 1, wherein the second wire material has a relatively low metal content compared to the first wire material, or is formed from a material that does not contain metal.

3. a plurality of annular formation portions formed by extending the first wire rod along the circumferential direction of the stent; The stent according to claim 1 or 2, wherein the plurality of annular formation portions are arranged side by side in the axial direction of the stent and are connected in the axial direction by the second wire material.

4. the annular forming portion has a bent portion where the first wire rod is bent in the axial direction, 4. The stent according to claim 3, wherein the bent portions of the plurality of annular formation portions are connected to each other by the second wire.

5. 5. The stent according to claim 4, wherein the bent portions of two of the plurality of annular formation portions that are not adjacent to each other in the axial direction are connected to each other by the second wire.

6. the annular forming portion has a first holding portion that connects the second wire to the bent portion, The first holding portion includes a winding portion in which the second wire is wound around the first wire a plurality of times in a state in which the second wire is in close contact with the first wire, and a knot that bundles and fixes the second wire of the winding portion.

5. The stent of claim 4.

7. The annular forming portion has a second holding portion between the bent portions adjacent in the circumferential direction, the second holding portion holding the second wire rod intersecting the first wire rod.

5. The stent of claim 4.

8. The second holding portion separates the second wire rod from the first wire rod when the second wire rod receives an external force equal to or greater than a predetermined value.

8. The stent of claim 7.

9. The second holding portion is slidable in the extension direction of the first wire rod.

8. The stent of claim 7.

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