Synthetic resin stent and stent delivery system

Abstract

A synthetic resin stent is provided that can exhibit self-expandability, restorability, close adhesion to the digestive tract, and tracking performance relative to peristaltic motion. The synthetic resin stent (1) comprises: a first stent body (3) formed of synthetic resin fibers into a tubular shape having meshes and capable of being deformed from a reduced diameter state to an expanded diameter state, and a second stent (5) formed into a tubular shape having meshes denser than those of the first stent body (3), arranged to cover the outer circumference of the first stent body (3), and capable of being deformed from a reduced diameter state to an expanded diameter state.

Description

Technical Field

[0001] The present invention relates to a synthetic resin stent such as a biodegradable stent and a stent delivery system. Background Art

[0002] In the past, for stenotic diseases (tumors, inflammation, etc.) of biological channels such as blood vessels and the digestive tract, a treatment was performed by placing a stent in the stenotic part to dilate the stenotic part. As stents, for example, stents made of metal or synthetic resin are known. Among them, metal stents require surgical operation when they are pulled out from the body, which places a great burden on the patient. Therefore, the use of metal stents is limited to cases such as malignant tumors that are planned to be semi-permanently placed or surgically operated. Based on this background, a biodegradable stent as a synthetic resin stent has been proposed as a stent for use in cases where metal stents cannot be used.

[0003] Since synthetic resin stents are inferior to metal stents in self-expandability, recovery, adhesion to the digestive tract such as the intestines, and followability to the peristaltic movement of the digestive tract, when synthetic resin stents are made in the same shape as metal stents, they sometimes cannot exhibit the required performance.

[0004] In this regard, for example, it is disclosed to coat a stent formed by processing a biodegradable resin into a zigzag shape and connecting the stents with a film (see, for example, Patent Document 1).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2003-52834 Summary of the invention

[0008] Problems to be solved by the invention

[0009] However, in the stent described in Patent Document 1, since a film is added to cover it, it is difficult to reduce the diameter when the stent is reduced in diameter. In addition, since the stent described in Patent Document 1 is formed by processing a biodegradable resin into a zigzag shape and connecting them, it is difficult to achieve a balance between the two ends where the followability and recovery relative to the peristaltic motion of the digestive tract are important and the central part where pressure strength is required. Therefore, a synthetic resin stent that can exert self-expandability, recovery, close adhesion to the digestive tract, and followability relative to the peristaltic motion of the digestive tract is desired.

[0010] Therefore, an object of the present invention is to provide a synthetic resin stent and a stent delivery system that can exhibit self-expandability, restorability, adhesion to the digestive tract, and followability to peristaltic motion.

[0011] Means for solving problems

[0012] The present invention relates to a synthetic resin bracket, comprising: a first bracket, the first bracket having a first bracket main body portion formed of synthetic resin fibers into a cylindrical shape having meshes, and capable of being deformed from a reduced diameter state to an expanded diameter state; and a second bracket, the second bracket being formed into a cylindrical shape having meshes denser than those of the first bracket main body portion, and being arranged in a manner covering the outer periphery of the first bracket main body portion, and the second bracket being capable of being deformed from a reduced diameter state to an expanded diameter state.

[0013] In addition, it is preferred that a plurality of polygonal ring portions formed from synthetic resin fibers into polygonal rings when viewed along the length direction are arranged and connected in the length direction of the first bracket in a state where they are bent or curved so as to become convex along the length direction, thereby forming the first bracket main body portion.

[0014] In addition, preferably, the first stent further includes an end portion with an expanded diameter, the end portion with an expanded diameter connected to at least one end portion in the longitudinal direction of the first stent main body and having a larger diameter than the first stent main body.

[0015] In addition, it is preferred that in the main body of the first bracket, a plurality of polygonal ring portions formed by fibers made of synthetic resin into polygonal rings when viewed along the length direction are arranged and connected in the length direction of the first bracket in a state of being bent or curved in a manner to become convex along the length direction, and the end diameter expansion portion is composed of fibers made of synthetic resin having a smaller diameter than the main body of the first bracket in a polygonal ring structure having more sides than the polygonal ring portions.

[0016] In addition, preferably, the first stent is a stent having an end flare portion arranged at an end in the axial direction and formed by a wire, and the end flare portion is continuously arranged in a circumferential direction with a plurality of mountain portions consisting of a front end corner portion protruding outward in the axial direction, so that the end flare portion is formed into a ring shape when observed along the axial direction, and when the stent is left in the digestive tract, an angle formed by two sides constituting the mountain portion is less than 80°, and the number of the plurality of mountain portions is 3 to 11.

[0017] In addition, it is preferable that the two sides constituting the mountain portion are constituted by two sides of an end lattice disposed at an end in the axial direction.

[0018] In addition, it is preferable that the first bracket has a plurality of grids arranged in an axial direction, and the end grid is arranged at an end of the plurality of grids.

[0019] In addition, it is preferable that the length of one side of the two sides constituting the mountain portion is 16 to 22 mm.

[0020] In addition, it is preferable that the adjacent peak portions in the end flared portion are fixed to each other at an intersection on the endmost side in the axial direction.

[0021] In addition, it is preferred that the second bracket is a synthetic resin bracket having a first woven component and a second woven component, the first woven component is a tubular woven component woven into a mesh shape and formed by a plurality of fibers, the second woven component is woven and arranged on the first woven component and is annular and formed by a plurality of fibers, the first woven component has a plurality of first fibers extending at a predetermined angle inclined relative to the axial direction, a plurality of second fibers extending crosswise relative to the first fibers, and a plurality of first intersections formed by the intersection of the plurality of first fibers and the plurality of second fibers, the second woven component has a plurality of third fibers in a wavy shape arranged separately in the axial direction and a plurality of fourth fibers in a wavy shape arranged separately in the axial direction, and at least one of the plurality of first intersections is arranged in an intersection area surrounded by the third fibers and the fourth fibers.

[0022] In addition, preferably, a plurality of the intersection regions are arranged in a circumferential direction of the first knitted component, a plurality of the first intersection points are arranged in a circumferential direction of the first knitted component, and the plurality of the first intersection points are respectively arranged in a plurality of the intersection regions.

[0023] In addition, it is preferred that in the structure in which the first intersection point is arranged in the intersection area, the third fiber is arranged in the following state: with respect to movement in the direction in which the overlapping portion of the third fiber and the fourth fiber becomes smaller, the third fiber can be hooked on one or more fibers among the first fiber, the second fiber and the fourth fiber, and the fourth fiber is arranged in the following state: with respect to movement in the direction in which the overlapping portion of the third fiber and the fourth fiber becomes smaller, the fourth fiber can be hooked on one or more fibers among the first fiber, the second fiber and the third fiber.

[0024] In addition, it is preferred that there are multiple structures for configuring the first intersection point in the intersection area, and at least a portion of the synthetic resin support includes the following structure, in which the third fiber and the fourth fiber are configured in the following state: they can hook each other with respect to movement in a direction in which the overlapping portion of the third fiber and the fourth fiber becomes smaller, and they are not hooked to the first fiber and the second fiber with respect to the movement of the third fiber and the fourth fiber.

[0025] In addition, preferably, at the top of the mountain portion in the wavy third fiber and / or the fourth fiber, there is formed an annular ring portion arranged in a manner to surround any one or more of the first fiber, the second fiber, the third fiber and the fourth fiber.

[0026] Furthermore, it is preferable that the second knitted component part is formed of fibers made of synthetic resin having a higher expansion force than that of the first knitted component part.

[0027] In addition, it is preferred that the second bracket is a synthetic resin bracket having a first woven component and a second woven component, the first woven component being a tubular woven component that is mesh-shaped and formed of one or more fibers, the second woven component being woven and arranged on the first woven component and being annular and formed of one or more fibers, the first woven component having a plurality of first fibers that are inclined at a predetermined angle relative to the axial direction and extend in an axial direction with repeated bending, a plurality of second fibers that are arranged to have a portion that intersects with the first fibers and extend in an axial direction with repeated bending, and a plurality of first intersection regions formed by the intersection of the plurality of first fibers and the plurality of second fibers, the second woven component having a plurality of third fibers that are inclined at a predetermined angle relative to the axial direction and extend in a circumferential direction with repeated bending, a plurality of fourth fibers that are arranged to have a portion that intersects with the third fibers and extend in an axial direction with repeated bending, and a plurality of second intersection regions formed by the intersection of the plurality of third fibers and the plurality of fourth fibers, and at least a portion of the first intersection region and the second intersection region are arranged to overlap.

[0028] In addition, preferably, in a structure in which the first intersection region and the second intersection region are overlapped, the first fiber is configured in a state where the first fiber can be hooked on one or more of the third fiber and the fourth fiber with respect to movement in a direction in which the overlapping portion of the first fiber and the second fiber becomes smaller, and the second fiber is configured in a state where the second fiber can be hooked on one or more of the third fiber and the fourth fiber with respect to movement in a direction in which the overlapping portion of the first fiber and the second fiber becomes smaller.

[0029] In addition, the present invention relates to a stent delivery system for placing the synthetic resin stent in a living body, comprising: an outer cylinder, which is capable of accommodating the first stent and the second stent on the inner side, and the second stent and the first stent are arranged in sequence from the front end side; and a pushing member, which is arranged on the inner side of the outer cylinder and is capable of pushing the second stent and the first stent out from the front end side of the outer cylinder in sequence.

[0030] Effects of the Invention

[0031] According to the present invention, it is possible to provide a synthetic resin stent and a stent delivery system having self-expandability, restorability, adhesion to the digestive tract, and followability to peristaltic movement. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a perspective view showing a biodegradable stent according to a first embodiment of the present invention.

[0033] Figure 2 It is a perspective view showing the inner bracket according to the first embodiment.

[0034] Figure 3 It is a perspective view showing the outer bracket according to the first embodiment.

[0035] Figure 4 It is a perspective view showing a biodegradable stent according to a second embodiment.

[0036] Figure 5 It is a perspective view showing an inner bracket according to the second embodiment.

[0037] Figure 6 The figures are graphs showing the values ​​of the front end angle and the length of one side corresponding to the spacing and the number of peaks for the end flare portion of a stent made of fibers having a fiber diameter of φ0.4 mm in the inner stent of the second embodiment. (a) is a graph showing the values ​​in the retained state, and (b) is a graph showing the values ​​in the state installed on the core rod.

[0038] Figure 7 This figure shows the positional deviation relative to the peristaltic movement of the intestine when the biodegradable stent is left in the intestine, when the inner stent of the second embodiment is made of a fiber with a fiber diameter of φ0.4 mm and the front end angle and the length of one side in the end flared portion are changed.

[0039] Figure 8 This figure shows the positional deviation relative to the peristaltic movement of the intestine when the biodegradable stent is left in the intestine, when the inner stent of the second embodiment is made of a fiber with a fiber diameter of φ0.5 mm and the front end angle and the length of one side in the end flared portion are changed.

[0040] Fig. 9 It is a perspective view showing an outer bracket according to the second embodiment.

[0041] Fig.10 yes Fig. 9 An enlarged view of the outer bracket is shown.

[0042] Fig.11It is a diagram showing an outer bracket according to a first modified form of the second embodiment.

[0043] Fig.12 It is a diagram showing an outer bracket according to a second modified form of the second embodiment.

[0044] Fig.13 It is a diagram showing an outer bracket according to a third modified form of the second embodiment.

[0045] Fig.14 This is a perspective view showing a biodegradable stent according to a fourth modified form of the second embodiment of the present invention.

[0046] Fig.15 yes Fig.14 A magnified image of the biodegradable scaffold is shown. DETAILED DESCRIPTION

[0047] <First Embodiment>

[0048] Hereinafter, a preferred first embodiment of the synthetic resin bracket of the present invention will be described with reference to the drawings. Figure 1 It is a perspective view showing the biodegradable stent 1 according to the first embodiment of the present invention. Figure 2 It is a perspective view showing the inner bracket 2 according to the first embodiment. Figure 3 1 is a perspective view showing the outer stent 5 of the first embodiment. In the description of this embodiment, the direction in which the biodegradable stent 1 as a whole extends is referred to as the longitudinal direction X, and the direction perpendicular to the longitudinal direction X is referred to as the longitudinal direction X. Figure 1 The up-down direction in FIG. 1 is referred to as a first direction D1 , and the direction perpendicular to the length direction X and the first direction D1 is referred to as a second direction D2 .

[0049] The synthetic resin stent of this embodiment is a biodegradable stent 1 composed of biodegradable fibers, such as Figure 1 to Figure 3 As shown in FIG. 1 , an inner bracket 2 (first bracket) and a cylindrical outer bracket 5 (second bracket) are provided. A portion of the inner bracket 2 on the central side in the longitudinal direction X is arranged on the inner side of the outer bracket 5 .

[0050] The inner bracket 2 is formed to extend in the longitudinal direction X and can be deformed from a reduced diameter state to an expanded diameter state. The inner bracket 2 has an inner bracket body 3 (first bracket body) formed to extend in the longitudinal direction X as a whole and a pair of end flared portions 4 (end expanded diameter portions).

[0051] like Figure 2As shown, the inner bracket body 3 is formed into a tubular shape having meshes by synthetic resin fibers constituting a plurality of polygonal annular portions 311. The inner bracket body 3 is formed by connecting a plurality of polygonal annular portions 311. More specifically, the inner bracket body 3 is formed by connecting a plurality of three-dimensional shape portions 31 constituted by a pair of polygonal annular portions 311.

[0052] like Figure 2 As shown in FIG. 1 , the three-dimensional shape portion 31 is formed by connecting a pair of polygonal annular portions 311 in the longitudinal direction X. The polygonal annular portion 311 is formed by bending the annular portion at a pair of bending portions 312 in the center in the first direction D1 and a pair of bending portions 313 in the center in the second direction D2. The bending portions 312 and 313 are formed by the mountain portion and the valley portion of the polygonal annular portion 311.

[0053] The polygonal annular portion 311 is formed into a quadrilateral shape, and in the present embodiment, for example, is formed into a substantially rhombus shape when viewed along the longitudinal direction X. The pair of bent portions 312 and the pair of bent portions 313 constituting the top of the polygonal annular portion 311 are bent in a substantially V-shaped manner that is convex toward one side or the other side in the longitudinal direction X when viewed along the first direction D1 and when viewed along the second direction D2.

[0054] A polygonal annular portion 311 is configured such that a pair of bent portions 312 are bent and positioned so that the center in the first direction D1 becomes convex toward one side in the longitudinal direction X, and a pair of bent portions 313 are bent and positioned so that the center in the second direction D2 becomes convex toward the other side in the longitudinal direction.

[0055] In addition, another polygonal annular portion 311 arranged next to a polygonal annular portion 311 is arranged to bend toward the opposite side of the polygonal annular portion 311 at a pair of bend portions 312 and a pair of bend portions 313, and the pair of bend portions 312 are bent and positioned in a manner that becomes a convex toward the other side in the length direction X from the center in the first direction D1, and the pair of bend portions 313 are bent and positioned in a manner that becomes a convex toward one side in the length direction from the center in the second direction D2.

[0056] The three-dimensional shape portion 31 is formed by connecting the pair of bent portions 313 of the adjacent polygonal annular portions 311 to each other at the center in the second direction D2 by the cylindrical connecting portion 32 in a state where the projections of the pair of bent portions 313 of the adjacent polygonal annular portions 311 face each other. When viewed along the second direction D2, the inner side portions of the recesses of the adjacent polygonal annular portions 311 are formed into a substantially rhombus shape.

[0057] The inner bracket body 3 is formed by arranging a plurality of three-dimensional shape parts 31 in the longitudinal direction X and connecting them. The adjacent three-dimensional shape parts 31 are arranged so that the projections of the pair of bent parts 312 of the adjacent polygonal annular parts 311 face each other, and the pair of bent parts 312 of the adjacent polygonal annular parts 311 are connected to each other at the center in the first direction D1 by the cylindrical connecting part 32. When viewed along the first direction D1, the inner side of the recessed parts of the polygonal annular parts 311 of the adjacent three-dimensional shape parts 31 are formed into a substantially rhombus shape.

[0058] The inner stent body 3 has a structure in which a plurality of polygonal annular portions 311 are connected to form a plurality of substantially rhombus-shaped meshes by synthetic resin fibers constituting the plurality of polygonal annular portions 311. In this way, the plurality of polygonal annular portions 311 formed by synthetic resin fibers in polygonal annular shapes when viewed in the longitudinal direction X are arranged and connected in the longitudinal direction X of the inner stent body 3 in a state of being bent so as to be convex in the longitudinal direction X, thereby forming the inner stent body 3.

[0059] The inner support body 3 is configured to be deformable between a state of reduced diameter and a state of expanded diameter. Here, the protrusions of synthetic resin fibers of a pair of adjacent polygonal annular portions 311 are connected to each other at a tubular connection portion 32 that connects a pair of bending portions 312 to each other, and the protrusions of synthetic resin fibers of adjacent polygonal annular portions 311 are connected to each other at a tubular connection portion 32 that connects a pair of bending portions 313 to each other. Therefore, the synthetic resin fibers forming the polygonal annular portions 311 exert a force that restores the portion bent at the tubular connection portion 32 to a straight shape ( Figure 2 As a result, the synthetic resin fiber bent at the tubular connection portion 32 is restored to a straight line extending in the first direction D1 and the second direction D2 (a direction intersecting the longitudinal direction X of the inner stent body 3). Therefore, the inner stent body 3 is subjected to a radially expanding force, and can stably press the narrow part.

[0060] In the inner stent body 3, the number of valleys of the polygonal annular portion 311 constituting the three-dimensional shape portion 31 is about 4 to 8 in the case of a small intestine stent, for example. In the present embodiment, when viewed in the longitudinal direction X of the inner stent body 3, the polygonal annular portion 311 is formed into a quadrilateral shape by thick-diameter fibers, and the number of valleys of the polygonal annular portion 311 is, for example, four.

[0061] It should be noted that the shape of the inner bracket body 3 is not particularly limited. For example, a structure in which synthetic resin fibers are processed into a zigzag shape and connected in the longitudinal direction can be considered. In the case of a zigzag shape, the number of valleys in the zigzag shape is not particularly limited, and preferably 4 to 8.

[0062] A pair of end horn portions 4 are respectively connected to the two ends of the inner stent body 3 in the length direction X, and are formed into a sawtooth shape of a polygonal annular structure with a plurality of sides having more valleys than the polygonal annular portion 311 of the inner stent body 3. A pair of end horn portions 4 are respectively arranged on the outer side of the outer stent 5 in the length direction X to abut against the healthy part. The end horn portion 4 extends in a first direction D1 intersecting the length direction X of the inner stent body 3 and is formed to be larger in diameter than the inner stent body 3, and can be deformed from a reduced diameter state to an expanded diameter state. The end horn portion 4 is formed by alternating mountain portions and valley portions in a direction intersecting the length direction X of the inner stent body 3.

[0063] The end flared portion 4 is connected to both ends of the inner stent body 3 by the cylindrical connecting portion 32 at a bent portion 412 that is convex toward the inner stent body 3 side.

[0064] The end flared portion 4 contacts the healthy portion, so the tracking and restoring properties relative to the peristaltic motion of the digestive tract such as the intestine are emphasized. Therefore, the end flared portion 4 is formed of a synthetic resin fiber having a diameter thinner than that of the inner stent body 3. When observed along the length direction X, the end flared portion 4 is formed of a polygonal annular structure having more sides than the polygonal annular portion 311 of the inner stent body 3, and when observed along the second direction D2, it is formed into a sawtooth shape having a plurality of hills and valleys, and the hills and valleys are formed of a plurality of bends 412 and 413 in the polygonal annular structure.

[0065] The end horn portion 4 is formed of a sawtooth shape of a polygonal annular structure having more valleys than the polygonal annular portion 311 of the inner support body 3. When the number of valleys of the inner support body 3 is set to a, the number of valleys of the end horn portion 4 is preferably na (n: integer), and more preferably 2n. In the present embodiment, the number of valleys of the polygonal annular structure of the end horn portion 4 is formed to be 8, for example. The end horn portion 4 can be provided at both ends of the inner support body 3, or only at one end.

[0066] The material of the synthetic resin fiber constituting the inner stent body 3 and the end horn 4 is not particularly limited, and a material with high recovery is preferred. For example, if a biodegradable resin is used, homopolymers, copolymers, and blended polymers composed of L-lactic acid, D-lactic acid, DL-lactic acid, glycolic acid, ε-caprolactone, and para-dioxanone can be cited. It should be noted that even non-biodegradable resins can be used as long as the material is high in recovery. In particular, as the material of the fiber constituting the inner stent body 3 and the end horn 4, for example, polydioxanone (PDO) is preferably used.

[0067] In addition, the synthetic resin fibers constituting the inner stent body 3 and the end flared portion 4 are not particularly limited and may be monofilament yarns or multifilament yarns. It should be noted that, from the viewpoint of enhancing the repulsive force of the stenosis in the living body against the pressure applied from the radially outer side of the inner stent body 3, the synthetic resin fibers constituting the inner stent body 3 are preferably monofilament yarns. In addition, the synthetic resin fibers constituting the inner stent body 3 and the end flared portion 4 may be twisted or not.

[0068] The fiber diameter of the synthetic resin fiber constituting the above-mentioned inner stent body portion 3 and the end flared portion 4 is, for example, 0.05 to 0.7 mm, or preferably 0.4 to 0.6 mm.

[0069] In addition, the fiber diameter of the synthetic resin fiber constituting the end flared portion 4 is preferably the same as or smaller than the fiber diameter of the synthetic resin fiber constituting the inner stent body portion 3 .

[0070] The size of the inner stent body 3 is not particularly limited, and for example, the diameter in the expanded state is 10 to 25 mm, and the length is 30 to 250 mm.

[0071] like Figure 3 As shown in FIG. 1 , the outer bracket 5 is formed by weaving fibers made of synthetic resin into a cylindrical shape extending in the longitudinal direction X (predetermined direction). Figure 1 As shown, the outer bracket 5 is configured to cover the outer periphery of the inner bracket body 3 of the inner bracket 2. The outer bracket 5 is formed of synthetic resin fibers having a finer diameter than the inner bracket body 3 of the inner bracket 2, and has a denser mesh than the inner bracket body 3 of the inner bracket 2. The outer bracket 5 can be deformed from a state of reduced diameter to a state of expanded diameter.

[0072] The material of the synthetic resin fiber constituting the outer support 5 is not particularly limited, and a material with high rigidity is preferably used. For example, if a biodegradable resin is used, homopolymers, copolymers, and blended polymers composed of L-lactic acid, D-lactic acid, DL-lactic acid, glycolic acid, ε-caprolactone, and p-dioxanone can be cited. It should be noted that even if it is a non-biodegradable resin, it can be used as long as it is a material with high rigidity. In particular, as the material of the fiber constituting the outer support 5, for example, poly L-lactic acid (PLLA) is preferably used. In the present embodiment, the fiber constituting the outer support 5 is formed of, for example, poly L-lactic acid (PLLA).

[0073] The shape of the outer stent 5 is not particularly limited, and it is, for example, a structure formed by weaving fibers made of synthetic resin. The end of the outer stent 5 is not particularly limited, and it is preferably a shape with rich self-expandability. It should be noted that the outer stent 5 may not have self-expandability, restorability, and tracking property relative to peristaltic motion.

[0074] When the biodegradable stent 1 is placed in the digestive tract, first, the outer stent 5 is placed in the digestive tract in a compressed state. Thus, the outer stent 5 is placed in the digestive tract with its diameter expanded. Thereafter, the inner stent 2 is placed in the inner side of the outer stent 5 in a compressed state. Therefore, in a state where the inner stent body 3 of the inner stent 2 is arranged in the inner side of the outer stent 5, the inner stent 2 and the outer stent 5 are placed in an overlapping manner.

[0075] More specifically, the biodegradable stent 1 is placed in the digestive tract using the stent delivery system. The stent delivery system of this embodiment includes a sheath member (outer cylinder) (not shown) inserted into the digestive tract and a pressing member (not shown).

[0076] The inner stent 2 and the outer stent 5 can be housed inside the outer sheath member. The outer stent 5 and the inner stent 2 are arranged in a straight line in order from the distal end side to the proximal end side inside the outer sheath member in a compressed state.

[0077] In this state, the outer stent 5 and the inner stent 2 are sequentially pushed out from the front end side of the outer sheath member by the pressing member disposed at the base end side of the inner side of the outer sheath member. Thus, first, the outer stent 5 is pushed out from the front end side of the outer sheath member, expands in diameter inside the digestive tract, and is retained inside the digestive tract. Thereafter, the inner stent 2 is further pressed by the pressing member, so that the inner stent 2 is pushed out from the front end side of the outer sheath member, expands in diameter inside the outer stent 5, and is retained inside the outer stent 5.

[0078] In this way, when the biodegradable stent 1 is retained, the inner stent 2 is retained on the inner side of the outer stent 5 after the outer stent 5 is retained, so that the inner stent 2 pushes the outer stent 5 toward the digestive tract at the inner stent body 3, and can push the digestive tract at the outer end flared portion 4 in the length direction X arranged at both ends of the outer stent 5.

[0079] Here, with respect to the biodegradable stent 1 of the present invention, the reason for configuring the outer stent 5 having a cylindrical shape with a dense mesh made of fibers (fine-diameter fibers) made of synthetic resin having a diameter thinner than the inner stent main body 3 in a manner that covers the outer periphery of the inner stent main body 3 having a cylindrical shape with a sparse mesh made of fibers (thick-diameter fibers) made of synthetic resin having a relatively large diameter, is explained.

[0080] When a stent is made of a synthetic resin such as a biodegradable resin, fibers with a relatively small diameter are used from the viewpoint of ensuring the ability to be accommodated in a delivery sheath. In this case, the strength of the manufactured stent cannot be sufficiently ensured.

[0081] Therefore, in the present invention, the bracket 1 is constructed by covering the outer periphery of the inner bracket main body 3 which is formed of fibers (thick diameter fibers) made of synthetic resin with a relatively large diameter and having a sparse mesh, and configuring an outer bracket 5 which is formed of fibers (thin diameter fibers) made of synthetic resin with a smaller diameter than the inner bracket main body 3 and having a denser mesh than the inner bracket main body 3.

[0082] Thus, by arranging the inner stent body 3 formed of thick-diameter fibers with a sparse mesh inside the outer stent 5 formed of fine-diameter fibers with a dense mesh, the inner stent body 3 pushes the outer stent 5 from the inside of the outer stent 5. Therefore, the strength of the outer stent 5 is enhanced by the pushing force of the inner stent body 3 from the inside of the outer stent 5, and the strength of the entire biodegradable stent 1 can be ensured.

[0083] Furthermore, by configuring the inner stent 2 formed of thick-diameter fibers to have a coarse mesh, it is possible to ensure the ability to be accommodated in the delivery sheath.

[0084] In addition, an end trumpet portion 4 is arranged at the end (the portion that contacts the healthy portion) of the inner stent body 3, where the tracking and restoring properties relative to the peristaltic motion of the digestive tract are important. By forming the end trumpet portion 4 into a polygonal annular structure with more valleys than the polygonal annular portion 311 of the inner stent body 3 using fibers (thin-diameter fibers) made of a relatively fine diameter synthetic resin, it is easy to deform and the area of ​​close contact with the digestive tract is increased, thereby improving the tracking and restoring properties relative to the peristaltic motion of the digestive tract. In addition, even if the end trumpet portion 4 is formed into a polygonal annular structure with more valleys than the polygonal annular portion 311 of the inner stent body 3, since the end trumpet portion 4 is formed of fibers (thin-diameter fibers) made of a relatively fine diameter synthetic resin, the storage property into the delivery sheath can be ensured.

[0085] The above-mentioned production example of the biodegradable stent 1 will be briefly described.

[0086] In this manufacturing example, regarding the inner stent body 3 of the inner stent 2, the inner stent body 3 is manufactured by processing polydioxanone (PDO) having a fiber diameter of 0.5 mm into a quadrilateral shape (zigzag shape) (number of valleys: 4) and manufacturing a polygonal annular portion 311, and arranging the polygonal annular portions 311 having different bending directions in the longitudinal direction X so as to alternately form six pairs in the longitudinal direction X, thereby manufacturing a three-pair three-dimensional shape portion 31. In this way, the inner stent body 3 having a core rod diameter of 20 mm is manufactured.

[0087] In addition, the end horn portion 4 of the inner bracket 2 is made of the same fiber diameter and material as the inner bracket body 3 and is made into a polygonal annular structure in a sawtooth shape (number of valleys: 8), and is connected to the two ends of the inner bracket body 3.

[0088] In addition, regarding the outer stent 5, an outer stent 5 woven with PLLA fibers (0.25 mm and 0.3 mm) was produced.

[0089] Then, the biodegradable stent 1 can be manufactured by disposing the inner stent 2 inside the outer stent 5 and overlapping and placing the outer stent 5 outside the inner stent 2 .

[0090] According to the biodegradable stent 1 of the present embodiment described above, the following effects are achieved.

[0091] (1a) A biodegradable stent 1 is constituted by an inner stent 2 and an outer stent 5, wherein the inner stent 2 has an inner stent body 3 formed of synthetic resin fibers in a cylindrical shape having meshes and capable of being deformed from a reduced diameter state to an expanded diameter state, and the outer stent 5 is formed in a cylindrical shape having meshes denser than the inner stent body 3 and arranged to cover the outer periphery of the inner stent body 3 and capable of being deformed from a reduced diameter state to an expanded diameter state. Therefore, by arranging the inner stent body 3 formed in a sparse mesh inside the outer stent 5 formed in a dense mesh, the strength of the outer stent 5 can be enhanced by the pressing force of the inner stent body 3 from the inside of the outer stent 5, thereby ensuring the strength of the biodegradable stent 1 as a whole. Thus, since the digestive tract can be pressed in a state where the strength of the biodegradable stent 1 as a whole is ensured by the pressing force of the inner stent body 3 from the inside of the outer stent 5, stenosis can be prevented and the movement of the biodegradable stent 1 can be prevented. Therefore, it is possible to realize a biodegradable stent 1 that can exhibit self-expandability, restorability, adhesion to the digestive tract, and ability to follow peristaltic motion.

[0092] (1b) The inner stent body 3 is formed by arranging and connecting a plurality of polygonal ring portions 311 formed of synthetic resin fibers in a polygonal ring shape when viewed in the longitudinal direction X in a state where the plurality of polygonal ring portions 311 are bent or curved so as to be convex in the longitudinal direction X in the inner stent body 3. Thus, a biodegradable stent 1 that can exhibit self-expandability, restorability, adhesion to the digestive tract, and followability to peristaltic motion can be realized with a simple structure.

[0093] In addition, the synthetic resin fiber forming the polygonal annular portion 311 exerts a force to restore the portion bent at the cylindrical connecting portion 32 to a straight line ( Figure 2 As a result, the synthetic resin fiber bent at the tubular connecting portion 32 is restored to a straight line extending in a direction intersecting the longitudinal direction of the inner stent body 3. Therefore, the inner stent body 3 can stably press the narrow part.

[0094] (1c) The inner stent 2 further includes an end horn 4 connected to the end of the inner stent body 3 in the longitudinal direction X and having a larger diameter than the inner stent body 3. Thus, the digestive tract can be stably pressed at the end horn 4. Therefore, the biodegradable stent 1 can be stably held in the digestive tract by the end horn 4 disposed at the end of the inner stent body 3 in the longitudinal direction X.

[0095] (1d) The end flared portion 4 is made of synthetic resin fibers having a diameter thinner than that of the inner stent body 3, and is formed into a polygonal annular structure having more sides than the polygonal annular portion 311 of the inner stent body 3. As a result, since the end flared portion 4 is easily deformed and the area of ​​close contact with the digestive tract is increased, the tracking and recovery properties relative to the movement of the digestive tract can be improved. In addition, since the end flared portion 4 is formed of synthetic resin fibers having a relatively fine diameter (thin-diameter fibers), the storage property in the delivery sheath can be ensured.

[0096] (1e) A stent delivery system for placing a biodegradable stent 1 in a living body, comprising an outer sheath member capable of accommodating an inner stent 2 and an outer stent 5 and arranging the outer stent 5 and the inner stent 2 in sequence from the front end side, and a pushing member arranged inside the outer sheath member and capable of pushing out the outer stent 5 and the inner stent 2 in sequence from the front end side of the outer sheath member. Thus, by using the pushing member to push out the outer stent 5 and the inner stent 2 in sequence, the biodegradable stent 1 can be easily placed inside the digestive tract.

[0097] <Second Embodiment>

[0098] Next, a second embodiment of the present invention will be described. Figure 4 1 is a perspective view showing a biodegradable stent 10 according to a second embodiment. The biodegradable stent 10 according to the second embodiment is mainly different in the structures of the inner stent 6 and the outer stent 11 .

[0099] The synthetic resin stent of the second embodiment is a biodegradable stent 10 composed of biodegradable fibers, such as Figure 4 As shown, there are an inner bracket 6 (first bracket) and an outer bracket 11 (second bracket) arranged outside the inner bracket 6. The central part of the inner bracket 6 in the longitudinal direction X (axial direction) is arranged inside the outer bracket 11. In the second embodiment, the description of the structure described in the first embodiment is omitted.

[0100] The biodegradable stent 10 of the second embodiment is similar to the biodegradable stent 1 of the first embodiment, and is composed of an inner stent 6 and an outer stent 11. The inner stent 6 has an inner stent main body 71 formed of synthetic resin fibers in a cylindrical shape with a mesh and capable of being deformed from a reduced diameter state to an expanded diameter state. The outer stent 11 is formed of synthetic resin fibers having a finer diameter than the inner stent main body 71 in a cylindrical shape with a denser mesh than the inner stent main body 71 and is arranged to cover the outer periphery of the inner stent main body 3 and capable of being deformed from a reduced diameter state to an expanded diameter state.

[0101] Next, the inner bracket 6 will be described. Figure 5 It is a perspective view showing the inner bracket 6 according to the second embodiment.

[0102] The inner support 6 of this embodiment is a biodegradable support made of biodegradable fibers, such as Figure 5 As shown, it is formed to extend in the longitudinal direction X (axial direction) and can be deformed from a state of reduced diameter to a state of expanded diameter. Figure 5 The inner support 6 is shown in a natural state. The inner support 6 can be Figure 5 The natural state shown is deformed into a state of reduced diameter, and when placed in the digestive tract in the state of reduced diameter, it is deformed from the state of reduced diameter to the state of expanded diameter according to the size of the digestive tract.

[0103] The inner bracket 6 is woven into a mesh shape by a plurality of fibers 60 (wires) and is formed into a cylindrical shape, and has a plurality of grids 61 formed by diamond-shaped holes and arranged in an orderly manner using the fibers 60 on the outer periphery. The plurality of grids 61 are arranged in the axial direction and in the circumferential direction. The mesh of the inner bracket 6 becomes sparse in the axial direction when the inner bracket 6 is in a state of shrinking diameter, and becomes dense in the axial direction when the inner bracket 6 is in a state of expanding diameter. In the present embodiment, the intersections where the woven fibers 60 intersect are fixed. As a fixing method, there are methods such as bonding and ultrasonic welding. At least the adjacent mountain portions 721 in the end horn portion 72 described later are fixed to each other at the intersections (intersections) on the endmost side in the axial direction. In the present embodiment, the inner bracket 6 is fixed at all the intersections where the woven fibers 60 intersect. Thereby, the compressive strength of the inner bracket 6 is improved.

[0104] It should be noted that the intersection where adjacent mountain portions 721 of the end flared portion 72 are fixed to each other may be where two straight fibers 60 cross and are fixed to each other, or may be where the vertices of the bend portion formed by two bent fibers 60 are fixed to each other.

[0105] The inner stent 6 includes an inner stent body 71 (first stent body) formed to extend in the longitudinal direction X as a whole, and an end flared portion 72 disposed at one end in the longitudinal direction X (axial direction) of the inner stent 6. The inner stent 6 is placed in the digestive tract in a state where a part of the inner stent body 71 is disposed inside the outer stent 11 and the end flared portion 72 is not covered by the outer stent 11.

[0106] The inner bracket body 71 is formed into a cylindrical shape having meshes by a plurality of lattices 61. The plurality of lattices 61 are arranged in parallel in the axial direction and in parallel in the circumferential direction. In the present embodiment, the plurality of lattices 61 are each composed of a rhombus-shaped hole.

[0107] In the present embodiment, the end horn 72 is provided only at one end of the inner stent 6 in the length direction. The end horn 72 contacts the healthy part of the digestive tract, so the tracking and restoring properties relative to the peristaltic motion of the digestive tract such as the intestine are emphasized, and the positional deviation after indwelling can be suppressed relative to the peristaltic motion of the digestive tract. It should be noted that in the present embodiment, the end horn 72 is arranged only at one end of the inner stent 6 in the axial direction, but it is not limited to this, and it can also be arranged at both ends of the inner stent 6 in the axial direction.

[0108] The end flared portion 72 is formed into a ring shape when viewed in the axial direction by continuously arranging a plurality of mountain portions 721 composed of a front end corner portion protruding outward in the axial direction at the end of one side of the inner bracket 6. More specifically, the plurality of mountain portions 721 are formed by bending the fiber 60 at the end of the inner bracket 6. The number of the plurality of mountain portions 721 is preferably 3 to 11, for example. In the present embodiment, the number of the plurality of mountain portions 721 is, for example, 3.

[0109] The two sides 721 a and 721 a of the mountain portion 721 are constituted by two sides 611 a and 611 a of an end lattice 611 arranged at an end in the axial direction among the plurality of lattices 61 arranged side by side in the axial direction.

[0110] The end flared portion 72 is formed such that, when the inner stent 6 is indwelled in the digestive tract, the front end angle θ (angle) formed by the two sides 611a, 611a of the end lattice 611 constituting the two sides 721a, 721a of the mountain portion 721 is less than 80°. The reason for setting the front end angle θ formed by the two sides 721a, 721a of the mountain portion 721 to less than 80° is based on the results of the evaluation test described later. When the front end angle θ formed by the two sides 721a, 721a of the mountain portion 721 is less than 80°, as shown in the results of the evaluation test described later, after repeating 10 times of the action simulating peristaltic motion, the positional deviation of the indwelling inner stent 6 relative to the peristaltic motion of the digestive tract is less than 1 cm.

[0111] In the present embodiment, the end trumpet 72 is formed such that the front end angle θ formed by the two sides 721a, 721a of the mountain 721 becomes less than 80° when the inner stent 6 is indwelled in the digestive tract, and the plurality of mountain portions 721 are continuously arranged in the circumferential direction in such a manner that the number of the plurality of mountain portions 721 is 3 to 11. The end trumpet 72 formed in this manner determines the density in the circumferential direction and the protruding length of the front end corner of the mountain portion 721 by the number of mountain portions 721 arranged in the circumferential direction and the front end angle θ formed by the two sides 721a, 721a of the mountain portion 721, and determines the shape formed continuously in the circumferential direction by the plurality of mountain portions 721 consisting of the front end corners protruding outward in the axial direction in a relatively sparse state. In the present embodiment, the end trumpet 72 is woven and formed in a sparser state than the inner stent main body 71 at the end of the inner stent 6.

[0112] As shown in the results of the evaluation test described later, since the position deviation of the inner stent 6 after placement relative to the peristaltic movement of the digestive tract of the end trumpet portion 72 constructed in this manner is less than 1 cm, it is possible to exhibit the ability to follow the peristaltic movement of the digestive tract and to suppress the position deviation after placement relative to the peristaltic movement of the digestive tract.

[0113] like Figure 5 As shown, in this embodiment, in the end flared portion 72, the axial distance (amplitude) between the apex of the mountain portion 721 and the apex of the valley portion 722 is referred to as the pitch P1. In the inner bracket body 71, the axial distance (amplitude) between the mountain portions protruding in the axial direction of the grid 61 is referred to as the pitch P2.

[0114] In the end flared portion 72 , the length of one side 721a of the two sides 721a and 721a constituting the peak portion 721 is referred to as a side length L. The side length L of the side 721a of the peak portion 721 is the length from the top of the peak portion 721 to the top of the valley portion 722 .

[0115] In the inner stent 6 of the present embodiment, the pitch P1 is formed to be larger in the end trumpet 72, and the pitch P2 is formed to be smaller than the pitch P1 of the end trumpet 72 in the inner stent body 71. For example, the ratio of the pitch P1 of the end trumpet 72 to the pitch P2 of the inner stent body 71 (pitch P1 / pitch P2) is preferably 3.3 to 7.0. Thus, the inner stent body 71 and the end trumpet 72 are formed without a sharp change in pitch. In addition, by making the ratio of the pitch P1 of the end trumpet 72 to the pitch P2 of the inner stent body 71 (pitch P1 / pitch P2) within the range of 3.3 to 7.0, it is possible to improve the tracking performance relative to the peristaltic movement of the digestive tract. The end trumpet 72 is arranged in the healthy part of the digestive tract, and the inner stent body 71 is arranged in the narrow part of the digestive tract.

[0116] The reason why the end flared portion 72 is disposed in the healthy part and the inner stent body portion 71 is disposed in the narrow part will be described below.

[0117] When the spacing P1 between the stents is large, even at a position where the diameter of the digestive tract is large, the mountain portion 721 is nearly parallel to the axial direction of the digestive tract, and can suppress the positional deviation of the stent after placement relative to the peristaltic movement of the digestive tract. In addition, since the mesh becomes sparse when the spacing P1 between the stents is large, the compressive strength becomes low. Therefore, by increasing the spacing P1, the positional deviation of the stent after placement relative to the peristaltic movement of the digestive tract can be suppressed even at a position where the diameter of the digestive tract is large. Here, a high compressive strength is not required for the stent placed in the healthy part. Therefore, the stent with a large spacing P1 is preferably placed in the healthy part of the digestive tract where the diameter is large and a high compressive strength is not required.

[0118] On the other hand, when the spacing P2 of the stents is small, if the diameter of the indwelling digestive tract becomes smaller, the mountain portion 721 is nearly parallel to the axial direction of the digestive tract, and the positional deviation of the indwelling stent can be suppressed relative to the peristaltic movement of the digestive tract. In addition, since the mesh becomes denser when the spacing P2 of the stents is small, the compression strength becomes higher. Here, a higher compression strength is required for the stents arranged in the narrow part. Therefore, the stents with a smaller spacing P2 are preferably arranged in the narrow part of the digestive tract where the diameter is small and a higher compression strength is required.

[0119] In addition, according to the results of the evaluation test described later, the length L of one side 721a of the two sides 721a, 721a of the mountain portion 721 constituting the end flared portion 72 is preferably in the range of 16 to 22 mm, for example. When the length L of one side 721a of the mountain portion 721 of the end flared portion 72 is in the range of 16 to 22 mm, as shown in the results of the evaluation test described later, since the positional deviation of the inner stent 6 after placement relative to the peristaltic movement of the digestive tract is less than 1 cm, the tracking property relative to the peristaltic movement of the digestive tract can be exerted, and the positional deviation after placement relative to the peristaltic movement of the digestive tract can be suppressed.

[0120] The material of the synthetic resin fiber 60 constituting the inner support body 71 and the end horn 72 is not particularly limited, and a material with high recovery is preferably used. For example, if a biodegradable resin is used, homopolymers, copolymers, and blended polymers composed of L-lactic acid, D-lactic acid, DL-lactic acid, glycolic acid, ε-caprolactone, p-dioxanone, and trimethylene carbonate can be cited. It should be noted that even non-biodegradable resins can be used as long as the material is high in recovery. In particular, as the material of the fiber constituting the inner support body 71 and the end horn 72, for example, polydioxanone (PDO) is preferably used.

[0121] In the present embodiment, the inner bracket 6 may be formed by, for example, connecting fibers extending in a zigzag shape in the axial direction in the circumferential direction, or may be formed by braiding a single fiber.

[0122] In addition, the synthetic resin fiber constituting the inner stent body 71 and the end flared portion 72 is not particularly limited, and may be either a monofilament yarn or a multifilament yarn. It should be noted that, from the viewpoint of enhancing the repulsive force of the stenosis in the living body against the pressure applied from the radially outer side of the inner stent body 71, the synthetic resin fiber constituting the inner stent body 71 is preferably a monofilament yarn.

[0123] The fiber diameter (diameter) of the synthetic resin fiber constituting the inner support body portion 71 and the end flared portion 72 described above is, for example, 0.05 to 0.7 mm, or preferably 0.4 to 0.6 mm.

[0124] The diameter of the inner bracket body 71 is not particularly limited, and for example, in the expanded state, the diameter is 10 to 25 mm and the length is 30 to 250 mm.

[0125] When the diameter of the digestive tract to be contacted is φ16 mm to φ20 mm, the pitch P1 of the end flared portions 72 is preferably set to be 12 mm or more.

[0126] If the diameter of the digestive tract to be contacted is about φ12 mm, the pitch P2 of the inner stent body 71 is preferably set to 3 mm or more.

[0127] The inner stent body 71 of the inner stent 6 is formed with a diameter slightly larger (for example, about 10 to 20% larger) than the diameter of the target digestive tract. When the inner stent 6 is placed inside the digestive tract, the inner stent 6 is placed inside the target digestive tract in a reduced diameter state, and then expanded after placement.

[0128] For example, when the inner stent 6 is placed in a digestive tract having a diameter of φ16 mm, the diameter of the inner stent body 71 of the placed inner stent 6 is preferably formed to be, for example, 17 to 32 mm in diameter in a natural state. In addition, in the end flared portion 72 of the placed inner stent 6, 3 to 11 peaks 721 are preferably arranged continuously in the circumferential direction, and the length L of one side 721a of the two sides 721a, 721a constituting the peak 721 is preferably formed to be 16 to 22 mm. In addition, in the end flared portion 72, in a natural state, the angle of the two sides 721a, 721a constituting the peak 721 is preferably formed to be, for example, 38.5 to 147.3°, and after the inner stent 6 is placed in the digestive tract, the angle of the two sides 721a, 721a constituting the peak 721 is preferably, for example, 36.2 to 78.4°.

[0129] Here, refer to Figure 6 to Figure 8 The results of an evaluation test in the case of using the inner bracket 6 of the present embodiment will be described.

[0130] In this evaluation test, a polydioxanone (PDO) monofilament yarn having a fiber diameter of 0.4 mm or 0.5 mm was used, and various parameters (number of peaks, pitch P1, tip angle θ, side length L) were changed to produce a stent consisting of an inner stent body 71 and an end flared portion 72 disposed at one end. Figure 5 The inner bracket 6 shown. At the end of the inner bracket 6, a plurality of peaks 721 are continuously arranged in the circumferential direction to form an end flared portion 72.

[0131] For example, in this evaluation test, fibers with a fiber diameter of 0.4 mm were used to prepare a 16 mm diameter intestinal tract. Figure 6 The inner support 6 has the parameters (the number of peaks, the pitch P1, the tip angle θ, and the length L of one side) shown in (a).

[0132] Here, since the inner stent 6 has a reduced diameter when placed in the intestinal tract, the inner stent 6 attached to a mandrel of 20 mm in diameter was manufactured, and the manufactured inner stent 6 was placed in the intestinal tract of 16 mm in diameter.

[0133] For example, Figure 6 As shown in the table on the upper side of (a), when the number of mountain portions is 3 and the pitch P1 of the end flared portion 72 in the retention state is 7.0 mm, 8.7 mm, 11.0 mm, 11.8 mm, 13.5 mm, 16.3 mm, 19.0 mm, and 22.0 mm, when the inner bracket 6 is mounted on a core rod of φ20 mm, for example, it is necessary to produce it with a pitch P1 smaller than the pitch P1 in the retention state, such as Figure 6 As shown in (b), for example, the pitch P1 is 3.0 mm, 6.0 mm, 9.0 mm, 10.0 mm, 12.0 mm, 15.0 mm, 18.0 mm, and 21.0 mm.

[0134] In addition, if Figure 6 As shown in the table below (a), when manufacturing a biodegradable stent having four peaks and a pitch P1 of the end flared portion 72 in the indwelling state of 5.6 mm, 7.7 mm, 10.1 mm, 11.0 mm, 12.8 mm, 15.7 mm, 18.7 mm, and 21.5 mm, when each stent is mounted on a φ20 mm mandrel, for example, it is necessary to manufacture the stent with a pitch P1 smaller than the pitch P1 in the indwelling state, as shown in FIG. Figure 6 As shown in (b), for example, the pitch P1 is 3.0 mm, 6.0 mm, 9.0 mm, 10.0 mm, 12.0 mm, 15.0 mm, 18.0 mm, and 21.0 mm.

[0135] In this case, if Figure 6 As shown in (a) and (b), the theoretical value of the "tip angle" can be calculated based on the pitch P1 and the number of peaks. It should be noted that the length of one side is the same whether it is in a left-behind state or when it is installed on a mandrel and manufactured.

[0136] As described above, in this evaluation test, when the inner stent 6 is made using fibers having a fiber diameter of 0.4 mm, the parameters (the number of peaks, spacing P1, front angle θ, and length of one side L) of the stent mounted on a mandrel of φ20 mm are calculated so as to become the values ​​(theoretical values) of the parameters (the number of peaks, spacing P1, front angle θ, and length of one side L) of the stent in a state of being indwelled in an intestinal tract of φ16 mm. Then, the inner stent 6 before indwelling is manufactured by mounting the fibers on a mandrel of φ20 mm so as to become the values ​​(theoretical values) of the parameters (the number of peaks, spacing P1, front angle θ, and length of one side L) of the stent in a state of being mounted on a mandrel of φ20 mm.

[0137] In this evaluation test, the following test was carried out using the stent produced in this manner.

[0138] As a test method, the inner stent 6 manufactured by changing various parameters (number of hills, pitch P1, front end angle θ, length of one side L) was placed in a polyethylene tube with an inner diameter of 16 mm or 20 mm, and a motion simulating peristalsis was applied to the polyethylene tube. For the inner stent 6 placed in the digestive tract, the motion simulating peristalsis of moving the polyethylene tube in one direction and returning was repeated 10 times, and the positional deviation of the stent from the initial position was measured.

[0139] The following instructions Figure 7 and Figure 8 Evaluation results shown.

[0140] Figure 7 and Figure 8 The evaluation results shown are obtained by using a fiber with a fiber diameter of φ0.4 mm or φ0.5 mm, and when the number of the peaks 721 of the end flared portion 72 is 3 or 4, making an inner bracket 6 by changing the length L of one side 721a of the two sides 721a, 721a of the end flared portion 72 and the front end angle θ, and measuring the distance of the positional migration of the end flared portion 72 after being placed using the made inner bracket 6, and the results are shown in the table. It should be noted that Figure 7 and Figure 8 The value of the blank portion in is not actually measured, but is estimated based on the measured value around the blank portion.

[0141] First, explain Figure 7 Evaluation results shown.

[0142] Figure 7 Evaluation result 1 shown is an evaluation result when fibers having a fiber diameter of φ0.4 mm are used.

[0143] like Figure 7 As shown in (a), when the number of the peaks is 3, the length L1 of one side 721a of the peak 721 of the end flared portion 72 is in the range of 14.5 mm to 23.5 mm and the front end angle θ formed by the two sides 721a constituting the peak 721 is in the range of 46.4 to 78.4°, the positional deviation of the inner bracket 6 after retention is less than 1 cm.

[0144] Therefore, the following evaluation results are obtained: when the number of peaks 721 is 3, the length L1 of one side 721a of the peak 721 of the end flare portion 72 is preferably in the range of 14.5 mm to 23.5 mm, and the front end angle θ formed by the sides 721a, 721a constituting the peak 721 is less than 78.4°.

[0145] In addition, if Figure 7 As shown in (b), when the number of the peaks is 4, the length L1 of one side 721a of the peak 721 of the end flared portion 72 is in the range of 16.9 mm to 22.4 mm and the front end angle θ formed by the two sides 721a constituting the peak 721 is in the range of 36.2 to 61.4°, the positional deviation of the inner bracket 6 after retention is less than 1 cm.

[0146] Therefore, the following evaluation results are obtained: when the number of peaks is 4, the length L1 of one side 721a of the peak 721 of the end flare portion 72 is preferably in the range of 16.9 mm to 22.4 mm, and the front end angle θ formed by the sides 721a, 721a constituting the peak 721 is less than 61.4°.

[0147] Next, explain Figure 8 Evaluation results 2 are shown.

[0148] Figure 8 Evaluation result 2 shown is an evaluation result when fibers having a fiber diameter of φ0.5 mm were used.

[0149] like Figure 8 As shown in (a), when the number of the peaks is 3, the length L1 of one side 721a of the peak 721 of the end flared portion 72 is in the range of 18.3 mm to 23.5 mm and the front end angle θ formed by the two sides 721a constituting the peak 721 is in the range of 46.4 to 67.1°, the positional deviation of the inner bracket 6 after retention is less than 1 cm.

[0150] Therefore, the following evaluation results are obtained: when the number of peaks is 3, the length L1 of one side 721a of the peak 721 of the end flare portion 72 is preferably in the range of 18.3 mm to 23.5 mm, and the front end angle θ formed by the two sides 721a, 721a constituting the peak 721 is less than 67.1°.

[0151] In addition, if Figure 8 As shown in (b), when the number of the peaks is 4, the length L1 of one side 721a of the peak 721 of the end flared portion 72 is in the range of 12.7 mm to 22.4 mm and the front end angle θ formed by the two sides 721a constituting the peak 721 is in the range of 36.2 to 65.9°, the positional deviation of the inner bracket 6 after retention is less than 1 cm.

[0152] Therefore, the following evaluation results are obtained: when the number of peaks is 3, the length L1 of one side 721a of the peak 721 of the end flare portion 72 is preferably in the range of 12.7 mm to 22.4 mm, and the front end angle θ formed by the sides 721a, 721a constituting the peak 721 is less than 65.9°.

[0153] In the above evaluation result 2, since the evaluation result that the front end angle θ formed by the two sides 721a, 721a of the mountain portion 721 of the end flared portion 72 is preferably 78.4 or less, it is preferably 80 degrees or less, for example. In addition, since the evaluation result that the side length L of one side 721a of the two sides 721a, 721a constituting the mountain portion 721 of the end flared portion 72 is preferably in the range of 16.9 to 22.4 mm, it is preferably in the range of 16 to 22 mm, for example.

[0154] According to the inner bracket 6 of the present embodiment described above, the following effects are achieved.

[0155] (2a) The inner stent 6 is formed by an end trumpet portion 72 disposed at the end in the axial direction, and a plurality of peak portions 721 formed by a front end corner portion protruding outward in the axial direction are continuously disposed in the circumferential direction, so that the end trumpet portion 72 is formed into a ring shape when viewed in the axial direction. When the inner stent 6 is indwelled in the digestive tract, the front end angle θ formed by two sides 721a, 721a constituting the peak portion 721 is set to be less than 80°, and the number of the plurality of peak portions 721 is set to 3 to 11. Thus, as shown in the results of the evaluation test, since the positional deviation of the inner stent 6 after indwelling relative to the peristaltic movement of the digestive tract is less than 1 cm, the tracking property relative to the peristaltic movement of the digestive tract can be exerted, and the positional deviation of the inner stent 6 after indwelling relative to the peristaltic movement of the digestive tract can be suppressed.

[0156] (2b) The two sides 611a and 611a of the end lattice 611 disposed at the end in the axial direction constitute the two sides 721a and 721a of the mountain portion 721 constituting the end trumpet portion 72. Thus, since the end lattice 611 is formed in a lattice shape and has compressive strength, the compressive strength of the mountain portion 721 is enhanced. Therefore, the positional deviation of the inner stent 6 after indwelling can be further suppressed with respect to the peristaltic movement of the digestive tract while the compressive strength is ensured at the end trumpet portion 72.

[0157] (2c) The inner stent 6 has a plurality of lattices 61 arranged in the axial direction, and the end lattices 611 are arranged at the ends of the plurality of lattices 61. Thus, the compression strength of the inner stent 6 as a whole can be ensured, and the positional deviation of the inner stent 6 after placement can be further suppressed at the end flared portion 72 relative to the peristaltic movement of the digestive tract.

[0158] (2d) The length of one side 721a of the two sides 721a, 721a constituting the mountain portion 721 is 16 to 22 mm. Therefore, as shown in the results of the evaluation test, since the positional deviation of the inner stent 6 after placement relative to the peristaltic movement of the digestive tract is less than 1 cm, the tracking property relative to the peristaltic movement of the digestive tract can be exerted, and the positional deviation of the inner stent 6 after placement relative to the peristaltic movement of the digestive tract can be further suppressed.

[0159] (2e) The adjacent peaks 721 in the end flared portion 72 are fixed to each other at the intersection on the axial end side. Thus, the positional deviation of the inner stent 6 after placement can be further suppressed relative to the peristaltic movement of the digestive tract while the compression strength is ensured in the end flared portion 72.

[0160] It should be noted that, in the inner stent 6, for example, in the present embodiment, the number of the mountain portions 721 of the synthetic resin stent 6 is formed to be 3 or 4, but it is not limited thereto. The number of the mountain portions 721 of the synthetic resin stent 6 is preferably 3 to 8 when the synthetic resin stent 6 is applied to a small intestine stent, and preferably 3 to 11 when the synthetic resin stent 6 is applied to an esophagus stent.

[0161] Next, the outer bracket 11 will be described. Fig. 9 It is a perspective view showing the outer bracket 11 according to the second embodiment. Fig.10 yes Fig. 9 An enlarged view of the outer bracket 11 is shown.

[0162] The outer support 11 of this embodiment is a biodegradable support made of biodegradable fibers, such as Fig. 9 and Fig.10 As shown, the mesh-like cylindrical portion 12 (first knitted component) and the wavy knitted portion 13 (second knitted component) knitted and arranged on the mesh-like cylindrical portion 12 are provided.

[0163] The mesh-like cylindrical portion 12 is woven into a mesh shape by a plurality of fibers 120 and is formed into a cylindrical shape, and has a plurality of diamond-shaped pores formed by the fibers 120 and arranged in an orderly manner on the outer periphery. The meshes of the mesh-like cylindrical portion 12 become sparse in the axial direction when the outer bracket 11 is in a state of shrinking diameter, and become dense in the axial direction when the outer bracket 11 is in an expanded diameter.

[0164] In this embodiment, if Fig.10As shown, the plurality of fibers 120 constituting the mesh-like cylindrical portion 12 are composed of a plurality of first fibers 121 and a plurality of second fibers 122. When viewed from the side, the mesh-like cylindrical portion 12 has a plurality of rhombus-shaped pores formed by the first fibers 121 and the second fibers 122, and has a plurality of first intersections 123 formed by the intersection of the plurality of first fibers 121 and the plurality of second fibers 122.

[0165] The plurality of first fibers 121 are formed by synthetic resin fibers extending at a predetermined angle relative to the axial direction. Fig.10 As shown, the plurality of first fibers 121 are arranged to extend obliquely from the upper right side to the lower left side.

[0166] The plurality of second fibers 122 are formed of synthetic resin fibers that cross and extend with respect to the plurality of first fibers 121. Fig.10 As shown, the plurality of second fibers 122 are arranged to extend obliquely from the upper left side to the lower right side.

[0167] The material of the first fiber 121 and the second fiber 122 is not particularly limited, and preferably a material rich in rigidity. For example, if a biodegradable resin is used, homopolymers, copolymers, and blended polymers composed of L-lactic acid, D-lactic acid, DL-lactic acid, glycolic acid, ε-caprolactone, and p-dioxanone can be cited. It should be noted that even if it is a non-biodegradable resin, as long as it is a material rich in rigidity. In particular, as the material of the fiber constituting the first fiber 121 and the second fiber 122, for example, polylactic acid (PLA) and poly-L-lactic acid (PLLA) are preferably used. In the present embodiment, the first fiber 121 and the second fiber 122 are formed, for example, using polylactic acid (PLA).

[0168] When a biodegradable fiber is used as the fiber 120, its diameter is preferably 0.1 to 0.4 mm. When the diameter of the biodegradable fiber 120 is less than 0.1 mm, there is a tendency for the strength of the outer stent 11 to decrease. When the diameter of the biodegradable fiber 120 exceeds 0.4 mm, since the diameter in the reduced diameter state becomes larger, there is a tendency for it to be difficult to accommodate the outer stent 11 in a thin tubular member such as a delivery system. From the viewpoint of being accommodated in a delivery system with a thinner inner diameter, the upper limit of the diameter of the biodegradable fiber 120 is more preferably 0.3 mm. From the viewpoint of maintaining a higher strength, the lower limit of the diameter of the biodegradable fiber 120 is more preferably 0.2 mm. In the present embodiment, as the fiber 120, biodegradable fibers with diameters of 0.2 mm and 0.3 mm are used.

[0169] like Fig. 9As shown, the wavy braided portion 13 is composed of a plurality of fibers 130 in an annular wave shape woven and arranged on the mesh-like cylindrical portion 12. In the present embodiment, the plurality of fibers 130 constituting the wavy braided portion 13 are composed of a plurality of third fibers 131 disposed separately in the axial direction and a plurality of fourth fibers 132 disposed separately in the axial direction. The wavy braided portion 13 has a plurality of second intersections 133 formed by the plurality of third fibers 131 and the plurality of fourth fibers 132 intersecting.

[0170] like Fig.10 As shown, the peaks and valleys of the third fibers 131 and the fourth fibers 132 are alternately continuous and form a wave shape extending in the circumferential direction of the mesh-like cylindrical portion 12. The third fibers 131 and the fourth fibers 132 are arranged so that their convex portions face each other and partially overlap.

[0171] More specifically, the third fiber 131 and the fourth fiber 132 are both formed into a wave shape having a mountain portion that is convex to the first direction D1 side and a mountain portion that is convex to the second direction D2 side, and when viewed from the side, the mountain portions of each other are partially overlapped and arranged, and cross at two second intersections 133. In addition, when viewed from the side, the wavy woven portion 13 has an intersection region 134. The intersection region 134 is a portion where the convex portions of the third fiber 131 and the fourth fiber 132 overlap each other, and is an area surrounded by the third fiber 131 and the fourth fiber 132 between two second intersections 133 that are adjacently arranged among the plurality of second intersections 133. A plurality of intersection regions 134 are arranged and formed in the circumferential direction of the tubular mesh-like cylindrical portion 12.

[0172] The material of the synthetic resin fiber constituting the third fiber 131 and the fourth fiber 132 is not particularly limited, and a material with high recovery is preferred. For example, if a biodegradable resin is used, homopolymers, copolymers, and blended polymers composed of L-lactic acid, D-lactic acid, DL-lactic acid, glycolic acid, ε-caprolactone, and p-dioxanone can be cited. It should be noted that even non-biodegradable resins can be used as long as they are a material with high recovery. As the material of the third fiber 131 and the fourth fiber 132, for example, polydioxanone (PDO) is preferably used.

[0173] When biodegradable fibers are used as the fibers 130 , the diameter thereof is preferably 0.1 to 0.4 mm. In the present embodiment, biodegradable fibers having a diameter of 0.15 to 0.22 mm are used as the fibers 130 .

[0174] When the mesh-like cylindrical portion 12 is viewed from the side, the first intersections 123 of the mesh-like cylindrical portion 12 are respectively arranged in a plurality of intersection regions 134 of the wavy woven portion 13. The first intersections 123 are arranged in a plurality of intersection regions 134, and a plurality of first intersections 123 are arranged and formed in the circumferential direction of the cylindrical mesh-like cylindrical portion 12. The portion where the first intersections 123 of the mesh-like cylindrical portion 12 are arranged in the intersection regions 134 of the wavy woven portion 13 constitutes the first hooking portion 141. The outer bracket 11 of the present embodiment includes a plurality of first hooking portions 141, and a row of the plurality of first hooking portions 141 arranged in the circumferential direction is formed over the entire region in the axial direction.

[0175] In the first hooking portion 141, the third fiber 131 is arranged in a state where the third fiber 131 can be hooked on one or more of the first fiber 121, the second fiber 122, and the fourth fiber 132 in response to movement in a direction in which the portion in which the convex portions of the third fiber 131 and the fourth fiber 132 overlap each other becomes smaller. In addition, the fourth fiber 132 is arranged in a state where the fourth fiber 132 can be hooked on one or more of the first fiber 121, the second fiber 122, and the third fiber 131 in response to movement in a direction in which the portion in which the convex portions of the third fiber 131 and the fourth fiber 132 overlap each other becomes smaller.

[0176] In the present embodiment, the third fiber 131 and the fourth fiber 132 constituting the wavy woven portion 13 are formed of synthetic resin fibers having a higher expansion force than the first fiber 121 and the second fiber 122 constituting the mesh-like cylindrical portion 12, and have a property that the bent portion wants to return to a straight line. At least a portion of the third fiber 131 and the fourth fiber 132 are woven and arranged in the mesh-like cylindrical portion 12, and can act in a direction to expand the diameter of the outer bracket 11, and can deform the mesh-like cylindrical portion 12 from a state of reduced diameter to a state of expanded diameter.

[0177] The structure of the first hooking portion 141 is described below. It should be noted that: Fig.10 is along with Fig.10 Configuration in the direction perpendicular to the paper (the direction across the paper) Fig. 9 Therefore, the inner side of the outer bracket 11 in the radial direction is Fig.10 The inner side in the vertical direction of the paper, the outer side in the radial direction of the outer bracket 11 is Fig.10 The near front side in the direction perpendicular to the paper.

[0178] like Fig.10 As shown, in the first hooking portion 141 , the first fibers 121 and the second fibers 122 of the mesh-like cylindrical portion 12 cross in an X shape at the first intersection 123 .

[0179] The third fiber 131 is arranged at any of the two second intersection points 133 relative to the fourth fiber 132. Fig.10 Thus, the third fibers 131 and the fourth fibers 132 of the outer stent 11 are arranged so as not to be hooked with each other when moving toward the first direction D1 or the second direction D2.

[0180] In the wavy weave portion 13 , where the convex portions of the third fibers 131 and the fourth fibers 132 overlap, first intersection points 123 of the first fibers 121 and the second fibers 122 are arranged in intersection regions 134 surrounded by the third fibers 131 and the fourth fibers 132 .

[0181] like Fig.10 As shown, the first fiber 121 is arranged to extend obliquely from the upper right side to the lower left side in the intersection region 134. The first fiber 121 passes through the front side of one of the third fiber 131 and the fourth fiber 132 from the upper right side to the lower left side, crosses the second fiber 122 at the first intersection 123, and passes through the back side of the other of the third fiber 131 and the fourth fiber 132.

[0182] like Fig.10 As shown, the second fiber 122 is arranged to extend obliquely from the upper left side to the lower right side in the intersection region 134. The second fiber 122 passes through the near front side of one of the third fiber 131 and the fourth fiber 132, crosses the first fiber 121 at the first intersection point 123, and passes through the back side of the other of the third fiber 131 and the fourth fiber 132.

[0183] By configuring the first fiber 121, the second fiber 122, the third fiber 131, and the fourth fiber 132 in the above manner, in the first hooking portion 141, the fiber on the side of the third fiber 131 and the fourth fiber 132 that is convex toward the mountain portion on the first direction D1 is configured in the following state: it can be hooked on the first fiber 121 and the second fiber 122 with respect to movement in the direction in which the overlapping portion of the convex portions of the third fiber 131 and the fourth fiber 132 becomes smaller, and the fiber on the other side of the third fiber 131 and the fourth fiber 132 that is convex toward the mountain portion on the second direction D2 side opposite to the first direction D1 is configured in the following state: it can be hooked on the first fiber 121 and the second fiber 122 with respect to movement in the direction in which the overlapping portion of the convex portions of the third fiber 131 and the fourth fiber 132 becomes smaller.

[0184] When manufacturing the outer bracket 11 described above, the outer bracket 11 can be manufactured by weaving the wavy braided portion 13 and then weaving the mesh-like cylindrical portion 12, or conversely, by first weaving the mesh-like cylindrical portion 12 and then weaving the wavy braided portion 13. When manufacturing the outer bracket 11, for example, a cylindrical jig having a plurality of pins erected at predetermined intervals on the circumference can be used to weave the wavy braided portion 13 while hooking fibers on the plurality of pins, and then passing the fibers of the mesh-like cylindrical portion 12 through the intersection region of the wavy braided portion 13, thereby manufacturing the outer bracket 11.

[0185] Since the outer stent 11 configured as described above is woven into a cylindrical shape by the first fibers 121 and the second fibers 122 tilted with respect to the axial direction in the mesh-like cylindrical portion 12 , the shape of the stent is maintained in a cylindrical shape.

[0186] In addition, a wavy woven portion 13 is woven on the mesh-like cylindrical portion 12. The wavy woven portion 13 (third fiber 131 and fourth fiber 132) is formed of synthetic resin fibers having a higher expansion force than the mesh-like cylindrical portion 12 (first fiber 121 and second fiber 122), and has a property that the bent portion wants to return to a straight line. Therefore, by weaving the wavy woven portion 13 in a wavy shape in a manner that surrounds the circumference of the mesh-like cylindrical portion 12, the wavy woven portion 13 can be used to apply force in the direction of expanding the diameter of the outer stent 11, thereby increasing the expansion force.

[0187] Therefore, the radial expansion force of the outer stent 11 can be strengthened, and the self-expandability can be exhibited. In addition, the adhesion to the wall of the digestive tract is improved, and the ability to follow the movement of the digestive tract can be exhibited.

[0188] The outer bracket 11 is formed into a cylindrical shape extending in the longitudinal direction X (predetermined direction) by weaving fibers made of synthetic resin. The outer bracket 11 is arranged to cover the outer periphery of the portion on the central side of the inner bracket 6 in the longitudinal direction X. The outer bracket 11 is formed of fibers made of synthetic resin having a finer diameter than the inner bracket 6 so as to have a denser mesh than the inner bracket 6. The outer bracket 11 can be deformed from a state of reduced diameter to a state of expanded diameter.

[0189] When the biodegradable stent 10 is placed in the digestive tract, first, the outer stent 11 is placed in the digestive tract in a state of reduced diameter, and then expanded in diameter after placement. Thus, the outer stent 11 is placed in the digestive tract with an expanded diameter. Thereafter, the inner stent 6 is placed inside the outer stent 11 in a state of reduced diameter, and then expanded in diameter after placement. Thus, the inner stent 6 and the outer stent 11 are placed in an overlapping manner in a state in which the center side of the inner stent 6 is arranged inside the outer stent 11.

[0190] According to the outer bracket 11 of the second embodiment described above, the following effects are achieved.

[0191] (3a) The outer support 11 includes a mesh-like cylindrical portion 12 and a wavy braided portion 13. The mesh-like cylindrical portion 12 is a cylindrical mesh-like cylindrical portion formed of a plurality of fibers 121 and 122 woven into a mesh shape. The wavy braided portion 13 is woven and arranged on the mesh-like cylindrical portion 12 and is formed in an annular shape and is formed of a plurality of fibers 131 and 132. The mesh-like cylindrical portion 12 is formed to have a plurality of first fibers 121 extending at a predetermined angle with respect to the axial direction, and the first fibers 121 and 122 are connected to each other. The wavy woven portion 13 is constructed by a plurality of second fibers 122 that cross and extend along the fiber 121 and a plurality of first intersection points 123 that are formed by the intersection of a plurality of first fibers 121 and a plurality of second fibers 122, and a plurality of third fibers 131 that are wavy in shape and are arranged separately in the axial direction and a plurality of fourth fibers 132 that are wavy in shape and are arranged separately in the axial direction, and at least one first intersection point 123 is arranged in an intersection area 134 surrounded by the third fibers 131 and the fourth fibers 132.

[0192] Thus, since the mesh-like cylindrical portion 12 of the outer stent 11 is woven into a cylindrical shape by the first fiber 121 and the second fiber 122 inclined relative to the axial direction, the shape of the stent is maintained in a cylindrical shape. In addition, by weaving a wavy woven portion 13 in a wavy shape in the mesh-like cylindrical portion 12, and configuring the first intersection 123 of the mesh-like cylindrical portion 12 in the intersection area 134 of the wavy woven portion 13, the wavy woven portion 13 can be used to exert a force in the direction of expanding the diameter, thereby increasing the radial expansion force. Therefore, the radial expansion force of the outer stent 11 can be strengthened, and the self-expandability can be exerted. In addition, the close contact with the wall of the digestive tract becomes higher, and the tracking property of the movement to the digestive tract can be exerted. Therefore, it can be set as a stent that ensures the storage property of a tubular component such as a delivery system, and at the same time, it is difficult to cause positional deviation after the stent is left in the affected part in the biological duct.

[0193] (3b) A plurality of intersection regions 134 are arranged and formed in the circumferential direction of the cylindrical mesh-like cylindrical portion 12, and a plurality of first intersection points 123 are arranged and formed in the circumferential direction of the cylindrical mesh-like cylindrical portion 12, and the plurality of first intersection points 123 are respectively arranged in the plurality of intersection regions 134. Thus, since the wavy braided portion 13 can be braided in the circumferential direction, the radial expansion force of the outer stent 11 can be further strengthened.

[0194] (3c) In the structure in which the first intersection 123 of the mesh-like cylindrical portion 12 is arranged at the intersection region 134 of the wavy woven portion 13, the third fiber 131 is arranged in a state in which the third fiber 131 can be hooked on one or more of the first fiber 121, the second fiber 122, and the fourth fiber 132 with respect to movement in a direction in which the overlapped portion of the third fiber 131 and the fourth fiber 132 becomes smaller, and the fourth fiber 132 is arranged in a state in which the fourth fiber 132 can be hooked on one or more of the first fiber 121, the second fiber 122, and the third fiber 131 with respect to movement in a direction in which the overlapped portion of the third fiber 131 and the fourth fiber 132 becomes smaller. Thus, the first intersection 123 can be prevented from shifting by hooking the third fiber 131 and the fourth fiber 132 of the wavy woven portion 13 on any fiber.

[0195] (3d) The wavy woven portion 13 (third fibers 131 and fourth fibers 132) is formed of synthetic resin fibers having a higher expansion force than the mesh-like cylindrical portion 12 (first fibers 121 and second fibers 122). Thus, since the tubular mesh-like cylindrical portion 12 formed of the first fibers 121 and second fibers 122 is formed, and the first fibers 121 and second fibers 122 can be expanded in the radial direction by the third fibers 131 and fourth fibers 132, the expansion force in the radial direction can be further increased.

[0196] Furthermore, according to the biodegradable stent 10 of the second embodiment described above, similarly to the effect of (1a) of the first embodiment, the following effect (4a) is achieved.

[0197] (4a) The biodegradable stent 10 is constituted by an inner stent 6 and an outer stent 11, wherein the inner stent 6 has an inner stent body 71 formed of synthetic resin fibers and having a mesh and being able to be deformed from a reduced diameter state to an expanded diameter state, and the outer stent 11 is formed in a tubular shape having a mesh denser than that of the inner stent body 71 and is arranged to cover the outer periphery of the inner stent body 71 and is able to be deformed from a reduced diameter state to an expanded diameter state. Therefore, by arranging the inner stent body 71 having a sparse mesh inside the outer stent 11 having a dense mesh, the strength of the outer stent 11 can be enhanced by the pressing force of the inner stent body 71 from the inner side of the outer stent 11, thereby ensuring the strength of the biodegradable stent 10 as a whole. Thus, since the digestive tract can be pressed in a state where the strength of the biodegradable stent 10 as a whole is ensured by the pressing force of the inner stent body 71 from the inner side of the outer stent 11, stenosis can be prevented and the movement of the biodegradable stent 10 can be prevented. Therefore, it is possible to realize a biodegradable stent 10 that can exhibit self-expandability, restorability, adhesion to the digestive tract, and ability to follow peristaltic motion.

[0198] <First Variation of Second Embodiment>

[0199] Next, an outer bracket 11A according to a first modified form of the second embodiment will be described. Fig.11 It is a diagram showing an outer bracket 11A according to a first modified form of the second embodiment.

[0200] like Fig.11 As shown, the outer bracket 11A of the first modified form of the second embodiment has a first hook portion 141 ( Fig.11 The left side of the figure) and the second hook portion 142 ( Fig.11 The plurality of first hooking portions 141 and the plurality of second hooking portions 142 of the outer bracket 11A are alternately arranged in a spiral shape in the circumferential direction.

[0201] because Fig.11 The structure of the first hook portion 141 shown is the same as the structure of the first hook portion 141 described in the second embodiment, and therefore the description thereof will be omitted.

[0202] The structure of the second hook portion 142 will be described below.

[0203] like Fig.11 As shown, in the second hooking portion 142 , similarly to the first hooking portion 141 of the second embodiment, the first fibers 121 and the second fibers 122 of the mesh-like cylindrical portion 12 cross in an X-shape at the first intersection 123 .

[0204] In the second hooking portion 142, the third fiber 131 is located at one of the two second intersection points 133 ( Fig.11 The left side of the figure) is arranged near the front side of the fourth fiber 132, and the second intersection 133 ( Fig.11 The third fiber 131 and the fourth fiber 132 are arranged on the inner side of the fourth fiber 132. Thus, the third fiber 131 and the fourth fiber 132 are arranged in a state where they can be hooked with each other with respect to movement in a direction in which the overlapped portion of the convex portions of the third fiber 131 and the fourth fiber 132 becomes smaller.

[0205] Furthermore, the first intersection points 123 of the first fibers 121 and the second fibers 122 are arranged in the intersection region 134 surrounded by the third fibers 131 and the fourth fibers 132 of the wavy weave portion 13 .

[0206] like Fig.11 As shown, the first fiber 121 is configured to extend obliquely from the upper right side to the lower left side in the intersection area 134, passes through the inner side of the fourth fiber 132 from the upper right side to the lower left side, intersects with the second fiber 122 at the first intersection point 123, and passes through the inner side of the third fiber 131.

[0207] like Fig.11 As shown, the second fiber 122 is arranged to extend obliquely from the upper left side to the lower right side in the intersection area 134, passes through the inner side of the fourth fiber 132 from the upper left side to the lower right side, intersects with the first fiber 121 at the first intersection point 123, and passes through the inner side of the third fiber 131.

[0208] That is, in the second hooking portion 142 , the first fiber 121 and the second fiber 122 are entirely arranged behind the third fiber 131 and the fourth fiber 132 , so that the third fiber 131 and the fourth fiber 132 are entirely arranged in front of the first fiber 121 and the second fiber 122 .

[0209] By configuring the first fiber 121, the second fiber 122, the third fiber 131 and the fourth fiber 132 in the above manner, in the second hooking portion 142, the third fiber 131 and the fourth fiber 132 are configured in the following state: with respect to the movement in the direction in which the overlapping portion of the convex portions of the third fiber 131 and the fourth fiber 132 becomes smaller, the third fiber 131 and the fourth fiber 132 are configured as a whole on the near front side of the first fiber 121 and the second fiber 122, and the third fiber 131 and the fourth fiber 132 are configured in the following state: with respect to the movement of the third fiber 131 and the fourth fiber 132 toward the first direction D1 side or the second direction D2 side, the third fiber 131 and the fourth fiber 132 are not hooked on the first fiber 121 and the second fiber 122.

[0210] According to the outer bracket 11A of the first modified form of the second embodiment described above, in addition to the effects (3a) to (3d) described above, the following effects are achieved.

[0211] (3e) A structure in which a plurality of first intersection points 123 of the mesh-shaped cylindrical portion 12 are arranged at the intersection region 134 of the wavy woven portion 13, and a structure in which the third fiber 131 and the fourth fiber 132 are arranged in a state in which they can hook each other with respect to movement in a direction in which the overlapped portion of the third fiber 131 and the fourth fiber 132 becomes smaller, and in which they are not hooked on the first fiber 121 and the second fiber 122 with respect to movement of the third fiber 131 and the fourth fiber 132. Thus, by arranging the third fiber 131 and / or the fourth fiber 132 in a state in which they are not hooked on the first fiber 121 and the second fiber 122, it is difficult to restrict the length in the axial direction when the outer stent 11A is extended, and thus the storage property in the delivery system can be improved.

[0212] <Second Variation of Second Embodiment>

[0213] Next, an outer bracket 11B according to a second modified form of the second embodiment will be described. Fig.12It is a diagram showing an outer bracket 11B according to a second modified form of the second embodiment.

[0214] Compared with the outer bracket 11 of the second embodiment, the outer bracket 11B of the second modified mode of the second embodiment is arranged in a row formed by circumferentially arranging a plurality of first hooking portions 141 in the wavy woven portion 13 (second woven constituent portion) woven in the mesh-shaped cylindrical portion 12 (first woven constituent portion), not closely arranged in the axial direction of the outer bracket 11A, but separately arranged at a certain interval.

[0215] like Fig.12 As shown, the wavy braided portion 13 is configured to have a row in which a plurality of first hooking portions 141 are arranged in the circumferential direction and a row in which the first hooking portions 141 are not formed in the axial direction of the mesh-shaped cylindrical portion 12 having a plurality of first intersections 123. In the row in which a plurality of first hooking portions 141 are arranged in the circumferential direction, the first intersections 123 are arranged in the intersection regions 134 of the wavy braided portion 13 at the first hooking portions 141. In the row in which the first hooking portions 141 are not formed, a plurality of first intersections 123 are arranged in the circumferential direction.

[0216] According to the outer bracket 11B of the second modified form of the second embodiment described above, in addition to the effects (3a) to (3e) described above, the following effects are achieved.

[0217] (3f) A plurality of first hooking portions 141 are arranged in a row arranged in the circumferential direction and separated by a certain interval in the axial direction. Thus, by providing a row without the first hooking portion 141 in a part of the axial direction instead of being arranged closely in the axial direction of the outer stent 11B, when the outer stent 11B is extended, the axial length is less likely to be limited by the third fiber 131 and the fourth fiber 132, thereby improving the storage property in the delivery system.

[0218] <Third Variation of Second Embodiment>

[0219] An outer bracket 11C according to a third modified form of the second embodiment will be described below. Fig.13 It is a diagram showing an outer bracket 11C according to a third modified form of the second embodiment.

[0220] like Fig.13 As shown, in the outer bracket 11C of the third modified form of the second embodiment, a plurality of loops 135 are formed at the top of the mountain portion in the wavy fourth fiber 132. The loop 135 is arranged in a structure in which the first intersection 123 of the mesh-like cylindrical portion 12 is arranged in the intersection area 134 of the wavy braided portion 13, and is formed in a ring shape surrounding the first fiber 121, the second fiber 122, the third fiber 131, and the fourth fiber 132.

[0221] It should be noted that the plurality of loop portions 135 may be continuously disposed at the top of the mountain portion in the wavy fourth fiber 132, or may be intermittently disposed at the top of the plurality of mountain portions in the wavy fourth fiber 132. In addition, the loop portion 135 may not be configured to surround all of the first fiber 121, the second fiber 122, the third fiber 131, and the fourth fiber 132, but may be configured to surround only a portion of the first fiber 121, the second fiber 122, the third fiber 131, and the fourth fiber 132.

[0222] According to the outer bracket 11C of the third modified form of the second embodiment described above, in addition to the effects (3a) to (3f) described above, the following effects are achieved.

[0223] (3g) A ring portion 135 is provided at the top of the mountain portion of the wavy third fiber 131 and / or the fourth fiber 132. Here, for example, when there is no ring portion 135 at the top of the mountain portion of the wavy braided portion 13, since only the expansion force in the radial direction acts, it is difficult for the wavy third fiber 131 and the fourth fiber 132 in the wavy braided portion 13 to control the size of the diameter of the outer stent 11C. In contrast, in the present invention, since the ring portion 135 can exert a contraction force in the radial direction, the size of the diameter of the outer stent 11C can be controlled.

[0224] <Fourth Variation of Second Embodiment>

[0225] Reference Fig.14 and Fig.15 An outer bracket 110 according to a fourth modified form of the second embodiment will be described. Fig.14 It is a perspective view showing an outer bracket 110 according to a fourth modified form of the second embodiment of the present invention. Fig.15 yes Fig.14 The enlarged view of the outer bracket 110 is shown in FIG. Fig.15 In the outer bracket 110, one side in the axial direction is referred to as the first direction D1, and the other side in the axial direction is referred to as the second direction D2. In the outer bracket 110, one side in the circumferential direction is referred to as the third direction D3 ( Fig.15 The other side in the circumferential direction is referred to as the fourth direction D4 ( Fig.15 on the right side of the screen).

[0226] The synthetic resin stent of this embodiment is an outer stent 110 composed of biodegradable fibers, such as Fig.14 and Fig.15 As shown, the first zigzag knitted portion 200 (first knitted component) and the second zigzag knitted portion 300 (second knitted component) knitted and arranged on the first zigzag knitted portion 200 are provided.

[0227] The first folded braided portion 200 is formed into a mesh shape, and a plurality of fibers extending in the axial direction are arranged in a circumferential direction and formed into a cylindrical shape. Fig.15 As shown, the fibers 220 constituting the first meander-like weave portion 200 are composed of a plurality of first fibers 221 and a plurality of second fibers 222 .

[0228] The plurality of first fibers 221 are formed of synthetic resin fibers that are inclined at a predetermined angle with respect to the axial direction and repeatedly bend in the axial direction. The plurality of first fibers 221 repeatedly bend in the axial direction so as to reciprocate within a predetermined width in the circumferential direction of the first zigzag braided portion 200 and extend in the axial direction.

[0229] The plurality of second fibers 222 are formed of synthetic resin fibers that are repeatedly and reciprocatingly bent and extend in the axial direction, and are arranged to have a portion intersecting with the plurality of first fibers 221. The plurality of second fibers 222 are repeatedly and reciprocatingly bent and extend in the axial direction within a predetermined width in the circumferential direction of the first folded braided portion 200.

[0230] In the present embodiment, the plurality of first fibers 221 and the plurality of second fibers 222 are formed by one fiber, and the upper and lower ends in the axial direction of the first zigzag woven portion 200 are folded back and formed. The plurality of first fibers 221 and the plurality of second fibers 222 are part of one fiber. In other words, the first fibers 221 and the second fibers 222 are alternately arranged in the circumferential direction of the first zigzag woven portion 200. It should be noted that the first zigzag woven portion 200 may also be formed by a plurality of fibers.

[0231] More specifically, if Fig.15 As shown, the first fiber 221 and the second fiber 222 are each formed with a plurality of bends, and the plurality of bends have a mountain portion that is convex toward the third direction D3 side and a mountain portion that is convex toward the fourth direction D4 side. When viewed from the side, the first fiber 221 and the second fiber 222 are arranged in a manner that the bends overlap each other and cross in the first intersection region 223. In the first intersection region 223, the first fiber 221 and the second fiber 222 are formed with a substantially rhombus-shaped opening in the region surrounded by the first fiber 221 and the second fiber 222.

[0232] In the first intersection region 223, the first fiber 221 and the second fiber 222 may be arranged so as to overlap when viewed from the side, and may or may not be hooked with each other. In the present embodiment, the first fiber 221 and the second fiber 222 are hooked at the bent portions of the upper and lower ends of the outer bracket 110 in the axial direction, and are not hooked at the bent portions of the outer bracket 110 except for the upper and lower ends in the axial direction. The first intersection region 223 is arranged in the axial and circumferential directions of the first folded braided portion 200.

[0233] It should be noted that the area surrounded by the first fiber 221 and the second fiber 222 is opened to form the first intersection area 223. However, the size of the opening of the first intersection area 223 is not limited thereto. In addition, the first fiber 221 and the second fiber 222 may be hooked with each other by pulling in a direction in which the overlapped portion of the first fiber 221 and the second fiber 222 becomes smaller, so that the area surrounded by the first fiber 221 and the second fiber 222 of the first intersection area 223 is not opened.

[0234] The material of the first fiber 221 and the second fiber 222 is not particularly limited, and preferably has a material rich in rigidity. For example, if a biodegradable resin is adopted, homopolymers, copolymers, and blended polymers composed of L-lactic acid, D-lactic acid, DL-lactic acid, glycolic acid, ε-caprolactone, and p-dioxanone can be cited. It should be noted that even if it is a non-biodegradable resin, as long as it is a material rich in rigidity. In particular, as the material of the fiber constituting the first fiber 221 and the second fiber 222, for example, polylactic acid (PLA) and poly-L-lactic acid (PLLA) are preferably used. In the present embodiment, the first fiber 221 and the second fiber 222 are formed, for example, using polylactic acid (PLA).

[0235] When a biodegradable fiber is used as the fiber 220, its diameter is preferably 0.1 to 0.4 mm. When the diameter of the biodegradable fiber 220 is less than 0.1 mm, there is a tendency for the strength of the outer stent 110 to decrease. When the diameter of the biodegradable fiber 20 exceeds 0.4 mm, since the diameter in the reduced diameter state becomes larger, there is a tendency for it to be difficult to accommodate the outer stent 110 in a thin tubular member such as a delivery system. From the viewpoint of being accommodated in a delivery system with a thinner inner diameter, the upper limit of the diameter of the biodegradable fiber 20 is more preferably 0.3 mm. From the viewpoint of maintaining a higher strength, the lower limit of the diameter of the biodegradable fiber 220 is more preferably 0.2 mm. In the present embodiment, as the fiber 220, biodegradable fibers with diameters of 0.2 mm and 0.3 mm are used.

[0236] like Fig.14 and Fig.15As shown, in the second zigzag braided portion 300, a plurality of fibers extending in the circumferential direction and forming a ring shape by repeatedly bending the fibers 230 are arranged in the axial direction and braided in the first zigzag braided portion 200. Fig.15 As shown, the fibers 230 constituting the second meander-like weave portion 300 are composed of a plurality of third fibers 231 and a plurality of fourth fibers 232 .

[0237] The third fibers 231 are formed of synthetic resin fibers that are inclined at a predetermined angle with respect to the axial direction and repeatedly bend in the circumferential direction. The third fibers 231 repeatedly bend in the circumferential direction to reciprocate within a predetermined width in the axial direction of the second zigzag braided portion 300.

[0238] The plurality of fourth fibers 232 are formed of synthetic resin fibers that are repeatedly bent and extend in the circumferential direction and are arranged to have a portion intersecting with the plurality of third fibers 231. The plurality of fourth fibers 232 are repeatedly bent and extend in the circumferential direction in a manner that reciprocates within a predetermined width in the axial direction of the second zigzag braided portion 300.

[0239] More specifically, the third fiber 231 and the fourth fiber 232 are each formed with a plurality of bends, and the plurality of bends have a mountain portion that is convex to the first direction D1 side and a mountain portion that is convex to the second direction D2 side. When viewed from the side, the third fiber 231 and the fourth fiber 232 are arranged in a manner that the bends overlap each other, and cross in the second intersection area 233. In the second intersection area 233, the third fiber 231 and the fourth fiber 232 can be arranged in a manner that overlaps when viewed from the side, and can be hooked to each other or not. In this embodiment, the bends of the third fiber 231 and the fourth fiber 232 are hooked to each other in the second intersection area 233, and the area surrounded by the third fiber 231 and the fourth fiber 232 is not open. The second intersection area 233 is arranged in the axial direction and circumferential direction of the second folded woven portion 300.

[0240] It should be noted that the third fibers 231 and the fourth fibers 232 are hooked at their bent portions, and in the second intersection region 233, the region surrounded by the third fibers 231 and the fourth fibers 232 is not open, but the present invention is not limited thereto. The region of the second intersection region 233 surrounded by the third fibers 231 and the fourth fibers 232 may be open, and the size of the opening of the second intersection region 233 is not limited.

[0241] The third fibers 231 or the fourth fibers 232 disposed at the upper end or the lower end of the outer bracket 110 among the plurality of third fibers 231 and the plurality of fourth fibers 232 are wound around the first fibers 221 or the second fibers 222 of the first meandering braided portion 200 .

[0242] The material of the synthetic resin fiber constituting the third fiber 231 and the fourth fiber 232 is not particularly limited, and a material with high recovery is preferred. For example, if a biodegradable resin is used, homopolymers, copolymers, and blended polymers composed of L-lactic acid, D-lactic acid, DL-lactic acid, glycolic acid, ε-caprolactone, and p-dioxanone can be cited. It should be noted that even if it is a non-biodegradable resin, it can be used as long as it is a material with high recovery. As the material of the third fiber 231 and the fourth fiber 232, for example, polydioxanone (PDO) is preferably used.

[0243] When biodegradable fibers are used as the fibers 230 , the diameter thereof is preferably 0.1 to 0.4 mm. In the present embodiment, biodegradable fibers having a diameter of 0.15 to 0.22 mm are used as the fibers 230 .

[0244] When the outer stent 110 is viewed from the side, at least a portion of the first intersection region 223 of the first folded braided portion 200 and the second intersection region 233 of the second folded braided portion 300 are overlapped. The portion where at least a portion of the second intersection region 233 of the second folded braided portion 300 and the second intersection region 233 of the first folded braided portion 200 are overlapped constitutes a hook portion 241. The outer stent 110 of the present embodiment includes a plurality of hook portions 241, and a row of the plurality of hook portions 241 arranged in the circumferential direction is formed over the entire region in the axial direction.

[0245] The structure of the hook portion 241 is described below. It should be noted that: Fig.15 is along with Fig.15 Configuration in the direction perpendicular to the paper (the direction across the paper) Fig.14 Therefore, the inner side of the outer bracket 110 in the radial direction is Fig.15 The inner side in the vertical direction of the paper, the outer side in the radial direction of the outer bracket 110 is Fig.15 In addition, there are also portions woven in such a manner that the fibers do not unravel at the upper and lower ends of the outer bracket 110 in the axial direction. Here, in the description of the hook portion 241 in this embodiment, the portion excluding the upper and lower ends of the outer bracket 110 in the axial direction is described.

[0246] like Fig.15 As shown, in the hook portion 241 , a second intersection region 233 of the third fibers 231 and the fourth fibers 232 is arranged in the first intersection region 223 surrounded by the first fibers 221 and the second fibers 222 .

[0247] In the first intersection region 223 arranged in the hook portion 241 , the first fibers 221 and the second fibers 222 of the first meandering weave portion 200 are arranged with openings so as to overlap with each other with their bends convex in the third direction D3 and in the fourth direction D4 .

[0248] In the second intersection region 233 arranged in the hooking portion 241 , the third fibers 231 and the fourth fibers 232 of the second zigzag weave portion 300 are arranged with the zigzag portions convex in the first direction D1 and convex in the second direction D2 hooked to each other.

[0249] In the hook portion 241, as Fig.15 As shown, the bends of the first fibers 221 and the second fibers 222 of the first meander-shaped braided portion 200 that are convex toward the third direction D3 side pass through the inner side of the third fibers 231 and the fourth fibers 232 at the apex side of the convexity (the third direction D3 side), and pass through the front side of the third fibers 231 and the fourth fibers 232 at the open side of the convexity (the fourth direction D4 side). In addition, the bends of the first fibers 221 and the second fibers 222 that are convex toward the fourth direction D4 side pass through the front side of the third fibers 231 and the fourth fibers 232 at the apex side of the convexity (the fourth direction D4 side), and pass through the front side of the third fibers 231 and the fourth fibers 232 at the open side of the convexity (the third direction D3 side). The bends of the first fibers 221 and the second fibers 222 that are convex toward the third direction D3 side pass through the front side of the bends that are convex toward the fourth direction D4 side.

[0250] By configuring the first fiber 221, the second fiber 222, the third fiber 231 and the fourth fiber 232 in the above manner, in the hooking portion 241, the first fiber 221 is configured in the following state: the first fiber 221 can be hooked on the third fiber 231 and the fourth fiber 232 with respect to movement in the direction in which the overlapping portion of the convex portions of the first fiber 221 and the second fiber 222 becomes smaller, and the second fiber 222 is configured in the following state: the second fiber 222 can be hooked on the third fiber 231 and the fourth fiber 232 with respect to movement in the direction in which the overlapping portion of the convex portions of the first fiber 221 and the second fiber 222 becomes smaller.

[0251] When manufacturing the outer bracket 110 described above, the second zigzag braided portion 300 may be formed and then the first zigzag braided portion 200 may be formed, or conversely, the first zigzag braided portion 200 may be formed first and then the second zigzag braided portion 300 may be formed.

[0252] Since the outer stent 110 configured as described above is formed into a cylindrical shape by the first fibers 221 and the second fibers 222 extending in the axial direction while being inclined with respect to the axial direction and repeatedly bent in the first meander-shaped braided portion 200 , the shape of the stent is maintained in a cylindrical shape.

[0253] In addition, the second folded braided portion 300 is woven into the first folded braided portion 200. The second folded braided portion 300 (third fiber 231 and fourth fiber 232) is formed of synthetic resin fibers having a higher expansion force than the first folded braided portion 200 (first fiber 221 and second fiber 222), and has a property that the bent portion wants to return to a straight line. Therefore, by repeatedly folding and weaving the second folded braided portion 300 in a manner of going around the circumference of the first folded braided portion 200, the second folded braided portion 300 can be used to apply force in a direction to expand the diameter of the outer stent 110, thereby increasing the expansion force.

[0254] Therefore, the radial expansion force of the outer stent 110 can be strengthened, and the self-expandability can be exhibited. In addition, the adhesion to the wall of the digestive tract is improved, and the ability to follow the movement of the digestive tract can be exhibited.

[0255] According to the outer bracket 110 of the fourth modified form of the second embodiment described above, the following effects are achieved.

[0256] (4a) The outer support 110 is formed by a first folded woven portion 200 having a tubular shape and formed of one or more fibers and configured in a mesh shape, and a second folded woven portion 300 having one or more fibers and configured in an annular shape and woven and arranged on the first folded woven portion 200, wherein the first folded woven portion 200 is configured to have a plurality of first fibers 221 extending in the axial direction at a predetermined angle and repeatedly folded, a plurality of second fibers 222 extending in the axial direction at a predetermined angle and repeatedly folded and arranged to have a portion intersecting the first fibers 221, and a plurality of first fibers 221 extending in the axial direction at a predetermined angle and repeatedly folded. The second folded woven portion 300 is constructed to have a plurality of first intersection areas 223 formed by the intersection of a plurality of fibers 221 and a plurality of second fibers 222, the second folded woven portion 300 is constructed to have a plurality of third fibers 231 extending circumferentially in a manner inclined at a predetermined angle relative to the axial direction and repeatedly folded, a plurality of fourth fibers 232 arranged with portions intersecting the third fibers 231 and extending axially in a manner inclined at a predetermined angle relative to the axial direction and repeatedly folded, and a plurality of second intersection areas 233 formed by the intersection of the plurality of third fibers 231 and the plurality of fourth fibers 232, and the first intersection areas 223 and the second intersection areas 233 are constructed to be at least partially overlapped.

[0257] Thus, since the first folded braided portion 200 of the outer stent 110 is formed into a cylindrical shape by the first fiber 221 and the second fiber 222 extending in the axial direction at a predetermined angle and repeatedly folded relative to the axial direction, the shape of the stent is maintained in a cylindrical shape. In addition, by weaving the second folded braided portion 300 in the first folded braided portion 200, and configuring the first intersection area 223 of the first folded braided portion 200 and the second intersection area 233 of the second folded braided portion 300 to overlap at least a part, the second folded braided portion 300 can be used to apply force in the direction of expanding the diameter, and the radial expansion force can be increased. Therefore, the radial expansion force of the outer stent 110 can be strengthened, and the self-expandability can be exerted. In addition, the close contact with the wall of the digestive tract becomes higher, and the tracking property of the movement to the digestive tract can be exerted. Therefore, it can be set as a stent that ensures the storage property of a tubular member such as a delivery system, and is difficult to cause positional deviation after the stent is left in the affected part in the biological duct.

[0258] (4b) In the structure in which the first intersection region 223 of the first zigzag knitted portion 200 and the second intersection region 233 of the second zigzag knitted portion 300 are overlapped, the first fiber 221 is arranged in a state in which the first fiber 221 can be hooked on one or more fibers of the third fiber 231 and the fourth fiber 232 with respect to movement in the direction in which the overlapped portion of the first fiber 221 and the second fiber 222 becomes smaller, and the second fiber 222 is arranged in a state in which the second fiber 222 can be hooked on one or more fibers of the third fiber 231 and the fourth fiber 232 with respect to movement in the direction in which the overlapped portion of the first fiber 221 and the second fiber 222 becomes smaller. Thus, the first intersection region 223 and the second intersection region 233 can be prevented from shifting by hooking the first fiber 221 and the second fiber 222 of the first zigzag knitted portion 200 on any of the third fiber 231 and the fourth fiber 232.

[0259] Hereinafter, production examples and working examples of biodegradable stents according to the first to third modified embodiments of the second embodiment described above will be briefly described.

[0260] In this manufacturing example, the outer bracket 11A of the first modified form of the second embodiment (see Fig.11 ) and the outer bracket 11B of the second modified form of the second embodiment (refer to Fig.12 ), the number of braids using the combination of PLA fibers was set to 6 (3 with a fiber diameter of 0.2 mm, and 3 with a fiber diameter of 0.3 mm), and the wavy PDO fiber was made with a fiber diameter of 0.15 to 0.22 mm.

[0261] In addition, regarding the outer bracket 11C of the third modified form of the second embodiment (see Fig.13 ), the number of braids of the combination of PLA fibers is set to 6 (fiber diameter is 0.2 mm), the wave-shaped fiber diameter of PDO fibers is 0.30 to 0.349 mm, and the ring-shaped fiber diameter is 0.15 to 0.22 mm.

[0262] In the above outer stents 11A, 11B, and 11C, PLA fibers are woven in a tangled manner around PDO fibers woven in a wave shape, so that the shape of the stent is less likely to be crushed.

[0263] By manufacturing the outer stents 11A, 11B, and 11C under the above conditions, a stent that can be accommodated in a delivery system (φ2.8 mm) for the small intestine can be realized. In addition, since the diameter of the delivery system becomes larger when used in other digestive tracts, the fiber diameter can also be thickened, thereby expecting the manufacture of a stent with higher strength. In addition, the fiber diameter, the diameter and length of the stent are arbitrary.

[0264] The following experiment was conducted using the outer brackets 11A and 11C manufactured in this manner.

[0265] Using a jig made by our company that reproduces peristaltic motion, we conducted a stent movement test. The jig used this time simulated peristaltic motion by placing a stent in a tube simulating the intestine, and assuming that the intestine would shrink to φ10mm due to peristalsis, the tube was pulled 10 times with a jig with a hole diameter of 10mm to simulate peristaltic motion.

[0266] In the intestinal model in which the intestinal diameter during peristaltic movement was set to φ17 mm when expanded and φ10 mm when contracted, the outer stent 11A (stent length 55 mm) of the second embodiment moved 35 mm.

[0267] In the intestinal model in which the intestinal diameter during peristaltic motion is set to φ12mm when expanding and φ10mm when contracting, the outer stent 11C (stent length 36mm) of the third variant of the second embodiment moves 10mm. The fact that the metal stent (stent length 110mm) moves 40mm in the same intestinal model suggests that the outer stents 11A and 11C of the first and third variants of the second embodiment have the ability to follow the intestine.

[0268] A preferred embodiment of the synthetic resin bracket of the present invention has been described above, but the present invention is not limited to the above-described embodiment and can be modified appropriately.

[0269] For example, in the above-mentioned embodiment, a biodegradable stent made of biodegradable fibers is used as the synthetic resin stent, but the present invention is not limited thereto. That is, the stent may be made of synthetic resin fibers that are not biodegradable.

[0270] In addition, in the second embodiment, a plurality of first hooking parts 141 are provided on the entire outer stent 11. In addition, in the third variation of the second embodiment, the first hooking parts 141 and the second hooking parts 142 are provided alternately. In addition, in the second variation of the second embodiment, a plurality of first hooking parts 141 are arranged in a circumferential direction. However, the present invention is not limited to the above embodiment, and the first hooking part 141 and / or the second hooking part 142 may not be provided on the entire biodegradable stent, but may be provided on a part of the biodegradable stent.

[0271] In the second embodiment, the loop portion 135 is provided at the top of the mountain portion in the wavy fourth fiber 132 , but the present invention is not limited thereto and the loop portion 135 may be provided at the top of the mountain portion in the wavy third fiber 131 .

[0272] A preferred embodiment of the synthetic resin stent and the stent delivery system of the present invention has been described above, but the present invention is not limited to the above-described embodiment and can be modified appropriately.

[0273] For example, in the above-mentioned embodiment, a biodegradable stent made of biodegradable fibers is used as the synthetic resin stent, but the present invention is not limited thereto. That is, the stent may be made of synthetic resin fibers that are not biodegradable.

[0274] In addition, in the first embodiment, the biodegradable stent 1 is formed by combining the inner stent 2 and the outer stent 5, and in the second embodiment, the biodegradable stent 10 is formed by combining the inner stent 6 and the outer stent 11, but the present invention is not limited thereto. The biodegradable stent may be formed by combining the inner stent 2 of the first embodiment and the outer stent 11 of the second embodiment, and the biodegradable stent may be formed by combining the inner stent 6 of the second embodiment and the outer stent 5 of the first embodiment.

[0275] Description of Reference Numerals

[0276] 1.10 Biodegradable stent (synthetic resin stent)

[0277] 2 Inner bracket (first bracket)

[0278] 3 Inner bracket body (first bracket body)

[0279] 4 End flare (end enlarged diameter)

[0280] 5 Outer bracket (second bracket)

[0281] 6 Inner bracket (first bracket)

[0282] 11, 11A, 11B, 11C, 110 Outer bracket (second bracket)

[0283] 32 cylindrical connection part (connection part)

[0284] 311 Polygonal ring

[0285] 200 First zigzag knitting portion (first knitting component)

[0286] 300 Second zigzag knitting portion (second knitting component)

[0287] 221 First Fiber

[0288] 222 Second Fiber

[0289] 223 First Intersection Area

[0290] 231 Third Fiber

[0291] 232 Fourth Fiber

[0292] 233 Second intersection area

[0293] 241 Hooking part

Claims

1. A synthetic resin bracket having: a first stent having a first stent body portion formed of synthetic resin fibers in a tubular shape having meshes and capable of being deformed from a state of reduced diameter to a state of expanded diameter; and a second bracket, the second bracket being formed into a cylindrical shape having a mesh denser than that of the first bracket main body and being arranged so as to cover the outer periphery of the first bracket main body, the second bracket being capable of deforming from a state of reduced diameter to a state of expanded diameter, A plurality of polygonal ring-shaped portions formed of synthetic resin fibers into polygonal rings are arranged and connected in the longitudinal direction of the first stent in a state where they are bent or curved so as to be convex along the longitudinal direction of the first stent, thereby forming the first stent main body. The polygonal annular portion includes a pair of bent portions bent to be convex toward one side in the longitudinal direction and a pair of bent portions bent to be convex toward the other side in the longitudinal direction. The plurality of polygonal annular portions are arranged and connected in the length direction by connecting the mutually facing bent portions of the adjacent polygonal annular portions with each other using a tubular connecting portion in a state where the bent portions of the adjacent polygonal annular portions are arranged to face each other. A pair of adjacent polygonal annular portions have their protrusions of synthetic resin fibers connected to each other at the tubular connecting portion that connects the pair of bending portions to each other, and a pair of adjacent polygonal annular portions have their protrusions of synthetic resin fibers connected to each other at the tubular connecting portion that connects the pair of bending portions to each other.

2. The synthetic resin bracket according to claim 1, wherein: The first stent further includes an end portion with an expanded diameter, the end portion with an expanded diameter connected to at least one end portion in the longitudinal direction of the first stent main body and having a larger diameter than the first stent main body.

3. The synthetic resin bracket according to claim 2, wherein: The end enlarged diameter portion is formed of synthetic resin fibers having a smaller diameter than the first stent main body portion and having a polygonal annular structure having more sides than the polygonal annular portion.

4. The synthetic resin bracket according to claim 1, wherein: The first bracket is a bracket having an end flared portion disposed at an end in the axial direction and formed of a wire. The end flared portion is formed into a ring shape when viewed in the axial direction by continuously arranging a plurality of peak portions consisting of front end corner portions protruding outward in the axial direction in the circumferential direction. When the stent is placed in the digestive tract, the angle formed by the two sides constituting the mountain portion is less than 80°. The number of the plurality of mountain portions is 3 to 11.

5. The synthetic resin bracket according to claim 4, wherein: The two sides constituting the mountain portion are constituted by two sides of an end lattice disposed at the end in the axial direction.

6. The synthetic resin bracket according to claim 5, wherein: The first bracket has a plurality of grids arranged in an axial direction. The end grid is arranged at an end of the plurality of grids.

7. The synthetic resin bracket according to any one of claims 4 to 6, wherein: The length of one side of the two sides constituting the mountain portion is 16 to 22 mm.

8. The synthetic resin bracket according to claim 4, wherein: The adjacent peak portions in the end flared portion are fixed to each other at an intersection point on the endmost side in the axial direction.

9. The synthetic resin bracket according to claim 1, wherein: The second stent is a synthetic resin stent having a first woven component and a second woven component, wherein the first woven component is a tubular woven component woven into a mesh shape and formed of a plurality of fibers, and the second woven component is woven and arranged on the first woven component and is formed into a ring shape and formed of a plurality of fibers. The first braided component includes a plurality of first fibers extending at a predetermined angle inclined relative to the axial direction, a plurality of second fibers extending and crossing the first fibers, and a plurality of first intersections formed by the intersection of the plurality of first fibers and the plurality of second fibers. The second braided component includes a plurality of third fibers in a wave shape that are arranged separately in the axial direction and a plurality of fourth fibers in a wave shape that are arranged separately in the axial direction. At least one first intersection point among the plurality of first intersection points is disposed in an intersection region surrounded by the third fiber and the fourth fiber.

10. The synthetic resin bracket according to claim 9, wherein: The intersection regions are arranged in a circumferential direction of the first knitted component and are formed in plurality. A plurality of the first intersection points are arranged in a circumferential direction of the first knitted component, and the plurality of the first intersection points are respectively arranged in the plurality of intersection regions.

11. The synthetic resin bracket according to claim 9 or 10, wherein: In a structure in which the first intersection point is arranged in the intersection area, The third fiber is arranged in a state that the third fiber can be hooked on one or more of the first fiber, the second fiber, and the fourth fiber in response to movement in a direction in which the overlapped portion of the third fiber and the fourth fiber becomes smaller. The fourth fiber is disposed in a state where the fourth fiber can be hooked on one or more of the first fiber, the second fiber, and the third fiber in response to movement in a direction in which the overlapped portion between the third fiber and the fourth fiber becomes smaller.

12. The synthetic resin bracket according to claim 11, wherein: There are a plurality of structures for arranging the first intersection points in the intersection areas, At least a portion of the synthetic resin support includes the following structure, in which the third fiber and the fourth fiber are arranged in the following state: they can hook each other in response to movement in the direction in which the overlapping portion of the third fiber and the fourth fiber becomes smaller, and they are not hooked on the first fiber and the second fiber in response to the movement of the third fiber and the fourth fiber.

13. The synthetic resin bracket according to claim 9, wherein: At the top of the mountain portion in the wavy third fiber and / or the fourth fiber, an annular ring portion is formed so as to surround any one or more of the first fiber, the second fiber, the third fiber, and the fourth fiber.

14. The synthetic resin bracket according to claim 9, wherein: The second braided component part is formed of synthetic resin fibers having a higher expansion force than the first braided component part.

15. The synthetic resin bracket according to claim 1, wherein: The second stent is a synthetic resin stent having a first woven component and a second woven component, wherein the first woven component is a tubular woven component that is mesh-shaped and formed of one or more fibers, and the second woven component is woven and arranged on the first woven component and is annular and formed of one or more fibers. The first braided component comprises a plurality of first fibers extending in the axial direction at a predetermined angle and repeatedly bending with respect to the axial direction, a plurality of second fibers extending in the axial direction at a predetermined angle and repeatedly bending with respect to the axial direction and arranged to have a portion intersecting with the first fibers, and a plurality of first intersection regions formed by the intersection of the plurality of first fibers and the plurality of second fibers. The second braided component comprises a plurality of third fibers extending in the circumferential direction at a predetermined angle inclined relative to the axial direction and repeatedly bending, a plurality of fourth fibers extending in the axial direction at a predetermined angle inclined relative to the axial direction and repeatedly bending so as to have a portion intersecting with the third fibers, and a plurality of second intersection regions formed by the intersection of the plurality of third fibers and the plurality of fourth fibers. At least a portion of the first intersection region and the second intersection region are overlapped.

16. The synthetic resin bracket according to claim 15, wherein: In a structure where the first intersection region and the second intersection region are arranged overlappingly, The first fiber is arranged in a state that the first fiber can be hooked on one or more of the third fiber and the fourth fiber in response to movement in a direction in which the overlapped portion of the first fiber and the second fiber becomes smaller, The second fiber is arranged in a state where the second fiber can be hooked on one or more of the third fiber and the fourth fiber in response to movement in a direction in which the overlapped portion of the first fiber and the second fiber becomes smaller.

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