Method for manufacturing a cover stent and cover stent

Abstract

A method for manufacturing a covered stent that includes: placing an inner cover (3) inside a stent body with a mesh structure formed by weaving wires, said stent body having an interlocking part (2b) in which two bends of the wires are interlocked to each other; placing an outer cover (4) outside the stent body; forming a slack section (6), which expands in the radial direction of the stent body, in at least one of the covers (3, 4), said slack section (6) providing a slack that allows the two bends to move in the longitudinal and radial directions of the stent body to at least one of the covers (3, 4); and joining the covers (3, 4) together in the inner region of the mesh of the mesh structure.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a covered stent and a covered stent.

Background Art

[0002] Conventionally, covered stents that are placed in a stenotic portion of a lumen to relieve stenosis have been known (see, for example, Patent Documents 1 and 2). A covered stent includes a cover that covers at least one of the inside and outside of a tubular stent body. Infiltration of tissue into the inside of the stent placed in the lumen is prevented by the cover.

[0003] In the covered stent of Patent Document 1, an inner cover and an outer cover are adhered to each other at the mesh portions of the mesh-shaped stent body. Thereby, twisting of the cover during expansion of the stent body is prevented, and the inner and outer covers can also bend together with the stent body. The covered stent of Patent Document 2 has a plurality of adhesive portions where the inner cover and the outer cover are adhered to each other, which are formed at intervals from each other, and pockets that allow movement of the stent body are formed between adjacent adhesive portions. Thereby, the covered stent can be radially compressed with a small force.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The stent is desired to be easily curved along the shape of the lumen without applying a load to the tube wall, and for this purpose, it is required that the axial force of the stent be low. The axial force is the force with which the curved stent tries to return to a straight shape. A stent body having an engaging portion in which two bent portions of a wire are intertwined with each other realizes high flexibility and low axial force due to the three-dimensional relative displacement of the two bent portions during bending. In the case of the cover stents of Patent Documents 1 and 2, since the cover inhibits the three-dimensional displacement of the two bent portions, the flexibility is reduced and the axial force is increased as compared with the case without the cover.

[0006] The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a method for manufacturing a cover stent and a cover stent that can achieve a low axial force.

Means for Solving the Problems

[0007] One aspect of the present invention is a method for manufacturing a cover stent, including disposing an inner cover inside a stent body having a mesh structure formed by braiding a wire, the stent body having an engaging portion in which two bent portions of the wire are hooked on each other; disposing an outer cover outside the stent body; forming a slack portion that bulges in the radial direction of the stent body in at least one of the inner cover and the outer cover, the slack portion imparting a slack that allows movement of the two bent portions in the longitudinal direction and the radial direction of the stent body to the at least one of the inner cover and the outer cover; and joining the inner cover and the outer cover to each other in a region inside the mesh of the mesh structure.

[0008] Another aspect of the present invention is a stent body having a mesh structure formed by braiding wires, the stent body having an engaging portion in which two bent portions of the wires are engaged with each other, an inner cover covering the inside of the stent body, and an outer cover covering the outside of the stent body, at least one of the inner cover and the outer cover having a slack portion that bulges in the radial direction of the stent body, the slack portion imparting slack to at least one of the inner cover and the outer cover that allows movement of the two bent portions in the longitudinal direction and the radial direction of the stent body, and the inner cover and the outer cover being joined to each other in a region inside the mesh of the mesh structure, which is a covered stent.

[0009] Another aspect of the present invention is a method for manufacturing a covered stent, in which a cover made of ePTFE is arranged on at least one of the inside and the outside of a stent body in a direction in which the stretching direction of the ePTFE coincides with the stretching direction of the stent body when the cover is radially contracted, the cover is partially connected to the stent body, and the cover is stretched by radially contracting the stent body to generate slack in the cover.

[0010] Another aspect of the present invention is a covered stent including a stent body and a cover made of ePTFE that covers at least one of the inside and the outside of the stent body and is partially connected to the stent body, the cover being arranged in a direction in which the stretching direction of the ePTFE coincides with the stretching direction of the stent body when the cover is radially contracted, and the cover having slack in the longitudinal direction of the stent body in a state where the stent body is expanded in the radial direction.

Advantages of the Invention

[0011] According to the present invention, there is an effect that a low axial force of the covered stent can be realized.

Brief Description of the Drawings

[0012]

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Mode for Carrying Out the Invention

[0013] (First Embodiment) A method for manufacturing a cover stent and the cover stent according to the first embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the cover stent 1 according to the present embodiment includes a tubular stent body 2, a tubular inner cover 3 that covers the inside of the stent body 2, and a tubular outer cover 4 that covers the outside of the stent body 2.

[0014] The stent body 2 is formed by zigzagging and knitting one or more wires 2a while winding around the central axis, and has a mesh structure in which a large number of rhombic meshes are arranged in the circumferential direction and the longitudinal direction. The stent body 2 is radially contractible. The cover stent 1 is mounted on a delivery system in a contracted state, carried into the body cavity by the delivery system, and radially expanded in the body cavity.

[0015] As shown in FIG. 2A, the stent body 2 has an engaging portion 2b where two bent portions 2c and 2d of the wire 2a are hooked to each other in the longitudinal direction of the stent body 2. One bent portion 2c is a ridge portion that bends toward one end of the stent body 2 and protrudes toward the other end. The other bent portion 2d is a valley portion that bends toward the other end of the stent body 2 and protrudes toward one end. The zigzag wire 2a has ridge portions 2c and valley portions 2d arranged alternately in the circumferential direction. The engaging portion 2b is formed by the engagement of the ridge portions 2c in one row with the valley portions 2d in the adjacent other row.

[0016] In this way, the two bent portions 2c and 2d are connected to be displaceable relative to each other in the longitudinal and radial directions. Due to the three-dimensional displacement of the bent portions 2c and 2d at the engaging portion 2b, the stent body 2 can be easily curved with little or no axial force generated.

[0017] The inner cover 3 and the outer cover 4 are sheets made of ePTFE (Expanded polytetrafluoroethylene). The materials of the covers 3 and 4 may be other materials having biocompatibility and flexibility, generally used for stents, such as silicone and the like. The inner cover 3 and the outer cover 4 are joined to each other at a joining portion 5 which is a part of the region inside the mesh, and are separated from each other at portions other than the joining portion 5.

[0018] As shown in FIG. 2B, the inner cover 3 has a plurality of slack portions 6 arranged at intervals in the longitudinal direction. Each slack portion 6 is a concave portion that extends over the entire circumference of the inner cover 3 and bulges radially inward, and has, for example, a U-groove shape with a rectangular cross-sectional shape in the longitudinal vertical cross-section. Some of the engaging portions 2b are arranged between the slack portions 6 and the outer cover 4.

[0019] The slack portion 6 forms a space between the inner cover 3 and the outer cover 4, and imparts slack to the inner cover 3. The inner cover 3 having slack can be deformed freely according to an external force, and allows movement of the pair of bent portions 2c and 2d forming the engaging portion 2b in the longitudinal direction and the radial direction. Therefore, the movable range of the bent portions 2c and 2d at the engaging portion 2b is increased, and it is prevented that the covers 3 and 4 obstruct the three-dimensional displacement of the bent portions 2c and 2d when the cover stent 1 is bent. Thereby, low axial force and high flexibility of the cover stent 1 are realized.

[0020] FIGS. 3 and 4 illustrate the relationship between the displacement of the bent portions 2c and 2d due to the bending of the cover stent 1 and the deformation of the covers 3 and 4 having slack. In FIGS. 3 and 4, the left figure is a front view of the stent body 2 inside the bend, the middle figure is a schematic view of the covers 3 and 4 inside and outside the bend, and the right figure is a schematic view of the wires 2a inside and outside the bend. In FIGS. 3 and 4, both the inner cover 3 and the outer cover 4 have slack.

[0021] When the cover stent 1 bends from the straight shape in FIG. 3 to the curved shape in FIG. 4, the vertices of the two bent portions 2c and 2d at the engaging portion 2b are displaced in the longitudinal direction in opposite directions to each other inside and outside the bend, and are displaced inward in the radial direction. At this time, the covers 3 and 4 having slack are deformed according to the displacement of the bent portions 2c and 2d inward in the longitudinal direction and the radial direction. Therefore, when the cover stent 1 bends, the two bent portions 2c and 2d can be displaced in the same manner as when the covers 3 and 4 do not exist, and low axial force can be realized.

[0022] Next, a method for manufacturing the cover stent according to the present embodiment will be described. As shown in Fig. 5, the method for manufacturing the cover stent includes step SA1 of arranging the inner cover 3 on the first jig 20, step SA2 of forming a slack portion 6 in the inner cover 3, step SA3 of arranging the inner cover 3 inside the stent body 2, step SA4 of arranging the outer cover 4 outside the stent body 2, step SA5 of joining the inner cover 3 and the outer cover 4 to each other, and step SA6 of removing the cover stent 1 from the jig 20.

[0023] As shown in Fig. 6, the jig 20 is a cylindrical mandrel, and a plurality of recesses 20a arranged at intervals in the longitudinal direction are formed on the outer surface of the mandrel 20. The plurality of recesses 20a are structures for forming the slack portion 6. Each recess 20a extends over the entire circumference and is recessed inward in the radial direction. A convex portion 20b is formed between adjacent recesses 20a. As shown in Fig. 7, the inner cover 3 is arranged on the outer surface of the mandrel 20 (step SA1). The form of the inner cover 3 is selected from a tube, a tape, and a sheet. In the case of a tape or a sheet, the inner cover 3 is arranged on the mandrel 20 after being pre-formed and joined into a tubular shape, or is wound around the mandrel 20 without a gap.

[0024] Next, the slack portion 6 is formed by pushing the inner cover 3 into the recess 20a using a pusher 30 (step SA2). The pusher 30 is, for example, a rod-shaped or ring-shaped member. By deforming the inner cover 3 along the inner surface of the recess 20a, the slack portion 6 having dimensions and a shape corresponding to the dimensions and shape of the recess 20a is formed. In order to surely deform the inner cover 3 along the inner surface of the recess 20a, the tip of the pusher 30 may have an outer surface shape complementary to the inner surface shape of the recess 20a. Next, by inserting the mandrel 20 into the stent body 2, the stent body 2 is arranged on the outer surface of the inner cover 3 (step SA3). The stent body 2 and the inner cover 3 are aligned with each other at a position where the engaging portion 2b is arranged in the slack portion 6.

[0025] Next, an outer cover 4 is disposed on the stent body 2, and the stent body 2 is covered by the outer cover 4 (step SA4). Similar to the inner cover 3, the form of the outer cover 4 is selected from among a tube, a tape, and a sheet. In the case of a tube, a mandrel 20 on which the inner cover 3 and the stent body 2 are disposed is inserted into the outer cover 4. In the case of a tape or a sheet, the mandrel 20 is inserted into the outer cover 4 preformed into a tube shape, or the outer cover 4 is wound around the mandrel 20 over the entire circumference.

[0026] Next, in a partial region inside the mesh of the stent body 2, the inner cover 3 and the outer cover 4 are joined by a method such as thermocompression bonding using a joining tool 40, thereby forming a joint portion 5 (step SA5). The region to be joined is the region inside the mesh on the convex portion 20b, and the joint portion 5 is formed between two engaging portions 2b disposed in two adjacent slack portions 6 (see FIG. 2A). Next, by removing the mandrel 20 from inside the inner cover 3, a covered stent 1 having slack portions 6 is manufactured (step SA6).

[0027] Thus, according to the manufacturing method of the present embodiment, the inner cover 3 has slack due to the slack portions 6, and the covers 3 and 4 can manufacture a covered stent 1 having a low axial force and high flexibility that do not prevent the bending of the stent body 2. Also, the movable range of the bent portions 2c and 2d depends on the dimensions of the slack portions 6. In step SA2, by inserting the inner cover 3 into the concave portion 20a of the mandrel 20, slack portions 6 having dimensions equivalent to those of the concave portion 20a are formed. Thereby, dimensions such as the depth and width of the slack portions 6 can be easily and accurately controlled to form slack portions 6 having desired dimensions, and the desired bending characteristics of the covered stent 1 can be surely achieved. Further, by varying the dimensions and shapes of the concave portions 20a for each position, slack portions 6 having different sizes and shapes for each position can be easily formed.

[0028] Excessive slack in the inner cover 3 causes an increase in the diameter of the cover stent 1 in the contracted state, thereby increasing the sliding resistance of the cover stent 1 against the delivery system and requiring a large operating force when releasing the cover stent 1 from the delivery system. Also, excessive slack in the inner cover 3 can reduce the volume of the hollow portion inside the cover stent 1 through which substances pass in the body cavity. Therefore, it is important to control the slack portion 6 to a desired dimension. According to the present embodiment, as described above, by using the mandrel 20 having the concave portion 20a, the dimension of the slack portion 6 can be easily and accurately controlled. Also, among the double covers 3, 4, only the inner cover 3 has the slack portion 6, and the outer cover 4 does not have a slack portion. Therefore, the sliding resistance when releasing the cover stent 1 from the delivery system can be reduced.

[0029] In the present embodiment, the slack portion 6 is U-groove-shaped with a flat bottom wall. However, the shape of the slack portion 6 is not limited to this and can be changed as appropriate. FIGS. 8A and 9A show other examples of the longitudinal cross-sectional shape of the slack portion 6. The slack portion 6 in FIG. 8A is substantially M-shaped and has two side walls parallel to the radial direction and a bent bottom wall protruding radially outward. The slack portion 6 in FIG. 9A is substantially V-shaped with two side walls forming an angle with each other, one side wall being parallel to the radial direction and the other side wall being inclined with respect to the radial direction. Such a slack portion 6 is formed by inserting the inner cover 3 into a substantially M-shaped or substantially V-shaped concave portion 20a. The tip of the pusher 30 may have a shape corresponding to the shape of the concave portion 20a.

[0030] FIGS. 8B and 9B show the slack portion 6 folded by the radial compressive force. In the case of the substantially M-shaped slack portion 6, the two side walls fall outward, and a part of the inner cover 3 constituting the slack portion 6 overlaps radially outside the opening of the slack portion 6. In the case of the substantially V-shaped slack portion 6, the two side walls fall in the same direction outward, and a part of the inner cover 3 constituting the slack portion 6 overlaps radially outside the opening of the slack portion 6. In this way, the substantially M-shaped and substantially V-shaped slack portions 6 are deformed into a predetermined folding shape by the radial compressive force. Therefore, when the cover stent 1 is mounted on the delivery system, the slack portion 6 can be folded into a predetermined shape simply by compressing the cover stent 1 in the radial direction.

[0031] The portion where a part of the inner cover 3 overlaps in the radial direction due to the folding of the slack portion 6 becomes thick (refer to the range indicated by the arrow in FIGS. 8B and 9B). Such a thick portion is preferably disposed at a position displaced from the engaging portion 2b where the two portions 2c and 2d of the wire 2a overlap in the radial direction. According to the slack portion 6 from FIGS. 8A to 9B, the folding shape of the slack portion 6 can be controlled so that the thick portion is disposed in a region where it does not interfere with the engaging portion 2b.

[0032] (Second Embodiment) Next, a manufacturing method of the cover stent and the cover stent according to the second embodiment of the present invention will be described. In the present embodiment, a configuration different from that of the first embodiment will be described, and the same reference numerals will be given to the configurations common to the first embodiment, and the description thereof will be omitted. The cover stent according to the present embodiment includes a stent body 2, an inner cover 3, and an outer cover 4. The cover stent of the present embodiment is different from the cover stent 1 of the first embodiment in that the inner cover 3 and the outer cover 4 each have slack portions 6 and 7 (see FIG. 11).

[0033] The outer cover 4 has a plurality of slack portions 7 arranged at intervals in the longitudinal direction of the outer cover 4 and formed at the same position as the slack portion 6. Each slack portion 7, similar to the slack portion 6, extends over the entire circumference of the outer cover 4 and is a concave portion that bulges radially inward, and for example, has a U-groove shape with a rectangular cross-sectional shape in the longitudinal vertical cross-section. Some engaging portions 2b are disposed between the slack portion 6 and the slack portion 7.

[0034] The outer cover 4 provided with slack by the slack portion 7 can be freely deformed according to an external force, similarly to the inner cover 3, and allows movement of the pair of bent portions 2c and 2d forming the engaging portion 2b in the longitudinal direction and the radial direction. Therefore, when the cover stent 1 is bent, it is prevented that the covers 3 and 4 interfere with the three-dimensional displacement of the bent portions 2c and 2d. Thereby, low axial force and high flexibility of the cover stent are realized.

[0035] As shown in FIG. 10, the manufacturing method of the cover stent according to the present embodiment includes a step SB1 of disposing the inner cover 3 on the jig 20, a step SB2 of disposing the inner cover 3 inside the stent body 2, a step SB3 of disposing the outer cover 4 outside the stent body 2, steps SB41 and SB42 of forming slack portions 6 and 7 in the inner cover 3 and the outer cover 4, a step SB5 of joining the inner cover 3 and the outer cover 4 to each other, and a step SB6 of removing the cover stent from the jig 20. The step of forming the slack portions 6 and 7 includes a step SB41 of forming the slack portion 6 in the inner cover 3 before the step SB3, and a step SB42 of forming the slack portion 7 in the outer cover 4 after the step SB3.

[0036] As shown in FIG. 11, similarly to the step SA1, the inner cover 3 is disposed on the outer surface of the mandrel 20 (step SB1). Next, similarly to the step SA2, by using the pusher 30 to push the inner cover 3 into the recess 20a, the slack portion 6 is formed (step SB41). Next, similarly to the step SA3, by inserting the mandrel 20 into the stent body 2, the stent body 2 is disposed on the outer surface of the inner cover 3 (step SB2).

[0037] Next, similarly to the step SA4, the outer cover 4 is disposed on the stent body 2, and the stent body 2 is covered with the outer cover 4 (step SB3). Next, by using the pusher 30 to push the outer cover 4 into the recess 20a, the slack portion 7 is formed (step SB42).

[0038] Next, in a partial region inside the mesh of the stent body 2, the inner cover 3 and the outer cover 4 are joined by a method such as thermocompression bonding using the joining tool 40, thereby forming the joint portion 5 (step SB5). As shown in FIG. 12A, the region to be joined is the region between two adjacent engaging portions 2b arranged in the same slack portions 6 and 7, and the joint portion 5 is formed in the slack portions 6 and 7. The region to be joined may be the same as the joint portion 5 of the first embodiment. Further, as shown in FIG. 12B, a joint portion 5 having a large area may be formed in the wide slack portions 6 and 7. Next, by removing the mandrel 20 from inside the inner cover 3, a covered stent having the slack portions 6 and 7 is manufactured (step SB6).

[0039] Thus, according to the manufacturing method of the present embodiment, both covers 3 and 4 have slack due to the slack portions 6 and 7, and a covered stent with a low axial force and high flexibility that does not prevent the bending of the stent body 2 can be manufactured. Further, by inserting the covers 3 and 4 into the concave portion 20a of the mandrel 20, slack portions 6 and 7 having the same dimensions as the concave portion 20a are formed. Thereby, the dimensions of the slack portions 6 and 7 can be easily and accurately controlled to form the slack portions 6 and 7 having desired dimensions. In the present embodiment, the slack portions 6 and 7 may have a shape that deforms into a predetermined folding shape as shown in FIGS. 8A and 9A, similar to the first embodiment.

[0040] In the present embodiment, the slack portion 6 and the slack portion 7 are formed in different steps SB41 and SB42, but instead, the slack portions 6 and 7 may be formed simultaneously in one step SB4. FIGS. 13 and 14 illustrate a first modification of the manufacturing method of the second embodiment. In this modification, the step SB4 of forming the slack portions 6 and 7 is performed by simultaneously pushing the inner cover 3 and the outer cover 4 into the concave portion 20a using the pushing tool 30 after the step SB3. According to this modification, the number of steps can be reduced.

[0041] The formation of the slack portions 6 and 7 and the joining of the covers 3 and 4 may be simultaneously performed in one step SB45. FIGS. 15 and 16 illustrate a second modification of the manufacturing method of the second embodiment. In this modification, step SB45 is performed by joining the covers 3 and 4 to each other by the joining tool 40 while simultaneously pushing the covers 3 and 4 into the recess 20a using a joining tool 40 such as a pin for pressing or heating, after step SB3. According to this modification, the number of steps can be further reduced.

[0042] In the present embodiment, the slack portion 6 is formed and then the covers 3 and 4 are joined. Instead of this, the covers 3 and 4 may be joined (step SB5), and then the slack portions 6 and 7 may be formed (step SB4). FIGS. 17 and 18 illustrate a third modification of the manufacturing method of the second embodiment. In this modification, like the joint portion 5 of the first embodiment (see FIG. 2A), the inner cover 3 and the outer cover 4 are joined to each other in the region inside the mesh on the convex portion 20b, and the joint portion 5 is formed (step SB5). Thereafter, the covers 3 and 4 are pushed into the recess 20a, and the slack portions 6 and 7 are formed by the stretching of the covers 3 and 4 (step SB4).

[0043] (Third Embodiment) Next, a manufacturing method and a cover stent according to a third embodiment of the present invention will be described. In the present embodiment, a configuration different from that of the first embodiment will be described, and the same reference numerals will be given to the configurations common to the first embodiment, and the description thereof will be omitted. The cover stent according to the present embodiment includes a stent body 2, an inner cover 3, and an outer cover 4. The cover stent of the present embodiment is different from the cover stent 1 of the first embodiment in that the stent body 2 is disposed in the slack portion 6 of the inner cover 3 (see FIG. 21).

[0044] The inner cover 3 has a plurality of slack portions 6 that extend in the circumferential direction and are arranged in the longitudinal direction, in addition to a plurality of slack portions 6 that extend in the longitudinal direction and are arranged in the circumferential direction. These slack portions 6 are continuous with each other, and a lattice-shaped recess is formed in the inner cover 3 as a whole. The wire 2a of the stent body 2 is disposed within the slack portion 6.

[0045] As shown in FIG. 19, the manufacturing method of the covered stent according to the present embodiment includes a step SC1 of disposing the inner cover 3 on the first jig 21, a step SC2 of disposing the stent body 2 outside the inner cover 3 to form the slack portion 6, a step SC3 of disposing the outer cover 4 outside the stent body 2, a step SC4 of joining the inner cover 3 and the outer cover 4 to each other, and a step SC5 of removing the covered stent from the jig 21.

[0046] As shown in FIG. 20, the jig 21 has a plurality of convex portions 21b that are arranged at intervals in the longitudinal direction and the circumferential direction. The convex portion 21b is a columnar protrusion that protrudes radially outward from the outer peripheral surface of the jig 21. Between the convex portions 21b, a recess 21a extending in the circumferential direction and a recess 21a extending in the longitudinal direction are formed, and these recesses 21a are continuous with each other. As shown in FIG. 21, the inner cover 3 is disposed on the convex portion 21b of the mandrel 20 (step SC1).

[0047] Next, the stent body 2 is disposed on the outer surface of the inner cover 3 so that the convex portion 21b is positioned inside the mesh. As a result, the inner cover 3 is recessed radially inward in the region of the recess 21a, and the slack portion 6 is formed in the recess 21a (step SC2). Next, the outer cover 4 is disposed outside the inner cover 3, and the stent body 2 is covered by the outer cover 4 (step SC3). Next, the joint portion 5 is formed by joining the inner cover 3 and the outer cover 4 in the region of the convex portion 21b (step SC4). Next, by removing the mandrel 21 from inside the inner cover 3, a covered stent having the slack portion 6 is manufactured (step SC5).

[0048] Thus, according to the manufacturing method of the present embodiment, since the slack portion 6 is formed by disposing the stent body 2 on the inner cover 3, a special pushing tool 30 is unnecessary. Further, since the entire inner cover 3 is evenly pressed radially inward by the stent body 2, the dimensions of the slack portion 6 can be easily and accurately controlled to form the slack portion 6 having a desired dimension without using the pushing tool 30. Also, since only the inner cover 3 has the slack portion 6 and the outer cover 4 does not have a slack portion, the sliding resistance when releasing the cover stent from the delivery system can be reduced. In the present embodiment, a plurality of recesses 21a in the circumferential direction and the longitudinal direction are continuous with each other. However, instead of this, they may be independent of each other like the recess 20a of the first embodiment.

[0049] (Fourth Embodiment) Next, a manufacturing method and a cover stent according to a fourth embodiment of the present invention will be described. In the present embodiment, a configuration different from that of the first embodiment will be described, and the same reference numerals will be given to the configurations common to the first embodiment and the description thereof will be omitted. The cover stent according to the present embodiment includes a stent body 2, an inner cover 3, and an outer cover 4. The cover stent of the present embodiment is different from the cover stent 1 of the first embodiment in that the inner cover 3 does not have a slack portion 6 and the outer cover 4 has a slack portion 7 that bulges radially outward.

[0050] The outer cover 4 has a plurality of slack portions 7 arranged at intervals in the longitudinal direction. Each slack portion 7 is a concave portion that extends over the entire circumference of the outer cover 4 and bulges radially outward. Some engaging portions 2b are disposed between the inner cover 3 and the slack portion 7. The slack portion 7 forms a space between the inner cover 3 and the outer cover 4 and imparts slack to the outer cover 4. Therefore, similar to the inner cover 3 of the first embodiment, the outer cover 4 allows the longitudinal and radial movement of the pair of bent portions 2c, 2d forming the engaging portion 2b, and it is prevented that the covers 3, 4 interfere with the three-dimensional displacement of the bent portions 2c, 2d when the cover stent 1 is bent. Thereby, low axial force and high flexibility of the cover stent are realized.

[0051] As shown in FIG. 22, the manufacturing method of the cover stent according to the present embodiment includes a step SD1 of disposing the inner cover 3 on the first jig 22, a step SD2 of disposing the inner cover 3 inside the stent body 2, a step SD3 of disposing the outer cover 4 on the second jig 23, a step SD4 of forming the slack portion 7 in the outer cover 4, a step SD5 of disposing the outer cover 4 outside the inner cover 3, a step SD6 of joining the inner cover 3 and the outer cover 4 to each other, and a step SD7 of removing the cover stent from the jigs 22, 23.

[0052] FIGS. 23A to 23C show the jigs 22, 23 used in the present embodiment. The first jig 22 is a columnar mandrel, and the outer surface of the mandrel 22 is a cylindrical surface without irregularities. The second jig 23 is a cylindrical member, and a plurality of concave portions 23b arranged at intervals in the longitudinal direction are formed on the cylindrical inner surface (mounting surface) 23a of the second jig 23. The plurality of concave portions 23b are structures for forming the slack portion 7. Each concave portion 23b extends over the entire circumference and is recessed radially outward. As shown in FIGS. 23B and 23C, the second jig 23 may be composed of two semi-cylindrical halves 231, 232 in order to expose the inner surface 23a. The two halves 231, 232 may be separated from each other (see FIG. 23B), or may be connected so as to be openable and closable (see FIG. 23C).

[0053] As shown in FIG. 24, in the same manner as in step SA1, the inner cover 3 is disposed on the outer surface of the mandrel 22 (step SD1). Next, in the same manner as in step SA3, the stent body 2 is disposed on the outer surface of the inner cover 3 (step SD2). Next, the outer cover 4 is disposed on the inner surface 23a of the second jig 23 (step SD3). Next, the outer cover 4 is pushed into the recess 23b by using a pushing tool 30 (not shown), thereby forming the slack portion 7 (step SD4).

[0054] Next, by inserting the mandrel 22 into the second jig 23, the outer cover 4 is disposed outside the stent body 2 (step SD5). Here, the outer cover 4 is aligned with the stent body 2 at a position where the joining mechanism (not shown) provided in the second jig 23 is disposed at the center of the mesh of the stent body 2. The joining mechanism is a mechanism for joining the covers 3 and 4. For example, the joining mechanism is a pin that protrudes from the inner surface 23a of the second jig 23 and presses or heats the covers 3 and 4, or a through hole into which a separate joining tool is inserted from the outside to the inside of the second jig 23.

[0055] Next, the covers 3 and 4 are joined in a partial region inside the mesh by using the joining mechanism, thereby forming the joint portion 5 (step SD6). Next, by removing the mandrel 22 from inside the inner cover 3, a cover stent having the slack portion 7 is manufactured (step SD7).

[0056] Thus, according to the manufacturing method of the present embodiment, the outer cover 4 has a slack due to the slack portion 7, and the covers 3 and 4 can manufacture a cover stent having a low axial force and high flexibility that do not prevent the bending of the stent body 2. Further, by inserting the outer cover 4 into the recess 23b of the second jig 23, a slack portion 7 having the same dimensions as the recess 23b is formed. Thereby, the dimensions of the slack portion 7 can be easily and accurately controlled to form the slack portion 7 having desired dimensions. Also, among the double covers 3 and 4, only the outer cover 4 has the slack portion 7, and the inner cover 3 does not have a slack portion. Therefore, the inner surface of the cover stent becomes a smooth surface without irregularities, and substances in the body can flow smoothly through the hollow portion inside the cover stent.

[0057] In this embodiment, it is assumed that the inner cover 3 does not have a slack portion. Instead of this, the inner cover 3 may have the slack portion 6 described in the first to third embodiments. In this case, instead of the first jig 22, a first jig having a concave portion such as the mandrels 20 and 21 of the first to third embodiments is used in combination with the second jig 23. Thereby, a cover stent can be manufactured in which the inner cover 3 has a slack portion 6 that bulges inward in the radial direction and the outer cover 4 has a slack portion 7 that bulges outward in the radial direction. Furthermore, the dimensions and shapes of the slack portion 6 and the slack portion 7 can be made different from each other.

[0058] (Fifth Embodiment) Next, a manufacturing method and a cover stent according to the fifth embodiment of the present invention will be described. This embodiment is a modification of the fourth embodiment and is different from the fourth embodiment in the manufacturing method of the cover stent. In this embodiment, configurations different from those of the first and fourth embodiments will be described, and configurations common to the first and fourth embodiments will be denoted by the same reference numerals and the description thereof will be omitted. The cover stent according to this embodiment includes a stent body 2, an inner cover 3, and an outer cover 4, and the outer cover 4 has a slack portion 7 that bulges outward in the radial direction.

[0059] The manufacturing method of the cover stent according to this embodiment includes steps SD1, SD2, SD3, SD4, SD5, SD6, and SD7 described in the fourth embodiment. FIG. 25A shows a second jig 24 used in this embodiment. The second jig 24 is a flat member having a rectangular flat mounting surface 24a, and a plurality of recesses 24b arranged at intervals in the longitudinal direction are formed in the mounting surface 24a. The recess 24b is a structure for forming the slack portion 7. Each recess 24b is composed of a groove extending over the entire width of the mounting surface 24a. The second jig 24 may be formed of a hard material, or may be formed of a flexible material such as silicone.

[0060] In this embodiment, the outer cover 4 is disposed on the mounting surface 24a of the second jig 24 (step SD3). Next, the slack portion 7 is formed by pushing the outer cover 4 into the recess 24b using the pusher 30 (step SD4). Next, as shown in FIG. 26A, the mounting surface 24a is rotated around the mandrel 22 and the outer cover 4 is wound around the mandrel 21, whereby the outer cover 4 is disposed on the stent body 2 (step SD5). After the outer cover 4 is disposed, the second jig 24 is removed. In FIGS. 26A and 26B, the illustrations of the stent body 2 and the inner cover 3 are omitted.

[0061] When the second jig 24 has flexibility, as shown in FIG. 26B, the outer cover 4 may be disposed on the stent body 2 by winding the second jig 24 around the mandrel 22. In this case, the inner cover 3 and the outer cover 4 may be joined using the joining mechanism and the like described in the fourth embodiment while the second jig 24 is wound around the mandrel 22 (step SD6), and then the second jig 24 may be removed.

[0062] Thus, according to the manufacturing method of this embodiment, the second jig 24 has a simple shape in which the recess 24b is processed in the flat mounting surface 24a. Therefore, recesses 24b having various shapes and dimensions can be formed with high precision, and a covered stent having slack portions 7 having various shapes and dimensions can be manufactured. FIG. 25B shows another example of the second jig 24. Thus, the recess 24b in the diagonal direction can also be easily formed. The second jig 24 in FIG. 26B is formed by winding and braiding the wire 2a in a spiral shape, and is used in combination with the stent body 2 in which the engaging portions 2b are arranged in a spiral shape.

[0063] In the present embodiment, similarly to the fourth embodiment, by using the first jig having a recess in combination with the second jig 24, a cover stent in which the inner cover 3 has a slack portion 6 and the outer cover 4 has a slack portion 7 may be manufactured. In the present embodiment, similarly to the first embodiment, the slack portions 6 and 7 may have a shape that deforms into a predetermined folding shape as shown in FIGS. 8A and 9A. FIGS. 27A and 27B show other examples of the shapes of the slack portions 6 and 7 that deform into a predetermined folding shape by radial compression. Thus, the shapes of the slack portions 6 and 7 can be variously changed.

[0064] In the above-described first, second, fourth, and fifth embodiments, the pusher 30 is used as a means for inserting the covers 3 and 4 into the recesses 20a, 23b, and 24b. However, other means may be used instead. For example, suction ports may be opened on the inner surfaces of the recesses 20a, 23b, and 24b, and the covers 3 and 4 may be sucked into the recesses 20a, 23b, and 24b by suction. Even by such means, the covers 3 and 4 can be inserted into the recesses 20a, 23b, and 24b and deformed along the inner surfaces of the recesses 20a, 23b, and 24b.

[0065] (Sixth Embodiment) Next, a method for manufacturing a cover stent and a cover stent according to the sixth embodiment of the present invention will be described. In the present embodiment, the configurations different from those in the first embodiment will be described, and the configurations common to the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted. As shown in FIG. 28A, the cover stent 10 according to the present embodiment includes a stent body 2, a tubular outer cover 41 that covers the outside of the stent body 2, and fixing covers 8 disposed inside both ends of the stent body 2.

[0066] The stent body 2 is deformable from an expanded state to a contracted state by radial contraction and is mounted on a delivery system in the contracted state. As shown in FIG. 28B, the stent body 2 extends in the longitudinal direction by radial contraction, and the length L2 of the stent body 2 in the contracted state increases by, for example, about 20% to 50% compared to the length L1 of the stent body 2 in the expanded state. The fixing cover 8 is formed of ePTFE and is disposed over the entire circumference inside both ends of the stent body 2. Both ends of the outer cover 41 are joined to the fixing cover 8, whereby the outer cover 41 is connected to the stent body 2 at both ends.

[0067] The outer cover 41 is formed of ePTFE and has a stretching direction A showing high ductility. That is, the outer cover 41 easily extends in the stretching direction A and hardly extends in a direction orthogonal to the stretching direction. Such stretching characteristics of the outer cover 41 are due to the manufacturing method of ePTFE. The manufacturing method of ePTFE includes a step of stretching PTFE and a step of sintering the stretched PTFE. By stretching PTFE, nodes distributed in an island shape and fibrils extending in the stretching direction between the nodes are formed, and ePTFE has high ductility in the stretching direction A in which the fibrils are oriented.

[0068] The outer cover 41 is arranged in a direction where the stretching direction A coincides with the longitudinal direction of the stent body 2. Also, in the expanded state, the outer cover 41 has slack in the longitudinal direction. That is, the total length of the outer cover 41 is the length obtained by adding an extra length to the length L1 of the stent body 2 in the expanded state. Such an outer cover 41 is deformable according to an external force in the expanded state and allows the longitudinal and radial movement of the pair of bent portions 2c, 2d forming the engaging portion 2b. Therefore, it is prevented that the outer cover 41 hinders the three-dimensional displacement of the bent portions 2c, 2d when the cover stent 10 is bent, and low axial force and high flexibility of the cover stent 10 are realized.

[0069] Furthermore, since the stretching direction A of the outer cover 41 coincides with the stretching direction of the stent body 2 when it contracts, it is prevented that the outer cover 41 is torn or peeled off from the stent body 2 due to the stretching of the stent body 2. When the ductility of the outer cover is low in the stretching direction of the stent body, damage such as the outer cover being torn or peeled off from the stent body may occur due to the contraction of the cover stent.

[0070] Next, a method for manufacturing the cover stent according to the present embodiment will be described. As shown in FIG. 29, the method for manufacturing the cover stent includes a step SE1 of preparing the outer cover 41 and the fixing cover 8, a step SE2 of arranging the fixing cover 8 on the jig 22, a step SE3 of arranging the fixing cover 8 inside the stent body 2, a step SE4 of arranging the outer cover 41 outside the stent body 2, a step SE5 of partially connecting the outer cover 41 to the stent body 2, and a step SE6 of radially contracting the stent body 2 and stretching the outer cover 41.

[0071] As shown in FIG. 30, considering the stretching direction A of ePTFE, a rectangular outer cover 41 and a strip-shaped fixing cover 8 are cut out from the ePTFE sheet (step SE1). The outer cover 41 has a length direction and a width direction corresponding to the longitudinal direction and the circumferential direction of the stent body 2, respectively. The outer cover 41 is cut out from the sheet so that the length direction of the outer cover 41 coincides with the stretching direction A of ePTFE.

[0072] Next, as shown in FIG. 31, the fixing cover 8 is wound around two locations of the jig 22 (step SE2). The jig 22 is a mandrel having a cylindrical outer surface without unevenness. Next, by inserting the mandrel 22 into the stent body 2, the fixing cover 8 is disposed inside both ends of the stent body 2 (step SE3). Next, by aligning the length direction of the outer cover 41 with the longitudinal direction of the stent body 2 and winding the outer cover 41 around the mandrel 22 over the entire circumference, the outer cover 41 is disposed outside the stent body 2 (step SE4).

[0073] Next, by joining both ends of the outer cover 41 to the fixing cover 8 by any joining method such as thermocompression bonding or an adhesive, the outer cover 41 is connected to the stent body 2 (step SE5). In step SE5, by joining the end portions in the width direction of the outer cover 41 to the other portions of the outer cover 41 over the entire length, the outer cover 41 is formed into a tubular shape. After joining, by removing the mandrel 22 from inside the stent body 2, the assembly of the stent body 2, the outer cover 41, and the fixing cover 8 is removed from the mandrel 22.

[0074] Next, by radially contracting the stent body 2, the outer cover 41 is stretched in the longitudinal direction together with the stent body 2 (step SE6). Step SE6 may be performed by inserting the assembly into a tube 50 having an inner diameter smaller than the diameter of the assembly in the expanded state. Thereby, the length of the outer cover 41 increases, and a slack is formed in the outer cover 41 with respect to the length of the stent body 2 in the expanded state.

[0075] Thus, according to the manufacturing method of the present embodiment, by simply radially contracting the stent body 2 to which the outer cover 41 is partially connected, a slack for allowing three-dimensional displacement of the bending portions 2c and 2d during bending is formed in the outer cover 41. Thereby, the covered stent 10 with low axial force and high flexibility can be easily manufactured. Furthermore, since the stretching direction A of the outer cover 41 coincides with the stretching direction of the stent body 2 during contraction, the covered stent 10 that is difficult to break and has high reliability can be easily manufactured.

[0076] In the present embodiment, the outer cover 41 is connected to the stent body 2 at both ends. However, the number and position of the connection portions of the outer cover 41 to the stent body 2 can be appropriately changed. For example, in order to increase the fixing force of the outer cover 41 to the stent body 2, the outer cover 41 may be connected to the stent body 2 at the central portion in addition to both ends. In the connection portion joined by thermocompression bonding or the like, the ductility of ePTFE is impaired because the structure of the nodes and fibrils is broken. Therefore, it is preferable that the number of connection portions is small.

[0077] In the present embodiment, the outer cover 41 is stretched by inserting the assembly into the tube 50. Instead of this, the outer cover 41 may be stretched by mounting the assembly on a delivery system. The delivery system has a tubular sheath inserted into the body cavity, and the covered stent 10 is mounted at the tip of the sheath. After step SE5, by inserting the assembly into the sheath, the stent body 2 can be contracted and the outer cover 41 can be stretched simultaneously with the mounting on the delivery system.

[0078] In the present embodiment, the manufacturing method includes the step SE6 of stretching the outer cover 41, but the step SE6 may not be included. In this case, the covered stent 10 is provided with the outer cover 41 in an unstretched state. The non-extended outer cover 41 is extended, for example, when the user mounts the cover stent 10 on the delivery system by himself / herself. Thereby, a slack is formed in the outer cover 41, and a low axial force of the cover stent 10 can be realized.

[0079] (Seventh Embodiment) Next, a manufacturing method of the cover stent and the cover stent according to the seventh embodiment of the present invention will be described. In the present embodiment, configurations different from those of the first and sixth embodiments will be described, and configurations common to the first and sixth embodiments will be denoted by the same reference numerals and the description thereof will be omitted. As shown in FIG. 32, the cover stent 11 according to the present embodiment is different from the cover stent 10 of the sixth embodiment in that, in addition to the stent body 2 and the outer cover 41, it further includes a tubular inner cover 31 that covers the inside of the stent body 2.

[0080] The covers 31 and 41 are partially joined to each other, and thereby are partially connected to the stent body 2. For example, the covers 31 and 41 are joined to each other at a joint portion 5 that is a partial region inside the mesh of the stent body 2, and are separated from each other at portions other than the joint portion 5. The inner cover 31 is formed of ePTFE, like the outer cover 41, has a stretching direction A showing high ductility, and the stretching direction A is arranged in a direction that coincides with the longitudinal direction of the stent body 2. Further, in the expanded state, the inner cover 31 has a slack in the longitudinal direction. That is, the total length of the inner cover 31 is a length obtained by adding an extra length to the length L1 of the stent body 2 in the expanded state.

[0081] Such an inner cover 31, like the outer cover 41, allows the longitudinal and radial movement of a pair of bent portions 2c and 2d that form the engaging portion 2b. Therefore, it is prevented that the covers 31 and 41 interfere with the three-dimensional displacement of the bent portions 2c and 2d when the cover stent 11 is bent, and a low axial force and high flexibility of the cover stent 11 are realized. Furthermore, since the stretching direction A of the covers 31 and 41 coincides with the stretching direction of the cover stent 11 when it contracts, it is possible to prevent the covers 31 and 41 from being damaged or peeled off from the stent body 2 due to the stretching of the stent body 2.

[0082] Next, a method for manufacturing the cover stent according to the present embodiment will be described. As shown in FIG. 33, the method for manufacturing the cover stent includes a step SF1 of preparing an inner cover 31 and an outer cover 41, a step SF2 of disposing the inner cover 31 on a jig 22, a step SF3 of disposing the inner cover 3 on the inside of the stent body 2, a step SF4 of disposing the outer cover 41 on the outside of the stent body 2, a step SF5 of partially connecting the inner cover 31 and the outer cover 41 to the stent body 2, and a step SF6 of radially contracting the stent body 2 and stretching the inner cover 31 and the outer cover 41.

[0083] Similar to step SE1, considering the stretching direction A of ePTFE, a rectangular outer cover 41 and a rectangular inner cover 31 are cut out from the ePTFE sheet so that the length direction of the covers 31 and 41 coincides with the stretching direction A (step SF1). Next, as shown in FIG. 34, by aligning the length direction of the inner cover 31 with the longitudinal direction of the mandrel 22 and winding the inner cover 31 around the mandrel 22 over the entire circumference, the inner cover 31 is disposed on the outer surface of the mandrel 22 (step SF2). In step SF2, the end portions in the width direction of the inner cover 31 are joined to the other portions of the inner cover 31 over the entire length, and the inner cover 31 is formed into a tubular shape.

[0084] Next, by inserting the mandrel 22 into the stent body 2, the stent body 2 is disposed outside the inner cover 31 (step SF3). Next, the outer cover 41 is disposed outside the stent body 2 by aligning the longitudinal direction of the outer cover 41 with the longitudinal direction of the stent body 2 and winding the outer cover 41 around the mandrel 22 over the entire circumference (step SF4). In step SF4, the end portions in the width direction of the outer cover 41 are joined to the other portions of the outer cover 41 over the entire length, and the outer cover 41 is formed into a tubular shape.

[0085] Next, the covers 31 and 41 are connected to the stent body 2 by joining the outer cover 41 and the inner cover 31 to each other by any joining method such as thermocompression bonding or an adhesive in a partial region inside the knitting to form a joint portion 5 (step SF5). After joining, the mandrel 22 is removed from the inner cover 31, and the assembly of the stent body 2 and the covers 31 and 41 is removed from the mandrel 22.

[0086] Next, in the same manner as in step SE6, the covers 31 and 41 are stretched in the longitudinal direction together with the stent body 2 by radially contracting the stent body 2 (step SF6). As a result, the length of each of the covers 31 and 41 increases, and slack is formed in each of the covers 31 and 41 with respect to the length of the stent body 2 in the expanded state.

[0087] Thus, according to the manufacturing method of the present embodiment, by simply radially contracting the stent body 2 to which the double covers 31 and 41 are partially connected, slack for allowing three-dimensional displacement of the bent portions 2c and 2d during bending is simultaneously formed in the covers 31 and 41. Thereby, the covered stent 11 with low axial force and high flexibility can be easily manufactured. Further, since the stretching direction A of the covers 31 and 41 coincides with the stretching direction of the stent body 2 during contraction, the covered stent 11 with high reliability in which the covers 31 and 41 are hardly damaged can be easily manufactured.

[0088] In step SF6 of the present embodiment, in the same manner as in the sixth embodiment, the covers 31 and 41 may be stretched by mounting the assembly on a delivery system instead of the tube 50. In the present embodiment, similar to the sixth embodiment, the manufacturing method may not include step SF6, and the cover stents 11 may be provided with the covers 31 and 41 in an unstretched state.

[0089] In the sixth and seventh embodiments, the stretching direction A of the covers 31 and 41 is made to coincide with the longitudinal direction of the stent body 2. However, in the case of the stent body 2 in which the wire 2a is wound in a spiral shape, the stretching direction A may coincide with the direction in which the wire 2a extends when the stent body 2 contracts. As shown in FIG. 35, the stent body 2 formed by braiding while winding the wire 2a in a spiral shape extends while rotating in the direction in which the twist is released when the diameter is reduced in the radial direction. Therefore, by making the stretching direction A coincide with the stretching direction of the wire 2a, the covers 31 and 41 can be effectively stretched. In this case, in steps SE1 and SF1, the covers 31 and 41 are cut out from an ePTFE sheet such that the length direction of the covers 31 and 41 is inclined with respect to the stretching direction A by an angle corresponding to the angle of the stretching direction of the wire 2a.

[0090] In the sixth and seventh embodiments, the stent body 2 is not limited to having the engaging portion 2b, and may be a stent body having another structure that extends in the longitudinal direction by contraction in the radial direction. Also, although the case where the covers 31 and 41 are arranged over the entire length of the stent body 2 is disclosed, the same effect can be obtained even when the covers are arranged on a part of the stent body 2.

[0091] Furthermore, also in the first to fifth embodiments, in the arrangement of the ePTFE-made cover and the stent body, the stretching direction of the covers 31 and 41 and the stretching direction of the stent body 2 can be made to coincide with each other.

[0092] As described above, the embodiments and modifications of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to the above-described embodiments, and also includes design changes and the like within the scope not departing from the gist of the present invention. Also, the components shown in the above-described embodiments and modifications can be configured by appropriately combining them.

Explanation of Symbols

[0093] 1, 10, 11 Cover stent 2 Stent body 2a Wire 2b Engaging part 2c, 2d Bending part 3, 31 Inner cover 4, 41 Outer cover 5 Joint part 6, 7 Slack part 20, 21, 22 First jig (mandrel) 23, 24 Second jig 23a, 24a Placing surface 20a, 21a, 23b, 24b Concave part

Claims

1. A method for manufacturing a covered stent, comprising: placing an inner cover inside a stent body having a mesh structure formed by weaving wires, wherein the stent body has an engaging portion where two bent portions of the wires are hooked to each other; placing an outer cover outside the stent body; forming a slack portion that bulges in the radial direction of the stent body in at least one of the inner cover and the outer cover, and imparting to the at least one of the inner cover and the outer cover a slack that allows movement of the two bent portions in the longitudinal direction and the radial direction of the stent body; and joining the inner cover and the outer cover to each other in a region inside the meshes of the mesh structure. A method for manufacturing a covered stent, comprising the above steps.

2. further comprising placing the inner cover on an outer surface of a columnar first jig, wherein forming the slack portion includes forming the slack portion in the inner cover by inserting the inner cover into a recess formed on the outer surface of the first jig before placing the outer cover. The method for manufacturing a covered stent according to claim 1.

3. wherein forming the slack portion includes forming the slack portion in the outer cover by inserting the outer cover into the recess of the first jig after placing the outer cover. The method for manufacturing a covered stent according to claim 2.

4. further comprising placing the inner cover on an outer surface of a columnar first jig, wherein forming the slack portion includes forming the slack portion in the inner cover and the outer cover by simultaneously inserting the inner cover and the outer cover into a recess formed on the outer surface of the first jig after placing the outer cover. The method for manufacturing a covered stent according to claim 1.

5. wherein forming the slack portion and the joining are performed simultaneously by joining the inner cover and the outer cover to each other with a joining tool while pushing the inner cover and the outer cover into the recess with the joining tool. The method for manufacturing a covered stent according to claim 4.

6. further comprising placing the inner cover on an outer surface of a columnar first jig, Placing the stent body is to align a protrusion provided on the outer surface of the first jig with an area inside the mesh of the mesh structure and place the stent body on the outer surface of the inner cover, thereby forming the slack portion in the inner cover. The manufacturing method of the covered stent according to claim 1.

7. Further including placing the outer cover on the placement surface of the second jig, Forming the slack portion includes forming the slack portion in the outer cover by inserting the outer cover into a recess formed in the placement surface of the second jig before placing the outer cover outside the stent body. The manufacturing method of the covered stent according to claim 1.

8. The second jig has either a cylindrical member whose inner surface is the placement surface or a flat member having the flat placement surface. The manufacturing method of the covered stent according to claim 7.

9. The slack portion extends in the circumferential direction of the stent body. The manufacturing method of the covered stent according to claim 1.

10. The inner cover and the outer cover are joined to each other in a region between two adjacent engaging portions disposed in the slack portion. The manufacturing method of the covered stent according to claim 9.

11. A plurality of the slack portions are formed at intervals in the longitudinal direction of the stent body, The inner cover and the outer cover are joined to each other in a region between two adjacent slack portions. The manufacturing method of the covered stent according to claim 9.

12. The slack portion has a shape that deforms into a predetermined folded shape by the radial compression force, In the predetermined folded shape, a part of the cover constituting the slack portion overlaps in the radial direction outside the opening of the slack portion. The manufacturing method of the covered stent according to claim 1.

13. The inner cover is made of ePTFE, and the inner cover is arranged with respect to the stent body in a direction in which the stretching direction of ePTFE coincides with the stretching direction of the stent body when the stent body contracts in the radial direction. The manufacturing method of the covered stent according to claim 1.

14. The manufacturing method of the covered stent according to claim 1, wherein the outer cover is made of ePTFE, and the outer cover is arranged with respect to the stent body such that the stretching direction of ePTFE coincides with the stretching direction of the stent body when the stent body contracts in the radial direction.

15. A stent body having a mesh structure formed by braiding wires, the stent body having an engaging portion where two bent portions of the wires are hooked on each other, an inner cover covering the inside of the stent body, and an outer cover covering the outside of the stent body, wherein at least one of the inner cover and the outer cover has a slack portion that bulges in the radial direction of the stent body, and the slack portion imparts a slack to at least one of the inner cover and the outer cover that allows movement of the two bent portions in the longitudinal direction and the radial direction of the stent body, A covered stent, wherein the inner cover and the outer cover are joined to each other in a region inside the mesh of the mesh structure.

16. The covered stent according to claim 15, wherein the inner cover is made of ePTFE, and the inner cover is arranged with respect to the stent body such that the stretching direction of ePTFE coincides with the stretching direction of the stent body when the stent body contracts in the radial direction.

17. The covered stent according to claim 15, wherein the outer cover is made of ePTFE, and the outer cover is arranged with respect to the stent body such that the stretching direction of ePTFE coincides with the stretching direction of the stent body when the stent body contracts in the radial direction.

18. An ePTFE - made cover is arranged on at least one of the inside and the outside of the stent body in a direction such that the stretching direction of ePTFE coincides with the stretching direction of the stent body when the stent body contracts in the radial direction, the cover is partially connected to the stent body, and a slack is generated in the cover by contracting the stent body in the radial direction and stretching the cover. A manufacturing method of a covered stent.

19. The manufacturing method of the covered stent according to claim 18, wherein contracting the stent body in the radial direction and stretching the cover are performed in a step of mounting the stent body to which the cover is connected on a delivery system.

20. A stent body, A cover made of ePTFE that covers at least one of the inner and outer sides of the stent body and is partially connected to the stent body. The cover is arranged in a direction in which the stretching direction of ePTFE coincides with the stretching direction of the stent body in the radial contraction of the stent body, and The cover is a covered stent having a slack in the longitudinal direction of the stent body in a state where the stent body is expanded in the radial direction.

Images