Stent

Abstract

To provide a covered stent preventing a stent body and a membrane from shifting, preventing the membrane from tearing or expanding in an outer diameter, and securing flexibility of deformation.SOLUTION: A peripheral surface of a stent body 10 made of a metal wire 11 woven into a tubular and reticulated shape is covered with a membrane 20 in an axial direction and a circumferential direction. A restraining membrane 30 provided on an axial end of the stent body 11, the body end portion 15, is welded to an axial end of the membrane 20, the membrane end portion 25, so as to restrain the body end portion 15 and the membrane end portion 25 together. An axially inner portion 16 with respect to the main body end portion 15, of the stent main body 10 and an axially inner portion 26 with respect to the membrane end portion 25, of the membrane 20 are free from the restraint.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a stent for expanding a narrowed portion of a body lumen, and more particularly to a covered stent in which a stent body made of a metal mesh is covered with a membrane (cover). [Background technology]

[0002] For example, when a body lumen such as the large intestine is narrowed by a lesion such as colon cancer, a stent is known as a surgical tool for expanding the narrowed portion. A covered stent is a type of stent. A covered stent is a tubular stent body made of a metal mesh woven from metal wires covered with a membrane (cover) made of a resin film. The mesh of the stent body is blocked by the membrane, which prevents the tissue of the expanded lesion from penetrating the stent body through the mesh and causing restenosis.

[0003] In a covered stent, the stent body and the membrane body are fixed with threads at both ends in the axial direction, at several points in the center, and at several points in the circumferential direction. The threads are passed through the membrane body and tied to the stent body. An adhesive is applied to the knots. A covered stent in which the stent body and the membrane body are not fixed to each other is also known.

[0004] In Patent Document 1, the stent body is covered from the inside and outside with an inner membrane and an outer membrane, and these membranes are heated and fully welded together, thereby fixing the entire stent body to the inner membrane and the outer membrane. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2005-000518 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the case of a covered stent that uses thread as a means for fixing the stent body and the membrane, it is necessary to make a hole in the membrane with a needle to pass the thread through, and there is a risk that the membrane will tear from the hole. In addition, a bulge is formed on the outer periphery of the covered stent due to the knot of the thread, which increases the outer diameter of the covered stent. In the case of a covered stent in which the stent body and the membrane body are not fixed to each other, there is a risk that the stent body and the membrane body may become displaced during the procedure for placing the stent in the narrowed area or during placement after the procedure.

[0007] In the case of a covered stent in which the entire stent body is fixed to a membrane by welding or the like, as in Patent Document 1, there is a risk that flexibility will be lost, and it is thought that it will be difficult to freely bend the covered stent according to the bending condition of the lesion, etc. In view of the above circumstances, the present invention aims to prevent the stent body and membrane from shifting in a covered stent, prevent the membrane from tearing or expanding in outer diameter, and ensure freedom of deformation. [Means for solving the problem]

[0008] In order to solve the above problems, the stent according to the present invention comprises: A stent body made of a tubular and mesh-like braided metal wire; A membrane body that circumferentially covers at least a portion of the peripheral surface of the stent body; a constraining membrane provided at the axial end of the stent body or at a body end portion in the vicinity thereof, and welded to the axial end of the membrane body or at a membrane end portion in the vicinity thereof, thereby constraining the body end portion and the membrane end portion together; A first characteristic form of the covered stent is a covered stent having an axially inner portion of the stent body from the body end portion and an axially inner portion of the membrane body from the membrane end portion, both of which are free from the restraint.

[0009] According to this stent, by restraining the stent body and the membrane, it is possible to prevent the stent body and the membrane from slipping apart. Since the restraining means is formed by welding the membrane and the restraining membrane, it is possible to prevent the membrane from tearing or its outer diameter from expanding. In addition, since the stent body and the membrane are restrained only at the axial end of the stent, it is possible to prevent the stent's freedom of deformation from being impaired.

[0010] In the first characteristic embodiment of the present invention, the constraining film has a ring shape whose width dimension along the axial direction is smaller than its circumference. This ensures that the axially inner portions of the stent body and the membrane body are not constrained from each other, ensuring the freedom of deformation of the stent.

[0011] In a further preferred embodiment of the present invention, in the first characteristic embodiment or preferred embodiment, the metal wire is sandwiched between the welded portions of the membrane end portion and the restraining membrane. This allows the metal wire, and therefore the stent body and the membrane end portion to be securely restrained and joined.

[0012] A further preferred embodiment of the present invention is that, in the first characteristic form or any of the preferred forms, the welded portion is arranged on a hypotenuse portion connecting two adjacent intersections in a diagonal direction to the axial direction in one wire portion, avoiding an intersection portion formed by the intersection of two wire portions of the metal wire. This allows the oblique side portion and therefore the stent body and the membrane end portion to be securely restrained and joined, and by welding avoiding the intersection portions, the degree of freedom of deformation of the stent can be ensured.

[0013] A further preferred embodiment of the present invention is that, in the first characteristic form or any of the preferred forms, the welded portions of the membrane end portion and the restraining membrane are disposed in a dispersed manner at multiple locations in the circumferential direction. This makes it possible to prevent the stent body and the membrane from slipping from each other, while ensuring the freedom of deformation of the stent.

[0014] The present invention relates to a stent body that is made of a tubular, mesh-like braided metal wire and extends in an axial direction; a membrane body that circumferentially covers at least a portion of either the inner surface or the outer surface of the stent body; a constraining membrane disposed on a surface of the stent body opposite to the one surface thereof so as to sandwich the stent body between the membrane body and the constraining membrane, the constraining membrane being welded to at least a portion of the membrane body; The second characteristic form of the stent is a stent having the above-mentioned welded portion between the membrane body and the restraining membrane, which is arranged so as to sandwich at least one wire portion of the metal wire, and which is provided so as to avoid an intersection portion where two wire portions of the metal wire cross each other.

[0015] Preferably, in the second characteristic form, the constraining membrane is provided at least near both ends of the membrane body in the axial direction. Preferably, in the second characteristic form, the constraining membrane includes a first constraining membrane provided near the axial proximal end of the membrane body and a second constraining membrane provided near the axial distal end of the membrane body, and the first constraining membrane and the second constraining membrane are arranged spaced apart in the axial direction.

[0016] The stent in the first or second characteristic aspect or any of the preferred aspects may include a second stent body arranged to sandwich the membrane body between the stent body and a second stent body.

[0017] The present invention relates to a stent body that is made of a tubular, mesh-like braided metal wire and extends in an axial direction; a membrane body circumferentially covering at least a portion of an outer surface of the stent body; a restraining membrane disposed on the inner surface of the stent body so as to sandwich the stent body between the membrane body and the restraining membrane, the restraining membrane being welded to only end regions of the membrane body in the axial direction; A stent comprising the above is defined as a third characteristic form.

[0018] The present invention relates to a stent body that is made of a tubular, mesh-like braided metal wire and extends in an axial direction; a membrane body circumferentially covering at least a portion of the inner surface of the stent body; a restraining membrane disposed on the outer surface of the stent body so as to sandwich the stent body between the membrane body and the restraining membrane, the restraining membrane being welded to only end regions of the membrane body in the axial direction; a second stent body disposed so as to sandwich the membrane body between the second stent body and the stent body; A stent comprising the above is a fourth characteristic form. Effect of the Invention

[0019] According to the stent of the present invention, it is possible to prevent the stent body and the membrane from being displaced from each other, and also to prevent the membrane from being torn or its outer diameter from expanding. Furthermore, it is possible to ensure the degree of freedom of deformation of the stent. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a side view of a covered stent according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged side view of the circle II in FIG. [Diagram 3] FIG. 3 is an enlarged cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a side view of a covered stent according to the first modified embodiment of the present invention. [Diagram 5] FIG. 5 is a side view of a covered stent according to the second modified embodiment of the present invention. [Figure 6] FIG. 6 is a side view of a covered stent according to a third modified embodiment of the present invention. [Figure 7] FIG. 7 is an enlarged cross-sectional view of a covered stent according to the fourth modified embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First Embodiment As shown in Fig. 1, the covered stent 1 includes a stent body 10, a membrane body 20, and a restraining membrane 30. The stent body 10 is composed of metal wires 11 and is formed into a tubular shape with a mesh structure. The metal wires 11 are woven into a mesh-like, tubular shape.

[0022] As shown in Fig. 2, two wire portions 12 of the metal wire 11 are crossed to form an intersection 13 (hook). A portion connecting two adjacent intersections 13A, 13B in a diagonal direction to the axial direction (left-right direction in Fig. 2) in one wire portion 12A constitutes a hypotenuse 14. A diamond-shaped mesh 19 (cell) is constituted by four hypotenuses 14 forming a diamond shape.

[0023] As shown in Fig. 1, a membrane body 20 is provided on the outer periphery of a stent body 10. The membrane body 20 is made of a resin film containing, for example, polytetrafluoroethylene (PTFE) as a main component, and is formed into a tubular shape. The membrane body 20 may be formed into a tubular shape by spirally winding a long strip-shaped resin film. Almost the entire outer periphery (circumferential surface) of the stent body 10 is covered by the membrane body 20 in the axial and circumferential directions. Both axial ends of the stent body 10 protrude outward from the membrane body 20.

[0024] As shown in Figs. 1 and 2, a constraining membrane 30 is provided on the inner circumference of the main body end portion 15 near both ends in the axial direction of the stent main body 10. The constraining membrane 30 includes a first constraining membrane 33 provided near the proximal end 20e (hand-side end) in the axial direction of the membrane body 20, and a second constraining membrane 34 provided near the distal end 20f in the axial direction of the membrane body 20. The constraining membranes 30 (33, 34) are made of a resin film containing, for example, polytetrafluoroethylene (PTFE) as a main component. The constraining membrane 30 is annular in which the width dimension along the axial direction of the stent 1 is smaller than the circumference. The constraining membrane 30 may be formed by winding a strip-shaped resin film into an annular shape.

[0025] As shown in Fig. 3, a membrane end portion 25 near the axial end of the membrane body 20 and the constraining membrane 30 are overlapped so as to sandwich the main body end portion 15 between them. As shown in Fig. 1, the constraining membrane 30 is disposed only at the end of the stent 1, and is not disposed in the axially inner portion of the end of the stent 1.

[0026] As shown in Figures 2 and 3, the constraining membrane 30 is partially heat-welded to the membrane end portion 25, thereby constraining the main body end portion 15 and the membrane end portion 25 from each other. That is, as shown by the diagonal hatching in Figure 2, a portion 31 of the constraining membrane 30 and a portion 25a of the membrane end portion 25 are heat-welded to each other. In Figure 2, the portions other than the diagonal hatching are non-welded portions. As shown in Figure 3, at least one wire portion 12A of the metal wire 11 is sandwiched between these welded portions 31, 25a (hereinafter referred to as "welded portion A"), thereby constraining the main body end portion 15 and the membrane end portion 25.

[0027] As shown in Fig. 1, the welded portions A are distributed and disposed at a plurality of locations in the circumferential direction of the main body end portion 15. Preferably, the welded portions A are disposed in a row at regular intervals in the circumferential direction of the main body end portion 15. More preferably, as shown in Figs. 1 and 2, the welded portions A are disposed to avoid the intersections 13 in the main body end portion 15, and are disposed at each of the two oblique side portions 14A in one direction (e.g., downward to the right in Fig. 2) of the two oblique side portions 14 in the main body end portion 15. Therefore, every other oblique side portion 14 in the circumferential direction of the main body end portion 15 is passed through the welded portion A, and is thereby constrained to the membrane end portion 25. In addition, the welded portion A may be arranged at every several oblique side portions 14 in the circumferential direction of the main body end portion 15, may be arranged at every every oblique side portion 14 in the circumferential direction of the main body end portion 15, or may be arranged randomly in the circumferential direction of the main body end portion 15.

[0028] As shown in FIG. 1, the axially inner portion 16 of the stent body 10 relative to the body end portion 15 and the axially inner portion 26 of the membrane body 20 relative to the membrane end portion 25 are free from the constraint by the constraint membrane 30 and can be displaced relative to each other.

[0029] According to the stent 1, by restraining the main body end portion 15 of the stent main body 10 and the membrane end portion 25 of the membrane 20 by the restraining membrane 30, it is possible to prevent the membrane 20 of the stent main body 10 from shifting in the axial direction. Because the restraining means is formed by welding the membrane body 20 and the restraining membrane 30, there is no risk of the membrane body 20 tearing, expanding, or having a step. This makes it possible to prevent the outer diameter of the stent 1 from increasing. By reducing the diameter of the stent 1, the stent 1 can be easily incorporated into a delivery system for delivering the stent to the narrowed portion of the body lumen, improving the ease of assembly of the delivery system.

[0030] In addition, the stent body 10 and the membrane body 20 are constrained only at the axial end of the stent 1, and the inner portion 16 of the stent body 10 and the inner portion 26 of the membrane body 20 can be displaced relative to each other without being constrained, so that the degree of freedom of deformation of the stent 1 can be avoided from being impaired. Furthermore, by arranging the welded portion A to avoid the intersection portion 13 of the metal wire 11, the degree of freedom of deformation of the stent 1 can be reliably ensured. Furthermore, by welding every other oblique side portion 14 in the circumferential direction of the main body end portion 15, the constrained portion can be minimized, and the degree of freedom of the stent 1 can be further increased. Therefore, the stent 1 can be made to flexibly follow the curvature of the body lumen during treatment.

[0031] Next, another embodiment of the present invention will be described. In the following embodiment, the same reference numerals are given to the same components as those in the above-described embodiment, and the description thereof will be omitted. <Modification 1> 4, an annular constraining membrane 30 is welded to the membrane body 20 over the entire circumference. The welded portion A is annular and extends over the entire length of the stent 1 in the circumferential direction.

[0032] <Modification 2> As long as the restraining membrane restrains the membrane body 20 and the stent body 11 by welding to the membrane body 20, it is not necessary to sandwich the metal wire 11 between the membrane body 20 and the stent body 11. For example, as shown in Fig. 5, each welded portion A may be disposed on the inner side of the mesh 19 so as not to come into contact with the metal wire 11.

[0033] <Modification 3> The constraining membrane does not necessarily have to be annular, and may be in the form of small pieces, so long as it is capable of constraining the membrane body 20 and the stent body 11 by welding to the membrane body 20. As shown in Fig. 6, a small piece of the constraining membrane 32 may be welded to the membrane body 20 with the metal wire 11 sandwiched therebetween. A plurality of small piece-shaped constraining membranes 32 consisting only of welded portions 31 may be arranged at intervals in the circumferential direction of the stent.

[0034] <Modification 4> In the modified embodiment shown in FIG. 7, the stent 1D has a double stent structure consisting of a stent body 11 (first stent body) and a second stent body 17 arranged on its inner circumference (lower right side in FIG. 7). A membrane body 30 is sandwiched between these two stent bodies 11, 17. Therefore, the membrane body 30 covers the inner circumference of the stent body 11 (lower right side in FIG. 7). The restraining membrane 30 covers the outer circumference of the first stent body 11 (upper and lower left sides in FIG. 7) and is welded to the membrane body 30, thereby restraining the first stent body 11 and the membrane body 20. Although detailed illustration is omitted, the first stent body 11 and the second stent body are restrained to each other at both axial ends by directly entangling the metal wires with each other.

[0035] The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, the means for welding the membrane 20 and the constraining membrane 30 is not limited to thermal welding, but may be high-frequency welding, ultrasonic welding, or the like. The membrane body 20 need only circumferentially cover at least a portion of either the inner or outer surface of the stent body, and does not need to cover substantially the entire inner surface or substantially the entire outer surface of the stent body. It may be positioned only at the axial end of the stent body 10 or a body end portion 15 nearby it, or it may be positioned only in the axial middle portion of the stent body 10. The constraining membranes 30 (33, 34) may be disposed on the surface opposite to the one surface of the stent body so as to sandwich the stent body between the membrane body 20 and the constraining membranes 30 (33, 34), and may be welded to at least a portion of the membrane body 20. The constraining membranes 30 (33, 34) do not necessarily need to be disposed at the axial end of the membrane body 20 or at the membrane body end portion 25 in the vicinity thereof, but may be disposed in a portion inside the membrane body end portion 25 in the axial direction of the membrane body 20 or in a middle portion of the membrane body 20 in the axial direction. [Industrial Applicability]

[0036] The present invention is applicable to a stent for dilating a narrowed portion of a body lumen. [Explanation of symbols]

[0037] 1,1D Covered stent (stent) 10 Stent body 11 Metal wire 12 Two wire parts 12A 1 wire part 13 Intersection 13A Intersection 13B Intersection 14 Hypotenuse 14A Hypotenuse 15 Body end part 16 Inner part 17 Second stent body (second stent body) 19 Mesh 20 Membrane body 20e Proximal end 20f Distal end 25 Membrane end portion 25a Welded part 26 Inner part 30 Annular Constraint Membrane (Constraint Membrane) 31 Welded parts 32 Piece-shaped restraining film (restricting film) 33 First Confinement Membrane 34 Second Constraint Membrane A Welded part

Claims

1. A stent body made of a tubular and mesh-like braided metal wire; A membrane body that circumferentially covers at least a portion of the peripheral surface of the stent body; a constraining membrane provided at the axial end of the stent body or at a body end portion in the vicinity thereof, and welded to the axial end of the membrane body or at a membrane end portion in the vicinity thereof, thereby constraining the body end portion and the membrane end portion together; a portion of the stent body that is axially inner than the body end portion and a portion of the membrane body that is axially inner than the membrane end portion are both free from the restraint.

2. 2. The stent according to claim 1, wherein the constraining membrane is annular in shape, the width dimension along the axial direction being smaller than the circumference.

3. 2. The stent according to claim 1, wherein the metal wire is sandwiched between the welded portions of the membrane end portion and the restraining membrane.

4. 2. The stent according to claim 1, wherein the welded portion between the membrane end portion and the restraining membrane is arranged on a hypotenuse portion connecting two adjacent intersections in a diagonal direction to the axial direction in one wire portion, avoiding an intersection where two wire portions of the metal wire intersect.

5. 2. The stent according to claim 1, wherein the welded portions between the membrane end portions and the restraining membrane are disposed in a plurality of dispersed locations in the circumferential direction.

6. A stent body that is made of a tubular, mesh-like braided metal wire and extends in an axial direction; a membrane body that circumferentially covers at least a portion of either the inner surface or the outer surface of the stent body; a constraining membrane disposed on a surface of the stent body opposite to the one surface thereof so as to sandwich the stent body between the membrane body and the constraining membrane, the constraining membrane being welded to at least a portion of the membrane body; wherein the welded portion between the membrane body and the restraining membrane is arranged to sandwich at least one wire portion of the metal wire, and is provided to avoid an intersection portion where two wire portions of the metal wire cross.

7. 7. The stent according to claim 6, wherein the restricting membrane is provided at least near both axial ends of the membrane body.

8. 8. The stent of claim 7, wherein the restraining membrane includes a first restraining membrane provided near the axial proximal end of the membrane body and a second restraining membrane provided near the axial distal end of the membrane body, the first restraining membrane and the second restraining membrane being spaced apart in the axial direction.

9. The stent according to any one of claims 1 to 8, further comprising a second stent body arranged so as to sandwich the membrane body between the stent body and a second stent body.

10. A stent body that is made of a tubular, mesh-like braided metal wire and extends in an axial direction; a membrane body circumferentially covering at least a portion of an outer surface of the stent body; a restraining membrane disposed on the inner surface of the stent body so as to sandwich the stent body between the membrane body and the restraining membrane, the restraining membrane being welded to only end regions of the membrane body in the axial direction; A stent comprising:

11. A stent body that is made of a tubular, mesh-like braided metal wire and extends in an axial direction; a membrane body circumferentially covering at least a portion of the inner surface of the stent body; a restraining membrane disposed on the outer surface of the stent body so as to sandwich the stent body between the membrane body and the restraining membrane, the restraining membrane being welded to only end regions of the membrane body in the axial direction; a second stent body disposed so as to sandwich the membrane body between the second stent body and the stent body; A stent comprising:

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