JP7051299B2 - Stent - Google Patents

Description

The present invention relates to a medical stent used for maintaining the inner diameter of an internal lumen in an expanded state by being expanded and placed in an internal lumen such as a blood vessel.

Conventionally, when an abnormality such as stenosis or occlusion occurs in a lumen such as a blood vessel, for example, a tubular stent is inserted into the stenosis site in the lumen to maintain the lumen in an expanded state. It has been. Examples of such a stent include a self-expandable stent that is exposed from the sheath and expands at body temperature after being delivered to a stenotic site in a reduced diameter state covered with a sheath by a stent delivery catheter, a balloon expansion stent that expands with a balloon, and the like. There is. Such a stent has a porous skeletal structure in which the peripheral wall of the stent is composed of struts having a large number of gaps (cells) so that the diameter can be reduced or expanded.

By the way, when the tissue forming the stenosis in the lumen is a soft porridge, the atheroma re-projects through the gap (cell) of the skeletal structure (strut) constituting the peripheral wall after the stent is placed, and the stent is placed. Restenosis may occur at the indwelling position of. Alternatively, the porridge that re-protrudes to the inner peripheral side of the stent may spread downstream of the stent placement position due to blood flow, and restenosis may occur downstream of the stent placement position.

As one of the measures against the problem of restenosis, it is conceivable to reduce the strut gap in the stent. However, if the gap between the struts is made small, the deformation rigidity of the stent becomes large, and for example, the expansion / contraction performance of the stent may be deteriorated, or the followability to the inner peripheral surface of a curved blood vessel may be deteriorated. there were.

On the other hand, Japanese Patent Application Laid-Open No. 11-299901 (Patent Document 1) proposes a stent (covered stent) with a cover covering the outer periphery of the strut constituting the stent body with a polymer film in which a plurality of micropores are perforated. Has been done. In the covered stent, the size of the strut gap can be reduced by using a soft polymer film, and the strut gap does not need to be reduced, so that the deformation rigidity of the strut can be suppressed to a small level.

However, in such a covered stent, when the stent is greatly expanded, the polymer film is stretched, so that cracks are generated at the periphery of the micropores and further grow, resulting in a large opening or tearing of the polymer film. There was a risk that it would end up. Therefore, when the expansion rate of the stent is large, for example, when the stent is placed in the carotid artery, there is a problem that it is difficult to stably exert the effect of the polymer film of miniaturizing the strut cell.

Japanese Unexamined Patent Publication No. 11-299901

The present invention has been made in the background of the above-mentioned circumstances, and the problem to be solved is that the miniaturization of the cell of the strut is stable even when the stent is greatly expanded while suppressing the increase in the deformation rigidity of the stent. The purpose is to provide a stent with a novel structure that can be realized.

The first aspect of the present invention is a stent in which a tubular cover layer is provided on a stent body having a skeletal structure that can be expanded and contracted, and the stent body extends in the circumferential direction while reciprocating in the axial direction. A plurality of annular bodies composed of shaped bodies are arranged in the length direction of the stent, and a plurality of unit cells having a substantially constant shape are formed at predetermined intervals in the circumferential direction between the annular bodies adjacent to each other in the length direction of the stent. At the same time, the annular bodies adjacent to each other in the length direction of the stent are connected by a connecting portion between the unit cells adjacent to each other in the circumferential direction, and the connecting portion is partially provided in the circumferential direction to form the connection. It is an open cell type skeletal structure in which a unit-cell structure divided by a portion and a continuous unit-cell structure without the connecting portion exist, while the cover layer is made of a knitted fabric and is also present. The cover layer is superposed so as to cover only the outer peripheral surface of the stent body, and the end of the cover layer is longer than the end of the stent body at at least one end in the length direction of the stent. It is characterized in that it is located inward in the direction and the end portion of the cover layer is fixed to the stent body by a fixing layer of an adhesive or a synthetic resin over one circumference in the circumferential direction.

According to the stent having a structure according to this aspect, the gap (cell) in the skeletal structure (strut) of the stent body can be miniaturized by covering the outer periphery of the stent body with a cover layer made of knitted fabric. Since the cover layer made of knitted fabric exhibits a greater expansion / contraction performance than the cover film or the like, even if the expansion rate at the time of placement after delivery of the stent is large, damage such as cracks in the cover layer is exhibited. Can be prevented and the target cell can be stably miniaturized.

Further, since the cover layer made of knitted fabric can obtain a flexible deformation performance as compared with the cover film or the like, excellent followability to the deformation of the strut can be exhibited. Therefore, it is possible to avoid a problem that the bending performance of the stent body is greatly deteriorated by the cover layer, and it is possible to realize a stable indwelling state by satisfactorily following and deforming a curved blood vessel or the like.

Furthermore, since the cover layer is overlapped so as to cover the outer periphery of the stent body, when the stent body is greatly bent and deformed in a bending shape, the bent portion in the skeletal structure of the stent body is locally on the outer peripheral side. It can also be suppressed from protruding into the stent.

Further, according to the stent having a structure according to this aspect, since the cover layer is fixed to the stent body at at least one end in the length direction, the cover is covered during delivery of the stent or after placement in the lumen. It prevents the layer and the stent body from being axially displaced from each other. Further, since the cover layer can be deformed more flexibly as compared with the case where the cover layer is fixed to the entire surface of the stent body, the flexible deformation performance of the stent can be more effectively ensured. Furthermore, according to the stent having a structure according to this aspect, since the skeletal structure of the stent body is an open cell type, connecting portions are provided in all of the unit cells adjacent to each other in the circumferential direction, and all of them are provided. Compared to the closed cell type skeletal structure, which is a unit cell with an independent structure, the stent body can be set more flexibly. In addition, when the open cell type stent body is curved and deformed, the non-connecting part of the linear body that easily protrudes locally to the outer peripheral side in the bending direction also has an effect of the amount of protrusion by the cover layer superimposed on the outer peripheral side of the stent body. Can be suppressed. In addition, according to the stent having a structure according to this embodiment, it is possible to easily form a fixed layer by, for example, immersing the end portion in the length direction in a solution of a synthetic resin and drying (dip) the stent. Therefore, mutual fixation between the stent body and the cover layer can be easily realized.

A second aspect of the present invention is the stent according to the first aspect, wherein the cover layer is fixed to the stent body in the circumferential direction at both ends in the length direction of the stent. be.

According to the stent having a structure according to this aspect, the relative axial misalignment between the stent body and the cover layer is efficiently displaced by fixing both ends in the length direction in which the amount of misalignment tends to be particularly large. It becomes possible to limit the target.

A fourth aspect of the present invention is that in the stent according to any one of the first to third aspects, the maximum stitch in the cover layer is smaller than the gap in the skeletal structure in the stent body. be.

According to the stent having a structure according to this embodiment, the maximum stitch in the cover layer is smaller than the gap in the skeletal structure in the stent body. Therefore, by superimposing the cover layer on the outer periphery of the stent body, the stent can be placed. The gaps in the skeletal structure in the body can be more reliably reduced.

According to the stent having a structure according to the present invention, the cover layer made of knitted fabric is superposed on the outer periphery of the stent body, so that the deformation performance of the stent is sufficiently ensured and the gap in the skeletal structure of the stent is small. can do.

The front view which shows typically the stent as the 1st Embodiment of this invention. The front view which shows the main part of the stent shown in FIG. 1 in the expanded state. It is a schematic diagram which expands and shows the main part of the stent as the 2nd Embodiment of this invention, and is the development view which cut open at a part of the circumference in the contraction state of a stent. Explanatory drawing for demonstrating the expanded state of the stent shown in FIG.

Hereinafter, in order to clarify the present invention in more detail, embodiments of the present invention will be described in detail with reference to the drawings.

First, FIG. 1 schematically shows a stent 10 as a first embodiment of the present invention. This stent 10 is a self-expandable stent, and is housed in a sheath provided in a stent delivery catheter in a reduced diameter state, delivered to a narrowed portion of a lumen such as a blood vessel, and then released from the sheath. When exposed to body temperature, the diameter is automatically expanded, and the stenotic part of the lumen is expanded and indwelled. In addition, in FIG. 1, the stent 10 is shown in a state where the diameter is neither reduced nor expanded. Further, in the following description, the length direction or the axial direction means the vertical direction in FIG. 1, which is the central axial direction of the stent 10.

More specifically, the stent 10 includes a stent body 12 and a tubular cover 14 as a tubular cover layer overlaid so as to cover the outer periphery of the stent body 12.

The stent main body 12 includes a substantially cylindrical peripheral wall portion 16 as a whole. In the present embodiment, one linear body 18 reciprocates in the axial direction and continuously extends over the entire circumference in the circumferential direction to form one annular body 20, and the plurality of annular bodies 20 form one annular body 20. By being connected by the connecting portion 22 as a connecting portion at an appropriate position in the circumferential direction, the plurality of annular bodies 20 are aligned in the axial direction to form the peripheral wall portion 16. That is, in the present embodiment, the strut 24 constituting the skeletal structure of the stent body 12 is composed of these linear bodies 18 (annular bodies 20) and the connecting portion 22. The cross-sectional shape of the strut 24 (linear body 18 and connecting portion 22) is not limited in any way, and in the present embodiment, it is a substantially rectangular cross-sectional shape, but it is a circle including an oval, an ellipse, and a semicircle. Various shapes such as a cross-sectional shape and a polygonal cross-sectional shape can be adopted.

As described above, in the annular body 20, the linear body 18 reciprocates in the axial direction and continuously extends over the entire circumference in the circumferential direction, and is formed into a wavy shape that repeats a substantially constant periodic structure. There is. That is, in the state of FIG. 1, the linear body 18 has a straight portion 26 extending linearly in the substantially axial direction, a curved portion 28a convex in one axial direction (upper in FIG. 1), and the other in the axial direction ( It has a curved portion 28b that is convex at the lower side in FIG. 1). Then, in the linear body 18, the linear portion 26 and the curved portions 28a and 28b are alternately continuous to form the annular body 20.

In the present embodiment, the annular bodies 20 and 20 adjacent in the axial direction are positioned so as to be offset from each other by 1/2 cycle in the circumferential direction. That is, in the annular bodies 20 and 20 adjacent in the axial direction, the curved portion 28a that is convex in one axial direction and the curved portion 28b that is convex in the other axial direction face each other in the axial direction. The curved portions 28a and the curved portions 28b facing each other in the axial direction are connected by a connecting portion 22 extending in the axial direction, so that the annular bodies 20 and 20 adjacent in the axial direction are connected to each other.

That is, a substantially annular gap 30 extending continuously over the entire circumference in the circumferential direction is formed between the annular bodies 20 and 20 adjacent in the axial direction, and the gap 30 has a large axial dimension and a small portion. The parts are alternately repeated in the circumferential direction. The gap 30 is divided in the circumferential direction at the position where the connecting portion 22 is formed. In other words, between the annular bodies 20 and 20 adjacent in the axial direction, a plurality of gaps 32 as unit cells surrounded by the curved portions 28a and 28b and the straight portion 26 are formed with a substantially constant shape. A plurality of gaps 32 are continuous with each other at predetermined intervals in the circumferential direction to form a gap 30. In the present embodiment, each gap 32 constitutes a gap of the strut (skeletal structure) 24 constituting the stent main body 12.

In the present embodiment, in the annular bodies 20 and 20, not all of the curved portions 28a and 28b facing each other are connected by the connecting portion 22, but the peripheral portions of the curved portions 28a and 28b facing each other are circumscribed. It is connected by the connection portion 22 at one place or a plurality of places of the above. In short, in the present embodiment, a plurality of gaps (unit cells) 32 communicate with each other in the circumferential direction via curved portions 28a and 28b facing each other, and the stent main body 12 has an open cell type skeletal structure. Has been done. In other words, in the stent main body 12 of the present embodiment, a portion having a unit cell-to-unit structure in which the unit cells 32 and 32 adjacent to each other in the circumferential direction are divided by a connecting portion (connecting portion) 22 and a connecting portion (connecting portion). The connecting portion) 22 is not provided, and the unit cells 32, 32 adjacent to each other in the circumferential direction have a portion having a mutually continuous unit cell-to-unit structure.

The stent body 12 having such a shape has a skeletal structure that can be expanded and contracted. That is, the stent body 12 is made of a material that exerts a shape memory effect, such as a Ni—Ti alloy, and exhibits superelasticity (pseudoelasticity) at body temperature, and is heat-treated in an expanded state. By doing so, the shape of the expanded state is stored. As a result, the stent body 12 is inserted into a sheath or the like (not shown) in a contracted state, is maintained in the contracted shape, is delivered to the vicinity of the narrowed portion of the internal lumen, and is extruded from the sheath. It is a self-expanding stent that automatically restores to the dilated shape at the stenotic site when the restraint is released. Such a stent body 12 includes, for example, an annular body 20 provided with a straight portion 26 and curved portions 28a, 28b, obtained by cutting a thin tubular member made of Ni—Ti alloy with a laser. It can be obtained by integrally forming a connecting portion 22 connecting them. However, the method for manufacturing the stent body 12 is not limited to laser cutting as described above, and conventionally known methods for manufacturing a stent, such as electroforming and etching, can be adopted.

On the other hand, the tubular cover 14 superposed on the outer periphery of the stent main body 12 as described above includes a substantially tubular peripheral wall portion 34 as a whole, and the peripheral wall portion 34 has one or a plurality of strands 36. It is formed by knitting (braiding) into a tubular shape. That is, in the present embodiment, the entire tubular cover (cylindrical cover layer) 14 is made of knitted fabric. Although the tubular cover 14 is shown in a mesh shape in FIG. 1, it merely schematically shows that the tubular cover 14 is formed by braiding the strands 36, and is merely a tubular cover. The structure of 14 is not limited in any way.

The axial dimension of the tubular cover 14 is not limited in any way, but in the present embodiment, it is shorter than the stent main body 12, and particularly in the present embodiment, it is located at the outermost position in the axial direction of the stent main body 12. The size of the annular body (the annular body located at the upper end and the lower end in FIG. 1) 20 and 20 is set.

Further, the inner diameter of the tubular cover 14 in the single item state before being superposed on the stent body 12 is not limited in any way, but may be substantially equal to the outer diameter of the stent body 12 shown in FIG. It is preferable, and more preferably, it is made smaller than the outer diameter dimension of the stent body 12. In particular, when the tubular cover 14 has elasticity, the inner diameter of the tubular cover 14 is made smaller than the outer diameter of the stent body 12, so that the tubular cover 14 is superposed on the outer periphery of the stent body 12. At that time, it is possible to reduce the possibility that the stent body 12 and the cylindrical cover 14 are displaced in the axial direction due to the urging force that tends to reduce the diameter of the tubular cover 14 toward the inner peripheral side.

Further, as the material of the wire 36 constituting the tubular cover 14, for example, synthetic resins such as polyolefin-based, polyester-based, polyamide-based, and polyurethane-based, and metals such as Ni—Ti alloy and stainless steel are preferably adopted. In this embodiment, it is formed of polyethylene terephthalate (PET). The cross-sectional shape of the wire 36 is not limited in any way, and although it is a circular cross-sectional shape in the present embodiment, various cross-sectional shapes such as an ellipse, an oval, a semicircle, and a polygonal cross-sectional shape of a triangle or more can be used. Can be adopted. Further, the outer diameter dimension of the wire 36 is not limited in any way, but in the present embodiment, it is smaller than the width dimension of the strut 24 constituting the stent main body 12, and is braided to form the tubular cover 14. At the same time, the diameter can be expanded or reduced in the radial direction.

Further, the braiding method of the wire 36 is not limited in any way, but when the tubular cover 14 is braided, the diameter can be freely expanded or reduced according to the expansion / contraction deformation of the stent body 12. Knitted fabric (flat knitting, tenjiku knitting), rubber knitting (rib knitting), pearl knitting, weft knitting change organization (tack, mistake, transfer, pile knitting, splicing thread, lace knitting, etc.), Conventionally known braiding methods such as Denby (tricot), Bandaik (atlas), cord, warp knitting change structure (lap, swing, thread pulling, etc.) can be adopted. In the present embodiment, the knitted fabric is adopted, and the strands 36 are braided into a cylindrical shape by the knitted fabric, so that there are innumerable gaps 38 as stitches having a size substantially equal to the peripheral wall portion 34 of the tubular cover 14. Is formed in.

The size of the gap (stitch) 38 formed by the strands 36 is not limited in any way, but in the present embodiment, the state shown in FIG. 1, that is, the tubular cover on the outer periphery of the stent main body 12. The gap (stitch) 38 is made smaller than the gap 32 formed in the strut 24 in the stent body 12 in the state where the 14s are overlapped and the diameter is not reduced or expanded. However, the size of the gaps (stitches) formed by the strands may differ from each other in some sizes, but even the largest gaps (stitches) have a skeletal structure in the stent body. It is preferable that the gap is smaller than the gap of.

At both ends of the tubular cover 14 in the axial direction, the ends of the strands 36 may or may not be fixed (end treatment) by adhesion or welding between the strands 36.

As shown in FIG. 2, the tubular cover 14 having the above structure is extrapolated to the stent main body 12 and partially fixed to the stent main body 12 at a plurality of axially separated points. Is desirable. In the present embodiment, both ends of the tubular cover 14 in the axial direction are fixed to the stent body 12 partially or intermittently in the circumferential direction or continuously over the entire circumference. The fixing method for fixing the tubular cover 14 to the stent main body 12 is not limited in any way, but in the present embodiment, both ends in the longitudinal direction of the stent 10 are made of synthetic resin. It is fixed to the stent body 12 via a fixing layer 40, 40 made of the same.

That is, in the present embodiment, in a state where the tubular cover 14 is externally inserted into the stent main body 12, both ends in the length direction of the stent 10 are immersed in a synthetic resin solution and dried (dipped) to dry (dip) the tubular cover 14. An annular fixed layers 40, 40 made of synthetic resin are formed at both ends in the axial direction of the stent, and the tubular cover 14 is fixed to the stent main body 12 via the fixed layers 40, 40.

As described above, when the tubular cover 14 is fixed to the stent body 12 by dipping, the synthetic resin constituting the fixing layers 40 and 40 is not particularly limited, but for example, polyurethane, polyester, etc. Vinyl chloride and the like are preferably used, and polyurethane is used in this embodiment.

However, the fixing direction of the tubular cover 14 to the stent body 12 is not limited to the one by dipping as described above, and the fixing layers 40 and 40 are formed by the adhesive, that is, the tubular cover 14 is formed by the adhesive. It may be fixed to the stent body 12. Further, one of the tubular covers 14 in the axial direction may be fixed to the stent body 12 by dipping, and the other in the axial direction may be fixed with an adhesive.

The axial dimensions of the fixed layers 40 and 40 are not limited in any way, but in the present embodiment, the annular body located on the outermost side in the axial direction (the annular body located at the upper end and the lower end in FIG. 1). Body) The fixed layers 40 and 40 are formed over substantially the entire axial length of the 20 and 20, that is, at both ends of the stent 10 in the axial direction and around the circumferential direction. The stent body 12 and the tubular cover 14 need only be fixed over at least one circumference in the circumferential direction, and when the fixing layer 40 is provided as in the present embodiment, the axial dimension of the fixing layer 40 is provided. Is preferably 1 to 10% of the total length of the stent 10.

The stent 10 having the above structure is attached to the stent delivery catheter in a reduced diameter state and is housed in the sheath. Then, after the stent delivery catheter is delivered to the stenotic part of the lumen such as a blood vessel, the stent 10 is released from the sheath to automatically expand to the expanded state and expand the stenotic part of the lumen. It has become like.

In the stent 10 of the present embodiment, the tubular cover 14 made of knitted fabric is overlapped from the outer periphery of the stent body 12, so that the gap 32 of the skeletal structure in the stent body 12 is reduced, and the lumen is re-stenotic. Can be effectively prevented. In particular, since the tubular cover 14 is made of a knitted fabric, it follows the expansion / contraction deformation and bending deformation of the stent body 12 as compared with the film-shaped tubular cover as described in Patent Document 1, for example, and has a tubular shape. Even when the cover 14 can be deformed more flexibly and the stent 10 is greatly expanded, the gap 38 provided in the tubular cover 14 becomes too large and the tubular cover 14 is cracked or cracked. Further, problems such as tearing of the tubular cover 14 can be effectively prevented.

Further, in the present embodiment, since the gap (stitch) 38 in the tubular cover 14 is smaller than the gap 32 in the skeletal structure in the stent main body 12, the stent main body is formed by superimposing the tubular cover 14 and the stent main body 12. The gap 32 of the skeletal structure in 12 can be made smaller more reliably.

Further, in the present embodiment, both ends of the tubular cover 14 in the axial direction are fixed to the stent main body 12 via fixing layers 40 and 40 made of synthetic resin. The fixed layers 40, 40 can be easily formed by, for example, immersing both side portions of the stent body 12 in the length direction in a synthetic resin solution and drying (dip) the stent body 12, and the stent body 12 and the cylinder. Mutual fixation with the shape cover 14 can be easily realized. By fixing both ends of the tubular cover 14 in the axial direction to the stent main body 12 in this way, the axial misalignment between the stent main body 12 and the tubular cover 14 can be prevented. Further, the stent 10 can be flexibly deformed as compared with the case where the tubular cover 14 is fixed to the stent main body 12 over the entire surface.

In particular, since the tubular cover 14 is made of a knitted fabric, it is preferable that the strands 36 are mutually fixed (end-treated) by adhesion or welding at both ends in the axial direction. By fixing both ends in the axial direction to the stent main body 12, the work of end treatment as described above can be omitted.

Further, in the present embodiment, the stent body 12 has an open cell type skeletal structure, that is, since a plurality of unit cells (gap) 32 are communicated with each other in the skeletal structure of the stent body 12, the stent 10 The flexibility of the skeleton is improved, and the expansion and contraction of the diameter and the bending deformation can be easily realized. In particular, since the stent main body 12 has an open cell type skeletal structure, for example, when the stent main body 12 is flexed and deformed, the curved portions 28a and 28b that are not connected by the connecting portion 22 tend to protrude toward the outer peripheral side. By covering the outer periphery of the stent body 12 with the tubular cover 14, local protrusion of the stent body 12 can be effectively prevented.

Next, FIGS. 3 and 4 show the stent 50 as the second embodiment of the present invention in a contracted state (FIG. 3) and an expanded state (FIG. 4). In the present embodiment, the positions of the connecting portions (connecting portions) connecting the annular bodies 20 and 20 adjacent in the axial direction are different from those in the first embodiment. It should be noted that FIGS. The illustration is omitted because it can be done. However, the structure of both ends in the axial direction of the stent 50 may be different from that of the first embodiment. For example, the connecting portion (connecting portion) connecting the annular bodies 20 and 20 extends over the entire circumference in the circumferential direction. May be continuously provided. Further, in the present embodiment, the members and parts substantially the same as those of the first embodiment are designated by the same reference numerals as those of the first embodiment in the drawings, whereby detailed description thereof will be omitted. ..

That is, in the present embodiment, as shown in FIG. 3, the connecting portions 52 as two or three connecting portions are adjacent to each other in the circumferential direction. As a result, in the present embodiment, as shown in FIG. 4, among the gaps (unit cells) 56 formed in the skeletal structure of the stent main body 54, the positions are located between the connecting portions 52 and 52 adjacent in the circumferential direction. The gap (unit cell) 56 is closed (closed) by being surrounded by a straight portion 26, curved portions 28a, 28b, and connecting portions 52, 52 of the linear body 18. On the other hand, the gap (unit cell) 56 that is not located between the connecting portions 52 and 52 that are adjacent in the circumferential direction communicates with at least one of the gaps (unit cells) 56 that are adjacent in the circumferential direction, that is, in the circumferential direction. It is open to at least one side. Therefore, also in the stent main body 54 of the present embodiment, the unit cells 56 and 56 adjacent to each other in the circumferential direction have a unit cell-to-unit structure divided by the connecting portion (connecting portion) 52 and the connecting portion (connecting portion). Part) 52 is not provided, and the adjacent unit cells 56 and 56 in the circumferential direction have a portion having a mutually continuous unit cell-to-unit structure, and the skeleton structure thereof is an open cell type. There is.

Even in the stent 50 having the above-mentioned structure, as in the first embodiment, the tubular cover 14 as a cover layer is overlapped on the outer periphery of the stent main body 54 so as to cover the stent body 54. The same effect as that of the embodiment can be exhibited.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited by the specific description thereof.

For example, in the stents 10 and 50 of the above-described embodiment, one linear body 18 constitutes one annular body 20, and the annular body 20 has a structure in which a plurality of the annular bodies 20 are connected by connecting portions 22, 52. However, one linear body may be configured to extend spirally in the circumferential direction, that is, the peripheral wall portion of the stent body may be configured by one linear body. Therefore, in the stent body in the present invention, the cell formed by being surrounded by the skeletal structure is not essential.

Further, the stent bodies 12 and 54 of the above embodiment have an open cell type skeletal structure, but in the skeletal structure of the stent body, all the gaps (unit cells) are linear portions and curved portions. It may be a closed type skeletal structure closed by a connection.

Further, the stents 10 and 50 of the above-described embodiment are all self-expandable stents due to shape memory action, but they are attached to a balloon catheter and delivered to the stenosis site, and are expanded by the balloon at the stenosis site. It may be a balloon-expandable stent.

Further, in the above-described embodiment, the axial dimension of the tubular cover 14 is shorter than the axial dimension of the stent bodies 12 and 54, but the present invention is not limited to this aspect, and the cover layer (cylindrical cover). The axial dimension of the stent body may be substantially equal to the axial dimension of the stent body, or may be longer than the axial dimension of the stent body.

Further, in the above-described embodiment, the fixing layers 40, 40 for fixing the tubular cover 14 to the stent main bodies 12, 54 are formed over the entire length in the circumferential direction, but the present invention is not limited to this embodiment. It may be partially formed on.

Further, in the above embodiment, the entire tubular cover 14 is made of knitted fabric, but the cover layer (cylindrical cover) may have at least a part of the knitted structure. That is, for example, the portion fixed to the stent body does not have to have a knitted structure, and in the case of the above embodiment, both ends in the axial direction may extend in the axial direction without braiding, for example, the strand 36. ..

Furthermore, in the above embodiment, the stitch (gap) 38 in the tubular cover 14 is smaller than the gap (unit cell) 32 in the skeletal structure of the stent bodies 12 and 54, but the cover layer (cylinder). The size of the stitches in the shape cover) may be larger than the gap (unit cell) in the skeletal structure of the stent body.

Further, by superimposing the cover layer on the outer periphery of the stent body, it is not necessary to reduce all the gaps (unit cells) in the skeletal structure of the stent body, and the gaps (unit cells) in the skeletal structure of the stent body are not required to be reduced. At least one of them may be reduced.

10,50: Stent, 12,54: Stent body, 14: Cylindrical cover (cover layer), 24: Strut (skeletal structure), 32,56: Skeletal structure gap (unit cell) in the stent body, 38: Cover Gap in the layer (stitch)

Claims (3)

A stent with a tubular cover layer provided on the stent body, which has a skeletal structure that can be expanded and contracted.
A plurality of annular bodies composed of linear bodies extending in the circumferential direction while reciprocating in the axial direction of the stent body are arranged in the length direction of the stent, and are substantially constant between the annular bodies adjacent to each other in the length direction of the stent. A plurality of unit cells having a shape are formed at predetermined intervals in the circumferential direction, and the annular bodies adjacent in the length direction of the stent are connected between the unit cells adjacent in the circumferential direction by a connecting portion. By partially providing the connecting portion in the circumferential direction, it is an open cell type skeleton structure in which an inter-unit cell structure divided by the connecting portion and a continuous inter-unit cell structure without the connecting portion exist. On the other hand
The cover layer is made of knitted fabric, and the cover layer is overlapped so as to cover only the outer peripheral surface of the stent body.
At at least one end in the length direction of the stent, the end of the cover layer is located inward in the length direction with respect to the end of the stent body, and the end of the cover layer is the stent body. A stent characterized in that it is fixed by a fixing layer of an adhesive or a synthetic resin over one circumference in the circumferential direction. The stent according to claim 1, wherein the cover layer is fixed to the stent body in the circumferential direction at both ends in the length direction of the stent. The stent according to claim 1 or 2 , wherein the maximum stitch in the cover layer is smaller than the gap in the skeletal structure in the stent body.

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