JP6955679B2 - Stent - Google Patents

Description

The present invention relates to a stent that is inserted 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 stent treatment is performed in which a tubular stent is inserted into the stenosis site in the lumen to keep the lumen in an expanded state. ing. Such a stent is, for example, delivered to a stenotic site in a reduced diameter state covered with a sheath by, for example, a stent delivery catheter, and then automatically restored to a enlarged diameter state by being exposed from the sheath and exposed to body temperature. There are self-expanding stents and the like. Since such a stent is inserted into the sheath in a reduced diameter state, the peripheral wall of the stent has a porous structure such as a mesh so that it can be contracted and deformed.

By the way, when the tissue forming the stenosis is a soft porridge, the porridge may re-protrude through the pores of the peripheral wall after the stent is placed, and restenosis may occur at the position where the stent is placed. Alternatively, the porridge that re-protrudes to the inner peripheral side of the stent may spread to the downstream of the stent placement position due to blood flow, and restenosis may occur downstream of the stent placement position.

Therefore, for example, it is conceivable to reduce the size of the pores by increasing the number of a plurality of strands constituting the mesh-like peripheral wall in the stent.

However, in a stent, since the maximum diameter in a reduced diameter state is limited for the purpose of insertion into a sheath or the like, the wire diameter of the wire must be reduced in order to increase the number of wires. Therefore, there is a risk that the expanding force required for the self-expandable stent cannot be sufficiently obtained.

In FIG. 12 of Japanese Patent Application Laid-Open No. 2014-513987 (Patent Document 1), a coarse mesh outer layer sleeve made of a large diameter wire is overlapped with a fine mesh inner sleeve made of a small diameter wire. In addition, a double-sleeve stent in which these inner and outer separate sleeves are connected to each other at the end in the length direction has been proposed.

However, in a stent having such a double-sleeve structure, the inner layer sleeve and the outer layer sleeve are easily separated from each other, and especially when placed in a curved part of a blood vessel, the inner layer sleeve and the outer layer sleeve have different deformation strengths. Large gaps are likely to occur between the sleeves. When such a gap is generated, the inner layer sleeve may float in the blood vessel to obstruct the flow of blood, or thrombus may adhere to the stent to cause restenosis.

Special Table 2014-513987

The present invention has been made in the background of the above circumstances, and the problem to be solved is that it is possible to secure a sufficient expanding force while reducing the size of the pores formed in the peripheral wall, and the lumen. The purpose is to provide a stent with a new structure that can suppress the lifting from the surface.

Hereinafter, aspects of the present invention made to solve such problems will be described. The components adopted in each of the following aspects can be adopted in any combination as much as possible.

In the first aspect of the present invention, a single-layer peripheral wall is formed of a composite structure in which strands having different expansion forces and small expansion forces and strands having large expansion forces are woven or braided with each other. The pores formed by the wire having a small expanding force are smaller than the pores formed by the wire having a large expanding force on the peripheral wall, and the end in the length direction on the peripheral wall. In the portion, the end of the wire having a large expanding force wound in one direction in the circumferential direction and the end of the wire having a large expanding force wound in the other direction in the circumferential direction are in the length direction. The stent is characterized in that it has a flare structure that expands to the outer peripheral side as it becomes outward in the length direction on the peripheral wall by being connected via an end member having a folded portion in the middle portion of the above.

According to the stent having a structure according to this embodiment, the small pores formed by the strands having a small expanding force effectively prevent the tissue forming the stenosis from protruding into the stent. Further, since the wire having a large expansion force is woven or braided with respect to the wire having a small expansion force, the wire having a large expansion force can sufficiently secure the expansion force of the stent.

In particular, since the peripheral wall of a single layer is formed by these strands having a large expanding force and the strands having a small expanding force, when the stent is placed in a curved portion of the lumen like the stent described in Patent Document 1. There is no separation between the inner layer and the outer layer. Further, since the wire having a large expansion force and the wire having a small expansion force are fixed by weaving or braiding each other, it is not necessary to separately provide a member or the like for connecting the two wires to each other. In addition, according to the stent having a structure according to this aspect, since the end has a loop structure, when the stent is placed in the lumen, the end may pierce the wall surface of the lumen. The risk can be reduced.
Further, in the second aspect of the present invention, in the stent according to the first aspect, the end member is connected to the wire having a large expanding force by a connecting member.

A third aspect of the present invention is that in the stent according to the first or second aspect, at least one of the material and the thickness of the wire having a large expanding force and the wire having a small expanding force are different. It is something that is.

According to the stent having a structure according to this aspect, for example, a wire having a large expansion force has a larger diameter than a wire having a small expansion force, or a hard material is used as the material of the wire. By doing so, it can be easily formed.

In a fourth aspect of the present invention, in the stent according to any one of the first to third aspects, the number of strands having a large expanding force is reduced as compared with the strands having a small expanding force. Is what you are doing.

According to the stent having a structure according to this aspect, the number of strands having a large expanding force can be reduced as compared with the strands having a small expanding force, so that, for example, the distance between the strands having a large expanding force can be increased. As a result, the pores formed by the wire having a large expanding force can be made larger than the pores formed by the wire having a small expanding force. In addition, if the number of wires with a large expansion force is too large, the stent may become too stiff. Therefore, by reducing the number of wires with a large expansion force compared to the wires with a small expansion force, the stent may become too stiff. Moderate flexibility can be obtained.

In a fifth aspect of the present invention, in the stent according to any one of the first to fourth aspects, a plurality of strands composed of the strand having a small expanding force and the strand having a large expanding force are formed. The strands are arranged in a spiral shape in opposite directions, and the strands formed in a spiral shape in opposite directions are woven so as to be woven inside and outside the layer constituting the peripheral wall to form a single layer. As a result, a single-layer peripheral wall having the composite structure is formed.

According to the stent having a structure according to this embodiment, for example, a wire having a large expansion force and a wire having a small expansion force are woven in a spiral shape in opposite directions, so that the peripheral wall of the stent has a mesh shape. Therefore, the size of the pores can be made smaller.

A sixth aspect of the present invention is that in the stent according to any one of the first to fifth aspects, a plurality of strands having a small expanding force are arranged in a spiral shape in opposite directions to each other. The wires having a small expansion force, which are spiral in the opposite direction, are woven so as to be woven inside and outside the layer constituting the peripheral wall, while the wires having a large expansion force are woven in at least one direction. At least one wire is arranged in a spiral shape, and the wire having a large expansion force is woven so as to be woven inside and outside the layer constituting the peripheral wall with respect to the wire having a small expansion force to form a single layer. By constructing the above, a single-layer peripheral wall having the above-mentioned composite structure is formed.

According to the stent having a structure according to this embodiment, since the strands having a small expanding force spiraling in opposite directions are also woven together, the pores are small due to these plurality of strands having a small expanding force. A mesh-like peripheral wall can be stably formed.

A seventh aspect of the present invention is that in the stent according to the fifth or sixth aspect, the strands including the strands having a large expanding force and the strands having a small expanding force are as a whole at equal intervals and the same. It is woven with a lead angle.

According to the stent having a structure according to this aspect, the strands having a large expanding force and the strands having a small expanding force are woven as a whole at equal intervals and at the same lead angle, so that, for example, the expanding force is large. It is also possible to weave a wire and a wire with a small expansion force by a machine at the same time. In particular, since the wire having a large expansion force and the wire having a small expansion force are woven at the same lead angle, the stent can be contracted substantially evenly over the entire circumference when the diameter of the stent is reduced. Therefore, when the stent is inserted into the sheath or the like, the possibility that a part of the stent protrudes to the outer peripheral side and is caught by the sheath or the like can be reduced.

In the eighth aspect of the present invention, a single-layer peripheral wall is formed of a composite structure in which strands having different expansion forces and small expansion forces and strands having large expansion forces are woven or braided with each other. In the peripheral wall, the pores formed by the wire having a small expansion force are smaller than the pores formed by the wire having a large expansion force, while the wire having a small expansion force is smaller. , A plurality of wires having spirals in opposite directions are arranged, and the strands having small expansion forces spiraling in opposite directions are woven so as to be woven inside and outside the layer constituting the peripheral wall. At the same time, at least one wire having a large expansion force is arranged in a spiral shape in at least one direction, and the wire having a large expansion force is the peripheral wall of the wire having a small expansion force. By forming a single layer by being woven so as to be woven inside and outside the layers constituting the above, the peripheral wall of the single layer made of the composite structure is formed, and the expansion force of the strands is formed. The stent is characterized in that the lead angle formed only by the wire having a large expansion force is larger than the lead angle formed only by the wire having a small expansion force.

According to the stent having a structure according to this embodiment, the lead angle of the wire having a large expansion force is different from the lead angle of the wire having a small expansion force. After forming the peripheral wall, it is also possible to weave a wire having a large expanding force on the peripheral wall formed by the wire having a small expanding force in a spiral shape in the opposite direction by the technique of the manufacturer. In particular, by making the lead angle of the wire with a large expansion force larger than the lead angle of the wire with a small expansion force, it is formed by the wire having a larger expansion force than the pores formed by the wire with a smaller expansion force. The size of the pores can be increased more easily.

According to the stent having a structure according to the present invention, the reduction size and expansion required by newly adopting a single-layer peripheral wall having a composite structure of a wire having a small expansion force and a wire having a large expansion force. The force can be advantageously realized, and delamination of the peripheral wall under the indwelling state can be prevented.

The front view which shows the whole of 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 an enlarged manner. A front view showing an enlarged end of the stent shown in FIG. The front view which shows the whole of the stent as the 2nd Embodiment of this invention. The front view which shows the main part of the stent shown in FIG. 4 in an enlarged manner. The front view which shows the whole of the stent as the 3rd Embodiment of this invention. FIG. 6 is an enlarged front view showing a main part of the stent shown in FIG. The front view which shows the whole of the stent as the 4th Embodiment of this invention. FIG. 8 is an enlarged front view showing a main part of the stent shown in FIG. Front view showing another aspect at the end of the stent shown in FIG. Front view showing yet another aspect at the end of the stent shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First, FIGS. 1 to 3 show a stent 10 as a first embodiment of the present invention. The stent 10 is a self-expanding stent. For example, the stent 10 is inserted into a sheath provided in a stent delivery catheter in a reduced diameter state to be delivered to a stenosis in an internal lumen such as a blood vessel, and then from the sheath. When exposed to body temperature, it automatically expands and deforms to expand the stenosis. In addition, in FIGS. 1 to 3, the stent 10 is shown in a state where the diameter is neither reduced nor expanded. Further, in the following description, the axial direction means the left-right direction in FIG. 1 which is the central axial direction of the stent 10.

More specifically, the axially intermediate portion of the stent 10 is generally tubular or substantially tubular with a single layer peripheral wall 12 and extends linearly. The peripheral wall 12 is configured as a composite structure in which a plurality of types of strands 14 having different expansion forces are woven or braided with each other. The expanding force is interpreted as the stress that elastically restores and deforms in the expanding direction while the stent is reduced in diameter and attached to the catheter.

In the present embodiment, the expansion force is made different by making the thickness of the wire 14 different, and the large diameter wire 16 having a large outer diameter is adopted as the wire having a large expansion force, while the expansion force is small. A small-diameter wire 18 having a small outer diameter is used as the wire. That is, the wire 14 forming the peripheral wall 12 is composed of the large diameter wire 16 and the small diameter wire 18.

Both the large-diameter wire 16 and the small-diameter wire 18 have a substantially circular cross-sectional shape, and extend in the length direction with a substantially constant thickness. Incidentally, as the stent for blood vessels, for example, it is preferable that the outer diameter dimension of the large diameter wire 16 is 150 μm to 300 μm, while the outer diameter dimension of the small diameter wire 18 is 20 μm to 60 μm. Further, these large-diameter wire 16 and small-diameter wire 18 have substantially the same length dimension in the present embodiment in which the lead angles are substantially equal as described later, and are large over the total length in the axial direction of the peripheral wall 12. The diameter wire 16 and the small diameter wire 18 are integrally woven into a single structure. Then, both ends in the axial direction of the large-diameter wire 16 and both ends in the axial direction of the small-diameter wire 18 are set at substantially equal axial positions.

It should be noted that the wire with a large expansion force and the wire with a small expansion force do not need to exert the expansion force in the single state before weaving or braiding, and are woven or braided to form a peripheral wall, and when used. It suffices if the diameter is reduced so that a large or small expanding force can be exerted. However, since the expanding force in the peripheral wall structure generally corresponds to the bending strength or bending elasticity in the single wire state, it is also possible to adopt a wire having a large bending strength or bending elasticity and a wire having a small bending elasticity in the single wire state. It is possible.

A plurality of such large-diameter strands 16 are provided, and each of them has a spiral shape and extends in the axial direction. That is, in the axial projection of the stent 10 (for example, when viewed from the left to the right in FIG. 1), the large-diameter wire 16a spirally wound in one direction (for example, clockwise) in the circumferential direction. , A plurality of large-diameter strands 16b that are spirally wound in other directions (for example, counterclockwise) in the circumferential direction are provided. In the present embodiment, the same large-diameter wire 16a wound in one direction in the circumferential direction and the large-diameter wire 16b wound in the other direction in the circumferential direction are provided.

On the other hand, a plurality of small-diameter strands 18 are also provided, and each of them has a spiral shape and extends in the axial direction. That is, in the axial projection of the stent 10, there are a plurality of small-diameter strands 18a spirally wound in one direction in the circumferential direction and a plurality of small-diameter strands 18b spirally wound in the other direction in the circumferential direction. Books are provided one by one. The number of these small diameter wires 18a and 18b is larger than the number of large diameter wires 16a and 16b, respectively. In this embodiment, the same number of small diameter wires 18a and 18b (18 wires) are provided. ..

The large-diameter strands 16a and 16b and the small-diameter strands 18a and 18b having spiral shapes in opposite directions are woven together to form a single-layer peripheral wall 12. In the present embodiment, the large-diameter strands 16a and 16b and the small-diameter strands 18a and 18b are mechanically and simultaneously woven by, for example, an automatic loom.

_{In particular, in the present embodiment, the pitches (axial spacing) A 1} (see FIG. 1) of the large-diameter strands 16a, 16a (16b, 16b) adjacent in the axial direction are substantially equal to each other, and in the axial direction. _{The pitches B 1} (see FIG. 2) of the adjacent small-diameter strands 18a and 18a (18b, 18b) are substantially equal to each other. Since the number of small diameter wires 18a and 18b is larger than the number of large diameter wires 16a and 16b, the diameter is smaller than _{the pitch A 1 of the large diameter wires 16a and 16a (16b and 16b). The pitch B 1} of the strands 18a, 18a (18b, 18b) is smaller (B ₁ <A ₁ ).

_{Further, since B 1} <A ₁ as described above, in the stent of the present embodiment, the ratio to the total length of the arranged large-diameter strands 16a (16b) per unit length of the peripheral wall. Therefore, the total length of the arranged small-diameter strands 18a (18b) is longer.

_{Then, the pitch B 1 of} the small diameter wires 18a, 18a (18b, 18b) _{adjacent in the axial direction and the pitch C 1 of} the large diameter wires 16a (16b) and the small diameter wires 18a (18b) adjacent in the axial direction. (See FIG. 2) is almost equal (B ₁ = C ₁ ). Therefore, in the present embodiment, the strands 14 (large diameter strands 16a, 16b and small diameter strands 18a, 18b) constituting the peripheral wall 12 are substantially equally spaced (equal pitch) as a whole over a substantially total length in the axial direction. ) Is woven.

_{Further, the lead angles α a} (see FIG. 2) of the large-diameter wire 16a wound in one direction in the circumferential direction are substantially equal to each other, and the large-diameter wire wound in the other direction in the circumferential direction is substantially equal to each other. The lead angles α _b (see FIG. 2) of the wire 16b are also substantially equal to each other. Then, the magnitudes of these lead angles α _{a and α b} are substantially equal (| α _a | = | α _b |).

_{Further, the lead angles β a} (see FIG. 2) of the small diameter wires 18a wound in one direction in the circumferential direction are substantially equal to each other, and the small diameter wires 18b wound in the other direction in the circumferential direction are substantially equal to each other. The lead angles β _b (see FIG. 2) of the above are substantially equal to each other. Then, the magnitudes of these lead angles β _{a and β b} are substantially equal (| β _a | = | β _b |).

Furthermore, in the present embodiment, the sizes of the lead angles α _a , α _b , β _a , and β _b of the large-diameter strands 16a and 16b and the small-diameter strands 18a and 18b are substantially equal (| α _a | = | α _b | = | β _a | = | β _b |). Therefore, in the present embodiment, the strands 14 (large diameter strands 16a, 16b and small diameter strands 18a, 18b) constituting the peripheral wall 12 are woven with substantially the same lead angle as a whole over a substantially total length in the axial direction. It is made.

In the present embodiment, the large-diameter strands 16a and 16b and the small-diameter strands 18a and 18b are woven by plain weave. That is, for example, the large-diameter wire 16a wound in one direction in the circumferential direction is on the outer peripheral side and the inner peripheral side with respect to the large-diameter wire 16b and the small-diameter wire 18a, 18b wound in the other direction in the circumferential direction. That is, they are woven so as to be alternately woven inside and outside the layers constituting the peripheral wall 12. Similarly, for example, a layer in which a small-diameter wire 18a wound in one direction in the circumferential direction constitutes a peripheral wall 12 with respect to a small-diameter wire 18b and a large-diameter wire 16a, 16b wound in the other direction in the circumferential direction. It is woven so that it is woven alternately inside and outside. However, the weaving method of these large-diameter strands and small-diameter strands is not limited in any way, and conventionally known weaving methods such as twill weave and satin weave can be adopted.

Here, the large-diameter strands 16a and 16b wound in opposite directions are woven together to form mesh-shaped pores 20 by the large-diameter strands 16a and 16b. On the other hand, the small-diameter strands 18a and 18b wound in opposite directions are woven together to form mesh-shaped pores 22 by the small-diameter strands 18a and 18b. _{Here, the pitch B 1} of the small diameter wires 18a, 18a (18b, 18b) _{is smaller than the pitch A 1} of the large diameter wires 16a, 16a (16b, 16b), and the large diameter wires 16a The sizes of the lead angles α _a and α _b of 16b and the sizes of the lead angles β _a and β _b of the small diameter wires 18a and 18b are substantially equal to each other. Therefore, the mesh of the peripheral wall formed only by the small diameter wires 18a and 18b is finer than the mesh of the peripheral wall formed only by the large diameter wires 16a and 16b, that is, the large diameter wires 16a, The pores 22 formed by the small diameter strands 18a and 18b are smaller than the pores 20 formed by 16b. The pores 22 formed by the strands having a small expanding force refer to the pores formed by the small diameter strands 18a (18b) in the presence of the large diameter strands 16a (16b), for example, the small diameter strands. Not only the pores formed only by the 18a and 18b, but also the pores formed by the large diameter wire 16a (16b) and the small diameter wire 18a (18b) are included.

On the other hand, as shown in FIG. 3, the axially both ends 24, 24 of the stent 10 have a flare structure that expands to the outer peripheral side as it becomes outward in the axial direction.

That is, in the vicinity of both ends in the axial direction of the peripheral wall 12, the large-diameter wire 16a wound in one direction in the circumferential direction and the large-diameter wire 16b wound in the other direction in the circumferential direction intersect at an intersection 26. Then, they are overlapped inside and outside the peripheral wall. In the present embodiment, six large-diameter strands 16a wound in one direction in the circumferential direction and six large-diameter strands 16b wound in the other direction in the circumferential direction are provided, so that the intersection 26 However, six are provided at substantially equal intervals on the same circumference in the vicinity of both ends in the axial direction of the peripheral wall 12.

Then, at the six intersections 26, the ends of the large-diameter strands 16a and 16b forming the intersections 26 and 26 adjacent to each other in the circumferential direction are ends made of the same wire as the large-diameter strands 16. They are connected to each other by a member 28. In short, in the present embodiment, six end members 28 are provided at both ends 24 and 24 in the axial direction of the stent 10, and are connected to the large-diameter wire 16.

These end members 28 have a folded-back portion 30 at an intermediate portion in the length direction located at the outer end portion in the axial direction. As a result, both ends 24, 24 in the axial direction of the stent 10 have an end structure in which the ends of the large-diameter strands 16a, 16b are connected to each other and folded back in a loop shape, and the end member 28 Since the folded-back portion 30 is located on the outer peripheral side of the peripheral wall 12, it has a flare structure that expands to the outer peripheral side as it goes outward in the axial direction.

The large-diameter strands 16a and 16b and the end member 28 are connected by a cylindrical connecting member 32. That is, by fitting the large-diameter strands 16a and 16b and the ends of the end member 28 into the openings at both ends of the cylindrical connecting member 32, the large-diameter strands 16a and 16b and the end member 28 are mutually attached. It is designed to be connected. The large-diameter strands 16a and 16b and the end member 28 may be connected by adhesion or welding instead of the connecting member 32, or may be connected by the connecting member 32. Later, if necessary, adhesion or welding may be applied.

The flared and loop-shaped end structures are formed with respect to the ends of the large-diameter strands 16a and 16b after the large-diameter strands 16a and 16b and the small-diameter strands 18a and 18b are woven to form the peripheral wall 12. It can be formed by connecting the end member 28 with the connecting member 32. The ends of the small diameter wires 18a and 18b do not need to be separately treated after the peripheral wall 12 is formed, and the ends of the small diameter wires 18a and 18b are fixed to each other by welding or adhesion. You may perform edge processing such as.

Here, the large-diameter strands 16a, 16b, the small-diameter strands 18a, 18b, and the end member 28 constituting the stent 10 can be formed of a Ni—Ti alloy or the like having a shape memory capability.

The stent 10 as described above is, for example, mechanically reduced in diameter and housed in a sheath provided in the stent delivery catheter in such a reduced diameter state. Then, after being delivered to the narrowed portion in the lumen of the body by such a stent delivery catheter, the stent 10 is exposed from the sheath and exposed to body temperature, so that the stent 10 exhibits superelasticity (pseudoelasticity) and automatically expands in diameter. It is designed to do. As a result, the narrowed portion in the lumen of the body can be expanded to restore blood flow and the like.

In the stent 10 of the present embodiment, the size of the pores 22 formed by the small diameter strands 18a and 18b is sufficiently reduced, so that the tissue constituting the narrowed portion protrudes into the stent 10 through the pores and the internal tube. It can prevent the lumen from restenosis. In particular, by adopting a wire 14 having a small diameter as the wire 14 constituting the peripheral wall 12 of the stent 10, the number of wire 14 can be increased and the size of the pore 22 can be efficiently reduced.

Further, although there is a possibility that the expansion force at the time of expansion may decrease by adopting a small diameter wire 14 as the wire 14, the large diameter wire 16a and 16b are also used as the wire 14 and the large diameter wire 16a is used. , 16b and the small diameter strands 18a and 18b are woven together to form the peripheral wall 12. Therefore, the expanding force is supplemented by the large-diameter strands 16a and 16b, and the stent 10 can be stably expanded.

In particular, since the peripheral wall 12 has a single-layer structure, unlike a stent having a conventional structure, the possibility of delamination is avoided, and for example, a lumen such as a blood vessel due to thrombus or the like adhering to the inner layer is avoided. Restenosis can also be effectively prevented.

Further, in the present embodiment, since the number of large diameter wires 16a and 16b is smaller than the number of small diameter wires 18a and 18b, a sufficient number of small diameter wires 18a and 18b is secured. , The size of the pores 22 can be stably reduced. Further, it is possible to avoid the possibility that the number of large-diameter strands is too large and the stent becomes hard, which hinders deformation such as expansion and contraction and bending.

Furthermore, since a plurality of large-diameter strands 16a and 16b and small-diameter strands 18a and 18b are provided in a spiral shape in opposite directions, the peripheral wall 12 is formed into a mesh shape, and the pores 20 and 22 are formed. The strength of the stent 10 can be stably obtained while the size is sufficiently reduced. That is, compared to the structure in which the large-diameter wire is spirally wound in only one direction, the large-diameter wire is spirally wound in both directions to form a grid-like pore only with the large-diameter wire. Therefore, it is possible to stabilize the shape at the time of expansion / contraction deformation and to secure the diameter expansion force more effectively. Further, compared to the structure in which the small-diameter wire is spirally wound in only one direction, the small-diameter wire is spirally wound in both directions to form a grid-like pore only with the small-diameter wire. Therefore, it becomes possible to realize pores having a smaller mesh diameter.

In particular, since the large-diameter strands 16a and 16b and the small-diameter strands 18a and 18b are woven at equal intervals as a whole and at substantially the same lead angle, when the diameter of the stent 10 is reduced, for example, from the stent 10. The risk of the strand 14 being caught in the stent delivery catheter, sheath, or the like due to partial protrusion can be further effectively reduced.

Further, in the present embodiment, since the axial end portions 24, 24 of the stent 10 have a flared structure, the axial end portions 24, 24 are stable on the lumen wall surface when placed in the lumen of the body. Pressed, the stent 10 is stably placed in the desired position within the lumen. In particular, since the axial end portions 24, 24 also have a loop structure, the possibility that the axial end portions 24, 24 of the stent 10 pierce the lumen wall surface can be reduced.

Next, FIGS. 4 and 5 show a stent 40 as a second embodiment of the present invention. Also in this embodiment, the peripheral wall 42 of the stent 40 is formed by weaving a plurality of types of strands 44 having different expanding forces into each other. Since the same structure as that of the first embodiment can be adopted as the structure of both ends in the axial direction of the stent 40, FIG. 4 shows only the peripheral wall 42 which is the intermediate portion in the axial direction of the stent 40. Further, the members or parts substantially the same as those of the embodiment are designated by the same reference numerals as those of the embodiment in the drawings, and detailed description thereof will be omitted.

That is, the strands 44 forming the peripheral wall 42 are the large-diameter strands 46a wound in one direction in the circumferential direction as the strands having a large expansion force and the large-diameter strands 46b wound in the other direction in the circumferential direction. It is composed of a small-diameter wire 48a wound in one direction in the circumferential direction and a small-diameter wire 48b wound in the other direction in the circumferential direction as a wire having a small expansion force. In the present embodiment, six large-diameter wire wires 46a wound in one direction in the circumferential direction and six large-diameter wire wires 46b wound in the other direction in the circumferential direction are provided, while one in the circumferential direction. Twenty-four small-diameter wire wires 48a wound in the direction and 24 small-diameter wire wires 48b wound in the other direction in the circumferential direction are provided.

_{In the present embodiment, the lead angles γ a} (see FIG. 5) of the large-diameter wire 46a wound in one direction in the circumferential direction are substantially equal to each other, and are wound in the other direction in the circumferential direction. _{The lead angles γ b} (see FIG. 5) of the large-diameter strands 46b are also substantially equal to each other. Then, the magnitude of these lead angles γ _{a and} the magnitude of γ _b are substantially equal (| γ _a | = | γ _b |).

_{Further, the lead angles δ a} (see FIG. 5) of the small diameter wires 48a wound in one direction in the circumferential direction are substantially equal to each other, and the small diameter wires 48b wound in the other direction in the circumferential direction are substantially equal to each other. The lead angles δ _b (see FIG. 5) of the above are substantially equal to each other. Then, the magnitude of these lead angles δ _{a and} the magnitude of δ _b are substantially equal (| δ _a | = | δ _b |).

The lead angles of the large-diameter strands 46a and 46b and the small-diameter strands 48a and 48b are different in size. That is, the lead angles γ _a and γ _b of the large diameter wires 46a and 46b are larger than _{the lead angles δ a} and δ _{b of} the small diameter wires 48a and 48b _{(| δ a} | = | δ _b). ｜ ＜ ｜ γ _a ｜ ＝ ｜ γ _b ｜).

Further, also in the present embodiment, the pitch of the small diameter wires 48a, 48a (48b, 48b) is smaller than the pitch of the large diameter wires 46a, 46a (46b, 46b), and the pitch and the lead angle are reduced. Therefore, as compared with the pores 50 formed by the large-diameter strands 46a and 46b, the pores 52 formed by the small-diameter strands 48a and 48b, or the large-diameter strands 46a (46b) and the small-diameter strands 48a (48b) The pores 52 formed by the above are made smaller. Therefore, the stent 40 of the present embodiment can exhibit the same effect as the stent 10 of the first embodiment.

The stent 40 of the present embodiment is formed by, for example, the manufacturer directly weaving the large-diameter strands 46a and 46b into the stent (peripheral wall) formed only of the small-diameter strands 48a and 48b. obtain. Further, the method for manufacturing a stent (peripheral wall) formed only of the small-diameter strands 48a and 48b is not limited in any way, and may be formed by, for example, an automatic loom or weaving by a procedure.

Next, FIGS. 6 and 7 show a stent 60 as a third embodiment of the present invention. Also in this embodiment, the peripheral wall 62 of the stent 60 is formed of a plurality of types of strands 64 having different expanding forces, and is a large-diameter strand that winds in one direction in the circumferential direction as a strand having a large expanding force. 66a and a large-diameter wire 66b that winds in the other direction in the circumferential direction, a small-diameter wire 68a that winds in one direction in the circumferential direction as a wire with a small expansion force, and a small diameter that winds in the other direction in the circumferential direction. It is composed of the strands 68b and the strands 68b being woven together. In the present embodiment, six large-diameter strands 66a wound in one direction in the circumferential direction and six large-diameter strands 66b wound in the other direction in the circumferential direction are provided, while one in the circumferential direction. Forty-six small-diameter wires 68a wound in the direction and 46 small-diameter wires 68b wound in the other direction in the circumferential direction are provided. Since the structure of both ends in the axial direction of the stent 60 can be the same as that of the first embodiment, FIG. 6 shows only the peripheral wall 62 which is the intermediate portion in the axial direction of the stent 60.

_{In the present embodiment, the pitches (axial spacing) A 2} (see FIG. 6) of the large-diameter strands 66a, 66a (66b, 66b) adjacent in the axial direction are substantially equal to each other, and are adjacent in the axial direction. _{The pitches B 2} (see FIG. 7) of the small diameter strands 68a and 68a (68b, 68b) are substantially equal to each other. _{The pitch B 2} of the small diameter wires 68a, 68a (68b, 68b) is smaller than _{the pitch A 2} of the large diameter wires 66a, 66a (68a, 68a) _{(B 2} <A ₂ ).

Then, the large diameter wires 66a, 66a (66b, 66b) are woven into the small diameter wires 68a, 68a (68b, 68b), and in the present embodiment, the large diameter wires 66a (66b) are woven. It is woven so as to overlap the small diameter wire 68a (68b) existing at the arrangement position from the outer peripheral surface. Therefore, in FIG. 7, the small-diameter wire 68a (68b) that overlaps under the large-diameter wire 66a (66b) does not appear in the drawing.

Even in the stent 60 of the present embodiment having the above-mentioned shape, the pores 72 formed by the small diameter wires 68a and 68b are smaller than the pores 70 formed by the large diameter wires 66a and 66b. Therefore, the same effect as that of the stent 10 of the first embodiment can be exhibited.

Similarly to the stent 40 of the second embodiment, the stent 60 of the present embodiment also has the large diameter strands 66a and 66b with respect to the stent (peripheral wall) formed of, for example, the small diameter strands 68a and 68b. , Can be formed by the manufacturer directly weaving by hand.

Next, FIGS. 8 and 9 show a stent 80 as a fourth embodiment of the present invention. Also in this embodiment, the peripheral wall 82 of the stent 80 is formed of a plurality of types of strands 84 having different expanding forces, and is a large-diameter strand that is wound in one direction in the circumferential direction as a strand having a large expanding force. 86a and a large-diameter wire 86b that winds in the other direction in the circumferential direction, a small-diameter wire 88a that winds in one direction in the circumferential direction as a wire with a small expansion force, and a small diameter that winds in the other direction in the circumferential direction. It is composed of the strands 88b and the strands 88b being woven together. Since the same structure as that of the first embodiment can be adopted as the structure of both ends in the axial direction of the stent 80, FIG. 8 shows only the peripheral wall 82 which is the intermediate portion in the axial direction of the stent 80.

In the present embodiment, 12 large-diameter strands 86a wound in one direction in the circumferential direction and 12 large-diameter strands 86b wound in the other direction in the circumferential direction are provided, while one in the circumferential direction. Twelve small-diameter wires 88a wound in the direction and twelve small-diameter wires 88b wound in the other direction in the circumferential direction are also provided.

In the stent 80 of the present embodiment, the entire strand 84 composed of the large diameter strands 86a and 86b and the small diameter strands 88a and 88b is woven at substantially equal intervals and at substantially the same lead angle. Therefore, the large-diameter strands 86a and 86b and the small-diameter strands 88a and 88b are mechanically and simultaneously woven by, for example, an automatic loom.

Further, the stent 80 of the present embodiment is provided with 12 large-diameter strands 86a wound in one direction in the circumferential direction and 12 large-diameter strands 86b wound in the other direction in the circumferential direction. Therefore, twelve intersections (26) of the two large-diameter strands 86a and 86b provided at both ends (24, 24) in the axial direction of the stent 80 are formed at equal intervals on the circumference. Then, at the 12 intersections (26), the ends of the large-diameter strands 86a and 86b forming the intersections (26,26) adjacent to each other in the circumferential direction are mutually connected by the end member (28). Is connected to. In short, in the present embodiment, 12 end members (28) similar to those in the first embodiment are provided at both ends (24, 24) in the axial direction of the stent 80.

Also in the stent 80 of the present embodiment having such a shape, the large-diameter wire 86a (86b) and the small-diameter wire 88a (88b) are formed as compared with the pores 90 formed by the large-diameter wires 86a and 86b. The pores 92 are smaller. Therefore, even when the number of large-diameter strands 86a and 86b and the number of small-diameter strands 88a and 88b are the same as in the present embodiment, the same effect as that of the first embodiment can be obtained. Can be demonstrated.

Although the embodiments of the present invention have been described above, the present invention is not limitedly interpreted by the specific description in the embodiments, and various changes, modifications, improvements, etc. are made based on the knowledge of those skilled in the art. It can be carried out in the form of adding.

For example, the shape of the axial end of the stent is not limited to that of the first embodiment. That is, in the first embodiment, the ends of the large-diameter strands 16a and 16b forming the intersections 26 and 26 adjacent to each other in the circumferential direction among the six intersections 26 are end members 28, respectively. However, for example, the shape shown in FIG. 10 can also be adopted. In the stent 100 shown in FIG. 10, at both ends 102 and 102 in the axial direction, the ends of the large-diameter strands 16a and 16b are connected so as to connect the intersections 26 and 26 adjacent in the circumferential direction among the six intersections 26 on the circumference. They are connected to each other by an end member 28 via a connecting member 32. The central portion of the peripheral wall 12 of the stent 100 in the axial direction has the same structure as that of the first embodiment, and thus is not shown. Further, at the three intersections (26) on the back side of the paper surface in FIG. 10, the ends of the large-diameter strands 16a and 16b are connected in the same manner as the three intersections 26, 26, 26 on the front side of the paper surface.

Alternatively, it may have an end shape such as the stent 110 shown in FIG. At one end 112 in the axial direction (left side in FIG. 11) of the stent 110 shown in FIG. 11, the intersection 26 is configured so as to connect two of the three intersections 26 on the front side of the paper in FIG. The ends of the large-diameter strands 16a and 16b are connected to each other by the end member 28 via the connecting member 32, respectively. The other end 112 in the axial direction of the stent 110 has the same structure as that of the first embodiment. Further, at the three intersections (26) on the back side of the paper surface in FIG. 11, the ends of the large-diameter strands 16a and 16b are connected in the same manner as the three intersections 26, 26, 26 on the front side of the paper surface.

However, the shape of the end of the stent shown in the above-described embodiment and FIGS. 10 and 11 is merely an example, and the shape of the end of the stent is not limited in any way. As with the small-diameter wire, the portion does not have to be end-treated.

In the above-described embodiment and the embodiments shown in FIGS. 10 and 11, a plurality of large-diameter strands 16a and 16b have been adopted, but it is also possible to use one large-diameter strand. That is, one large-diameter wire is wound in the circumferential direction while being woven into a stent (peripheral wall) formed in advance by the small-diameter wire, and at the end in the axial direction, it is folded back in a loop and further wound in the circumferential direction. It is also possible to rotate and repeat this to form a mesh-like peripheral wall with one large-diameter wire and a small-diameter wire. The ends of the large-diameter strands in the length direction may be free ends at the axially intermediate portion of the stent, but it is preferable that they are bonded or welded to each other. By weaving the large-diameter wire as one wire in this way, it is possible to avoid the trouble of post-fixing the end member or the like after forming the peripheral wall.

Further, in the second and third embodiments, after forming a stent (peripheral wall) composed of small-diameter strands 18a and 18b in advance, large-diameter strands 16a and 16b are woven into the stent (peripheral wall) by a procedure. For example, a stent (peripheral wall) made of a large-diameter wire may be formed in advance, and then a small-diameter wire may be woven into the stent (peripheral wall) by a procedure. The method for manufacturing these preformed stents (peripheral walls) is not limited in any way. That is, in addition to weaving the strands by an automatic loom or a procedure, they may be formed by laser cutting, electroforming, etching, or the like. In this way, when a large-diameter wire or a small-diameter wire is woven by a procedure, the base stent (peripheral wall) may be, for example, a conventionally known stent made of a wire-shaped peripheral wall.

Further, in the above-described embodiment, the large-diameter strands 16a, 46a, 66a, 86a and the large-diameter strands 16b, 46b, 66b, 86b have spiral shapes in opposite directions to each other. It may have a spiral shape that winds in only one direction. Similarly, the small-diameter wire may also have a spiral shape that winds in only one direction in the circumferential direction. In such a case, the gaps corresponding to the pitches of the large-diameter strands and the small-diameter strands are pores formed by the strands having a large or small expanding force. However, the large-diameter wire, the small-diameter wire, or both do not have to extend spirally.

Further, in the above embodiment, the large diameter wires 16a, 16b, 46a, 46b, 66a, 66b, 86a, 86b and the small diameter wires 18a, 18b, 48a, 48b, 68a, 68b, 88a, 88b are woven by plain weave, respectively. The peripheral walls 12, 42, 62, and 82 were formed by being formed, but the peripheral wall may be formed by braiding the large-diameter wire and the small-diameter wire, respectively. The braiding method for the large-diameter wire and the small-diameter wire is not limited in any way, and any conventionally known braiding method such as knitting, rubber knitting, and pearl knitting can be adopted.

Further, in the above-described embodiment, as a plurality of strands having different expansion forces, large-diameter strands 16a, 16b, 46a, 46b, 66a, 66b, 86a, 86b and small-diameter strands 18a having different thicknesses are used. , 18b, 48a, 48b, 68a, 68b, 88a, 88b have been adopted, but the expanding force may be different by changing the material of the wire, for example. That is, for example, a Ni—Ti alloy having a certain level of strength is used as a material for a wire having a large expanding force, and a shape memory polymer such as polynorbornene or transpolyisoprene, which is flexible to some extent as a material for a wire having a small expanding force, etc. May be adopted.

In the present invention, the entire stent does not have to have a composite structure of a wire having a large expanding force and a wire having a small expanding force. For example, a part of the stent in the axial direction or the circumferential direction expands. It suffices to have a composite structure of a wire having a large force and a wire having a small expansion force.

Further, in the above-described embodiment, the large-diameter wires 16a, 16b, 46a, 46b, 66a, 66b, 86a, 86b and the small-diameter wires 18a, 18b, 48a, 48b, 68a, 68b, 88a, 88b are in the axial direction. Over approximately the entire length, the pitch and lead angle, that is, the sizes of the pores 20, 22, 50, 52, 70, 72, 90, 92 formed by these were approximately equal, but these were axially equal. It may be different. Therefore, in the present invention, it is not necessary to make the pores formed by the wire having a small expanding force smaller than the pores formed by the wire having a large expanding force over the entire length in the axial direction, and the expanding force does not need to be reduced. It is sufficient that there is at least one pore formed by the wire having a small expanding force, which is smaller than the pore formed by the wire having a large size.

Further, in the above-described embodiment, as the strands having different expansion forces, the large-diameter strands 16a, 16b, 46a, 46b, 66a, 66b, 86a, 86b and the small-diameter strands 18a, 18b, 48a, 48b, 68a, 68b, Two types of 88a and 88b have been adopted, but for example, three or more types of strands having different expansion forces may be adopted by changing the thickness and material. In such a case, it is not necessary for the size of the pores formed by the strands to increase in order as the expanding force increases, and the pores formed by the strands having the smallest expanding force need not be increased in order. When the pores formed by the wire having the expanding force of the above are larger, the pore formed by the wire having the largest expanding force has the above-mentioned wire having the smallest expanding force or a medium expanding force. It may be made smaller than the pores formed by the strands.

The invention described in the present specification and the like originally includes the aspects described below, and the configuration, action and effect thereof, etc. will be added.

In the aspect (i), a single-layer peripheral wall having a composite structure in which a plurality of types of strands are woven or braided with each other is formed, and the pores formed by the strands having a large expanding force in the peripheral wall are formed. It is a stent characterized in that the pores formed by the strands, which have a smaller expanding force, are made smaller.

According to the stent having a structure according to this embodiment, the small pores formed by the strands having a small expanding force effectively prevent the tissue forming the stenosis from protruding into the stent. Further, since the wire having a large expansion force is woven or braided with respect to the wire having a small expansion force, the wire having a large expansion force can sufficiently secure the expansion force of the stent.

In particular, since the peripheral wall of a single layer is formed by these strands having a large expanding force and the strands having a small expanding force, when the stent is placed in a curved portion of the lumen like the stent described in Patent Document 1. There is no separation between the inner layer and the outer layer. Further, since the wire having a large expansion force and the wire having a small expansion force are fixed by weaving or braiding each other, it is not necessary to separately provide a member or the like for connecting the two wires to each other.

In the aspect (ii), in the stent according to the aspect (i), at least one of the material and the thickness of the wire having a large expanding force and the wire having a small expanding force are different.

According to the stent having a structure according to this aspect, for example, a wire having a large expansion force has a larger diameter than a wire having a small expansion force, or a hard material is used as the material of the wire. By doing so, it can be easily formed.

In the aspect (iii), in the stent according to the aspect (i) or (ii), the number of the strands having a large expanding force is smaller than that of the strands having a small expanding force. Is.

According to the stent having a structure according to this aspect, the number of strands having a large expanding force can be reduced as compared with the strands having a small expanding force, so that, for example, the distance between the strands having a large expanding force can be increased. As a result, the pores formed by the wire having a large expanding force can be made larger than the pores formed by the wire having a small expanding force. In addition, if the number of wires with a large expansion force is too large, the stent may become too stiff. Therefore, by reducing the number of wires with a large expansion force compared to the wires with a small expansion force, the stent may become too stiff. Moderate flexibility can be obtained.

In the aspect (iv), in the stent according to any one of the embodiments (i) to (iii), a plurality of the strands are arranged in a spiral shape in opposite directions, and spirals in opposite directions. The shaped strands are woven so as to be woven inside and outside the layer constituting the peripheral wall to form a single layer.

According to the stent having a structure according to this embodiment, for example, a wire having a large expansion force and a wire having a small expansion force are woven in a spiral shape in opposite directions, so that the peripheral wall of the stent has a mesh shape. Therefore, the size of the pores can be made smaller.

In the aspect (v), in the stent according to any one of the embodiments (i) to (iv), a plurality of strands having a small expanding force are arranged in a spiral shape in opposite directions to each other. The wires having a small expansion force, which are spiral in the opposite direction, are woven so as to be woven inside and outside the layer constituting the peripheral wall, while the wires having a large expansion force are woven in at least one direction. At least one wire is arranged in a spiral shape, and the wire having a large expansion force is woven so as to be woven inside and outside the layer constituting the peripheral wall with respect to the wire having a small expansion force to form a single layer. It constitutes.

According to the stent having a structure according to this embodiment, since the strands having a small expanding force spiraling in opposite directions are also woven together, the pores are small due to these plurality of strands having a small expanding force. A mesh-like peripheral wall can be stably formed.

In the stent according to the aspect (iv) or (v), the lead angle of the wire having a large expansion force is the lead angle of the wire having a small expansion force. Is larger than.

According to the stent having a structure according to this embodiment, the lead angle of the wire having a large expansion force is different from the lead angle of the wire having a small expansion force. After forming the peripheral wall, it is also possible to weave a wire having a large expanding force on the peripheral wall formed by the wire having a small expanding force in a spiral shape in the opposite direction by the technique of the manufacturer. In particular, by making the lead angle of the wire with a large expansion force larger than the lead angle of the wire with a small expansion force, it is formed by the wire having a larger expansion force than the pores formed by the wire with a smaller expansion force. The size of the pores can be increased more easily.

In the aspect (vii), in the stent according to the aspect (iv) or (v), the strands including the strands having a large expanding force and the strands having a small expanding force are at equal intervals as a whole. It is woven with the same lead angle.

According to the stent having a structure according to this aspect, the strands having a large expanding force and the strands having a small expanding force are woven as a whole at equal intervals and at the same lead angle, so that, for example, the expanding force is large. It is also possible to weave a wire and a wire with a small expansion force by a machine at the same time. In particular, since the wire having a large expansion force and the wire having a small expansion force are woven at the same lead angle, the stent can be contracted substantially evenly over the entire circumference when the diameter of the stent is reduced. Therefore, when the stent is inserted into the sheath or the like, the possibility that a part of the stent protrudes to the outer peripheral side and is caught by the sheath or the like can be reduced.

Aspect (viii) is a stent according to any one of the embodiments (i) to (vii), wherein a plurality of the strands having a large expanding force are formed at at least one end in the longitudinal direction of the peripheral wall. It has an end structure in which the ends are connected to each other and folded back in a loop shape.

According to the stent having a structure according to this embodiment, since the end has a loop structure, the risk of the end sticking to the wall surface of the lumen when the stent is placed in the lumen is reduced. Can be done.

10, 40, 60, 80, 100, 110: Stent, 12, 42, 62, 82: Peripheral wall, 14, 44, 64, 84: Wire, 16, 16a, 16b, 46a, 46b, 66a, 66b, 86a , 86b: Large diameter wire (wire with large expansion force), 18,18a, 18b, 48a, 48b, 68a, 68b, 88a, 88b: Small diameter wire (wire with small expansion force), 20, 50, 70, 90: Pore (pore formed by a wire having a large expanding force), 22, 52, 72, 92: Pore (pore formed by a wire having a small expanding force)

Claims (1)

A single-layer peripheral wall composed of a composite structure in which a wire having a small expansion force and a wire having a large expansion force having different expansion forces are woven or braided with each other is formed, and the peripheral wall has a large expansion force. While the pores formed by the strands, which have a smaller expanding force than the pores formed by the strands, are smaller.
A plurality of the strands having a small expanding force are arranged in a spiral shape in opposite directions, and the strands having a small expanding force spiraling in opposite directions are inside and outside the layer constituting the peripheral wall. It is woven so that it overlaps with
A layer in which at least one wire having a large expansion force is arranged in a spiral shape in at least one direction, and the wire having a large expansion force constitutes the peripheral wall with respect to the wire having a small expansion force. By forming a single layer by being woven so as to be woven inside and outside the structure, the peripheral wall of the single layer made of the composite structure is formed, and at the same time, the peripheral wall of the single layer is formed.
A stent characterized in that the lead angle formed only by the wire having a large expanding force among the strands is larger than the lead angle formed only by the strand having a small expanding force.

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