JP2002345971A - Stent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stent having a large number of partially folding parts, which can be extended and deformed in a diagonal pattern surrounded with struts as linear elements. SOLUTION: The stent has a plurality of polygonal patterns surrounded with struts as linear elements parallel located in peripheral and axial directions. At least three partially folding parts can be extended, deformed, and are located on polygonal pattern so that the surrounding length of the polygonal pattern can be widened into 1.3 to 2.0 times as long as the original linear surrounding length by pressing and widening that polygonal pattern form inside to outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates generally to a stent for implantation in a living body.

[0002]

2. Description of the Related Art A stent is used to treat a variety of diseases caused by stenosis or occlusion of a blood vessel or other body lumen, thereby expanding the stenosis or occlusion and maintaining the lumen size. Medical devices to be placed there for use, consisting of a single linear metal or coiled stent made of a polymer material, a metal tube cut out by a laser, and a linear member processed by a laser And those made by weaving a plurality of linear metals. These are disclosed in JP-A-8-332230.

[0003] A product obtained by fixing (premounting) this stent in a contracted state to a balloon catheter (stent delivery catheter) is obtained. In actual use, the stent delivery catheter is guided to the vascular stenosis in a state where the stent is pre-mounted, and the balloon is expanded to expand and place the stent in the vascular stenosis. Thereafter, the stent delivery catheter is pulled out of the body. Regarding this pre-mounting,
00-189520 and the like.

[0004] A linear element which is a minimum unit constituting a stent processed by a laser is called a strut. Stent designs are broadly classified into two types, open and closed, depending on the pattern formed by the struts.

[0005] The open type is disclosed in Japanese Patent No. 2645203.
As disclosed in Japanese Patent Application Laid-Open No. H11-260, one segment in which a wave (sine wave) shape is repeated in the circumferential direction is repeated in a plurality of segments in the axial direction, and the portion between them is connected by one to three connection segments per circumference. Things.

On the other hand, the closed type is Japanese Patent Publication No. 4-637.
No. 7, JP-A-10-137345, JP-T10-503
As disclosed in US Pat. No. 676 or the like, a polygon is formed (closed) by struts, the sides of the polygon are shared, and the polygon is repeated in the circumferential direction and the axial direction. Some of these polygons improve the flexibility of the stent by providing locally small curves or wavy portions called flexible links as shown in the above-mentioned patents.

The advantages and disadvantages of each are as follows.

The first advantage of the open type is that it is rich in flexibility in the axial direction and excellent in insertion into a bent blood vessel. Another major advantage is that the Y-stent technique for branch vessels can be performed. Y stent or Y
The procedure called stenting is a procedure in which one stent is placed in each of the main vessel and the side branch vessel when there is stenosis in the bifurcation vessel. Recently, the procedure examples have been increasing.
This is one of the important performance requirements for a stent. Regarding this technique, "PT
22 of "CA Technique Kazuaki Mitou". The bifurcation stent (page 203) has details. That is, FIG.
As shown in FIG. 1, the first stent 101 is placed from the proximal portion 103 of the main blood vessel 1 to the distal portion 104 of the main blood vessel 1,
Further, the second stent 102 is inserted into the proximal portion 1 of the main blood vessel 1.
The stent is indwelled from 03 to the side branch 2, so that two stents overlap at the proximal portion 103 of the main blood vessel 1. In this procedure, first place the first stent in the main vessel,
Thereafter, the stent delivery catheter having the second stent premounted thereon is delivered toward the side branch by passing through the opening (gap) between the first stent struts, and one main vessel proximal portion is provided. With the balloon positioned over the opening (void) between the stent struts of the eye and the side branch entrance, the balloon is inflated. As a result, the stent is placed between the proximal portion of the main blood vessel and the opening (gap) between the first stent struts and the side branch entrance.

In the case of the open type, there are only one to three connecting segments per circumference, and the perimeter of the gap formed between the struts is long. Therefore, the stent delivery catheter is provided in the gap between the struts. When the balloon is expanded through the strut, the struts are deformed, and the voids formed between the struts are simultaneously deformed, so that the opening area becomes large, and thus the side branch can be accessed.

However, as a disadvantage, there is a problem that the resistance (radial force) to the force of the blood vessel to contract is very small, and the blood vessel is easily contracted by the pressure to contract. In addition, since the length of the periphery of the gap formed between the above-described struts is large, when the stent is expanded and placed in a bent blood vessel, the gap positioned outside the bend is greatly opened, and the blood vessel is opened. Endothelial tissue may protrude significantly into the stent, causing restenosis. The performance indicating how small the opening area of the void portion is is called scaffolding.

On the other hand, the advantage of the closed type is that the strut forms a polygon, and the polygon is repeated in the circumferential direction and the axial direction while sharing sides, so that the above-mentioned radial force is very large. is there. At the same time, because there is a polygon whose perimeter is limited, even if it is placed in a bent blood vessel, the polygon that is the void positioned outside the bend does not open beyond the area of the shape, The above-mentioned scaffolding property is good.

However, there is a disadvantage that the above-mentioned Y stent cannot be applied to the branch vessel. In other words, when performing a Y stent, through a polygon that is a gap between the struts of the closed type, in the direction of the side branch blood vessel, passing through a balloon of another stent delivery catheter and expanding it, the perimeter of this polygon is limited. Because of this, the polygon is not opened much larger and therefore no access to the side branches is possible. In order to solve this, it is conceivable to increase the area of the polygon. However, when such a thing is performed, as in the case of the open type, the scaffolding property is sacrificed.

[0013]

SUMMARY OF THE INVENTION In view of these circumstances, what the present invention seeks to solve is to maintain the advantages of the closed type, conversely solve the disadvantages, and at the same time, without causing the disadvantages of the open type. The purpose is to provide a closed type stent having only advantages.

More specifically, it is an object of the present invention to enable a Y-stent to a branch vessel, which is a disadvantage of the closed type, while maintaining high radial force, which is an advantage of the closed type, and excellent scaffolding.

[0015]

SUMMARY OF THE INVENTION The present invention is a closed-type stent which maintains excellent scaffolding performance and high radial force in a substantially polygonal pattern surrounded by struts which are linear elements. In order to have the linear perimeter and the opening area of the degree required for the polygonal pattern, at the same time, the polygonal pattern is expanded from the inside to the outside of the polygonal pattern, So that the opening of the pattern is widened (expandable and deformable) enough to access the side branch
It is to arrange a relatively large number of locally folded portions that can be extended and deformed.

That is, a substantially polygonal pattern which is formed in a substantially tubular body and can be extended radially outward of the substantially tubular body, and which is surrounded by struts which are linear elements, has a circumferential direction. And a plurality of axially aligned stents, wherein the polygonal pattern has a linear perimeter (original linear perimeter) and the polygonal pattern is By expanding from the inside to the outside, the perimeter after the expansion is expanded to 1.3 to 2.0 times the original linear perimeter so that the locally foldable portion that can be stretched and deformed is expanded. The present invention provides a stent characterized by having three or more per polygonal pattern. In addition, it is preferable that the number of locally foldable portions that can be extended and deformed per one polygonal shape pattern is equal to the number of sides of the polygonal shape.

Further, the present invention provides a substantially tubular pattern which is formed in a substantially tubular body, is extendable radially outward of the substantially tubular body, and is surrounded by struts which are linear elements. A plurality of side-by-side, circumferentially and axially aligned stents, wherein the polygonal pattern has a linear perimeter, and the polygonal pattern is pushed from the inside out. By expanding, the polygonal pattern has a stretchable and deformable portion so that the perimeter of the polygonal pattern spreads 1.3 to 2.0 times the linear perimeter, The sum of the linear lengths of the stretchable portions in the direction of the sides of the polygon is formed to be 1/3 to 1 times the linear length of the polygonal pattern. Is to supply a stent that does.

The stent has a high radial force by having a plurality of polygonal patterns in the circumferential and axial directions, and at the same time has excellent scaffolding properties. In addition, since each polygonal shape pattern has a relatively large number of locally foldable portions that can be stretched and deformed as described above, the balloon of another stent delivery catheter disposed on the side branch through this polygonal shape pattern is also provided. The expansion allows the perimeter of the square pattern to be significantly deformed, thus allowing access to the branch vessels and a Y-stent.

Japanese Unexamined Patent Application Publication No. 10-137345,
In the technique described in 503676, etc., two U-shaped portions are opposed to each other in a rhombus formed by struts, and this is intended to give flexibility to the stent in the axial direction. The shape-like portion is not stretched and deformed in order to enable Y-stenting, and there is no such description. Also, in fact, at only two U-shaped portions described in the patent specification per diamond, it is possible to obtain a sufficient opening area for performing side branch access by expanding and expanding the balloon of the stent delivery catheter described above. Can not.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the stent according to the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

FIG. 2 shows an embodiment of the stent 3 according to the present invention (Embodiment 1), and is an expanded view thereof. Stent 3
The strut 4 is formed in a substantially tubular body, is extendable radially outward of the substantially tubular body, and is a linear element.
A plurality of substantially polygonal patterns 5 surrounded by are arranged in the circumferential direction and the axial direction.
"Almost in the shape of a polygon" means that this polygonal shape includes a triangle, a rhombus, a rectangle, a parallelogram, a pentagon, or any polygonal shape, and the corners are not acute but curved. It is meant to include rounded items.

The polygonal pattern 5 has an original linear perimeter. The original linear perimeter is the length indicated by the bold line 6 in FIG. 3 and does not take into account the total length of the torsionally deformable local folding portion 7 which will be described later. Represents the linear minimum perimeter of the polygonal pattern.

The stent 3 of the first embodiment is further expanded in the polygonal pattern portion 5 from the inside to the outside by balloon expansion or the like of the stent delivery catheter, so that the perimeter after the expansion is expanded. Extendable to 1.3 to 2.0 times the original linear circumference.
Are provided for each polygonal pattern.

The stretchable local folding part 7
Is a sine wave shape for two periods in the present embodiment, but as described above, the polygonal pattern portion 5
In the above, by expanding the stent delivery catheter from the inside to the outside by balloon expansion or the like of the stent delivery catheter, the perimeter after the expansion is 1.3 to 2.0 times the original linear perimeter 6. Anything that doubles can be used. On the other hand, the perimeter after being spread here refers to the perimeter of a pattern formed by expanding one original linear perimeter as shown in FIG.

The reason why the perimeter after being expanded by expanding the stent delivery catheter by balloon expansion or the like is 1.3 to 2.0 times the original linear perimeter 6 is as follows. In order to obtain a high radial force and satisfy the excellent scaffolding property, the original linear perimeter 6 of the polygonal pattern portion 5 is selected in a range as described later, and one polygonal shape is selected. The number of locally foldable locally foldable portions 7 per pattern portion 5 is 3
In the case where the number of pieces is larger than the number of pieces, if the circumference of the stent delivery catheter after being expanded by balloon expansion or the like spreads in a range of 1.3 to 2.0 times the original linear circumference, the side branch is accessed. This is because a sufficient opening area / perimeter is obtained.

It is preferable that the number of the locally foldable local folding portions 7 per one polygon-shaped pattern portion 5 is three or more. More preferably, the number is equal to the number of sides of the polygon. . This is because it is better to make the structure of each side of the polygon as similar as possible in order to make the expansion operation, the radial force, and the flexibility, all of them, uniform over the entire stent 3. In the first embodiment, since the parallelogram has four sides, the number of the locally folded portions that can be extended and deformed is four.

The original linear perimeter 6 of the polygonal pattern is preferably 6.0 mm to 12.0 mm in order to obtain a high radial force and satisfy excellent scaffolding properties. Desirably, and more desirably, 8.0 mm to 10.0 mm.

Further, for the same reason, the area of the original opening of the polygonal pattern is 2.
It is desirably 0 mm ² to 9.0 mm ^2, the more desirable is a 3.0 mm ² to 6.25 mm ^2.

FIG. 5 shows another embodiment in which the configuration of the foldable portion that can be extended and deformed is different from that of the first embodiment (Embodiment 2). 1 and shows the polygonal pattern.

That is, the stent 3 is formed in a substantially tubular body, is extendable radially outward of the substantially tubular body, and has a substantially polygonal shape surrounded by struts 4 which are linear elements. The pattern 5 is a plurality of stents arranged in the circumferential direction as well as in the axial direction. Also, "having a substantially polygonal shape" means that the polygonal shape includes a triangle, a rhombus, a rectangle, a parallelogram, a pentagon, or any polygonal shape, and the corners are not acute but curved. It is meant to include rounded items.

The polygonal pattern 5 has an original linear perimeter. The original linear perimeter is the length indicated by the bold line 9 shown in FIG. 5, and does not take into account the total length of the foldable portion 10 that can be stretched and deformed, which will be described later. Represents the linear minimum perimeter of the square pattern.

The stent 3 in Example 2 is further expanded from the inner side to the outer side of the polygonal pattern portion 5 by balloon expansion of a stent delivery catheter, etc. A relatively large number of locally deformable local folds 10 are provided so that the length 8 extends 1.3 to 2.0 times the original linear perimeter 9 and the locally deformable local fold 10 is provided. The sum of the linear lengths of the portions in the side direction of the polygon is
It is formed over 1/3 to 1 times the original linear perimeter of the polygonal pattern. The definition of the linear length in the side direction of the polygon of the locally foldable local folding portion 10 is as shown by the thick line 11 in FIG. 6 (meaning the sum of the thick line portions).

The locally foldable local folding part 1
In the second embodiment, the shape of “0” is substantially a continuous waveform. However, as described above, the balloon expansion of the stent delivery catheter is performed in the polygonal pattern portion 5 from the inside to the outside thereof. Anything can be used as long as the perimeter after being spread is 1.3 to 2.0 times the original linear perimeter 9 by being spread. In the second embodiment, the linear length 11 in the side direction of the polygon of the locally foldable local folding portion 10 is approximately 倍 of the original linear peripheral length 9 of the polygonal pattern. Although it is strongly selected, any number may be used as long as it is in the range of 1/3 to 1 time. Further, the stretchable and deformable folding portion 10 may be continuous around the polygon, or a plurality of discontinuous portions may be used.

Here, the linear length 11 of the stretchable and deformable local folding portion 10 in the side direction of the polygon is represented by
1/3 of the original linear perimeter 9 of the polygonal pattern
In order to obtain a high radial force and satisfy the excellent scaffolding property, the original linear perimeter 9 of the polygonal pattern portion 5 is obtained.
Is selected in a range as described below, and is expanded by balloon expansion or the like of the stent delivery catheter, so that the perimeter 8 after being expanded is the original linear perimeter 9.
Assuming that the distance is 1.3 times to 2.0 times, the linearly foldable local folding portion 10 of one polygonal shape pattern portion 5 in the side direction of the polygon can be used. If the length 11 falls within the range of 1/3 to 1 times the original linear perimeter 9 of the polygonal pattern, after expanding,
This is because a sufficient opening area / perimeter for accessing the side branch is obtained.

The portion of the foldable portion 10 which can be extended and deformed in the axial direction different from the side direction of the polygon cannot be large. This is because when the balloon of the stent delivery catheter contracts and pre-mounts the stent, this protruding portion overlaps with another circumferentially deformable local foldable portion of the polygon adjacent to the circumferential direction, and it is not sufficient. This is because it becomes impossible to premount while maintaining a small outer diameter (low profile). In this sense, the range indicated by the above numerical values is important.

The original linear perimeter 9 of the polygonal pattern is preferably 6.0 mm to 12.0 mm in order to obtain a high radial force and satisfy excellent scaffolding properties. Desirably, and more desirably, 8.0 mm to 10.0 mm.

Further, for the same reason, the area of the original opening of the polygonal pattern after the stent expansion is 2.
It is desirably 0 mm ² to 9.0 mm ^2, the more desirable is a 3.0 mm ² to 6.25 mm ^2.

The stent disclosed in the above two embodiments can maintain a high radial force and have excellent scaffolding properties by having a plurality of polygonal patterns 5 in the circumferential direction and the axial direction. Further, in the polygonal pattern portion 5, by expanding the stent delivery catheter from the inside to the outside by balloon expansion or the like of the stent delivery catheter, the perimeter after the expansion is 1% of the original linear perimeter. In the first embodiment, three or more local portions that can be stretched and deformed are provided in each of the polygonal patterns so as to spread by 3 to 2.0 times. The linear length 11 of the local portion in the side direction of the polygon is formed to be 1/3 to 1 times the original linear length 9 of the polygonal pattern, thereby forming the polygonal shape. Expansion of the balloon of another stent delivery catheter placed in the side branch through the pattern can significantly deform the perimeter of the polygonal pattern, thus providing access to the branch vessel and Y-step. Bet is to become possible.

[0039]

According to the present invention, the advantages of the closed type can be maintained, and at the same time, the disadvantages can be solved, and the closed type stent having only the advantages without creating the disadvantage of the open type, that is, a high radial force,
It is possible to provide a closed-type stent that enables a Y-stent to branch vessels while maintaining excellent scaffolding properties.

[Brief description of the drawings]

FIG. 1 shows a Y stent or Y stenting.

FIG. 2 is a development view of a stent showing the first embodiment of the present invention.

FIG. 3 is a diagram of a polygonal pattern showing an original linear perimeter in Example 1.

FIG. 4 is a diagram showing a perimeter after being spread.

FIG. 5 is a view of a polygonal pattern of a stent showing Example 2 of the present invention.

FIG. 6 is a diagram of a polygonal shape pattern showing a linear length in a side direction of the polygon of a local portion that can be stretched and deformed in a second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Main blood vessel 2 Side branch blood vessel 3 Stent 4 Strut 5 Almost polygonal pattern surrounded by strut 6 Original linear perimeter of this polygonal pattern 7 Local folding part which can be extended and deformed 8 Polygonal shape The perimeter after the pattern is expanded 9 The original linear perimeter of the polygonal pattern 10 The local foldable portion 11 that can be extended and deformed Length 101 First stent (placed in main vessel) 102 Second stent (placed in side branch vessel) 103 Proximal part of main vessel 1 104 Distal part of main vessel 1

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shogo Miki 2-8-A9-706 F-term (reference) 4C167 AA07 AA44 AA47 AA55 BB15 BB17 CC09 FF05 GG02 GG21 HH18

Claims (4)

[Claims] 1. A substantially polygonal pattern formed in a substantially tubular body, extensible radially outward of the substantially tubular body, and further surrounded by struts, which are linear elements, is formed in a circumferential direction. And a plurality of axially aligned stents, wherein the polygonal pattern has a linear perimeter (original linear perimeter) and the polygonal pattern is By expanding from the inside to the outside, the stretchable deformable local fold is such that the perimeter after spreading is 1.3 to 2.0 times the original linear perimeter. A stent having three or more portions per polygonal pattern. 2. The stent according to claim 1, wherein the number of locally foldable portions that can be stretched and deformed per one polygonal pattern is the same as the number of sides of the polygon. 3. A substantially polygonal pattern formed in a substantially tubular body, extensible radially outward of the substantially tubular body, and further surrounded by struts, which are linear elements, is formed in a circumferential direction. And a plurality of axially aligned stents, wherein the polygonal pattern has a linear perimeter (original linear perimeter) and the polygonal pattern is It has a portion that can be stretched and deformed so that the perimeter after being expanded is 1.3 to 2.0 times the original linear perimeter by expanding from the inside to the outside. Then, the sum of the linear lengths of the stretchable deformable local folding portions in the side direction of the polygon is 1/1 / the original linear peripheral length of the polygonal shape pattern.
A stent characterized by being formed three to one times. 4. The original linear peripheral length of the polygonal pattern is 6.0 mm to 12.0 mm, and the area of the opening surrounded by the peripheral length after the stent is expanded after expansion is 2 mm. .0Mm ² to claims 1 to 3 wherein the stent, characterized in that it is 9.0 mm ^2.