JP4819245B2 - Stent - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention generally relates to a stent for implantation in a living body.
[0002]
[Prior art]
Stents are used to treat various diseases caused by stenosis or occlusion of blood vessels or other in-vivo lumens, to expand the stenosis or occlusion site and to maintain the size of the lumen. A medical device comprising a coiled stent made of a single linear metal or polymer material, a metal tube cut out and processed by a laser, and a linear member assembled by welding with a laser And those made by weaving multiple linear metals. These are disclosed in JP-A-8-332230.
[0003]
This stent is fixed (pre-mounted) in a contracted state to a balloon catheter (stent delivery catheter) to obtain a product. In actual use, the stent delivery catheter is guided to the vascular stenosis with the stent 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. This premount is disclosed in Japanese Patent Laid-Open No. 2000-189520.
[0004]
A linear element that is a minimum unit constituting a stent processed by a laser is called a strut. The design of a stent is roughly classified into two types, an open type and a closed type, depending on the pattern formed by the strut.
[0005]
As disclosed in Japanese Patent No. 2645203, the open type repeats one segment in which a wave (sine wave) shape is repeated in the circumferential direction, and repeats a plurality of segments in the axial direction. It is to be connected by connecting segments.
[0006]
The closed type, on the other hand, forms a polygon with a strut (closed) as disclosed in Japanese Patent Publication No. 4-6377, Japanese Patent Application Laid-Open No. 10-137345, Japanese Patent Publication No. 10-503676, and the like. The polygon is repeated in the circumferential direction and the axial direction by sharing. Among these polygons, there is one that improves the flexibility of the stent by providing locally small curved portions or wavy portions called flexible links as shown in the above-mentioned published patents.
[0007]
The advantages and disadvantages of each are as follows.
[0008]
The advantage of the open type is that it is rich in axial flexibility and has excellent insertability into a bent blood vessel. Furthermore, it is a great advantage that a Y-stent procedure can be performed on branch vessels. The technique called Y-stent or Y-stenting is a technique in which one stent is placed in both the main and side branch vessels when there is a stenosis in the bifurcated vessel. This is one of the important performance requirements. Regarding this technique, see “PTCA Technique Kazuaki Mitsudo” published by Medical School. Details are given in the bifurcation stent (page 203). That is, 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, and the second stent 102 is placed proximal to the main blood vessel 1. The stent is placed from the portion 103 to the side branch 2, and two stents overlap at the proximal portion 103 of the main blood vessel 1. In this procedure, a stent in which the first stent is first placed in the main blood vessel and then passed through the opening (gap) between the first stent struts, and the second stent is premounted. The delivery catheter is delivered toward the side branch, and the balloon is expanded in a state where the balloon is positioned across the opening (gap) between the proximal portion of the main blood vessel and the first stent strut and the side branch entrance. As a result, the stent is placed across the proximal portion of the main blood vessel—the opening (gap) between the first stent struts—the side branch entrance.
[0009]
In the case of the open type, there are only 1 to 3 connecting segments per circumference, and the perimeter of the gap formed between the struts is long. Therefore, the balloon of the stent delivery catheter is passed through the gap between the struts. This is because when the struts are expanded, the struts are deformed, and the gap portion formed between the struts is deformed at the same time, and the opening area is increased, so that the side branch can be accessed.
[0010]
However, as a disadvantage, there is a problem that the resistance (radial force) to the force that the blood vessel tends to contract is very small, and the blood vessel tends to contract due to the pressure that the blood vessel tends to contract. In addition, since the length of the peripheral portion of the gap portion formed between the struts is large, when the stent is expanded and placed in the bent blood vessel, the gap portion positioned outside the bend opens greatly, and the blood vessel Endothelial tissue can protrude significantly into the stent and cause restenosis. The performance indicating how small the opening area of the void is called scaffold property.
[0011]
On the other hand, the advantage of the closed type is that the struts form a polygon, and the polygon is repeated in the circumferential direction and the axial direction while sharing a side, so that the radial force described above is very large. At the same time, because there is a polygon with a limited perimeter, even if it is placed in a bent blood vessel, the polygon that becomes the void portion positioned outside the bent does not open beyond the area of the shape, The above-mentioned scaffold property is good.
[0012]
However, there is a disadvantage that the above-described Y-stent to the branch vessel cannot be performed. In other words, when performing a Y-stent, even if a balloon of another stent delivery catheter is passed and expanded in the direction of a side branch vessel through a polygon that becomes a closed type inter-strut gap, the circumference of this polygon is limited. Therefore, the polygon is not opened larger than that, and therefore the side branch cannot be accessed. In order to solve this, it is conceivable to increase the area of the polygon. However, if such a thing is performed, the scaffold property is sacrificed as in the open type.
[0013]
[Problems to be solved by the invention]
In view of these circumstances, the present invention intends to solve a closed type stent that maintains the advantages of the closed type, conversely, solves the disadvantages, and at the same time has only the advantages without causing the disadvantages of the open type. It is to supply.
[0014]
More specifically, it is to enable a Y-stent to a branch vessel, which is a closed type disadvantage, while maintaining high radial force, which is an advantage of the closed type, and excellent scaffolding.
[0015]
[Means for Solving the Problems]
The present invention is a closed type stent, and a linear shape as required to maintain excellent scaffold performance and high radial force in a substantially polygonal pattern surrounded by struts which are linear elements. By opening the polygonal shape pattern from the inside to the outside of the polygonal shape pattern, the opening of the polygonal shape pattern can access the side branch. A relatively large number of locally foldable portions that can be expanded and deformed are arranged so that they can be expanded to a sufficient size (expandable).
[0016]
That is, a substantially polygonal pattern formed in a substantially tubular body and stretchable radially outward of the substantially tubular body and surrounded by struts, which are linear elements, has a circumferential direction and an axis. A plurality of stents arranged in the direction, and the stent has a strut series formed by connecting a plurality of struts in the circumferential direction, and the strut series includes one end portion, the other end portion, and a plurality of folded portions. The polygonal shape pattern has a linear perimeter (original linear perimeter), and the polygonal shape pattern is pushed from the inside to the outside. By expanding, the stretchable local folding portion is expanded so that the perimeter after being expanded is 1.3 to 2.0 times the original linear perimeter. per square shape pattern, have a three or more , Strut connecting excluding strut interconnection located at an axial end portion of the stent has one end, the other end portion, and all of the folded portion is connected to one end of the deformable locally folded portion extends respectively Is to supply a stent characterized by things. Moreover, it is preferable that the number of locally foldable portions that can be stretch-deformed per one polygonal shape pattern is the same as the number of sides of the polygon.
[0017]
Furthermore, the present invention provides a substantially polygonal pattern which is formed in a substantially tubular body and can be extended radially outward of the substantially tubular body, and is surrounded by struts which are linear elements. And a plurality of stents arranged in the axial direction. The stent has a strut train formed by connecting a plurality of struts in a circumferential direction. The strut train includes a first end, a second end, and a plurality of struts. And the polygonal shape pattern has a linear perimeter, and the polygonal shape pattern is expanded from the inside to the outside, thereby the polygonal shape pattern. The polygonal shape pattern has a stretchable portion so that the perimeter of the shape pattern extends 1.3 to 2.0 times the linear perimeter. The linear length of the side of the polygon There are formed over 1/3 to 1 times the linear length of the polygonal shape pattern, a strut connecting excluding strut interconnection located at an axial end portion of the stent has one end, the other end And supplying a stent characterized in that all of the folded portions are connected to one end of a locally folded portion that is stretchable and deformable .
[0018]
By having a plurality of polygonal patterns in the circumferential direction and the axial direction, the stent can maintain a high radial force and at the same time has excellent scaffolding properties. In addition, since each of the polygonal shape patterns 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 that is arranged on the side branch through the polygonal shape pattern. By expansion, the perimeter of the square-shaped pattern can be greatly deformed, thus allowing access to branch vessels and Y-stents.
[0019]
In the techniques described in JP-A-10-137345, JP-T-10-503676, etc., there are two U-shaped portions facing each other in the rhombus formed by the struts. This is flexible in the axial direction of the stent. This U-shaped portion is not stretched and deformed so that Y-stenting is possible, and there is no such description. In fact, only two U-shaped portions described in the patent specification per rhombus can obtain an opening area sufficient for side branch access by balloon expansion and expansion of the above-described stent delivery catheter. Can not.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a stent according to the present invention will be described with reference to the drawings, but the present invention is not limited thereto.
[0021]
FIG. 2 is an example of the stent 3 according to the present invention (Example 1), and is a development view thereof. The stent 3 is formed in a substantially tubular body and can be extended radially outward of the substantially tubular body. Further, a substantially polygonal pattern 5 surrounded by a strut 4 which is a linear element has a circumferential shape. A plurality of stents arranged in the direction as well as in the axial direction. “It has a nearly polygonal shape” means that this polygonal shape includes triangles, rhombuses, rectangles, parallelograms, pentagons, or any polygonal shape, and the corners are not acute but curved. This means that rounded items are included.
[0022]
The polygonal pattern 5 has an original linear perimeter. This original linear perimeter is the length indicated by the thick line 6 in FIG. 3, and does not take into account the total length of the foldable local foldable portion 7 that will be described later, so-called, Represents the minimum linear perimeter of a polygonal pattern.
[0023]
The stent 3 of Example 1 is further expanded in the polygonal pattern portion 5 from the inside to the outside by balloon expansion of a stent delivery catheter, so that the peripheral length after being expanded is There are four local folding portions 7 that can be stretched and deformed so as to extend 1.3 times to 2.0 times the original linear perimeter.
[0024]
In the present embodiment, the shape of the stretchable local foldable portion 7 is a sine wave shape for two periods. However, as described above, in the polygonal pattern portion 5, from the inside to the outside. On the other hand, when the stent delivery catheter is expanded by balloon expansion or the like, the peripheral length after the expansion is expanded to 1.3 times to 2.0 times the original linear peripheral length 6. Anything is acceptable. On the other hand, the peripheral length after being expanded is the peripheral length of a pattern formed by extending one original linear peripheral length as shown in 8 of FIG.
[0025]
Here, when the stent delivery catheter is expanded by balloon expansion or the like, the peripheral length after the expansion is 1.3 to 2.0 times the original linear peripheral length 6. In order to obtain the force and satisfy the excellent scaffolding property, the original linear perimeter 6 of the polygonal pattern portion 5 is selected within the range described later, and one polygonal shape pattern portion 5 is selected. When the number of the local folding portions 7 that can be stretched and deformed is 3 or more, the perimeter after being expanded by balloon expansion or the like of the stent delivery catheter is 1.3% of the original linear perimeter. This is because if the width is increased in the range of 2 to 2.0 times, a sufficient opening area / perimeter can be obtained to access the side branch.
[0026]
The number of locally foldable portions 7 that can be stretched and deformed per one polygonal pattern portion 5 is preferably three or more, but more preferably the same as 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, radial force, and flexibility all uniform over the entire stent 3. In Example 1, since it is a parallelogram and has four sides, the number of locally folding portions that can be stretch-deformed is four.
[0027]
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 to satisfy an excellent scaffold. Is preferably 8.0 mm to 10.0 mm.
[0028]
Furthermore the area of the original opening of the polygonal shape pattern the same reason, after the stent expansion, it is desirably from 2.0 mm ² to 9.0 mm ^2, the more desirable is 3.0 mm ² to 6. 25 mm ² .
[0029]
FIG. 5 shows another embodiment in which the stretchable deformable folding portion is configured differently from the first embodiment (second embodiment), and the configuration of the stretchable deformable folding portion is different from that of the first embodiment. And shows the polygonal shape pattern.
[0030]
In other words, the stent 3 is formed in a substantially tubular body and can be extended outward in the radial direction of the substantially tubular body. Further, the pattern 5 having a substantially polygonal shape surrounded by the struts 4 that are linear elements is formed. A plurality of stents arranged in the circumferential direction as well as in the axial direction. In addition, “almost polygonal shape” means that the polygonal shape includes triangles, rhombuses, rectangles, parallelograms, pentagons, or any polygonal shape, and the corners are not acute but curved. This means that rounded items are included.
[0031]
The polygonal pattern 5 has an original linear perimeter. The original linear perimeter is the length indicated by the thick 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 minimum linear perimeter of a square shape pattern.
[0032]
The stent 3 in Example 2 is further expanded in the polygonal pattern portion 5 from the inner side toward the outer side by balloon expansion of the stent delivery catheter or the like, so that the peripheral length 8 after being expanded is increased. A relatively large number of locally deformable local folding portions 10 are provided so as to extend 1.3 times to 2.0 times of the original linear perimeter 9, The sum of the linear lengths in the side direction of the polygon is formed over 1/3 to 1 times the original linear perimeter of the polygonal shape pattern. The definition of the linear length in the side direction of the polygon of the locally foldable deformable portion 10 is as shown by the thick line 11 shown in FIG. 6 (meaning the sum of the thick line portions).
[0033]
In the second embodiment, the shape of the locally foldable portion 10 that can be deformed to stretch is substantially a continuous waveform. However, as described above, the polygonal pattern portion 5 has a shape that extends from the inside to the outside. On the other hand, when the stent delivery catheter is expanded by balloon expansion or the like, the perimeter after being expanded is 1.3 to 2.0 times the original linear perimeter 9. Anything is acceptable. In the second embodiment, the linear length 11 of the polygonal side direction of the stretchable local folding portion 10 is about ½ times the original linear peripheral length 9 of the polygonal shape pattern. Although it is strongly selected, it may be any number as long as it is in the range of 1/3 to 1 times. The stretchable and deformable folding portion 10 may be continuous around the polygon, or a plurality of discontinuous portions may be used.
[0034]
Here, the linear length 11 in the side direction of the polygon of the locally foldable deformable portion 10 is set to 1/3 times to 1 time the original linear peripheral length 9 of the polygonal shape pattern. First, in order to obtain a high radial force and to satisfy excellent scaffolding, the original linear perimeter 9 of the polygonal pattern portion 5 is selected within a range as described later, Assuming that when the stent delivery catheter is expanded by balloon expansion or the like, the peripheral length 8 after being expanded becomes 1.3 to 2.0 times the original linear peripheral length 9. The linear length 11 in the side direction of the polygon of the locally foldable deformable local folding portion 10 per one polygonal shape pattern portion 5 is the original linear perimeter 9 of the polygonal shape pattern. Enter the range of 1/3 to 1 times If, after the spread, because sufficient opening area / perimeter to access the side branch can be obtained.
[0035]
Moreover, the part which protruded in the axial direction different from the side direction of a polygon of the folding part 10 which can be extended and deformed cannot be enlarged. This is because when the stent is contracted and pre-mounted on the balloon of the stent delivery catheter, the protruding part overlaps with another locally-foldable deformable local folding part of the polygon adjacent in the circumferential direction. This is because it becomes impossible to pre-mount while maintaining a small outer diameter (low profile). From this point of view, the range indicated by the above numerical values is important.
[0036]
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 to satisfy an excellent scaffold. Is preferably 8.0 mm to 10.0 mm.
[0037]
Furthermore the area of the original opening of the polygonal shape pattern the same reason, after the stent expansion, it is desirably from 2.0 mm ² to 9.0 mm ^2, the more desirable is 3.0 mm ² to 6. 25 mm ² .
[0038]
The stents disclosed in the above two embodiments have a plurality of polygonal patterns 5 in the circumferential direction and the axial direction, so that a high radial force can be maintained and at the same time excellent scaffolding properties. Further, in the polygonal pattern portion 5, the perimeter after being expanded by balloon expansion or the like of the stent delivery catheter from the inside to the outside is 1% of the original linear perimeter. In Example 2, three or more local portions that can be stretched and deformed are provided in each polygonal pattern so as to expand to 3 to 2.0 times. By forming the linear length 11 in the side direction of the polygonal local portion over 1/3 to 1 times the original linear length 9 of the polygonal shape pattern, the polygonal shape Expansion of the balloon of another stent delivery catheter placed in the side branch through the pattern can greatly deform the perimeter of the polygonal pattern, thus providing access to the branch vessel and Y-step. Bet is to become possible.
[0039]
【The invention's effect】
According to the present invention, while maintaining the advantages of the closed type, it solves the disadvantages at the same time and has only the advantages without generating the disadvantages of the open type, that is, a high radial force, excellent scaffolding It is possible to provide a closed type stent that enables Y stent to branch blood vessels while maintaining the above.
[Brief description of the drawings]
FIG. 1 is a diagram showing a Y stent or Y stenting. FIG. 2 is a developed view of a stent showing Example 1 of the present invention. FIG. 3 is a polygonal shape showing an original linear perimeter in Example 1. FIG. 4 is a diagram showing the perimeter after being spread out. FIG. 5 is a diagram of a polygonal shape pattern of a stent showing Example 2 of the present invention. FIG. Of the polygonal shape pattern showing the linear length of the local direction of the polygon in the side direction [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Main blood vessel 2 Side branch blood vessel 3 Stent 4 Strut 5 The pattern of the substantially polygonal shape enclosed by the strut 6 Original linear perimeter length of this polygonal shape pattern 7 The local folding part 8 which can be extended and deformed Polygonal shape Perimeter 9 after the pattern is spread 9 Original linear perimeter 10 of the polygonal shape pattern Stretchable deformable local fold portion 11 In the stretchable deformable portion, the polygonal linear direction of the side of the polygon Length 101 1st stent (detained in main vessel)
102 Second stent (detained in side branch vessel)
103 Proximal portion of main blood vessel 104 Distal portion of main blood vessel 1

Claims (4)

A substantially polygonal pattern that is formed in a substantially tubular body and is extensible radially outward of the substantially tubular body and surrounded by struts that are linear elements is formed in the circumferential direction and the axial direction. A plurality of side-by-side stents, and the stent has a strut series formed by connecting a plurality of struts in the circumferential direction, and the strut series includes one end portion, the other end portion, and a plurality of folded portions. The polygonal shape pattern has a linear perimeter (original linear perimeter), and the polygonal pattern is spread from the inside toward the outside. Thus, the stretchable local folding part is expanded into one polygonal shape so that the perimeter after being expanded is 1.3 to 2.0 times the original linear perimeter. per pattern, three or more to Yes, the Strut connecting excluding strut interconnection located at an axial end of the tent, one end, the other end, and that all of the folded portion is connected to one end of the deformable locally folded portion extends respectively Features a stent.   2. The stent according to claim 1, wherein the number of locally deformable portions that can be stretched and deformed per one polygonal shape pattern is the same as the number of sides of the polygon. A substantially polygonal pattern that is formed in a substantially tubular body and is extensible radially outward of the substantially tubular body and surrounded by struts that are linear elements is formed in the circumferential direction and the axial direction. A plurality of side-by-side stents, and the stent has a strut series formed by connecting a plurality of struts in the circumferential direction, and the strut series includes one end portion, the other end portion, and a plurality of folded portions. The polygonal shape pattern has a linear perimeter (original linear perimeter), and the polygonal pattern is spread from the inside toward the outside. Thus, the stretched deformable portion has a stretchable deformable portion so that the perimeter length after being expanded is 1.3 to 2.0 times the original linear perimeter length. The side of the polygon of the folding part is linear The sum of, are formed over 1/3 to 1 times the original linear perimeter of the polygon shape pattern, the struts connecting excluding strut interconnection located at an axial end of the stent, the A stent characterized in that one end portion, the other end portion, and all the folded portions are respectively connected to one end portion of a locally folded portion that is stretchable and deformable . The original linear perimeter of the polygonal pattern is 6.0 mm to 12.0 mm, and the area of the opening surrounded by the perimeter after being expanded after stent expansion is 2.0 mm ^{2 to} 9 It claims 1 to 3 wherein the stent, characterized in that it is .0mm ^2.

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