JP4808331B2 - 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.
[0003]
These can be classified into those that are expanded by a balloon mounted with a stent and those that are expanded by removing a member that suppresses expansion from the outside. Among these, the stent expanded by the balloon is used by adjusting the expansion pressure according to the state of the tubular tissue to be expanded and the mechanical strength of the stent.
[0004]
In recent years, these stents have been frequently used especially for angioplasty of the heart and carotid artery.
[0005]
Japanese Examined Patent Publication No. 4-6377 describes a stent that, after being expanded, has a rhombus shape with continuous components. This stent had the advantage that it was very resistant to the forces that the blood vessels were trying to contract. However, since this stent lacks axial flexibility when not expanded, it is very difficult to insert into a bent blood vessel, and the inside of the blood vessel may be damaged. In addition, since there is a lack of flexibility in the axial direction even after expansion, there is a problem that, when transplanted into a bent blood vessel, excessive stimulation is given to the blood vessel to promote restenosis. Further, when expanding, the stent axial length contracts, and it is difficult to expand the entire stenosis of the blood vessel.
[0006]
Japanese Patent Publication No. 7-24688 describes a stent in which a wire is deformed in a zigzag shape and spirally wound so as to be further cylindrical. This stent is rich in axial flexibility and excellent in insertion into a bent blood vessel. However, there is a problem that the resistance to the force with which the blood vessel attempts to contract is very small, and the blood vessel tends to contract due to the pressure with which the blood vessel attempts to contract. In addition, when expanding to the target diameter, it is difficult to uniformly expand the struts of the stent, and there is a problem that it is easy to make a part that expands greatly even within the same circumference and a part that does not expand much. there were. If such uneven expansion is performed, the endothelial tissue of the tubular tissue protrudes greatly from the portion where the struts are largely opened, which may cause restenosis. In addition, when the non-uniform expansion is severe, it may become impossible to maintain a perfect circle in cross section. In order to solve this problem, a method of folding a balloon for mounting a stent has been devised, but it is still difficult to uniformly expand the balloon. In another method, attempts have been made to attach a member that easily expands uniformly to the balloon surface, but the balloon profile becomes large, making it difficult to deliver the stent to the target site. The problem of becoming.
[0007]
[Problems to be solved by the invention]
In view of these circumstances, the present invention intends to solve the problem that the stent is flexible in the axial direction before stent expansion, and the stent axial length does not contract during stent expansion, and the blood vessel contracts after expansion. It is an object of the present invention to provide a stent that has a very large resistance to the force and can expand the struts of the stent uniformly.
[0008]
[Means for Solving the Problems]
[1] it is formed into a substantially tubular body and a expandable stent in the radial direction from the inside of the substantially tubular body, Ri substantially parallelogram der primitives constituting the stent, as the parallelogram, the short There are at least first to fourth parallelograms each having a side and a long side,
The short side of the first parallelogram touches the long side of the second parallelogram,
The short side of the second parallelogram touches the long side of the third parallelogram,
The short side of the third parallelogram touches the long side of the fourth parallelogram,
The short side of the fourth parallelogram touches the long side of the first parallelogram,
The first parallelogram and the third parallelogram have the same long side direction,
The second parallelogram and the fourth parallelogram have the same long side direction,
The first parallelogram and the second parallelogram have different long sides,
The second parallelogram and the fourth parallelogram are connected in the axial direction of the stent;
The first parallelogram and the third parallelogram are separated from each other in the circumferential direction of the stent by sandwiching the second parallelogram or the fourth parallelogram .
[0010]
[2] is substantially parallel sides of the parallelogram elements in the stent axial direction in front scan stent expansion, each side of the substantially parallelogram element has an angle relative to the stent axis direction after the stent expansion The stent according to [1] is provided.
[0011]
[ 3 ] The substantially parallelogram elements are composed of substantially straight struts and substantially corrugated struts, and the substantially corrugated struts are arranged at at least four vertices of the parallelogram, respectively [1] Alternatively, a [ 2 ] stent is provided.
[0012]
[ 4 ] The stent according to [ 3 ] in which substantially parallelograms having different areas are arranged in the stent axial direction.
[0013]
[ 5 ] A stent according to [ 3 ] or [ 4 ] is provided in which different strut widths, strut thicknesses, or both are combined in the axial direction of the stent.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a stent according to the present invention will be described with reference to the drawings.
[0015]
FIG. 1 is a plan view of a stent 1 according to the present invention. The stent 1 is a stent that is formed in a substantially tubular body and is radially expandable from the inside of the substantially tubular body, and the basic elements constituting the stent are substantially parallelograms, and the substantially parallelogram elements are staggered. The stent 1 is configured in combination. The term “substantially parallelogram elements” combined here means that there are substantially parallelogram elements arranged in different directions when viewed in a plan view, and these elements are combined with each other. To tell. In order to adjust the both ends of the stent to a radial cross section substantially orthogonal to the stent axial direction, only the both ends of the stent may include elements other than the substantially parallelogram elements.
[0016]
Composing from substantially parallelogram elements can reduce the number of connection points compared to conventional stents, and can provide high flexibility before stent expansion, and substantially parallelogram elements are staggered after stent expansion. When combined with this, it has a high radial force. That is, the angle formed between the substantially parallelogram element and the stent axis direction before and after expansion of the stent changes, and the angle formed between the substantially parallelogram element and the stent axis direction before expansion is substantially equal to that after expansion. The angle formed by the parallelogram element and the stent axial direction is smaller. Therefore, in addition to being able to reduce the number of connection points compared with conventional stents, it has both the high performance in the axial direction before stent expansion and high radial force after stent expansion. it can. Here, the radial force represents a resistance to a force that the blood vessel tends to contract. When the radial force is low, the resistance to the force that the blood vessel tries to contract is low, and the stent contracts against the force that the blood vessel tries to contract, obstructing the blood flow, and in the worst case, it causes restenosis And a high radial force is required.
[0017]
Since the stent 1 has the substantially parallelogram elements arranged uniformly, the stent struts can be expanded uniformly.
[0018]
If the number of substantially parallelograms arranged in the axial direction of the stent 1 is reduced, high stent axial flexibility is obtained, but the radial force is lowered. Further, if the number of the substantially parallelograms is increased, a high radial force can be obtained, but the stent axial flexibility is lowered. In order to obtain a suitable stent axial flexibility and high radial force, the number of substantially parallelograms arranged in the axial direction of the stent 1 is 7 or more and 11 or less per 20 mm in the stent axial length, Preferably they are 8 or more and 10 or less.
[0019]
FIG. 2 is a plan view of the stent 2 according to the present invention. The stent 2 is a stent that is formed in a substantially tubular body and is radially expandable from the inside of the substantially tubular body, wherein the basic elements constituting the stent are substantially parallelograms, and the substantially parallelogram elements are staggered. The substantially parallelogram-shaped element is composed of a substantially straight strut 21 and a substantially wavy strut 22. The term “substantially parallelogram elements” combined here means that there are substantially parallelogram elements arranged in different directions when viewed in a plan view, and these elements are combined with each other. To tell. In order to adjust the both ends of the stent to a radial cross section substantially orthogonal to the stent axial direction, only the both ends of the stent may include elements other than the substantially parallelogram elements.
[0020]
Composing from substantially parallelogram elements can reduce the number of connection points compared to conventional stents, and can provide high flexibility before stent expansion, and substantially parallelogram elements are staggered after stent expansion. When combined with this, it has a high radial force. That is, the angle formed between the substantially parallelogram element and the stent axis direction before and after expansion of the stent changes, and the angle formed between the substantially parallelogram element and the stent axis direction before expansion is substantially equal to that after expansion. The angle formed by the parallelogram element and the stent axial direction is smaller. Therefore, in addition to being able to reduce the number of connection points compared with conventional stents, it has both the high performance in the axial direction before stent expansion and high radial force after stent expansion. it can.
[0021]
In addition, since the substantially parallelogram element has the substantially corrugated strut 22, higher stent axial flexibility can be obtained before the stent expansion, and the substantially corrugated strut 22 expands and contracts in the axial direction. The contraction of the axial length in the stent can be prevented.
[0022]
Since the stent 2 has the substantially parallelogram elements arranged uniformly, the stent struts can be expanded uniformly.
[0023]
If the number of substantially parallelograms arranged in the axial direction of the stent 2 is reduced, high stent axial flexibility is obtained, but the radial force is lowered. Further, if the number of the substantially parallelograms is increased, a high radial force can be obtained, but the stent axial flexibility is lowered. In order to obtain a suitable stent axial flexibility and high radial force, the number of substantially parallelograms arranged in the axial direction of the stent 2 is 5 or more and 9 or less per 20 mm in the axial length of the stent. Preferably they are 6 or more and 8 or less.
[0024]
FIG. 3 is a plan view of the stent 3 according to the present invention after the stent is expanded, and FIG. 4 is a plan view of the stent 3 before the expansion. The stent 3 is a stent that is formed in a substantially tubular body and is radially expandable from the inside of the substantially tubular body, wherein the basic elements constituting the stent are substantially parallelograms, and the substantially parallelogram elements are staggered. The substantially parallelogram-shaped element is composed of a substantially straight strut 31 and a substantially wavy strut 32. The term “substantially parallelogram elements” combined here means that there are substantially parallelogram elements arranged in different directions when viewed in a plan view, and these elements are combined with each other. To tell. In order to adjust the both ends of the stent to a radial cross section substantially orthogonal to the stent axial direction, only the both ends of the stent may include elements other than the substantially parallelogram elements. Further, in the stent 3, each side of the substantially parallelogram element is substantially parallel to the stent axis direction before the stent expansion (FIG. 4), and each side of the substantially parallelogram element is in the stent axis direction after the stent expansion. It has an angle to it (Fig. 3).
[0025]
Composing from substantially parallelogram elements can reduce the number of connection points compared to conventional stents, and can provide high flexibility before stent expansion, and substantially parallelogram elements are staggered after stent expansion. When combined with this, it has a high radial force. That is, the angle formed between the substantially parallelogram element and the stent axis direction before and after the expansion of the stent changes, and each side of the approximately parallelogram element is approximately parallel to the stent axis direction before the stent expansion (FIG. 4). ), After the stent expansion, each side of the substantially parallelogram element has an angle with respect to the stent axial direction, so that it has a high stent axial flexibility before stent expansion compared to the conventional stent, The two performances of high radial force after stent expansion can be achieved.
[0026]
In addition, since the substantially parallelogram element has the substantially corrugated struts 32, it is possible to obtain higher stent axial flexibility before stent expansion, and the substantially corrugated struts 32 expand and contract in the axial direction, thereby expanding the stent. The contraction of the axial length in the stent can be prevented.
[0027]
Since the stent 3 has the substantially parallelogram elements arranged uniformly, the stent struts can be expanded uniformly.
[0028]
If the number of substantially parallelograms arranged in the axial direction of the stent 3 is reduced, high stent axial flexibility is obtained, but the radial force is lowered. Further, if the number of the substantially parallelograms is increased, a high radial force can be obtained, but the stent axial flexibility is lowered. In order to obtain a suitable stent axial flexibility and high radial force, the number of substantially parallelograms arranged in the axial direction of the stent 2 is 5 or more and 9 or less per 20 mm in the axial length of the stent. Preferably they are 6 or more and 8 or less.
[0029]
In the stent according to the present invention, by arranging substantially parallelograms having different areas in the stent axial direction, flexibility and radial force different in the stent axial direction can be obtained, and each area of the substantially parallelogram is It can be made suitable according to the diameter and length of the stent.
[0030]
The stent according to the present invention can obtain different flexibility and radial force in the stent axial direction by combining different strut widths, strut thicknesses, or both in the stent axial direction, and the strut width, The thickness of the strut can be made suitable for the diameter and length of the stent.
[0031]
The stent according to the present invention can be made of a metal such as stainless steel, Ni—Ti alloy, Cu—Al—Mn alloy having appropriate rigidity and elasticity, or a polymer material having appropriate rigidity and elasticity. .
[0032]
The stent according to the present invention may be finished by any of plating of a protective material, impregnation with a pharmaceutical agent and covering with a material.
[0033]
In the stent according to the present invention, a drug capable of suppressing intimal thickening, a drug capable of suppressing the proliferation of vascular smooth muscle cells, an antiplatelet drug (aspirin, heparin, antithrombin preparation, dipyrimidamol, etc.), an anti-inflammatory drug ( It is possible to attach and coat steroids.
[0034]
【The invention's effect】
According to the present invention, the stent struts can be expanded evenly by being flexible in the axial direction and having a stent axial length that is not contracted during expansion, and that has a great resistance to the force of the blood vessel to contract. A stent is provided that is capable of
[Brief description of the drawings]
FIG. 1 is a plan view of a stent 1 according to the present invention. FIG. 2 is a plan view of a stent 2 according to the present invention. FIG. 3 is a plan view of a stent 3 according to the present invention after stent expansion. Plan view before expansion of the stent 3 [Explanation of symbols]
21, 31: substantially straight struts 22, 32: substantially corrugated struts

Claims (5)

Is formed in a substantially tubular body and a expandable stent in the radial direction from the inside of the substantially tubular body, the basic elements constituting the stent Ri substantially parallelogram der, as the parallelogram, the short side and a long There are at least first to fourth parallelograms each having a side;
The short side of the first parallelogram touches the long side of the second parallelogram,
The short side of the second parallelogram touches the long side of the third parallelogram,
The short side of the third parallelogram touches the long side of the fourth parallelogram,
The short side of the fourth parallelogram touches the long side of the first parallelogram,
The first parallelogram and the third parallelogram have the same long side direction,
The second parallelogram and the fourth parallelogram have the same long side direction,
The first parallelogram and the second parallelogram have different long sides,
The second parallelogram and the fourth parallelogram are connected in the axial direction of the stent;
The first parallelogram and the third parallelogram are spaced apart from each other in the circumferential direction of the stent with the second parallelogram or the fourth parallelogram interposed therebetween . Scan tent extension each side of the front parallelogram elements in is substantially parallel to the stent axis direction, characterized in that each side of the substantially parallelogram element has an angle relative to the stent axis direction after the stent expansion The stent according to claim 1. Substantially parallelogram element is composed of a substantially straight strut and a substantially waveform strut, generally waveform struts, according to claim 1 or 2, characterized in that are arranged on the four vertices of at least said parallelogram Stent. The stent according to claim 3 , wherein substantially parallelograms having different areas are arranged in the stent axial direction. The stent according to claim 3 or 4 , wherein different strut widths, strut thicknesses, or both are combined in the stent axial direction.

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