JP7260525B2 - stent - Google Patents

Description

The present invention relates to stents.

A stent is indwelled in an expanded state in a stenosis that has occurred in a biological lumen such as a blood vessel, and maintains the biological lumen in an open state.

Since a stent is placed in a biological lumen such as a blood vessel, it is required to be flexible so as to follow the shape of the inner wall of the biological lumen. For example, Patent Document 1 below discloses that, in order to improve flexibility, a linear body forming a cylindrical shape is connected to adjacent portions of the linear body in the axial direction, and is broken by indwelling in a biological lumen. A stent is disclosed having a decoupling weakened portion.

WO2013/065218

Although the stent as disclosed in Patent Document 1 is excellent in flexibility, it has the problem that it can re-shrink after being indwelled.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a stent that is flexible and capable of suppressing re-shrinkage after being placed in a biological lumen.

A stent according to the present invention for achieving the above object is a stent provided with linear struts forming an outer periphery of a cylindrical shape with gaps formed therein, wherein the struts are imaginary struts parallel to the axis of the cylindrical shape. A linear first strut portion forming a first region, which is one region when the stent is divided into two by the horizontal plane of , and a first region , which is the other region when the stent is divided into two by the horizontal plane It is composed only of linear second strut portions forming two regions, the first region being a region extending from the distal end to the proximal end of the stent in the axial direction, and the second region being the stent. It is a region extending from the distal end to the proximal end in the axial direction , the second strut portion forms a region of half or more around the axis of the cylindrical shape, and the second strut portion is larger than the first strut portion. It is characterized by high rigidity.

The stent according to the present invention can exhibit flexibility due to the relatively low stiffness of the first strut portion. In addition, the stent according to the present invention can suppress re-shrinkage after placement due to the relatively rigid second strut portion. Thus, according to the present invention, it is possible to provide a stent that is flexible and capable of suppressing re-shrinkage after being placed in a biological lumen.

1 is a perspective view showing a stent according to a first embodiment of the invention; FIG. 1 is an axial cross-sectional view of a stent according to a first embodiment of the present invention; FIG. FIG. 4 is an axis-orthogonal cross-sectional view showing a stent according to modification 1; FIG. 10 is an axis-perpendicular cross-sectional view showing a stent according to modification 2; FIG. 12 is an axis-orthogonal cross-sectional view showing a stent according to modification 3; FIG. 4 is a perspective view showing a stent according to a second embodiment of the invention; FIG. 6 is a developed view obtained by linearly cutting a portion of the outer periphery of the stent according to the second embodiment of the present invention along the axial direction and developing the stent;

Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. The following description does not limit the technical scope or the meaning of terms described in the claims. Also, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may differ from the actual ratios.

(First embodiment)
1 and 2 are diagrams showing a stent 100 according to a first embodiment of the invention. In this specification, the direction (longitudinal direction) in which the axis x of the stent 100 extends is defined as "axial direction d" as shown in FIG. In addition, in the axial direction d, the side that is first introduced into the biological lumen is defined as the "distal end side", and the side opposite to the distal end side is defined as the "proximal end side". Also, the direction around the axis x of the stent 100 is referred to as "circumferential direction θ". A direction perpendicular to the axis x of the stent 100 is referred to as a "radial direction r" as shown in FIG.

The stent 100 according to the first embodiment is used to dilate a constriction formed by plaque or the like in a cerebral blood vessel (corresponding to a “biological lumen”).

The stent 100 according to the first embodiment has linear struts 110 forming a cylindrical outer periphery with a plurality of gaps as shown in FIG. The plurality of gaps are arranged in a predetermined pattern to separate adjacent portions of strut 110 .

The struts 110, as shown in FIG. 2, form a first strut portion 111 forming a first region 110a about the axis x of the stent 100 and a second region 110b about the axis x different from the first region 110a. , and a second strut portion 112 that is stiffer than the first strut portion 111 .

Thus, stent 100 comprises first strut portion 111 and second strut portion 112 having different stiffnesses. Therefore, the stent 100 can exhibit flexibility due to the relatively low stiffness of the first strut portions 111 . Therefore, the stent 100 can easily follow the shape of the blood vessel and reduce the burden on the blood vessel. In addition, the relatively rigid second strut portion 112 can suppress re-contraction of the stent 100 even if it receives a pushing force from the blood vessel wall after expansion (that is, the recoil of the stent 100 can be suppressed). ). In particular, since cerebral blood vessels are thinner and easier to cut than other sites such as coronary arteries, the stent 100 placed in cerebral blood vessels is more suitable than stents placed in blood vessels in other sites such as coronary arteries. A high degree of flexibility is also required. On the other hand, the stent 100 is also required to suppress re-shrinkage after expansion. In the stent 100 according to this embodiment, the first strut portion 111 and the second strut portion 112 can favorably achieve both flexibility and suppression of re-shrinkage.

In this embodiment, as shown in FIG. 2, the first region 110a formed by the first strut portions 111 is one region when the stent 100 is divided by an imaginary horizontal plane s passing through the axis x of the stent 100. (lower region in FIGS. 1 and 2). 1 and 2, the first region 110a corresponds to the half of the circumference of the stent 100 around the axis x and the region extending from the distal end to the proximal end of the stent 100 in the axial direction d.

In this embodiment, the second region 110b formed by the second strut portions 112 is the other region when the stent 100 is divided by an imaginary horizontal plane s passing through the axis x of the stent 100, as shown in FIG. (upper region in FIGS. 1 and 2). 1 and 2, the second region 110b corresponds to the half of the circumference of the stent 100 around the axis x and the region extending from the distal end to the proximal end of the stent 100 in the axial direction d. In this way, the second strut portion 112 is provided from the distal end to the proximal end of the stent 100 in the axial direction d. Re-shrinkage can be suppressed.

Note that the first strut portion 111 and the second strut portion 112 are not particularly limited as long as they are provided in different regions around the axis x. For example, first strut section 111 may form more than half the area of stent 100 about axis x, and second strut section 112 may form less than half the area of stent 100 about axis x. However, from the viewpoint of suppressing re-contraction of the expanded stent 100, it is preferable that the second strut section 112 is provided in an area of not less than half to about 80% of the stent 100 in the circumferential direction θ. If the second struts 112 form more than half the area of the stent 100 around axis x, even if the first struts 111 are likely to re-collapse after expansion, the second struts 112 will More than half the lumen of stent 100 can be maintained.

In this embodiment, the first strut portion 111 and the second strut portion 112 are formed in a mesh shape, as shown in FIG. As shown in FIG. 2, in the present embodiment, the width w1 of the linear portion of the first strut portion 111 and the width w2 of the linear portion of the second strut portion 112 (the length along the circumferential direction θ) are the same. It is configured to be In this embodiment, the thicknesses t1 and t2 (the length along the radial direction r) of the first strut portion 111 and the second strut portion 112 are configured to be the same. However, the shape of the strut 110 may not be a mesh shape, but may be a shape in which a plurality of annular portions folded back in a wave shape as shown in FIG. 6 are arranged in the axial direction d.

In order to make the rigidity of the second strut portion 112 higher than the rigidity of the first strut portion 111, in the present embodiment, the second strut portion 112 is made of a material having a higher hardness than the constituent material of the first strut portion 111. ing. The hardness of the constituent material of the first strut portion 111 is not particularly limited, but from the viewpoint of imparting flexibility to the stent 100 to the extent that it follows the shape of the inner wall of the biological lumen, Vickers hardness (based on JIS Z2244, hereinafter referred to as ), it is preferably about 10 to 100 Hv. The hardness of the constituent material of the second strut portion 112 is not particularly limited, but from the viewpoint of suppressing re-shrinkage of the stent 100 placed in the biological lumen in an expanded state, the Vickers hardness is about 100 to 500 Hv. is preferred.

The constituent material of the first strut portion 111 is not particularly limited as long as it is biocompatible and has a lower hardness than the second strut portion 112. Examples thereof include stainless steel. The constituent material of the second strut portion 112 is not particularly limited as long as it is biocompatible and has higher hardness than the first strut portion 111. Examples include superelastic alloys such as NiTi and CoCr alloys. Cobalt-based alloys may be mentioned. A drug coating layer containing a predetermined drug or a drug carrier for carrying the drug may be provided on the outer surface of the strut 110 .

The strut 110 is provided with a marker 113 visible under X-ray fluoroscopy, as shown in FIG.

In this embodiment, the marker 113 is provided at the base end of the second strut portion 112 and at the intermediate portion of the second strut portion 112 in the circumferential direction θ. This allows the operator to grasp the position of the second strut portion 112 in the circumferential direction θ under X-ray fluoroscopy, and to place the second strut portion 112 at an appropriate position in the body lumen. For example, when a plaque or the like occurs at a deviated position in the circumferential direction of the inner wall of the biological lumen, the operator arranges the second strut portion 112 so as to face the portion of the inner wall of the biological lumen where the plaque is generated. be able to.

However, the region where the marker 113 is provided is not particularly limited as long as the operator can grasp the position of the first strut portion 111 in the circumferential direction θ or the position of the second strut portion 112 in the circumferential direction θ under X-ray fluoroscopy. For example, the marker 113 may be provided at the distal end portion of the first strut portion 111 or may be provided at the proximal end portion or the distal end portion of the second strut portion 112 in this embodiment.

The constituent material of the marker 113 is not particularly limited as long as it includes a material having a contrastability that is visible under X-ray fluoroscopy. Examples of such materials include, but are not particularly limited to, metals such as gold, platinum, and tungsten, and materials including radiopaque materials such as alloys containing these metals.

Although the stent 100 is not particularly limited, it can be manufactured, for example, by the procedure shown below. First, two mesh-like cylinders made of materials having different hardnesses are produced. Next, each cylindrical body is cut along the axial direction by a laser or the like to produce a semi-cylindrical body. Next, semi-cylindrical bodies made of materials having different hardnesses are joined together by welding or the like. The stent 100 is thus produced.

As described above, the stent 100 according to the first embodiment has a tubular shape with gaps. The stent 100 has a linear first strut portion 111 that forms a first region 110a around the axis x of the tubular shape, and a second region 110b that is different from the first region 110a around the axis x of the tubular shape. and a linear second strut portion 112 . The second strut portion 112 has higher rigidity than the first strut portion 111 .

According to the stent 100 according to the above embodiment, the stent 100 can exhibit flexibility due to the relatively low stiffness of the first strut portions 111 . Further, re-shrinkage after expansion can be suppressed by the second strut portion 112 having relatively high rigidity. Thus, it is possible to provide the stent 100 that is flexible and capable of suppressing re-contraction after expansion in a biological lumen.

Also, the second strut portion 112 is made of a material having a higher hardness than the material of the first strut portion 111 . Therefore, the rigidity of the second strut portion 112 can be made higher than that of the first strut portion 111 .

In addition, the second strut portion 112 forms an area of more than half of the tubular shape around the axis x. Therefore, even if the first strut portion 111 is about to contract again after the stent 100 is expanded, the second strut portion 112 can maintain more than half of the lumen of the stent 100 .

Further, one of the first strut portion 111 and the second strut portion 112 is provided with a marker 113 having a contrastability that is visible under X-ray fluoroscopy. Therefore, the operator grasps the position of the first strut portion 111 or the second strut portion 112 in the circumferential direction θ under X-ray fluoroscopy, and arranges the first strut portion 111 or the second strut portion 112 at an appropriate position. can do.

(Modification)
3 to 5 are diagrams for explaining stents 100a to 100c according to modifications. Each of the stents 100a to 100c has a marker 113 like the stent 100 according to the first embodiment, but the description thereof will be omitted.

In the stent 100 according to the first embodiment, the first strut portion 111 and the second strut portion 112 are provided with different rigidity by making the materials constituting the first strut portion 111 and the second strut portion 112 different in hardness. configured to However, the method of varying the rigidity is not limited to the above.

For example, as shown in FIG. 3, in the stent 100a according to Modification 1, the width w2 (the length along the circumferential direction θ) of the linear portion of the second strut portion 112a is the width of the linear portion of the first strut portion 111a. It is configured to be larger than the width w1. Thereby, the rigidity of the second strut portion 112a can be made higher than that of the first strut portion 111a.

For example, as shown in FIG. 4, in a stent 100b according to Modification 2, the thickness t2 (the length along the radial direction r) of the second strut portions 112b is made larger than the thickness t1 of the first strut portions 111b. Configure. Thereby, the rigidity of the second strut portion 112b can be made higher than the rigidity of the first strut portion 111b.

Moreover, although the stent 100 according to the first embodiment has been described as having a cylindrical shape, the external shape of the stent 100 is not particularly limited as long as it is cylindrical (having a lumen).

For example, as shown in FIG. 5, in the stent 100c according to Modified Example 3, the second strut portion 112c has an arc-shaped external shape in the cross section perpendicular to the axis, and the first strut portion 111c has a linear shape in the cross section perpendicular to the axis. may be configured to include By configuring in this way, it is possible to suppress expansion of the stent 100c to the extent that the vascular wall is expanded excessively.

It should be noted that, in Modification 3, as in the first embodiment, the second strut portion 112c is made of a material having a hardness higher than that of the first strut portion 111c. Further, in Modification 3, the second strut portion 112c extends beyond the imaginary horizontal plane s passing through the central axis of the arc of the second strut portion 112c (the axis x of the stent 100c). That is, the second strut portion 112c is provided over more than half of the stent 100c around the axis x. Therefore, even if the first strut portion 111c is about to contract again after expansion, the second strut portion 112c can maintain more than half of the lumen of the stent 100c.

(Second embodiment)
6 and 7 are diagrams for explaining the stent 200 according to the second embodiment.

The stent 200 according to the second embodiment differs from the stent 100 according to the above embodiment in that it does not have a mesh structure. A stent 200 according to the second embodiment will be described below.

The stent 200 of the second embodiment has linear struts 210 forming a spaced cylindrical shape, as shown in FIG.

As shown in FIGS. 6 and 7, the strut 210 includes a plurality of annular portions 211 that are folded back in a wave shape and extend in the circumferential direction θ to form an endless annular shape. The plurality of annular portions 211 are arranged in the axial direction d. The strut 210 includes a plurality of link portions 212 that connect adjacent portions of the annular portion 211 in the axial direction d.

Struts 210 are shown in FIGS. 6 and 7 and include a first strut portion 213 forming a first region 210a about axis x of stent 200 and a second strut portion 213 different from first region 210a about axis x of stent 200. a second strut portion 214 forming the region 210b and having a higher rigidity than the first strut portion 213;

In order to make the rigidity of the second strut portion 214 higher than the rigidity of the first strut portion 213, in the present embodiment, the number of link portions 212 provided on the second strut portion 214 is It is configured to be larger than the number of link portions 212 . Furthermore, in the present embodiment, the first strut portion 213 has an open cell structure in which some portions 213 a of a plurality of portions adjacent in the axial direction d are connected by link portions 212 . That is, in the first strut portion 213 , a portion 213 b of adjacent portions in the axial direction d is not connected by the link portion 212 . On the other hand, the second strut portion 214 has a closed cell structure in which all adjacent portions in the axial direction d are connected by the link portion 212 .

The materials forming the first strut portion 213, the second strut portion 214, and the link portion 212 are not particularly limited as long as they are biocompatible. Examples of such materials include, but are not limited to, stainless steel, cobalt-based alloys such as CoCr, and superelastic alloys such as NiTi.

As described above, the stent 200 according to the second embodiment has a plurality of link portions 212 connecting adjacent portions of the first strut portion 213 and the second strut portion 214 in the axial direction d. The number of link portions 212 provided on the second strut portion 214 is greater than the number of link portions 212 provided on the first strut portion 213 . Thereby, the rigidity of the second strut portion 112b can be made higher than that of the first strut portion 111a.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims.

For example, the stent according to the present invention can be applied not only to cerebrovascular stents, but also to coronary artery stents and lower extremity stents.

Further, in the above-described embodiment and modified example, as a method of adjusting the rigidity of the first strut portion and the second strut portion, the hardness of the material of the first strut portion and the second strut portion, the width, the thickness, and the number of link portions are adjusted. It is described that each is adjusted. However, in order to make the rigidity of the second strut section higher than that of the first strut section, several items among the hardness of the material of the first strut section and the second strut section, width, thickness, and the number of link sections are adjusted. You may

In addition, in the above-described embodiment and modified example, a form in which two regions with different rigidity are provided around the axis of the stent has been described. good.

Further, in the above-described embodiment and modified example, the configuration in which the first strut portion and the second strut portion having different rigidity are simply connected is explained, but the rigidity gradually increases between the first strut portion and the second strut portion. It may be configured to change.

This application is based on Japanese Patent Application No. 2018-059885 filed on March 27, 2018, the disclosure of which is incorporated by reference in its entirety.

100, 100a, 100b, 100c, 200 stents,
110 struts,
110a first region,
110b second region,
111, 111a, 111b, 111c, 213 first strut portion,
112, 112a, 112b, 112c, 214 second strut portion,
113 markers,
212 link part,
the x-axis,
d-axis direction,
θ circumferential direction,
r radial direction,
t1 thickness of the first strut portion,
t2 thickness of the second strut portion,
w1 width of the linear portion of the first strut portion;
w2 Width of the linear portion of the second strut portion.

Claims (7)

A stent comprising linear struts forming an outer periphery of a tubular shape with gaps formed therein,
The strut is
A linear first strut portion forming a first region, which is one region when the stent is divided into two by an imaginary horizontal plane parallel to the axis of the tubular shape , and the horizontal plane divides the stent into two. It is composed only of a linear second strut portion that forms a second region that is the other region when divided into
The first region is a region extending from the distal end to the proximal end of the stent in the axial direction, and the second region is a region extending from the distal end to the proximal end of the stent in the axial direction,
The second strut part forms an area of half or more around the axis of the cylindrical shape,
The stent, wherein the second strut portion has higher rigidity than the first strut portion. 2. The stent according to claim 1, wherein the second strut portion is made of a material having a higher hardness than the material forming the first strut portion. 3. The stent according to claim 1 or 2, wherein the width of the linear portion of the second strut portion is greater than the width of the linear portion of the first strut portion. The stent according to any one of claims 1 to 3, wherein the thickness of the second strut portion is greater than the thickness of the first strut portion. having a plurality of link portions connecting adjacent portions of the first strut portion and the second strut portion in the axial direction of the cylindrical shape;
The stent according to any one of claims 1 to 4, wherein the number of link portions provided on the second strut portion is greater than the number of link portions provided on the first strut portion. The marker according to any one of claims 1 to 5, wherein either one of the first strut portion and the second strut portion is provided with a marker having a contrastability that is visible under X-ray fluoroscopy. stent. the second strut portion has an arc-shaped outer shape in an axis-perpendicular cross section,
The stent according to any one of claims 1 to 6 , wherein the first strut portion has a linear shape in an axis-perpendicular cross-section .

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