JP2019195673A - Stent - Google Patents

Abstract

To provide a stent having a novel structure, capable of achieving in a higher degree, a characteristic required for the stent, by providing partially an over-deformation region.SOLUTION: In a stent including such a self-extension area 56 that skeletons 52, 54 are deformed into a shape set beforehand by super elasticity, a part deviated to the axial direction from the self-extension area 56 in the skeletons 52, 54 is used as an over-deformation region 58 deformable larger than the self-extension area 56, and thereby a deformed shape can be set with a larger degree of freedom.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a stent that is inserted and placed in a body lumen such as a blood vessel.

  Conventionally, when an abnormality such as stenosis or occlusion occurs in a lumen such as a blood vessel, for example, a stent treatment is performed in which a stent is inserted into the lumen and the lumen is held in an expanded state. As described in, for example, Japanese Patent Application Laid-Open No. 2007-267844 (Patent Document 1) and the like, the stent has a cylindrical shape as a whole, and has a small diameter when inserted into the lumen. The diameter is expanded in place.

  By the way, there are various types of stents such as prevention of restenosis of the body lumen, ease of positioning to the stenosis site in the body lumen, and allow deformation according to the curvature or branching of the indwelling site in the body lumen. Performance is required. Therefore, a biodegradable stent that can be decomposed and absorbed by living tissue has been developed as a stent that can suppress the occurrence of restenosis, and self-expanding that is easy to position to a predetermined position by self-expandability due to superelasticity etc. Stents are also being developed.

  However, in various types of stents having a conventional structure, the required characteristics may not be sufficiently achieved, and further improvements in the performance of these stents are required.

JP 2007-267844 A

  The present invention has been made in the background of the above-mentioned circumstances, and the invention according to claims 1 to 6 provides a stent having a novel structure in which the shape after deformation can be set with a greater degree of freedom. The purpose is to provide.

  It is an object of the invention according to the parent application to provide a stent having a novel structure capable of adjusting the degradation rate by a living body with a greater degree of freedom.

  A first aspect of the present invention is a stent including a cylindrical skeleton that can be expanded and contracted in a radial direction, the skeleton including a self-expanding region that is deformed into a predetermined shape by superelasticity, and the skeleton A portion of the self-expanding region that is off in the axial direction is an over-deformation region that can be deformed larger than the self-expanding region.

  In the stent structured according to this aspect, in the self-expanding region, rapid expansion to a preset shape based on superelasticity can be realized, and excellent shape retention characteristics after expansion can be obtained. On the other hand, the over-deformation region can be appropriately deformed according to the shape of the indwelling site by mechanical expansion using a balloon or a mechanical device, and is particularly allowed to be deformed larger than the self-expansion region. , The degree of freedom in setting the shape is great. The stent skeleton is composed of such self-expanding regions and over-deformed regions having mutually different characteristics, which greatly increases the degree of freedom of shape when the stent is placed and the shape stability when it is placed. Can be set with degrees of freedom.

  A second aspect of the present invention is the stent according to the first aspect of the present invention, wherein at least one end of the skeleton in the axial direction is the over-deformed region.

  In the stent having the structure according to this aspect, the axial end of the skeleton is pressed against the lumen wall by, for example, expanding and deforming the hyperdeformed region so as to have a larger diameter than the self-expanding region. The position and the indwelling posture are stably maintained, and the flow of blood and the like is prevented from stagnation due to the gap between the axial end of the stent and the lumen wall, and thrombus generation is suppressed.

  According to a third aspect of the present invention, there is provided a stent according to the first or second aspect of the present invention, wherein the overdeformed region is capable of expanding and deforming to a larger diameter than the self-expanding region. is there.

  In the stent having the structure according to this aspect, the hyperdeformation region can be expanded and deformed to have a larger diameter than the self-expansion region. The diameter of the stenosis portion can be increased. Furthermore, even when the stenosis of the lumen is not sufficiently expanded by the superelasticity of the self-expanding region due to calcified lesions or arteriosclerosis, the hyperdeformation region can be expanded to a larger diameter than the self-expanding region. By this, it may be possible to push the stenosis site with a greater force.

  A fourth aspect of the present invention is the stent according to any one of the first to third aspects of the present invention, wherein the overdeformed region is expanded by a balloon and can be deformed more than the self-expanded region. It is what is said.

  In the stent having the structure according to this aspect, the hyperdeformed region can be easily deformed into a shape corresponding to the lumen shape by expanding the balloon, and the stenotic site can be adjusted by adjusting the internal pressure of the balloon. It is possible to accurately apply an appropriate force to.

  Moreover, according to the balloon expansion, the over-deformed region is not only greatly deformed in the radial direction with respect to the self-expanded region, but also the stent is bent or curved by largely deforming in the axial direction. It is also possible to deform with a large degree of freedom in accordance with the shape, and for example, deformation as in the following fifth aspect can be realized.

  A fifth aspect of the present invention is the stent according to the fourth aspect of the present invention, wherein the gap in the peripheral wall portion of the over-deformation region is expanded by the balloon and deformed to be larger than the gap in the self-expansion region. It is possible.

  A stent having a structure according to this embodiment is used when a stent is placed at a branching site of a lumen by pushing a gap between struts in an over-deformed region having a plurality of annular shapes, mesh shapes, spiral shapes, or the like with a balloon. Can also be suitably employed. Note that it is also possible to insert another stent into the branch lumen through the gap in the hyperdeformed region pushed and expanded by the balloon.

  A sixth aspect of the present invention is the stent according to any one of the first to fifth aspects of the present invention, wherein the self-expanding region and the over-deformed region are formed by spraying, vapor deposition, etching, electroforming, It is formed by at least one of these.

  In the stent structured according to this aspect, a stent having a structure including a self-expanding region and an overdeformed region can be easily manufactured with a good yield.

  The first aspect of the invention according to the parent application is a stent having a cylindrical skeleton that can be expanded and contracted in the radial direction, wherein the skeleton is formed of a biodegradable metal and a biodegradable metal layer. In addition, the surface of the core layer in the skeleton is biodegraded on both the inner peripheral surface and the outer peripheral surface of the core layer. The biodegradable synthetic resin is formed from the inner peripheral surface and the outer peripheral surface of the skeleton toward the center in the thickness direction by laminating the core decomposition control layer formed of the synthetic resin. And a plurality of the biodegradable metals.

  In the stent having the structure according to this aspect, the time required for biodegradation of the stent can be set with a large degree of freedom by adjusting the biodegradation rate of the core layer of the skeleton by the laminated core decomposition control layer. Therefore, it is possible to secure a sufficient expansion support period for the stenosis site by the placed stent, and risks such as inflammation of the body lumen and associated restenosis due to the stent being placed over a long period of time. Can also be reduced.

  In addition, by appropriately selecting each forming material of the core layer and the core degradation control layer, it is possible to reduce the influence of the product of the biodegradation reaction of the core layer and the core degradation control layer on the living tissue such as the blood vessel wall. it can. Specifically, when the core layer and the core decomposition control layer are composed of a combination of magnesium and poly-L-lactic acid, water ions generated when magnesium is decomposed are water generated during biodegradation of poly-L-lactic acid. Neutralization with oxide ions reduces the influence of hydrogen ions on living tissues.

  Furthermore, in the stent having the structure according to the present aspect, the core degradation control layer covers both surfaces of the core layer, so that the biodegradation of the core layer can be controlled more effectively. In addition, since both surfaces of the core layer are protected by the core decomposition control layer, damage and deterioration of the core layer can be suppressed. Furthermore, in the stent having the structure according to this embodiment, the skeleton characteristics can be adjusted with a greater degree of freedom by making the core layer a multilayer structure. Specifically, for example, if the core layer has a multilayer structure in which a plurality of biodegradable metal layers and biodegradable resin layers are alternately laminated, the biodegradation rate can be adjusted with higher accuracy, It may be possible to provide flexibility and easily cope with bending or bending of the body lumen. In addition, for example, if a core layer in which a plurality of types of biodegradable resin layers with different biodegradation rates, hardnesses, and supported drugs are laminated is used, the complex required for a stent depending on the lesion It is also possible to realize the characteristics as appropriate.

  A second aspect of the invention according to the parent application is a stent according to the first aspect of the invention according to the parent application, wherein the skeleton has a contrast layer formed of a radiopaque material. is there.

  The stent according to this aspect has a contrast layer that exhibits high visibility under X-ray fluoroscopy, so that the position of the stent can be easily confirmed in stent placement under X-ray fluoroscopy.

  In addition, if the contrast layer is made of a stable material that is difficult to biodegrade, such as gold or platinum, even if the skeleton of the stent is biodegraded and disappears, the contrast layer remains in the body. By this, it is possible to confirm the trace where the stent is placed. In addition, since the contrast layer is not required to have a strength capable of maintaining the structure against an external force like a skeleton of a stent, it can be a thin film, and the contrast layer can be formed of a material that is not biodegradable. The effect on living tissue is extremely small. In particular, by selecting a material having excellent biocompatibility such as gold or platinum, residual in vivo is not a problem.

  A third aspect of the invention according to the parent application is a stent according to the first or second aspect of the invention according to the parent application, wherein the core layer and the core decomposition control layer are sprayed, vapor deposited, etched, and electroformed. And at least one of them.

  With a stent having a structure according to this aspect, a stent having a laminated structure including a core layer and a core degradation control layer can be easily manufactured with a good yield.

  In the first to sixth aspects of the present invention, the skeleton of the stent is composed of a self-expanding region that automatically expands by superelasticity, and an overdeformed region that is mechanically deformed by a balloon or the like. The overdeformation region can be deformed larger than the self-expansion region. Therefore, the self-expanding region realizes rapid deformation to the initial shape and maintenance of the stenotic region in the expanded state due to the shape stability after deformation, while the hyperdeformation region allows the shape of the lumen to be maintained. It is possible to deform with a large degree of freedom according to the above, and to cope with various indwelling sites.

  In addition, according to the 1st-3rd aspect of the invention which concerns on a parent application, the core decomposition | disassembly control layer by which the frame | skeleton of the stent was formed with the biodegradable material on the surface of the core layer formed with the biodegradable material Since the biodegradation rate of the core layer can be adjusted by the core decomposition control layer, the indwelling period of the stent in the body can be set with high flexibility and high accuracy.

The front view which shows the stent as 1st Embodiment of the invention which concerns on a parent application. The cross-sectional enlarged view of the strut which comprises the frame | skeleton of the stent shown in FIG. The cross-sectional enlarged view of the strut which comprises the frame | skeleton of the stent as 2nd Embodiment of the invention which concerns on a parent application. The cross-sectional enlarged view of the strut which comprises the frame | skeleton of the stent as 3rd Embodiment of the invention which concerns on a parent application. The cross-sectional enlarged view of the strut which comprises the frame | skeleton of the stent as 4th Embodiment of the invention which concerns on a parent application. It is a front view which shows the stent as the 1st Embodiment of this invention, Comprising: (a) shows a catheter accommodation state, (b) shows an indwelling state. It is a front view which shows the stent as the 2nd Embodiment of this invention, Comprising: (a) shows a catheter accommodation state, (b) shows an indwelling state. It is a front view which shows the stent as the 3rd Embodiment of this invention, Comprising: (a) shows a catheter accommodation state, (b) shows the state which only the overdeformed area | region expanded, (c) shows an indwelling state. . The front view which shows the stent as the 4th Embodiment of this invention. The front enlarged view which shows the structural example of the chemical | medical agent accommodation recess employable as another aspect of this invention. The cross-sectional enlarged view which shows the structural example of the ultrasonic marker which can be grasped | ascertained also as invention different from this invention. The front view of a cover stent provided with the ultrasonic marker shown in FIG. The perspective view of the stent retriever comprised with the ultrasonic marker shown in FIG. The front view of a catheter provided with the ultrasonic marker shown in FIG. The perspective view of the coil comprised by the ultrasonic marker shown in FIG. The front view which shows the whole shape of the stent as 1 aspect which can be grasped | ascertained as invention different from this invention. The front view which shows the whole shape of the stent as another aspect which can be grasped | ascertained as invention different from this invention. The front view which shows the whole shape of the stent as another aspect which can be grasped | ascertained as invention different from this invention. It is sectional drawing which shows the specific example of the frame | skeleton employable in the stent of FIGS. 16-18, Comprising: The figure which shows a substantially triangular shape (a) and a substantially inverted triangular shape (b). Explanatory drawing which shows roughly the position of the weak part employable in the stent of FIGS. Explanatory drawing which shows schematically the position of a suitable weak part in the stent of FIGS. The front view which shows the whole shape in the molding state of the stent as another aspect which can be grasped | ascertained as invention different from this invention. (A) is a perspective view which expands and shows the cross section of the axis orthogonal direction in the stent shown by FIG. 22, (b) is a principal part enlarged view in the axial direction view of (a). Explanatory drawing for demonstrating the magnitude | size of the center angle of the outer peripheral surface and the depression angle of the circumferential direction both sides in sectional drawing of the skeleton shown by FIG.19 (b). Explanatory drawing for demonstrating the principal part of the diameter-reduced state of the stent shown by FIG. (A) is an axial view in the diameter-reduced state of the stent shown by FIG. 25, (b) is explanatory drawing which expands and shows the principal part of (a). The front view which shows the whole shape of the stent as still another aspect which can be grasped | ascertained as invention different from this invention. The front view which shows the whole shape of the stent as another aspect which can be grasped | ascertained as invention different from this invention. It is explanatory drawing which shows the Example of the stent which can be grasped | ascertained as invention different from this invention, Comprising: The figure corresponding to FIG. It is explanatory drawing which shows the comparative example of the stent which can be grasped | ascertained as invention different from this invention, Comprising: The figure corresponding to FIG. It is explanatory drawing for demonstrating the principal part of the diameter-reduced state of the stent shown by FIG. 29, Comprising: The figure corresponding to FIG. FIG. 27 is an explanatory diagram for explaining a main part in a reduced diameter state of the stent shown in FIG. 31 and corresponding to FIG. 26. It is explanatory drawing for demonstrating the principal part of the diameter-reduced state of the stent shown by FIG. 30, Comprising: The figure corresponding to FIG. It is explanatory drawing for demonstrating the principal part of the diameter-reduced state of the stent shown by FIG. 33, Comprising: The figure corresponding to FIG. FIG. 23 is an explanatory diagram for explaining the result of confirming the flow velocity using the stent shown in FIG. 22 which is an embodiment of a stent that can be grasped as an invention different from the present invention, and FIG. The velocity distribution near the wall surface is shown by a vector, and (b) shows the velocity distribution near the blood vessel wall surface by a plane. FIG. 36 is an explanatory view for explaining the result of confirming the flow velocity using the stent shown in FIG. 29 which is another embodiment of the stent which can be grasped as another invention different from the present invention, and corresponds to FIG. To do. It is explanatory drawing for demonstrating the result of having confirmed the flow velocity using the stent shown in FIG. 30 which is a comparative example of the stent which can be grasped as another invention different from the present invention, and corresponds to FIG. Figure.

  Hereinafter, the invention according to the parent application and embodiments of the present invention will be described with reference to the drawings.

  First, FIG. 1 shows a stent 10 as a first embodiment of the invention according to the parent application in a molded state before being contracted or expanded. The stent 10 is delivered to a stenotic site of a body lumen such as a blood vessel and is placed in an expanded state at the stenotic site, so that the body lumen is maintained in an expanded state. In the following description, the axial direction refers to the vertical direction in FIG.

  More specifically, the stent 10 of the present embodiment is linearly extended in a generally cylindrical shape as a whole, and includes a plurality of annular portions 12 provided at a predetermined distance in the axial direction. . The annular portion 12 is formed to continuously extend in the circumferential direction by repeatedly curving or bending in a wave shape.

  The annular portions 12 and 12 that are adjacent in the axial direction are connected to each other by a link portion 14 that extends substantially in the axial direction, thereby forming a tubular stent 10 having a predetermined length. In the present embodiment, each annular portion 12 and each link portion 14 are integrally connected to constitute a strut 16 as a skeleton. The cylindrical strut 16 can be expanded and contracted in the radial direction of the stent 10. In the present embodiment, each annular portion 12 is folded at both ends in the axial direction, and the folded portions of the annular portions 12, 12 facing each other in the axial direction are connected by the link portion 14. As a result, the strength and the degree of freedom of deformation of the stent 10 are improved, and local deformation such as buckling of the struts 16 during deformation is prevented.

  The specific shapes of the annular portion 12 and the link portion 14 are not limited in the invention according to the parent application, and the wave shape of the annular portion 12 and the link portion are considered in consideration of the characteristics required for the stent 10. 14, the number of link portions 14 on the circumference of the annular portion 12, and the like can be appropriately set.

  Further, the position of the link portion 14 provided between the annular portions 12 and 12 is not limited in any way, but the link portion 14 is formed in the central portion of the annular portion 12 in the thickness direction (vertical direction in FIG. 2). It is desirable. Furthermore, the link part 14 in this embodiment is located in the center part of the width direction (circumferential direction of the stent 10) of the folded part in the annular part 12, that is, the top part of the folded part in the annular part 12.

  Here, the link part 14 can also be made into the weak part which made thickness dimension or width dimension smaller than the cyclic | annular part 12. FIG. That is, in the skeleton of the stent 10, the cross-sectional area of the link portion 14 can be made smaller than that of the annular portion 12, so that it can be formed as a weakened portion having a partially reduced strength. Then, by forming the fragile portion, the stent 10 may be easily deformed or broken at the fragile portion.

  In addition, although the width dimension and thickness dimension of the annular part 12 and the link part 14 are not particularly limited, the annular part 12 has a width dimension and a thickness dimension of about 30 to 200 μm for the purpose of ensuring strength. It is desirable that the link part 14 has a width dimension and a thickness dimension of about 10 to 100 μm.

  The strut 16 has a laminated structure as shown in FIG. That is, in the strut 16 of the present embodiment, the core decomposition control layer 20a is laminated on the inner peripheral surface (the lower surface in FIG. 2) of the core layer 18, and the outer peripheral surface (the upper surface in FIG. 2) of the core layer 18. The core decomposition control layer 20b is laminated.

  The core layer 18 is formed of a biodegradable material that is decomposed and absorbed in a predetermined period by a living tissue constituting a body lumen. In the present embodiment, the core layer 18 is formed of a biodegradable resin. The biodegradable resin material forming the core layer 18 is not particularly limited as long as it is a biodegradable material that is decomposed and absorbed by a living body and is a biocompatible material that has a small influence on the living body when placed in the body. However, for example, poly-L-lactic acid (PLLA), polycaprolactone, polyglycolic acid, copolymers or composites thereof are suitably employed, and PLLA is employed in this embodiment.

  The core decomposition control layer 20 is formed of a biodegradable material, and is formed of a biodegradable metal in this embodiment. The biodegradable metal material forming the core decomposition control layer 20 is not particularly limited as long as it has both biodegradability and biocompatibility. For example, Mg, Ca, Zn, Li, Fe, or their main components are used. An alloy or the like is preferably employed, and an Mg alloy is employed in the present embodiment. In addition, the Mg alloy which is a material for forming the core decomposition control layer 20 is obtained by adding the above-described biodegradable metal elements (except for Mg) and other biocompatible metal elements to the main component Mg. Has been. In the present embodiment, the core decomposition control layer 20a and the core decomposition control layer 20b are formed of the same material, but the materials for forming the core decomposition control layers 20a and 20b may be different from each other.

  The core decomposition control layer 20 a is stacked on the inner peripheral surface of the core layer 18, and the core decomposition control layer 20 b is stacked on the outer peripheral surface of the core layer 18. In the present embodiment, as shown in FIG. 2, core decomposition control layers 20a and 20b are laminated so as to cover substantially the entire surfaces of the core layer 18. The core decomposition control layers 20a and 20b are preferably porous structures having a large number of fine voids penetrating in the thickness direction, whereby the surface of the core layer 18 is microscopically. It is desirable that the core decomposition control layers 20a and 20b are exposed to the outside through gaps.

  The stent 10 having the struts 16 having such a laminated structure is manufactured by integrally forming a plurality of annular portions 12 and link portions 14 each formed of the struts 16 by thermal spraying.

  Specifically, the sprayed particles of the material that has been melted or brought close to it by heating are sprayed onto a base material that has been masked corresponding to the peripheral wall structure of the stent 10, so that a large number of the sprayed particles have a predetermined shape. The stent 10 can be formed by solidifying.

  In this embodiment, the entire skeleton of the stent 10 is integrally formed, and the laminated structure shown in FIG. 2 is applied not only to the annular portion 12 but also to the link portion 14. However, the laminated structure of the core layer 18 and the core decomposition control layers 20a and 20b as shown in FIG. 2 does not have to be applied to the entire skeleton. For example, several annular portions 12 have such a laminated structure and other structures. The annular portion 12 may have a single layer structure made of one kind of biodegradable material, or the link portion 14 may have a single layer structure.

  Moreover, since the stent 10 of this embodiment is a laminated structure, it is produced through the following processes, for example. That is, first, sprayed particles of Mg alloy are sprayed on the base material, and the inner core decomposition control layer 20a is spray-formed, and then sprayed particles of PLLA are sprayed on the surface of the core decomposition control layer 20a. 18 is formed by thermal spray molding. Finally, sprayed particles of Mg alloy are sprayed on the surface of the core layer 18 to form the outer core decomposition control layer 20b, whereby the stent 10 in which the core decomposition control layers 20a and 20b are laminated on both surfaces of the core layer 18. Is formed.

  In addition to electric spraying such as plasma spraying and arc spraying, spray forming by various known methods such as flame spraying, high-speed flame spraying, and explosion spraying can be employed. Furthermore, cold spray molding is also possible, in which the thermal spray material is plastically deformed into a film or a layer by colliding the thermal spray material with a solid layer at a high speed without being melted or close to the state by heating. Depending on the forming material (spraying material) of the core layer 18 and the core decomposition control layers 20a and 20b to be formed, it can be adopted as one of the spray forming methods of the stent 10.

  The stent 10 of the present embodiment having the above-described structure can be expanded and contracted in the radial direction, and is mechanically reduced in diameter from a state before contraction shown in FIG. 1 to a predetermined size. In use, the diameter-reduced stent 10 is delivered to, for example, a stenosis site of a blood vessel by a delivery catheter or the like. Thereafter, the stent 10 is mechanically expanded by a balloon catheter or other mechanical device, or when the stent 10 is formed of a shape memory material, it is automatically expanded by releasing it from the delivery catheter. In the state shown in FIG. 1, it is placed in a body lumen such as a blood vessel.

  Further, when the stent 10 according to the invention according to the parent application is inserted into a lumen such as a blood vessel, the stent 10 is deformed from the initial shape and is delivered by a catheter. In the case where the stent 10 is a balloon expandable type, the balloon 10 is expanded using the balloon so that the stent 10 is placed in a state of being pressed against the inner peripheral surface of the blood vessel. It is automatically expanded when released. It is also possible to have an almost initial shape in such an expanded state. In this case, the shape in the expanded state is stably expressed, and strain and residual stress in the expanded indwelling state are also generated. Effectively suppressed. However, the invention according to the parent application is not limited to such an embodiment, and can be formed with an initial shape having a diameter different from the shape at the time of placement.

  In such an indwelling state in the body lumen, the stent 10 formed of the biodegradable material keeps the narrowed portion of the body lumen in the expanded state for a necessary period, and a predetermined period has elapsed. After that, by being decomposed and absorbed by body tissues such as blood vessel walls, the indwelling in the body is eliminated.

  Here, in the stent 10, the surface of the core layer 18 is covered with the core decomposition control layers 20a and 20b, and the time required for the decomposition absorption of the core layer 18 is controlled by the core decomposition control layers 20a and 20b. As a result, it is possible to prevent the stent 10 from being decomposed and absorbed too early and the retention period in the expanded state of the body lumen by the stent 10 from being too short, and the decomposition and absorption of the stent 10 to be too late. The risk of causing inflammation and the like can be reduced. Therefore, it is possible to effectively treat a stenosis or occlusion of a blood vessel by stent placement, and it is possible to perform a less invasive stent placement in which restenosis is less likely to occur by accurately controlling the stent placement period.

  In the present embodiment, the core decomposition control layers 20a and 20b are made of an Mg alloy, and the biodegradation speed of the core decomposition control layers 20a and 20b is made slower than the core layer 18 formed of PLLA. Therefore, the core decomposition control layers 20a and 20b covering the surface of the core layer 18 act so as to suppress the decomposition of the core layer 18 in the body for a relatively long period of time, so that the stent 10 is set for a predetermined period. It is easy to adjust the period required for the decomposition so that it is left without being decomposed.

  Furthermore, hydrogen ions generated during biodegradation of the core decomposition control layers 20a and 20b formed of Mg alloy are combined with hydroxide ions generated during biodegradation of the core layer 18 formed of PLLA to generate water. This prevents hydrogen ions generated during the decomposition of the core decomposition control layers 20a and 20b from adversely affecting the body tissue, thereby realizing a less invasive stent placement.

  The thickness dimensions of the core layer 18 and the core decomposition control layers 20a and 20b and the roughness of the porous core decomposition control layers 20a and 20b are determined according to a predetermined period required for biodegradation of the stent 10. In consideration of the above, it is desirable that the neutralization reaction at the time of biodegradation of the core layer 18 and the core decomposition control layers 20a and 20b is appropriately set. This is because if only one of the core layer 18 and the core decomposition control layers 20a and 20b is decomposed first, the remaining biodegradation reaction may affect the body tissue. As is clear from the above, it is desirable that the combination of the forming materials of the core layer 18 and the core decomposition control layers 20a and 20b is selected so that the influence of the biodegradation reaction on the body tissue is reduced.

  Furthermore, since the core decomposition control layers 20a and 20b are made porous, the core layer 18 covered with the core decomposition control layers 20a and 20b is biodegraded at a certain rate by the body tissue. It has become. Thereby, prior to the core layer 18, only the core decomposition control layers 20a and 20b are hardly biodegraded.

  As described above, in the stent 10 according to the invention according to the parent application, the core layer 18 and the core degradation control layers 20a and 20b, each of which is made of a biodegradable material, are laminated to form a multilayer structure. It is possible to achieve both high resolution and avoidance of restenosis. However, in the invention according to the parent application, the material for forming the core layer and the core decomposition control layer and the specific structure of the core layer and the core decomposition control layer are limited to those of the first embodiment. It is not a thing.

  That is, FIG. 3 shows a cross section of a strut 22 constituting a stent as a second embodiment of the invention according to the parent application. This strut 22 has the same laminated structure as the strut 16 of the first embodiment of the invention related to the parent application, and the core decomposition control layer 26a is laminated on the inner peripheral surface of the core layer 24. The core disassembly control layer 26b is laminated on the outer peripheral surface. Also in the present embodiment, both the inner peripheral surface and the outer peripheral surface of the core layer 24 are covered with the core decomposition control layer 26. Further, in the strut 22 of the present embodiment, unlike the strut 16 of the first embodiment of the invention related to the parent application, the core layer 24 is formed of an Mg alloy, and the core decomposition control layers 26a and 26b are PLLA. It is formed with.

  Thus, the core layer 24 may be formed of a biodegradable metal, and the core decomposition control layers 26a and 26b may be formed of a biodegradable resin. According to this, the core layer 24 which is the main part of the stent is formed of a metal material, so that the stent after placement is more firmly maintained in an expanded shape, and the stenotic site of the body lumen is pushed and expanded. Can be kept stable.

  Further, for example, when a drug is supported on a biodegradable resin to have a function as a drug-eluting stent, the core decomposition control layers 26a and 26b, which are outer layers, are formed by a polymer supporting the drug. It is also possible to efficiently release thrombus and prevent inflammation of the blood vessel wall. In order to prevent only the core decomposition control layers 26a and 26b from being decomposed at an early stage, for example, the ratio of the thickness dimension of the core decomposition control layers 26a and 26b to the core layer 24 is determined according to the invention of the parent application. It is desirable to make it larger than one embodiment.

  FIG. 4 shows a cross-section of a strut 28 constituting a stent as a third embodiment of the invention according to the parent application. In the strut 28 of the present embodiment, the core layer 30 has a multilayer structure.

  That is, the core layer 30 has an inner peripheral metal layer 34a stacked on the inner peripheral surface of the central resin layer 32, an outer peripheral metal layer 34b stacked on the outer peripheral surface, and the inner periphery of the inner peripheral metal layer 34a. The inner peripheral resin layer 36a is laminated on the surface, and the outer peripheral resin layer 36b is laminated on the outer peripheral surface of the outer peripheral metal layer 34b. In other words, the core layer 30 of the present embodiment is a multilayer structure in which three resin layers formed of PLLA and two metal layers formed of Mg alloy are alternately stacked. Yes. In addition, the number of layers and the forming material of the core layer 30 having a multilayer structure are merely examples, and are not particularly limited.

  In addition, core decomposition control layers 20a and 20b formed of a biodegradable material are laminated on both surfaces of the core layer 30 as in the first embodiment of the invention according to the parent application. 20a is fixed to the inner peripheral surface of the inner peripheral resin layer 36a, and the core decomposition control layer 20b is fixed to the outer peripheral surface of the outer peripheral resin layer 36b. In short, the strut 28 of the present embodiment has a seven-layer structure in which one core decomposition control layer 20a, 20b is fixed to both surfaces of a five-layer core layer 30, and is formed of an Mg alloy. Metal layers and resin layers formed of PLLA are alternately stacked.

  In this embodiment, all the resin layers 32, 36a, and 36b are formed of PLLA, and all the metal layers 20a, 20b, 34a, and 34b are formed of Mg alloy. Different resin materials may be used, and each metal layer may be formed of different metal materials.

  According to the stent having the core layer 30 having such a multilayer structure, since the core layer 30 has a multilayer structure having a metal layer, the entire core layer, which is the main portion of the stent, is formed of resin. Compared to the case, the stability of the shape is excellent, and recoil is easily suppressed.

  In addition, when a relatively thin metal layer is provided dispersed in the core layer 30 and the core decomposition control layers 20a and 20b, both surfaces of the strut 28 are covered with thick metal core decomposition control layers 20a and 20b. In comparison, excessive suppression of biodegradation of the core layer 30 can also be avoided. In addition, since both surfaces of the strut 28 are covered with the metal core decomposition control layers 20a and 20b, it is easy to prevent the biodegradation rate of the core layer 30 from becoming too fast.

  Thus, according to the stent of this embodiment provided with the struts 28, the biodegradation rate is easily controlled in the stent 10 of the first embodiment of the parent application, and the second aspect of the invention of the parent application. The excellent shape stability in the indwelling state of the stent according to the embodiment can be realized at the same time.

  Moreover, you may provide the contrast layer 40 further with respect to the strut 28 of 3rd Embodiment of the invention based on a parent application like the strut 38 shown in FIG.

  That is, FIG. 5 shows a cross section of a strut 38 constituting a stent as a fourth embodiment of the invention according to the parent application. The core disassembly control layers 20a and 20b and inner metal are formed of metal. The contrast layer 40 is laminated on both surfaces of the layer 34a and the outer peripheral metal layer 34b. The contrast layer 40 is formed of a biocompatible radiopaque material, and a thin film such as Au, Pt, or tantalum can be suitably used. In the present embodiment, the core layer 30 is configured to include four contrast layers 40, 40, 40, 40 laminated on both surfaces of the inner metal layer 34a and both surfaces of the outer metal layer 34b. In addition to the core decomposition control layers 20a and 20b, the core decomposition control layer includes four contrast layers 40, 40, 40, and 40 stacked on both surfaces thereof. The inner and outer core disassembly control layers also have a multilayer structure.

  The contrast layer 40 does not necessarily cover the entire surfaces of the core decomposition control layers 20a and 20b and the metal layers 34a and 34b, and may be partially laminated. Further, in this embodiment, the contrast layer 40 is laminated on both surfaces of the core decomposition control layers 20a and 20b and the metal layers 34a and 34b, but the core decomposition control layers 20a and 20b and the metal layers 34a and 34b are stacked. It may be selectively laminated on only one or several, or may be laminated only on one of the surfaces of the core decomposition control layers 20a and 20b and the metal layers 34a and 34b.

  Providing such a contrast layer 40 makes it easy to confirm the position of the stent in stent placement under fluoroscopy. In addition, since the contrast layer 40 is formed into a plurality of thin layers arranged apart from each other, particularly excellent visibility is exhibited in the overlapping portion of the contrast layers 40 under X-ray fluoroscopy.

  Further, if the contrast layer 40 is formed of a material that does not have biodegradability such as Au or Pt, the decomposition rate of each of the core layer 30 and the core decomposition control layers 20a and 20b formed of the biodegradable material is It can also be adjusted by the contrast layer 40. Furthermore, since the contrast layer 40 remains in the body tissue even after all the portions of the stent formed of the biodegradable material are decomposed and absorbed, the contrast layer 40 remaining in the body tissue can be confirmed by fluoroscopy. For example, it is possible to grasp the site where the stent is placed in the blood vessel even after the stent body is decomposed and absorbed. The contrast layer 40 has excellent biocompatibility and is formed of Au or Pt, which is a stable material, and is sufficiently thin, so restenosis or the like does not pose a problem.

  By the way, when the stent is placed at the stenosis site in the body lumen as described above, it is desirable that the stent shape after placement is highly compatible with the shape of the stenosis site in the body lumen. Accordingly, FIGS. 6 to 9 show other embodiments of stents 50, 60, 62, and 68 in which the shape after placement can be highly adapted to the shape of the stenosis site in the body lumen. Has been.

  That is, FIG. 6 shows a stent 50 as a first embodiment of the present invention. The stent 50 has a cylindrical shape extending substantially linearly before placement, and a plurality of annular portions 52 are arranged in the axial direction in the same manner as the stent 10 according to the first embodiment of the parent application. In addition, the annular skeletons 52 and 52 that are adjacent in the axial direction are connected by the link portion 54, thereby forming a cylindrical skeleton. In addition, in the following description, about the member and site | part substantially the same as 1st-4th embodiment of the invention which concerns on a parent application, description is abbreviate | omitted by attaching | subjecting the same code | symbol in a figure. In FIG. 6, (a) shows the stent 50 housed in the delivery catheter in a reduced diameter state, and (b) shows the stent 50 placed in the body lumen.

  The stent 50 also has a plurality of self-expanding regions 56 and a plurality of overdeformed regions 58. In the present embodiment, five self-expanding regions 56 arranged in the axial direction are provided, and overdeformation regions 58 are provided between the self-expanding regions 56 in the axial direction.

  The self-expanding region 56 is formed of a metal material having a shape memory effect, and is released from a delivery catheter accommodated in a reduced diameter state, so that the self-expanding region 56 is automatically shaped in advance by superelasticity (during molding). The shape is restored and expanded. Each self-expanding region 56 includes two annular portions 52a and 52a that are adjacent in the axial direction, and a plurality of link portions 54a that connect them, and the annular portions 52a and 52a and a plurality of links. The portion 54a is integrally formed of a shape memory material. The material for forming the self-expanding region 56 is not particularly limited as long as it is a biocompatible superelastic material. For example, various alloys such as a NiTi alloy are preferably used.

  The over-deformation region 58 is provided in a portion that is off the self-expanding region 56 in the axial direction, is formed of a metal material that does not have a shape memory effect, and is released from a delivery catheter accommodated in a reduced diameter state. After that, it can be mechanically expanded by a balloon or the like. Further, the excessive deformation region 58 can be deformed to be larger than the self-expanding region 56 by adjusting the force exerted by the balloon or the like. It can be extended in the axial direction larger than the expansion region 56.

  The material for forming the over-deformed region 58 is not particularly limited as long as it is a biocompatible material and can be easily deformed by a balloon or the like. For example, stainless steel (SUS316L), CrCo alloy, tantalum Etc. can be suitably employed. Each over-deformed region 58 includes two annular portions 52b and 52b adjacent in the axial direction and a link portion 54b that connects them, and the annular portions 52b and 52b and the link portion 54b are described above. It is formed with the following materials. The annular portion 52a and the annular portion 52b have substantially the same shape in the molded state and have different forming materials, and the annular portion 52 includes two types of annular portions 52a and 52b that are different in forming material. Has been. Similarly, the link portion 54a and the link portion 54b are also formed of different forming materials having substantially the same shape, and the link portion 54 is composed of two types of link portions 54a and link portions 54b having different forming materials.

  Further, the self-expanding region 56 and the hyperdeformed region 58 may be covered with a thin layer such as radiopaque Au, Pt, or Ta so that the visibility of the stent 50 can be seen under fluoroscopy. Is improved. In addition, since the stent 50 of the present embodiment expands into a bent shape so as to correspond to the bent blood vessel, the bending direction in the expanded state of the stent 50 can be grasped under fluoroscopy. For example, it is desirable to provide an X-ray marker indicating the bent inner peripheral side.

  And the stent 50 is formed by the self-expanding area | region 56 and the overdeformation area | region 58 being continuously provided alternately by the axial direction. That is, both end portions in the axial direction of the stent 50 are self-expanding regions 56, and overdeformation regions 58, 58, 58, 58 and self-expanding regions 56 are formed inside the self-expanding regions 56, 56 constituting the both end portions. , 56, 56 are alternately arranged. The self-expanding region 56 and the overdeformed region 58 of this embodiment are integrally formed by means such as spraying, vacuum deposition, etching, electroforming, etc., but are fixed to each other by welding after being formed separately. May be.

  The stent 50 having such a structure is accommodated in a delivery catheter in a reduced diameter state shown in FIG. 6A, and is carried to a stenotic site of a body lumen by the delivery catheter, and then from the delivery catheter. It is released and placed at the stenosis site in the body lumen.

  In addition, the stent 50 of the present embodiment is applied when the stenosis portion of the body lumen is curved or bent, and as shown in FIG. 6B, the bent or bent corresponding to the body lumen. Detained in shape. That is, when the stent 50 is placed in a curved or bent stenosis site, the self-expanding region 56 is automatically expanded by superelasticity and pressed against the inner wall of the body lumen, and the The deformation or bending of the stent 50 is adjusted according to the shape of the body lumen. Further, the hyperdeformed region 58 is allowed to deform larger than the self-expanding region 56 and can be shaped by a balloon or the like after releasing the stent 50 from the delivery catheter. Therefore, by appropriately deforming the over-deformed region 58, the shape of the stent 50 can be adjusted after the expansion deformation of the self-expanding region 56 to be more adapted to the shape of the body lumen. FIG. 6B shows an example in which the left part of the over-deformed region 58 in the figure is deformed to be larger than the right part in the figure so that the curved shape is inclined to the right in the figure as it goes to both ends in the axial direction. However, the deformation | transformation aspect of the overdeformation area | region 58 is not limited to this. Note that the stent 50 of the present embodiment that expands into a curved or bent shape is particularly effective for highly curved or bent portions of, for example, a blood vessel of a patient who has advanced arteriosclerosis.

  Further, when the stenosis part of the body lumen is hard enough not to be expanded in the self-expanding region 56, the stenosis part can be expanded by balloon expansion of the over-deformation region 58. When the stenosis part is pushed and expanded by balloon expansion of the over-deformation region 58, if the restriction by the stenosis part is released and the self-expansion area 56 is expanded, the stenosis part is supported by the self-expansion area 56 and stenosis by recoil is performed. Is avoided. The over-deformed region 58 that is covered and formed of SUS is relatively easily deformed by the action of an external force, as is understood from allowing expansion by a balloon, but the self-formed region formed of NiTi alloy. This is because the expansion region 56 exhibits expansion deformation due to transformation from the martensite phase to the parent phase, and exhibits high deformation rigidity after expansion.

  FIG. 7 shows a stent 60 as a second embodiment of the present invention. The stent 60 has a linear cylindrical shape as a whole, and has an intermediate portion as a self-expanding region 56 and both end portions as an overdeformed region 58. In FIG. 7, (a) shows the stent 60 housed in the delivery catheter in a reduced diameter state, and (b) shows the stent 60 in a state of being placed in the body lumen. .

  In the state in which the stent 60 is housed in the delivery catheter, both the self-expanding region 56 and the over-deformed region 58 are reduced in diameter, and as shown in FIG. It has a constant outer diameter.

  Then, the stent 60 carried to the stenosis portion of the body lumen by the delivery catheter is placed in an expanded state as shown in FIG. That is, in the stent 60 released from the delivery catheter, the self-expanding region 56 automatically expands and deforms to expand the wall portion of the stenosis site, and the over-deformation regions 58 at both ends have the expanded self-expanding region. The diameter is expanded and deformed by a balloon so as to have a larger diameter than 56. In FIG. 7 (b), the overdeformed region 58 is deformed into a tapered shape having a diameter that increases outward in the axial direction, and both ends of the overdeformed region 58 are stabilized against the inner wall of the body lumen. To be pressed.

  According to this, since both ends of the stent 60 are easily brought into close contact with the inner wall of the body lumen, thrombus formation due to blood flow disturbance at both ends is reduced or avoided, and restenosis or the like is performed. Can be avoided. In particular, since both ends of the stent 60 are constituted by the hyperdeformed region 58 and can be deformed later by a balloon in accordance with the shape of the body lumen, the stent 60 is securely attached to the blood vessel wall or the like. While being able to indwell in a more stable state, the formation of thrombus can be suppressed.

  FIG. 8 shows a stent 62 as a third embodiment of the present invention. The stent 62 has a structure in which a hyperdeformed region 58 is provided at the distal end (lower end in FIG. 8) of the self-expanding region 56. FIG. 8A shows a state where the stent 62 is accommodated in the delivery catheter 64. (B) shows a state in which the self-expanding region 56 of the stent 62 is accommodated in the delivery catheter 64 and the over-deformed region 58 is released from the delivery catheter 64. (C) shows an indwelling state in which the stent 62 is released from the delivery catheter 64.

  Then, as shown in FIG. 8A, the stent 62 accommodated in the delivery catheter 64 is transported to the stenosis part of the body lumen, and then, as shown in FIG. While housed in the delivery catheter 64, the distal end hyperdeformed region 58 is released from the delivery catheter 64 and is expanded by the balloon catheter 66. As a result, the hyperdeformed region 58 is pressed against the inner wall surface of the body lumen, and the stent 62 is positioned with respect to the body lumen. Note that the delivery catheter 64 and the balloon catheter 66 are not requirements for configuring the present invention, but are shown in FIGS. 8A and 8B for the purpose of facilitating understanding.

  Next, as shown in FIG. 8 (c), the self-expanding region 56 is released from the delivery catheter 64 and is pressed against the constriction portion of the body lumen by self-expansion based on superelasticity. It is expanded by the stent 62.

  In a typical self-expanding stent, when the proximal end of the stent is released from the delivery catheter, a distal-direction force may act on the stent, resulting in a displacement of the indwelling position due to jumping. Here, since the stent 62 of the present embodiment is positioned with respect to the body lumen by the pre-expanded hyperdeformed region 58, jumping can be prevented from occurring when the self-expanding region 56 is released.

  FIG. 9 shows a stent 68 as a fourth embodiment of the present invention. The stent 68 has a self-expanding region 56 at both ends in the axial direction and an over-deformed region 58 at the intermediate portion.

  Then, in the indwelling state in the body lumen shown in FIG. 9, the stent 68 has a tubular skeleton formed by a part of the wall portion of the skeleton constituting the over-deformed region 58 being expanded by a balloon or the like. A branch opening 69 that opens to the side is formed in a part of the wall. More specifically, in the stent 68 of the present embodiment, a balloon is inserted between the axial directions of the adjacent annular portions 52a and 52b, and the gap between the annular portions 52a and 52b is expanded by the balloon. The over-deformed region 58 is deformed larger than the self-expanding region 56 to form a branch opening 69 that penetrates the peripheral wall portion of the skeleton.

  As described above, if the branch opening 69 can be formed in the peripheral wall portion of the skeleton by the deformation of the over-deformed region 58, the stent 68 according to the present invention can be suitably used as a stent to be placed in the branch portion of the blood vessel. In addition, since the branch opening 69 is formed by the post-deformation of the hyperdeformed region 58 by the balloon in a state where the stent 68 is positioned with respect to the body lumen by the deformation of the self-expanding region 56, The shape can be more accurately matched to the branch portion of the blood vessel. It should be noted that another stent can be inserted into the branch vessel through the branch opening 69 after the stent 68 is placed.

  In the present embodiment, an example in which the branch opening 69 is formed between the axial directions of the adjacent annular portions 52a and 52b has been shown. However, for example, the branch opening 69 is formed between the axial directions of the adjacent annular portions 52b and 52b. It can also be formed. Further, the branch opening 69 may be formed by deforming the annular portion 52b so as to expand in the axial direction, or the branch opening 69 can be formed by expanding the annular portion 52b in the circumferential direction.

  As described above, the invention according to the parent application and the embodiments and examples of the present invention have been described in detail. However, the invention according to the parent application and the present invention are not limited by the specific description, and are based on the knowledge of those skilled in the art. The present invention can be carried out in a mode with various changes, modifications, improvements, etc., and any such embodiment can be applied to the parent application without departing from the invention of the parent application and the gist of the present invention. It falls within the scope of the present invention and the present invention.

  For example, in the first to fourth embodiments of the invention according to the parent application, the structure is not limited to the structure in which the core decomposition control layers 20 and 26 are laminated on the entire surface of the core layers 18, 24, and 30. The control layers 20 and 26 may be partially provided on the surface of the core layers 18, 24 and 30. The core decomposition control layers 20 and 26 may be formed only on the surface of any one of the core layers 18, 24 and 30.

  Further, for example, in the stent 10 of the first embodiment of the invention according to the parent application, the core layer 18 is formed of a biodegradable metal, or the core decomposition control layers 20a and 20b are formed of a biodegradable resin. And the whole may be formed with biodegradable resin or a biodegradable metal. The core layer and the core decomposition control layer may be formed of the same material, but are preferably formed of different materials. For example, even when both the core layer and the core decomposition control layer are formed of an Mg alloy, the core layer and the core are made different by changing the kind of metal element added to Mg, which is the main component, and the proportion of the metal element. It is desirable to impart suitable characteristics to the decomposition control layer.

  Furthermore, when the core layer and the core decomposition control layer have a laminated structure like the core layer 30 of the third and fourth embodiments of the invention according to the parent application, The structure is not limited to the structure in which the biodegradable resin layer and the biodegradable metal layer are alternately arranged as in the third and fourth embodiments, and a multi-layered core layer (core decomposition control layer) has a plurality of types of biodegradable layers. It may be formed of a decomposable resin layer or may be composed of a plurality of types of biodegradable metal layers. Note that both the core layer and the core decomposition control layer may have a multilayer structure.

  Further, in the structure of the first and second embodiments of the invention related to the parent application having the core layers 18 and 24 having the single layer structure, the contrast layer 40 as in the fourth embodiment of the invention related to the parent application is provided. May be. The contrast layer 40 may be formed of a single material having excellent contrast properties such as Au and Pt. For example, the contrast material is mixed with the biodegradable material substantially uniformly and sprayed (co-spray). Thus, the core layers 18 and 24 and the core decomposition control layers 20 and 26 can also be formed so as to serve as a contrast layer.

  Further, in the stent including the self-expanding region 56 and the overdeformed region 58 as in the first to fourth embodiments of the present invention, the self-expanding region 56 and the overdeformed region 58 are arranged at mutually different positions in the axial direction. If arranged, their arrangement can be changed as appropriate.

  For example, an appropriate shape such as embossing may be attached to the surface of the stent, and when the stent is produced by thermal spraying, by appropriately setting the shape of the base material or mask used for thermal spraying. An appropriate shape such as embossing can be easily formed on the surface. Thus, by providing unevenness on the outer peripheral surface of the stent, for example, it can be effectively used as a drug-eluting stent. That is, for example, by applying or depositing a drug that suppresses cell growth or a resin layer containing such a drug on the outer peripheral surface of a stent with irregularities, the drug can be eluted from the blood vessel wall. it can. At that time, the wettability is improved by such unevenness, and the applied drug or the resin layer can be easily attached to the outer peripheral surface of the stent and can be made difficult to peel off.

  Further, as shown in FIG. 10, for example, a medicine containing recess 70 for containing medicine may be formed in the skeleton of the stent, that is, the annular portion 12 and the link portion 14. Specifically, when the stent is formed by thermal spraying or electroforming, for example, by treating the surface of the molding base (base material) with a protrusion or the like, the inner surface of the stent formed on the surface is processed. A recess having a size corresponding to the peripheral surface can be transferred and formed. Further, by forming an island-shaped mask on the central portion of the surface of the skeleton formed in advance and performing thermal spraying or electroforming, a peripheral wall surrounding the island-shaped mask portion is formed, and the central mask portion It is also possible to form a recess opening in the outer peripheral surface of the stent. Such a medicine receiving recess 70 can be formed in any shape and size, and other than the groove shape extending in the length direction of the annular portion 12 and the link portion 14 as shown in FIG. It may be a hole such as a circle. When such a stent is produced by thermal spraying or electroforming, it is possible to form a recess of any size on the surface by appropriately setting the shape of the molding base and mask used, The degree of freedom of design can be greatly secured.

  Further, when the stent is formed by electroforming, for example, using a eutectoid plating technique using an electrolytic solution in which a non-conductive powder is dispersed, a porous structure or microporous corresponding to the eutectoid fine particles is used. It is also possible to give the structure to the annular part 12 and the link part 14.

  Thus, the metal amount which comprises a stent can be reduced by forming the cyclic | annular part 12 and the link part 14 with the chemical | medical agent accommodation recess 70 or a porous structure. In addition, by loading the drug in the drug containing recess 70 or the porous structure, for example, a drug-eluting stent as described above can be formed, and the drug can be effectively eluted into the blood vessel wall.

  Furthermore, the medicine accommodating recess 70 formed in the stent may be not only a bottomed shape but also a through hole. By forming the through hole in the stent in this way, the loading of the drug can be further facilitated and the amount of the drug loaded can be increased. In addition, since the through-hole becomes hollow after the drug or the like is eluted, blood can pass through the through-hole. For example, blood flow is inhibited as compared with the case where the recess is bottomed. Therefore, the effect of preventing turbulent flow and restenosis can be exhibited.

  Further, the medicine may be directly placed in the medicine housing recess 70, for example, a biodegradable resin cotton impregnated with the medicine or a capsule filled with the medicine is placed in the medicine housing recess 70. Also good.

  Furthermore, the unevenness formed on the stent may be formed directly on the surface of the stent. For example, by forming a convex portion on the surface of the stent, a relatively concave portion is formed. May be.

  The stent 10 may be provided with an ultrasonic marker 72 as shown in FIG. The ultrasonic marker 72 is made of resin or metal, and has a large number of minute voids 74 therein. The minute voids 74 contain a gas such as air. And the ultrasonic marker 72 is excellent under the fluoroscopic perspective because the irradiated ultrasonic wave is reflected at the boundary between the solid part formed of resin or metal and the gas phase of the minute gap 74. Visibility is demonstrated.

  The microscopic voids 74 of the ultrasonic marker 72 may have a porous structure that is continuous to some extent, but it is desirable that the microscopic voids 74 be made of a liquid such as blood. It becomes difficult to satisfy, and high visibility under ultrasonic fluoroscopy can be maintained for a long time. However, the minute gap 74 does not necessarily need to be filled with gas, and may be filled with a liquid, or an individual made of a material different from the solid portion may be accommodated.

  The ultrasonic marker 72 is formed by thermal spray molding, for example. In other words, the spraying density of spray particles is set to be small during spray forming, a relatively large number of pores and a coarse spray coating is formed. The ultrasonic marker 72 having the minute gap 74 can be easily formed. In particular, in the case of thermal spray molding, it is possible to select a molding material from a wide range of resin materials and metal materials, and a molding material that takes into account the required characteristics such as biodegradability and biocompatibility can be selected with great flexibility. can do. However, the method of forming the ultrasonic marker 72 is not limited to thermal spraying, and can be formed by etching in addition to vacuum deposition and electroforming, which are the same film formation techniques as thermal spraying.

  The ultrasonic marker 72 having such a structure is applied to, for example, a stent as shown in FIGS. That is, FIG. 12 shows a covered stent 76 used as a flow diverter or a stent graft. The covered stent 76 has a structure in which a stent main body 80 composed of a plurality of annular portions 78 arranged away from each other in the axial direction is fixed to the outer peripheral surface of a cylindrical cover 82 formed of a resin thin film such as PTFE. Has been. As shown in the embodiment, the annular portion 78 has a shape that extends in the circumferential direction while undulating in the axial direction, and has at least one of self-expandability by superelasticity and mechanical expandability using a balloon stent or the like. I have.

  And the ultrasonic marker 72 of this aspect is integrally fixed to the surface of the stent main body 80 or the surface of the cover 82, for example. This improves the visibility of the covered stent 76 under ultrasonic fluoroscopy, and makes it easier to grasp the position of the covered stent 76 in the stent placement under echo.

  The ultrasonic marker 72 can also be applied to a stent that does not have the cover 82, such as the stent retriever 84 shown in FIG. The stent retriever 84 is a cylindrical mesh-type stent-type thrombectomy device, for example, for pressing and removing a thrombus with a net to remove it. Further, in the stent retriever 84, the entire skeleton has a structure including the minute gap 74, and the skeleton itself is the ultrasonic marker 72. Thus, the ultrasonic marker 72 is not limited to the one provided on the surface of the stent, and for example, the entire skeleton of the stent may be the ultrasonic marker 72. Furthermore, in the case where the skeleton of the stent itself is the ultrasonic marker 72, the microvoids 74 are continuously penetrating into the surface so that the blood contact area with the blood vessel wall becomes large and less invasive. In addition, the indwelling position can be stabilized by fine surface roughening.

  Note that the ultrasonic marker 72 as described above is not necessarily applied only in an aspect combined with the present invention, and may be applied to, for example, a medical device other than a stent. Specifically, the present invention can be applied to a catheter 86 as shown in FIG. 14, a coil 88 for stagnating the blood flow of an aneurysm as shown in FIG. 15, a guide wire used for introducing a catheter, and the like. The ultrasonic marker 72 is improved in visibility even when the position is confirmed using, for example, IVUS (intravascular ultrasound), and the position is easily grasped. As understood from this, the invention relating to the ultrasonic marker 72 can also be recognized as an independent invention that can solve a different problem from the present invention.

  That is, the first aspect of the present invention is a medical device to be inserted into a body lumen, comprising an ultrasonic marker formed of a sparsely structured structure having a minute gap inside, and the ultrasonic marker. Is formed by at least one of thermal spraying, vapor deposition, etching, and electroforming.

  According to a second aspect, in the medical device according to the first aspect, at least one of a catheter, a stent, a coil, and a thrombectomy device provided with the ultrasonic marker is used.

  A 3rd aspect is a stent provided with the cylindrical frame | skeleton which can be expanded / contracted in the medical device which concerns on the said 1st or 2nd aspect, Comprising: This frame | skeleton is used as the said ultrasonic marker.

  In addition, the shape of the stent is not limited to a simple straight shape as illustrated in the above embodiment or a shape in which a thick portion is provided at an end or center in the length direction, but a tapered cylindrical shape, Thick end shape, Y-shaped branch shape including a main cylinder portion and a branch cylinder portion, a shape in which the diameter of the main cylinder portion and the branch cylinder portion are different in the Y-shaped branch shape, The present invention is applicable to various types of irregularly shaped stents, such as at least one having a tapered cylindrical shape and a shape partially tapered in the length direction.

  Furthermore, the rigidity of both end portions in the axial direction of the stent may be increased by making the both end portions in the axial direction of the stent thick or adopting a metal having high rigidity as both end portions in the axial direction. According to this, lifting from the blood vessel at both axial end portions of the stent is suppressed, and the stent is stably placed at the stenosis site of the blood vessel. In particular, since the lift from the blood vessel is suppressed at both axial ends of the stent, the risk of thrombus formation due to blood flow disturbance is reduced, and restenosis can be effectively prevented.

  Furthermore, in the skeleton of the stent 10, the cross-sectional shapes of the annular portion 12 and the link portion 14 may be different. However, in the stent of the present invention, the link portion is not essential, and the annular portions adjacent in the axial direction of the stent may be continuously connected in a spiral structure. In this case, there is no need to provide a link portion, and the skeleton of the stent can be formed without the link portion. Furthermore, it is also possible to adopt a skeleton having a mesh structure as a whole by a plurality of struts extending in a spiral shape opposite to each other. Further, when the stent having the self-expanding region 56 and the overdeformed region 58 as shown in the first to fourth embodiments of the present invention is formed in a structure in which the struts are spirally continuous, By forming partly with a shape memory material in the longitudinal direction, a stent with a self-expanding region 56 partially in the axial direction is realized.

  Furthermore, the thickness dimension and cross-sectional shape of the strut need not be uniform over the entire length. For example, it may be partially thick or thin in the length direction of the strut. Moreover, when not providing a link part as mentioned above, a weak part may be formed of the thin part of the strut.

  Furthermore, a stent having a structure according to the present invention may be formed by electroforming or vacuum deposition known as a molding technique such as film formation as in the case of thermal spraying. For example, a molded base is immersed in an electrolytic bath in which a predetermined metal is ionized to form a stent by electrodepositing metal ions and integrating them into a predetermined shape, or particles of a material that is vaporized or sublimated by heating. It is also possible to form a stent by integrating a large number of these into a predetermined shape. Even when the stent is formed by electroforming or vacuum deposition, it can be easily manufactured by appropriately masking the surface of the molding base. It is also possible to form a stent with a predetermined shape by etching. That is, a stent can be formed by removing unnecessary portions of a cylindrical body made of a predetermined material with a chemical solution or an active group by gas discharge.

  16 to 28 show stents 90, 104, 106, 108, 110, and 112 that can be recognized as independent inventions that can solve problems different from the present invention. These stents 90, 104, 106, 108, 110, 112 are formed by, for example, the above-described spraying, vapor deposition, etching, electroforming, or the like.

  The stent 90 shown in FIG. 16 includes a substantially cylindrical shape and a trunk cylinder portion 92 and a branch cylinder portion 96 that extend linearly, and a branch portion provided at an intermediate portion in the length direction of the trunk cylinder portion 92. As a whole, the branch cylinder portion 96 is inclined to the side from 94 and extends to have a substantially Y-shaped branch shape. In other words, in the stent 90 of the present embodiment, the number of tube portions is different in the length direction (vertical direction in FIG. 16) by the branch portion 94, that is, the stent 90 has a cross-sectional shape in the length direction. It is an irregularly shaped cylinder shape that changes.

  Each of the trunk tube portion 92 and the branch tube portion 96 is provided with a plurality of annular portions 98 that are continuously curved and bent in a wavy shape and extend in the circumferential direction at a predetermined distance from each other in the axial direction. As a result, a series of struts 102a constituting the trunk cylinder portion 92 and a series of struts 102b constituting the branch cylinder portion 96 are formed. And the annular parts 98 and 98 adjacent to each other in the axial direction in the struts 102a and 102b are respectively connected by the link parts 100 extending in the substantially axial direction, thereby forming a cylindrical shape having a predetermined length.

  In particular, in the present embodiment, in the branch portion, the annular portion 98 that constitutes the basic cylinder portion 92 and the annular portion 98 that constitutes the branch cylinder portion 96 are continuous on the circumference of the basic cylinder portion 92 and the branch cylinder portion 96. It extends. Thereby, the integral structure of each strut 102a, 102b is implement | achieved in the branch part of the basic cylinder part 92 and the branch cylinder part 96, and the continuous strut 102 is comprised. In the strut 102, the skeleton of the stent 90 of the present embodiment is configured by connecting the annular portions 98 and 98 adjacent in the axial direction by the link portion 100. As a result, the strength and the degree of freedom of deformation of the stent 90 are improved, and local deformation such as buckling of the strut 102 during deformation is prevented.

  The specific shapes of the annular portion 98 and the link portion 100 are not limited in the present invention, and the wave shape of the annular portion 98 and the connection by the link portion 100 are considered in consideration of the characteristics required for the stent 90. A part, the number of the link parts 100 on the periphery of the annular part 98, etc. can be set suitably.

  Further, the width dimension and the thickness dimension of the annular portion 98 and the link portion 100 are not particularly limited, but the strut 102 constituting the annular portion 98 is about 30 to 200 μm in order to ensure the strength. The width dimension and the thickness dimension are desirable, and the link portion 100 is desirably a width dimension and a thickness dimension of about 10 to 100 μm.

  Such a branched stent 90 is manufactured by integrally forming a plurality of annular portions 98 and link portions 100 constituting the struts 102 by electroforming.

  Specifically, a molding base having the shapes and sizes of the target trunk cylinder portion 92 and the branch cylinder portion 96 is prepared by using a conductor such as stainless steel. Then, on the surface of the molding base, an exposed surface is formed in a shape corresponding to each of the plurality of annular portions 98 and the link portions 100, and a non-conductive mask is applied to other regions. Then, it is immersed in an electrolytic bath in which a predetermined metal is ionized, and metal ions are electrodeposited on the exposed surface of the molding base to perform electroforming. After obtaining a metal having a predetermined thickness, the mask 90 is removed, and the molded base is extracted or dissolved to obtain the stent 90 having the above-described target structure.

  The stent 90 of this embodiment having the above-described structure is capable of expanding and contracting in the radial direction in the trunk cylinder portion 92 and the branch cylinder portion 96, and has a predetermined dimension from the state before contraction shown in FIG. The diameter is reduced mechanically. In use, the stent 90 is delivered to, for example, a stenosis site of a blood vessel by a delivery catheter or the like. Thereafter, the stent 90 is expanded by a balloon catheter, or when the stent 90 is formed of a shape memory material, the stent 90 is automatically expanded by being released from the delivery catheter, and in the state shown in FIG. Etc. are placed in the body lumen.

  Since the stent 90 of this aspect is produced by electroforming, a branched shape having the basic cylindrical portion 92 and the branched cylindrical portion 96 can be integrally formed. Therefore, compared to the case where two stents obtained by laser processing straight cylindrical metal fittings as in the conventional structure are joined to form a branched shape, the portion to be excised can be reduced, The yield can be improved and a complicated branch shape can be obtained with high accuracy. Therefore, it is possible to realize the stent 90 with high yield with respect to a complicated shape part such as a blood vessel of a living body with high accuracy.

  In addition, since it is manufactured by electroforming as described above, the degree of freedom in design of the shape is greatly improved while ensuring the integral formability of the stent 90. Compared to the obtained stent, it is possible to obtain a stent with various irregular initial shapes.

  For example, as shown in FIG. 17, the stent 104 as another embodiment having a tapered cylindrical shape whose inner and outer diameter dimensions change in the axial direction is also integrally formed by electroforming with an initial shape of a target taper angle. Can do. The stent 104 of the present embodiment has such a tapered shape and a deformed cylindrical shape whose cross-sectional shape changes in the length direction. In the following description, the same members and parts as those in the above-described aspect are denoted by the same reference numerals as those in the above-described aspect, and detailed description thereof is omitted.

  Since such a stent 104 is tapered in an initial shape when placed in a blood vessel or the like whose diameter is changed, distortion and residual stress in the placed state can be suppressed.

  Further, since the skeletons of the stents 90 and 104 as described above, that is, the struts 102 and the link part 100 are manufactured by electroforming, it is possible to form a laminated structure of different materials. Specifically, after forming a non-conductive mask on the surface of the molding base as described above and performing the first electroforming, the electroforming is performed in the second electrolytic bath of another metal ion. By performing the casting, a metal layer of another material can be formed on the surface of the metal formed by the first electroforming by the second electroforming. As can be seen from this, the invention of this aspect can be adopted in combination with the inventions according to the first to fourth embodiments of the invention according to the parent application. Similarly, the invention of this aspect can be employed in combination with the inventions according to the first to fourth embodiments of the present invention.

  Such a laminated structure of metals can be performed any number of times, for example, a structure in which a surface layer portion is provided by coating another metal so as to cover a core portion formed of a specific metal is also possible. It is. In that case, for example, it is preferable that the metal of the surface layer portion has a higher ductility than the metal of the core portion. As a result, the followability when the stent is bent is improved, and the concentration of strain and stress in the surface layer portion is avoided.

  Further, it is preferable that the metal in the surface layer portion has a smaller ionization tendency than the metal in the core portion. Specifically, for example, the core portion is formed of stainless steel (SUS316L), CrCo alloy, tantalum, NiTi, etc., while the surface layer portion is Ni, NiCo, Cu, NiW, Pt, Au, Ag, Cr, Zn, etc. Preferably, it can be formed of Au or Pt. Accordingly, it is possible to improve biocompatibility by suppressing the potential difference from the living body with the metal in the surface layer portion while efficiently ensuring strength and rigidity with the metal constituting the core member. Moreover, since the ionization tendency of Au, Pt, etc. is very low, metal elution can be suppressed. Furthermore, elution of metal ions that cause metal allergy such as Ni used in the alloy as the core material can be suppressed. Moreover, since Au, Pt, etc. have a large specific gravity and good radiopacity, the visibility of a stent using X-rays can be improved.

  In addition, after performing the first electroforming, it is also possible to re-form the mask and perform the second electroforming. Accordingly, for example, the annular portion 98 and the link portion 100 can be formed of different metal materials, and the material of the annular portion 98 can be partially different in the length direction and the circumferential direction of the stent 90. become.

  Specifically, as still another aspect, as shown in FIG. 18, in the straight cylindrical stent 106, only one or a plurality of annular portions 98 positioned at the axial ends thereof are provided. The thickness can be increased by increasing the number of times of electroforming as compared with the other annular portion 98 located in the central portion in the axial direction. That is, in the stent 106 of the present embodiment, the cross-sectional shape changes in the length direction with a shape in which the thickness dimension changes in the length direction. In addition, by making the axial end portion thicker than the central portion, the axial end portion may have a larger outer diameter size, a smaller inner diameter size, or both than the central portion. . Moreover, this thick part may be provided in one edge part of an axial direction, and may be provided in an axial direction both ends.

  As described above, in the deformed cylindrical stent 106 in which the axial end portion is thicker than the central portion, the rigidity of the axial end portion is made larger than that of the central portion. It is also possible to prevent restenosis by suppressing the lifting from the blood vessel at the axial end while securing the degree of freedom.

  In addition, after the first electroforming, the mask is formed again, and the second electroforming is performed so as to straddle over the annular portions 98 and 98 adjacent to each other located at the end in the axial direction. It is also possible to form an annular portion 98 that is offset by a half pitch in the axial direction so as to cover the outer periphery. Since it is possible to reinforce the rigidity of the axial end portion with such a complicated structure, a large degree of freedom in design is realized.

  In the stent 106 of this embodiment, it is preferable that the rigidity of the end portion on the outer side in the axial direction is substantially the same as or smaller than that of the central portion at the axial end where the rigidity is increased compared to the central portion. . Thereby, the load which the axial direction terminal part of the stent detained so that it may bite into the blood vessel wall can exert on the blood vessel wall can be reduced. Such a rigid end portion can be realized, for example, by forming only the end portion with a soft metal, or by adjusting the number of times of electroforming, a mask or the like to reduce the thickness or width of the end portion.

  Furthermore, since the stents 90, 104, and 106 as described above are manufactured by electroforming, the design freedom of the cross-sectional shape of the struts 102 constituting the skeleton is also simple rectangular cross-section in the conventional laser processing. On the other hand, a large degree of freedom can be secured. For example, FIGS. 19A and 19B show the cross-sectional shape of the strut 102 whose width dimension changes from the inner peripheral surface toward the outer peripheral surface. That is, in the embodiment shown in FIGS. 19A and 19B, the cross-sectional shape of the strut 102 has a deformed structure that changes in the thickness direction. In FIGS. 19A and 19B, the upper side is the outer peripheral side, that is, the side in contact with the blood vessel wall, and the lower side is the inner peripheral side, that is, the side located in the blood vessel lumen.

  Specifically, as shown in FIG. 19A, a strut 102 having a substantially triangular cross section can also be used. In the strut 102 having such a shape, the width dimension is reduced from the inner peripheral surface toward the outer peripheral surface, and the side in contact with the blood vessel wall is gradually narrowed. Therefore, when the stent is expanded, the pressing force against the blood vessel wall of the stent is increased. Can be concentrated on the tapered portion of the strut 102. As a result, the blood vessel can be expanded with a smaller pressing pressure of the stent, in other words, with the expansion pressure of the stent. In addition, even when the blood vessel wall is hard, such as a calcified lesion of a blood vessel, the taper portion of the strut 102 bites and breaks against the calcified lesion portion, so that it is difficult to expand with a conventional rectangular cross section. Vascularized vessels can also be dilated.

  Further, as shown in FIG. 19B, a strut 102 having a substantially inverted triangular cross section can also be employed. In the strut 102 having such a shape, the width dimension is reduced from the outer peripheral surface toward the inner peripheral surface, and the side located in the blood vessel lumen is gradually narrowed. It can be suppressed as much as possible. Moreover, since it is difficult for stagnation to occur in the blood flow, the risk of blood clots and the like being generated can be reduced. Furthermore, since the area exposed to the blood vessel lumen is small, the period until it is covered with the vascular endothelial cells can be shortened, and the strut 102 is buried in the blood vessel at an early stage. From this, the enlargement of the vascular endothelium can be suppressed, and the stent placement portion can be cured in a relatively short period of time.

  The strut 102 having such a shape can be formed by adjusting the shape of the mask during electroforming to a desired shape by etching or the like, and can greatly improve the degree of freedom of setting the cross-sectional shape. That is, a stent whose cross-sectional shape changes in the thickness direction as shown in FIGS. 19A and 19B can be easily manufactured by electroforming only by appropriately setting the masking shape. However, the cross-sectional shape of the strut 102 is not limited to the approximate triangular shape or the generally inverted triangular shape shown in FIGS. 19A and 19B, and for example, a semicircular shape or a double tapered shape is also employed. Can be done.

  Furthermore, since the stents 90, 104, and 106 as described above are manufactured by electroforming, the cross-sectional shape of the link portion 100 that connects the annular portions 98 and 98, as well as the degree of freedom in designing the strength and the brittleness are greatly increased. Can be secured. In this way, by providing a partially low-strength portion in the skeleton of the stent, the fragile portion applied when the expanded stent is bent is easily deformed or cut, so that the stent has a shape of a body lumen. It is easy to follow. In addition, when an opening is formed in a stent corresponding to a branched blood vessel or the like, an operator can easily perform an operation of cutting or expanding the fragile site.

  Here, in the stents 90, 104, and 106, in the skeleton, a weakened portion whose strength is smaller than that of the annular portion 98 is configured by the link portion 100. By producing such a link portion 100 by electroforming, only a thin shape in the width direction of the strut 102 can be formed by laser processing of the conventional structure, but not only the thin shape but also the thickness of the strut 102. Thin shapes can also be formed in the vertical direction. Moreover, the cross-sectional shape of the link part 100 was only a simple rectangular cross section by the conventional laser processing, but shapes other than a rectangle can also be formed.

  Specifically, for example, as shown in FIGS. 20A to 20C, the design of the position of the link portion 100 in the thickness direction can be appropriately changed with respect to the annular portions 98 and 98. In FIG. 20, the upper side shows the blood vessel wall side, and the lower side shows the blood vessel lumen side. That is, in FIG. 20 (a), the annular portions 98, 98 are connected by the link portion 100 on the blood vessel wall side, while in FIG. 20 (b), the annular portions 98, 98 are the link portions at the central portion in the thickness direction. 100 are connected. In FIG. 20C, the annular portions 98 and 98 are connected by the link portion 100 on the blood vessel lumen side. Furthermore, it is possible to combine the link portions 100 positioned on the blood vessel wall side, the central portion, and the blood vessel lumen side. In FIG. 20, the strut 102 and the link portion 100 are shown as a rectangular cross section, but FIG. 20 simply shows the relative positions of the annular portions 98 and 98 and the link portion 100, and the strut 102 and the link portion 100. The shape of is not limited in any way.

  Thus, in conventional laser processing, since one pipe is formed to penetrate in the thickness direction, the annular portion and the link portion can only be formed with the same thickness, whereas the stent 90 , 104, 106 are manufactured by electroforming, the thickness dimension of the link portion 100 can be reduced. Thereby, the link part 100 can be formed thinly and thinly, and when the link part 100 is cut | disconnected, it is made easy to cut | disconnect more easily than before. Conventionally, a method of forming the annular portion 98 and the link portion 100 separately and then fixing them together has been adopted. However, by manufacturing the stents 90, 104, and 106 by electroforming, The link part 100 is integrally formed, and manufacturing can be facilitated while ensuring high dimensional accuracy. Furthermore, since the cut surface of the link part 100 is made small, irritation | stimulation by a cut surface contacting a blood vessel wall etc. can be suppressed as much as possible.

  Further, the design of the position of the link portion 100 can be changed as appropriate in the width direction of the strut 102, and it can be formed at the end in the width direction with respect to the strut 102, but is shown in FIG. As described above, the link portion 100 is preferably formed in the center portion in the width direction of the strut 102, that is, in the center portion in the width direction in the bent portion of the annular portion 98 in the above-described embodiment. In particular, as shown in FIG. 21, the link portion 100 is preferably located at the central portion of the strut 102 in the thickness direction. Thereby, the possibility that the cut surface of the link part 100 contacts the blood vessel wall is further reduced, and the discomfort given to the patient can be further reduced.

  21 also shows the strut 102 and the link portion 100 as a rectangular cross section, but FIG. 21 merely shows the relative positions of the annular portion 98 and the link portion 100. The shape is not limited at all.

  Next, FIGS. 22 and 23 show a stent 108 as still another embodiment. The stent 108 is generally cylindrical and extends linearly as a whole.

  Here, the cross-sectional shape of the strut 102 in the stent 108 of this embodiment is formed as a deformed structure that is different in the thickness direction (vertical direction in FIG. 19B) as shown in FIG. 19B. The width dimension (the dimension in the left-right direction in FIG. 19B) is increased from the inner peripheral surface toward the outer peripheral surface.

  That is, in this aspect, the cross-sectional shape of the strut 102 is an approximately inverted triangle. Further, in this embodiment, the edge portion in the inverted trapezoidal cross-sectional shape shown in FIG. 23B is subjected to chamfering such as sand blasting, chemical polishing, electrolytic polishing, etc., so that it is shown in FIG. 19B. A generally inverted triangular cross-sectional shape is formed. In the cross-sectional shape before chamfering shown in FIG. 23 (b), if the width dimension of the outer peripheral surface is W, it is preferably 60 mm ≦ W ≦ 180 mm, and more preferably 80 mm ≦ W ≦ 130 mm. It is set within the range, and in this embodiment, W = 125 mm.

  Therefore, in this aspect, as shown in FIG. 24, the central angle β in the arc of the inner peripheral surface is made smaller than the central angle α in the arc of the outer peripheral surface of the strut 102 (β <α). That is, two points A and B on the outer peripheral surface where the width dimension is the largest in the cross-sectional shape of the strut 102 before the chamfering process (thick one-dot chain line in FIG. 24) pass through these points A and B. An arc Co that is convex to the side and a center of curvature O located on the inner peripheral side of the strut 102 are assumed as the center of curvature of the arc Co. Further, assume that two points on the inner peripheral surface of the strut 102 having the smallest width dimension in the cross-sectional shape of the strut 102 before the chamfering process are D and E, and an arc Ci passing through the points D and E with the point O as the center of curvature. To do. Here, when ∠AOB is the central angle α in the arc of the outer peripheral surface of the strut 102, and ∠DOE is the central angle β in the arc of the inner peripheral surface of the strut 102, the central angle β in the strut 102 is greater than the central angle α. It is also small. In this aspect, since the cross-sectional shape of the strut 102 is an approximately inverted triangle, it is understood that the central angle β in the arc of the inner peripheral surface of the strut 102 is substantially 0 (β≈0).

  Further, in this aspect, the depression angle θ on both side surfaces is made larger (α <θ) than the central angle α in the arc of the outer peripheral surface of the strut 102. The depression angle θ is formed by the intersection of the straight line AD and the straight line BE in FIG. 24 in the cross-sectional shape of the strut 102 before the chamfering process.

  The central angle α of the outer peripheral surface is preferably 1 ° ≦ α ≦ 45 °, and more preferably 4 ° ≦ α ≦ 15 °. On the other hand, the central angle β of the inner peripheral surface is preferably set to 0 ° ≦ β ≦ 30 °, and more preferably set within a range of 0 ° ≦ β ≦ 10 °. Further, the depression angle θ on both side surfaces is preferably set to 15 ° ≦ θ ≦ 90 °, and more preferably set within a range of 30 ° ≦ θ ≦ 90 °. By setting the center angles α and β of the outer peripheral surface and the inner peripheral surface and the depression angles θ of both side surfaces within the above ranges, the effect of preventing fluid turbulence and the effect of reducing the outer diameter at the time of diameter reduction are stabilized. Can be demonstrated.

  The stent 108 of this embodiment having such a shape is manufactured as a metal skeleton in which the struts 102 and the link portions 100 as the skeleton are integrally formed by electroforming.

  The stent 108 of this embodiment is capable of expanding and contracting in the radial direction. The stent 108 is mechanically contracted from a state before contraction shown in FIG. 22 to a predetermined size, and contracted as shown in FIGS. State. FIG. 25 shows one of the annular parts 98 constituting the stent 108, and the illustration of the other annular part 98 and the link part 100 connecting the annular parts 98, 98 is omitted.

  Here, the cross-sectional shape of the strut 102 is an approximately inverted triangle as shown in FIG. 19B, and when the diameter is reduced, the circumferential direction in the strut 102 is formed at both axial end portions of the annular portion 98. Adjacent parts abut. At that time, as shown in FIG. 26 (b), the peripheral end portions on the outer peripheral side in the cross-sectional shape of the strut 102 are in contact with each other, so that the diameter of the stent 108 is limited and the diameter of the stent 108 is reduced. The outer diameter dimension of the stent 108 is defined.

  In the stent 108 of this embodiment having the above-described structure, since the cross-sectional shape of the strut 102 is a substantially inverted triangle, for example, compared to a stent having a conventional structure having a rectangular cross-section, the stent 108 has an internal structure. The part exposed to the peripheral blood flow can be reduced. This prevents the stent 108 from obstructing the blood flow and prevents the blood flow from becoming slow or turbulent (turbulent) due to the stent 108 being placed in the blood vessel. Is done. Therefore, the formation of a thrombus in a blood vessel or heart due to turbulence is suppressed, and restenosis at the indwelling position of the stent 108 due to the attachment of the thrombus to the stent 108 is effectively prevented. obtain.

  Moreover, since the area exposed from the blood vessel wall is reduced, it is buried in the vascular endothelial cell at an early stage. That is, since the blood vessel wall that has cracked due to the placement of the stent 108 can be healed in a relatively short time, the enlargement of the vascular endothelial cells is suppressed and a thrombus adheres to the enlarged vascular endothelial cells. Thus, restenosis at the indwelling position of the stent 108 can be avoided. However, even if the vascular endothelial cells are enlarged, a lot of gaps are formed on the inner peripheral side of the stent 108, so that the vascular endothelial cells enter the gaps and the growth of the vascular endothelial cells to the inner peripheral side is suppressed. Thus, the risk of restenosis at the indwelling position of the stent 108 can be further reduced.

  Furthermore, for example, in a stent in which the skeleton of the conventional structure has a rectangular cross section, when the diameter is reduced, the corners on the inner peripheral side of the skeleton cross section quickly contact each other, and the further diameter reduction is limited. In the stent 108, since the cross-sectional shape of the strut 102 is an approximately inverted triangle, the strut 102 does not abut on the inner peripheral side of the strut 102 but abuts on the outer peripheral side. As a result, the stent 108 of this embodiment is not limited in diameter reduction as compared with a stent having a conventional structure, and the outer diameter dimension at the time of diameter reduction can be further reduced. In particular, as in this aspect, by increasing the depression angle θ on both side surfaces compared to the central angle α of the outer peripheral surface, the possibility of contact on the inner peripheral side is further reduced, so the outer diameter size at the time of diameter reduction Can be reliably reduced. As a result, the delivery of the stent 108 and the delivery catheter equipped with the stent 108 can be improved.

  In particular, in the cross-sectional shape of the strut 102, it is preferable that the depression angle θ on both sides is set to 15 ° ≦ θ ≦ 90 °, whereby the circumferential dimension in the cross-sectional shape of the strut 102 can be kept small. For example, even when the wave number in the circumferential direction of the stent (the number of repeating units in the circumferential direction) is large, the outer diameter dimension when the diameter is reduced can be stably reduced.

  Next, FIG. 27 shows a stent 110 as still another embodiment. The stent 110 of this aspect has a skeleton structure composed of the struts 102 and the link portions 100, and the cross-sectional shape of the struts 102 is the shape shown in FIG.

  The stent 110 according to this aspect has a deformed cylindrical shape in which the outer diameter dimension at both end portions in the axial direction (vertical direction in FIG. 27) is larger than the outer diameter dimension at the central portion in the axial direction. The stent 110 of this aspect is, for example, a plurality of annular portions 98 positioned at both axial end portions relative to the straight cylindrical stent 108 shown in FIG. 22 than the annular portion 98 positioned at the axial central portion. Also, it can be formed by increasing the number of times of electroforming to make it thick. That is, it is preferable that the stent 110 of this aspect has a laminated structure made of a plurality of types of metals. Such a laminated structure does not need to be formed over the entire stent, and a specific portion of the stent may be a laminated structure. Further, the shape of the inner hole of the stent 110 is not limited in any way. For example, a straight shape extending in the axial direction may be used, and both end portions may have larger diameters than the central portion in the axial direction.

  Furthermore, the stent 110 according to this aspect has both end portions in the axial direction being thicker than the central portion in the axial direction, so that the rigidity of both end portions is increased compared to the central portion.

  Also in the stent 110 of this embodiment having the above-described shape, since the cross-sectional shape of the skeleton is the same as that of the stent 108, the same effect as that of the stent 108 can be exhibited. In addition, in this aspect, since both end portions in the axial direction are larger in outer diameter than the central portion in the axial direction and have increased rigidity, the axial end portions of the stent 110 are lifted from the blood vessel. Suppressed and stably placed at the stenosis site of the blood vessel. In particular, when the axial end of the stent is separated from the blood vessel in a state where it is placed in the blood vessel, there is an increased possibility that blood flow is disturbed and a thrombus is formed. Therefore, as shown in this aspect, the lift from the blood vessel is suppressed at both axial ends of the stent 110, so that restenosis at the stent placement position can be more effectively prevented. Furthermore, by reducing the rigidity of the axial end portion, the load exerted on the blood vessel wall by the axial end portion of the stent placed so as to bite can be reduced.

  Next, FIG. 28 shows a stent 112 as another embodiment. The stent 112 of this embodiment has a substantially Y-shaped skeleton structure composed of the struts 102 and the link portions 100, and the cross-sectional shape of the struts 102 is the shape shown in FIG.

  The stent 112 of this embodiment may be formed by, for example, forming the main cylinder portion 114 and the branch cylinder portion 116 separately and joining them together by means such as welding. 114 and the branch cylinder part 116 may be formed integrally.

  Also in the stent 112 of this embodiment having such a shape, since the cross-sectional shape of the strut 102 is the same as that of the above-described embodiment shown in FIG. 19, the same effect as the stent 108 of this embodiment is exhibited. obtain. In particular, the stent 112 according to this embodiment has a branched shape and can correspond to a complicated shape such as a blood vessel of a living body, and blood flow disturbance is suppressed even at the branched portion of the blood vessel, thereby further reducing the restenosis of the blood vessel. It can be effectively prevented.

[Example]
As Example 1 of this invention, a stent 108 having a structure according to the embodiment shown in FIG. 19 shown in FIGS. 22 and 23 was virtually manufactured on a computer. Further, as Example 2 of the present invention, as shown in FIG. 29, a stent 118 is adopted in which the cross-sectional shape of the skeleton is reduced to a width dimension from the inner peripheral surface toward the outer peripheral surface to form an approximate triangle. As a comparative example, a stent 120 having a conventional structure with a rectangular cross section as shown in FIG. 30 was employed, and each was virtually fabricated on a computer. In addition, while Example 2 and the stent 118,120 of a comparative example shown by FIG.29,30 have shown the thing of the shaping | molding state before diameter reduction, these stents of Examples 1,2 and comparative example 108, 118 and 120 were prepared assuming that the edge portions were not chamfered.

  Further, the outer diameters of the stents 108, 118, and 120 of Examples 1 and 2 and the comparative example before the diameter reduction were each set to φ = 3 mm (see FIG. 22). Furthermore, while the width dimension of the outer peripheral surface of the cross section of the strut 102 in the first embodiment is W = 125 mm (see FIG. 23B), the width dimension of the inner peripheral surface of the cross section of the strut 102 ′ in the second embodiment (FIG. b) was also designated W. Furthermore, the width dimension of the outer peripheral surface of the cross section of the strut 122 in the comparative example was W1 = 100 mm (see FIG. 30B). In addition, the thickness dimensions of the struts 102, 102 ', 122 of Examples 1 and 2 and the comparative example were set to the same T = 0.1 mm (see FIG. 23B, etc.).

  Then, diameter reduction processing was performed on the stents 108, 118, and 120 of Examples 1 and 2 and the comparative example that were virtually manufactured on a computer, and the respective outer diameter dimensions were compared. The perspective view and the axial view of the annular portion 98 obtained by reducing the diameter of the stent 108 of Example 1 are shown in FIGS. 25 and 26, and the stent 118 of Example 2 and the comparative example. , 120 are a perspective view and an axial view of the annular portion 98 obtained by reducing the diameter. Thus, the outer diameter dimensions of the stents 108, 118, 120 of Examples 1 and 2 and the comparative example subjected to the diameter reduction treatment are φ ′ (see FIG. 26A), φ1 (see FIG. 32), and φ2, respectively. (See FIG. 34). In addition, “ANSYS R14.5” manufactured by ANSYS was used as software for performing analysis by performing such a diameter reduction process.

  As a result, φ1 = 1.80 mm and φ2 = 1.70 mm, whereas φ ′ = 1.68 mm. That is, the stent 108 in which the cross-sectional shape of the strut 102 is an approximately inverted triangle is the same as the stent 118 in which the cross-sectional shape of the strut 102 ′ is an approximate triangle or the stent 120 in which the cross-sectional shape of the strut 122 is a conventional structure. On the other hand, it is shown that the outer diameter size when the diameter reduction process is performed becomes smaller.

  The reason why the outer diameter of the stent 108 of Example 1 is smaller than that of the stent 118 of Example 2 and the stent 120 of Comparative Example after the diameter reduction processing is that in the stents 118 and 120 of Example 2 and Comparative Example, FIG. As shown in FIG. 32 (b) and FIG. 34 (b), when the diameter reduction process is performed, the inner peripheral sides of the skeletons adjacent in the circumferential direction are brought into contact with each other quickly, and further diameter reduction is limited. Is done. On the other hand, as shown in FIG. 26B, the stent 108 of Example 1 has a skeleton that is adjacent in the circumferential direction because the width of the inner peripheral surface is smaller than the width of the outer peripheral surface. It is surmised that the diameter reduction is not limited until the outer peripheral sides of the two come into contact with each other, and the outer diameter dimension becomes smaller.

  As a result, the outer diameter of the stent 108 of the first embodiment can be made smaller than that of the stent 118 having the substantially triangular cross section of the second embodiment and the stent 120 having the rectangular cross section of the conventional structure. Since the outer diameter at the time of mounting can be reduced, good delivery can be exhibited.

  Moreover, the flow velocity in the vicinity of each strut was confirmed using the stents 108, 118, and 120 of Examples 1 and 2 and the comparative example. The results of Examples 1 and 2 are shown in FIGS. 35 and 36, respectively, and the result of the comparative example is shown in FIG. In addition, the stents 108, 118, and 120 shown in FIGS. 35 to 37 are in the molded state shown in FIGS. 23, 29, and 30, respectively, and the outer diameter dimension thereof is φ = 3 mm. 35 (a), 36 (a) and 37 (a) show the velocity distribution in the vicinity of the blood vessel wall surface as vectors, and FIGS. 35 (b), 36 (b) and 37 (b) show blood vessels. The velocity distribution in the vicinity of the wall surface is shown by a surface. 35 to 37 are difficult to see because the analysis results output and displayed as colored images are displayed in gray scale for patent application, but the flow is fast in the dark gray portion in the figure. On the other hand, the light color portion indicates that the flow is slow, and the flow velocity changes stepwise corresponding to the change from the dark gray portion to the light color portion. This analysis was performed using software “ANSYS R14.5” manufactured by ANSYS.

  As a result of comparing FIGS. 35 to 37, compared to FIGS. 36 (a) and 37 (a), FIG. 35 (a) has a large and many dark gray vector lines representing a fast flow as a whole. . 36 (a) and 37 (a), the reason why the number of vector lines is small is that the lines are thin and the flow is slow, so that they are not displayed large as vector lines, or there is almost no flow itself. This is because there seems to be no vector line. On the other hand, compared with FIGS. 36 (b) and 37 (b), 35 (b) shows many lighter portions as a whole. From this, it is shown that the flow velocity of the fluid passing through the vicinity of the strut of the stent 108 of Example 1 is faster than the flow velocity of the fluid passing through the vicinity of the strut of the stent 118 of Example 2 and the stent 120 of the comparative example. . As a result, in the stent 108 of Example 1, the fluid can flow without stagnation at the stent placement position in the lumen compared to the stent 118 of Example 2 and the stent 120 of Comparative Example. In particular, when the stent 108 is indwelled in a blood vessel, the effect of preventing the occurrence of thrombus due to blood retention and turbulence, and restenosis at the stent indwelling position due to the thrombus adhering to the stent is further enhanced. It is suggested that it can be demonstrated.

  The reason for exhibiting such an effect is that the cross section of the strut 102 of the stent 108 of the first embodiment is a substantially inverted triangle, and therefore, the strut 102 ′ having a cross section of the general triangle as in the second embodiment and a rectangular cross section as in the comparative example. Compared to the struts 122, it is presumed that the portion protruding to the inner peripheral side can be made smaller, and the inhibition of the flow of fluid passing through the inside of the stent 108 is suppressed as much as possible.

  In the stent 118 of the second embodiment, the cross-sectional shape of the strut 102 ′ is generally triangular, and the inner peripheral sides of the struts contact with each other relatively early. There is a possibility that the outer diameter reduction effect at the time cannot be fully enjoyed. Further, when the stent 118 is indwelled in the lumen, a portion that protrudes from the lumen wall to the inner peripheral side becomes relatively large, and the protruding portion serves as a barrier for the fluid. There is a possibility that the flow of

  However, the outer peripheral side is tapered in the cross-sectional shape of the strut 102 ', and the stent 118 is positioned so that the tapered tip of the stent 118 bites into the lumen wall, thereby effectively positioning the stent 118 in the lumen. Can be demonstrated. In particular, even in the case where a blood vessel wall is hardened like a calcified lesion and the skeleton of the conventional structure has a rectangular cross section, it is difficult to expand the blood vessel. Since the effect of splitting on the lesion site is exerted, a blood vessel that is difficult to expand with a conventional rectangular cross section can be expanded by employing the stent 118 as in the second embodiment.

  Therefore, depending on the state of the patient and the lesion site, a stent having a substantially triangular cross-sectional shape can be suitably employed. As described above, the stents 108, 110, 112, and 118 of the present invention have excellent technical significance because the stent corresponding to the state of the stenosis site and the site where the stenosis occurs can be manufactured with a large degree of design freedom. It is what you are doing.

  As described above, the problem to be solved by the invention different from the present invention described above (hereinafter referred to as the above invention) depends on the site where the stenosis occurs in the lumen where the stent is placed, the state of the stenosis site, and the like. It is an object of the present invention to provide a stent having a novel structure in which the performance of the stent can be adjusted with a greater degree of design freedom, and the shape corresponding to the lumen of a blood vessel or the like can be realized with a good yield. .

  That is, according to the first aspect of the present invention, in the stent having a tubular structure due to the structure of the skeleton that can be expanded and contracted in the radial direction, and a deformed structure in which the cross-sectional shape of the skeleton changes in the thickness direction, The skeleton is a metal skeleton formed by at least one of electroforming, etching, spraying, and vapor deposition.

  In the stent having the structure according to this aspect, the skeleton has a cross-sectional shape different from a conventional simple rectangular cross-sectional shape, so that the stenosis occurs in the lumen where the stent is placed, the state of the stenosis, or the like. Accordingly, the stent performance and the like can be adjusted efficiently with a large degree of design freedom.

  Further, since the skeleton is formed by at least one of electroforming, etching, thermal spraying, and vapor deposition, the stent has a shape corresponding to the shape of the lumen from the beginning. Therefore, the portion to be excised can be reduced as compared with the stent manufactured by laser processing, and the stent can be manufactured with a good yield.

  A second aspect of the invention is a stent according to the first aspect, wherein the cross-sectional shape of the skeleton is such that the width dimension is increased from the inner peripheral surface toward the outer peripheral surface.

  In the stent having the structure according to the present aspect, the cross-sectional width dimension of the portion exposed to the fluid in the lumen such as blood can be reduced as compared with the stent having the conventional structure having a skeleton having a simple rectangular cross section. . As a result, blood or the like can flow more easily in the placement position of the stent in the lumen of a blood vessel or the like than a stent having a conventional structure, and stagnation or turbulence of blood or the like can be suppressed. As a result, troubles such as formation of thrombus and restenosis of the blood vessel at the indwelling position of the stent due to the attachment of the thrombus to the stent can be effectively avoided.

  In addition, since the cross-sectional width of the skeleton is relatively large in the circumferential direction on the outer peripheral surface of the stent, the pressing force on the inner surface of the lumen such as a blood vessel can be dispersed, resulting in local force concentration. The occurrence of cracks in the lumen wall can be suppressed, and the healing period of the cracks generated in the lumen wall can be shortened. Thereby, for example, restenosis due to enlargement of vascular endothelial cells in a cracked portion of the blood vessel can be effectively suppressed. Even if the vascular endothelial cells are enlarged, a relatively large gap is provided between the skeletons having a reduced cross-sectional width on the inner peripheral surface side of the stent, so that the vascular endothelial cells are separated from the inner peripheral surface of the stent. Further, the enlargement toward the inside is suppressed, and a further inhibitory effect is exerted on the restenosis of the blood vessel.

  Further, in the stent having the structure according to the present aspect, the circumferential width dimension in the skeleton cross section is reduced toward the inner peripheral side, so that when the diameter is reduced by being attached to the delivery catheter, The problem that adjacent skeletons contact each other on the inner peripheral side having a small peripheral length and the amount of diameter reduction is limited is solved. Therefore, while ensuring the cross-sectional area of the skeleton and realizing the required strength and the like, it is possible to improve the delivery performance by setting the size capable of reducing the diameter sufficiently small.

  In the stent according to this aspect, the cross-sectional shape of the skeleton is not particularly limited as long as the width dimension is increased from the inner peripheral surface toward the outer peripheral surface, but it is particularly preferable that the skeleton is an approximately inverted triangle. More preferably, the cross-sectional shape is an approximately inverted isosceles triangle.

  According to a third aspect of the invention, there is provided the stent according to the first or second aspect, wherein in the cross-sectional shape of the skeleton, the depression angles on both sides in the circumferential direction are made larger than the central angle in the arc of the outer circumferential surface. It is what.

  In the stent having the structure according to the present aspect, both side surfaces in the circumferential direction in the skeleton cross section enter a direction approaching each other toward the inner circumferential side rather than the radial line in a state before the diameter reduction. Therefore, even when the diameter is reduced, it is avoided that the skeletons adjacent in the circumferential direction come into contact with each other on the inner circumference side at an early stage and the amount of diameter reduction is limited. As a result, it is possible to realize a stent that can be deformed to a smaller diameter while ensuring the circumferential length of the skeleton on the outer peripheral surface of the stent and avoiding the action of a local pressing force on a blood vessel or the like.

  The fourth aspect of the present invention is the stent according to the second or third aspect, wherein, in the cross-sectional shape of the skeleton, the included angles θ on both sides in the circumferential direction are set to 15 ° ≦ θ ≦ 90 °. It is what.

  In the stent having the structure according to this aspect, the depression angles on both side surfaces in the circumferential direction are relatively small, so that the circumferential dimension in the cross-sectional shape of the skeleton is kept small. As a result, for example, even when the wave number in the circumferential direction of the stent (the number of repeating units in the circumferential direction) is relatively large, an increase in the outer diameter of the entire stent is avoided and stable even when the diameter is reduced. Thus, the diameter can be reduced.

  According to a fifth aspect of the present invention, in the stent according to the first to fourth aspects, the cross-sectional shape of the skeleton changes in the length direction to have a deformed cylindrical shape.

  In the stent having the structure according to this aspect, even when placed in an irregularly shaped lumen such as a blood vessel, a shape corresponding to the lumen is realized with high accuracy, and the burden on the procedure is reduced for the practitioner. The burden on the living body is reduced for the patient. Further, even in the stent itself placed in a shape corresponding to the lumen, distortion and residual stress are reduced, and good shape stability and durability can be realized.

  According to a sixth aspect of the invention, in the stent according to the fifth aspect, a branched portion is provided and the number of the tubular portions is changed in the length direction.

  In the stent structured according to this aspect, a stent that can be easily applied to a bifurcation portion such as a bifurcation in a lumen such as a blood vessel can be realized.

  According to a seventh aspect of the present invention, in the stent according to the fifth or sixth aspect, a deformed cylindrical shape whose radial dimension is changed in the length direction is used.

  In the stent having the structure according to the present aspect, a stent that can be satisfactorily applied to a site where the inner diameter changes in the length direction in a lumen such as a blood vessel can be realized. In addition, the stent of this mode can be combined with the sixth mode, so that at least one tube portion of the stent having a branch portion can have a tapered tube shape or the like.

  According to an eighth aspect of the present invention, in the stent according to any one of the first to seventh aspects, rigidity at at least one end in the axial direction is greater than that of the central portion.

  In a stent having a structure according to this embodiment, only a predetermined portion in the length direction is masked and formed by electroforming, etching, thermal spraying, or vapor deposition, so that the thickness dimension of a specific portion is increased or the material is different. The rigidity can be adjusted. In particular, in the stent of this aspect, the rigidity of the axial end portion that is easily deformed is increased for structural reasons, so that the axial end portion is separated from the lumen while being placed in the lumen. It can also be effectively prevented from causing stenosis.

  That is, the rigidity of the axial end of the stent is improved because, for example, when the axial end of the stent is left in the blood vessel, the blood flow is disturbed and a thrombus is formed. By enlarging and stably indwelling in the blood vessel, restenosis at the stent indwelling position can be effectively prevented.

  A ninth aspect of the invention is the stent according to the eighth aspect, wherein the end portion whose rigidity is increased as compared with the central portion is reduced in rigidity at a terminal portion on the outer side in the axial direction. Is.

  In the stent having the structure according to this aspect, since the rigidity of the end portion at the end of the stent is reduced, the load exerted on the lumen by the end portion of the stent can be suppressed. In addition, since the skeleton is formed of metal, the adjustment of the rigidity at the end portion can be realized by forming only the end portion of the stent with a soft metal, or by reducing the thickness or width. . Preferably, the rigidity of the end portion is set to be substantially the same as or smaller than that of the central portion.

  According to a tenth aspect of the present invention, in the stent according to any one of the first to ninth aspects, the skeleton has a laminated structure of a plurality of types of metals.

  In a stent having a structure according to this aspect, a laminated structure of a plurality of types of metals can be formed by electroforming, thermal spraying, or vapor deposition. For example, by adopting a metal material whose surface layer is more ductile than the core layer, the core layer ensures the strength of the stent while relaxing the stress on the surface when the stent expands or contracts and prevents cracks from occurring It is also possible to do. In addition, by adopting a metal material with a smaller ionization tendency in the surface layer than in the core layer, it is possible to achieve biocompatibility, radiopacity, etc. by the surface layer while ensuring the required strength characteristics in the core layer. It becomes possible. In this embodiment, it is sufficient that at least a part of the skeleton has a stacked structure, and the entire skeleton does not have to have a stacked structure.

  According to an eleventh aspect of the present invention, in the stent according to any one of the first to tenth aspects, the weakened portion partially reduced in strength is at least one of electroforming, thermal spraying, and vapor deposition in the skeleton. It is formed by one.

  In a stent having a structure according to this aspect, by providing a weakened portion in the skeleton, for example, it is divided after placement to obtain a stent shape that conforms to the lumen shape, or for branching by cutting or deforming during placement treatment. Forming the opening by a technique can be easily realized.

  In particular, by forming such fragile parts by electroforming, etching, thermal spraying, and vapor deposition, it does not require a cumbersome operation such as making a separate part from the other part of the skeleton and then fixing the fragile part. It can be provided with dimensional accuracy. However, the main body and the fragile portion of the skeleton need not be formed by the same means among electroforming, thermal spraying, and vapor deposition, and may be formed by different means. In addition, the position and shape of the fragile portion can be arbitrarily set, and the degree of freedom in design can be improved.

  According to a twelfth aspect of the invention, in the stent according to the eleventh aspect, the fragile portion is easily deformed with a smaller cross-sectional area than other portions of the skeleton.

  In the stent having the structure according to the present embodiment, the fragile portion is stably cut by forming the fragile portion thinner than other portions in the skeleton, for example, to further facilitate the bending of the stent. In particular, since the fragile portion is formed by electroforming, thermal spraying, or vapor deposition, for example, it is possible to reduce the thickness of the fragile portion only in the thickness direction, change the material, or the like.

  According to a thirteenth aspect of the invention, in the stent according to any one of the first to twelfth aspects, the skeleton is provided with a medicine containing recess on the surface for containing the medicine.

  In the stent having the structure according to this aspect, since the skeleton is formed by electroforming, thermal spraying, or vapor deposition, a drug containing recess for containing a drug is provided on the surface of the skeleton at the same time as molding, or a convex is provided. It is also possible to provide a medicine housing recess that is provided simultaneously with molding and is relatively concave. And it becomes possible to hold | maintain a chemical | medical agent in a chemical | medical agent accommodation recessed part, and to detain in a lumen | bore by the uneven structure of the surface. In addition, the chemical | medical agent accommodation recessed part in this aspect can be formed in any surface of the internal peripheral surface of a cylindrical peripheral wall, and an outer peripheral surface. Moreover, the medicine accommodating recess in this aspect may be not only a bottomed shape but also a through hole formed by electroforming or the like.

  In addition, the size of the drug containing recess in this aspect is preferably about 10 to 30 μm, which can further reduce the patient's foreign body feeling and adversely affect the strength of the stent. Avoided as much as possible.

  The invention described above is not limited by the specific description of each embodiment, and can be implemented in a manner to which various changes, modifications, improvements, etc. are added based on the knowledge of those skilled in the art. Such embodiments are also included in the scope of the invention as long as they do not depart from the spirit of the invention.

  Furthermore, in the embodiment shown in FIG. 27, the rigidity is increased by making both end portions in the axial direction thick, but in the straight stent in the embodiment shown in FIG. 22, the rigidity is large as both end portions in the axial direction. 27, the thickness of the stent in the aspect shown in FIG. 27 is made substantially constant over the entire length in the axial direction, and a metal having high rigidity is adopted as both end portions in the axial direction. You may enlarge it.

  22, 27, and 28, the generally inverted triangle is exemplified as the shape in which the circumferential width dimension in the cross-sectional shape of the strut 102 gradually decreases from the outer peripheral side toward the inner peripheral side. For example, an inverted trapezoidal shape or a semicircular shape that protrudes toward the inner periphery may be used. However, in the present invention, it is also possible to have a deformed structure in which the circumferential width dimension of the skeleton cross section gradually increases from the outer peripheral side toward the inner peripheral side, as in the stent 118 of Example 2 described above. In addition to the illustrated approximate triangle, the shape may be a trapezoid or a semicircular shape that protrudes toward the outer periphery. This reduces the pressing area of the outer peripheral surface of the stent to the blood vessel in the skeleton and concentrates the pressing force, thereby improving the positioning action of the stent on the blood vessel and Misalignment can also be suppressed. In addition, since the pressing force is concentrated on the blood vessel wall, not only can an effective expansion action be exerted on a hardened blood vessel such as a calcified lesion, but also a non-hardened blood vessel However, it is possible to expand to a desired dimension with a smaller expansion force.

  Further, in the present invention, a deformed structure in which the circumferential width dimension of the skeleton cross section is increased at the intermediate portion in the stent radial direction and gradually decreases toward both the outer peripheral side and the inner peripheral side, that is, for example, a rhombic cross section or a circular shape. A cross section or an elliptical cross section is also possible. This makes it possible to concentrate the pressing force on the blood vessel on the outer peripheral surface of the skeleton while suppressing mutual interference in the circumferential direction at the inner peripheral ends of the skeletons adjacent to each other in the circumferential direction, which tends to be an obstacle when the stent is reduced in diameter. Thus, it is possible to improve positioning performance and blood vessel expansion performance.

  The stent having the structure according to the above-described aspect of the present invention is also applied to a flow diverter for treating a cerebral aneurysm. The flow diverter is, for example, a low-porosity blood flow bypass device improved for endovascular treatment of cerebral aneurysms. In addition, the said invention is applied also to the stent main body except the cover in covered stents, such as a flow diverter and a stent graft. The stent having the structure according to the above aspect of the present invention is also applied to the tip portion of the stent retriever system. The stent retriever system is, for example, a reticular cylindrical thrombectomy device for efficiently squeezing and removing a thrombus with a net.

10, 50, 60, 62, 68: stent, 12, 52: annular portion (skeleton), 14, 54: link portion (skeleton), 16, 22, 28, 38: strut (skeleton), 18, 24, 30 : Core layer, 20, 26: Core decomposition control layer, 40: Contrast layer, 56: Self-expanding region, 58: Hyperdeformation region

Claims (6)

A stent having a cylindrical skeleton that can be expanded and contracted in the radial direction,
The skeleton includes a self-expanding region that deforms into a predetermined shape by superelasticity, and a portion of the skeleton that is off the self-expanding region in the axial direction can be deformed to a greater extent than the self-expanding region. A stent characterized by being a deformation region.   The stent according to claim 1, wherein at least one end in the axial direction of the skeleton is the overdeformed region.   The stent according to claim 1 or 2, wherein the over-deformed region is capable of expanding and deforming to a larger diameter than the self-expanding region.   The stent according to any one of claims 1 to 3, wherein the over-deformed region is expanded by a balloon so as to be deformed more than the self-expanding region.   The stent according to claim 4, wherein a gap in the peripheral wall portion of the over-deformed region is expanded by the balloon so as to be deformable more than the gap in the self-expanding region.   The stent according to any one of claims 1 to 5, wherein the self-expanding region and the overdeformed region are formed by at least one of spraying, vapor deposition, etching, and electroforming.