JP2012196499A - Endoprosthesis - Google Patents

Abstract

[PROBLEMS] To maintain the followability and flexibility to the tubular organ shape, ease of diameter reduction, improve the expansion / support function of the tubular organ and the transportability in the tubular organ, and require a special configuration and means. And can be applied to a site having a side branch of a tubular organ.
A support structure having one layer formed of a deformable material and having a mesh shape of a column, and a support structure having another layer having a mesh shape of a column formed of a deformable material. The two layers are joined and fixed in a part of the region, the struts of the struts of both layers are mutually different in shape, and the struts in each support structure are viewed from the outside. In the mesh shape, there are non-overlapping portions, and the struts can be freely deformed from each other in a region other than a partial region where the support structures of the respective layers are joined. The support structure may have three or more layers, or may have a combined shape in which the struts are easily deformed in the circumferential direction in the region between the bonding regions.
[Selection] Figure 6

Description

  The present invention relates to an endoluminal endoprosthesis having a support structure.

  There is a disease in which tubular organs such as blood vessels in the body cause stenosis. These diseases sometimes have a significant impact on life. As an example, when a stenosis occurs in a coronary artery, the blood flow to the myocardium decreases and the function of the heart is reduced. This threatens life. As a device for treating such a disease, there is a device called a stent. In general, a stent is formed by rounding a planar structure having a mesh shape as shown in the developed view in FIG. 1A and partially in the enlarged view in FIG. Has a cylindrical structure with an opening. Here, the mesh shape is simply shown in (c). The unit structure in FIG. 1B is formed by connecting the cell 2 and the link 3 (or connector), and the cell 2 plays a role of expanding the tubular organ and deforms when the diameter is reduced or expanded in the radial direction. It is divided into a cell bent portion 4 and a non-deformed portion 5 that hardly deforms. In many cases, the non-deformable portion 5 has a substantially linear shape. FIG. 1A shows a shape in which the unit structure of FIG. Materials for stents include plastically deformable metals such as stainless steel, bent-shaped cells and metals with properties such as shape memory and superelasticity (for example, NiTi alloys), metals with superplasticity and melting characteristics in vivo, Plastics that exhibit degradability are used. Most used are stents made of a plastically deformable metal material such as stainless steel.

  Since the stent is made of a hollow pipe or the like, it has a shape close to a perfect circle before use, but when expanded, only the cell bent portion 4 is deformed. For example, when a stainless stent having a diameter before expansion of 1.0 mm to 1.5 mm is expanded to a diameter of about 3.0 mm, a strain of about 30% is generated. The distortion is very concentrated especially on the inner side of the cell bent portion.

  The stent is attached to a delivery device called a balloon catheter with a radius reduced so that it can be easily placed in a tubular organ in a living body outside the body. If the radius of the stent can be reduced when attached to the balloon catheter, it can be very easily transported to the lesion when inserted into the body or after insertion.

  A stent attached to the balloon catheter is inserted into a blood vessel or the like with a small part of the living body incised, and is then transported to the lesion site. When the stent is delivered to the lesion site, the tip of the balloon catheter is expanded there. A stent is attached to the distal end portion of the balloon catheter, but the portion to which the stent is attached has a balloon shape and can be expanded. The stent is also expanded in the body by the expansion of the balloon catheter. When the stent is a plastic material, the stent is expanded to cause plastic deformation and the deformation is retained permanently. When the balloon catheter is removed after the stent is expanded, only the plastically deformed stent is left in the expanded state of the lesion site where the stenosis has occurred.

  Various structures have been proposed for stents. Many functions are required for stents, but the basic required functions are radial deformability, radial rigidity to support the tubular organ when expanded, and the long axis direction that can follow the complex shape of the tubular organ The flexibility. In many cases, the stent is basically constituted by repeating the same shape in the circumferential direction and the long axis direction.

  In Patent Document 1, as a typical example of such a structure, a stent composed of a portion called a “cell” that expands and supports a tubular organ and a “link” that gives the stent flexibility in the longitudinal direction. Are listed. Such a stent is called a closed cell structure, and the link has an S-shape or N-shape.

  Patent Document 2 describes a structure in which “cells” that expand and support tubular organs are connected by struts called “connectors” that are substantially parallel to and substantially parallel to the long axis direction of the stent. This is called an open cell structure. In addition to this, a stent in which a wire is formed in a coil shape, or a stent having a strut called a spine substantially parallel to the longitudinal direction of the stent, and a strut arranged perpendicularly to the strut, that is, in the circumferential direction (special table) No. 8-507243) and the like, but the former two are the mainstream in practice.

  The closed cell structure and the open cell structure are characterized by the difference in the size of the repeating structural unit in addition to the above-described characteristics. In general, the closed cell structure has a smaller size of the repeating structural unit.

  The closed cell structure and the open cell structure have advantages and disadvantages as described in Non-Patent Document 1. For example, the closed cell structure is characterized by little change in shape when the stent is bent, and can expand and support the tubular organ with a uniform stress distribution, but it is difficult to use in a portion where the tubular organ is branched. On the other hand, in an open cell structure, although highly flexible, a portion of the stent may be unexpectedly deformed excessively when bent, thereby imparting a non-uniform stress distribution to the tubular organ. However, it is suitable for use in a portion where the tubular organ is branched.

  In general, the conventional stent has a structure in which cells and links (or connectors) are alternately arranged in a row when viewed in the long axis direction, and the link (or connector) portion has almost no expansion and support functions for tubular organs. There is a problem that cannot be expected. This is particularly noticeable in the closed cell structure, and is also noticeable when the open cell structure is expanded.

  By the way, the stent is required to have followability to the tubular organ shape. This followability means that the stent expands into a tubular organ that meanders in the long axis direction and follows the tube faithfully after placement. At the same time, it is desirable to follow the radial cross-sectional shape of the tubular organ, that is, to expand and support the tubular organ into a circular shape.

Insufficient followability of the stent to the shape of the tubular organ causes a problem that the expandability of the tubular organ becomes non-uniform in the long axis direction when the stent is placed in the tubular organ, and in the tubular organ. It develops into the problem of non-uniform stress distribution and damage to the tubular organ at the stress concentration site and the resulting restenosis. Conventional stents are not always satisfactory in terms of the ability to follow the shape of the tubular organ. FIGS. 2 (a) and 2 (b) show the situation when the stent is bent, as shown in FIG. When a stent having a different structure is bent, the link (or connector) portion that gives flexibility is deformed, and the cell portion is not deformed. Therefore, the bent shape is usually a polygonal shape as shown in (b). This tendency is more remarkable in the open cell structure. Due to the polygonal shape, a strong contact stress acts between the stent and the tubular organ at these apex portions, and there is a risk of damaging the tubular organ.

  In order to alleviate this, it is conceivable that a large number of links (or connectors) are arranged in the major axis direction to realize a smooth shape when bent. However, if a large number of links (or connectors) are arranged in a stent having the same overall length, the length in the major axis direction of one row of cells is reduced accordingly. When a certain strain or more is applied to the material, the material cracks and breaks. Therefore, there is a limit to the change in the angle of the cell bent part before and after expansion. There is a limit to the deformation of such individual cells, and as the length in the long axis direction of each cell decreases by increasing the number of cells in the long axis direction, the amount of expansion deformation of each cell decreases accordingly. . That is, if the length of the long axis direction of the cell is short, the radius of the stent that can be reached at the time of expansion becomes small. This means that the basic requirement for a therapeutic device that the stenotic part of the tubular organ must be expanded larger cannot be met. Therefore, it cannot be said that arranging a large number of links (or connectors) in the major axis direction leads to overcoming the technical problem as described above.

  Further, the stent has expandability due to its own elasticity, and the cross-sectional shape of the expanded stent is generally polygonal. In order to adapt this polygonal shape to the inner surface of the tubular organ as much as possible, the number of cells in the circumferential direction is increased, but there is a similar problem in this case as well.

  In addition, as a configuration of the stent, there is a multi-layer structure in which two or more layers are coaxially stacked, and Patent Document 3 discloses an artificial internal organ in which two or more layers including a stent layer are coaxially stacked. As described above, a stent graft in which an artificial blood vessel is combined with a stent is disclosed. This is because a flexible material layer made of polytetrafluoroethylene or the like corresponding to an artificial blood vessel is fixed by the clamping force of the inner-outer stent, and the inner-outer stent is put into the body of the flexible material layer. As a means for preventing damage during insertion. This multi-layer structure is intended to have a structure in which a flexible material layer corresponding to an artificial blood vessel is interposed. In terms of transportation in a tubular organ, expansion / support of a tubular organ, etc., a single-layer support structure Has almost the same problems as

  Patent Documents 4 and 5 propose a stent composed of an inner layer and an outer layer. This is made by processing two different types of materials such as a shape memory alloy superelastic material and malleable material (elastic plastic material) such as stainless steel into a single tube, and then processing it into a stent shape. However, the stent is formed so that the material composition of the struts exhibits a layered structure in the radial direction, and the stent function is intended to be improved by the material properties of the struts provided with the layered structure. This multi-layer structure is a multi-layer structure in which different materials are integrated. The shape and function of the stent is not different from that of a single layer. In terms of support and the like, the problems that appear in a single-layer support structure are almost intact.

  Patent Document 6 describes a multi-layer stent, which has a series of segments having a distal end portion that becomes a peak portion and a proximal end portion that becomes a valley portion, and an outer layer and an inner layer are connected at the valley portion. It has become. This structure is intended to increase the expansion rate, and is multi-layered in the non-expanded state, but is a single layer in the expanded state (used state).

  Patent Document 7 describes a stent having a multi-layer tubular structure that can be expanded in the radial direction. This is formed by forming a concave portion on one of two metal sheets, surface-treating, and performing an overlapping meshing forming process. , Wound into a tube to form a stent structure, or formed as a metal tube having a different diameter and slid into the other, and the two layers have different mechanical properties Yes.

  In the stent having such a configuration, the radial resistance to collapse and the expandability are increased. However, when the sandwich layer is used, the yield strength after rolling is larger than that of a single layer having the same thickness. By using. In that sense, it is structured as a single composite layer and solves the problem of a single-layered stent by taking advantage of the characteristics of multiple layers. No.

  In addition, it may be necessary to place the stent in a tubular organ part with side branches, and in order to enable treatment with the stent in such a case, the stent is placed. It is conceivable to introduce a balloon catheter from the side of the previously placed stent into the branch side branch by reducing the number of stent struts in the stent portion corresponding to the side branch branch portion (side branch base portion) and increasing the gap.

  FIGS. 3A to 3C show a procedure for treating a stenotic site of a blood vessel having a side branch as a tubular organ. First, one stent is placed in the main blood vessel as shown in (a), and then another stent is mounted on the side branch portion blocked by the stent as shown in (b). Guide the balloon catheter. At that time, the side surface of the stent placed in the main pipe is forcibly passed. Then, the side surface of the stent placed in the main pipe is forcibly expanded, and the stent is placed in the side branch portion as shown in (c). At this time, the side surface of the stent placed in the main pipe has a very large hole. In other words, a stent that has room for expansion on the side surface (cylindrical surface) of the stent is suitable for treatment in a portion with a side branch, and it is said that the open cell structure is excellent in approaching the side branch for this purpose. Yes.

  However, there are two difficulties in realizing this. First, when a stent is placed in a side branch, a stenosis usually occurs in the branch part of the side branch, and an area where the stent strut is desired to be reduced and the stenosis part is expanded to facilitate the approach of the balloon catheter to the side branch. Areas that require sufficient radial rigidity to be in close proximity. Second, because treatment is performed under fluoroscopy, even if the number of stent struts in a specific location is reduced, the location is reliably positioned on the side branch (the long axis position and the circumferential angle). It is impossible to deny the possibility that the site where the struts of the stent are reduced is misplaced in the stenosis region of the blood vessel and the stenosis cannot be sufficiently expanded.

  Patent Document 8 and Patent Document 9 disclose a stent applied to a portion having a side branch and a dedicated balloon catheter. This balloon catheter is provided with a special side branch discriminating device and can specify the position of the side branch in the long axis direction and the angle in the circumferential direction. In order to easily introduce the balloon catheter into the stent and the side branch, it is structured to easily open one place outward. However, in order to enhance the therapeutic effect of the bifurcation as described above, there is a problem that it is necessary to prepare a special stent or a special delivery device.

U.S. Pat. No. 3,236,623 Special table 2001-501494 gazette JP-A-10-314313 JP 2002-537072 gazette JP-A-11-332998 JP 2005-515002 A JP 2005-535422 A Special table 2003-532447 gazette Special table 2003-532446 gazette Yamaguchi et al. “Drug-Eluting Stent” (Medical School, 2004)

  As described above, in the prior art endoprosthesis (stent), the followability and flexibility of the tubular organ shape, the ease of diameter reduction are maintained, and the expansion / support function of the tubular organ, There are structural limitations to improve transportability, and it cannot be advantageously applied to the treatment of locations with side branches, or requires special stents or special delivery devices. there were. Therefore, it is possible to maintain the followability and flexibility of the tubular organ shape as a structure of the endoprosthesis, ease of diameter reduction, and improve the expansion / support function of the tubular organ and the transportability in the tubular organ. There has also been a need for an endoprosthesis that can be applied to the treatment of a site having a side branch without requiring a special delivery device or the like.

The present invention has been made to solve the aforementioned problems, and the endoprosthesis according to the present invention is:
A number of struts are arranged in the form of a mesh in the circumferential direction of the cylindrical body, and a plurality of struts are arranged in the circumferential direction of the cylindrical body with respect to a single-layer supporting structure formed of a deformable material. Inserting a support structure forming another layer made of a deformable material so as to have a diameter of a size to be inserted into the support structure forming the one layer by combining them so as to form a mesh shape of The support structure forming the one layer and the support structure forming the other layer are joined and fixed in a partial region in the long axis direction, and the support structure forming the one layer is In a region other than a part of the region where the support structure forming another layer is joined, the support columns forming the one layer and the support structure forming the other layer are freely deformed to each other. Possible, the support of the strut in the one-layer support structure The shape of the support and the mesh structure of the support in the other layer are different from each other, so that the entire structure is viewed from the outside and the support mesh in the support structure forming the adjacent layer does not overlap. The part is made to exist.

  The support structure forming the other layer is inserted into the support structure forming the one layer, and the support structure forming another layer of a cylindrical shape having a smaller diameter is sequentially inserted into the support structure forming the other layer. A support structure that forms a plurality of layers by being inserted inside, and a support structure that forms adjacent layers is joined and fixed in a partial region in the major axis direction to form an entire layer. The struts in the support structure forming the adjacent layer in a region other than the partial region where the support structure forming the adjacent layer is bonded can be freely deformed to each other. Good.

  The structure of the struts of the support structure forming the plurality of layers is formed by alternately combining cells that are elements of the struts that expand and maintain the tubular organ, and links or connectors that impart flexibility. Also good.

  In each layer of the support structure forming the plurality of layers, bonding between adjacent layers is performed in at least both end side regions in the axial direction of the entire cylindrical endoprosthesis, and an intermediate region between the regions where the layers are bonded is formed. The mesh structure of the struts in at least a partial region of the part is mainly composed of strut elements that are easily deformed in the circumferential direction of the support structure, and deformation of the tubular organ by deformation of the struts in at least a partial region of the intermediate part. When an endoprosthesis is applied to a site having a side branch, another endoprosthesis may be inserted from the endoprosthesis toward the side branch.

  The mesh shape of the struts in at least a partial region in the middle part of the region where the layers are bonded in the support structure forming at least one of the layers forming the plurality of layers in the circumferential direction of the support structure The support structure, which is mainly composed of easily deformable strut elements and forms a layer other than the at least one layer forming the plurality of layers, has a length corresponding to a part of the support structure forming the at least one layer. Each layer may be overlapped and bonded to form a structure in which a plurality of cylindrical support structures are stacked and bonded over the entire length of the endoprosthesis.

  The support element that is easily deformable in the circumferential direction of the support structure may have a link or a connector as an element of the support structure that provides flexibility, and is elongated in the long axis direction.

  In the present invention, an endoprosthesis is formed by a multi-layer support structure, and the support structures forming adjacent layers are joined in a part of the region, and each support structure is viewed from the outside. In the area other than the part of the area where the adjacent support structures are joined, the struts can be freely deformed to each other in such a manner that there is a portion that does not overlap in the mesh shape formed by the struts in The ability to expand and support tubular organs while maintaining followability and flexibility of tubular organ shapes and ease of diameter reduction compared to endoprostheses formed as a single layer or as an integral structure. The transportability in the tubular organ can be improved.

  In addition, in at least a partial region of the central portion of the endoprosthesis, at least a part of the mesh structure of the support column is mainly composed of elements of the support column that easily deform in the circumferential direction of the support structure. When an endoprosthesis is applied to a part having an internal prosthesis, another endoprosthesis can be inserted from the endoprosthesis toward the side branch, and a part having a side branch easily using a structure applicable to a normal tubular organ Can be applied without requiring a special configuration or means.

  An endoprosthesis according to the present invention has a cylindrical support structure formed of a deformable material having a mesh shape arranged in a cylindrical peripheral surface in combination with a number of support columns including bent portions, coaxially. It is configured by stacking and supporting pillars in the support structure of adjacent layers through a joint portion. A number of struts in each layer may have a stent structure in which cells and links in a stent are repeatedly arranged in a cylindrical peripheral surface as shown in FIG. Is a form having a portion that retains an expanded state and a portion that imparts flexibility when a tubular endoprosthesis comprising a multi-layer support structure is formed due to its shape and arrangement. Support structure materials include plastically deformable metals such as stainless steel, bent-shaped cells and metals with properties such as shape memory and superelasticity (for example, NiTi alloys), metals with superplasticity and melting characteristics in vivo Plastics that exhibit biodegradability are used.

  In the present invention, a cylindrical support structure having a plurality of layers having the material and configuration used as such a stent is coaxially overlapped, and cells and links in the support structures of adjacent layers are joined. This provides features not available with single layer stents.

[Embodiment 1]
FIG. 4A shows two cylindrical support structures A and B. Each of the support structures A and B is composed of a number of support columns arranged so as to form a network structure as shown in FIG. The planar structure is rounded into a cylindrical shape, the inner diameter of the support structure A is equal to the outer diameter of the support structure B, and the support structure B can be inserted into the support structure A. If the lengths of the support structure A and the support structure B are made equal, the ends of the support structure A and the support structure B are aligned after insertion, but the lengths of the both are not necessarily equal. Also good. In the present invention, an endoprosthesis is formed by inserting the support structure B into the support structure A as shown in FIG. 4 (b), and joining and integrating necessary portions by welding or the like.

  Support structure A (outer layer) and support structure B (inner layer) may each have the shape and arrangement of struts that act independently as stents, or they do not act as stents, but they are combined. And may act as a stent in a joined state. Further, the mesh shape and arrangement of the struts of the outer layer and the inner layer may be the same except that the diameters are different, and the shapes and arrangements of both may be different. When the shape and arrangement of the struts are the same, the outer struts and the inner struts are joined in a state shifted in the circumferential direction or the major axis direction so as not to overlap.

  The support structure that forms the outer layer and the support structure that forms the inner layer are joined to each other in a necessary region in a portion where the struts of both layers overlap. For example, as shown in FIG. 5 (a) when viewed from the side, the outer layer and the inner layer of the support structure are separated from each other in four regions a, b, c, and d in the longitudinal direction of the support structure. Bonding is performed at the overlapping portion. In this manner, in the region between the regions a, b, c, and d, the struts of the outer layer and the inner layer can be freely deformed without being joined. Even in the regions a, b, c, and d, if, for example, every two or two of the overlapping portions of the struts are joined in the circumferential direction, the restriction on the deformation in the radial direction can be reduced. it can. In this way, the outer layer and the inner layer are joined to each other in a part of the region so that the two layers are not relatively displaced, and the struts of both layers can be deformed to each other. FIG. 5 (b) shows a joint location at a portion where the struts of both layers overlap. As a joining method, for example, pressure can be applied to the joint location with an electrode and resistance welding can be used. FIG. 5C shows a cross section at the joint, and a nugget is formed at the joint. Other joining methods include resistance welding, thermocompression bonding, and ultrasonic welding. Also, a concave portion is formed on one side of the joining portion, and a convex portion that is closely fitted to this is formed on the other side. Alternatively, the convex portion may be press-fitted into the concave portion and joining may be performed. As a bonding method, it is preferable to use a method that does not generate eluate or precipitate.

  FIGS. 6A to 6C show the support structure having the outer layer and the support structure having the inner layer having different mesh shapes. The mesh shape of one layer shown in FIG. 6 (a) is different from the mesh shape of the other layers shown in FIG. 6 (b). When the support structure forming the inner layer is inserted into the support structure forming the outer layer having the mesh shape of the different columns as described above, the mesh shapes of the columns of both layers have a portion that does not overlap as shown in FIG. . When the support structure forming the outer layer and the support structure forming the inner layer are different in the mesh shape of the struts, the shape can be various. In the prosthetic internal organ of the present invention, a plurality of layers are formed. The support structure to be formed is joined in a part of the area, and the condition that the struts in the unjoined area of both layers can be freely deformed to each other is necessary. However, this condition should not be violated.

  The support structure that constitutes the endoprosthesis can be formed into a mesh structure of pillars by laser processing or the like, but it is formed into a mesh structure in the state of a thin plate, and then processed into a cylindrical shape, It is good also as a support structure by joining so that a cross section may be in the closed state. An endoprosthesis is configured by forming a support structure having a plurality of layers having different diameters, inserting a support structure having a small diameter into the support structure having a large diameter, and joining the portions appropriately. The support structure may remain substantially C-shaped without having a closed cross-sectional shape. An endoprosthesis can be formed by superimposing substantially C-shaped support structures instead of a closed cross-sectional shape and joining them in the radial direction. Further, a plan development view of a desired support structure is formed on a flat thin plate, and a plurality of layers are laminated in the flat state, the layers are joined, and then the layered flat plate is processed into a cylindrical shape. An endoprosthesis may be formed by joining the parts.

  As a material for forming the support structure constituting the endoprosthesis, a biodegradable polymer may be used in addition to metal materials such as stainless steel, cobalt chromium, titanium alloy, nickel titanium alloy, and magnesium alloy. Since endoprostheses are used to expand and support tubular organs, radial rigidity is important, but in order to increase radial rigidity, the Young's modulus and yield stress of the material used are high. Is desirable. On the other hand, when the endoprosthesis is reduced in diameter and expanded, a large amount of distortion occurs in the cell bent portion. From this, it is desirable to use a material having a large breaking strain. Endoprosthesis using biodegradable polymer is considered to be highly safe because it is decomposed in vivo after a certain period of time and there is no risk of leaving foreign matter in the body for a long time. Since the degree of mechanical properties such as Young's modulus is lower than that, it is necessary to make the struts thicker in order to ensure radial rigidity. The material of the support structure that constitutes the endoprosthesis should be appropriately selected according to the purpose of use and the form in consideration of the characteristics of such a material.

  Regarding the dimensions of the support in the support structure that constitutes the prosthetic internal organ, it is known that the thicker the support, the higher the restenosis rate and the therapeutic effect is inferior. However, when the endoprosthesis of the present invention is formed by superimposing support structures, and the endoprosthesis is adapted for the treatment of coronary arteries, the thickness of the struts in each layer is It is preferable to form a thinner support column (0.05 mm to 0.20 mm) in the case of a single layer and to superimpose them. At that time, the strut thickness of each layer is preferably about 0.01 mm to 0.05 mm, and the support structure having these struts is overlapped, and the thickness of the endoprosthesis is 0.05 mm equivalent to that of a single layer for coronary arteries. It is preferable to form it to ˜0.20 mm.

  In the case of a single layer for coronal motion, the preferred strut thickness is about 0.05 mm to 0.20 mm. However, as in the present invention, a plurality of support structures are overlapped so that the struts do not overlap. In the organ, the area covering the blood vessel is dramatically increased as compared with that of a single layer, and the proliferated cells that occur during restenosis have an effect of suppressing the invasion into the blood vessel lumen. Therefore, even if it is thinner than 0.05 mm to 0.20 mm which is a preferable strut thickness for a single layer for coronary artery, the same therapeutic effect can be expected. Specifically, the thickness of the endoprosthesis is preferably about 0.01 mm to 0.20 mm.

  As for the width of the strut, in the case of a single layer for coronary arteries, the preferable strut width is about 0.02 to 0.15 mm. However, in the prosthetic internal organ of the present invention consisting of a plurality of layers, Even if it forms so that sufficient rigidity in the radial direction can be obtained. Accordingly, the preferred strut width of an endoprosthesis having a multi-layered support structure of the present invention is 0.001 mm to 0.20 mm. When the prosthetic internal organ of the present invention is applied to the treatment of other parts, it is preferable to use a support structure having a column width comparable to that of a single layer used in that part.

  In the prosthetic internal organ of the present invention, the support structure forming the inner layer is inserted into the support structure forming the outer layer, and the struts overlapping in a part of the region are joined. In order to maintain the flexibility in the radial direction to expand the structure, it is required that the struts of both layers can be freely deformed outside the joined area. For this reason, in the case where the strut mesh shape is composed of a cell that acts so as to expand the tubular organ and a link or connector that connects the cells, the joint portion is provided in a portion of the link or connector other than the cell in the radial direction. Stiffness is maintained.

  In addition, since the struts of the outer layer and the inner layer can be freely deformed outside the joined region, the joint location between the outer layer and the inner layer is limited. Therefore, it is preferable to increase the joint strength at the joint location provided, and the column portion of the joint portion is not a monotonous column, and only that portion has an oval or circular surface in which the area of the columns of both layers is widened. You may make it be a simple shape.

  In this way, the outer strut and the inner strut do not overlap as a whole when viewed from the outside, regardless of the shape and arrangement of the struts of the outer layer and the inner layer being the same or different. Inner struts will be interposed in the space between the two. Thereby, in the expanded state of the endoprosthesis in which the outer layer and the inner layer are integrated, the action of reinforcing the pressing and holding of the inner surface of the tubular organ by interposing the inner strut in the space between the outer struts. Is obtained.

  In terms of giving the action of pressing and holding the inner surface of the tubular organ, it may be a single layer formed with struts corresponding to the shape of the outer layer and inner layer combined, but in that case the strut network structure is fine Inevitably, the deformability and flexibility of the endoprosthesis are reduced. In the present invention, the struts of the outer layer and the inner layer can be deformed freely without reducing the mesh structure of the struts of each layer by sharing the action of pressing and holding the inner surface of the tubular organ with the struts of the plurality of layers. By joining the outer layer and the inner layer in this manner, an effect that cannot be achieved by a single layer in the press-holding and deformability of the endoprosthesis can be obtained. Thus, in order to allow the outer strut and the inner strut to be freely deformed, the outer layer and the inner layer are not joined to each other on the entire surface, but the struts can be freely deformed at necessary places. Shall.

  The mesh shape of the columns in one support structure is shown as an example of a uniform shape composed of cells and links. For example, as shown in FIG. In this case, the mesh shape of the support may be different between the joining region and the other region. The strut has a radial rigidity that expands the tubular organ as an artificial internal organ that combines the mesh structure of the strut in the support structure that forms the outer layer and the support structure that forms the inner layer and joins in a partial region, The mesh shape of the strut can be designed in various forms so that it can be deformed in conformity with the shape of the tubular organ. The joining regions are not limited to four locations a, b, c, and d, but may be increased, and only a and d on both sides may be provided as long as the joining strength is satisfied.

  FIG. 7 shows an example of the mesh shape of such a support. (A) is a support structure forming an inner layer, and (b) is a support structure forming an outer layer, and the mesh shape of the support is viewed from the side. The state is shown exaggerated in the radial direction with respect to the length direction. Both the inner layer and the outer layer have joints in the regions e and g on both ends (circles), and the struts of the inner layer and the outer layer are not significantly displaced from each other in this part. In contrast, in the intermediate region f, the inner layer and the outer layer are not joined, and the inner layer and the outer layer can be freely displaced from each other. Further, the mesh shape in the intermediate region f is different from the mesh shape in the regions e and g on both ends, and is shifted in the circumferential direction with the inner layer inserted into the outer layer.

  In the above description, an example of an artificial internal organ using a two-layer support structure in which the support structure forming the inner layer is inserted into the support structure forming the outer layer and joined in a part of the region is shown. It is also possible to insert a support structure into an artificial internal organ with a support structure of three or more layers. A prosthetic internal organ is configured by sequentially inserting support structures having cylindrical shapes with different diameters and having a mesh structure of struts, and joining in some regions between the support structures forming adjacent layers. The area of the support structure that forms each layer and the shape of the column in the support structure that forms each layer should be such that there is a non-overlapping part of the support structure that forms each layer when viewed from the outside. It is the same as in the case of the two-layer support structure that the struts can be freely deformed in this area and the rigidity in the radial direction is maintained.

  Such an artificial internal organ composed of a multilayer support structure can be suitably applied to a site having a side branch. FIG. 8 is a diagram showing a part of the mesh shape of the support structure for explaining the operation of such an endoprosthesis. The mesh structure of the support structure struts forming the outer layer composed of the Celtlink is shown by a solid line. The mesh shape of the support column of the support structure forming the inner layer composed of cells and links is shown by dotted lines. In the figure, the outer layer and the inner layer are joined in the regions h and j on both sides (not necessarily the axial ends in the overall configuration), and the outer layer and the inner layer are joined in the intermediate region i. The support columns can be freely deformed. The mesh shape of the outer layer and the inner layer is the same shape except that the position of the link portion is shifted, but can also be different from each other.

  In the intermediate region i, the support column can be freely deformed in the circumferential direction, and can be easily spread as shown by a radial arrow in the central portion of the figure. That is, if the endoprosthesis is placed so that the region where the column is easily deformed becomes the position of the side branch of the tubular organ, another endoprosthesis can be mounted as shown in FIGS. It is easy to introduce the mounted balloon catheter into the side branch. In order to make it easier for the struts to deform laterally in the middle part of the joined area, it is conceivable to introduce a balloon catheter with another endoprosthesis mounted on the part between the joined areas, especially in the side branch. There may be no cell as an element of the column in the region, and a link or connector that is easily deformed in the circumferential direction may be arranged and configured with a longer length. That is, it is preferable to appropriately select and set the shape of the mesh shape of the support so as to give such characteristics of the endoprosthesis in the portion between the joined regions.

[Embodiment 2]
FIGS. 9A to 9D are diagrams showing examples of other forms of endoprostheses for application to locations having side branches, in which the support structure A in FIG. It has a mesh shape of struts combined with links, and there is no cell in the central part, and it is a part of the structure only of the link, and this part is easily deformed in the radial direction or the circumferential direction. The support structure B shown in (b) has a diameter that is superimposed on the outside of the support structure, and the support structure C has a diameter that is superimposed on the inside. Are about half the length of the support structure A.

  FIG. 9C shows an endoprosthesis formed by inserting the support structure A into the support structure B on the left side of the figure and inserting the support structure C into the right side of the support structure A. FIG. 9D shows the relationship between the support structures A, B, and C in a cross section in the major axis direction. In the central portion of the support structure A, the mesh shape of the support column is only a link or a connector, and is easily deformed in the circumferential direction. The portions of the support structures B and C that overlap with this portion have a mesh shape that is easily deformed. Thus, after superimposing support structure A, B, C, it joins between the layers which adjoin in appropriate area | regions other than a center part. The support structures A, B, and C have a structure in which cells and links are combined, and have a portion in which the mesh structure of the columns in the support structures (A, B, A, and C) forming the overlapping layers do not overlap. In addition, as described in the first embodiment, the support columns in the support structure can be freely deformed except in the joined region. In this way, the endoprosthesis in which the support structures A, B, and C are overlapped has a cell overlapped in any region in the long axis direction, and the radial direction is uniform in the long axis direction. The rigidity of is maintained. When such an endoprosthesis is placed at a treatment site of a tubular organ, in order to minimize the disturbance of fluid flow in the tubular organ, the end portion in the longitudinal direction on which the inner support structure C is overlapped is provided. It is good to place it so that it may be located in the upstream of the fluid which flows into the treatment site | part in the said tubular organ.

  In the situation where it is placed in a tubular organ having a side branch, it is easy to introduce a balloon catheter into the side branch using the endoprosthesis shown in FIG. In the endoprosthesis shown in FIG. 9, there is no cell in the middle portion between the joint regions in the support structure A, and a long link in the major axis direction is arranged, so that the mesh shape of the column is in the circumferential direction. It is easy to expand. As described above, since the support structure is easily expanded outward in the intermediate portion between the joint regions in the endoprosthesis in FIG. 9, the side branch can be easily approached with a balloon catheter or the like as shown in FIG. . As shown in FIG. 10, the region where there is no cell and the link is long in the central portion (intermediate portion of the joint) of the support structure B is easily deformed in the circumferential direction, and this region is used for the side branch. The endoprosthesis is pushed and spread at the tip of the mounted balloon catheter, and inserted into the side branch so as to push away the end side of the outer support structure A. Such an endoprosthesis allows the side branch to be approached with a balloon catheter or the like even if the indwelling positioning accuracy is somewhat inferior, and it is possible to treat a site having a side branch without using a special delivery device or endoprosthesis. Endoprostheses can be formed that are well suited to the treatment of sites with side branches while being able to treat these sites.

  In the support structure that forms the inner layer of the endoprosthesis, there is a post portion that is not joined to the support structure that forms the outer layer. The possibility of this strut popping out during the transporting operation, expansion, or detention of the tubular organ can be suppressed.

It is a figure which shows a general stent, (a) The figure which showed the mesh shape by the plane, (b) The figure which expanded the mesh shape partially, (c) The figure which showed the stent made into cylindrical shape roughly . (A) It is a figure which shows roughly the condition before a stent bends, and (b) shows the condition in which a stent is bent roughly. (A)-(c): It is a figure which shows roughly the procedure which applies a stent to the site | part which has the side branch of a tubular organ. (A), (b): It is a figure which shows the structural form which has a two-layer support structure about the endoprosthesis by this invention. (A) The example of the area | region which joins the interlayer of the support structure which makes a several layer is shown, (b) The example of the joining method of a support | pillar is shown, (c) It is a figure which shows the cross section of the junction part in (b). . 2 shows an example in which two layers of support structures having different mesh shapes are overlapped, (a) a mesh structure of a support structure forming one layer, and (b) a support forming the other layer. The mesh shape of the structure, (c) (a) and (b) are shown superimposed. It is a figure which shows the example which diversified the mesh shape in the support structure which comprises one layer according to the area | region, (a), (b) has shown the mesh shape of each layer. It is a figure explaining the effect | action of the endoprosthesis by this invention suitable for applying to the site | part which has a side branch. It is a figure which shows the other example of the endoprosthesis suitable for applying to the site | part which has a side branch by this invention, (a) Support structure which makes one layer, (b) Support structure which makes another layer (C) The state which looked at the endoprosthesis which comprised the support structure of (a) and the support structure of (b) on each other, and (d) the cross section of the major axis direction is shown. It is a figure which shows the condition at the time of applying the endoprosthesis shown by FIG. 9 to a site | part with a side branch.

Claims (6)

  A number of struts are arranged in the form of a mesh in the circumferential direction of the cylindrical body, and a plurality of struts are arranged in the circumferential direction of the cylindrical body with respect to a single-layer supporting structure formed of a deformable material. Inserting a support structure forming another layer made of a deformable material so as to have a diameter of a size to be inserted into the support structure forming the one layer by combining them so as to form a mesh shape of The support structure forming the one layer and the support structure forming the other layer are joined and fixed in a partial region in the long axis direction, and the support structure forming the one layer is In a region other than a part of the region where the support structure forming another layer is joined, the support columns forming the one layer and the support structure forming the other layer are freely deformed to each other. Possible, the support of the strut in the one-layer support structure The shape of the support and the mesh structure of the support in the other layer are different from each other, so that the entire structure is viewed from the outside and the support mesh in the support structure forming the adjacent layer does not overlap. An endoprosthesis characterized by the presence of a part.   The support structure forming the other layer is inserted into the support structure forming the one layer, and the support structure forming another layer of a cylindrical shape having a smaller diameter is sequentially inserted into the support structure forming the other layer. A support structure that forms a plurality of layers by being inserted inside, and a support structure that forms adjacent layers is joined and fixed in a partial region in the major axis direction to form an entire layer. The struts in the support structure forming the adjacent layer in a region other than a part of the region where the support structure forming the adjacent layer is bonded can be freely deformed to each other. An endoprosthesis according to claim 1 characterized in.   The structure of the support struts of the plurality of layers is a combination of alternating cells that are elements of the struts that expand and maintain the tubular organ, and links or connectors that provide flexibility. The endoprosthesis according to claim 1, wherein the endoprosthesis is one.   In each layer of the support structure forming the plurality of layers, bonding between adjacent layers is performed in at least both end side regions in the axial direction of the entire cylindrical endoprosthesis, and an intermediate region between the regions where the layers are bonded is formed. The mesh structure of the struts in at least a partial region of the part is mainly composed of strut elements that are easily deformed in the circumferential direction of the support structure, and deformation of the tubular organ by deformation of the struts in at least a partial region of the intermediate part. 4. When an endoprosthesis is applied to a site having a side branch, another endoprosthesis can be inserted into the side branch from the endoprosthesis. An endoprosthesis as described in.   The mesh shape of the pillars in at least a part of the middle part of the region where the layers are bonded in the support structure forming at least one layer of the support structures forming the plurality of layers is the circumference of the support structure. The support structure, which is mainly composed of elements of struts which are easily deformed in the direction, and which forms a layer other than the at least one layer forming the plurality of layers, has a length corresponding to a part of the support structure forming the at least one layer. The layers are stacked and bonded so as to form a structure in which a plurality of cylindrical support structures are stacked and bonded over the entire length of the endoprosthesis. 5. An endoprosthesis according to 4. The element of the support column that is easily deformed in the circumferential direction of the support structure is a structure in which a link or a connector as an element of the support column that gives flexibility is elongated in the long axis direction. An endoprosthesis according to any one of the preceding claims.

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