JP6380909B2 - Stent - Google Patents

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. The stent has a cylindrical shape as a whole, and has a small diameter when inserted into a lumen, but is expanded and placed in the lumen. As a method for expanding the diameter of the stent in the lumen, there are self-expansion using a shape memory material and the like, mechanical expansion, and the like in addition to expansion using a balloon.

  By the way, the stent is capable of expanding and contracting as described above, and considering the reduction of the burden on the living body and the improvement of the biofusion, a porous structure or a linear structure in which many through holes are provided in the peripheral wall portion. The strut structure is connected to Specifically, as described in, for example, Japanese Patent Application Laid-Open No. 2007-267844 (Patent Document 1) and the like, a metal tube such as stainless steel or platinum is cut into an appropriate length, and the peripheral wall is cut. It is configured by forming through holes and struts by laser processing.

  However, in such a stent having a conventional structure, since the metal tube as a raw tube has a simple straight cylindrical shape, it has been difficult to form a shape corresponding to an indwelling site in a lumen such as a blood vessel. . Therefore, there is a problem that it is difficult to prepare a stent that accurately matches the shape of the lumen in a lumen, for example, in a portion where the inner diameter dimension changes in a tapered shape or a branch portion such as a bifurcation.

  Moreover, when forming the through holes and struts by subjecting the element tube to laser processing, there is a problem that the yield is poor when the area to be excised is large. In order to improve the yield, a stent obtained by laser processing of a small-diameter cylindrical tube is reduced in diameter and inserted into the lumen, and then expanded to a diameter larger than the initial tube diameter. Although it is conceivable to indwell, there is a possibility that strain and residual stress increase in a diameter-expanded state and it becomes difficult to obtain a stable shape and durability.

  In addition, since the burr-like roughness tends to occur in the laser-processed part and chemical or mechanical post-processing is required, the manufacturing becomes complicated and the accuracy control of the post-processing is also performed. There was a problem that it was difficult.

JP 2007-267844 A

  The present invention has been made in the background of the above-described circumstances, and the problem to be solved is a novel structure in which a shape corresponding to a lumen such as a blood vessel can be realized with a good yield. It is to provide a stent.

That is, the first aspect of the present invention is a stent that can be expanded and contracted in a radial direction and is placed in a body lumen, and is a deformed cylinder in which a branch portion is provided and the number of cylindrical portions is changed in the length direction. It has a shape, has a metal skeleton formed by electroforming , and is characterized in that the branch portion is integrally formed .

In the stent having the structure according to the present embodiment, unlike the one obtained by laser processing of the raw tube of the conventional structure, the shape corresponding to the shape of the lumen is given from the beginning by the skeleton formed by electroforming . Therefore, the portion to be excised can be reduced as compared with the conventional laser-processed stent, and the stent can be manufactured with a good yield.

  Therefore, even when placed in an irregularly shaped lumen such as a blood vessel, the shape corresponding to the lumen is realized with high accuracy, reducing the labor burden of the procedure for the practitioner and the burden on the living body for the patient. Etc. are reduced. 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.

In addition, in the stent having the structure according to the present embodiment, a stent that can be easily applied to a branching portion such as a bifurcation in a lumen such as a blood vessel can be realized.

According to a second aspect of the present invention, in the stent according to the first aspect, a deformed cylindrical shape whose diameter 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, by combining the stent of this aspect with the 1st aspect, in the stent which has a branch part, at least 1 cylinder part can also be made into a taper cylinder shape.

According to a third aspect of the present invention, in the stent according to the first or second aspect, rigidity in at least one end portion in the axial direction is larger than that in the central portion.

  In the case of a stent having a structure according to this aspect, for example, when it is formed by electroforming, the rigidity can be adjusted by increasing the thickness dimension of a specific portion in the length direction or changing the material. It becomes possible. 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.

According to a fourth aspect of the present invention, there is provided the stent according to the third aspect, wherein the end portion whose rigidity is increased as compared with the central portion is reduced in rigidity at the end portion on the axially outer side. 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, adjustment of the rigidity in the terminal portion can be realized by forming only the terminal 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 fifth aspect of the present invention, in the stent according to any one of the first to fourth aspects, the skeleton has a laminated structure of a plurality of types of metals.

  In the case of a stent having a structure according to this aspect, for example, when it is formed by electroforming, it can be formed by a laminated structure of a plurality of types of metals. 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 laminated structure, and the entire skeleton does not have to have a laminated structure.

According to a sixth aspect of the present invention, in the stent according to any one of the first to fifth aspects, the skeleton has a cross-sectional shape whose width dimension changes from the inner peripheral surface toward the outer peripheral surface. is there.

  In the stent having the structure according to this aspect, for example, the degree of freedom in designing the shape of the outer peripheral surface of the stent peripheral wall pressed against the living body, the inner peripheral surface of the stent peripheral wall exposed to blood flow, and the like is improved.

According to a seventh aspect of the present invention, in the stent according to any one of the first to sixth aspects, a weakened portion partially reduced in strength is formed on the skeleton by at least one of electroforming and etching. It is what.

  In the stent having the structure according to this aspect, the fragile portion is formed by electroforming or etching simultaneously with the skeleton, so that the fragile portion can be provided with high dimensional accuracy without the need for post-processing. That is, such a fragile portion is suitable for, for example, obtaining a stent shape along the blood vessel shape by being divided after indwelling, or cutting or deforming in the indwelling procedure to form a branch opening by a technique. Can be adopted.

According to an eighth aspect of the present invention, in the stent according to the seventh 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, when the fragile portion is formed by electroforming, 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 ninth aspect of the present invention, in the stent according to any one of the first to eighth aspects, the skeleton is provided with a recess on the surface.

  In the case of a stent having a structure according to this aspect, for example, when formed by electroforming, a recess is provided at the same time as molding on the surface of the skeleton, or a convex is provided at the same time as molding, so that a relatively concave Can be provided. The surface uneven structure can improve the positioning performance with respect to the surface of the lumen, for example, or can retain the medicine in the recess and place it in the lumen. In addition, the recessed part in this aspect can be formed in any surface of the internal peripheral surface and outer peripheral surface of the surrounding wall made into the cylinder shape. Moreover, the recess in this aspect may be not only a bottomed shape but also a through hole formed by electroforming or etching.

  In addition, it is desirable that the size of the recess in this aspect is an opening size of about 10 to 30 μm, thereby further reducing the patient's foreign body feeling and adversely affecting the strength of the stent as much as possible. To be avoided.

According to the present invention, since the irregular shape is given by the skeleton formed by electroforming , for example, a stent can be obtained in a shape corresponding to the branch portion of the blood vessel from the beginning. In addition, since the stent shape accurately corresponds to the lumen of a blood vessel or the like, the treatment is facilitated, compatibility with a living body is improved, and strain and residual stress of the placed stent itself can be reduced. . In addition, since a portion to be excised is reduced as compared with a conventional laser-processed stent, the stent can be formed with a good yield.

The front view which shows the whole shape of the stent as the 1st Embodiment of this invention. The front view which shows the whole shape of the stent as the 2nd Embodiment of this invention. The front view which shows the whole shape of the stent as the 3rd Embodiment of this invention. Sectional drawing which shows the specific example of the frame | skeleton employable in the stent of this invention. Explanatory drawing which shows schematically the position of the weak part employable in the stent of this invention. Explanatory drawing which shows schematically the position of the suitable weak part in the stent of this invention. The front enlarged view which shows the structural example of the recess employable in the stent of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, FIG. 1 shows a stent 10 as a first embodiment of the present invention in a molded state before being contracted or expanded.

  The stent 10 of the present embodiment includes a trunk cylinder portion 12 and a branch cylinder portion 14 each extending substantially linearly in a substantially cylindrical shape, and is branched by inclining laterally from an intermediate portion in the length direction of the trunk cylinder portion 12. The tube portion 14 extends to form a substantially Y-shaped branch shape as a whole. In other words, in the stent 10 of the present embodiment, the number of tube portions is different in the length direction (vertical direction in FIG. 1) by the branch portion, that is, the stent 10 has a cross-sectional shape in the length direction. The shape of the tube is a deformed irregular shape.

  Each of the trunk tube portion 12 and the branch tube portion 14 is provided with a plurality of annular portions 16 that are continuously curved and bent in a wavy shape and continuously extend in the circumferential direction at a predetermined distance in the axial direction. Thereby, a series of struts 19a constituting the trunk cylinder part 12 and a series of struts 19b constituting the branch cylinder part 14 are respectively formed. And the annular parts 16 and 16 adjacent to each other in the axial direction in the struts 19a and 19b are respectively connected by the link parts 18 extending in the substantially axial direction, thereby forming a cylindrical shape having a predetermined length.

  Particularly in the present embodiment, the annular portion 16 constituting the trunk portion 12 and the annular portion 16 constituting the branch cylinder portion 14 are continuously provided on the circumference of the trunk cylinder portion 12 and the branch cylinder portion 14 in the branch portion. It extends. Thereby, in the branch part of the basic cylinder part 12 and the branch cylinder part 14, the integral structure of each strut 19a, 19b is implement | achieved, and the continuous strut 19 is comprised. In the strut 19, the annular portions 16 and 16 adjacent in the axial direction are connected by the link portion 18, so that the skeleton of the stent 10 of the present embodiment is configured. 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 strut 19 during deformation is prevented.

  The specific shapes of the annular portion 16 and the link portion 18 are not limited in the present invention, and the wave shape of the annular portion 16 and the connection by the link portion 18 are considered in consideration of the characteristics required for the stent 10. A part, the number of the link parts 18 on the periphery of the annular part 16, etc. can be set suitably.

  Moreover, although the width dimension and thickness dimension of the annular part 16 and the link part 18 are not particularly limited, the strut 19 constituting the annular part 16 is about 30 to 150 μm for the purpose of ensuring the strength. The width dimension and the thickness dimension are desirable, and the link portion 18 is desirably a width dimension and a thickness dimension of about 10 to 100 μm.

  Such a branched stent 10 is manufactured by integrally forming a plurality of annular portions 16 and link portions 18 constituting the struts 19 by electroforming.

  Specifically, a molding base having the shapes and sizes of the target trunk cylinder portion 12 and branch cylinder portion 14 is prepared by using a conductor such as stainless steel. Then, an exposed surface is formed in a shape corresponding to each of the plurality of annular portions 16 and the link portions 18 on the surface of the molding base, 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 10 is removed, and the molded base is removed or dissolved, whereby the stent 10 having the above-described target structure can be obtained.

  The stent 10 of the present embodiment having the above-described structure is capable of expanding and contracting in the radial direction in the trunk cylinder portion 12 and the branch cylinder portion 14, and is in a predetermined state from the state before contraction shown in FIG. 1. The diameter is mechanically reduced to the size. In use, the stent 10 is delivered to, for example, a stenosis portion of a blood vessel by a delivery catheter or the like. Thereafter, the stent 10 is expanded by a balloon catheter, or when the stent 10 is formed of a shape memory material, the stent 10 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 10 of this embodiment is produced by electroforming, the branched shape which has the basic cylinder part 12 and the branch cylinder part 14 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 10 that accurately corresponds to a complicated shape portion such as a blood vessel of a living body with a good yield.

  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 10, so that a straight cylindrical metal fitting having a conventional structure is laser processed. Compared to the obtained stent, it is possible to obtain a stent with various irregular initial shapes.

  For example, as shown in FIG. 2, the stent 20 as the second embodiment of the present invention having a tapered cylindrical shape whose inner and outer diameter dimensions change in the axial direction also has an initial shape with a target taper angle. It can be integrally formed by casting. The stent 20 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 of the first embodiment are denoted by the same reference numerals as those of the first embodiment in the drawings, and detailed description thereof is omitted.

  Since such a stent 20 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 10 and 20 as described above, that is, the struts 19 and the link portions 18 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.

  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 16 and the link portion 18 can be formed of different metal materials, and the material of the annular portion 16 can be partially different in the length direction and the circumferential direction of the stent 10. become.

  Specifically, as shown in FIG. 3, as a third embodiment of the present invention, in a straight cylindrical stent 30, one or a plurality of annular portions positioned at the axial ends thereof Only 16 can be made thicker by increasing the number of times of electroforming than the other annular portion 16 located in the central portion in the axial direction. That is, in the stent 30 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.

  As described above, in the deformed cylindrical stent 30 in which the axial end is thicker than the central portion, the rigidity of the axial end is made larger than that of the central portion, so that deformation in the central portion is achieved. 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 the annular portions 16 and 16 located at the end portions in the axial direction and adjacent to each other. It is also possible to form the annular portion 16 shifted 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 addition, in the stent 30 of this embodiment, it is preferable that the rigidity of the axially outer end portion is substantially the same as or smaller than that of the central portion at the axial end portion 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 10, 20, and 30 as described above are manufactured by electroforming, the design freedom of the cross-sectional shape of the strut 19 constituting the skeleton is also a simple rectangular cross-section in the conventional laser processing. On the other hand, a large degree of freedom can be secured. For example, FIGS. 4A and 4B show a cross-sectional shape of the strut 19 in which the width dimension changes from the inner peripheral surface toward the outer peripheral surface. 4 (a) and 4 (b), the upper side is the side in contact with the blood vessel wall, and the lower side is the side located in the blood vessel lumen.

  Specifically, as shown in FIG. 4A, a strut 19 having a triangular cross section can also be used. In the strut 19 having such a shape, the side in contact with the blood vessel wall is gradually narrowed, so that the pressing force against the blood vessel wall of the stent can be concentrated on the tapered portion of the strut 19 when the stent is expanded. 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 19 bites in and breaks against the calcified lesion portion. Vascularized vessels can also be dilated.

  Further, as shown in FIG. 4B, a strut 19 having a cross section of an inverted triangle shape can be used. In the strut 19 having such a shape, since the side located in the blood vessel lumen is gradually narrowed, the area in contact with the blood flow is reduced, and the foreign body reaction 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. Further, 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 19 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 19 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. However, the cross-sectional shape of the strut 19 is not limited to the triangular shape or the inverted triangular shape shown in FIGS. 4A and 4B, and for example, a semicircular shape or a double tapered shape may be employed. .

  Furthermore, since the stents 10, 20, and 30 as described above are manufactured by electroforming, the cross-sectional shape of the link portion 18 that connects the annular portions 16 and 16 and the degree of freedom in designing the strength and brittleness are also large. 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 stent 10, 20, and 30, a weakened portion whose strength is smaller than that of the annular portion 16 is configured by the link portion 18 in the skeleton. By producing such a link portion 18 by electroforming, only a thin shape can be formed in the width direction of the strut 19 by the laser processing of the conventional structure, but not only the thin shape but also the thickness of the strut 19 is formed. Thin shapes can also be formed in the vertical direction. Further, the cross-sectional shape of the link portion 18 is only a simple rectangular cross-section in the conventional laser processing, but a shape other than the rectangular shape can be formed.

  Specifically, for example, as shown in FIGS. 5A to 5C, the position of the link portion 18 in the thickness direction can be appropriately changed in design with respect to the annular portions 16 and 16. In FIG. 5, the upper side indicates the blood vessel wall side, and the lower side indicates the blood vessel lumen side. That is, in FIG. 5 (a), the annular portions 16, 16 are connected by the link portion 18 on the blood vessel wall side, while in FIG. 5 (b), the annular portions 16, 16 are the link portion at the central portion in the thickness direction. 18 are connected. In FIG. 5C, the annular portions 16 are connected by a link portion 18 on the blood vessel lumen side. Furthermore, it is possible to combine the link portions 18 located on the blood vessel wall side, the central portion, and the blood vessel lumen side. In FIG. 5, the strut 19 and the link portion 18 are shown as a rectangular cross section, but FIG. 5 merely shows the relative positions of the annular portions 16 and 16 and the link portion 18, and the strut 19 and the link portion 18. The shape of is not limited in any way.

  As described above, in the conventional laser processing, since one pipe is formed penetrating in the thickness direction, the annular portion and the link portion can only be formed with the same thickness. , 20, and 30 can be manufactured by electroforming to reduce the thickness of the link portion 18. Thereby, the link part 18 can be formed thinly and thinly, and when the link part 18 is cut | disconnected, it is made easy to cut | disconnect more easily than before. Conventionally, a method in which the annular portion 16 and the link portion 18 are formed separately and then fixed together has been adopted. However, by manufacturing the stents 10, 20, and 30 by electroforming, The link portion 18 is integrally formed, and manufacturing can be facilitated while ensuring high dimensional accuracy. Furthermore, since the cut surface of the link part 18 is made small, irritation | stimulation by a cut surface contacting a blood vessel wall etc. can be suppressed as much as possible.

  Further, the position of the link portion 18 can be appropriately changed in design with respect to the width direction of the strut 19 and can be formed at the end portion in the width direction with respect to the strut 19, but is shown in FIG. As described above, the link portion 18 is preferably formed at the central portion in the width direction of the strut 19. In particular, as shown in FIG. 6, the link portion 18 is preferably located at the central portion of the strut 19 even in the thickness direction. Thereby, the possibility that the cut surface of the link portion 18 contacts the blood vessel wall is further reduced, and the discomfort given to the patient can be further reduced.

  6, the strut 19 and the link portion 18 are shown as a rectangular cross section, but FIG. 6 merely shows the relative positions of the annular portion 16 and the link portion 18. The shape is not limited at all.

  Furthermore, since the stents 10, 20, and 30 as described above are manufactured by electroforming, by appropriately setting the shape of the molding base and mask used for electroforming, the surface can be appropriately embossed or the like. It is also possible to transfer the shape.

  Specifically, for example, the surface of the molding base is subjected to a treatment such as etching to give an appropriate shape such as embossing, thereby embossing the outer peripheral surface of the stent formed by electrodeposition on the surface of the molding base. It can be easily formed by transferring the shape.

  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.

  Furthermore, since the stents 10, 20, and 30 as described above are manufactured by electroforming, by appropriately setting the shape of the molding base and the mask used for electroforming, the surface has an arbitrary size. It is also possible to form a recess.

Specifically, for example, by treating the surface of the molding base with a protrusion or the like, a concave having a size corresponding to the inner peripheral surface of the stent 10, 20, 30 formed by electrodeposition on the surface. It can be formed by transferring the area. Further, by carrying out the pre electroforming central portion of the forming surface of the link portion 18 in the form of island-like mask electroforming, a peripheral wall surrounding a portion of the island-shaped mask is formed by electroforming It is also possible to form a recess opening in the outer peripheral surface of the stent 10, 20, 30 in the central mask portion. Such a recess can be formed in an arbitrary shape and size. For example, in addition to a hole such as a circular shape, the length direction of the strut 19 and the link portion 18 as shown in FIG. It is also possible to form the recess 32 with a groove shape or the like extending in the direction, and a large degree of design freedom can be ensured.

  Further, since the stents 10, 20, and 30 as described above are produced by electroforming, for example, eutectoid is performed using eutectoid plating technology using an electrolytic solution in which non-conductive powder is dispersed. It is also possible to give a porous structure or a microporous structure corresponding to the fine particles to the strut 19 or the connecting portion 18.

  Thus, by forming the strut 19 and the link portion 18 with the recess 32 and the porous structure, the amount of metal constituting the stent can be reduced. In addition, by loading a drug in the recess 32 or the porous structure, for example, a drug-eluting stent as described above can be configured, and the drug can be effectively eluted into the blood vessel wall.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited by the specific descriptions, and is implemented in a mode in which various changes, modifications, improvements, and the like are added based on the knowledge of those skilled in the art. Any of such embodiments can be included in the scope of the present invention without departing from the spirit of the present invention.

  For example, all of the stents 10, 20, and 30 described in the above embodiments have an initial shape, and are given an expanded shape when placed in a lumen. That is, when inserted into a lumen such as a blood vessel, the diameter is reduced and delivered by a catheter. When these stents 10, 20, and 30 are of a balloon expandable type, they are expanded using a balloon. In this way, it is placed in a state of being pressed against the inner peripheral surface of the blood vessel. Further, if the metal material is a self-expanding type, it is automatically expanded by being released from the delivery catheter. In such an expanded state, the substantially initial shape is obtained, so that the expanded state shape is stably expressed, and distortion and residual stress in the expanded indwelling state are effectively suppressed. However, the present invention 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 indwelling.

  Further, in addition to the simple Y-shaped branch shape, taper shape, and thick end shape as illustrated, stents having different diameter dimensions of the basic cylinder portion and the branch cylinder portion, and at least one of the basic cylinder portion and the branch cylinder portion The present invention includes various types of stents, such as a stent having a tapered cylindrical shape, a stent partially tapered in the length direction, and a stent having a thick portion at the end or center in the length direction. Applicable to shaped stents.

  Furthermore, 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 way, when the link portion is not provided, the skeleton of the stent is configured only by the struts.

  Furthermore, the strut thickness 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.

  Further, the recess 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 a cavity after the drug or the like is eluted, blood can pass through the through-hole, and the blood flow is not hindered compared to a case where, for example, the recess is bottomed. . However, the recess formed in the stent does not need to be formed by electroforming. For example, after forming the stent by electroforming, a through-hole as a recess may be formed by laser processing or the like.

  In addition, the drug may be directly placed in the recess, for example, a biodegradable resin cotton impregnated with the drug or a capsule encapsulating the drug may be placed in the recess.

  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.

  In the present invention, a stent may be manufactured using an etching technique instead of the above-described electroforming. Examples of the etching technique include the following techniques. A metallic molding base having the desired stent shape and size is prepared. And on the surface of this shaping | molding base, a corrosion-resistant mask is given in the shape corresponding to each some annular part and link part, and the non-masked part exposes a shaping | molding base. Thereafter, it is immersed in a polishing liquid composed of strong acid, strong alkali, strong oxidizing agent, etc., and the unmasked portion of the molding base is corroded and dissolved to obtain a stent having the target structure as described above. Can do.

  Since the etching technology produces the stent by corrosive dissolution of the unmasked part of the molded base, the thickness of the molded base is almost the same as the thickness of the finished product, and the thickness of the finished product takes time. Can be set larger. In addition, since the etching technique does not require a liquid sample dedicated to electroforming, the material selectivity is increased. Furthermore, since the etching technique does not require a current to flow, it is not necessary to electrically adjust the current density, voltage, etc., and manufacturing conditions can be easily set and managed. In the present invention, a skeleton can be formed by combining electroforming and etching. For example, a partial etching process can be performed on the skeleton formed by electroforming.

10, 20, 30: stent, 16: annular portion, 18: link portion (fragile portion), 19: strut, 32: recess

Claims (8)

A stent that is radially expandable and contracted and is placed in a body lumen,
It has a deformed cylindrical shape in which the number of tube portions is changed in the length direction provided with a branch portion , and has a metal skeleton formed by electroforming , and the branch portion is integrally formed A stent characterized by The stent according to claim 1, wherein the stent has a deformed cylindrical shape whose diameter is changed in the length direction. The stent according to claim 1 or 2 , wherein rigidity at at least one end portion in the axial direction is larger than that of the central portion. The stent according to claim 3 , wherein the end portion whose rigidity is increased as compared with the central portion is reduced in rigidity at an end portion on the outer side in the axial direction. The stent according to any one of claims 1 to 4 , wherein the skeleton has a laminated structure of a plurality of types of metals. The stent according to any one of claims 1 to 5 , wherein a weakened portion having a partially reduced strength is formed in the skeleton by at least one of electroforming and etching. The stent according to claim 6 , wherein the fragile portion is easily deformed with a smaller cross-sectional area than other portions of the skeleton. The stent according to any one of claims 1 to 7 , wherein a recess is provided on a surface of the skeleton.