Covered stent and manufacturing method for covered stent

Abstract

To provide a covered stent including an inner film part and an outer film part for covering a frame part, offering excellent durability by improving adhesiveness between the inner film part and the outer film part, and to provide a manufacturing method for the same.SOLUTION: A covered stent 100 includes: a cylindrical frame part 102 capable of being expanded and deformed to a radial outer side; an inner film part 104 for covering at least a part of the inner peripheral surface of the frame part 102; and an outer film part 106 for covering at least a part of the outer peripheral surface of the frame part 102 and making contact with the inner film part 104. One of the inner film part 104 and the outer film part 106 is constituted by a fine structure film having a large number of recesses 105 formed in the outer peripheral surface, and the other of the inner film part 104 and the outer film part 106 is constituted by a resin film comprising a resin material. The resin material constituting the resin film intrudes into the recesses 105 of the fine structure film in a boundary surface on which the resin film and the fine structure film make contact with each other.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a covered stent to be placed in the body and a method for manufacturing the covered stent. [Background technology]

[0002] Conventionally, stent placement is known in which a stent is placed in the body to ensure the patency of digestive or circulatory organs or to bypass organs. Stents used in stent placement are classified into self-expanding and balloon-expanding types according to the type of expansion. In addition, there are covered stents in which the circumferential surface of the stent is covered with a coating film made of a resin material or the like.

[0003] Regarding conventional covered stents, the techniques described in, for example, Patent Documents 1 and 2 below are known.

[0004] Patent Document 1 describes that a coating layer is formed on the outer surface of a hollow mesh cylinder that constitutes a stent, and that the coating layer can be formed by immersing the hollow mesh cylinder in a PTFE (polytetrafluoroethylene) material. Patent Document 2 describes a medical device (stent) that is made of a plurality of different materials and has a sleeve that forms a plurality of regions with different properties such as porosity, pore size, thickness, etc., and the pores of the sleeve are filled with a degradable material such as a bioabsorbable material and bonded. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2004-344634 A [Patent Document 2] Patent No. 5934163 Summary of the Invention [Problem to be solved by the invention]

[0006] A covered stent has a structure in which a coating film is coated on the peripheral surface of a frame part that constitutes the framework of the stent, and the coating film needs to be attached so as not to peel off (dissociate) from the frame part. However, depending on the material used for the coating film, it is not easy to attach it firmly to the frame part, and there is a problem that the coating film peels off from the frame part. In addition, when an inner membrane part and an outer membrane part that cover the inner peripheral side and the outer peripheral side, respectively, are provided, there is a problem that the adhesive strength between the inner membrane part and the outer membrane part cannot be sufficiently ensured, and the inner membrane part or the outer membrane part peels off from the frame part.

[0007] Patent Document 1 describes forming a coating layer by immersing a hollow mesh cylinder in PTFE material, and Patent Document 2 describes filling the pores of the sleeve that form the different regions with a degradable material such as a bioabsorbable material and adhering them, but there is no description or suggestion whatsoever about the adhesion between the frame portion and the covering membrane, or the adhesion between the inner membrane portion and the outer membrane portion when an inner membrane portion and an outer membrane portion are provided to cover the inner and outer sides of the frame portion, respectively.

[0008] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a covered stent comprising a frame portion and an inner membrane portion and an outer membrane portion covering the inner and outer circumferential sides, respectively, of the frame portion, which has excellent durability by improving the adhesion between the inner membrane portion and the outer membrane portion, and to provide a method for manufacturing such a covered stent. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the covered stent of the present invention is a covered stent comprising a tubular frame portion capable of expanding and deforming radially outward, an inner membrane portion covering at least a portion of the inner surface of the frame portion, and an outer membrane portion covering at least a portion of the outer surface of the frame portion and in contact with the inner membrane portion, wherein one of the inner membrane portion and the outer membrane portion is composed of a microstructure film having a number of recesses formed on its peripheral surface, and the other of the inner membrane portion and the outer membrane portion is composed of a resin film made of a resin material, and at the interface where the resin film and the microstructure film contact each other, the resin material constituting the resin film has penetrated into the recesses of the microstructure film.

[0010] According to the above configuration, a large number of recesses are formed on the peripheral surface of the microstructure film that comes into contact with the resin film, and the resin material that constitutes the resin film penetrates into the recesses of the microstructure film, thereby improving the adhesive strength between the microstructure film and the resin film and integrating them together. This makes it possible to provide a covered stent with excellent durability by suppressing peeling of the microstructure film and the resin film that cover the frame portion so as to sandwich the frame portion on the inner and outer peripheral surfaces.

[0011] In the covered stent according to the present invention, in the above configuration, the microstructure film may be made of a porous material or nonwoven fabric containing a large number of micropores.

[0012] According to the above configuration, by selecting a porous material or nonwoven fabric containing a large number of micropores as the material for the microstructure film, it is possible to easily and reliably select a microstructure film having recesses formed on its peripheral surface by a large number of micropores.

[0013] In the covered stent according to the present invention, in the above configuration, the resin material may be a silicone compound, a thermoplastic polymer, or an elastomer.

[0014] According to the above-mentioned configuration, it is possible to easily and reliably select a resin material that has the property of solidifying from a molten state, a plastic state, or a solution state.

[0015] In the covered stent according to the present invention, in the above-mentioned configuration, the resin material may have the property of solidifying from a molten state, a plastic state, or a solution state after being placed on the inner or outer circumferential surface of the frame portion.

[0016] According to the above configuration, a resin material in a molten, plastic or solution state can be placed on the inner or outer surface of the frame portion, and the resin material can be solidified while penetrating into the recesses of the microstructure film to form a resin film.

[0017] In the covered stent according to the present invention, in the above configuration, the resin material may contain a resin reaction liquid that reacts with a polymerization initiator or a curing agent and solidifies.

[0018] According to the above configuration, a resin material containing a resin reaction liquid as a main liquid is applied onto the inner or outer surface of the frame portion, and a polymerization initiator or a curing agent is used to cause a polymerization reaction or a cross-linking reaction, thereby solidifying the resin material and forming a resin film.

[0019] In the covered stent according to the present invention, in the above-mentioned configuration, the resin film may be formed by polymerizing and solidifying a prepolymer, which is the resin material.

[0020] According to the above configuration, a prepolymer, which is a resin material, is placed on the inner or outer peripheral surface of the frame portion, and then a polymerization reaction is caused by a polymerization initiator, thereby solidifying the resin material to form a resin film.

[0021] In the covered stent according to the present invention, in the above configuration, the prepolymer may contain a monomer.

[0022] According to the above configuration, by forming the prepolymer from a monomer before the polymerization reaction, the prepolymer resin material can be placed on the inner or outer peripheral surface of the frame portion, and then a polymerization reaction can be carried out to solidify the resin material, thereby forming a resin film.

[0023] In the covered stent according to the present invention, in the above configuration, the resin material may be in a state of permeating into the recesses formed in the microstructure film.

[0024] According to the above-mentioned configuration, the resin material in a molten state, a plastic state, or a solution state is permeated into the recesses formed in the microstructure film and solidified, so that the resin film and the microstructure film are bonded in a state where the resin material has permeated into the microstructure film, and the adhesive strength between the microstructure film and the resin film can be improved. In particular, the resin material in a molten state or a solution state is in a liquid state, so that it is easy to permeate into the microstructure film, and it is expected to improve the adhesive strength between the microstructure film and the resin film.

[0025] In the covered stent according to the present invention, in the above configuration, the inner membrane portion may be formed of the microstructure film, and the outer membrane portion may be formed of the resin film.

[0026] According to the above-mentioned configuration, it is possible to provide a covered stent in which a microstructure film, a frame portion, and a resin film are laminated in this order from the inner periphery side.

[0027] In the covered stent according to the present invention, in the above configuration, the inner membrane portion may be formed of the resin film, and the outer membrane portion may be formed of the microstructure film.

[0028] According to the above-mentioned configuration, it is possible to provide a covered stent in which a resin film, a frame portion, and a microstructure film are laminated in this order from the inner periphery side.

[0029] The covered stent according to the present invention, in the above-mentioned configuration, may be a digestive stent that is placed in an organ of the digestive system.

[0030] According to the above configuration, it is possible to provide a covered stent having excellent durability that can be used as a digestive stent to be placed in an organ of the digestive system.

[0031] The covered stent according to the present invention, in the above-mentioned configuration, may be a circulatory stent that is placed in a circulatory system organ.

[0032] According to the above configuration, it is possible to provide a covered stent having excellent durability that can be used as a circulatory stent to be placed in an organ of the circulatory system.

[0033] In order to achieve the above-mentioned object, the manufacturing method of the covered stent according to the present invention is characterized in that it comprises the steps of: preparing a tubular frame portion constituting the covered stent, which can be expanded and deformed radially outward; preparing a mold member having a cylindrical surface along the frame portion; arranging, on the cylindrical surface of the mold member, a microstructure film covering at least a part of one of the inner and outer circumferential sides of the frame portion and having a number of recesses formed on its circumferential surface; a resin material covering at least a part of the other of the inner and outer circumferential sides of the frame portion; and the frame portion; and solidifying the resin material from a molten, plastic, or solution state to form a resin film that covers at least a part of the other surface and contacts the microstructure film with the resin material penetrating the recesses of the microstructure film.

[0034] According to the above process, a large number of recesses are formed on the peripheral surface of the microstructure film that comes into contact with the resin film, and the resin material that constitutes the resin film penetrates into the recesses of the microstructure film, thereby improving the adhesive strength between the microstructure film and the resin film and integrating them together. This makes it possible to provide a covered stent with excellent durability by suppressing peeling of the microstructure film and the resin film that cover the frame portion by sandwiching them on the inner and outer peripheral surfaces of the frame portion.

[0035] In the above-mentioned steps of the method for producing a covered stent according to the present invention, the microstructure film may be made of a porous material or a nonwoven fabric containing a large number of micropores.

[0036] According to the above process, by selecting a porous material or nonwoven fabric containing a large number of micropores as the material for the microstructure membrane, it is possible to easily and reliably select a microstructure membrane having recesses formed on its peripheral surface by a large number of micropores.

[0037] In the method for producing a covered stent according to the present invention, in the above-mentioned step, the resin material may be a silicone compound, a thermoplastic polymer, or an elastomer.

[0038] According to the above process, it is possible to easily and reliably select a resin material that has the property of solidifying from a molten state, a plastic state, or a solution state.

[0039] In the above-mentioned process for producing a covered stent according to the present invention, the resin material in a molten, plastic or solution state may be placed on the inner or outer circumferential surface of the frame portion and solidified.

[0040] According to the above process, a resin material in a molten, plastic or solution state can be placed on the inner or outer peripheral surface of the frame portion, and the resin material can be solidified while penetrating into the recesses of the microstructure film to form a resin film.

[0041] In the manufacturing method for a covered stent according to the present invention, in the above-mentioned process, the resin material may contain a resin reaction liquid that reacts with a polymerization initiator or a curing agent to solidify, and the resin reaction liquid may be solidified by a reaction with the polymerization initiator or the curing agent.

[0042] According to the above process, a resin material containing a resin reaction liquid as a main liquid is applied onto the inner or outer peripheral surface of the frame portion, and a polymerization initiator or a curing agent is used to cause a polymerization reaction or a cross-linking reaction, thereby solidifying the resin material and forming a resin film.

[0043] In the method for producing a covered stent according to the present invention, in the above-mentioned step, a prepolymer may be used as the resin material, and the prepolymer may be polymerized and solidified to form a resin film.

[0044] According to the above process, a prepolymer, which is a resin material, is placed on the inner or outer peripheral surface of the frame portion, and then a polymerization reaction is caused by a polymerization initiator, thereby solidifying the resin material to form a resin film.

[0045] In the method for producing a covered stent according to the present invention, in the above steps, the prepolymer may contain a monomer.

[0046] According to the above process, by forming the prepolymer from a monomer prior to the polymerization reaction, the prepolymer resin material can be placed on the inner or outer peripheral surface of the frame portion and then polymerized, thereby solidifying the resin material to form a resin film.

[0047] In the above-mentioned step of the method for producing a covered stent according to the present invention, the resin material in a molten state, a plastic state or a solution state may be allowed to penetrate into the recesses formed in the microstructure film.

[0048] According to the above process, the resin material in a molten state, plastic state, or solution state is permeated into the recesses formed in the microstructure film and solidified, so that the resin film and the microstructure film are bonded in a state where the resin material has permeated into the microstructure film, and the adhesive strength between the microstructure film and the resin film can be improved. In particular, the resin material in a molten state or solution state is in a liquid state, so that it is easy to permeate into the microstructure film, and it is expected to improve the adhesive strength between the microstructure film and the resin film.

[0049] In the above-mentioned step of the method for producing a covered stent according to the present invention, the resin material in a molten state, a plastic state or a solution state may be permeated into the recesses formed in the microstructure film under negative pressure.

[0050] According to the above process, air bubbles contained in the microstructure film can be removed, and the resin material in a molten, plastic or liquid state can be reliably permeated into the interior of the microstructure film.

[0051] The method for manufacturing a covered stent according to the present invention may, in the above-mentioned steps, produce a covered stent in which the microstructure film is formed on the inner peripheral surface of the frame part and the resin film is formed on the outer peripheral surface of the frame part by arranging the microstructure film, the frame part, and the resin material in that order on the outer peripheral surface of the cylindrical mold member.

[0052] According to the above process, it is possible to provide a covered stent in which the microstructure film, the frame portion, and the resin film are laminated in this order from the inner periphery side.

[0053] The method for manufacturing a covered stent according to the present invention may, in the above-mentioned steps, produce a covered stent in which the microstructure film is formed on the outer peripheral surface of the frame part and the resin film is formed on the inner peripheral surface of the frame part by arranging the microstructure film, the frame part, and the resin material in that order on the inner peripheral surface of the cylindrical mold member.

[0054] According to the above process, it is possible to provide a covered stent in which the resin film, the frame portion, and the microstructure film are laminated in this order from the inner periphery side.

[0055] In the method for producing a covered stent according to the present invention, in the above steps, a digestive stent to be placed in an organ of the digestive system may be produced as the covered stent.

[0056] According to the above steps, it is possible to provide a covered stent having excellent durability that can be used as a digestive stent to be placed in an organ of the digestive system.

[0057] In the method for producing a covered stent according to the present invention, in the above steps, a circulatory stent to be placed in an organ of the circulatory system may be produced as the covered stent.

[0058] According to the above steps, it is possible to provide a covered stent having excellent durability that can be used as a circulatory stent to be placed in a circulatory system organ. [Brief description of the drawings]

[0059] [Figure 1] FIG. 1 is a side view showing an example of a covered stent in the first and second embodiments of the present invention. [Diagram 2] FIG. 1 is a cross-sectional view of a covered stent in a first embodiment of the present invention. [Diagram 3] 3A and 3B are partial enlarged views of a region R2 in FIG. 2, in which (a) is a view showing an example of the region R2 in FIG. 2, and (b) is a view showing another example of the region R2. [Figure 4] 5 is a flowchart showing an example of a method for manufacturing the covered stent in the first embodiment of the present invention. [Diagram 5] FIG. 2 is a side view showing a mold member used in an example of a manufacturing method for the covered stent in the first embodiment of the present invention. [Figure 6] FIG. 5 is a cross-sectional view illustrating an example of a method for producing a covered stent in the first embodiment of the present invention, showing a state near the outer circumferential surface of a cylindrical mold member (region R3 in FIG. 5). [Figure 7] FIG. 4 is a cross-sectional view of a covered stent in a second embodiment of the present invention. [Figure 8] 10 is a flowchart showing an example of a method for manufacturing a covered stent in a second embodiment of the present invention. [Figure 9] FIG. 5 is a cross-sectional view illustrating an example of a method for producing a covered stent in a second embodiment of the present invention, showing a state near the outer circumferential surface of a cylindrical mold member (region R3 in FIG. 5). [Figure 10] 10 is a flowchart showing another example of the method for manufacturing the covered stent in the second embodiment of the present invention. [Figure 11] FIG. 11 is a side view showing a mold member used in another example of the method for producing a covered stent in the second embodiment of the present invention. [Figure 12] FIG. 11 is a cross-sectional view illustrating a state near the inner circumferential surface of a cylindrical mold member (region R5 in FIG. 11) for explaining another example of the method for producing a covered stent in the second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0060] Hereinafter, the covered stent according to the first and second embodiments of the present invention will be described with reference to the drawings. The drawings referred to in this specification are not necessarily drawn to exact scale with respect to the actual dimensions, and some parts are exaggerated or simplified to show the configuration according to the present invention in a schematic manner.

[0061] The use of the covered stent in the first and second embodiments of the present invention is not particularly limited, and it may be used as a digestive stent placed in a digestive organ, or as a circulatory stent placed in a circulatory organ, or as a digestive organ bypass stent for bypassing digestive organs.

[0062] (Configuration of Covered Stent Common to First and Second Embodiments) Fig. 1 is a side view showing an example of a covered stent 100 according to the first and second embodiments of the present invention. Fig. 1 shows a cylindrical self-expanding covered stent 100 that expands from a contracted state by its own elasticity.

[0063] The covered stent 100 is intended to be placed inside the body and is roughly composed of a tubular frame portion 102, an inner membrane portion 104 covering at least a portion of the inner surface of the frame portion 102, and an outer membrane portion 106 covering at least a portion of the outer surface of the frame portion 102 and being in partial contact with the inner membrane portion 104.

[0064] The frame portion 102 is a bare stent formed in a cylindrical shape, and has a lumen extending in the axial direction therein. As shown in FIG. 1 as an example, the frame portion 102 has a structure in which struts 102a, which are wire materials, are combined in a zigzag pattern to form a circular ring, and adjacent struts 102a are partially connected in the axial direction by bridges 102b. This frame structure imparts flexibility in the radial direction, and a configuration in which the cross-sectional area of ​​the lumen of the frame portion 102 can be greatly changed in response to a force applied radially inward, that is, a self-expanding stent that can be expanded and deformed radially outward from a contracted state by its own elastic force, is realized. However, the covered stent 100 in the first and second embodiments of the present invention may be a balloon-expandable stent that is expanded and contracted by a balloon.

[0065] The wire material constituting the frame portion 102 is preferably a superelastic alloy or a shape memory alloy such as a nickel-titanium alloy or a cobalt-chromium alloy, but may be other metals or resins such as stainless steel. The frame portion 102 constitutes the skeleton of the covered stent 100, and the radial and axial lengths of the frame portion 102 are substantially the same as the radial and axial lengths of the covered stent 100. The radial and axial lengths of the frame portion 102 can be appropriately selected depending on the application, and are preferably selected to suit the organ or the like to be placed in the body. The covered stent 100 is capable of being carried to a desired position in the body in a contracted state by a stent delivery system by the frame portion 102 expanding and contracting in the radial direction, and then being placed in the body by expanding the frame portion 102 at the desired position.

[0066] 1 shows a laser-cut type stent as a covered stent 100 in the first and second embodiments of the present invention, in which a circular tubular material is laser-cut to form a mesh-like cylinder composed of wires (struts 102a) having numerous bent portions, but the type of stent is not particularly limited, and may be, for example, a braided type stent formed by weaving or braiding wires (filaments). In the case of a laser-cut type stent, the cross section of the wire is usually rectangular, and in the case of a braided type stent, the cross section of the wire is circular (round wire).

[0067] Although not shown in FIG. 1, the covered stent 100 in the first and second embodiments of the present invention may be configured with a flare portion (head portion) in which a portion of the stent body (e.g., the axial end portion of the frame portion 102) expands radially to prevent migration at the placement position and achieve good patency, and may be equipped with a hooking portion for preventing migration, an X-ray fluoroscopy contrast marker that allows the position of the covered stent 100 to be easily confirmed under X-ray fluoroscopy, or the like.

[0068] The inner membrane portion 104 is attached to the frame portion 102 so as to cover at least a part of the inner circumferential surface of the frame portion 102. On the other hand, the outer membrane portion 106 is attached to the frame portion 102 so as to cover at least a part of the outer circumferential surface of the frame portion 102. That is, the covered stent 100 in the first and second embodiments of the present invention has a configuration in which the inner membrane portion 104, the frame portion 102, and the outer membrane portion 106 are layered in this order toward the radially outer side of the tubular frame portion 102.

[0069] The inner membrane portion 104 and the outer membrane portion 106 may be provided so as to cover the entire peripheral surface of the frame portion 102 in the axial direction, or may be provided so as to cover only a part of the peripheral surface of the frame portion 102 in the axial direction. FIG. 1 shows, as an example, a covered stent 100 in which the inner membrane portion 104 and the outer membrane portion 106 cover only a part of the peripheral surface of the frame portion 102 in the axial direction. The covered stent 100 shown in FIG. 1 has a covered region 108a covered by the inner membrane portion 104 and the outer membrane portion 106, and an uncovered region 108b that is not covered by the inner membrane portion 104 and the outer membrane portion 106. The axial positions of the covered region 108a and the uncovered region 108b can be set as appropriate.

[0070] The inner membrane portion 104 and the outer membrane portion 106 are in contact with each other through the mesh (gaps formed by wires) formed in the frame portion 102 in at least a part of the covered region 108a. The inner membrane portion 104 and the outer membrane portion 106 are in a state of facing each other at least in part, and may have an interface (contact surface) where they are in contact with each other, but in order to improve the adhesion between the inner membrane portion 104 and the outer membrane portion 106, it is preferable that the contact area between the inner membrane portion 104 and the outer membrane portion 106 is large. Note that the inner membrane portion 104 and the outer membrane portion 106 may be in contact with each other at least in part, and may be provided in asymmetric positions across the frame portion 102, for example, in a region where the inner membrane portion 104 is arranged but the opposing outer membrane portion 106 is not arranged, or in a region where the outer membrane portion 106 is arranged but the opposing inner membrane portion 104 is not arranged.

[0071] The inner membrane portion 104 and the outer membrane portion 106 are made of different materials. More specifically, one of the inner membrane portion 104 and the outer membrane portion 106 is made of a microstructure film, and the other of the inner membrane portion 104 and the outer membrane portion 106 is made of a resin film. As will be described later, in the covered stent 100 in the first embodiment, the inner membrane portion 104 is made of a microstructure film, and the outer membrane portion 106 is made of a resin film, and in the covered stent 100 in the second embodiment, the inner membrane portion 104 is made of a resin film, and the outer membrane portion 106 is made of a microstructure film.

[0072] (Covered stent in the first embodiment) The covered stent 100 according to the first embodiment of the present invention will be described below. Fig. 2 is a cross-sectional view of the covered stent 100 according to the first embodiment of the present invention. Fig. 2 shows a cross-sectional view taken along line AA in Fig. 1, and a partially enlarged view showing the state of the vicinity of the interface (region R1) between the microstructure film and the resin film.

[0073] As shown in FIG. 2, in the covered stent 100 of the first embodiment, the inner membrane portion 104 is composed of a microstructure film, and the outer membrane portion 106 is composed of a resin film, and the microstructure film constituting the inner membrane portion 104, the frame portion 102, and the resin film constituting the outer membrane portion 106 are laminated in this order toward the radially outward side of the tubular frame portion 102.

[0074] The microstructure membrane constituting the inner membrane portion 104 can be made of, for example, a material containing a large number of micropores. As an example, the microstructure membrane can be made of a porous material or nonwoven fabric containing a large number of micropores therein.

[0075] A number of recesses 105 are formed on the peripheral surface of the microstructure film facing the resin film. The recesses 105 formed on the peripheral surface of the microstructure film are formed by a number of micropores that are exposed and open on the peripheral surface. The size of the micropores (pore size) is not particularly limited, but the average size is, for example, about 0.1 to 100 μm, and preferably about 0.1 to 10 μm.

[0076] Nonwoven fabrics that can be used as microstructured membranes are those defined in JIS-L0222, and refer to fiber sheets, webs, or pads in which the fibers are oriented in one direction or randomly, and the fibers are bonded together by entanglement, fusion, or adhesion. Porous materials that can be used as microstructured membranes refer to materials other than the above nonwoven fabrics that have fine spaces or holes through which liquids or gases can pass, and are processed into sheets or films.

[0077] As the microstructured membrane, a porous material containing many micropores therein can be selected. Examples of porous materials that can be used as the microstructured membrane include ePTFE (expanded polytetrafluoroethylene), vinyl polymers (e.g., polyethylene, polypropylene, polystyrene, polyacrylate, polymethacrylate, polyacrylamide, polymethacrylamide, polyvinyl chloride, polyvinylidene chloride, polyvinylidene fluoride, polyhexafluoropropene, polyvinyl ether, polyvinylcarbazole, polyvinyl acetate, polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene, and perfluoroalkoxy fluororesins. , ethylene-tetrafluoroethylene copolymers, etc.), polyesters (e.g., polyethylene terephthalate, polyethylene naphthalate, polyethylene succinate, polybutylene succinate, polylactic acid, etc.), polylactones (e.g., polycaprolactone, etc.), polyamides or polyimides (e.g., nylon, polyamic acid, polyamideimide, aramid, etc.), polyurethanes, polyureas, polycarbonates, polyaromatics, polysulfones, polyethersulfones, polysiloxane derivatives (e.g., silicone rubber), polyketones, etc. From the viewpoints of solubility, strength, elasticity, etc., these may be homopolymers, copolymers, polymer blends, polymer alloys, or sintered bodies.

[0078] In addition, as the microstructured membrane, a nonwoven fabric in which fibers are oriented in one direction or randomly to form micropores (microspaces) between the fibers can be selected. Examples of nonwoven fabrics that can be used as the microstructured membrane include cellulose nanofibers, rayon, acrylic polymers, vinylon, carbon fibers, vinyl polymerization polymers (e.g., polyethylene, polypropylene, polystyrene, polyacrylate, polymethacrylate, polyacrylamide, polymethacrylamide, polyvinyl chloride, polyvinylidene chloride, polyvinylidene fluoride, polyhexafluoropropene, polyvinyl ether, polyvinylcarbazole, polyvinyl acetate, polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene, perfluoroalkoxy, etc.). Examples of the polymerizable material include polyolefin polymers such as poly(ethylene terephthalate), poly(ethylene naphthalate), poly(ethylene succinate), poly(butylene succinate), poly(lactic acid), poly(lactide), poly(lactone), poly(caprolactone), polyamide or polyimide (such as nylon, polyamic acid, polyamideimide, aramid), polyurethane, polyurea, polycarbonate, polyaromatics, polysulfone, polyethersulfone, polysiloxane derivatives (such as silicone rubber), polyketone, etc. From the viewpoints of solubility, strength, elasticity, etc., these may be homopolymers, copolymers, polymer blends, polymer alloys, or sintered bodies.

[0079] The resin film constituting the outer membrane portion 106 is made of a resin material. Examples of resin materials that can be used as the outer membrane portion 106 include silicone compounds, thermoplastic polymers, elastomers, and the like. It is preferable to use a resin material that does not decompose or is difficult to decompose in the body.

[0080] Resin materials that can be used as the outer membrane portion 106 include those that solidify from a molten liquid state, those that solidify from a plastic gel (or rubber) state, and those that are dissolved in a solvent and solidify when the solvent evaporates. When manufacturing the covered stent 100, a resin material in a molten, plastic, or solution state is placed (including applied) on the circumferential surface of the microstructure film that constitutes the inner membrane portion 104, and the resin material is allowed to penetrate into the recesses 105 on the circumferential surface of the microstructure film and then solidified, so that a part of the resin film that constitutes the outer membrane portion 106 can be solidified while penetrating into the recesses 105 on the circumferential surface of the microstructure film.

[0081] The resin material may be solidified over time by drying after being placed on the circumferential surface of the microstructure film, or may be solidified by a polymerization reaction using a polymerization initiator or a crosslinking reaction using a curing agent after being placed on the circumferential surface of the microstructure film, or may be solidified by volatilization of the solvent from a solution state in which the resin material is dissolved in a solvent. When performing the polymerization reaction or crosslinking reaction, the resin material may be solidified by mixing two liquids, for example, a main liquid (resin reaction liquid) and a catalyst (polymerization initiator or curing agent). If necessary, the resin material may be heated or irradiated with light when solidifying. However, it is preferable to select a resin material that does not require heating to a temperature higher than that which affects the material constituting the frame portion 102. For example, when the frame portion 102 is made of a nickel-titanium alloy, it is preferable to select a resin material that is solidified by heating to a temperature lower than 300°C because heating to a temperature higher than 300°C may change the properties of the nickel-titanium alloy.

[0082] Alternatively, a prepolymer may be used as the resin material, and the prepolymer may be polymerized and solidified to form the resin film. In this way, the prepolymer, which is the resin material, is placed on the peripheral surface of the frame portion 102, and then a polymerization initiator is used to cause a polymerization reaction, so that the resin material is solidified to form the resin film. The prepolymer refers to an intermediate product in the process of polymerizing a monomer, and includes monomers and oligomers.

[0083] Examples of prepolymers that can be used as the resin material include silicones (siloxanes (e.g., polydialkylsiloxane, polydimethylsiloxane), cyclic siloxanes (cyclopentanesiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, dimethylcyclosiloxane), silicone derivatives (e.g., trimethylsiloxysilicate, cetearylmethicone, dimethicone, dimethicone copolyol, cyclomethicone, simethicone)), diols (e.g., acetylene diol, alkane diol, and tetramethyldodecyne diol), and combinations thereof.

[0084] Silicone compounds suitable as resin materials can be used without any particular limitation as long as they have a polysiloxane structure, and examples thereof include silicone-modified resins, straight silicone oils, non-reactive modified silicone oils, and reactive modified silicone oils. Silicone compounds can be used alone or in combination of two or more. Silicone-modified resins used as silicone compounds are not particularly limited as long as they are resins modified with silicone. In addition, modified silicone oils used as silicone compounds are preferably polyether-modified silicones, alkyl-modified silicones, and epoxy-modified silicones.

[0085] Examples of thermoplastic polymers suitable for the resin material include vinyl polymers, polyurethanes, polyamides, polyetheramides, polyethers, polyesters, polylactones, and polyetherimides.

[0086] Furthermore, examples of elastomers suitable as the resin material include natural rubber, isoprene rubber, styrene-based elastomers, olefin-based elastomers, polyvinyl chloride (PVC)-based elastomers, ethylene vinyl acetate (EVA)-based elastomers, urethane-based elastomers, and ester-based elastomers.

[0087] The resin material may be solidified using a photopolymerization initiator. The photopolymerization initiator promotes the solidification of the resin material by irradiating it with light (e.g., ultraviolet light). As the photopolymerization initiator, it is preferable to use a substance whose safety to living organisms has been confirmed, and for example, Esacure (registered trademark) "KIP150" (substance name: oligomer of 2-hydroxy-1-(4-isopropenylphenyl)-2-methyl-1-propanone) approved by the U.S. Food and Drug Administration (FDA) can be suitably used.

[0088] As shown in the partially enlarged view of FIG. 2 (partially enlarged view with the symbol A), the microstructure film constituting the inner film portion 104 and the resin film constituting the outer film portion 106 have an interface where they are in contact with each other at least in part. At the interface, a large number of recesses 105 are formed on the circumferential surface (outer circumferential surface) of the microstructure film constituting the inner film portion 104, and a part of the resin film constituting the outer film portion 106 is solidified in a state in which it penetrates into the recesses 105 on the circumferential surface of the microstructure film, and the microstructure film and the resin film are integrated. This increases the contact area between the microstructure film and the resin film, thereby improving the adhesive strength between the microstructure film and the resin film. In addition, some of the recesses 105 on the circumferential surface of the microstructure film have a wider space on the inner side than the opening on the circumferential surface, and a part of the resin film that has penetrated into the space on the inner side of the recesses 105 and solidified is locked in a state in which it is difficult to get out of the recesses 105, and the adhesive strength can be improved by the anchor effect.

[0089] The microstructure film may have a large number of recesses 105 formed at the interface with the resin film. For example, a large number of micropores contained in the microstructure film are exposed and opened at the interface, forming a large number of recesses 105. Regarding the distribution of micropores (pore distribution) in the microstructure film, a large number of micropores may be distributed over the entire thickness direction of the microstructure film, or may be distributed only near the peripheral surface of the microstructure film (near the interface with the resin film). However, the greater the number of micropores (porosity) and the greater the distribution of micropores over the entire thickness direction of the microstructure film, the more flexible the microstructure film is, and the easier it is to process it into a shape that conforms to the peripheral surface of the frame part 102. Furthermore, a film with flat outer and inner surfaces may be prepared, and a large number of recesses 105 may be formed only on the outer surface by, for example, roughening, and the microstructure film with a large number of recesses 105 formed only on the outer surface may be used as the inner film part 104. In the present invention, the microstructure film means one in which a large number of recesses 105 are formed on the peripheral surface of the microstructure film into which a resin film can penetrate and become solidified. In particular, it is preferable to use a porous material or nonwoven fabric that contains a large number of micropores within the microstructure film and in which a large number of recesses 105 are formed by the large number of micropores being exposed and opened on the peripheral surface.

[0090] When the entire microstructure film is porous, has many micropores distributed throughout its thickness direction, and is connected to each other, the resin film can be solidified in a state in which it has penetrated into the interior of the microstructure film. In this case, the depth to which the resin film penetrates into the microstructure film is not particularly limited, but it is preferable that the resin film penetrates to about half the thickness of the microstructure film, and it is more preferable that the resin film penetrates the entire thickness of the microstructure film as shown in the enlarged partial view of FIG. 2 with the symbol B. When the resin film penetrates the entire thickness of the microstructure film, the surface of the microstructure film opposite to the surface in contact with the resin film (the inner surface of the microstructure film constituting the inner film portion 104) has a mottled surface in which the raw materials of the microstructure film and the raw materials of the resin film are finely mixed together. On the other hand, when the microstructure film has a large number of recesses 105 formed only on its outer peripheral surface by roughening or the like, the surface opposite to the surface of the microstructure film that is in contact with the resin film (the inner peripheral surface of the microstructure film that constitutes the inner membrane portion 104) becomes a flat surface in which the raw material of the resin film is not exposed.

[0091] Furthermore, the inner membrane portion 104 and the outer membrane portion 106 may be provided so as to cover the entire peripheral surface of the frame portion 102 in the circumferential direction, or may be provided so as to cover only a portion of the peripheral surface of the frame portion 102 in the circumferential direction.

[0092] 3 is a partial enlarged view of the region R2 in FIG. 2, where FIG. 3(a) is a view showing an example of the region R2 in FIG. 2, and FIG. 3(b) is a view showing another example of the region R2. For example, when the resin film constituting the outer membrane portion 106 is provided so as to cover the entire circumferential direction of the frame portion 102, as shown in FIG. 3(a), the circumferential surface of the wire material constituting the frame portion 102 is also covered with the resin film. On the other hand, as shown in FIG. 3(b), for example, a part of the circumferential surface of the wire material constituting the frame portion 102 may be exposed from the resin film constituting the outer membrane portion 106. In this case, the covered stent 100 has a covered region 110a covered with the resin film and a non-covered region 110b not covered with the resin film.

[0093] In the present invention, the inner membrane portion 104 or the outer membrane portion 106 covering at least a portion of the circumferential surface of the frame portion 102 includes both a state in which the inner membrane portion 104 or the outer membrane portion 106 covers only a portion of the circumferential surface of the frame portion 102, as in the covered region 108a and the uncovered region 108b shown in Figure 1, and a state in which the inner membrane portion 104 or the outer membrane portion 106 covers only a portion of the circumferential surface of the frame portion 102, as in the covered region 110a and the uncovered region 110b shown in Figure 3(b).

[0094] As described above, the covered stent 100 in the first embodiment of the present invention is covered by the inner membrane portion 104 covering the inner peripheral surface of the frame portion 102 and the outer membrane portion 106 covering the outer peripheral surface of the frame portion 102 so as to sandwich and cover the frame portion 102, and at the interface between the microstructure film constituting the inner membrane portion 104 and the resin film constituting the outer membrane portion 106, the resin film penetrates into the many recesses 105 formed on the peripheral surface (outer peripheral surface) of the microstructure film and is in a solidified state. This makes it possible to provide a covered stent 100 with excellent durability by suppressing peeling of the microstructure film and the resin film.

[0095] (Method of manufacturing the covered stent in the first embodiment) Hereinafter, an example of a method for manufacturing the covered stent 100 in the first embodiment of the present invention will be described with reference to Figs. 4 to 6. Fig. 4 is a flow chart showing an example of a method for manufacturing the covered stent 100 in the first embodiment of the present invention. Fig. 5 is a side view showing a mold member 200 used in an example of a method for manufacturing the covered stent 100 in the first embodiment of the present invention. Fig. 6 is a cross-sectional view showing a state near the outer circumferential surface of the cylindrical mold member 200 (region R3 in Fig. 5) for explaining an example of a method for manufacturing the covered stent 100 in the first embodiment of the present invention. In Fig. 6, the horizontal direction (direction indicated by arrow AX) on the paper surface corresponds to the axial direction, and the bottom to top direction (direction indicated by arrow D) on the paper surface corresponds to the radially outward direction.

[0096] When manufacturing the covered stent 100, first, a tubular frame portion 102 that serves as the skeleton of the covered stent 100 and is capable of expanding and deforming radially outward is prepared (step S210), and a mold member 200 having an outer peripheral surface (cylindrical surface) 201 that conforms to the frame portion 102 is prepared (step S220).

[0097] As the mold member 200, for example, a mandrel (core material) as shown in FIG. 5 can be used. The mold member 200 is formed in a cylindrical (rod-like) shape and has an outer circumferential surface (cylindrical surface) 201. The outer diameter of the mold member 200 is approximately the same as the inner diameter of the frame portion 102 in the expanded state, so that the mold member 200 can be inserted into the lumen of the frame portion 102. When manufacturing the covered stent 100, a process is performed in which the frame portion 102 is fitted to the outer circumferential side of the mold member 200, and the inner membrane portion 104 and the outer membrane portion 106 are provided on the frame portion 102 on the outer circumferential surface 201 of the mold member 200. The material constituting the mold member 200 is not particularly limited, but stainless steel can be used, for example.

[0098] Next, a microstructure film covering at least a portion of one of the inner and outer circumferential surfaces of the frame portion 102, a resin material covering at least a portion of the other of the inner and outer circumferential surfaces of the frame portion 102, and the frame portion 102 are arranged on the outer circumferential surface 201, which is the cylindrical surface of the cylindrical mold member 200 (Step S230: Arrange material).

[0099] The above step S230 is a process of arranging the microstructure film, the resin material, and the frame portion 102 on the outer circumferential surface 201 side of the mold member 200. Specifically, the process includes the following steps S231 to S234.

[0100] A fluorine-based coating agent is applied onto the outer circumferential surface 201 of the mold member 200 (step S231). By providing the fluorine-based coating agent between the mold member 200 and the microstructure film, the covered stent 100 can be easily removed from the mold member 200 in the final process (step S250).

[0101] A microstructure film is wound and arranged on the outer peripheral surface 201 coated with the fluorine-based coating agent (step S232). Here, as an example, a case where a film-like ePTFE is used as the microstructure film is described. ePTFE is a porous material, and many micropores are formed in the microstructure film, and many recesses 105 are formed on the outer peripheral surface by exposing and opening many micropores.

[0102] The mold member 200 is inserted into the lumen of the frame member 102, and the frame member 102 is disposed on the upper side (outer periphery side) of the microstructure film wrapped around the mold member 200 (step S233).

[0103] A resin material is applied from the upper side (outer periphery side) of the frame portion 102 (step S234). As an example, a case will be described in which a silicone compound is used as the resin material, and a mixture of two liquids, a silicone compound and a curing agent, is applied.

[0104] Through the above steps, the covered stent 100 (in the process of being manufactured) is placed on the outer circumferential surface 201 of the mold member 200 as shown in Fig. 5, and the microstructured film (ePTFE) constituting the inner membrane portion 104, the frame portion 102, and the resin material (silicone compound) constituting the outer membrane portion 106 are laminated in this order on the upper side (outer circumferential side) of the outer circumferential surface 201 of the mold member 200 located on the innermost side as shown in Fig. 6. The resin material applied from the upper side (outer circumferential side) of the frame portion 102 covers the outer circumferential side of the frame portion 102, and a part of it comes into contact with the outer circumferential surface of the microstructured film through the mesh formed in the frame portion 102.

[0105] Next, the resin material is solidified from a molten state, a plastic state, or a solution state to cover at least a part of the other surface, and a resin film is formed in a state where the resin material penetrates into the recesses 105 formed on the outer peripheral surface of the microstructure film and contacts the microstructure film. Specifically, the mold member 200 in a state where the microstructure film, the frame portion 102, and the resin material are laminated in this order toward the outer peripheral side is dried to a certain extent, and then heated at a predetermined temperature (e.g., 150°C) for a predetermined time using an oven or the like to solidify the resin material and form a resin film as the outer membrane portion 106 (step S240). Then, when the covered stent 100 is removed from the mold member 200 (step S250), a covered stent 100 in a state where the resin film constituting the outer membrane portion 106 penetrates and solidifies into the numerous recesses 105 formed on the outer peripheral surface of the microstructure film constituting the inner membrane portion 104 can be manufactured.

[0106] Here, the heat treatment is performed to solidify the mixture of two liquids, the silicone compound and the curing agent, but it is preferable to set the solidification process of the resin material appropriately depending on the selected resin material. In addition, in order to ensure that the resin material, which has become liquid or gelled and has fluidity, penetrates into the recesses 105 on the circumferential surface of the microstructure film at the interface where the microstructure film and the resin material contact each other, the liquid or gel resin material may be solidified under negative pressure. This allows air bubbles contained in the microstructure film to be removed, and the resin material with fluidity to penetrate into the inside of the microstructure film, thereby ensuring that the resin material penetrates into the many recesses 105 formed on the circumferential surface of the microstructure film.

[0107] (Covered stent in the second embodiment) A covered stent 100 according to a second embodiment of the present invention will be described below. Fig. 7 is a cross-sectional view of a covered stent according to a second embodiment of the present invention. Fig. 7 shows a cross-sectional view taken along line AA in Fig. 1, and a partially enlarged view showing the state of the vicinity of the interface between the microstructure film and the resin film (region R4).

[0108] 7, in the covered stent 100 in the second embodiment, the inner membrane portion 104 is composed of a resin film, and the outer membrane portion 106 is composed of a microstructure film, and the resin film constituting the inner membrane portion 104, the frame portion 102, and the microstructure film constituting the outer membrane portion 106 are laminated in this order toward the radially outer side of the tubular frame portion 102. That is, in the covered stent 100 in the second embodiment, the laminated order of the resin film, frame portion 102, and microstructure film is reversed compared to the above-mentioned first embodiment.

[0109] In the covered stent 100 of the first embodiment, a large number of recesses 105 are formed on the outer surface of the microstructure membrane, whereas in the covered stent 100 of the second embodiment, a large number of recesses 105 are formed on the inner surface of the microstructure membrane.

[0110] As shown in the partially enlarged view of FIG. 7 (partially enlarged view with the symbol A), the resin film constituting the inner film portion 104 and the micro-structure film constituting the outer film portion 106 have an interface where they are in contact with each other at least in part. At the interface, a large number of recesses 105 are formed on the circumferential surface (inner circumferential surface) of the micro-structure film constituting the outer film portion 106, and a part of the resin film constituting the inner film portion 104 is solidified in a state in which it penetrates into the recesses 105 on the circumferential surface of the micro-structure film, and the micro-structure film and the resin film are integrated. This increases the contact area between the micro-structure film and the resin film, thereby improving the adhesive strength between the micro-structure film and the resin film. In addition, some of the recesses 105 on the circumferential surface of the micro-structure film have a wider space on the inner side than the opening on the circumferential surface, and a part of the resin film that penetrates into the space on the inner side of the recesses 105 and solidifies is locked in a state in which it is difficult to get out of the recesses 105, and the adhesive strength can be improved by the anchor effect.

[0111] The microstructure film may have a large number of recesses 105 formed at the interface with the resin film. For example, a large number of micropores contained in the microstructure film are exposed and opened at the interface, forming a large number of recesses 105. Regarding the distribution of micropores (pore distribution) in the microstructure film, a large number of micropores may be distributed over the entire thickness direction of the microstructure film, or may be distributed only near the peripheral surface of the microstructure film (near the interface with the resin film). However, the greater the number of micropores (porosity) and the greater the distribution of micropores over the entire thickness direction of the microstructure film, the more flexible the microstructure film is, and the easier it is to process it into a shape that conforms to the peripheral surface of the frame part 102. Furthermore, a film with flat outer and inner surfaces may be prepared, and a large number of recesses 105 may be formed only on the inner surface by, for example, roughening, and the microstructure film with a large number of recesses 105 formed only on the inner surface may be used as the outer film part 106. In the present invention, the microstructure film means one in which a large number of recesses 105 are formed on the peripheral surface of the microstructure film into which a resin film can penetrate and become solidified. In particular, it is preferable to use a porous material or nonwoven fabric that contains a large number of micropores within the microstructure film and in which a large number of recesses 105 are formed by the large number of micropores being exposed and opened on the peripheral surface.

[0112] When the entire microstructure film is porous, has many micropores distributed throughout its thickness direction, and is connected to each other, the resin film can be solidified in a state in which it has penetrated into the interior of the microstructure film. In this case, the depth to which the resin film penetrates into the microstructure film is not particularly limited, but it is preferable that the resin film penetrates to about half the thickness of the microstructure film, and it is even more preferable that the resin film penetrates the entire thickness of the microstructure film, as shown in the enlarged partial view of FIG. 7 with the symbol B. When the resin film penetrates the entire thickness of the microstructure film, the surface of the microstructure film opposite to the surface in contact with the resin film (the outer peripheral surface of the microstructure film constituting the outer film portion 106) has a mottled surface in which the raw materials of the microstructure film and the raw materials of the resin film are finely mixed together. On the other hand, when the microstructure film has a large number of recesses 105 formed only on its inner surface by roughening or the like, the surface opposite to the surface of the microstructure film that is in contact with the resin film (the outer surface of the microstructure film that constitutes the outer film portion 106) becomes a flat surface in which the raw material of the resin film is not exposed.

[0113] The resin film, frame 102, and microstructure film of the covered stent 100 in the second embodiment are similar to those in the first embodiment, and detailed description thereof will be omitted here. As in the first embodiment, the resin material constituting the resin film and the method for solidifying the selected resin material may be appropriately selected as necessary.

[0114] As described above, the covered stent 100 in the second embodiment of the present invention is covered by the inner membrane portion 104 covering the inner peripheral surface of the frame portion 102 and the outer membrane portion 106 covering the outer peripheral surface of the frame portion 102 so as to sandwich and cover the frame portion 102, and at the interface between the resin film constituting the inner membrane portion 104 and the microstructure film constituting the outer membrane portion 106, the resin film penetrates into the many recesses 105 formed on the peripheral surface (inner peripheral surface) of the microstructure film and is in a solidified state. This makes it possible to provide a covered stent 100 with excellent durability by suppressing peeling of the microstructure film and the resin film.

[0115] (Method of manufacturing the covered stent in the second embodiment) Hereinafter, an example of a method for manufacturing the covered stent 100 in the second embodiment of the present invention will be described with reference to Fig. 8 and Fig. 9. Fig. 8 is a flow chart showing an example of a method for manufacturing the covered stent 100 in the second embodiment of the present invention. Fig. 9 is a cross-sectional view showing a state near the outer circumferential surface of the cylindrical mold member 200 (region R3 in Fig. 5) for explaining an example of a method for manufacturing the covered stent 100 in the second embodiment of the present invention. In Fig. 9, the horizontal direction (direction indicated by arrow AX) on the paper corresponds to the axial direction, and the bottom-to-top direction (direction indicated by arrow D) on the paper corresponds to the radially outward direction.

[0116] When manufacturing the covered stent 100, first, a tubular frame portion 102 that serves as the skeleton of the covered stent 100 and is capable of expanding and deforming radially outward is prepared (step S310), and a mold member 200 having an outer peripheral surface (cylindrical surface) 201 that conforms to the frame portion 102 is prepared (step S320).

[0117] As in the first embodiment described above, for example, a core material (mandrel) as shown in Fig. 5 can be used as the mold member 200. When manufacturing the covered stent 100, a step is performed in which the frame portion 102 is fitted to the outer periphery of the mold member 200, and the inner membrane portion 104 and the outer membrane portion 106 are provided on the frame portion 102 on the outer periphery 201 of the mold member 200.

[0118] Next, a microstructure film covering at least a portion of one of the inner and outer circumferential surfaces of the frame portion 102, a resin material covering at least a portion of the other of the inner and outer circumferential surfaces of the frame portion 102, and the frame portion 102 are arranged on the outer circumferential surface 201, which is the cylindrical surface of the cylindrical mold member 200 (Step S330: Arrange material).

[0119] The above step S330 is a process of arranging the microstructure film, the resin material, and the frame portion 102 on the outer circumferential surface 201 side of the mold member 200. Specifically, the process includes the following steps S331 to S334.

[0120] A fluorine-based coating agent is applied onto the outer peripheral surface 201 of the mold member 200 (step S331). By providing the fluorine-based coating agent between the mold member 200 and the resin material, the covered stent 100 can be easily removed from the mold member 200 in the final process (step S350).

[0121] A resin material is applied onto the outer peripheral surface 201 to which the fluorine-based coating agent has been applied (step S332). As an example, a case will be described in which a silicone compound is used as the resin material, and a mixture of two liquids, a silicone compound and a curing agent, is applied.

[0122] The mold member 200 is inserted into the lumen of the frame member 102, and the frame member 102 is placed on the upper side (outer periphery side) of the silicone compound applied to the mold member 200 (step S333).

[0123] The microstructure membrane is wound around the upper side (outer periphery) of the frame part 102 (step S334). Here, as an example, a case where a film-like ePTFE is used as the microstructure membrane is described. ePTFE is a porous material, and many micropores are formed in the microstructure membrane. On the inner periphery, many recesses 105 are formed by exposing and opening many micropores.

[0124] Through the above steps, the covered stent 100 (in the process of being manufactured) is placed on the outer circumferential surface 201 of the mold member 200 as shown in Fig. 5, and the resin material (silicone compound) constituting the inner membrane portion 104, the frame portion 102, and the microstructured film (ePTFE) constituting the outer membrane portion 106 are laminated in this order on the upper side (outer circumferential side) of the outer circumferential surface 201 of the mold member 200 located at the innermost position as shown in Fig. 9. The resin material arranged on the lower side (inner circumferential side) of the frame portion 102 covers the inner circumferential side of the frame portion 102, and a part of it comes into contact with the inner circumferential surface of the microstructured film through the mesh formed in the frame portion 102.

[0125] Next, the resin material is solidified from a molten state, a plastic state, or a solution state to cover at least a part of the other surface, and a resin film is formed in a state where the resin material penetrates into the recesses 105 formed on the inner peripheral surface of the microstructure film and contacts the microstructure film. Specifically, the mold member 200 in a state where the resin material, the frame portion 102, and the microstructure film are laminated in this order toward the outer peripheral side is dried to a certain extent, and then heated at a predetermined temperature (e.g., 150°C) using an oven or the like for a predetermined time to solidify the resin material, thereby forming a resin film as the inner membrane portion 104 (step S340). Then, when the covered stent 100 is removed from the mold member 200 (step S350), a covered stent 100 in a state where the resin film constituting the inner membrane portion 104 penetrates into the many recesses 105 formed on the inner peripheral surface of the microstructure film constituting the outer membrane portion 106 and is solidified can be manufactured.

[0126] As in the manufacturing method of the covered stent 100 in the first embodiment, in the example of the manufacturing method of the covered stent 100 in the second embodiment, it is preferable to appropriately set the solidification process of the resin material depending on the selected resin material, and the liquid or gel-like resin material may be solidified under negative pressure.

[0127] In one example of a method for manufacturing the covered stent 100 in the second embodiment described above, it is necessary to apply a resin material to the outer circumferential surface 201 of the cylindrical mold member 200, and then laminate the frame portion 102 and the microstructure film, and then make the resin material liquid or rubber-like. For this reason, a cylindrical (pipe-shaped) mold member 210 shown in Fig. 11 may be used so that the resin material can be applied from above after the microstructure film and the frame portion 102 are laminated.

[0128] Hereinafter, another example of the method for manufacturing the covered stent 100 according to the second embodiment of the present invention will be described with reference to Figs. 10 to 12. Fig. 10 is a flow chart showing another example of the method for manufacturing the covered stent 100 according to the second embodiment of the present invention. Fig. 11 is a side view showing a mold member 210 used in another example of the method for manufacturing the covered stent 100 according to the second embodiment of the present invention. Fig. 12 is a diagram for explaining another example of the method for manufacturing the covered stent 100 according to the second embodiment of the present invention, and is a cross-sectional view showing a state near the inner circumferential surface of the cylindrical mold member 210 (region R5 in Fig. 11). In Fig. 12, the horizontal direction (direction indicated by arrow AX) on the paper surface corresponds to the axial direction, and the bottom to top direction (direction indicated by arrow D) on the paper surface corresponds to the radially outward direction.

[0129] When manufacturing the covered stent 100, first, a tubular frame portion 102 that serves as the skeleton of the covered stent 100 and is capable of expanding and deforming radially outward is prepared (step S410), and a mold member 210 having an inner surface (cylindrical surface) 211 that conforms to the frame portion 102 is prepared (step S420).

[0130] Here, as the mold member 210, for example, a pipe-shaped member as shown in FIG. 10 can be used. The mold member 210 is formed in a cylindrical (pipe-shaped) shape having a lumen extending in the axial direction, and has an inner peripheral surface (cylindrical surface) 211. The inner diameter of the mold member 210 is approximately the same as the outer diameter of the frame portion 102 in the expanded state, so that the frame portion 102 can be inserted into the lumen of the mold member 210. When manufacturing the covered stent 100, a process is performed in which the frame portion 102 is fitted to the inner peripheral side of the mold member 210, and the inner membrane portion 104 and the outer membrane portion 106 are provided on the frame portion 102 on the inner peripheral surface 211 of the mold member 210. The material constituting the mold member 210 is not particularly limited, but stainless steel can be used, for example.

[0131] Next, a microstructure film covering at least a portion of one of the inner and outer circumferential surfaces of the frame portion 102, a resin material covering at least a portion of the other of the inner and outer circumferential surfaces of the frame portion 102, and the frame portion 102 are arranged on the inner circumferential surface 211, which is the cylindrical surface of the cylindrical mold member 210 (Step S430: Arrange material).

[0132] The above step S430 is a process of arranging the microstructure film, the resin material, and the frame portion 102 on the inner circumferential surface 211 side of the mold member 210. Specifically, the process includes the following steps S431 to S434.

[0133] A fluorine-based coating agent is applied onto the inner circumferential surface 211 of the mold member 210 (step S431). By providing the fluorine-based coating agent between the mold member 210 and the microstructure film, the covered stent 100 can be easily removed from the mold member 210 in the final process (step S450).

[0134] A microstructure membrane is wound and disposed on the inner circumferential surface 211 to which the fluorine-based coating agent has been applied (step S432). Here, as an example, a case where a film-like ePTFE is used as the microstructure membrane is described. ePTFE is a porous material, and many micropores are formed in the microstructure membrane, and many recesses 105 are formed on the inner circumferential surface by exposing and opening many micropores.

[0135] The frame portion 102 is inserted into the lumen of the mold member 210, and the frame portion 102 is disposed on the upper side (inner circumference side) of the microstructure film wrapped around the mold member 210 (step S433).

[0136] A resin material is applied from the upper side (inner periphery side) of the frame portion 102 (step S434). As an example, a case will be described in which a silicone compound is used as the resin material, and a mixture of two liquids, a silicone compound and a curing agent, is applied.

[0137] By the above process, as shown in Fig. 11, the covered stent 100 (in the process of being manufactured) is placed on the inner circumferential surface 211 of the mold member 210, and as shown in Fig. 12, the microstructured film (ePTFE) constituting the outer membrane portion 106, the frame portion 102, and the resin material (silicone compound) constituting the inner membrane portion 104 are laminated in this order on the upper side (inner circumferential side) of the inner circumferential surface 211 of the mold member 210 located on the outermost side. The resin material applied from the upper side (inner circumferential side) of the frame portion 102 covers the inner circumferential side of the frame portion 102, and a part of it comes into contact with the inner circumferential surface of the microstructured film through the mesh formed in the frame portion 102.

[0138] Next, the resin material is solidified from a molten state, a plastic state, or a solution state to cover at least a part of the other surface, and a resin film is formed in a state where the resin material penetrates into the recesses 105 formed on the inner peripheral surface of the microstructure film and contacts the microstructure film. Specifically, the mold member 210 in which the resin material, the frame portion 102, and the microstructure film are laminated in this order toward the outer peripheral side is dried to a certain extent, and then heated at a predetermined temperature (e.g., 150°C) for a predetermined time using an oven or the like to solidify the resin material and form a resin film as the inner membrane portion 104 (step S440). Then, when the covered stent 100 is removed from the mold member 210 (step S450), a covered stent 100 can be manufactured in a state where the resin film constituting the inner membrane portion 104 penetrates and solidifies into the numerous recesses 105 formed on the inner peripheral surface of the microstructure film constituting the outer membrane portion 106.

[0139] As in the method for manufacturing the covered stent 100 in the first embodiment, in the alternative example of the method for manufacturing the covered stent 100 in the second embodiment, it is preferable to appropriately set the solidification process of the resin material depending on the selected resin material, and the liquid or gel-like resin material may be solidified under negative pressure.

[0140] Hereinafter, the operation of the covered stent 100 and the method of manufacturing the covered stent 100 in the above-described first and second embodiments will be described.

[0141] The covered stent 100 in the first and second embodiments described above is configured to include a tubular frame portion 102 capable of expanding and deforming radially outward, an inner membrane portion 104 covering at least a part of the inner peripheral surface of the frame portion 102, and an outer membrane portion 106 covering at least a part of the outer peripheral surface of the frame portion 102 and contacting the inner membrane portion 104. This covered stent 100 is characterized in that one of the inner membrane portion 104 and the outer membrane portion 106 is made of a microstructure film having a number of recesses 105 formed on its peripheral surface, and the other of the inner membrane portion 104 and the outer membrane portion 106 is made of a resin film made of a resin material, and at the interface where the resin film and the microstructure film contact each other, the resin material constituting the resin film penetrates into the recesses 105 of the microstructure film.

[0142] According to the above configuration, a large number of recesses 105 are formed on the peripheral surface of the microstructure film that comes into contact with the resin film, and the resin material that constitutes the resin film penetrates into the recesses 105 of the microstructure film, thereby improving the adhesive strength between the microstructure film and the resin film and integrating them. This makes it possible to provide a covered stent 100 with excellent durability by suppressing peeling of the microstructure film and the resin film that cover the frame portion 102 in a sandwiching manner on the inner and outer peripheral surfaces of the frame portion 102.

[0143] In the covered stent 100 in the above-described first and second embodiments, in the above configuration, the microstructure film may be made of a porous material or nonwoven fabric containing a large number of micropores.

[0144] According to the above configuration, by selecting a porous material or nonwoven fabric containing a large number of micropores as the material for the microstructure film, it is possible to easily and reliably select a microstructure film having recesses 105 formed on its peripheral surface by a large number of micropores.

[0145] In the covered stent 100 in the above-described first and second embodiments, in the above-described configuration, the resin material may be a silicone compound, a thermoplastic polymer, or an elastomer.

[0146] According to the above-mentioned configuration, it is possible to easily and reliably select a resin material that has the property of solidifying from a molten state, a plastic state, or a solution state.

[0147] In the covered stent 100 in the first and second embodiments described above, in the above configuration, the resin material may have the property of solidifying from a molten state, plastic state, or solution state after being placed on the inner or outer surface of the frame portion 102.

[0148] According to the above configuration, a resin material in a molten, plastic or solution state can be placed on the inner or outer peripheral surface of the frame portion 102, and the resin material can be solidified while penetrating the recesses 105 of the microstructure film to form a resin film.

[0149] In the covered stent 100 in the first and second embodiments described above, in the above configuration, the resin material may contain a resin reaction liquid that reacts with a polymerization initiator or a curing agent and solidifies.

[0150] According to the above configuration, a resin material containing a resin reaction liquid as a main liquid is applied onto the inner or outer peripheral surface of the frame portion 102, and the resin material is solidified by causing a polymerization reaction or a cross-linking reaction using a polymerization initiator or a curing agent, thereby forming a resin film.

[0151] In the covered stent 100 in the first and second embodiments described above, in the above configuration, the resin film may be formed by polymerizing and solidifying a prepolymer, which is a resin material.

[0152] According to the above configuration, a prepolymer, which is a resin material, is placed on the inner or outer peripheral surface of the frame portion 102, and then a polymerization reaction is caused by a polymerization initiator, so that the resin material can be solidified to form a resin film.

[0153] In the covered stent 100 in the first and second embodiments described above, in the above configuration, the prepolymer may contain a monomer.

[0154] According to the above configuration, by forming the prepolymer from a monomer before the polymerization reaction, the prepolymer resin material can be placed on the inner or outer peripheral surface of the frame portion 102, and then the resin material can be solidified by a polymerization reaction to form a resin film.

[0155] In the covered stent 100 in the first and second embodiments described above, in the above configuration, the resin material may be in a state in which it has permeated into the recesses 105 formed in the microstructure film.

[0156] According to the above configuration, the resin material in a molten, plastic or solution state is allowed to penetrate into the recesses 105 formed in the microstructure film and solidify, so that the resin film and the microstructure film are bonded together while the resin material is infiltrated into the microstructure film, improving the adhesive strength between the microstructure film and the resin film. In particular, the resin material in a molten or solution state is in a liquid state and therefore easily penetrates into the microstructure film, which is expected to improve the adhesive strength between the microstructure film and the resin film.

[0157] As in the covered stent 100 in the first embodiment described above, in the above configuration, the inner membrane portion 104 may be made of a microstructure film, and the outer membrane portion 106 may be made of a resin film.

[0158] According to the above-mentioned configuration, it is possible to provide a covered stent 100 in which a microstructure film, a frame portion 102, and a resin film are laminated in this order from the inner periphery side.

[0159] As in the covered stent 100 in the second embodiment described above, in the above configuration, the inner membrane portion 104 may be made of a resin film, and the outer membrane portion 106 may be made of a microstructure film.

[0160] According to the above-mentioned configuration, it is possible to provide a covered stent 100 in which the resin film, the frame portion 102, and the microstructure film are laminated in this order from the inner periphery side.

[0161] The covered stent 100 in the above-described first and second embodiments may be a digestive stent that is placed in a digestive organ.

[0162] According to the above configuration, it is possible to provide a covered stent 100 having excellent durability and usable as a digestive stent to be placed in an organ of the digestive system.

[0163] The covered stent 100 in the above-described first and second embodiments may be a circulatory stent that is placed in a circulatory system organ in the above-described configuration.

[0164] According to the above configuration, it is possible to provide a covered stent 100 having excellent durability and usable as a digestive stent to be placed in a circulatory system organ.

[0165] In order to achieve the above-mentioned object, the manufacturing method of the covered stent 100 according to the first and second embodiments is characterized by comprising the steps of: preparing a tubular frame portion 102 constituting the covered stent 100, which can be deformed by expanding radially outward; preparing mold members 200, 210 having a cylindrical surface along the frame portion 102; arranging, on the cylindrical surfaces of the mold members 200, 210, a microstructure film covering at least a part of one of the inner and outer circumferential surfaces of the frame portion 102 and having a number of recesses 105 formed on its circumferential surface; a resin material covering at least a part of the other of the inner and outer circumferential surfaces of the frame portion 102; and the frame portion 102; and solidifying the resin material from a molten, plastic or solution state to form a resin film that covers at least a part of the other surface and contacts the microstructure film in a state in which the resin material penetrates into the recesses 105 of the microstructure film.

[0166] According to the above process, numerous recesses 105 are formed by micropores on the peripheral surface of the microstructure film that contacts the resin film, and the resin material that constitutes the resin film penetrates into the recesses 105 of the microstructure film, thereby improving the adhesive strength between the microstructure film and the resin film and integrating them. This suppresses peeling of the microstructure film and the resin film that cover the frame portion 102 in a sandwiching manner on the inner and outer peripheral surfaces of the frame portion 102, thereby providing a covered stent 100 with excellent durability.

[0167] In the above-described manufacturing method of the covered stent 100 according to the first and second embodiments, the microstructure film may be made of a porous material or nonwoven fabric containing a large number of micropores.

[0168] According to the above process, by selecting a porous material or nonwoven fabric containing a large number of micropores as the material for the microstructure film, it is possible to easily and reliably select a microstructure film having a recess 105 formed on its peripheral surface by a large number of micropores.

[0169] In the manufacturing method of the covered stent 100 according to the first and second embodiments described above, the resin material may be a silicone compound, a thermoplastic polymer, or an elastomer in the above steps.

[0170] According to the above process, it is possible to easily and reliably select a resin material that has the property of solidifying from a molten state, a plastic state, or a solution state.

[0171] In the manufacturing method of the covered stent 100 according to the first and second embodiments described above, in the above steps, a resin material in a molten state, plastic state or solution state may be placed on the inner or outer surface of the frame portion 102 and solidified.

[0172] According to the above process, a resin material in a molten, plastic or solution state can be placed on the inner or outer peripheral surface of the frame portion 102, and the resin material can be solidified while penetrating the recesses 105 of the microstructure film to form a resin film.

[0173] In the manufacturing method of the covered stent 100 according to the first and second embodiments described above, in the above steps, the resin material contains a resin reaction liquid that reacts with a polymerization initiator or a curing agent to solidify, and the resin reaction liquid may be solidified by a reaction with the polymerization initiator or the curing agent.

[0174] According to the above process, a resin material containing a resin reaction liquid as a main liquid is applied onto the inner or outer peripheral surface of the frame portion 102, and the resin material is solidified by causing a polymerization reaction or a cross-linking reaction using a polymerization initiator or a curing agent, thereby forming a resin film.

[0175] In the manufacturing method of the covered stent 100 according to the first and second embodiments described above, a prepolymer may be used as the resin material in the above steps, and the resin film may be formed by polymerizing and solidifying the prepolymer.

[0176] According to the above process, a prepolymer, which is a resin material, is placed on the inner or outer peripheral surface of the frame portion 102, and then a polymerization reaction is caused by a polymerization initiator, so that the resin material can be solidified to form a resin film.

[0177] In the above-described manufacturing method of the covered stent 100 according to the first and second embodiments, the prepolymer may contain a monomer in the above steps.

[0178] According to the above process, by forming the prepolymer from a monomer prior to the polymerization reaction, the prepolymer resin material can be placed on the inner or outer peripheral surface of the frame portion 102, and then the resin material can be solidified by a polymerization reaction to form a resin film.

[0179] In the manufacturing method of the covered stent 100 according to the first and second embodiments described above, in the above steps, a resin material in a molten state, a plastic state, or a solution state may be permeated into the recesses 105 formed in the microstructure film.

[0180] According to the above process, the resin material in a molten, plastic or solution state is allowed to penetrate into the recesses 105 formed in the microstructure film and solidify, so that the resin film and the microstructure film are bonded together while the resin material is infiltrated into the microstructure film, improving the adhesive strength between the microstructure film and the resin film. In particular, the resin material in a molten or solution state is in a liquid state and therefore easily penetrates into the microstructure film, which is expected to improve the adhesive strength between the microstructure film and the resin film.

[0181] In the manufacturing method of the covered stent 100 according to the first and second embodiments described above, in the above steps, a resin material in a molten state, a plastic state or a solution state may be infiltrated into the recesses 105 formed in the microstructure film under negative pressure.

[0182] According to the above process, air bubbles contained in the microstructure film can be removed, and the resin material in a molten, plastic or liquid state can be reliably permeated into the interior of the microstructure film.

[0183] As in the manufacturing method of the covered stent 100 according to the first embodiment described above, in the above steps, a microstructure film, a frame portion 102, and a resin material may be arranged in that order on the outer peripheral surface 201 of a cylindrical mold member 200, thereby manufacturing a covered stent 100 in which a microstructure film is formed on the inner peripheral surface of the frame portion 102 and a resin film is formed on the outer peripheral surface of the frame portion 102.

[0184] According to the above process, it is possible to provide a covered stent 100 in which the microstructure film, the frame portion 102, and the resin film are laminated in this order from the inner periphery side.

[0185] As in the manufacturing method of the covered stent 100 according to the second embodiment described above, in the above steps, the microstructure film, the frame portion 102, and the resin material may be arranged in that order on the inner surface 211 of the cylindrical mold member 210, thereby manufacturing a covered stent 100 in which a microstructure film is formed on the outer surface of the frame portion 102 and a resin film is formed on the inner surface of the frame portion 102.

[0186] According to the above process, it is possible to provide a covered stent 100 in which the resin film, the frame portion 102, and the microstructure film are laminated in this order from the inner periphery side.

[0187] In the manufacturing method of the covered stent 100 according to the first and second embodiments described above, a digestive stent to be placed in a digestive organ may be manufactured as the covered stent 100 in the above steps.

[0188] According to the above process, it is possible to provide a covered stent 100 having excellent durability and usable as a digestive stent to be placed in an organ of the digestive system.

[0189] In the manufacturing method of the covered stent 100 according to the first and second embodiments described above, a circulatory stent to be placed in a circulatory system organ may be manufactured as the covered stent 100 in the above steps.

[0190] According to the above process, it is possible to provide a covered stent 100 having excellent durability and usable as a digestive stent to be placed in a circulatory system organ.

[0191] The above-described embodiments are described to facilitate understanding of the present invention, and are not intended to limit the present invention. The components disclosed in the above-described embodiments are intended to include all design modifications and equivalents that fall within the technical scope of the present invention. Furthermore, configurations obtained by appropriately combining the components described in each embodiment are also included in the present invention.

[0192] For example, in the second embodiment of the present invention, another example of a manufacturing method for manufacturing a covered stent 100 using a cylindrical mold member 210 is described, but the covered stent 100 in the first embodiment of the present invention may also be manufactured using a cylindrical mold member 210 in a similar manner. [Explanation of symbols]

[0193] 100 Covered stent 102 Frame section 102a Strut 102b Bridge 104 Endometrium 105 Recess 106 Adventitial part 108a, 110a Coverage area 108b, 110b Uncoated areas 110b Uncoated area 200, 210 type parts 201 Outer surface (cylindrical surface) 211 Inner surface (cylindrical surface)

Claims

1. A covered stent comprising a tubular frame portion capable of being expanded and deformed radially outward, an inner membrane portion covering at least a part of the inner circumferential surface of the frame portion, and an outer membrane portion covering at least a part of the outer circumferential surface of the frame portion and in contact with the inner membrane portion, one of the inner membrane portion and the outer membrane portion is made of a microstructured membrane having a number of recesses formed on its circumferential surface, and the other of the inner membrane portion and the outer membrane portion is made of a resin membrane made of a resin material; A covered stent characterized in that at the interface where the resin film and the microstructure film contact each other, the resin material constituting the resin film has penetrated into the recesses of the microstructure film.

2. 2. The covered stent according to claim 1, wherein the inner membrane portion is made of the microstructured membrane, and the outer membrane portion is made of the resin membrane.

3. 2. The covered stent according to claim 1, wherein the inner membrane portion is made of the resin film, and the outer membrane portion is made of the microstructure film.

4. A method for manufacturing a covered stent, comprising: preparing a cylindrical frame portion that constitutes the covered stent and that is capable of being expanded and deformed radially outward; preparing a mold member having a cylindrical surface along the frame portion; a step of arranging, on a cylindrical surface of the mold member, a microstructure film covering at least a portion of one of the inner and outer peripheral surfaces of the frame part, the microstructure film having a number of recesses formed on the peripheral surface, a resin material covering at least a portion of the other of the inner and outer peripheral surfaces of the frame part, and the frame part; and solidifying the resin material from a molten, plastic, or solution state to form a resin film that covers at least a portion of the other surface and contacts the microstructure film with the resin material penetrating the recesses of the microstructure film.

5. 5. The method for manufacturing a covered stent according to claim 4, characterized in that the microstructure film, the frame portion, and the resin material are arranged in that order on the outer peripheral surface of the cylindrical mold member, thereby manufacturing the covered stent in which the microstructure film is formed on the inner peripheral surface of the frame portion and the resin film is formed on the outer peripheral surface of the frame portion.

6. 5. The method for manufacturing a covered stent according to claim 4, characterized in that the microstructure film, the frame portion, and the resin material are arranged in that order on the inner surface of the cylindrical mold member, thereby manufacturing the covered stent in which the microstructure film is formed on the outer surface of the frame portion and the resin film is formed on the inner surface of the frame portion.

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