JP2005052419A - Stent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stent with a reduced possibility of growth of a thrombus by coating the outer and inner surfaces with a polymer film which can flexibly follow the deformation and expansion of a stent body. <P>SOLUTION: The stent 1 comprises the stent body 10 made of an expansible tubular mesh, a cylindrical outer polymer film 2 layered on the outer surface of the stent body 10, and a cylindrical inner polymer film 3 layered on the inner surface of the stent body. The outer polymer film 2 and the inner polymer film 3 are not bonded to the stent body 10, but bonded to each other in a mesh section 1B of the meshed stent body 10. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a stent (intraluminal graft) used in recent years for endovascular therapy and surgery, in particular, stenotic coronary artery, stenotic carotid artery, bile duct, esophageal dilatation, and aneurysm occlusion. Specifically, the present invention relates to a stent in which an outer peripheral surface and an inner peripheral surface of a stent main body made of a tubular mesh capable of expanding diameter are covered with a polymer film.

  Traditionally, treatment of ischemic heart disease is percutaneous transluminal coronary angioplasty (PTCA), which means that a balloon catheter is transported through a lumen in a blood vessel, for example, to a stenotic site, and then the balloon is expanded with a fluid such as saline. The method of letting it be treated is common. However, with this method, there is a high probability that coronary occlusion in the acute phase and re-stenosis (so-called restenosis) at the site where PTCA is performed occur. In order to solve these problems, an intraluminal graft called a stent has been developed and recently put into practical use and has become widespread. Recent data show that nearly 75% of balloon catheter surgery has already been replaced by stent surgery.

  The stent body is an intraluminal graft that is carried through the inside of a lumen such as a blood vessel and supported by an action from the inside by expanding its diameter at the treatment site of the lumen. Although it is mainly used in the above-mentioned coronary artery surgery, it is mainly described here, but the stent is a ureter, ureter, fallopian tube, aortic aneurysm, peripheral artery, renal artery, carotid artery, It can also be used for other luminal parts of the human body such as cerebral blood vessels. Therefore, in the future, the field of use of stents will expand more and more, and stents will be used in many surgeries, especially in the field of neurosurgery, to cover even the smallest diameter, high flexibility and flexibility It is anticipated that it will be important to be able to pass through a bent vessel.

  Restenosis can be drastically prevented by the spread of surgery using stents. However, since the metallic stent body is a foreign substance in the body, thrombosis develops within a few weeks after insertion of the stent body. This is because the metal stent itself is exposed to blood, causing not only the adsorption of plasma proteins such as fibrinogen, adhesion of platelets, and aggregation, but also thrombus formation. There may be blood clots. In addition, thickening of the intima caused by cytokines released from platelets aggregated around the metal stent body has been pointed out as a problem.

  Japanese Patent Laid-Open No. 11-299901 describes a stent 20 in which the outer peripheral surface of a metal stent body is covered with a flexible polymer film 19 having fine holes, as shown in FIGS. . FIG. 4 shows a state where the diameter of the stent 20 is expanded.

  In living tissue, inner surfaces such as blood vessels, that is, portions that come into contact with blood are covered with a cell layer called endothelial cells. Since the surface of these endothelial cells is covered with sugar and the endothelial cells themselves secrete substances that suppress platelet activation such as prostaglandins, thrombus and the like are unlikely to occur in living tissues. The stent 20 described in Japanese Patent Application Laid-Open No. 11-299901 includes a polymer film 19 that is substantially uniformly perforated on the outer peripheral surface of a metal stent body, thereby covering the polymer film with an appropriate amount of vascular endothelial cells. The purpose is to promote engraftment and to reduce the thrombogenicity.

The applicant of the present invention is a stent in which thrombus generation is further reduced and intimal thickening is remarkably suppressed as compared with the stent of JP-A-11-299901. A patent application was previously filed for a stent coated with a flexible polymer film having a plurality of micropores (Japanese Patent Application No. 2002-243871). In the case of the stent of this Japanese Patent Application No. 2002-243871, since not only the outer peripheral surface of the stent body but also the inner peripheral surface is covered with a flexible polymer film, the metal material does not come into contact with blood, Since the surface becomes a smooth surface by the polymer film, the generation of thrombus can be suppressed more reliably.
JP 11-299901 A Japanese Patent Application No. 2002-243871

  In recent years, the field of application of stents has further expanded, and the stent body can be made of a flexible, shape-memory material that can be deformed into an arcuate shape to pass through a bent vessel or even be placed in place. The stent body is required to be deformed and expanded in diameter by following the shape of the vascular region to be sought (such as a region bent into an arcuate shape), and a stent body that can be expanded by being deformed into an arcuate shape has been developed. .

  However, in a stent that is covered with a flexible polymer film that is completely adhered to both the inner and outer circumferences of the stent body, the polymer film is twisted during expansion of the stent body, causing problems such as wrinkles and tearing. There is. In particular, in a stent body that is geometrically deformed and expands in the radial direction, this problem is significant when the deformation of the stent body is complicated or the degree of deformation is large.

  Therefore, an object of the present invention is to provide a stent in which the polymer film covering the stent body can flexibly follow the deformation and expansion of the stent body.

  The stent of the present invention includes a stent body made of an expandable tubular mesh, a cylindrical outer polymer film overlapping the outer peripheral surface of the stent main body, and a cylindrical inner polymer film overlapping the inner peripheral surface of the stent main body. The outer polymer film and the inner polymer film are non-adhered to the stent body, and are adhered to each other at least in a mesh portion of the mesh stent body. It is characterized by being.

  In the stent of the present invention, since the outer polymer film and the inner polymer film covering the stent body are not bonded to the stent body, the outer polymer film and the inner polymer film are displaced from each other when the stent body is expanded. During movement and stent expansion, the stent body expands while sliding between the outer polymer film and the inner polymer film, so that the polymer film does not twist or tear. Further, since the outer polymer film and the inner polymer film are bonded to each other in the mesh portion of the mesh-shaped stent body, the inner polymer film is pulled by the bonded portion when the stent is expanded, thereby following the entire expansion. Therefore, in any stent body of any structure, the outer peripheral surface and inner peripheral surface can be covered with a polymer film to reduce thrombus generation, and good flexibility, vessel followability, and flexibility can be obtained. .

  ADVANTAGE OF THE INVENTION According to this invention, the stent which coat | covered the outer peripheral surface and the inner peripheral surface with the polymer film, and reduced thrombus generation | occurrence | production, Comprising: The stent which can follow a deformation | transformation and expansion of any stent main body flexibly is provided.

  Hereinafter, embodiments will be described with reference to the drawings. FIG. 1A is a perspective view showing an embodiment of the stent of the present invention, FIG. 1B is an enlarged view of a cross section taken along line BB in FIG. 1A, and FIG. It is sectional drawing which shows embodiment. 2 and 3 are perspective views of the stent body.

  As illustrated in FIG. 1, the stent 1 according to this embodiment includes an outer polymer film 2 and an inner polymer film 3 on both inner and outer peripheral surfaces of a stent body 10 made of a tubular mesh capable of expanding diameter. It is.

  The stent body constituting the stent of the present invention has a length of about 2 to 40 mm, a diameter of 10 to 100%, particularly about 10 to 50%, and a thickness (thickness of the tubular portion) of 5. It has a tubular shape of ˜500 μm, more preferably 10 to 100 μm. The stent body is preferably in a mesh shape so that the diameter of the stent can be expanded flexibly, and in particular, is an oblique lattice shape as shown in FIG. 2 and the extending direction of the lattice is a spiral direction.

  The stent body is preferably made of a biocompatible metal. Examples of the biocompatible metal include stainless steel, titanium, tantalum, aluminum, tungsten, nickel / titanium alloy, cobalt / chromium / nickel iron alloy, and the like. Further, the stent body made of nickel / titanium alloy, cobalt / chromium / nickel iron alloy or the like is preferably subjected to heat treatment in order to memorize the shape. For example, when Nitinol, which is a nickel / titanium alloy, is used for the stent body, this heat treatment stores the shape by converting the crystal structure from the martensite phase to the austenite phase in the expanded shape, Self-expandability can be imparted to the body. In addition to metals, resins having excellent mechanical strength such as polyetheretherketone, aromatic polyamide, and polyimide can be used for the stent substrate.

  In addition, as described above, the stent body of the present invention can move the stent body between the outer polymer film and the inner polymer film. Therefore, the stent body is excellent in deformation followability. The overall shape does not need to be a straight tube, and may be a bent tube shape bent into a substantially L shape or a substantially square shape. That is, the surgeon can select an overall shape appropriate for the shape of the vessel to be placed.

  In FIG. 1, only one stent body 10 is covered with polymer films 2 and 3 to form a stent 1, but there are a plurality of stent bodies, for example, 2 to 10, preferably 2 to 5, and their longitudinal lengths. Between the stent main bodies, preferably forming an interval of about 0.1 to 1000% of the diameter of the stent main body, more preferably about 1 to 500%, and the outer polymer film and the inner polymer film. It may be integrated.

  In the stent 1 of FIGS. 1A and 1B, the outer polymer film 2 and the inner polymer film 3 with respect to the stent strut 1 </ b> A (lattice portion of the stent body 10) constituting the mesh of the stent body 10. Is not bonded, and the outer polymer film 2 and the inner polymer film 3 are bonded to each other in the stent slot 1B, that is, the mesh portion of the stent body 10. In FIG. 1A, a small circle indicated by a broken line in the stent slot 1 </ b> B portion indicates the bonding portion 4. In addition, the inner side polymer film 3 and the outer side polymer film 2 are adhere | attached in the band ring in the part in which the stent main body 10 of the both ends of the stent 1 does not exist.

  The bonding portion 4 formed in the stent slot 1B is preferably a dot-shaped bonding portion having a diameter of about 5 to 500 μm, particularly about 50 to 300 μm.

  As a constituent material of the flexible polymer film of the outer polymer film 2 and the inner polymer film 3, a highly flexible polymer elastomer is suitable, for example, polystyrene, polyolefin, polyester, polyamide, silicone, urethane. Further, various elastomers such as fluorine resin and natural rubber and copolymers thereof or polymer alloys thereof can be used. Among them, segmented polyurethane is most suitable because it is highly flexible and strong.

  A segmented polyurethane polymer has a flexible polyether portion as a soft segment and a portion rich in aromatic rings and urethane bonds as a hard segment, and the soft segment and the hard segment are phase-separated to form a fine structure. It is what. This segmented polyurethane polymer film is excellent in antithrombotic properties. Moreover, it is excellent in properties such as strength and elongation, and can be sufficiently expanded without breaking even when the stent is expanded in diameter.

  The polymer film such as the segmented polyurethane polymer film preferably has a thickness of 10 to 100 μm, particularly 20 to 50 μm.

  The polymer film is preferably provided with a plurality of fine holes. The fine holes may be randomly arranged, but preferably the fine holes are perforated at substantially uniform intervals. The fact that the micropores are perforated at a substantially uniform interval does not mean that the intervals are the same, but that the micropores are arranged at a substantially constant interval by a controlled method. Accordingly, the substantially uniform interval includes diagonal, circular, and elliptical arrangements that appear to be randomly arranged at first glance. The micropore may have any size or shape as long as the endothelial cells can enter and exit. Preferably, it is a circle having a diameter of 5 to 500 μm, most preferably 20 to 100 μm. Needless to say, other shapes such as an ellipse, a square, and a rectangle are also included. These are the states before expansion, and when the stent body is expanded and placed in the lumen, the circle may be deformed into an ellipse and the diameter may change accordingly.

  If the arrangement density of the micropores is too high, the strength of the polymer film is lowered and the intimal tissue penetrates too much. If the density is too low, the endothelial cells do not sufficiently grow inside the stent. Therefore, the micropores are arranged on a plurality of straight lines at intervals of 50 to 500 μm, preferably 100 to 300 μm. The plurality of straight lines include, for example, 10 to 50 straight lines arranged at a predetermined constant angular interval in the axial direction of the stent.

  The stent 1 in which the outer polymer film 2 and the inner polymer film 3 are not bonded to the stent main body 10, and the outer polymer film 2 and the inner polymer film 3 are bonded in a dot shape at the stent slot 1B and in a band shape at both ends. Can be produced by applying a method such as that described in Japanese Patent Application No. 2003-169510 by the present applicant.

  That is, the stent body is sandwiched between two tubular polymer films, and the outer polymer film 2 and the inner polymer film 3 are heat-sealed only at both end portions in the mold. A laser beam that is pre-filled with a photo-curing resin in the part to be bonded between the outer polymer film and the inner polymer film, and the diameter of the light is reduced to the same size as the diameter of the dotted adhesive part. Etc. to cure and bond the photo-curable resin. Alternatively, using a heating roller with a plurality of pins projecting on the outer peripheral surface, a stent body covered with an inner and outer polymer film is attached to a mandrill (mantrel), and the mandrill is heated and pressurized with the heating roller to inner and outer polymer film It is also possible to adopt a method in which the dots are heat-sealed in a stent slot portion.

  The fine pores of the polymer film can be provided by perforating with a laser or the like after the outer polymer film and the inner polymer film are coated on the stent body by the above production method.

  In the present invention, the adhesive portion need not be provided in all stent slots of the stent body, and may be provided only in a part of the stent slot 1B. For example, every two or two stent slots may be provided so as not to form an adhesive portion between adjacent stent slots. Further, as described above, laser perforation may be further performed on the formed bonded portion, and by providing such perforation, the engraftment of vascular endothelial cells is promoted as described above. As a method of providing such a perforation, for example, it is possible to form a perforation having a diameter of about 30 μm at the substantially central portion of a spot-like adhesion portion having a diameter of 50 μm, or a spot-like adhesion portion having a diameter of 50 μm. When providing, by using a two-wavelength mixed laser of a YAG laser with a wavelength of 1064 nm focused to 50 μm and a 266 nm quadruple wave YAG laser focused to 30 μm, adhesion and perforation can be performed simultaneously.

  FIG. 1 (c) shows a structure in which the bonding portion 4 is provided in a part of the stent slot 1 </ b> B and the micropore 5 is formed in the bonding portion 4.

  In such a stent, the non-bonded portion between the outer polymer film 2 and the inner polymer film 3 in the stent slot 1B portion of the stent body 10 may be a simple gap or may be filled with a drug or other filler. good. In the case of a simple gap, the polymer film 2 and 3 can be prevented from sticking to each other because the portion is swollen with air.

  In the case of filling a drug or the like, the filler may be, for example, heparin, low molecular weight heparin, hirudin, argatroban, formacholine, bapiprost, prostamorin, prostaquilin homologue, dextran, lofepro-algchloromethylketone, dipyridamole , Glycoprotein platelet membrane receptor antibody, recombinant hirudin, thrombin inhibitor, vascular peptin, vascular tensin converting enzyme inhibitor, steroid, fibroblast growth factor antagonist, fish oil, omega-3 fatty acid, histamine, antagonist , HMG-CoA reductase inhibitor, ceramine, serotonin blocking antibody, thioprotease inhibitor, trimazole pyridimine, interferon, vascular endothelial growth factor (VEGF), rapamycin, FK506, etc. Aqueous solution such as physiological saline containing glycerol, ethylene glycol, solution with a hydrophilic solvent such as an alcohol, atactic PP, EVA, low molecular weight PE, silicone oil, gelatin, collagen, hyaluronic acid, pullulan, and the like. These fillers can also impart sustained release properties that are gradually released from the micropores of the polymer film. It can also be filled with radioactive substances, magnetic powder, etc. In this case, in the treatment of cancerous vascular sites, suppression of cancer progression by radiation, thermotherapy of cancer by electromagnetic induction fever may be performed. it can. Furthermore, by filling the magnetic material, in the treatment after stent placement in a stenotic blood vessel, the vascular smooth muscle cells contract from the synthetic type by stimulating the affected part by vibrating the stent by electromagnetic induction by applying magnetic force from outside the body. It is possible to suppress excessive proliferation of smooth muscle cells by inducing transformation and / or induction of differentiation into a mold. Such heat generation, vibration, and weak current processing of the stent by electromagnetic induction can all be regarded as a minimally invasive prognosis management method.

  In such a filling, when a stent is manufactured by the above-described method, the stent body is sandwiched between two tubular polymer films, and the outer polymer film 2 and the inner polymer film 3 are heated only at one end portion. It can be filled between the outer polymer film and the inner polymer film by injecting the filler into a bag-like pocket portion formed by fusing.

  In the present invention, a base polymer film such as a segmented polyurethane polymer film constituting the outer polymer film and the inner polymer film may be coated with a biodegradable polymer. Examples of such biodegradable polymers include gelatin, polylactic acid, polyglycolic acid, caprolactone, lactic acid-glycolic acid copolymer, polygioxanone, and chitin.

  The biodegradable polymer may contain a therapeutic agent such as an antiplatelet agent, an antithrombotic agent, a growth promoter, a growth inhibitor, or an immunosuppressant. This therapeutic agent is released into the body as the biodegradable polymer degrades, and is effective in suppressing the formation of thrombus and promoting the proliferation of endothelial cells to coat the inner surface of the stent with endothelial cells at an early stage. It is.

  This treatment includes heparin, low molecular weight heparin, hirudin, argatroban, formacholine, bapiprost, prostamorin, prostakyrin congeners, dextran, lofepro-algchloromethylketone, dipyridamole, glycoprotein platelet membrane receptor antibody, combination Reversible hirudin, thrombin inhibitor, vascular peptin, vascular tensin converting enzyme inhibitor, steroid, fibroblast growth factor antagonist, fish oil, omega-3 fatty acid, histamine, antagonist, HMG-CoA reductase inhibitor, ceramine, Examples include serotonin blocking antibodies, thioprotein inhibitors, trimazole pyridimine, interferon, vascular endothelial growth factor (VEGF), rapamycin, FK506, and the like.

  The biodegradable polymer coating layer can be formed by immersing the stent in a biodegradable polymer solution. Polymerization may be promoted by ultraviolet rays after being dipped in the polymer solution and pulled up. When the therapeutic agent is added to the biodegradable polymer solution, a coating containing the therapeutic agent is formed. By adjusting the biodegradable polymer type, molecular weight, coating thickness, and the like, it is possible to set the time and period during which the therapeutic agent is released into the body.

  The outer surface of the stent of the present invention may be coated with a lubricious polymer in order to smoothly move in fine blood vessels in the human body. Examples of such a lubricious polymer include polyethylene glycol, polyacrylamide, and polyvinyl pyrrolidone.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

Example 1
As the stent body, a mesh-shaped stent body 10 having a diameter of 4 mm, a length of 7 mm, and a thickness of 0.1 mm shown in FIG. 2 was employed. FIG. 3 is a side view of the metallic stent body 10 ′ after expansion. The metal stent body 10 ′ has a diameter of 8 mm, a length of 7 mm, and a thickness of 0.1 mm.

  A stent was manufactured by coating the inner and outer peripheral surfaces of the metal stent body 10 with segmented polyurethane polymer films each having a thickness of 30 μm.

  Specifically, a tube made of a thermoplastic polyurethane resin having an outer diameter of 3.8 mm (Milactolan E980 manufactured by Nihon Milactolan) has an outer diameter of 3.5 mm, 1 mm long SUS440 portions at both ends, and 7 mm between them. It was fitted into a mantle having a long PTFE portion and stored in a refrigerator at 4 ° C. The mantrel fitted with the resin tube was passed through the inside of one stent body 10.

  Next, a tube made of a thermoplastic polyurethane resin having an outer diameter of 4.3 mm (Milactolan E980 manufactured by Nippon Milactolan) was fitted into a PTFE mantle having an outer diameter of 4.1 mm, and this end portion was laminated with the stent body and the resin tube. Then, the ends and the centers of the inserted mantles were connected in alignment, and a tube with an outer diameter of 4.3 mm was slid from the mantle while applying ultrasonic waves in methanol and placed on the stent body.

  In this manner, a resin tube having an outer diameter of 4.3 mm, a stent body, a resin tube having an outer diameter of 3.8 mm, and a mantle having an outer diameter of 3.5 mm are laminated from the outside. The outer polymer film and the inner polymer film were heat-sealed only at both ends in the mold.

  Next, using a heating roller with a plurality of pins protruding on the outer peripheral surface, the inner and outer polymer films are made dotted by heating and pressurizing the mantle that has the stent body covered with the inner and outer polymer films. Heat fusion was performed at the stent slot. The diameter of this heat fusion part was about 50 micrometers, and the heat fusion part was formed in all the stent slots of the stent main body.

Comparative Example 1
In Example 1, as the stent body, the mesh-shaped stent body 10 having a diameter of 4 mm, a length of 25 mm, and a thickness of 0.1 mm shown in FIG. 2 was employed. A PTFE mold having an inner diameter of 4.1 mm is rotated at 6000 rpm around the center, and a 10% THF solution of polyurethane resin is supplied into the mold while the injection position is moved in the axial direction of the mold. An outer layer polymer film having a thickness of 30 μm was formed by heating. The stent body is placed in this, and the outer polymer film and the inner polymer film are bonded together to the stent body by supplying a THF solution of polyurethane resin to form a film while rotating the mold in the same manner. A stent was produced in the same manner as in Example 1 except for the above. The thickness of the inner layer polymer film was 30 μm.

  When the stents produced in Example 1 and Comparative Example 1 were expanded, the stent of Example 1 expanded in diameter by sliding the stent body between the polymer films, so that the polymer film was not twisted or wrinkled. Although the stent of Comparative Example 1 was able to be expanded without difficulty, the polymer film and the stent body were completely in close contact with each other, so that the polymer film was twisted or wrinkled, and the stent was expanded or greatly deformed or bent. It was confirmed that it could not stand.

FIG. 1A is a perspective view showing an embodiment of the stent of the present invention, FIG. 1B is an enlarged view of a cross section taken along line BB in FIG. 1A, and FIG. It is sectional drawing which shows embodiment. It is a perspective view of a stent main body. It is a perspective view of the stent main body expanded in diameter. It is a perspective view of the stent of Unexamined-Japanese-Patent No. 11-299901. FIG. 4 is a perspective view of the stent of FIG. 3 having an enlarged diameter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stent 1A Stent strut 1B Stent slot 2 Outer polymer film 3 Inner polymer film 4 Adhesion part 5 Micropore 10 Stent body

Claims (12)

A stent comprising a stent main body made of a tubular mesh capable of expanding diameter, a cylindrical outer polymer film overlapping the outer peripheral surface of the stent main body, and a cylindrical inner polymer film overlapping the inner peripheral surface of the stent main body Because
The stent, wherein the outer polymer film and the inner polymer film are non-adhered to the stent body, and are adhered to each other in at least a part of the mesh portion of the mesh stent body.   2. The stent according to claim 1, wherein the outer polymer film and the inner polymer film are bonded in a dot shape.   2. The stent according to claim 1, wherein the outer polymer film and the inner polymer film are bonded to each other in a dot shape, and then a perforation is provided in the bonded portion.   The stent according to any one of claims 1 to 3, wherein the outer polymer film and the inner polymer film are flexible polymer films having a plurality of micropores.   The physiologically active substance or radioactive substance according to any one of claims 1 to 4, wherein a portion where the outer polymer film and the inner polymer film are not bonded is provided between the outer polymer film and the inner polymer film. And a stent filled with one or more selected from the group consisting of magnetic materials.   The stent according to any one of claims 1 to 5, wherein the outer polymer film and / or the inner polymer film is covered with a biodegradable polymer.   The stent according to claim 6, wherein the biodegradable polymer contains a drug.   8. The platelet membrane receptor of claim 7, wherein the drug is heparin, low molecular weight heparin, hirudin, argatroban, formacholine, bapiprost, prostamorin, prostaquilin homologue, dextran, lofepro-alguchloromethyl ketone, dipyridamole, glycoprotein. Antibody, recombinant hirudin, thrombin inhibitor, vascular peptin, vascular tensin converting enzyme inhibitor, steroid, fibroblast growth factor antagonist, fish oil, omega-3-fatty acid, histamine, antagonist, HMG-CoA reductase inhibitor , Seramine, serotonin blocking antibody, thioprotein inhibitor, trimazole pyridimine, interferon, vascular endothelial growth factor (VEGF), rapamycin, and FK506 Stent, characterized in that it.   The stent according to any one of claims 4 to 8, wherein the micropores are arranged at substantially uniform intervals.   10. The stent according to claim 9, wherein the micropores are provided at intervals of 50 to 500 [mu] m and have a diameter of 5 to 500 [mu] m.   11. The polymer film according to claim 1, wherein the polymer film is a polystyrene-based, polyolefin-based, polyester-based, polyamide-based, silicone-based, urethane-based, fluororesin-based, natural rubber-based elastomer, or a copolymer thereof. And a stent selected from the group consisting of these polymer alloys.   The stent according to any one of claims 1 to 11, wherein the polymer film has a thickness of 10 to 100 µm.

Images