Coated stent for coronary artery and method of manufacturing same

Abstract

The purpose of the present disclosure is to provide a coated stent for coronary arteries, which enables effective treatment of coronary artery perforations that may occur during procedures such as those for angina pectoris and myocardial infarction. The coated stent for coronary arteries according to the present disclosure can prevent restenosis after implantation and provides enhanced in vivo stability due to reduced detachment force.

Description

Covered stent for coronary artery and method for manufacturing the same

[0001] The present invention relates to a membrane-type stent for coronary artery and a method for manufacturing the same.

[0002] Coronary arteries are blood vessels that supply oxygen and nutrients to the heart, surrounding it in a crown-like shape. The various diseases that occur as arteriosclerosis progresses in the coronary arteries are called "coronary artery disease." Atherosclerosis refers to a condition in which cholesterol accumulates in the arteries for various reasons, leading to inflammation and other factors that harden and narrow the arteries. When a coronary artery narrows and causes chest pain during exercise, it is called angina. When a coronary artery suddenly becomes completely blocked, resulting in the death of the heart muscle, it is called myocardial infarction.

[0003] To treat coronary artery disease, interventional procedures are performed to expand the diameter of the narrowed blood vessel by inserting a stent into the narrowed area of ​​the blood vessel. This stent expands the diameter of the blood vessel to facilitate blood flow. This interventional procedure involves inserting a balloon-embedded stent into the blood vessel using a catheter, injecting air into the balloon to expand the stent's diameter, physically expanding the blood vessel's diameter.

[0004] The initially developed stents were made of metal and had a simple structure in which the outer diameter was expanded by a balloon. After the procedure, the stent implanted inside the blood vessel caused a foam cell phenomenon in which white blood cells such as neutrophils were deposited due to a foreign body reaction, and there was a problem in that restenosis occurred due to the action of platelets caused by wounds and inflammatory reactions occurring in the blood vessel during the implantation.

[0005] To address the problems of conventional metal stents, drug-eluting stents coated with anticoagulants to prevent thrombosis on the surface, biodegradable stents that naturally degrade over time, and self-expanding metal stents have been developed. Among these, stent coating technologies are actively being utilized, such as coating stents with anti-restenosis agents to prevent restenosis or applying a polymer coating to the surface to prevent thrombosis within the stent mesh.

[0006] Covered stents, which are metal stents coated with a fabric-like membrane, are used in surgeries and procedures for aortic aneurysms at risk of rupture, as well as in various clinical applications, including peripheral arterial perforation. Furthermore, in the coronary artery, covered stents are used to treat various lesions, including coronary artery perforation, coronary arteriovenous fistulas, and coronary aneurysms.

[0007] However, there is a problem that the film formed on the surface during stent coating may come off or the stent itself may come out of place when placed on the lesion, and thus, there is a need for the development of a technology that can resolve the limitations of such film-type stents.

[0008] The present disclosure aims to provide a coronary artery membrane-type stent that can effectively treat coronary artery perforation that may occur during procedures such as angina pectoris and myocardial infarction.

[0009] In addition, the present disclosure aims to provide a method for manufacturing a coronary artery membrane-type stent that can prevent restenosis after implantation and has high in vivo stability due to reduced dislodgment force.

[0010] The method for manufacturing a coronary artery membrane-type stent of the present disclosure may include the steps of: expanding a stent substrate; first coating the expanded stent substrate by electrospinning a polymer solution; compressing the stent substrate after forming a coating layer; and second coating the compressed stent substrate by electrospinning a polymer solution.

[0011] In a method for manufacturing a coronary artery membrane-type stent according to one embodiment of the present disclosure, the nanofibers formed as a first coating may bond between the nanofibers formed as a second coating and the stent.

[0012] In a method for manufacturing a membrane-type stent for coronary artery according to one embodiment of the present disclosure, the polymer solution used in the first coating and the second coating may each be a polyvinyl alcohol solution.

[0013] In a method for manufacturing a coronary artery membrane-type stent according to one embodiment of the present disclosure, the expanding step may be such that the diameter of the stent substrate expands by 1.2 to 3 times.

[0014] In a method for manufacturing a membrane-type stent for coronary artery according to one embodiment of the present disclosure, the compressing step may be to compress the diameter of the stent substrate by 0.1 to 0.8 times.

[0015] In a method for manufacturing a coronary artery membrane-type stent according to one embodiment of the present disclosure, the compressing step may be such that the nanofibers formed as the primary coating are inserted into and fixed to the stent frame.

[0016] In a method for manufacturing a coronary artery membrane-type stent according to one embodiment of the present disclosure, the polyvinyl alcohol solution may contain 5 to 30 parts by weight of a cross-linking agent per 100 parts by weight of polyvinyl alcohol.

[0017] In a method for manufacturing a coronary artery membrane-type stent according to one embodiment of the present disclosure, the polyvinyl alcohol solution may contain 5 to 20 wt% of polyvinyl alcohol relative to the total amount.

[0018] A method for manufacturing a coronary artery membrane-type stent according to one embodiment of the present disclosure may further include a step of crosslinking the second-coated stent at 100 to 200°C.

[0019] In a method for manufacturing a coronary artery membrane-type stent according to one embodiment of the present disclosure, electrospinning in the first coating and the second coating may be by spraying a polyvinyl alcohol solution at a flow rate of 0.1 to 1 ml / h for 10 seconds to 5 minutes.

[0020] In a method for manufacturing a coronary artery membrane-type stent according to one embodiment of the present disclosure, the diameter of the metal rod inside the stent in the electrospinning of the first coating and the second coating may be 0.3 to 2 mm.

[0021] The coronary artery membrane-type stent of the present disclosure may include a polyvinyl alcohol nanofiber coating layer cross-linked with citric acid on the surface of the stent substrate.

[0022] In a coronary artery membrane-type stent according to one embodiment of the present disclosure, the coating layer may be manufactured by first coating and second coating of polyvinyl alcohol nanofibers through electrospinning.

[0023] In a coronary artery membrane-type stent according to one embodiment of the present disclosure, the coating layer may be formed by cross-linking polyvinyl alcohol nanofibers with citric acid after the first coating and the second coating.

[0024] In a coronary artery membrane-type stent according to one embodiment of the present disclosure, the thickness of the coating layer may be 100 to 200 μm.

[0025] In a coronary artery membrane-type stent according to one embodiment of the present disclosure, the diameter of the polyvinyl alcohol nanofibers may be 1 to 10 μm.

[0026] In a coronary artery stent according to one embodiment of the present disclosure, the diameter of the coronary artery stent may be 0.5 to 5 mm.

[0027] A coronary artery stent according to one embodiment of the present disclosure can prevent restenosis by the film on the surface of the stent after implantation, and can prevent detachment and stent thrombosis from occurring at the implantation site due to its excellent physical properties, thereby achieving stability in the body.

[0028] A method for manufacturing a coronary artery membrane-type stent according to one embodiment of the present disclosure has excellent bonding strength between the stent and the membrane, so that it is not easily peeled off, and can reduce the detachment force of the stent itself.

[0029] Figure 1 schematically illustrates a method for manufacturing a membrane-type stent for coronary arteries.

[0030] Figure 2 shows the appearance of a membrane-type stent for coronary artery measured using a confocal microscope.

[0031] Figure 3 shows the appearance of a coronary artery membrane-type stent inflated with a balloon after catheter placement.

[0032] Figure 4 shows changes in blood flow after stent implantation in angiography.

[0033] The present invention will be described in detail below. Terms used herein, unless specifically defined, should be interpreted as generally understood by those skilled in the art. The drawings and examples in this specification are intended to facilitate the understanding and practice of the present invention by those skilled in the art. Content that may obscure the gist of the invention may be omitted from the drawings and examples, and the present invention is not limited to the drawings and examples.

[0034] The singular forms used in this specification are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0035] Additionally, the numerical range used in the present invention includes lower and upper limits and all values ​​within that range, increments logically derived from the shape and width of the defined range, all doubly defined values, and all possible combinations of upper and lower limits of numerical ranges defined in different shapes. Unless otherwise specifically defined in the specification of the present invention, values ​​outside the numerical range that may arise due to experimental error or rounding of values ​​are also included in the defined numerical range.

[0036] In this specification, terms such as include, have, and have mean that a feature or component described in the specification exists, and unless specifically limited, do not preclude the possibility that one or more other features or components may be added.

[0037] The present disclosure aims to provide a coronary artery membrane-type stent that can effectively treat coronary artery perforation that may occur during procedures such as angina pectoris and myocardial infarction.

[0038] The present disclosure is designed to solve the problem of restenosis of conventional membrane-type stents and the problem of stent dislodgement after implantation, and to manufacture a stent with high stability properties.

[0039] Specifically, the method for manufacturing a coronary artery membrane-type stent of the present disclosure may include a step of expanding a stent substrate; a step of first coating the expanded stent substrate by electrospinning a polymer solution; a step of compressing the stent substrate after forming a coating layer; and a step of second coating the compressed stent substrate by electrospinning a polymer solution.

[0040] The method for manufacturing the above-described coronary artery membrane-type stent comprises a step of first electrospinning the stent substrate by expanding it, then second electrospinning it by contracting it, thereby coating it with nanofibers, thereby achieving excellent bonding strength between the stent and the membrane. The stent thus manufactured can prevent restenosis and dislodgement after implantation of conventional membrane-type stents, thereby achieving superior in vivo stability.

[0041] According to one embodiment, the nanofibers formed by the first coating may bond between the nanofibers formed by the second coating and the stent.

[0042] According to one embodiment, the polymer solution may include one or a mixture of two or more polymer materials selected from among PVA (polyvinyl alcohol), PVP (polyvinyl pyrrolidone), PEO (polyethylene oxide), CMC (carboxyl methyl cellulose), starch, PAA (polyacrylic acid), and hyaluronic acid, and specifically may be a polyvinyl alcohol (PVA) solution.

[0043] In the method for manufacturing a coronary artery membrane-type stent of the present disclosure, the expanding step may be such that the diameter of the stent substrate expands by 1.2 to 3 times, specifically by 1.5 to 3 times, and more specifically by 2 to 3 times.

[0044] In the method for manufacturing a coronary artery membrane-type stent of the present disclosure, the compressing step may be to compress the diameter of the stent substrate by 0.1 to 0.8 times, specifically by 0.2 to 0.7 times, and more specifically by 0.3 to 0.7 times.

[0045] Additionally, according to one embodiment, the compressing step may be such that the nanofibers formed by the first coating are inserted and fixed to the stent frame. The nanofibers formed by the first coating can then adhere to the nanofibers formed by the second coating and the stent, thereby achieving excellent bonding strength between the nanofibers and the stent.

[0046] The term 'polymer solution' in the present disclosure refers to a spinning solution used in the electrospinning of the present disclosure. According to one embodiment, a solution including polyvinyl alcohol is referred to as a 'polyvinyl alcohol solution', and may include other components to be described later.

[0047] According to one embodiment, the polyvinyl alcohol solution for the first coating and the second coating may contain 5 to 30 parts by weight of a cross-linking agent based on 100 parts by weight of polyvinyl alcohol, specifically 8 to 25 parts by weight, and more specifically 10 to 25 parts by weight of the cross-linking agent. When the cross-linking agent in the solution is less than 5 parts by weight based on 100 parts by weight of polyvinyl alcohol, a cross-linking reaction may not occur, and when it is more than 30 parts by weight, irritation may occur.

[0048] Specifically, the crosslinking agent is not limited to any substance capable of crosslinking water-soluble polymers, such as glyoxal, glutaraldehyde, and maleic acid hydride, but more specifically, it may be citric acid. The degree of crosslinking of polyvinyl alcohol can be controlled through the content of citric acid contained in the polyvinyl alcohol solution, the crosslinking temperature, and the like.

[0049] In addition, the polyvinyl alcohol solution may include at least one selected from the group consisting of water (H2O), ethanol, dimethyl acetamide (DMAc), N,N-dimethylformamide (DMF), Nmethyl-2-pyrrolidinone (NMP), dimethyl sulfoxide (DMSO), tetra-hydrofuran (THF), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), propylene carbonate (PC), acetic acid, formic acid, chloroform, dichloromethane, DMP, and acetone as a solvent, and may specifically include water and DMF. More specifically, water and DMF may be included in a ratio of 7:3, 6:4, or 5:5 with respect to the entire solvent, but may be included in a ratio of 6:4.

[0050] According to one embodiment, the polyvinyl alcohol solution used in the first coating and the second coating may contain 5 to 20 wt% of polyvinyl alcohol based on the total weight, and specifically, 5 to 15 wt%. If the content of polyvinyl alcohol in the solution exceeds 20 wt% based on the total weight, electrospinning may not occur due to intermolecular interactions, etc., and if it is less than 5 wt%, electrospinning may not occur, or may appear in the form of beads, etc. and may not be spun into the nanofiber form desired by the present invention.

[0051] A method for manufacturing a coronary artery membrane-type stent according to one embodiment of the present disclosure may further include a step of crosslinking the second-coated stent at 100 to 200°C, and specifically, crosslinking may be performed by heat treatment at 100 to 150°C for 10 minutes to 2 hours.

[0052] Specifically, the crosslinking formed through the above heat treatment may be formed according to a mechanism in which the ester bond (RCOOR') in polyvinyl alcohol is hydrolyzed (RCOOA + R'OH) by citric acid (A-OH), but is not limited thereto.

[0053] According to one embodiment, in the first coating and the second coating, electrospinning may be performed by spraying a polyvinyl alcohol solution at a flow rate of 0.1 to 1 ml / h for 10 seconds to 5 minutes. Specifically, the electrospinning may be performed by directly spraying the spinning solution prepared above in the diameter direction onto the stent by spraying it under a high-voltage electric field. At this time, the stent has a metal rod collector positioned in the hollow portion of the cylinder so that nanofibers can be evenly formed on the surface of the stent. The voltage at which electrospinning is performed is 10 to 20 kV, and the vertical distance between the end of the spraying portion from which the spinning solution is sprayed and the stent may be 5 to 20 cm, specifically, 5 to 15 cm or 8 to 12 cm. The discharge rate of the spray solution may be specifically 0.1 to 0.8 ml / h, more specifically 0.2 to 0.6 ml / h. At this time, the first coating of the present disclosure may be spraying the polyvinyl alcohol solution for 10 seconds to 1 minute, specifically 20 seconds to 40 seconds, and the second coating may be spraying for 1 minute to 3 minutes.

[0054] According to one embodiment, the diameter of the metal rod inside the stent in the electrospinning of the first coating and the second coating may be 0.3 to 2 mm, and specifically 0.5 to 1.5 mm. In this case, the diameter of the stent when expanded and compressed and the thickness of the coating layer can be controlled depending on the diameter of the metal rod.

[0055] The coronary artery membrane-type stent of the present disclosure may include a polyvinyl alcohol nanofiber coating layer cross-linked with citric acid on the surface of the stent substrate.

[0056] According to one embodiment, the coating layer may be manufactured by first coating and second coating of polyvinyl alcohol nanofibers through electrospinning. Through the first coating and second coating, the nanofibers can be sandwiched and fixed between the stent frames, and specifically, the first-coated nanofibers can bond between the second-coated nanofibers and the stent substrate, thereby implementing excellent fixing strength.

[0057] Additionally, according to one embodiment, the coating layer may be cross-linked with polyvinyl alcohol nanofibers using citric acid after the first and second coatings. In this case, the cross-linking may be performed by heat-treating the stent at 100 to 200°C for 10 minutes to 2 hours.

[0058] According to one embodiment, the thickness of the coating layer may be 100 to 200 μm, specifically 100 to 180 μm or 100 to 150 μm, more specifically 110 to 130 μm.

[0059] According to one embodiment, the diameter of the polyvinyl alcohol nanofibers may be 1 to 10 μm, specifically 2 to 8 μm, and more specifically 3 to 5 μm.

[0060] According to one embodiment, the diameter of the coronary artery stent may be 0.5 to 5 mm, specifically 1 to 4 mm, and more specifically 1 to 2 mm.

[0061] The coronary artery covering stent of the present disclosure has excellent bonding strength between the polyvinyl alcohol nanofiber covering and the metal material of the stent, thereby preventing the nanofibers from being peeled off when passing through the catheter during the implantation process. In addition, the stent does not detach after implantation and prevents restenosis, thereby exhibiting excellent stability in the body. Accordingly, the coronary artery covering stent of the present disclosure can be effectively used to alleviate coronary artery diseases such as angina pectoris and myocardial infarction.

[0062] Hereinafter, the method for manufacturing a coronary artery stent according to the present invention will be described in more detail through specific examples. However, the following examples are merely references for further explanation of the present invention and are not intended to limit the present invention, which may be implemented in various forms. Furthermore, the terminology used in the description of the present invention is merely intended to effectively describe specific embodiments and is not intended to limit the present invention.

[0063]

[0064] [Example 1] Manufacturing of a membrane-type stent for coronary artery

[0065] Preparation of polyvinyl alcohol solution

[0066] A polyvinyl alcohol solution (radiation solution) was prepared by mixing the components shown in Table 1 below for the entire solution.

[0067] Composition (wt%) H2053.1Dimethylformamide (DMF)35.4Poly vinyl alcohol (PVA)10Citric acid (CA)2.0

[0068]

[0069] Stent coating

[0070] A balloon was connected to an inflator, and a cobalt-chromium alloy metal stent (BMS: bare metal stent) with an initial diameter of 1.5 mm was inserted and fixed to the balloon. The balloon was then inflated to a stent diameter of 3.5 mm, and the stent was attached to a metal rod (collector) with a diameter of 0.65 mm.

[0071] The above polyvinyl alcohol composition was first coated by electrospinning onto a stent for 1 minute under the conditions of an applied voltage of 13 kV, a radiation distance of 10 cm, and a flow rate of 0.4 ml / h.

[0072] After the first coating, the polyvinyl alcohol composition was electrospun onto the stent for a second coating under the same conditions as described above for 2 minutes while the stent was compressed again to a diameter of 1.2 mm. Thereafter, the stent was dried at 120°C for 1 hour to crosslink the polyvinyl alcohol fibers included in the coating layer.

[0073]

[0074] [Example 2]

[0075] A stent was manufactured using the same method as in Example 1, except that a metal rod with a diameter of 1.2 mm was used in the manufacturing process of Example 1.

[0076]

[0077] [Example 3]

[0078] A double-film stent was manufactured in the same manner as in Example 1, except that the coating composition in the manufacturing process of Example 1 was as shown in Table 2 below.

[0079] Composition (wt%) H2052.8Dimethylformamide (DMF)35.2Poly vinyl alcohol (PVA)10Citric acid (CA)1.5

[0080]

[0081] [Comparative Example 1] Single-film stent

[0082] The same coating composition as in Example 1 was electrospun onto a cobalt-chromium alloy metal stent (BMS: bare metal stent) with an initial diameter of 1.5 mm under the same conditions as the first coating in Example 1 to form a coating layer. In addition, the coating layer was dried at 120°C for 1 hour to crosslink.

[0083] In the case of Comparative Example 1, the stent with an initial diameter of 1.5 mm did not change in diameter after coating, indicating that the first coating layer on the surface of the stent was peeled off during the catheter implantation process.

[0084]

[0085] Investigation of the diameter of the stent

[0086] The diameter of the stent including the coating layer was measured over time during the manufacturing process of Examples 1 and 2, and is shown in Table 3 below.

[0087] At this time, the diameter of the stent measured after the stent was inserted into the balloon and compressed after the secondary coating of Examples 1 and 2 and the diameter of the stent measured after the stent was expanded in the blood by connecting the balloon to the balloon inflator are shown in Table 3 below.

[0088] Manufacturing ProcessExample 1Example 2Initial stent1.5 mm1.6 mmExpanded stent3.5 mm3.4 mmAfter first coating3.5 mm3.4 mmCompressed stent1.2 mm1.6 mmAfter second coating1.2 mm1.7 mmBalloon compressed stent1.2 mm1.7 mmBalloon expanded stent3.4 mm3.6 mm

[0089] According to Table 3 above, it can be seen that the diameter of the stent and the thickness of the coating layer when expanded and compressed can also be controlled differently depending on the diameter of the metal rod collector located inside the stent cylindrical hollow structure during the electrospinning process.

[0090]

[0091] Investigation of the physical properties of stents

[0092] The polyvinyl alcohol nanofiber material of the stent of Example 1 was stained with DAPI (4',6-diamidino-2-phenylindole) and the results observed using a confocal microscope are shown in Fig. 2.

[0093] As shown in Fig. 2, it can be confirmed that the nanofibers cover the surface of the stent frame and are densely interwoven between the stent frames. This can prevent the nanofibers in the coating layer from being peeled off when a catheter passes through the stent tube, and can also prevent them from being easily detached after implantation in the coronary artery area.

[0094] The diameter of the fiber containing PBS measured through the image values ​​of the above confocal microscope is approximately 4 μm, and the thickness of the coating layer formed on the surface is 120 μm.

[0095]

[0096] [Experimental Example 1] Stent Expansion Test

[0097] The appearance of the stents of Examples 1 to 3 after being expanded through the balloon of the catheter is shown in Fig. 3, and the expansion rate of each stent is shown in Table 4 below.

[0098] Example 1 Example 2 Example 3 Stent expansion rate 277% 206% 277%

[0099] According to Table 4, in the cases of Examples 1 and 3, when the catheter balloon was inflated, the expansion rate of the stent was approximately 71% higher than that of Example 2.

[0100] In addition, as shown in FIG. 3, Example 1 shows that the nanofibers have poor flexibility, causing them to tear and become damaged. To compensate for this, Example 3, which contains a lower content of citric acid as a crosslinking agent, shows that no holes are formed and the flexibility of the nanofibers increases somewhat, as shown in FIG. 3.

[0101]

[0102] [Experimental Example 2] Stent implantation test in vivo

[0103] As shown in Fig. 4, a sample of a membrane-type stent system was prepared by attaching the stent of Example 3 to a balloon catheter. The porcine carotid artery was then cut down, and a guide wire was placed into the desired blood vessel using a sheath and catheter. To deliver the membrane-type stent, angiography was performed. A 20 mm membrane-type stent was implanted at the point where the diagonal branch of the left anterior descending (LAD) branch bifurcates, to determine whether the stent could block blood flow in the D1 branch.

[0104] First, the balloon was expanded to match the size of the blood vessel, and then further over-expanded using an NC balloon. Finally, final angiography revealed that blood flow in the D1 branch was occluded, confirming that the membrane-type stent of the present disclosure can be useful in the treatment of vascular perforation, rupture, and aneurysms.

[0105]

[0106] As described above, the present invention has been described through specific matters and limited examples and comparative examples, but these are provided only to help a more general understanding of the present invention, and the present invention is not limited to the above examples, and those skilled in the art to which the present invention pertains can make various modifications and variations based on this description.

[0107] Therefore, the idea of ​​the present invention should not be limited to the described embodiments, and all things that are equivalent or equivalent to the following claims as well as the claims are considered to fall within the scope of the idea of ​​the present invention.

Claims

1. Step of expanding the stent substrate; A step of first coating the expanded stent substrate by electrospinning a polymer solution; A step of compressing the stent substrate after forming a coating layer; and A method for manufacturing a membrane-type stent for coronary artery, comprising the step of performing a second coating by electrospinning a polymer solution onto the compressed stent substrate.

2. In paragraph 1, A method for manufacturing a coronary artery membrane-type stent, wherein the nanofibers formed by the first coating adhere between the nanofibers formed by the second coating and the stent.

3. In paragraph 1, A method for manufacturing a coronary artery membrane-type stent, wherein the polymer solutions used in the first and second coatings are each polyvinyl alcohol solutions.

4. In paragraph 1, A method for manufacturing a coronary artery membrane-type stent, wherein the expanding step expands the diameter of the stent substrate by 1.2 to 3 times.

5. In paragraph 1, A method for manufacturing a coronary artery membrane-type stent, wherein the compressing step compresses the diameter of the stent substrate to 0.1 to 0.8 times.

6. In paragraph 1, A method for manufacturing a coronary artery membrane-type stent, wherein the above-mentioned compressing step is such that the nanofibers formed by the above-mentioned first coating are fixed by being inserted into a stent frame.

7. In paragraph 3, A method for manufacturing a coronary artery membrane-type stent, wherein the polyvinyl alcohol solution contains 5 to 30 parts by weight of a cross-linking agent per 100 parts by weight of polyvinyl alcohol.

8. In paragraph 3, A method for manufacturing a coronary artery membrane-type stent, wherein the polyvinyl alcohol solution contains 5 to 20 wt% of polyvinyl alcohol based on the total weight of the solution.

9. In paragraph 1, A method for manufacturing a coronary artery membrane-type stent, further comprising a step of cross-linking the second coated stent at 100 to 200°C.

10. In paragraph 3, A method for manufacturing a coronary artery membrane-type stent, wherein in the first coating and the second coating, electrospinning is performed by spraying a polyvinyl alcohol solution at a flow rate of 0.1 to 1 ml / h for 10 seconds to 5 minutes.

11. In paragraph 1, A method for manufacturing a membrane-type stent for a coronary artery, wherein the diameter of the metal rod inside the stent in the electrospinning of the first coating and the second coating is 0.3 to 2 mm.

12. A coronary artery membrane-type stent comprising a polyvinyl alcohol nanofiber coating layer cross-linked with citric acid on the surface of the stent substrate.

13. In paragraph 12, A coronary artery membrane-type stent, wherein the coating layer is manufactured by first coating and second coating of polyvinyl alcohol nanofibers through electrospinning.

14. In paragraph 13, A coronary artery membrane-type stent, wherein the coating layer is formed by cross-linking polyvinyl alcohol nanofibers with citric acid after the first and second coatings.

15. In paragraph 12, A membrane-type stent for a coronary artery, wherein the thickness of the coating layer is 100 to 200 μm.

16. In paragraph 12, A coronary artery membrane-type stent, wherein the diameter of the polyvinyl alcohol nanofibers is 1 to 10 μm.

17. In paragraph 12, A coronary artery stent having a diameter of 0.5 to 5 mm.

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