Covered stent and preparation method thereof

Abstract

The invention discloses a covered stent and a preparation method thereof, and relates to the technical field of medical instruments, the covered stent comprises a stent body, and the radial supporting strength of the middle section of the stent body is greater than that of the two end sections of the stent body. The preparation method of the covered stent comprises the following steps: obtaining the stent body, and enabling the radial supporting strength of the middle section of the stent body to be greater than that of the two end sections of the stent body. According to the covered stent and the preparation method thereof, high radial supporting force can be provided for a narrow part, the situation that the supporting force of a normal blood vessel section is too large, so that the blood vessel wall is stimulated or the normal blood vessel wall is difficult to attach can be prevented, then the normal blood vessel section is prevented from being damaged, the treatment effect can be improved, and complications are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and particularly to a covered stent and a preparation method thereof. Background Art

[0002] A covered stent is a medical device used to treat diseases such as vascular or lumen stenosis, aneurysm, etc. Vascular stenosis is a common cardiovascular disease, and balloon-expandable covered stents are an important means for treating this disease. Existing balloon-expandable covered stents are usually processed by a single material treatment method as a whole, and all stent units on the entire balloon-expandable covered stent adopt the same structure, resulting in the same radial support at each position of the entire balloon-expandable covered stent, and there are the following problems: First, the radial support force distribution of the balloon-expandable covered stent is unreasonable: during application, high support force is required at the stenosis site to maintain vascular patency, but excessive support force in the normal vascular segment may stimulate the vascular wall, leading to intimal injury, dissection, or thrombosis formation. The traditional stent has a uniform overall radial support force and is difficult to meet the requirements of effectively supporting the stenosis site and not causing damage to the normal vascular segment at the same time. Second, the wall attachment is insufficient: if the support force at both ends of the stent is too high, it is difficult to fit the natural curvature of the normal blood vessel, increasing the risk of vascular injury. Summary of the Invention

[0003] The purpose of the present invention is to provide a covered stent and a preparation method thereof to solve the problems existing in the above-mentioned prior art, which can not only provide high radial support force for the stenosis site, but also prevent the support force in the normal vascular segment from being too large to stimulate the vascular wall or being difficult to fit the normal vascular wall, thereby preventing damage to the normal vascular segment. The present invention can improve the treatment effect and reduce complications.

[0004] To achieve the above purpose, the present invention provides the following solutions: The present invention provides a covered stent, including a stent body, and the radial support strength of the middle section of the stent body is greater than that of the two end sections of the stent body.

[0005] Preferably, the middle section of the stent body is a non-annealed stent, and both end sections of the stent body are annealed stents; the wall thickness of the stent in the middle section of the stent body is greater than the wall thickness of the stent in the two end sections of the stent body.

[0006] Preferably, the middle section of the stent body includes at least two sequentially connected closed-loop stents, and both end sections of the stent body include at least two sequentially arranged open-loop stents; the two end sections of the stent body are non-annealed stents, and the middle section of the stent body is an annealed stent.

[0007] Preferably, at least one connecting rod is arranged between two adjacent closed-loop stents.

[0008] Preferably, there is an included angle between the connecting rod and the axis of the bracket body.

[0009] Preferably, each of the open annular brackets includes a plurality of bracket units, and each of the bracket units is a U-shaped unit or a V-shaped unit. The plurality of bracket units are sequentially connected end to end to form an annular bracket.

[0010] Preferably, the material of the middle section of the bracket body is cobalt-chromium alloy, and the materials of both end sections of the bracket body are cobalt-chromium alloy.

[0011] The present invention also provides a method for manufacturing a covered stent, including the following steps: obtaining a bracket body, and making the radial support strength of the middle section of the bracket body greater than the radial support strength of both end sections of the bracket body.

[0012] Preferably, it further includes: respectively obtaining the middle section of the bracket body and both end sections of the bracket body, and annealing both end sections of the bracket body.

[0013] Preferably, the methods for obtaining the middle section of the bracket body and both end sections of the bracket body include: performing laser cutting or etching on a metal tube to process at least two open annular brackets at both end sections of the metal tube and at least two closed annular brackets at the middle section of the metal tube.

[0014] The present invention has achieved the following technical effects compared with the prior art: The present invention provides a covered stent and a method for manufacturing the same, including a bracket body. The radial support strength of the middle section of the bracket body is greater than the radial support strength of both end sections of the bracket body, so that the middle section of the bracket can provide a high radial support force, and both end sections can provide a low radial support force. The middle section is used to support the narrow part, and both end sections are used to support the normal blood vessel section. The present invention optimizes the radial support strength of the bracket body, which can not only provide a high radial support force for the narrow part, but also prevent the support force of the normal blood vessel section from being too large to stimulate the blood vessel wall or be difficult to fit the normal blood vessel wall, thereby preventing damage to the normal blood vessel section. The present invention can improve the treatment effect and reduce complications. Description of the Drawings

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the following described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0016] Figure 1Three-dimensional structure schematic diagram of the first form of the first covered stent provided for Example 1; Figure 2 Three-dimensional structure schematic diagram of the first form of the first covered stent provided for Example 1; Figure 3 Front view schematic diagram of the first form of the first covered stent provided for Example 1; Figure 4 Schematic diagram of an open annular stent with U-shaped waves provided for Example 1; Figure 5 Schematic diagram of an open annular stent with V-shaped waves provided for Example 2; Figure 6 Structural schematic of the middle section of the stent body of the first form provided for Example 1 Figure 1 ; Figure 7 Structural schematic of the middle section of the stent body of the first form provided for Example 1 Figure 2 ; Figure 8 Structural schematic of the middle section of the stent body of the second form provided for Example 1 Figure 1 ; Figure 9 Structural schematic of the middle section of the stent body of the second form provided for Example 1 Figure 2 ; Figure 10 Structural schematic diagram of the second covered stent provided for Example 4; Figure 11 Structural schematic diagram of the tubular covering film provided for Example 4; Figure 12 Structural schematic diagram of the stent body in the first load diameter state and the crimped state provided for Example 4; Figure 13 Structural schematic diagram of the support monomer of the stent body in the first load diameter state and the second load diameter state provided for Example 4; Figure 14 OCT image view of the covered stent in the loaded state after implantation into a blood vessel provided for Example 4; Figure 15 Schematic of the microscopic morphology of the filamentous structure with oriented arrangement of the tubular covering film Figure 1 ; Figure 16 Schematic of the microscopic morphology of the filamentous structure with oriented arrangement of the tubular covering film Figure 2 ; Figure 17 Schematic diagram of the microscopic morphology of the filamentous structure with non-oriented arrangement of the tubular covering film; Figure 18It is a relatively flat film tube body in the first load diameter state of the covered stent; Figure 19 It is a schematic structural diagram of the balloon-expandable covered stent system provided in Example 5; Figure 20 It is a partial schematic diagram of a balloon-expandable covered stent system configured with prestress; Figure 21 It is Figure 20 a schematic diagram of the folding structure of the covered stent system in the undeployed state in Figure 22 It is Figure 20 a schematic diagram of the herringbone fold structure of the covered stent system in the undeployed state in Figure 23 It is a partial schematic diagram of the balloon forming a pillow structure with both ends convex relative to the middle in the undeployed balloon-expandable covered stent system Figure 1 ; Figure 24 It is a partial schematic diagram of the balloon forming a pillow structure with both ends convex relative to the middle in the undeployed balloon-expandable covered stent system Figure 2 ; Figure 25 It is a schematic structural diagram of a balloon-expandable covered stent delivery system provided in Example 5; Figure 26 It is the animal experiment image of the covered stent provided in Example 4 Figure 1 ; Figure 27 It is the animal experiment image of the covered stent provided in Example 4 Figure 2 ; Figure 28 It is Figure 27 the animal experiment image with a commercially available product as the control group in the animal experiment Figure 1 ; Figure 29 It is Figure 27 the animal experiment image with a commercially available product as the control group in the animal experiment Figure 2 ; Figure 30 It is the clinical image of the covered stent provided in Example 4; In the figure: 1000, the first covered stent; 1100, the stent body; 1010, the non-annealed stent; 1020, the annealed stent; 1030, the closed-ring stent; 1040, the open-ring stent; 1050, the connecting rod; 1060, the stent unit; 1200, the film body; 100. The second type of covered stent; 1. Tubular covering; 101. Inner covering layer; 102. Outer covering layer; 103. Distal end of the covered stent; 110. First load diameter state; 120. Load state; 130. Compressed and held state; 140. Second load diameter state; 111. Relatively flat tubular covering surface; 1300. Prestressed fold structure; 1301. Fold structure; 1302. Herringbone fold structure; 2. Stent body; 200. Annular stent; 210. First annular stent; 220. Second annular stent; 230. Third annular stent; 240. Fourth annular stent; 201. First load diameter support monomer; 202. Compressed and held state support monomer; 203. Second load diameter support monomer; 2101. First support monomer of the first annular stent; 2201. First support monomer of the second annular stent; 2202. Second support monomer of the second annular stent; 3. Elastic tube sleeve; 301. Distal end of the elastic tube sleeve; 302. Proximal end of the elastic tube sleeve; 4. Balloon; 401. Distal end of the balloon; 402. Proximal end of the balloon; 403. Inner wall of the balloon; 404. Outer wall of the balloon; 410. Distal end of the balloon catheter; 420. Tube body of the balloon catheter; 430. Proximal end of the balloon catheter; 5. Pillow structure. Detailed implementation manners

[0017] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0018] It should be noted that in the description of the present invention, terms indicating directions or positional relationships such as "upper", "lower", "left", "right", "inner", "outer", "front", "rear", "center", "longitudinal", "transverse", "length", "width", "thickness", "vertical", "horizontal", "top", "bottom", "clockwise", "counterclockwise", etc. are based on the directions or positional relationships shown in the drawings. This is only for convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third", "fourth" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, it should also be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "set", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0019] The object of the present invention is to provide a covered stent and a balloon-expandable covered stent system to solve the problems existing in the above-mentioned prior art, which can provide moderate support for blood vessels and effectively improve the problems of restenosis and stent collapse after the implantation of the existing covered stent.

[0020] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0021] Embodiment 1 As Figures 1 to 9 shown, this embodiment provides a first covered stent 1000, including a stent body 1100. The radial support strength of the middle section of the stent body 1100 is greater than that of the two end sections of the stent body 1100, so that the middle section of the stent can provide a high radial support force, and the two end sections can provide a low radial support force. The middle section is used to support the stenotic part, and the two end sections are used to support the normal blood vessel section. In this embodiment, the radial support strength of the stent body 1100 is optimized, so that the first covered stent 1000 can not only provide a high radial support force for the stenotic part, but also prevent the support force of the normal blood vessel section from being too large to stimulate the blood vessel wall or be difficult to fit the normal blood vessel wall, thereby preventing damage to the normal blood vessel section, improving the treatment effect and reducing complications. The middle section of the first covered stent 1000 can be one or a combination of a closed annular stent 1030 and an open annular stent 1040.

[0022] It should be noted that the middle section in this embodiment does not represent the strict geometric center, and the actual position of the middle section can be biased towards one end of the first covered stent 1000.

[0023] In some specific embodiments, such as Figure 1 As shown, the annular stents of the stent body 1100 are all closed annular stents 1030, the middle section of the stent body 1100 is a non-annealed stent 1010, and both end sections of the stent body 1100 are annealed stents 1020; the wall thickness of the stent in the middle section of the stent body 1100 is greater than the wall thickness of the stent in both end sections of the stent body 1100. Annealing treatment is performed on both end sections of the stent body 1100. Annealing treatment can optimize the crystal structure, reduce internal defects, maintain elasticity / high ductility, and avoid damaging normal blood vessels; the middle section of the stent body 1100 is not annealed to maintain high strength / relatively high radial support force and avoid the collapse and loss of the lumen of diseased blood vessels. Through the differential design of not annealing the middle section and annealing both end sections in this embodiment, the distribution optimization of the middle section providing high radial support force and both end sections providing low radial support force is achieved. Through the combined deployment of the annealed state and the non-annealed state, the balloon-expandable covered stent in this embodiment can adapt to changes in radial support force (that is, provide a covered stent that can adapt to changes in the pressure exerted by blood vessels), so as to meet the different requirements of blood vessels for the strength of radial support force along the axial direction / the length direction of the blood vessel.

[0024] In some specific embodiments, such as Figure 2 As shown, the middle section of the stent body 1100 includes at least two sequentially connected closed annular stents 1030, and both end sections of the stent body 1100 each include at least two sequentially arranged open annular stents 1040. Both end sections of the stent body 1100 are non-annealed stents 1010, and the middle section of the stent body 1100 is an annealed stent 1020. The middle section adopts a closed-loop structure, and the closed-loop structure can provide stable radial support; both end sections of the stent body 1100 adopt an open-loop structure, and the open-loop structure itself has flexibility. Combined with the combined deployment of the annealed state and the non-annealed state, the radial support ability of both end sections of the stent body 1100 can be reduced.

[0025] Specifically, the middle section of the stent body 1100 includes a plurality of annealed closed annular stents 1030 arranged sequentially along the length direction of the first covered stent 1000, and both end sections of the stent body 1100 include a plurality of non-annealed open annular stents 1040 arranged sequentially along the length direction of the first covered stent 1000.

[0026] In some specific embodiments, at least one connecting rod 1050 is disposed between two adjacent closed annular brackets 1030. The connecting rod 1050 can further enhance the supporting ability of the middle section of the bracket body 1100 and ensure high radial support for the narrow part.

[0027] In some specific embodiments, there is an included angle between the connecting rod 1050 and the axis of the bracket body 1100. The connecting rod 1050 is axially inclined relative to the bracket body 1100, increasing the stroke of the connecting rod 1050, which can reduce the stiffness during crimping and improve the crimping effect.

[0028] In some specific embodiments, the length direction of the connecting rod 1050 is parallel to the axis of the bracket body 1100.

[0029] In some specific embodiments, each open annular bracket 1040 includes a plurality of bracket units 1060. Each bracket unit 1060 is a U-shaped unit. The plurality of bracket units 1060 are connected end to end in sequence to form an annular bracket. The openings of two adjacent U-shaped units face in opposite directions, and the openings of the U-shaped units face the ends of the bracket body 1100.

[0030] In some specific embodiments, the material of the middle section of the bracket body 1100 is cobalt-chromium alloy, and the materials of both end sections of the bracket body 1100 are cobalt-chromium alloy.

[0031] In some specific embodiments, it further includes a film covering body 1200. One end section of the bracket body 1100, the middle section of the bracket body 1100, and the other end section of the bracket body 1100 are sequentially connected to the film covering body 1200. The film covering body 1200 may also include a filamentous structure arranged in an oriented manner. In the unexpanded state of the film covering body 1200, it may also include a prestressed fold structure 1300.

[0032] In some specific embodiments, the film covering body 1200 is an expanded polytetrafluoroethylene (ePTFE) membrane.

[0033] In some specific embodiments, one end section of the bracket body 1100, the middle section of the bracket body 1100, and the other end section of the bracket body 1100 are fixed to the film covering body 1200 by laser welding or by an adhesive.

[0034] In some specific embodiments, the closed-loop stent 1030 includes a plurality of diamond-shaped units connected in sequence to form a loop, and the diamond-shaped units of two adjacent closed-loop stents 1030 are arranged in a staggered manner. There are a plurality of connecting rods 1050 between two adjacent closed-loop stents 1030. One end of each connecting rod 1050 is fixedly connected to a diamond-shaped unit of one closed-loop stent 1030, and the other end of each connecting rod 1050 is fixedly connected to an adjacent diamond-shaped unit of the adjacent closed-loop stent 1030.

[0035] In some specific embodiments, the connecting rod 1050 is smoothly connected to the diamond-shaped unit it is connected to, so as to ensure the overall flexibility of the stent body 1100.

[0036] In some specific embodiments, the outer diameter of the middle section of the stent body 1100 is 5 mm - 8 mm, and the wall thickness of the middle section is 0.05 mm - 0.15 mm.

[0037] In some specific embodiments, the radial support force of the middle section of the first covered stent 1000 is ≥ 1.5 N / mm, and the radial support force of the two end sections of the first covered stent 1000 is ≤ 0.8 N / mm.

[0038] In some specific embodiments, at least one end of the stent body 1100 of the first covered stent 1000 is provided with an end stent, so that the first covered stent 1000 has a hybrid radial support performance along its length direction. The blood vessel lumen environment where the first covered stent 1000 is located (such as the common iliac artery and the internal iliac artery) often has a large blood flow rate and a high pulse intensity; under the combined action of fluid mechanics, the first covered stent 1000 is prone to problems such as displacement after implantation and poor wall apposition. Optimize the radial support performance of the first covered stent 1000 along its length direction to form a hybrid radial support performance. For example, the first covered stent 1000 is deployed at intervals of a strong radial support performance stent segment - a weak radial support performance stent segment - a strong radial support performance stent segment along its length direction; another example is that the first covered stent 1000 is sequentially distributed with high ductility regions - high strength regions - high ductility regions - high strength regions, or high strength regions - high ductility regions - high ductility regions - high strength regions along its length direction. The radial support performance of the first covered stent 1000 is not limited to the above forms, and the radial support of the first covered stent 1000 can be set according to the location and number of vascular lesions to form different combinations of hybrid radial support performances. It should be noted that the strong radial support performance stent segments and high strength regions of the first covered stent 1000 are used to support the diseased blood vessels, and the weak radial support performance stent segments and high ductility regions of the first covered stent 1000 are used to support the normal blood vessels. There are at least three technical routes to achieve the above effects: The first technical route is that when the wall thickness and wall width dimensions (i.e., geometric dimensions) of the same stent unit morphology structure (such as all open or all closed) are the same / unchanged, the stent units 1060 at both ends of the covered stent are annealed (to maintain elasticity / high ductility and avoid damaging normal blood vessels), and the stent units 1060 in the middle part are not annealed (to maintain high strength / relatively high radial support force and avoid the collapse and loss of the lumen of the diseased blood vessels); The second technical route is that when the same stent unit morphology structure is in the annealed state, by changing the wall thickness and wall width dimensions of the stent unit 1060, the radial support force / radial support performance between each stent unit 1060 is made different; The third technical route is a hybrid optimization, with differences in the morphology structure between stent units 1060, differences in the metal crystal form between stent units 1060 (i.e., a combination treatment of annealed state and non-annealed state), and differences in the geometric dimensions of the morphology structure between stent units 1060 (such as increasing the wall thickness or decreasing the wall thickness); thereby realizing that the covered stent has a hybrid radial support performance along its length direction (in other words, thereby realizing that the covered stent has a hybrid radial support force value along its length direction).

[0039] It should be noted that the annealing treatment method is generally as follows: The cobalt-chromium alloy is heated to 800 - 1000 °C and held for 1 - 2 hours under the protection of an inert gas, and then slowly cooled to eliminate processing stress, promote dislocation movement and crystal defect repair, form a uniform annealed structure, and maintain high ductility. Non-annealing treatment means that the cobalt-chromium alloy is directly cold-worked into shape, retaining the work-hardening effect and maintaining a high dislocation density and crystal defects.

[0040] Design of the stent unit in the middle section area of the covered stent: Compared with the open structure, using a closed stent unit (such as a continuous annular support unit) can provide stable radial support and enhance the ability of the middle section to resist vascular stenosis.

[0041] Design of the stent unit in the two end section areas of the covered stent: Compared with the closed type, using an open type (such as a V-shaped or U-shaped support unit) can reduce the radial support force at both ends and facilitate fitting to the normal blood vessel wall.

[0042] For the stent unit 1060 with the same structural form (both are closed or both are open), its geometric size directly affects the radial support force value of the stent unit 1060; further increasing the value relative to the original size value can increase the radial support force value of the stent unit 1060.

[0043] Embodiment 2 As Figures 1 to 9 shown, this embodiment provides a first covered stent 1000. Each open annular stent 1040 in this embodiment includes a plurality of stent units 1060. Each stent unit 1060 is a V-shaped unit, and the plurality of stent units 1060 are connected end to end in sequence to form an annular stent. The openings of two adjacent V-shaped units face in opposite directions, and the openings of the V-shaped units face the ends of the stent body 1100.

[0044] The other structures, connection relationships, and working principles of the first covered stent 1000 provided in this embodiment are the same as those in Embodiment 1.

[0045] Embodiment 3 This embodiment provides a method for manufacturing a covered stent, including the following steps: Obtain the stent body 1100, and make the radial support strength of the middle section of the stent body 1100 greater than the radial support strength of the two end sections of the stent body 1100.

[0046] In some specific embodiments, it further includes: respectively obtaining the middle section of the stent body 1100 and the two end sections of the stent body 1100, making the annular stents of the stent body 1100 all closed annular stents 1030, and performing annealing treatment on the two end sections of the stent body 1100.

[0047] In some specific embodiments, the method for obtaining the middle section and the two end sections of the stent body 1100 includes: performing laser cutting or etching on a metal tube, preferably a cobalt-chromium alloy tube, to process at least two open-ended annular stents 1040 at the two end sections of the metal tube and at least two closed annular stents 1030 at the middle section of the metal tube.

[0048] In some specific embodiments, the method for annealing the two end sections of the stent body 1100 includes: under the protection of an inert gas, heating the two end sections of the stent body 1100 to 800°C - 1000°C and holding for 1 - 2 hours, and then slowly cooling. By controlling the heating temperature and heating time, it is ensured that the processing stress in the middle section can be eliminated, dislocation movement and crystal defect repair can be promoted, and a uniform annealed microstructure can be formed.

[0049] In some specific embodiments, it further includes: cutting expanded polytetrafluoroethylene (ePTFE) film into appropriate sizes, and covering the ePTFE film on the surface of the stent through heat shrinkage or bonding processes, with emphasis on strengthening the fixation of the ePTFE film in the middle section.

[0050] In some specific embodiments, it further includes: cutting the expanded polytetrafluoroethylene (ePTFE) film into a tubular shape, sleeving the tubular film on the surface of the stent body 1100, and using a heat shrinkage device to perform heat shrinkage fixation of the tubular film and the stent body 1100 at 200°C - 250°C. An adhesive is added in the middle section to enhance the adhesion between the middle section of the stent body 1100 and the tubular film.

[0051] In some specific embodiments, after the stent body 1100 and the film-covered body 1200 are assembled, performance testing is performed on the first film-covered stent 1000 to ensure that the distribution of the radial support force of the first film-covered stent 1000 meets the design requirements.

[0052] In some specific embodiments, a laser cutting machine is used to engrave continuous annular support units in the middle section and stent units 1060 at both ends on the pipe.

[0053] In some specific embodiments, the method for annealing the middle section of the stent body 1100 includes: placing the two end sections in a vacuum annealing furnace, introducing argon for protection, heating the annealing furnace to 900°C, holding for 1.5 hours, and then cooling to room temperature with the furnace.

[0054] In some specific embodiments, a radial support force tester is used to measure the radial support forces of the middle section and the two end sections of the first film-covered stent 1000, ensuring that the radial support force of the middle section ≥ 1.5 N / mm and the radial support force of the two end sections ≤ 0.8 N / mm.

[0055] In some specific embodiments, the wall attachment property and flexibility of the first covered stent 1000 are verified through in vitro simulated blood vessel dilation experiments.

[0056] Example 4 As Figures 10 to 30 shown, this embodiment provides a second covered stent 100, which includes a stent body 2 connected by a tubular covering film 1. The second covered stent 100 has a non-loaded state with a zero compression diameter (in the non-loaded state, the support monomers of the annular stent 200 are usually diamond-shaped), and a loaded state 120 with a compression ratio relative to the non-loaded state for supporting the blood vessel to restore blood flow; when the compression ratio of the second covered stent 100 is 10%, the numerical range of the radial support force of the second covered stent 100 is 2.0 N / mm - 6.0 N / mm. By setting the radial support force of the second covered stent 100 with a compression ratio of 10% to 2.0 N / mm - 6.0 N / mm, when the second covered stent 100 is placed in the blood vessel lumen in the loaded state 120 to support the blood vessel, it can provide appropriate support for the blood vessel and effectively improve the problems of in-stent restenosis and stent collapse after the implantation of the existing second covered stent 100; As Figures 26 to 29 shown, the implantation experiment of animals verifies that the second covered stent 100 has excellent support performance compared with commercially available ordinary balloon-expandable covered stents; 90 days after implantation, the second covered stent 100 has no collapse (see Figure 27 , DSA and OCT images 90 days after the operation, the second covered stent 100 as a whole and the arrow-pointed part both maintain a relatively complete stent cavity, with a low lumen loss rate and a blood vessel stenosis rate of about 8.6%). In the control group of commercially available products, obvious blood vessel stenosis and stent collapse occurred (see Figure 29 , DSA and OCT images 90 days after the operation, the whole of the control group of commercially available products and the arrow-pointed part showed collapse, with a high lumen loss rate and a blood vessel stenosis rate of about 17.4%).

[0057] It should be noted that the zero compression diameter refers to the natural diameter of the second covered stent 100 when it is completely released (not compressed or stretched by external forces). The test of the radial support force of the second covered stent 100 needs to be carried out in accordance with "YY / T 1660-2019 Test Method for Radial Load of Balloon-expandable and Self-expandable Stents", that is, it is necessary to test the radial support force of the second covered stent 100 when the compression ratio is 10%. The second covered stent 100 adopts a design without connection bridges and has good flexibility; the support monomers adopt a diamond ring design, and a structural unit with high radial strength, fatigue resistance and post-dilation performance is obtained through simulation; such a structural unit can show good anti-collapse performance in actual applications and improve the patency performance of blood vessels. The results of animal experimental studies on the second covered stent 100 and commercially available products show that the second covered stent 100 has better blood vessel patency and anti-stent collapse performance.

[0058] In some specific embodiments, the diameter of the second covered stent 100 is approximately 10% larger than the diameter of the normal blood vessel near the blood vessel to be supported (the blood vessel at the stenotic site). After being implanted into the blood vessel, the second covered stent 100 contacts and is compressed by the normal blood vessel after being released. After the second covered stent 100 is released, it supports the stenotic blood vessel under the expansion action of the balloon 4, so that the diameter of the stenotic blood vessel is approximately the same as or the same as that of the normal blood vessel. When the second covered stent 100 is placed in the blood vessel for support, the compression rate is approximately 10%.

[0059] As a preferred embodiment, when the compression rate of the second covered stent 100 is 10%, the numerical range of the radial supporting force of the second covered stent 100 is 3.0 N / mm - 4.5 N / mm.

[0060] In some specific embodiments, at the starting moment when the second covered stent 100 is deployed in the blood vessel lumen in the loaded state 120, the cross-sectional area of the hollow cavity of the second covered stent 100 is the immediate cross-sectional area; when the second covered stent 100 is deployed in the blood vessel lumen and maintained for 90 days, the cross-sectional area of the hollow cavity of the second covered stent 100 is the first cross-sectional area. The ratio of the average value of the first cross-sectional area of the second covered stent 100 to the average value of the immediate cross-sectional area of the second covered stent 100 is greater than 0.7, that is, in this embodiment, the problems of restenosis and stent loss of the lumen after the implantation of the second covered stent 100 are significantly improved. Further, when the covered stent is deployed in the blood vessel lumen and maintained for 90 days, the ratio of the average value of the first cross-sectional area of the covered stent to the average value of the immediate cross-sectional area of the covered stent is greater than 0.85.

[0061] In some specific embodiments, the stent body 2 is an alloy stent; the alloy material components of the stent body 2 include cobalt, titanium and boron. The alloy stent using this kind of material can improve the supporting performance of the stent body 2 and improve the problem of collapse of the stent body 2.

[0062] As a preferred embodiment, the material of the stent body 2 is MP35N nickel-cobalt alloy.

[0063] In some specific embodiments, the stent body 2 includes a plurality of annular stents 200 longitudinally spaced along the tubular film 1; the tubular film 1 has a microscopic morphology of a filamentous structure arranged in an oriented manner, and the force on at least part of the annular stents 200 can be transmitted to adjacent annular stents 200 through the filamentous structure of the tubular film 1. The filamentous structure enables stress to be conducted longitudinally along the second film-covered stent 100, so that the force on the annular stent 200 can be dispersed to other adjacent annular stents 200, thereby improving the mechanical properties of the second film-covered stent 100 and alleviating the problem of stent collapse. Further, the oriented filamentous structure helps / synergistically forms a prestressed fold structure 1300 during the process of the second film-covered stent 100 being compressed and clamped by the delivery system, and alleviates the problem of shortening of the longitudinal length of the second film-covered stent 100 during the delivery and release of the second film-covered stent 100.

[0064] In some specific embodiments, the tubular film 1 at least includes an inner film layer 101 and an outer film layer 102, and the stent body 2 is fixedly connected between the inner film layer 101 and the outer film layer 102; the inner film layer 101 and the outer film layer 102 have different microscopic morphologies. With such an arrangement, it promotes the mechanical anisotropy of the tubular film 1, which can not only take into account the bending performance of the second film-covered stent 100, but also improve the force dispersion performance of the local film of the second film-covered stent 100 after being pressed by blood vessels, so that it can maintain the initial shape of the implanted blood vessel (such as Figure 26 the circular lumen in the immediate postoperative OCT, and Figure 27 the circular lumen in the OCT at 90 days after surgery, with basically no or little change), and avoid lumen collapse (such as Figure 28 the circular lumen in the immediate postoperative OCT, and Figure 29 the irregular cavity with the circular lumen in the OCT at 90 days after surgery collapsing into a non-circular lumen), and maintain the initial lumen rate.

[0065] In some specific embodiments, the inner film layer 101 has a microscopic morphology of a filamentous structure arranged in an oriented manner; the outer film layer 102 has a microscopic morphology of a filamentous structure, and the filamentous structure of the outer film layer 102 is shorter than that of the inner film layer 101. The filamentous structure can increase the surface roughness of the outer film layer 102. By contacting the rough outer wall of the outer film layer 102 with the blood vessel wall and providing support for the blood vessel, it can increase the anchoring of the outer film layer 102 to the vascular intima and prevent the displacement of the second film-covered stent 100 after implantation.

[0066] In some specific embodiments, the outer film layer 102 has a microscopic morphology of a filamentous structure arranged in a non-oriented manner.

[0067] In some specific embodiments, the stent body 2 includes a plurality of annular stents 200 longitudinally spaced along the tubular film 1; the filamentous structure of the film between two adjacent annular stents 200 extends longitudinally along the tubular film 1. The filamentous structure of the tubular film 1 can improve the longitudinal support strength between the annular stents 200 and reduce the probability of longitudinal shortening of the second film-covered stent 100 during the release of the second film-covered stent 100 when interacting with the balloon-expandable film-covered stent system.

[0068] In some specific embodiments, both ends of the filamentous structure of at least a part of the tubular film 1 are respectively connected to two annular stents 200. Specifically, both ends of the filamentous structure are connected to two adjacent annular stents 200 through the film.

[0069] In some specific embodiments, a plurality of filamentous structures of the film tube body between two annular stents 200 are arranged circumferentially along the second film-covered stent 100, that is, a plurality of filamentous structures are provided between two adjacent annular stents 200 to improve the support effect.

[0070] In some specific embodiments, each annular stent 200 is cut from an alloy pipe; each annular stent 200 has a first load diameter that sleeves on the outer surface of the inflated balloon and expands to be greater than 10% of the blood vessel diameter; when each annular stent 200 is in the first load diameter state 110, the second film-covered stent 100 has a first load state; the second film-covered stent 100 has a delivery state that sleeves on the outer surface of the non-inflated balloon; the ratio of the longitudinal length value of the second film-covered stent 100 in the first load state (expanded state / unfolded state) to the longitudinal length value of the second film-covered stent 100 in the delivery state (compressed state 130 / unfolded state) is greater than 0.95; when the second film-covered stent 100 is in the first load state, at least a part of the tubular film 1 is stretched by the annular stent 200 without elastic deformation (as Figure 18 shown, in the diamond-shaped area of the support monomer with the first load diameter, a relatively flat tubular film surface 111 is presented). When the annular stent 200 expands the narrow part, it usually covers the normal blood vessels near the narrow lesion. The vascular reaction forces on the blood vessels in the narrow part and the normal part are different. There are a plurality of annular stents 200 on the whole stent, and some annular stents 200 may expand too much, resulting in elastic deformation of the film. The second film-covered stent 100 is delivered in the compressed state 130. By reasonably setting the longitudinal length of the second film-covered stent 100 in the delivery state and enabling the annular stent 200 to support the tubular film 1 and at least a part of the tubular film 1 not to produce elastic deformation when the second film-covered stent 100 is released, the problem of longitudinal shortening of the second film-covered stent 100 during the release of the second film-covered stent 100 when interacting with the balloon-expandable film-covered stent system is improved.

[0071] In some specific embodiments, each annular stent 200 further has a second load diameter greater than the diameter of the alloy pipe; a part of the tubular film 1 can be expanded by the annular stent 200 in the second load diameter state 140 and undergoes elastic deformation. When the balloon 4 expands, the annular stent 200 can be expanded to reach the second load diameter. As Figure 13 shown, generally, the circumferential length L of the first load diameter support monomer 201 in the first load diameter state 110 is less than the circumferential length L of the second load diameter support monomer 203 in the second load diameter state 140.

[0072] In some specific embodiments, as Figure 12 and Figure 13 shown, each annular stent 200 includes a plurality of frames (the first load diameter support monomer 201, the crimping state support monomer 202, the second load diameter support monomer 203) arranged circumferentially around the tubular film 1 and connected by connecting rods. The frame includes a seam with a variable shape surrounded by a continuous metal boundary; the film between two annular stents 200 has a circumferentially continuous tube body.

[0073] The peripheral balloon-expandable covered stent system generally consists of a second covered stent 100 and a delivery system. The stent is pre-mounted on the balloon 4 of the delivery system. The stent is composed of a balloon-expandable cobalt-based alloy stent ring and a fluoropolymer. The delivery system consists of a tip, a radiopaque ring, an inner tube, a balloon 4, a catheter, a catheter reinforcement, and a catheter hub. The two radiopaque rings are located inside the balloon 4 and near both ends of the stent, marking the effective length of the balloon 4 and facilitating stent placement. The delivery system is compatible with a 0.035-inch (0.89 mm) guide wire and can be used for initial stent placement and post-stent dilation. The pre-mounted stent system is available in a variety of stent diameters and lengths. The lengths of the pre-mounted delivery system catheters are 75 cm and 135 cm. The peripheral balloon-expandable covered stent system is used to treat common iliac artery and external iliac artery stenosis and / or occlusive lesions.

[0074] Clinical usage examples of the covered stent (as Figure 30 shown): I) Vascular treatment 1. Establishing a vascular access a) After appropriate local anesthesia, select a suitable blood vessel to establish an access. If possible, it is best to choose the percutaneous Seldinger puncture technique. An epidermotomy can be performed when necessary.

[0075] b) Insert a blood vessel sheath of appropriate size into the blood vessel using standard techniques.

[0076] 2. Angiography and measurement Through angiography, the lesion location or stenosis segment is evaluated and marked under X-ray, and the location of vascular stenosis or occlusive lesions is observed. Measure the diameter and length of the target lesion to determine the specifications of the required stent. When necessary, use a measuring wire or catheter for measurement.

[0077] 3. Percutaneous Transluminal Angioplasty (PTA) a) It is recommended to pre-dilate the lesion site to facilitate the passage of the stent system.

[0078] b) Inflate the angioplasty balloon 4 to the nominal pressure. Ensure that the balloon 4 is fully expanded within the lesion site. Note: Carefully mark the boundaries of the angioplasty treatment segment to ensure complete coverage by the stent.

[0079] c) After the balloon 4 is deflated, use angiography to evaluate the results. Measure the vessel diameter, the length of the lesion site, and the percentage of residual stenosis for reference.

[0080] 4. Stent Size Determination and Selection Before opening the sterile package and removing the contents, check whether the diameter and length of the stent and the effective length of the delivery system are correct.

[0081] ● When selecting a stent of appropriate size, the blood vessel must be carefully evaluated.

[0082] Stenotic or occlusive lesion site: To reduce the likelihood of vascular injury, select a stent with an outer diameter approximately 10% larger than the vessel diameters at the proximal and distal ends of the stenosis. To prevent stent migration, during the period from the initial deployment of the device to post-deployment dilation, care should be taken to ensure that the device is fully in contact with the vessel wall.

[0083] ● Confirm that the delivery system catheter has sufficient length to reach the treatment site.

[0084] II) Stent Preparation 1. Carefully check whether the package is damaged. If it has passed the shelf life, do not use this product. Open the packaging box and take out the sterile inner packaging bag containing the stent. Start from a corner and tear the edge of the inner packaging bag, then gently take out the stent system.

[0085] 2. Pre-use inspection: ● Before using this product, carefully check whether all materials and equipment used in the operation are bent, kinked, or otherwise damaged.

[0086] ● Do not use any damaged or defective equipment and materials.

[0087] ● If the sterile packaging is damaged or the stent system is damaged, do not use this product.

[0088] 3. Before loading the catheter onto the guide wire, the distal end of the stent system can be bent into a circular shape to make the delivery system easier to track. During the bending process, care should be taken to ensure that the metal stent rings do not deform, misalign, or become damaged.

[0089] 4. Preparation of the catheter of the stent delivery system: a) Connect a heparinized saline syringe to the guide wire port of the stent system and flush the delivery catheter until a steady stream of water flows out of the catheter tip.

[0090] b) After flushing the catheter, remove the syringe.

[0091] c) Prepare a pressurizing device / syringe with diluted contrast agent (a 1:1 mixture of contrast agent and saline), or a medium considered suitable by the physician.

[0092] d) Connect the pressurizing device / syringe to a three-way stopcock (if required), and then connect it to the inflation port of the stent system.

[0093] e) Open the three-way stopcock leading to the stent system, hold the distal balloon 4 with its tip downward, making it lower than the level of the pressurizing device / syringe, and pull the plunger of the pressurizing device / syringe to create a negative pressure for 20 - 30 seconds. Carefully release the plunger to fill with contrast agent without applying positive pressure, as this may cause partial deployment of the stent.

[0094] f) Close the three-way stopcock leading to the stent system; remove all air from the pressurizing device / syringe.

[0095] g) Repeat steps e) and f) until all air is expelled. If there are still air bubbles, do not use the stent system.

[0096] h) Connect the prepared pressurizing device / syringe to the three-way stopcock and open the three-way stopcock.

[0097] 5. Once the surface of the stent has been moistened, do not allow it to dry.

[0098] III) Insertion and positioning of the stent 1. Select a vascular sheath with a matching size and no kinks. It is recommended to use a vascular sheath with a length sufficient to pass through the lesion site. Using a vascular sheath can minimize the risk of the stent detaching from the balloon 4 during tracking. Insert the stent into the target lesion site using standard interventional techniques.

[0099] 2. Ensure that the guide wire has a diameter of 0.035" (0.89 mm).

[0100] 3. Ensure that the position of the guide wire is maintained beyond the target lesion site while removing the balloon catheter. Avoid re-insertion until the operation is completed.

[0101] 4. Insert the distal end of the guide wire into the proximal end of the stent system, keeping the tube body as straight as possible. Carefully advance the stent along the guide wire slowly (about 0.5 cm each time), through the hemostatic valve and the vascular sheath, and into the access vessel. Note: If excessive resistance is felt when guiding the stent through the hemostatic valve, withdraw it and check whether the product is damaged. If the stent is damaged or the covered stent is displaced relative to the radiopaque ring marker on the delivery system as observed under X-ray, do not use it.

[0102] 5. Under X-ray guidance, carefully advance the delivery system along the guide wire. If excessive resistance is felt, withdraw the whole product and the vascular sheath together.

[0103] 6. Under direct X-ray observation, position the stent at the location straddling the target lesion site. Using the proximal and distal radiopaque ring markers (indicating the effective length of balloon 4) of the delivery system and the radiopaque stent as reference points, position the stent at the lesion site. Note: After the stent is deployed, due to longitudinal shortening, both ends of the stent will be within the effective length of balloon 4. When selecting a stent, the stent shortening factor should be taken into account to cover the expected lesion site. During the positioning process, confirm that the stent is still centered within the marker band and has not fallen off. Do not deploy the stent unless it is exactly centered on balloon 4 and correctly positioned within the target lesion site. If the stent is within the lesion site but not in the optimal position, it should be carefully repositioned or withdrawn.

[0104] If a PTA procedure is performed, the stent length should cover the entire vascular segment treated by balloon angioplasty. In appropriate cases, it is recommended that the stent extend at least 1 cm beyond the proximal and distal margins of the lesion site.

[0105] 7. When the optimal positioning is confirmed under X-ray, start to deploy the stent. Note: After the stent has been fully inserted, do not withdraw the stent back into the vascular sheath. If the stent needs to be withdrawn, withdraw it to a position close to the vascular sheath but do not enter the sheath. Then the stent system and the vascular sheath can be removed simultaneously. After removal, do not use it again. Do not attempt to pull the partially expanded or unexpanded stent system back into the vascular sheath, as this may cause the stent to fall off from balloon 4. Carefully observe whether the stent has fallen off or moved, and at the same time try to withdraw the unexpanded stent through the vascular sheath.

[0106] IV) Deployment of the Stent 1. Keep the delivery system stably at the hemostatic valve of the vascular sheath, maintaining the relative positions of the delivery system catheter and the vascular sheath with respect to the patient, reducing catheter movement during deployment to ensure accurate stent positioning.

[0107] 2. To reduce the likelihood of vascular injury, the outer diameter of the stent selected should be approximately 10% larger than the vascular diameters at the proximal and distal ends of the stenosis. Use a pressurizing device to slowly inflate the stent system to the pressure required to reach the desired diameter, and maintain the inflation pressure for about 15 seconds. To reduce the impact of any lumen damage or stent retraction caused by the lesion site, a higher inflation pressure may be required, but the pressure should not exceed the rated burst pressure. If the stent size is too large relative to the vascular diameter, it may cause vascular injury; if the stent size is too small, it may cause stent migration. The compliance table provided on the packaging label is generated under idealized in vitro conditions and does not take into account the characteristics of the in vivo lesion site, the variability of blood vessels, and different patients. Therefore, the compliance chart should be used as a general guide, and the user should confirm the stent diameter and length during the inflation and release of balloon 4 and through angiography.

[0108] 3. After deploying the stent, use a pressurizing device to manually deflate balloon 4 slowly to ensure proper re-recovery of balloon 4. Before withdrawal, allow sufficient time for balloon 4 to deflate completely and observe under X-ray that balloon 4 has deflated completely.

[0109] 4. Maintain proper vascular sheath support and very slowly withdraw balloon 4. Observe under X-ray to ensure that balloon 4 detaches from the stent. If resistance is encountered during the attempt to withdraw, do not force it out. Determine and correct the cause of the resistance under X-ray in combination with conventional techniques, and then continue.

[0110] 5. Use angiography techniques to confirm the position and deployment of the stent. For optimal results, the stent should cover the entire lesion site. Observe using X-ray to facilitate comparison of the proximal and distal ends of the stent with the reference vascular diameter and correctly judge the optimal post-dilation stent diameter.

[0111] 6. If re-sizing is required, use standard interventional techniques to re-advance the delivery system catheter or another balloon catheter of appropriate size into the area where the stent is placed.

[0112] 7. Under X-ray observation, inflate balloon 4 to the nominal pressure, not exceeding the rated burst pressure. When using another balloon 4 for post-deployment dilation, select a balloon 4 length shorter than the length of the deployed stent. Do not expand balloon 4 beyond the ends of the stent and into healthy blood vessels, as it may cause restenosis and subsequent failure. Deflate balloon 4 and operate according to the previous instructions.

[0113] 8. Re-confirm the stent position and angiography results. Inflate again until the desired effect is achieved.

[0114] (V) After stent deployment 1. While maintaining the negative pressure within the balloon 4 and the position of the guide wire across the treatment lesion site, carefully withdraw the delivery system from the body via the vascular sheath. When withdrawing the balloon 4 via the catheter, some resistance may be felt.

[0115] Note: During the process of withdrawing the catheter, if the balloon 4 gets stuck on the leading edge of the vascular sheath, gently moving the catheter back and forth slightly may help disengage it. If necessary, the delivery system and the vascular sheath can be withdrawn together as a whole. Excessive or forceful pulling during the catheter withdrawal process may damage the delivery catheter or the vascular sheath.

[0116] 2. It is recommended to perform an angiography one last time to evaluate vascular patency.

[0117] 3. When the clinical conditions are suitable, withdraw the vascular sheath and perform hemostasis at the puncture site.

[0118] Example 5 As Figures 19 to 25 shown, this example provides a balloon-expandable covered stent system, including an elastic tube sleeve 3, a balloon 4, a mandrel (such as the balloon catheter body 420, the balloon catheter body 420 having a balloon catheter distal end 410 and a balloon catheter proximal end 430), and the second covered stent 100 in Example 5. The second covered stent 100, the elastic tube sleeve 3, the balloon 4, and the mandrel are sleeved and arranged in sequence from outside to inside; both ends of the balloon 4 are hermetically and fixedly connected to the mandrel and can be filled and expanded through the liquid passage of the mandrel; the proximal end 302 of the elastic tube sleeve is fixedly connected to the mandrel, or the proximal end 302 of the elastic tube sleeve is fixedly connected to the proximal end 402 of the balloon; the distal end 301 of the elastic tube sleeve is movably sleeved on the balloon; the radially contracted / constricted / unexpanded second covered stent 100 can be removably sleeved on the elastic tube sleeve 3. The elastic tube sleeve 3 can provide an elastic carrier with a relatively thickness-depressible property for the second covered stent 100, enabling the second covered stent 100 to be tightly loaded / constrained on the balloon-expandable covered stent system (delivery system), that is, the second covered stent 100 can be recessed to a certain extent within the outer wall of the elastic tube sleeve. When the loading is completed, the second covered stent 100 will have a radial rebound of 0.1 - 0.2 mm. At this time, the recessed part of the elastic tube sleeve 3 under the action of the second covered stent 100 can also have an appropriate rebound, enabling better contact between the second covered stent 100, the elastic tube sleeve 3, and the balloon 4, ensuring sufficient friction between the second covered stent 100, the elastic tube sleeve 3, and the balloon 4. When the second covered stent 100 is withdrawn from the delivery sheath tube, it can reduce the displacement and shortening in the longitudinal direction of the second covered stent 100; when the balloon 4 expands, it causes the second covered stent 100 to expand radially. Due to the friction between the elastic tube sleeve and the second covered stent 100, it reduces the displacement and shortening in the longitudinal direction of the second covered stent 100 during the expansion process.

[0119] In some specific embodiments, the balloon-expandable covered stent system can expand from an unexpanded state with an unexpanded diameter (as shown in Figure 19 ), to an expanded state with an expanded diameter (as shown in Figure 25 ); as shown in Figure 20 , in the balloon-expandable covered stent system in the unexpanded state, the covered stent is configured to have prestress, or the elastic tube sleeve is configured to have prestress, or the balloon 4 is configured to have prestress; for example, the prestressed fold structure 1300 (including the fold structure 1301 and the herringbone fold structure 1302) formed between the annular stents 200 (the first annular stent 210, the second annular stent 220, the third annular stent 230, the fourth annular stent 240), the prestressed fold structure 1300 is circumferentially and longitudinally spaced along the second covered stent 100; for another example, the cavity at the end of the balloon 4 (near the balloon distal end 401 or the balloon proximal end 402) pre-stores gas or liquid, so that the end section of the balloon 4 bulges / swells slightly (usually, the height of the bulge / swelling is level with or higher than the height of the end of the second covered stent 100), to form the pillow structure 5 (pillow); the length between the two ends of the second covered stent 100 is less than the length between the two ends of the balloon 4, to ensure that one end of the balloon 4 can extend relative to the end edge of the second covered stent 100, to form the pillow structure 5 (pillow).

[0120] In some specific embodiments, the prestress design is also applied to the balloon delivery system / structure without an elastic tube sleeve. The balloon delivery system / structure without an elastic tube sleeve is a common (or commercially available) balloon catheter; that is, the covered stent on the balloon catheter has the prestressed fold structure 1300, or the balloon 4 has the pillow structure 5.

[0121] In some specific embodiments, as shown in Figure 21As shown, in the unexpanded state, the covered stent has a number of pleated structures 1301 formed by prestress and developing longitudinally. Generally, the pleated structure 1301 extends from one end of an annular stent support monomer to the gap between another annular stent support monomers; for example, the pleated structure 1301 extends from one end of the first support monomer 2101 of the first annular stent 210 to the gap between the first support monomer 2201 of the second annular stent 220 and the second support monomer 2202 of the second annular stent 220. It can be understood that, like the crease of origami, the crease area of the pleated structure 1301 can enhance the longitudinal compression resistance compared to the flat covering film (for example, the relatively flat tubular covering film surface 111), that is, enhance the anti-shortening performance of the second covered stent 100. Generally, the size of one end of a single pleated structure 1301 close to the distal end 103 of the covered stent is smaller than the size of the end far from the distal end 103 of the covered stent.

[0122] In some specific embodiments, during the deployment process of the balloon-expandable covered stent system, the pleated structure 1301 can inhibit the longitudinal shortening of the covered stent.

[0123] In some specific embodiments, as Figure 19 , Figure 23 and Figure 24 shown, the balloon 4 in the unexpanded state has a pillow structure 5. As Figure 19 shown, the end of the balloon 4 (close to the distal end 401 or the proximal end 402 of the balloon) pre-stores gas or liquid in the cavity, causing the end segment of the balloon 4 to slightly bulge / protrude to form the pillow structure 5. As Figure 23 shown, generally, when passing through the sheath channel constructed by the percutaneous Seldinger puncture technique or the blood vessel lumen, the pillow structure 5 of the balloon-expandable covered stent system will be squeezed and deformed by the sheath wall or the blood vessel wall, forcing the pre-stored gas or liquid in the balloon 4 to be squeezed and filled into the balloon segment covered by the second covered stent 100, lifting the balloon wall in this area, making the inner wall 403 of the balloon away from the balloon catheter body 420, and the outer wall 404 of the balloon applying a force to the inner wall of the elastic tube sleeve 3, dynamically compensating for the force between the inner wall of the second covered stent 100 and the outer wall of the elastic tube sleeve 3 (or filling the newly generated gap between the inner wall of the second covered stent 100 and the outer wall of the elastic tube sleeve 3), and inhibiting the second covered stent 100 from being dislodged.

[0124] In some specific embodiments, as Figure 19 shown, in the unexpanded state of the balloon-expandable covered stent system, gas or liquid is pre-stored in the cavity of the balloon 4 to form a pillow structure 5 with the two ends (such as the distal end 401 or the proximal end 402 of the balloon) protruding relative to the middle.

[0125] In some specific embodiments, during the process of the balloon-expandable covered stent system delivering the second covered stent 100 into the target blood vessel lumen, the pillow structure 5 of the balloon 4 can prevent the second covered stent 100 from being detached from the balloon-expandable covered stent system.

[0126] In the embodiments of the specification of the present invention, various listed components including the covering film, the annular stent, and the delivery system can be freely combined into a balloon-expandable covered stent system according to actual use. The covered stent provided by the present invention is used to treat stenosis and / or occlusive lesions of the common iliac artery and the external iliac artery.

[0127] In the present invention, specific examples are used to illustrate the principle and implementation manners of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A covered stent, characterized in that: It includes a stent body, and the radial support strength of the middle section of the stent body is greater than that of the two end sections of the stent body.

2. The covered stent according to claim 1, wherein: The middle section of the stent body is a non-annealed stent, and both end sections of the stent body are annealed stents; the wall thickness of the stent in the middle section of the stent body is greater than that of the two end sections of the stent body.

3. The covered stent according to claim 1, wherein: The middle section of the stent body includes at least two sequentially connected closed-loop stents, and both end sections of the stent body include at least two sequentially arranged open-loop stents; the two end sections of the stent body are non-annealed stents, and the middle section of the stent body is an annealed stent.

4. The covered stent according to claim 3, wherein: At least one connecting rod is arranged between two adjacent closed-loop stents.

5. The covered stent according to claim 4, characterized in that: There is an included angle between the connecting rod and the axis of the stent body.

6. The covered stent according to claim 3, wherein: Each open-loop stent includes a plurality of stent units, and each stent unit is a U-shaped unit or a V-shaped unit, and the plurality of stent units are sequentially connected end to end to form a loop stent.

7. The covered stent according to claim 1, wherein: The material of the middle section of the stent body is cobalt-chromium alloy, and the materials of both end sections of the stent body are cobalt-chromium alloy.

8. A method for preparing a covered stent, characterized in that: It includes the following steps: obtaining a stent body and making the radial support strength of the middle section of the stent body greater than that of the two end sections of the stent body.

9. A method for preparing a covered stent according to claim 8, characterized in that: It also includes: Obtaining the middle section of the stent body and the two end sections of the stent body respectively, and performing annealing treatment on the two end sections of the stent body.

10. A method for preparing a covered stent according to claim 9, characterized in that: The obtaining methods of the middle section of the stent body and the two end sections of the stent body include: performing laser cutting or etching on a metal tube to process at least two open-loop stents at the two end sections of the metal tube and processing at least two closed-loop stents at the middle section of the metal tube.

Images