Stent graft and preparation method thereof

Abstract

The present invention discloses a coated stent and a preparation method thereof, which relate to the technical field of medical devices. The coated stent includes a stent body, and the radial support strength of the middle section of the stent body is greater than the radial support strength of the two end sections of the stent body. The method for preparing the coated stent includes the following steps: obtaining the stent body, and making the radial support strength of the middle section of the stent body greater than the radial support strength of the two end sections of the stent body. The coated stent and the preparation method thereof provided by the present invention can not only provide high radial support force for stenosis, but also prevent the support force of normal blood vessel segments from being too large to stimulate the blood vessel wall or difficult to adhere to the normal blood vessel wall, thereby preventing damage to the normal blood vessel segments. The present invention can improve the treatment effect and reduce complications.

Description

Technical Field

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

[0002] A stent graft is a medical device used to treat conditions such as vascular or lumen stenosis and aneurysms. Vascular stenosis is a common cardiovascular disease, and balloon-expandable stent grafts are an important treatment for this condition. Existing balloon-expandable stent grafts are typically manufactured using a single material processing method, and all stent units on the entire balloon-expandable stent graft adopt the same structure, resulting in identical radial support at all locations throughout the balloon-expandable stent graft. This presents the following problems:

[0003] First, the radial support force distribution of the balloon-expandable covered stent is irrational: During application, high support force is required at the stenosis site to maintain vessel patency, but excessive support force in the normal vessel segment may irritate the vessel wall, leading to intimal damage, dissection, or thrombosis. Traditional stents have uniform radial support force across the entire body, making it difficult to simultaneously meet the requirements of effectively supporting the stenosis site while not damaging the normal vessel segment. Second, insufficient wall adhesion: If the support force at both ends of the stent is too high, it will be difficult to conform to the natural curvature of the normal vessel, increasing the risk of vascular damage. Summary of the Invention

[0004] The purpose of the present invention is to provide a coated stent and a preparation method thereof to solve the problems existing in the above-mentioned prior art. It can not only provide high radial support force for the stenotic area, but also prevent the support force of the normal blood vessel segment from being too large to stimulate the blood vessel wall or make it difficult to adhere to the normal blood vessel wall, thereby preventing damage to the normal blood vessel segment. The present invention can improve the treatment effect and reduce complications.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a coated stent, comprising a stent body, wherein the radial supporting strength of a middle section of the stent body is greater than the radial supporting strength of both end sections of the stent body.

[0007] 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 stent wall thickness of the middle section of the stent body is greater than the stent wall thickness of the end sections of the stent body.

[0008] Preferably, the middle section of the bracket body includes at least two closed annular brackets connected in sequence, and the two end sections of the bracket body each include at least two open annular brackets arranged in sequence; the two end sections of the bracket body are non-annealed brackets, and the middle section of the bracket body is an annealed bracket.

[0009] Preferably, at least one connecting rod is provided between two adjacent closed annular supports.

[0010] Preferably, there is an angle between the connecting rod and the axis of the bracket body.

[0011] Preferably, each of the open annular brackets includes a plurality of bracket units, each of the bracket units is a U-shaped unit or a V-shaped unit, and the plurality of bracket units are connected end to end in sequence to form an annular bracket.

[0012] Preferably, 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.

[0013] The present invention also provides a method for preparing a coated stent, comprising the following steps: obtaining a stent body, and making the radial support strength of the middle section of the stent body greater than the radial support strength of the two end sections of the stent body.

[0014] Preferably, the method further 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.

[0015] Preferably, the method for obtaining the middle section of the bracket body and the two end sections of the bracket body includes: laser cutting or etching the metal tube to process at least two open annular brackets at the two end sections of the metal tube and at least two closed annular brackets at the middle section of the metal tube.

[0016] Compared with the prior art, the present invention has achieved the following technical effects:

[0017] The present invention provides a coated stent and a preparation method thereof, comprising a stent body, wherein the radial support strength of the middle section of the stent body is greater than the radial support strength of the two end sections of the stent body, so that the middle section of the stent can provide high radial support force, and the two end sections can provide 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. The present invention optimizes the radial support strength of the stent body, which can not only provide 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 make it difficult to adhere to 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A schematic diagram of the three-dimensional structure of the first type of stent graft provided in the first form in Example 1;

[0020] Figure 2 A schematic diagram of the three-dimensional structure of the first stent graft provided in Example 1;

[0021] Figure 3 A schematic front view of the second form of the first stent graft provided in Example 1;

[0022] Figure 4 A schematic diagram of an open annular stent with a U-shaped wave provided in Example 1;

[0023] Figure 5 A schematic diagram of an open annular stent with V-shaped waves provided in Example 2;

[0024] Figure 6 Schematic diagram of the structure of the middle section of the first form of the bracket body provided in Example 1 Figure 1 ;

[0025] Figure 7 Schematic diagram of the structure of the middle section of the first form of the bracket body provided in Example 1 Figure 2 ;

[0026] Figure 8 Schematic diagram of the structure of the middle section of the second form of the bracket body provided in Example 1 Figure 1 ;

[0027] Figure 9 Schematic diagram of the structure of the middle section of the second form of the bracket body provided in Example 1 Figure 2 ;

[0028] Figure 10 A schematic structural diagram of the second stent graft provided in Example 4;

[0029] Figure 11 A schematic structural diagram of the tubular coating provided in Example 4;

[0030] Figure 12 A schematic structural diagram of the stent body in the first load diameter state and the gripping state provided in Example 4;

[0031] Figure 13 Schematic diagram of the supporting monomer structure of the stent body in the first load diameter state and the second load diameter state provided in Example 4;

[0032] Figure 14 Providing an OCT image view of the stent graft under load after implantation in a blood vessel for Example 4;

[0033] Figure 15 Schematic diagram of the microscopic morphology of the oriented filamentous structure of the tubular coating Figure 1 ;

[0034] Figure 16 Schematic diagram of the microscopic morphology of the oriented filamentous structure of the tubular coating Figure 2 ;

[0035] Figure 17 Schematic diagram of the microscopic morphology of the non-oriented arranged filamentous structure of the tubular film;

[0036] Figure 18 The coated tube body of the stent graft is relatively flat in the first load diameter state;

[0037] Figure 19 A schematic structural diagram of the balloon-expandable covered stent system provided in Example 5;

[0038] Figure 20 A partial schematic diagram of a balloon-expandable covered stent system configured to have prestress;

[0039] Figure 21 for Figure 20 Schematic diagram of the fold structure of the stent graft system in the undeployed state;

[0040] Figure 22 for Figure 20 Schematic diagram of the herringbone fold structure of the stent graft system in the undeployed state;

[0041] Figure 23 A partial diagram of the balloon-expandable covered stent system in the undeployed state, where the balloon forms a pillow structure with two opposing ends facing each other in the middle. Figure 1 ;

[0042] Figure 24 A partial diagram of the balloon-expandable covered stent system in the undeployed state, where the balloon forms a pillow structure with two opposing ends facing each other in the middle. Figure 2 ;

[0043] Figure 25 A schematic structural diagram of a balloon-expandable covered stent delivery system provided in Example 5;

[0044] Figure 26 Animal experimental images of the stent graft provided in Example 4 Figure 1 ;

[0045] Figure 27 Animal experimental images of the stent graft provided in Example 4 Figure 2 ;

[0046] Figure 28 for Figure 27In animal experiments, images of commercially available products as the control group Figure 1 ;

[0047] Figure 29 for Figure 27 In animal experiments, images of commercially available products as the control group Figure 2 ;

[0048] Figure 30 This is a clinical image of the stent graft provided in Example 4;

[0049] In the figure: 1000, the first type of coated stent; 1100, the stent body; 1010, the non-annealed stent; 1020, the annealed stent; 1030, the closed annular stent; 1040, the open annular stent; 1050, the connecting rod; 1060, the stent unit; 1200, the coated body;

[0050] 100. Second type of stent graft; 1. Tubular graft; 101. Inner graft layer; 102. Outer graft layer; 103. Distal end of stent graft; 110. First loaded diameter state; 120. Loaded state; 130. Crush state; 140. Second loaded diameter state; 111. Relatively flat tubular graft surface; 1300. Prestressed pleated structure; 1301. Pleated structure; 1302. Herringbone pleated structure;

[0051] 2. Bracket body; 200, annular bracket; 210, first annular bracket; 220, second annular bracket; 230, third annular bracket; 240, fourth annular bracket; 201, first load diameter support unit; 202, grip state support unit; 203, second load diameter support unit; 2101, first support unit of the first annular bracket; 2201, first support unit of the second annular bracket; 2202, second support unit of the second annular bracket;

[0052] 3. Elastic sleeve; 301. Distal end of elastic sleeve; 302. Proximal end of elastic sleeve;

[0053] 4. Balloon; 401. Distal end of balloon; 402. Proximal end of balloon; 403. Inner wall of balloon; 404. Outer wall of balloon; 410. Distal end of balloon catheter; 420. Balloon catheter body; 430. Proximal end of balloon catheter;

[0054] 5. Pillow structure. DETAILED DESCRIPTION

[0055] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0056] It should be noted that, in the description of the present invention, terms such as "upper," "lower," "left," "right," "inner," "outer," "front," "back," "center," "longitudinal," "lateral," "length," "width," "thickness," "vertical," "horizontal," "top," "bottom," "clockwise," and "counterclockwise" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. These are merely for ease of description and are not intended to indicate or imply that the device or component described must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "disposed," "connected," and "connected" should be understood broadly. For example, they can mean fixed, detachable, or integral; mechanical or electrical; direct or indirect through an intermediary; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0057] The purpose 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, provide moderate support for blood vessels, and effectively improve the problems of lumen restenosis and stent collapse after implantation of the existing covered stent.

[0058] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0059] Example 1

[0060] like Figures 1 to 9As shown, this embodiment provides a first coated stent 1000, including a stent body 1100, wherein the radial support strength of the middle section of the stent body 1100 is greater than the radial support strength of the two end sections of the stent body 1100, so that the middle section of the stent can provide high radial support force, and the two end sections can provide low radial support force, the middle section is used to support the stenosis, and the two end sections are used to support the normal blood vessel segments. This embodiment optimizes the radial support strength of the stent body 1100, so that the first coated stent 1000 can provide high radial support force for the stenosis, and can prevent the support force of the normal blood vessel segment from being too large and irritating the blood vessel wall or difficult to adhere to the normal blood vessel wall, thereby preventing damage to the normal blood vessel segment, improving the treatment effect and reducing complications. The middle section of the first coated stent 1000 can be one of the closed annular stent 1030 and the open annular stent 1040, or a combination thereof.

[0061] It should be noted that the middle section in this embodiment does not represent a strict geometric center, and the actual position of the middle section may be biased towards one end of the first coated stent 1000.

[0062] 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 the two end sections of the stent body 1100 are both annealed stents 1020; the stent wall thickness of the middle section of the stent body 1100 is greater than the stent wall thickness of the two end sections of the stent body 1100. The two end sections of the stent body 1100 are annealed, which can optimize the crystal structure, reduce internal defects, maintain elasticity / high ductility, and avoid damage to normal blood vessels; the middle section of the stent body 1100 is not annealed, maintaining high strength / relatively high radial support force, and avoiding collapse and loss of lumen in diseased blood vessels. This embodiment achieves a distribution optimization of the middle section providing high radial support force and the two end sections providing low radial support force through the differentiated design of not annealing the middle section and annealing the two end sections. 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 pressure applied to the blood vessel) to adapt to the different requirements of the blood vessel for radial support force along the axial / blood vessel length direction.

[0063] In some specific embodiments, such as Figure 2As shown, the middle section of the stent body 1100 includes at least two closed annular stents 1030 connected in sequence, and each end section of the stent body 1100 includes at least two open annular stents 1040 arranged in sequence. The end sections of the stent body 1100 are non-annealed stents 1010, and the middle section of the stent body 1100 is annealed stents 1020. The middle section adopts a closed-loop structure, which can provide stable radial support. The end sections of the stent body 1100 adopt open-loop structures. The open-loop structure is inherently flexible, and the combination of annealed and non-annealed stents can reduce the radial support capacity of the end sections of the stent body 1100.

[0064] Specifically, the middle section of the stent body 1100 includes a plurality of annealed closed annular stents 1030 arranged in sequence along the length direction of the first coated stent 1000, and the two end sections of the stent body 1100 include a plurality of non-annealed open annular stents 1040 arranged in sequence along the length direction of the first coated stent 1000.

[0065] In some specific embodiments, at least one connecting rod 1050 is provided between two adjacent closed annular stents 1030 . The connecting rod 1050 can further enhance the supporting capacity of the middle section of the stent body 1100 , thereby ensuring high radial support for the stenotic area.

[0066] In some embodiments, the connecting rod 1050 is angled with the axis of the stent body 1100. The connecting rod 1050 is tilted relative to the axial direction of the stent body 1100 to increase the travel of the connecting rod 1050, thereby reducing the rigidity during crimping and improving the crimping effect.

[0067] In some specific embodiments, the length direction of the connecting rod 1050 is parallel to the axis of the bracket body 1100 .

[0068] In some embodiments, each open annular stent 1040 includes multiple stent units 1060. Each stent unit 1060 is a U-shaped unit. Multiple stent units 1060 are connected end to end to form a ring-shaped stent. The openings of two adjacent U-shaped units face opposite directions, with the openings of the U-shaped units facing the ends of the stent body 1100.

[0069] In some specific embodiments, the middle section of the stent body 1100 is made of cobalt-chromium alloy, and both end sections of the stent body 1100 are made of cobalt-chromium alloy.

[0070] In some embodiments, a coating body 1200 is further included, with one end segment of the stent body 1100, the middle segment of the stent body 1100, and the other end segment of the stent body 1100 sequentially connected to the coating body 1200. The coating body 1200 may also include an oriented filamentary structure. The coating body 1200 may also include a prestressed pleated structure 1300 when not deployed.

[0071] In some specific embodiments, the membrane body 1200 is an expanded polytetrafluoroethylene (ePTFE) membrane.

[0072] In some specific embodiments, one end segment of the stent body 1100 , the middle segment of the stent body 1100 , and the other end segment of the stent body 1100 are fixed to the coating body 1200 by laser welding or by adhesive.

[0073] In some specific embodiments, the closed annular support 1030 includes a plurality of diamond-shaped units sequentially connected in a ring shape, with the diamond-shaped units of two adjacent closed annular supports 1030 being staggered. Multiple connecting rods 1050 are provided between two adjacent closed annular supports 1030, with one end of each connecting rod 1050 fixedly connected to a diamond-shaped unit of one closed annular support 1030, and the other end of each connecting rod 1050 fixedly connected to an adjacent diamond-shaped unit of an adjacent closed annular support 1030.

[0074] In some specific embodiments, the connecting rod 1050 is smoothly connected to the diamond-shaped unit connected thereto to ensure the overall flexibility of the stent body 1100.

[0075] 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.

[0076] In some specific embodiments, the radial support force of the middle section of the first coated stent 1000 is ≥1.5 N / mm, and the radial support force of the two end sections of the first coated stent 1000 is ≤0.8 N / mm.

[0077] In some embodiments, at least one end of the stent body 1100 of the first stent graft 1000 is provided with an end stent, so that the first stent graft 1000 exhibits hybrid radial support along its length. The vascular cavity environment in which the first stent graft 1000 resides (e.g., the common iliac artery and the internal iliac artery) often experiences high blood flow velocities and high pulse intensity. Under the combined effects of fluid dynamics, the first stent graft 1000 is susceptible to post-implantation displacement and poor wall adhesion. Therefore, the radial support performance of the first stent graft 1000 is optimized along its length to achieve hybrid radial support. For example, the first stent graft 1000 is arranged along its length in a sequence of high radial support segments, low radial support segments, and high radial support segments. In another example, the first stent graft 1000 is arranged along its length in a sequence of high ductility regions, high strength regions, high ductility regions, and high strength regions, or high strength regions, high ductility regions, high ductility regions, and high strength regions. The radial support performance of the first stent graft 1000 is not limited to the above-mentioned form. The radial support performance of the first stent graft 1000 can be set according to the location and number of vascular lesions to form different combinations of mixed radial support performance. It should be noted that the strong radial support performance stent segment and high strength region of the first stent graft 1000 are used to support the diseased blood vessels, while the weak radial support performance stent segment and high ductility region of the first stent graft 1000 are used to support normal blood vessels. There are at least three technical routes to achieve the above-mentioned effect: the first technical route is to anneal the stent units 1060 at both ends of the stent graft (maintaining elasticity / high ductility to avoid damage to normal blood vessels) under the same / unchanged morphological structure of the same stent unit (for example, both open or both closed), and the stent units 1060 in the middle portion are not annealed (maintaining high strength / relatively high radial support force to avoid collapse and loss of lumen in the diseased blood vessels); the second technical route is to anneal the same stent unit morphological structure by changing the stent unit. The wall thickness and width of element 1060 make the radial support force / radial support performance between each stent unit 1060 differentiated; the third technical route is hybrid optimization, which includes morphological structure differentiation between the stent units 1060, metal crystal differentiation between the stent units 1060 (that is, a combination of annealing and non-annealing treatment) and morphological structure geometric dimensions differentiation between the stent units 1060 (for example, increasing the wall thickness or reducing the wall thickness); thereby achieving hybrid radial support performance of the coated stent along its length direction (in other words, achieving hybrid radial support force values ​​of the coated stent along its length direction).

[0078] It should be noted that the typical annealing method involves heating the cobalt-chromium alloy to 800-1000°C under an inert atmosphere for 1-2 hours, followed by slow cooling to eliminate processing stress, promote dislocation movement and repair crystal defects, and form a uniform annealed microstructure while maintaining high ductility. Non-annealing, on the other hand, involves directly cold working the cobalt-chromium alloy to preserve the work-hardening effect and maintain a high dislocation density and crystal defects.

[0079] Stent unit design in the middle section of the covered stent: Compared with the open structure, the use of closed stent units (such as continuous annular support units) can provide stable radial support and enhance the ability of the middle section to resist vascular stenosis.

[0080] Stent unit design at both end sections of the covered stent: Compared with the closed type, the use of open type (such as V-shaped or U-shaped support units) can reduce the radial support force at both ends, making it easier to fit the normal blood vessel wall.

[0081] For the bracket units 1060 of the same structural form (all closed or all open), their geometric dimensions directly affect the radial support force value of the bracket unit 1060; further increasing the value relative to the original size value can improve the radial support force value of the bracket unit 1060.

[0082] Example 2

[0083] like Figures 1 to 9 As shown, this embodiment provides a first stent graft 1000. Each open annular stent 1040 of this embodiment includes multiple stent units 1060. Each stent unit 1060 is a V-shaped unit. Multiple stent units 1060 are connected end to end to form an annular stent. The openings of two adjacent V-shaped units face opposite directions, with the openings of the V-shaped units facing the ends of the stent body 1100.

[0084] The other structures, connection relationships and working principles of the first coated stent 1000 provided in this embodiment are the same as those in Example 1.

[0085] Example 3

[0086] This embodiment provides a method for preparing a coated stent, comprising the following steps: obtaining a stent body 1100 , and ensuring that the radial support strength of the middle section of the stent body 1100 is greater than the radial support strength of the two end sections of the stent body 1100 .

[0087] In some specific embodiments, it also includes: obtaining the middle section of the bracket body 1100 and the two end sections of the bracket body 1100 respectively, so that the annular brackets of the bracket body 1100 are all closed annular brackets 1030, and annealing the two end sections of the bracket body 1100.

[0088] In some specific embodiments, the method for obtaining the middle section of the bracket body 1100 and the two end sections of the bracket body 1100 includes: laser cutting or etching the metal tube, which is preferably a cobalt-chromium alloy tube, to process at least two open annular brackets 1040 at the two end sections of the metal tube and at least two closed annular brackets 1030 at the middle section of the metal tube.

[0089] In some specific embodiments, the method of annealing the two end segments of the bracket body 1100 includes: heating the two end segments of the bracket body 1100 to 800℃-1000℃ under the protection of inert gas, and keeping them warm for 1-2 hours, and then slowly cooling them. By controlling the heating temperature and heating time, it is ensured that the processing stress of the middle segment can be eliminated, dislocation movement and crystal defect repair can be promoted, and a uniform annealed structure can be formed.

[0090] In some specific embodiments, the method further includes: cutting the expanded polytetrafluoroethylene (ePTFE) membrane into a suitable size, covering the expanded polytetrafluoroethylene membrane on the surface of the stent by heat shrinking or bonding, and focusing on strengthening the fixation of the expanded polytetrafluoroethylene membrane in the middle section.

[0091] In some specific embodiments, the method further includes: cutting the expanded polytetrafluoroethylene (ePTFE) membrane into a tubular shape, putting the tubular membrane on the surface of the stent body 1100, using a heat shrink device to heat shrink and fix the tubular membrane and the stent body 1100 at 200°C-250°C, and adding an adhesive to the middle section to enhance the adhesion between the middle section of the stent body 1100 and the tubular membrane.

[0092] In some specific embodiments, after the stent body 1100 and the coating body 1200 are assembled, the first coating stent 1000 is subjected to a performance test to ensure that the distribution of the radial support force of the first coating stent 1000 meets the design requirements.

[0093] In some specific embodiments, a laser cutting machine is used to carve out the continuous annular support unit in the middle section and the bracket units 1060 at both ends on the tube.

[0094] In some specific embodiments, the method of annealing the middle section of the bracket body 1100 includes: placing the two end sections in a vacuum annealing furnace, introducing argon gas for protection, heating the annealing furnace to 900°C, keeping the temperature for 1.5 hours, and then cooling to room temperature with the furnace.

[0095] In some specific embodiments, a radial support force tester is used to measure the radial support force of the middle section and both end sections of the first coated stent 1000 to ensure that the radial support force of the middle section is ≥1.5N / mm and the radial support force of the both end sections is ≤0.8N / mm.

[0096] In some specific embodiments, the wall adhesion and flexibility of the first stent graft 1000 are verified through in vitro simulated vascular dilation experiments.

[0097] Example 4

[0098] like Figures 10 to 30 As shown, this embodiment provides a second type of coated stent 100, comprising a stent body 2 connected by a tubular coating 1, the second type of coated stent 100 having a non-load state with zero compression diameter (in the non-load state, the supporting monomer of the annular stent 200 is usually diamond-shaped), and a loaded state 120 with a compression rate relative to the non-load state for supporting the blood vessel to restore blood flow; when the compression rate of the second type of coated stent 100 is 10%, the numerical range of the radial support force of the second type of coated stent 100 is 2.0N / mm-6.0N / mm. By setting the radial support force of the second type of coated stent 100 with a compression rate of 10% to 2.0N / mm-6.0N / mm, when the second type of coated stent 100 is placed in the blood vessel lumen in the loaded state 120 to support the blood vessel, it can provide moderate support for the blood vessel, and can effectively improve the problems of lumen restenosis and stent collapse after implantation of the existing second type of coated stent 100; as shown Figures 26 to 29 As shown, the animal implantation experiment verified that the second stent graft 100 had excellent support performance compared with the common balloon-expandable stent graft on the market; after 90 days of implantation, the second stent graft 100 did not collapse (see Figure 27 , 90 days after surgery, DSA and OCT images showed that the second type of covered stent 100 as a whole and at the point indicated by the arrow maintained a relatively complete stent lumen, with a low lumen loss rate and a vascular stenosis rate of approximately 8.6%). The control group of the commercially available product showed obvious vascular stenosis and stent collapse (see Figure 29 , DSA and OCT images 90 days after surgery, the control group of commercially available products showed collapse as a whole and at the point indicated by the arrow, with a high lumen loss rate and a vascular stenosis rate of approximately 17.4%).

[0099] It should be noted that the zero-compression diameter refers to the natural diameter of the second-type covered stent 100 when fully released (not subjected to external compression or extension). The radial support force of the second-type covered stent 100 must be tested in accordance with "YY / T 1660-2019 Radial Load Test Method for Balloon-Expandable and Self-Expanding Stents," meaning the radial support force of the second-type covered stent 100 must be tested at a compression ratio of 10%. The second-type covered stent 100 features a bridgeless design, offering excellent compliance. The support unit utilizes a diamond-shaped ring design, which, through simulation, has been shown to exhibit high radial strength, fatigue resistance, and post-expansion performance. This structural unit exhibits excellent anti-collapse properties in practical applications, improving vascular patency. Animal studies comparing the second-type covered stent 100 to existing marketed products have demonstrated that the second-type covered stent 100 exhibits improved vascular patency and stent collapse resistance.

[0100] 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 stenosis site). After being implanted in the blood vessel, the second covered stent 100 is released and contacts the normal blood vessel and is compressed. After being released, the second covered stent 100 supports the blood vessel at the stenosis site under the expansion action of the balloon 4, so that the diameter of the blood vessel at the stenosis site is approximately the same or the same as that of the normal blood vessel. The compression rate of the second covered stent 100 when placed in the blood vessel for support is approximately 10%.

[0101] As a preferred embodiment, when the compression rate of the second stent graft 100 is 10%, the radial support force of the second stent graft 100 has a numerical range of 3.0 N / mm-4.5 N / mm.

[0102] In some specific embodiments, at the initial moment when the second stent graft 100 is deployed in the vascular lumen in the loaded state 120, the cross-sectional area of ​​the hollow lumen of the second stent graft 100 is the immediate cross-sectional area; when the second stent graft 100 is deployed in the vascular lumen and maintained for 90 days, the cross-sectional area of ​​the hollow lumen of the second stent graft 100 is the first cross-sectional area, and the ratio of the average first cross-sectional area of ​​the second stent graft 100 to the average immediate cross-sectional area of ​​the second stent graft 100 is greater than 0.7, that is, this embodiment significantly improves the problems of lumen restenosis and stent loss after implantation of the second stent graft 100. Furthermore, when the stent graft is deployed in the vascular lumen and maintained for 90 days, the ratio of the average first cross-sectional area of ​​the stent graft to the average immediate cross-sectional area of ​​the stent graft is greater than 0.85.

[0103] In some 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 material can improve the support performance of the stent body 2 and improve the problem of stent body 2 collapsing.

[0104] As a preferred embodiment, the material of the bracket body 2 is MP35N nickel-cobalt alloy.

[0105] In some specific embodiments, the stent body 2 includes a plurality of annular stents 200 spaced apart longitudinally along the tubular coating 1; the tubular coating 1 has a microscopic morphology of a filamentous structure arranged in an orientation, and the force on at least part of the annular stents 200 can be transmitted to the adjacent annular stents 200 through the filamentous structure of the tubular coating 1. The filamentous structure can transmit stress along the longitudinal direction of the second-type coated 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-type coated stent 100 and improving the problem of stent collapse. Furthermore, the filamentous structure arranged in an orientation helps / cooperates with the second-type coated stent 100 to form a prestressed pleated structure 1300 during the process of squeezing and tightening the delivery system, thereby improving the problem of longitudinal length shortening of the second-type coated stent 100 that occurs during the delivery and release of the second-type coated stent 100.

[0106] In some specific embodiments, the tubular coating 1 includes at least an inner coating layer 101 and an outer coating layer 102, and the stent body 2 is fixedly connected between the inner coating layer 101 and the outer coating layer 102; the inner coating layer 101 and the outer coating layer 102 have different microscopic morphologies. This configuration promotes the mechanical anisotropy of the tubular coating 1, which can not only take into account the bending performance of the second type of coated stent 100, but also improve the force dispersion performance of the local coating of the second type of coated stent 100 after being pressurized by the blood vessel, so that it maintains its original shape after being implanted in the blood vessel (such as Figure 26 The circular lumen of OCT immediately after surgery, Figure 27 90 days after surgery, OCT showed a circular lumen with little or no change), avoiding lumen collapse (e.g. Figure 28 The circular lumen of OCT immediately after surgery, Figure 29 90 days after surgery, the OCT image collapsed into an irregular cavity with a non-circular lumen), maintaining the initial lumen rate.

[0107] In some specific embodiments, the inner coating layer 101 has an oriented filamentous microstructure; the outer coating layer 102 has a filamentous microstructure, with the filaments of the outer coating layer 102 being shorter than those of the inner coating layer 101. The filamentous structure can increase the surface roughness of the outer coating layer 102. The rough outer wall of the outer coating layer 102 contacts the blood vessel wall and provides support for the vessel, thereby enhancing the anchoring of the outer coating layer 102 to the blood vessel intima and preventing displacement of the second type of covered stent 100 after implantation.

[0108] In some specific embodiments, the outer coating layer 102 has a non-oriented filamentous structure microstructure.

[0109] In some embodiments, the stent body 2 includes a plurality of annular stents 200 spaced longitudinally along the tubular covering 1. The filamentous structure of the tubular covering 1 between adjacent annular stents 200 extends longitudinally along the tubular covering 1. The filamentous structure of the tubular covering 1 enhances the longitudinal support strength between the annular stents 200, thereby reducing the likelihood of longitudinal shortening of the second stent graft 100 due to interaction with the balloon-expandable stent graft system during its release.

[0110] In some specific embodiments, at least two ends of the filamentary structure of a portion of the tubular coating 1 are respectively connected to two annular stents 200 . Specifically, the two ends of the filamentary structure are connected to two adjacent annular stents 200 through the coating.

[0111] In some specific embodiments, multiple filamentous structures of the coated tube body between two annular stents 200 are arranged along the circumference of the second coated stent 100, that is, multiple filamentous structures are provided between two adjacent annular stents 200 to improve the supporting effect.

[0112] In some specific embodiments, each annular stent 200 is cut from an alloy tube; each annular stent 200 has a first load diameter that is sleeved on the outer surface of a filled balloon to expand to a diameter greater than 10% of the blood vessel diameter; when each annular stent 200 is in the first load diameter state 110, the second coated stent 100 has a first load state; the second coated stent 100 has a transport state that is sleeved on the outer surface of a non-filled balloon; the ratio of the longitudinal length value of the second coated stent 100 in the first load state (expanded state / expanded state) to the longitudinal length value of the second coated stent 100 in the transport state (gripped state 130 / undeployed state) is greater than 0.95; when the second coated stent 100 is in the first load state, part of the tubular coating 1 is supported by the annular stent 200 without elastic deformation (such as Figure 18 As shown, a relatively flat tubular coating surface 111 is presented in the rhombus region of the support monomer of the first load diameter. When the annular stent 200 is expanded at the stenosis site, it usually covers the normal blood vessels near the stenosis lesion. The blood vessels at the stenosis site and the normal site are subjected to different vascular reaction forces. There are multiple annular stents 200 on the entire stent. Some of the annular stents 200 may be expanded too much, causing elastic deformation of the coating. The second coated stent 100 is transported in a gripping state 130. By reasonably setting the longitudinal length of the second coated stent 100 in the transport state, and enabling the annular stent 200 to support the tubular coating 1 and prevent at least part of the tubular coating 1 from elastic deformation when the second coated stent 100 is released, the problem of shortening of the longitudinal length of the second coated stent 100 caused by the interaction with the balloon expansion coated stent system during the release of the second coated stent 100 is improved.

[0113] In some specific embodiments, each annular stent 200 further has a second load diameter that is larger than the diameter of the alloy tube; the portion of the tubular coating 1 can be stretched and elastically deformed by the annular stent 200 in the second load diameter state 140. When the balloon 4 is expanded, the annular stent 200 can be expanded to reach the second load diameter. Figure 13 As shown, generally, the circumferential length L of the first load diameter supporting unit 201 of the first load diameter state 110 is smaller than the circumferential length L of the second load diameter supporting unit 203 of the second load diameter state 140 .

[0114] In some specific embodiments, such as Figure 12 and Figure 13 Each annular bracket 200 includes a plurality of frames (a first load diameter support unit 201, a gripping state support unit 202, and a second load diameter support unit 203) arranged circumferentially around the tubular coating 1 and connected by connecting rods. The frame includes a seam with a changeable shape surrounded by a continuous metal boundary; the coating between the two annular brackets 200 has a circumferentially continuous tubular body.

[0115] The peripherally expanded balloon-grafted stent system typically consists of the second type of covered stent 100 and a delivery system, with the stent pre-installed on the delivery system's balloon 4. The stent is composed of a balloon-expandable cobalt-based alloy stent ring and a fluoropolymer. The delivery system consists of a distal tip, a contrast ring, an inner tube, a balloon 4, a catheter, a catheter reinforcement, and a catheter hub. Two contrast rings are located inside the balloon 4 and near each end of the stent, indicating the effective length of the balloon 4 and facilitating stent placement. The delivery system is compatible with a 0.035-inch (0.89 mm) guidewire and can be used for both initial stent placement and post-stent expansion. Pre-installed stent systems are available in a variety of stent diameters and lengths. Pre-installed delivery system catheters are available in 75 cm and 135 cm lengths. The peripherally expanded balloon-grafted stent system is used to treat stenotic and / or occlusive lesions of the common and external iliac arteries.

[0116] Examples of clinical uses of covered stents (e.g. Figure 30 shown):

[0117] 1) Vascular treatment

[0118] 1. Establish vascular access

[0119] a) After appropriate local anesthesia, select a suitable vascular access technique. If possible, a percutaneous Seldinger puncture technique is preferred. A superficial cutaneous incision may be performed if necessary.

[0120] b) Using standard techniques, insert an appropriately sized vascular sheath into the vessel.

[0121] 2. Imaging and Measurement

[0122] Angiography assesses and marks the location of lesions or stenosis segments under X-rays to observe the location of vascular stenosis or occlusion. The diameter and length of the target lesion are measured to determine the required stent specifications. If necessary, a measuring guidewire or catheter is used for measurement.

[0123] 3. Percutaneous transluminal angioplasty (PTA)

[0124] a) Pre-dilation of the lesion is recommended to facilitate the passage of the stent system.

[0125] b) Inflate the angioplasty balloon 4 to the nominal pressure. Ensure that the balloon 4 is fully expanded within the lesion. Note: Carefully mark the boundaries of the angioplasty treatment segment to ensure complete stent coverage.

[0126] c) After balloon 4 is deflated, angiography is used to evaluate the results. The vessel diameter, lesion length, and residual stenosis percentage are measured for reference.

[0127] 4. Stent Sizing and Selection

[0128] Before opening the sterile packaging and removing the contents, check that the diameter and length of the stent and the effective length of the delivery system are correct.

[0129] ● Careful assessment of the vessel is necessary to select the appropriate size stent.

[0130] Stenotic or obstructive lesions: To minimize the possibility of vascular damage, the outer diameter of the stent should be approximately 10% larger than the vessel diameter proximal and distal to the stenosis. To prevent stent migration, ensure that the device is in close contact with the vessel wall during initial deployment and post-implantation expansion.

[0131] ● Verify that the delivery system catheter is of sufficient length to reach the treatment site.

[0132] 2) Stent Preparation

[0133] 1. Carefully inspect the packaging for damage. Do not use if the expiration date has expired. Open the box and remove the sterile inner bag containing the stent. Starting from one corner, tear open the edge of the inner bag and gently remove the stent system.

[0134] 2. Check before use:

[0135] ● Before using this product, carefully inspect all materials and equipment used in the procedure for bends, kinks, or other damage.

[0136] ● Do not use any damaged or defective equipment or materials.

[0137] ● Do not use the product if the sterile packaging is damaged or the stent system is damaged.

[0138] 3. Before placing the catheter over the guidewire, the distal end of the stent system can be bent into a round shape to make the delivery system easier to track. During the bending process, care should be taken to ensure that the metal stent ring is not deformed, dislocated, or damaged.

[0139] 4. Preparation of the stent delivery system catheter:

[0140] a) Connect a syringe of heparinized saline to the guidewire port of the stent system and flush the delivery catheter until a steady stream of water is emitted from the catheter tip.

[0141] b) After flushing the catheter, remove the syringe.

[0142] c) Prepare the charging device / syringe with diluted contrast medium (a 1:1 mixture of contrast medium and saline), or any other medium deemed appropriate by the physician.

[0143] d) Connect the inflation device / syringe to the T-connector (if necessary) and then to the inflation port of the stent system.

[0144] e) Open the three-way connector leading to the stent system. With the distal balloon tip facing downward, lower than the level of the inflation device / syringe, pull the plunger of the inflation device / syringe to create negative pressure and maintain it for 20-30 seconds. Carefully release the plunger until there is no pressure to inflate the contrast agent. Do not apply positive pressure at this time, as this may cause partial deployment of the stent.

[0145] f) Close the T-connector to the support system; purge all air from the inflation device / syringe.

[0146] g) Repeat steps e) and f) until all air is removed. If air bubbles remain, do not use the bracket system.

[0147] h) Connect the prepared charging device / syringe to the T-connector and open the T-connector.

[0148] 5. Once the bracket surface has been moistened, do not allow it to dry out.

[0149] 3) Introduction and positioning of the stent

[0150] 1. Select a vascular sheath of appropriate size and free of kinks. It is recommended to use a sheath long enough to pass through the lesion. Using a vascular sheath can minimize the risk of the stent being dislodged from the balloon during tracking. Use standard interventional techniques to introduce the stent into the target lesion.

[0151] 2. Ensure the guidewire diameter is 0.035" (0.89mm).

[0152] 3. Ensure that the guidewire remains positioned beyond the target lesion while the balloon catheter is removed until the procedure is complete to avoid reintroduction.

[0153] 4. Insert the tail end of the guidewire into the head end of the stent system, keeping the tube as straight as possible. Carefully advance the stent slowly (approximately 0.5 cm at a time) along the guidewire, passing through the hemostatic valve and vascular sheath, and into the access vessel. Note: If excessive resistance is felt when guiding the stent through the hemostatic valve, remove it and inspect it for damage. Do not use the stent if it is damaged or if displacement of the stent graft relative to the imaging ring marker on the delivery system is observed under X-ray.

[0154] 5. Under X-ray guidance, carefully advance the delivery system along the guidewire. If you feel excessive resistance, remove the product and vascular sheath together.

[0155] 6. Under direct X-ray visualization, position the stent across the target lesion. Using the proximal and distal markers on the delivery system (indicating the effective length of balloon 4) and the radiopaque stent as reference points, position the stent at the lesion. Note: After stent deployment, both ends of the stent will be within the effective length of balloon 4 due to longitudinal shortening. This shortening should be factored into stent selection to ensure coverage of the intended lesion. During positioning, confirm that the stent remains centered within the marker band and has not fallen out. Do not deploy the stent unless it is centered on balloon 4 and correctly positioned within the target lesion. If the stent is within the lesion but not in the optimal position, it should be carefully repositioned or withdrawn.

[0156] If a PTA is performed, the stent should cover the entire vessel segment treated with balloon angioplasty. Where appropriate, it is recommended that the stent extend at least 1 cm beyond the proximal and distal edges of the lesion.

[0157] 7. After confirming optimal positioning under X-ray, begin deploying the stent. Note: Do not withdraw the stent into the sheath after it has been fully introduced. To withdraw the stent, withdraw it close to the sheath but not into it. The stent system and sheath can then be removed simultaneously. Once removed, it must not be reused. Do not attempt to withdraw a partially expanded or unexpanded stent system into the sheath, as this may cause the stent to dislodge from the balloon 4. Carefully observe the stent for dislodgement or movement while attempting to withdraw the unexpanded stent through the sheath.

[0158] 4) Deployment of the stent

[0159] 1. Maintain the delivery system stably at the hemostatic valve of the vascular sheath, maintain the position of the delivery system catheter and vascular sheath relative to the patient, and reduce catheter movement during deployment to ensure accurate positioning of the stent.

[0160] 2. To reduce the possibility of vascular injury, select a stent with an outer diameter approximately 10% larger than the vessel diameter proximal and distal to the stenosis. Use the inflation device to slowly inflate the stent system to the pressure required to achieve the desired diameter, maintaining inflation pressure for approximately 15 seconds. To minimize the effects of any luminal damage or stent recoil due to the lesion site, higher inflation pressures may be required, but the pressure must not exceed the rated burst pressure. Oversizing a stent relative to the vessel diameter may cause vascular injury, while undersizing may result in stent migration. The compliance chart provided on the package label is generated under idealized in vitro conditions and does not account for in vivo lesion site characteristics, vascular characteristics, and interpatient variability. Therefore, the compliance chart should be used as a general guide, and the user should confirm the stent diameter and length during balloon inflation and deployment and by angiography.

[0161] 3. After deploying the stent, use the inflation device to manually and slowly deflate the balloon 4 to ensure proper recapture of the balloon 4. Before withdrawing the stent, allow sufficient time for the balloon 4 to be completely deflated and observe the complete deflation of the balloon 4 under X-ray.

[0162] 4. Maintaining proper sheath support, very slowly withdraw balloon 4. Observe under X-ray to ensure that balloon 4 is detached from the stent. If resistance is encountered during withdrawal, do not force withdrawal. Use X-ray and conventional techniques to determine and correct the cause of the resistance before continuing.

[0163] 5. Use angiography to confirm the position and deployment of the stent. For optimal results, the stent should cover the entire lesion. X-rays are used to compare the proximal and distal ends of the stent with the reference vessel diameter to accurately determine the optimal post-expansion stent diameter.

[0164] 6. If resizing is necessary, re-advance the delivery system catheter or another balloon catheter of appropriate size to the stented area using standard interventional techniques.

[0165] 7. Under X-ray observation, inflate balloon 4 to the nominal pressure, but do not exceed the rated burst pressure. When using another balloon 4 for post-implantation dilation, select a balloon 4 that is shorter than the deployed stent length. Do not inflate balloon 4 beyond the ends of the stent and into healthy vessels, as this may cause restenosis and subsequent failure. Deflate balloon 4 and proceed as described above.

[0166] 8. Reconfirm the stent position and angiographic results. Inflate again until the desired effect is achieved.

[0167] 5) After the stent is deployed

[0168] 1. While maintaining the negative pressure within the balloon 4 and the guidewire position across the treatment lesion, carefully withdraw the delivery system from the body through the vascular sheath. You may feel some resistance when withdrawing the balloon 4 through the catheter.

[0169] Note: During catheter withdrawal, if balloon 4 becomes lodged in the leading edge of the sheath, gently moving the catheter back and forth may help dislodge it. If necessary, the delivery system and sheath can be withdrawn together. Excessive force or force during catheter withdrawal may damage the delivery catheter or sheath.

[0170] 2. A final angiogram is recommended to assess vascular patency.

[0171] 3. When clinical conditions are suitable, remove the vascular sheath and stop bleeding at the puncture site.

[0172] Example 5

[0173] like Figures 19 to 25 As shown, this embodiment provides a balloon-expandable coated stent system, comprising an elastic sleeve 3, a balloon 4, a core shaft (for example, a 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 coated stent 100 in Example 5, the second coated stent 100, the elastic sleeve 3, the balloon 4 and the core shaft are sequentially arranged from the outside to the inside; both ends of the balloon 4 are sealed and fixedly connected to the core shaft, and can be filled and expanded through the liquid channel of the core shaft; the proximal end 302 of the elastic sleeve is fixedly connected to the core shaft, or the proximal end 302 of the elastic sleeve is fixedly connected to the proximal end 402 of the balloon; the distal end 301 of the elastic sleeve is movably mounted on the balloon; the radially contracted / compressed / unexpanded second coated stent 100 can be removably mounted on the elastic sleeve 3. The elastic sleeve 3 can provide a relatively thick and concave elastic carrier for the second stent graft 100, so that the second stent graft 100 can be tightly loaded / clamped on the balloon-expandable stent graft system (delivery system), that is, the second stent graft 100 can be concave to a certain extent in the outer wall of the elastic sleeve. When the loading is completed, the second stent graft 100 will have a radial rebound of 0.1 to 0.2 mm. At this time, the concave part of the elastic sleeve 3 under the action of the second stent graft 100 can also have an appropriate rebound, so that the second stent graft 100 can be tightly loaded / clamped on the balloon-expandable stent graft system (delivery system). 00, the elastic sleeve 3 and the balloon 4 can better contact each other, ensuring that there is sufficient friction between the second coated stent 100, the elastic sleeve 3 and the balloon 4. When the second coated stent 100 is withdrawn from the delivery sheath, the lengthwise displacement and shortening of the second coated stent 100 can be reduced; when the balloon 4 expands, the second coated stent 100 is caused to expand radially. Due to the friction between the elastic sleeve and the second coated stent 100, the lengthwise displacement and shortening of the second coated stent 100 during the expansion process are reduced.

[0174] In some embodiments, the balloon-expandable stent graft system can be expanded from an undeployed state (e.g., Figure 19 ) to an expanded state having an expanded diameter (as shown Figure 25 As shown); Figure 20 As shown, in the balloon-expandable covered stent system in the undeployed state, the covered stent is constructed to have prestress, or the elastic sleeve is constructed to have prestress, or the balloon 4 is constructed to have prestress; for example, a prestressed pleated structure 1300 (including a pleated structure 1301 and a herringbone pleated structure 1302) is formed between each annular stent 200 (the first annular stent 210, the second annular stent 220, the third annular stent 230, and the fourth annular stent 240), and the prestressed pleated structure 1300 is distributed at intervals along the circumference of the second covered stent 100 and at intervals along the longitudinal direction of the second covered stent 100. Distribution; for another example, gas or liquid is pre-stored in the cavity of the end portion of the balloon 4 (near the distal end 401 or the proximal end 402 of the balloon) so that the end segment of the balloon 4 is slightly raised / convex (usually, the height of the raised / convex is level with the height level of the end portion of the second coated stent 100, or higher than the height level of the end portion of the second coated stent 100) to form a pillow structure 5 (pillow); the length between the two ends of the second coated stent 100 is smaller 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 edge of the end portion of the second coated stent 100 to form a pillow structure 5 (pillow).

[0175] In some embodiments, the prestressed design is also applied to a balloon delivery system / structure without an elastic sheath. The balloon delivery system / structure without an elastic sheath is a conventional (or commercially available) balloon catheter; that is, the stent graft on the balloon catheter has a prestressed pleated structure 1300, or the balloon 4 has a pillow structure 5.

[0176] In some specific embodiments, such as Figure 21As shown, the undeployed stent graft is distributed with a plurality of longitudinally extending folds 1301 formed by prestressing. Typically, the folds 1301 extend from one end of a ring-shaped stent strut to the gap between the struts of another ring-shaped stent; for example, the folds 1301 extend from one end of a first strut 2101 of the first ring-shaped stent 210 to the gap between the first strut 2201 and the second strut 2202 of the second ring-shaped stent 220. It will be appreciated that, like the folds in origami, the folds of the folds 1301 can enhance the longitudinal compression resistance compared to a flat graft (e.g., the relatively flat tubular graft surface 111), thereby enhancing the second type of graft 100's resistance to shortening. Typically, the dimension of a single fold 1301 near the distal end 103 of the graft is smaller than the dimension away from the distal end 103.

[0177] In some specific embodiments, during the deployment of the balloon-expandable stent graft system, the pleated structure 1301 can inhibit the longitudinal shortening of the stent graft.

[0178] In some specific embodiments, such as Figure 19 、 Figure 23 and Figure 24 As shown, the balloon 4 in the unexpanded state has a pillow structure 5. Figure 19 As shown, the end of the balloon 4 (near the distal end 401 or the proximal end 402) is pre-stored with gas or liquid in the cavity, so that the end section of the balloon 4 is slightly raised / convex to form a pillow structure 5. Figure 23 As shown, usually, when passing through the sheath channel or the vascular cavity constructed by the percutaneous Seldinger puncture technique, the pillow structure 5 of the balloon-expandable coated stent system will be squeezed and deformed by the sheath wall or the vascular 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 coated stent 100, lifting the balloon wall in this area, so that the inner wall 403 of the balloon is away from the balloon catheter body 420, and the outer wall 404 of the balloon applies a force to the inner wall of the elastic tube sleeve 3, dynamically compensating for the force between the inner wall of the second coated 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 coated stent 100 and the outer wall of the elastic tube sleeve 3), thereby suppressing the second coated stent 100 from being detached.

[0179] In some specific embodiments, such as Figure 19 As shown, in the balloon-expandable covered stent system in the undeployed state, gas or liquid is pre-stored in the cavity of the balloon 4 to form a pillow structure 5 with both ends (such as the distal end 401 or the proximal end 402 of the balloon) protruding relative to the middle.

[0180] 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 inhibit the second covered stent 100 from being detached from the balloon-expandable covered stent system.

[0181] In the embodiments of the present invention, the various listed stent grafts, annular stents, and delivery systems can be freely combined into a balloon-expandable stent graft system according to actual use. The stent graft provided by the present invention is used to treat stenosis and / or occlusion of the common iliac artery and external iliac artery.

[0182] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A stent graft, characterized in that: The stent comprises a stent body, wherein the radial support strength of the middle section of the stent body is greater than the radial support strength of the two end sections of the stent body; the stent graft is a balloon expandable stent graft; The middle section of the stent body includes at least two closed annular stents connected in sequence, and both end sections of the stent body include at least two open annular stents arranged in sequence; the both end sections of the stent body are non-annealed stents, and the middle section of the stent body is an annealed stent.

2. The stent graft according to claim 1, wherein: The wall thickness of the middle section of the bracket body is greater than the wall thickness of the two end sections of the bracket body.

3. The stent graft according to claim 1, wherein: At least one connecting rod is provided between two adjacent closed annular supports.

4. The stent graft according to claim 3, wherein: An included angle is formed between the connecting rod and the axis of the bracket body.

5. The stent graft according to claim 1, wherein: Each of the open annular brackets includes a plurality of bracket units, each of the bracket units is a U-shaped unit or a V-shaped unit, and the plurality of bracket units are connected end to end in sequence to form an annular bracket.

6. The stent graft according to claim 1, wherein: The middle section of the bracket body is made of cobalt-chromium alloy, and both end sections of the bracket body are made of cobalt-chromium alloy.

7. A method for preparing a stent graft, characterized in that: The method comprises the following steps: obtaining a stent body, and making the radial support strength of the middle section of the stent body greater than the radial support strength of the two end sections of the stent body; the stent graft is a balloon expandable stent graft; The middle section of the stent body includes at least two closed annular stents connected in sequence, and both end sections of the stent body include at least two open annular stents arranged in sequence; the both end sections of the stent body are non-annealed stents, and the middle section of the stent body is an annealed stent.

8. The method for preparing a stent graft according to claim 7, wherein: The method for obtaining the middle section and the two end sections of the bracket body includes: laser cutting or etching the metal tube to process at least two open annular brackets at the two end sections of the metal tube and at least two closed annular brackets at the middle section of the metal tube.

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