Stent graft

Abstract

The present invention relates to a stent graft. The stent graft comprises: a metal stent, an inner coating, and at least one outer coating; the inner coating is arranged on the metal stent, the outer coating is arranged on the outside of the inner coating, at least one cavity is formed between the inner coating and the at least one outer coating, and the outer coating can be expanded. The stent graft can be used in the field of treating abdominal aortic aneurysms. The inner cavity of the inner coating can ensure the normal flow of blood in the abdominal aorta, and the outer coating arranged on the outside of the inner coating can be expanded to form a close-fitting surface of the aneurysm cavity wall or an arterial blood vessel wall, which can block the branch blood vessels on the abdominal aortic aneurysm, block the backflow of blood in the branch blood vessels, prevent type II endoleak, and avoid further expansion of the abdominal aortic aneurysm. No secondary intervention is required, that is, no further surgery is required, thereby avoiding greater risks for patients.

Description

Technical Field

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

[0002] Endovascular intervention, as a minimally invasive treatment, improves the survival rate for patients with vascular diseases who cannot tolerate surgery. Covered stents, one of the key implants used in endovascular intervention, can develop type II endoleaks after endovascular aneurysm repair in patients with abdominal aortic aneurysms, causing further aneurysm expansion and posing a life-threatening risk. Currently, the mainstream treatment for type II abdominal aortic endoleaks is a secondary intervention, requiring another surgery, which places greater risks on patients. Summary of the Invention

[0003] Based on this, it is necessary to provide a covered stent to address the problem of type II endoleakage of the covered stent after endovascular aneurysm repair in patients with abdominal aneurysms.

[0004] A stent graft, comprising: a metal stent, an inner layer graft, and at least one outer layer graft;

[0005] The inner layer coating is arranged on the metal stent to form an inner cavity that passes through the metal stent axially. The outer layer coating is arranged around the outer side of the inner layer coating. At least one cavity is formed between the inner layer coating and the at least one outer layer coating. The outer layer coating can be expanded.

[0006] In one embodiment, the inner layer has a preset leakage rate, which is 300 (ml / cm 2 / min)-1000(ml / cm 2 / min).

[0007] In one embodiment, a thrombogenic agent or villi are placed in the clip cavity.

[0008] In one embodiment, the stent graft further comprises: a filler placed in the clamp cavity, wherein the filler is used to expand the outer layer of the graft.

[0009] In one embodiment, the outer coating surrounds the barrier portion of the inner coating, wherein the proximal and distal ends of the outer coating are respectively sealed and fixed to the barrier portion;

[0010] The outer coating is made of a flexible material, and the surface area of the outer coating is larger than the surface area of the barrier portion.

[0011] In one embodiment, the material of the inner layer coating and / or the outer layer coating is at least one of PET, ePTFE or Tpu.

[0012] In one embodiment, the proximal and distal ends of the outer layer coating are fixed to the outer side of the inner layer coating by sewing or hot melting.

[0013] In one embodiment, at least one visceral artery blood supply site is provided on the inner covering;

[0014] The number of the cavities is greater than or equal to 2, and the cavities are distributed sequentially from the proximal end to the distal end of the inner covering, and two adjacent cavities are separated at the distal and proximal sides of the corresponding visceral artery blood supply position.

[0015] In one embodiment, the number of the outer coatings is greater than or equal to 2, and a cavity is formed between each outer coating and the inner coating.

[0016] In one embodiment, at least one visceral artery blood supply site is provided on the inner covering;

[0017] The number of the outer covering and the number of the clamping cavity are both 1, the outer covering has at least one blood supply window and the part of the outer covering located around the blood supply window is fixed on the inner covering, and the blood supply window is connected to the corresponding visceral artery blood supply position.

[0018] In one embodiment, the stent graft includes a main stent graft and a branch stent graft connected to a distal end of the main stent graft;

[0019] The distal end of the outer coating is fixed on the inner coating of the branch coated stent.

[0020] The covered stent as described above can be used in the treatment of abdominal aortic aneurysms. The inner lumen of the inner covering can ensure the normal flow of blood in the abdominal aorta, and the outer covering surrounding the outer side of the inner covering can be expanded to form a close-fitting surface of the aneurysm cavity wall or the arterial blood vessel wall, which can block the branch blood vessels on the abdominal aortic aneurysm, block the backflow of blood in the branch blood vessels, prevent type II endoleak, and avoid further expansion of the abdominal aortic aneurysm. No secondary intervention is required, that is, no another operation is required, thereby avoiding greater risks for patients. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic structural diagram of a stent graft provided in one embodiment of the present invention;

[0022] Figure 2 A schematic diagram of the installation of a stent graft provided in one embodiment of the present invention;

[0023] Figure 3 A schematic diagram of the installation of a stent graft provided by another embodiment of the present invention;

[0024] Figure 4 A schematic diagram of the installation of a stent graft provided by another embodiment of the present invention;

[0025] Figure 5 A schematic diagram of the installation of a stent graft provided in another embodiment of the present invention.

[0026] The reference numerals in the accompanying drawings are described as follows:

[0027] 100, metal stent; 110, bare metal stent; 200, inner covering; 300, outer covering; 310, proximal outer covering; 320, distal outer covering; A, lumens; 400, branch vessels; 500, iliac artery; 500a, iliac artery bifurcation; 600, visceral artery; F1, aneurysm cavity wall-adherent surface; F2, arterial vessel wall-adherent surface. DETAILED DESCRIPTION

[0028] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0029] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0031] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0032] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0033] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0034] See Figure 1 , Figure 1 A schematic structural diagram of a coated stent in an embodiment of the present invention is shown. The coated stent provided in an embodiment of the present invention includes: a metal stent 100, an inner coating 200 and at least one outer coating 300; the inner coating 200 is arranged on the metal stent 100 to form an inner cavity that passes through the metal stent 100 axially; the outer coating 300 is arranged around the outside of the inner coating 200, and at least one sandwich cavity A is formed between the inner coating 200 and at least one outer coating 300, and the outer coating 300 can be expanded.

[0035] It should be noted that the stent graft according to the embodiment of the present invention can be used in the treatment of abdominal aortic aneurysms. The outer coating 300 can be expanded to block the branch vessels 400 on the aortic aneurysm (see Figures 2 to 5), branch vessels 400 do not refer to important visceral arteries such as the renal arteries, celiac trunk, and superior mesenteric artery. Instead, they refer to branch vessels that, even if blood flow is blocked, will not cause serious complications in the human body. Furthermore, the lumen of the inner coating 200 is used to maintain normal blood flow in the abdominal aorta.

[0036] As an example, Figures 1 to 5 As shown, the metal stent 100 is made of biocompatible metal materials such as nickel-titanium alloy and stainless steel. The metal stent 100 includes a plurality of support rings arranged at intervals; the support rings can be arranged in a circular ring shape, a wavy shape, and other structures. Optionally, as Figure 1 As shown, a bare metal stent 110 is provided on the proximal end of the metal stent 100, and the bare metal stent 110 is used to anchor the stent graft. The bare metal stent 110 can be provided in a circular ring shape, a wave shape, or other structures.

[0037] The covered stent as described above can be used in the treatment of abdominal aortic aneurysms. The inner cavity of the inner covering 200 can ensure the normal flow of blood in the abdominal aorta, and the outer covering 300 surrounding the outer side of the inner covering 200 can be expanded to form a close-fitting surface of the aneurysm cavity wall or the arterial blood vessel wall, thereby blocking the branch blood vessels 400 on the abdominal aortic aneurysm, blocking the backflow of blood in the branch blood vessels 400, preventing type II endoleak, and avoiding further expansion of the abdominal aortic aneurysm without the need for secondary intervention, that is, no need for another operation, thereby avoiding greater risks for the patient.

[0038] In some embodiments of the present invention, the outer coating 300 can form an aneurysm cavity wall-adhering surface F1 when expanded. When the outer coating 300 fills the aneurysm cavity of the abdominal aortic aneurysm, its aneurysm cavity wall-adhering surface F1 closely adheres to the inner wall of the aneurysm cavity of the abdominal aortic aneurysm. This not only covers the branch vessels 400 and blocks blood flow backflow within the branch vessels 400, but also allows the outer coating 300 to be in close contact with the proximal and distal ends of the abdominal aortic aneurysm, thereby providing a certain degree of protection against type I endoleak caused by loose adhesion between the proximal and distal ends of the stent graft and the abdominal aortic vessels. Throughout this document, the proximal end refers to the end closest to the heart, and the distal end refers to the end away from the heart.

[0039] Regarding how to expand the outer film 300, the present invention provides two examples:

[0040] (1) In some embodiments of the present invention, the inner coating 200 has a preset leakage rate, so that the blood flow in the inner coating 200 can pass through the inner coating 200 and flow into the cavity A between the outer coating 300 and the inner coating 200, thereby expanding the outer coating 300. Due to the leakage of the inner coating 200 in the short term after surgery, the blood flow in the inner coating 200 can pass through the inner coating 200 and slowly enter the cavity A between the outer coating 300 and the inner coating 200, thereby expanding the outer coating 300, thereby achieving the purpose of blocking the branch blood vessel 400.

[0041] Optionally, the preset leakage rate is 300 (ml / cm 2 / min)-1000(ml / cm 2 / min), for example, it can be set to 300 (ml / cm 2 / min)、400(ml / cm 2 / min)、500(ml / cm 2 / min)、600(ml / cm 2 / min)、700(ml / cm 2 / min)、800(ml / cm 2 / min)、900(ml / cm 2 / min)、1000(ml / cm 2 / min) and so on. Setting the preset leakage range in this way can ensure that the blood flow in the inner layer coating 200 smoothly enters the cavity A between the inner layer coating 200 and the outer layer coating 300, and timely expands the outer layer coating 300 to block the branch blood vessel 400, and can also ensure that the blood flow in the inner layer coating 200 can slowly flow into the cavity A, ensuring the long-term formation of thrombus in the cavity A, and continuously preventing the occurrence of type II endoleak. Among them, the inner layer coating 200 can be ePTFE (Expanded Polytetrafluoroethylene, expanded polytetrafluoroethylene) coating, PET (Polyethylene terephthalate, polyester resin) single / multifilament film or other materials with a leakage range of 300 (ml / cm 2 / min)~1000(ml / cm 2 / min) range.

[0042] Optionally, a thrombogenic agent or villi are placed in the cavity A between the outer film 300 and the inner film 200. The thrombogenic agent is a chemical agent containing natural polysaccharide gum, Apelin-17 and other components that promote thrombosis.

[0043] (2) In some other embodiments of the present invention, the stent graft further comprises: a filler placed in the intercalation cavity A, the filler being used to expand the outer layer graft 300. The stent graft is implanted into the abdominal aortic aneurysm, and then the filler is injected into the intercalation cavity A between the outer layer graft 300 and the inner layer graft 200 through the filling window on the outer layer graft 300, thereby expanding the outer layer graft 300, and then the filling window on the outer layer graft 300 is blocked.

[0044] Optionally, the filler is silicone. Silicone's shape-shifting properties allow the outer coating 300 to fill tumors of varying structures, ensuring that the outer coating 300 effectively blocks blood flow backflow in the branch vessels 400. It can also effectively mitigate type I endoleaks caused by poor fit between the proximal and distal ends of the stent graft and the blood vessels. Of course, in some embodiments of the present invention, the filler can also be configured as other interventional filling materials.

[0045] like Figures 1 to 5 As shown, in some embodiments of the present invention, the outer coating 300 surrounds the barrier portion of the inner coating 200, and the proximal and distal ends of the outer coating 300 are sealed and fixed to the proximal and distal ends of the barrier portion respectively; the outer coating 300 is made of a flexible material, and the surface area of the outer coating 300 is greater than the surface area of the barrier portion. The surface area of the outer coating 300 is equal to or greater than the surface area of the inner wall of the aneurysm cavity of the abdominal aortic aneurysm, so that it can fully adhere to the inner wall of the aneurysm cavity. It should be noted that the barrier portion of the inner coating 200 refers to the portion of the inner coating 200 that separates the inner lumen of the inner coating 200 from the intervening cavity A, i.e., the portion of the inner coating 200 that corresponds to the outer coating 300 in the axial direction of the metal stent 100. This portion may refer to the circumferential surfaces of the proximal and distal ends of the inner coating 200, or to the circumferential surfaces of portions of the inner coating 200 other than the proximal and distal ends, thereby serving to separate the inner lumen of the inner coating 200 from the intervening cavity A between the inner coating 200 and the outer coating 300. In this manner, the outer coating 300 does not need to be made of an elastic material, i.e., it does not need to be expanded. This ensures that the outer coating 300 can be expanded by the blood flow's own minimal pressure, and further eliminates the need for specific material restrictions for the outer coating 300. It is understandable that the outer layer membrane 300 is made of a flexible material, i.e. a polymer soft material with good biocompatibility, and can be deformed under the action of force. Therefore, it is in a drooping state when not stretched, and can stand upright only when subjected to external force.

[0046] In some embodiments of the present invention, the material of the inner layer coating 200 and / or the outer layer coating 300 is at least one of PET, ePTFE or TPU (Thermoplastic polyurethanes). It should be noted that the outer layer coating 300 formed by the above materials also has a certain leakage rate, which is about 300 (ml / cm 2 / min)-1000(ml / cm 2 However, the flow rate and velocity of the fluid flowing from the inner coating 200 into the cavity A between the inner coating 200 and the outer coating 300 are too low, preventing this portion of fluid from leaking from the outer coating 300 into the aneurysm cavity of the abdominal aortic aneurysm. Even if leakage occurs, the amount is very small and has no impact on the human body, which can be ignored. Furthermore, approximately one month after surgery, leakage will cease due to endothelialization of the coating material. It should be noted that the cavity A formed between the outer coating 300 and the inner coating 200 is a closed space. That is, apart from leakage caused by the predetermined leakage amount, there are no other leaks in the outer coating 300 or the inner coating 200.

[0047] Optionally, the inner coating 200 is secured to the metal stent 100 by sewing or hot-melting; the proximal and distal ends of the outer coating 300 are respectively secured to the outer side of the inner coating 200 by sewing or hot-melting. It is understood that the inner coating 200 is entirely connected to the metal stent 100, i.e., it covers the metal stent 100. Optionally, the inner coating 200 is located on the inner or outer side of the metal stent 100, and the outer coating 300 is located on the outer side of the metal stent 100.

[0048] In some embodiments of the present invention, at least one visceral artery blood supply site is provided on the inner coating 200; the number of cavities A is greater than or equal to 2, and the cavities A are distributed sequentially from the proximal end to the distal end of the inner coating 200, with two adjacent cavities A separated on the distal and proximal sides of the corresponding visceral artery blood supply site. It should be noted that the visceral artery blood supply site is used to supply blood to visceral arteries 600, such as the bilateral renal arteries, the celiac trunk, and the superior mesenteric artery. In this way, the stent graft can ensure normal blood supply to the visceral arteries 600 while preventing blood flow backflow in the branch vessels 400, thereby avoiding the occurrence of serious complications. Optionally, a blood flow window is provided on the visceral artery blood supply site of the inner coating 200. Preferably, an embedded branch is provided in the inner coating 200, embedded in the blood flow window, and the embedded branch is used to install a branch vessel stent, which is used to supply blood to the visceral artery.

[0049] Optionally, the number of outer films 300 is greater than or equal to 2, and a cavity A is formed between each outer film 300 and the inner film 200. The number of outer films 300 is the same as the number of cavities A, that is, one outer film 300 forms one cavity A.

[0050] In other embodiments of the present invention, Figures 3 to 5 As shown, the inner layer covering 200 is provided with at least one visceral artery blood supply position; the outer layer covering 300 and the clamp cavity A are both 1, the outer layer covering 300 has at least one blood supply window and the portion of the outer layer covering 300 located around the blood supply window is fixed to the inner layer covering 200, and the blood supply window is communicated with the corresponding visceral artery blood supply position.

[0051] Optionally, the portion of the outer coating 300 located around the blood supply window is fixed to the inner coating 200 by heat melting or sewing.

[0052] In some embodiments of the present invention, the stent graft includes a main stent graft and a branch stent graft connected to the distal end of the main stent graft; the distal end of the outer stent graft 300 is fixed to the inner stent graft 200 of the branch stent graft. It should be noted that the branch stent graft is used to supply blood to the iliac artery. In this way, abdominal aortic aneurysms located in different parts of the abdomen can be treated, thereby expanding the application range of the stent graft. It is understood that the main stent graft refers to the unbranched portion of the stent graft, and the branch stent graft refers to the bifurcated portion of the stent graft.

[0053] Optionally, the distal end of the outer coating 300 is fixed to the proximal end of the inner coating 200 of the branch stent graft, or to the middle portion of the inner coating 200 of the branch stent graft, or to the distal end of the inner coating 200 of the branch stent graft. It should be noted that the middle portion of the inner coating 200 of the branch stent graft refers to the portion of the inner coating 200 of the branch stent graft located between the proximal end and the distal end.

[0054] Optionally, the outer coating 300 can form an arterial wall-adhering surface F2 when expanded (see Figures 3 to 5 When the outer coating 300 is expanded, the arterial wall contact surface F2 can contact the inner wall of the iliac artery 500, thereby preventing type I endoleak caused by loose contact between the distal end of the stent graft and the iliac artery 500.

[0055] The number and distribution of the outer coating 300 are related to the positional relationship between the proximal end of the branched stent graft, the branched blood vessels 400 and the visceral artery 600. Figures 2 to 5 To explain:

[0056] (1) Figure 2As shown, when the proximal end of the branch stent graft coincides with the iliac artery bifurcation 500a and the abdominal aortic aneurysm does not involve the visceral artery 600, the number of the outer coating 300 is one and the proximal end is arranged around the outside of the inner coating 200 of the main stent graft and the distal end is arranged around the proximal end of the branch stent graft to cover the branch vessel 400. It should be noted that Figure 2 When the outer covering membrane 300 shown in FIG is expanded, its outer surface forms the tumor cavity wall close-fitting surface F1.

[0057] When the inner layer film 200 has a certain leakage, the leakage of the inner layer film 200 in the short term after surgery can make Figure 2 The blood flows from top to bottom through the inner coating 200 and slowly enters the cavity A between the inner coating 200 and the outer coating 300, so that the outer coating 300 expands until it fills the entire aneurysm cavity of the abdominal aortic aneurysm. This can not only cover the branch blood vessels 400 on the abdominal aortic aneurysm, thereby blocking the backflow of blood in the branch blood vessels 400 and preventing type II endoleak, but also play a certain blocking role in type I endoleak caused by the loose fitting of the proximal and distal ends of the coated stent to the aortic blood vessels. At the same time, the slow blood flow can cause a thrombus to form in the cavity A between the inner coating 200 and the outer coating 300, continuously preventing the occurrence of type II endoleak.

[0058] (2) Figure 3 As shown, when the proximal end of the branch stent graft is located above the iliac artery bifurcation 500a and the abdominal aortic aneurysm does not involve the visceral artery 600, the number of the outer coating 300 is one and the proximal end is arranged around the outside of the inner coating 200 of the main stent graft and the distal end is arranged around the area between the proximal end of the branch stent graft and the iliac artery bifurcation 500a. It should be noted that Figure 3 When the outer covering 300 shown in the figure is expanded, the dotted lines serve as upper and lower boundaries. The outer surface above the boundaries constitutes the tumor cavity wall close-fitting surface F1, and the outer surface below the boundaries constitutes the arterial blood vessel wall close-fitting surface F2.

[0059] Similarly, when the inner layer coating 200 has a certain amount of leakage, then under the action of blood flow, the outer layer coating 300 expands to fill the entire aneurysm cavity of the abdominal aortic aneurysm and covers the branch blood vessels 400, and gradually produces a thrombus in the interspace A formed between the inner layer coating 200 and the outer layer coating 300, which can continuously prevent type II endoleak in the short and long term; at the same time, it also has a certain blocking effect on type I endoleak.

[0060] (3) Figure 4As shown, when the proximal end of the branch stent graft is located above the iliac artery bifurcation 500a, the abdominal aortic aneurysm involves the visceral artery 600, and the branch vessels 400 are respectively located at the distal and proximal ends of the visceral artery 600, the number of outer coatings 300 is two, namely the proximal outer coating 310 and the distal outer coating 320. The proximal outer coating 310 is arranged around the portion of the main stent graft located above the visceral artery 600 to cover the corresponding branch vessels 400. The proximal end of the distal outer coating 320 is arranged around the portion between the proximal end of the branch stent graft and the visceral artery 600, and the distal end is arranged around the portion between the proximal end of the branch stent graft and the iliac artery bifurcation 500a. It should be noted that Figure 4 When the proximal outer layer membrane 310 is expanded, its outer surface forms the tumor cavity wall close-fitting surface F1; Figure 4 When the distal outer coating 320 is expanded, the dotted line is used as the upper and lower boundaries. The outer surface above the boundary constitutes the tumor cavity wall close-fitting surface F1, and the outer surface below the boundary constitutes the arterial blood vessel wall close-fitting surface F2.

[0061] This type of covered stent structure can prevent type II endoleak; at the same time, as the proximal outer layer 310 and the distal outer layer 320 gradually expand and adhere to the inner wall of the abdominal aortic aneurysm cavity and the vascular wall of the iliac artery, type I endoleak can also be prevented.

[0062] (4) Figure 5 As shown, when the proximal end of the branch stent graft is located above the iliac artery bifurcation 500a, the abdominal aortic aneurysm involves the visceral artery 600, and the branch vessels 400 are located on both the distal and proximal sides of the visceral artery 600 and below the proximal end of the branch stent graft, the number of outer coatings 300 is two, namely the proximal outer coating 310 and the distal outer coating 320. The proximal outer coating 310 surrounds the area between the proximal end of the branch stent graft and the visceral artery 600, and the distal outer coating 320 surrounds the area of the branch stent graft located between the visceral artery 600 and the iliac artery bifurcation 500a. It should be noted that Figure 5 When the proximal outer coating 310 shown in FIG is expanded, its outer surface forms the arterial blood vessel wall close-fitting surface F2.

[0063] This type of covered stent structure can prevent type II endoleak; at the same time, as the distal outer coating 320 gradually expands and adheres to the inner wall of the iliac artery, it can prevent type I endoleak caused by the distal end of the covered stent not being tightly attached to the blood vessel.

[0064] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0065] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A stent graft, characterized in that: The stent graft comprises: a metal stent (100), an inner layer graft (200) and at least one outer layer graft (300); The inner layer coating (200) is arranged on the metal stent (100) to form an inner cavity that passes through the metal stent (100) along the axial direction. The outer layer coating (300) is arranged around the outer side of the inner layer coating (200). At least one sandwich cavity (A) is formed between the inner layer coating (200) and the at least one outer layer coating (300). The outer layer coating (300) can be expanded to form a tumor cavity wall close-fitting surface (F). The inner layer coating (200) has a preset leakage amount so that the blood flow in the inner layer coating (200) can pass through the inner layer coating (200) and flow into the cavity (A) between the outer layer coating (300) and the inner layer coating (200), thereby expanding the outer layer coating (300).

2. The stent graft according to claim 1, wherein: The preset leakage rate is 300 ml / cm 2 / min-1000 ml / cm 2 / min.

3. The stent graft according to claim 1, wherein: The clamp cavity (A) contains a thrombogenic agent or villi.

4. The stent graft according to any one of claims 1 to 3, characterized in that: The outer coating (300) surrounds the barrier portion of the inner coating (200), wherein the proximal and distal ends of the outer coating (300) are respectively sealed and fixed on the barrier portion; The outer coating (300) is made of a flexible material, and the surface area of the outer coating (300) is larger than the surface area of the barrier portion.

5. The stent graft according to any one of claims 1 to 3, characterized in that: The material of the inner layer coating (200) and / or the outer layer coating (300) is at least one of PET, ePTFE or Tpu.

6. The stent graft according to any one of claims 1 to 3, characterized in that: The proximal and distal ends of the outer layer coating (300) are fixed to the outer side of the inner layer coating (200) by sewing or hot melting.

7. The stent graft according to any one of claims 1 to 3, characterized in that: At least one visceral artery blood supply site is provided on the inner layer covering (200); The number of the cavities (A) is greater than or equal to 2, and the cavities (A) are distributed sequentially from the proximal end to the distal end of the inner layer coating (200), and two adjacent cavities (A) are separated at the distal and proximal sides of the corresponding visceral artery blood supply position.

8. The stent graft according to claim 7, wherein: The number of the outer coatings (300) is greater than or equal to 2, and the sandwich cavity (A) is formed between each outer coating (300) and the inner coating (200).

9. The stent graft according to any one of claims 1 to 3, characterized in that: At least one visceral artery blood supply site is provided on the inner layer covering (200); The number of the outer coating (300) and the number of the clamp cavity (A) are both one, the outer coating (300) has at least one blood supply window, and the portion of the outer coating (300) located around the blood supply window is fixed on the inner coating (200), and the blood supply window is communicated with the corresponding visceral artery blood supply position.

10. The stent graft according to any one of claims 1 to 3, characterized in that: The stent graft comprises a main stent graft and a branch stent graft connected to the distal end of the main stent graft; The distal end of the outer coating (300) is fixed to the inner coating (200) of the branch coated stent.

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