Covered stent

Abstract

The present invention provides a covered stent, which includes a covered section. The covered section includes a first framework and a covering film. The covering film is fixed to the first framework. The first framework includes a plurality of first structural units arranged axially at intervals. Each first structural unit has a plurality of protrusions facing the distal end and a plurality of depressions facing the proximal end. Adjacent two first structural units have a first preset angle in the circumferential direction. The minimum surface distance between the first depression closest to the proximal end of the covered section and the protrusion of the first structural unit adjacent axially to the proximal end is the largest among all the first surface distances in all configurations at the first preset angle, or the first surface distance between the first protrusion closest to the distal end of the covered section and the depression of the first structural unit adjacent axially to the distal end is the largest among all the first surface distances in all configurations at the first preset angle. When the covered stent is compressed and loaded into the delivery device, the situation of the covering film around the protrusions and depressions being broken or having openings can be reduced or even eliminated.

Description

Technical Field

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

[0002] With the development of minimally invasive surgery, transjugular intrahepatic portosystemic shunt (TIPS) was invented and used for portal hypertension in cirrhosis. The principle of transjugular intrahepatic portosystemic shunt (TIPS for short) is to use a special minimally invasive interventional treatment device, under the guidance of X-ray fluoroscopy, through the jugular vein to establish an artificial shunt channel between the main branches of the hepatic vein and the portal vein in the liver, and use a metal stent to maintain its permanent patency, so as to reduce portal hypertension and control and prevent complications such as rupture and bleeding of esophageal varicose veins. This method has low trauma, high success rate, low complications, wide indications, significant reduction of portal vein pressure, and reliable efficacy in controlling esophageal varicose bleeding. It is a new method for treating portal hypertension. It plays an extremely important role in the treatment of portal hypertension.

[0003] The most widely used stent in TIPS surgery is the TIPS covered stent. Compared with the bare stent, the covered stent can completely block the leakage of bile into the stent and the squeezing of liver tissue into the shunt, which significantly improves the patency of the shunt. Specifically, the TIPS covered stent usually includes a bare segment and a covered segment. The bare segment is used to position in the portal vein to ensure that the blood perfusion of the portal vein to other branches is not affected. The covered segment includes a first skeleton and a membrane arranged on the first skeleton, which is used to position in the liver and hepatic vein to effectively prevent bile erosion.

[0004] Before delivering the TIPS covered stent, the TIPS covered stent needs to be pressed and gripped in a compressed state and loaded into a delivery device, and then the TIPS covered stent is delivered to the position from the liver parenchyma to the portal vein by the delivery device and released. In practical applications, in order to improve the comprehensive performance of the stent, a non-spiral covered stent composed of stents with different wave heights will be designed. For non-spiral covered stents with inconsistent wave heights of the stent ring, the distance between adjacent depressions and protrusions in the axial direction may be closer. If the spatial configuration of the stent is not properly arranged, the covered stent may be easily thinned and ruptured during the pressing and gripping process. Once the covering is ruptured, bile may enter the inside of the TIPS covered stent through the rupture after the stent is implanted in the human body. If a large amount of bile leaks in a short period of time, a strong inflammatory response will occur, inhibiting the growth and function of endothelial cells, and promoting thrombosis, thereby causing early stenosis and occlusion of the TIPS covered stent; if a small amount of bile leaks in, it may cause a milder inflammatory response, promote pseudointimal hyperplasia, and ultimately lead to medium- and long-term stenosis of the TIPS covered stent. Summary of the invention

[0005] The purpose of the embodiments of the present invention is to provide a covered stent to solve one or more of the above technical problems.

[0006] To achieve the above object, the technical solution adopted by the present invention is: The present invention provides a covered stent, including a covered section, and the covered section includes a first framework and a covering; the covering is fixed to the first framework.

[0007] The first framework includes a plurality of first structural units arranged at intervals in the axial direction. The first structural unit has a plurality of protrusions facing the distal end and a plurality of depressions facing the proximal end. The protrusions and the depressions are arranged at intervals in sequence and are connected end to end.

[0008] Among the plurality of depressions, there is a first depression. The distance from the first depression to the proximal end of the covered section is less than the distance from the remaining depressions to the proximal end of the covered section. The first structural unit and the first structural unit adjacent to the axial proximal end form a plurality of configurations due to different circumferential position relationships. In each configuration, there is a first curved surface distance between the first depression and the protrusions of the first structural unit adjacent to the axial proximal end. The first curved surface distance is the smallest among the curved surface distances between the first depression and all the protrusions of the first structural unit adjacent to the axial proximal end. The first structural unit where the first depression is located and the first structural unit adjacent to the axial proximal end have a first preset angle in the circumferential direction. The first curved surface distance in the configuration corresponding to the first preset angle is the largest among the first curved surface distances in the plurality of configurations; or,

[0009] Among the plurality of protrusions, there is a first protrusion. The distance from the first protrusion to the distal end of the covered section is less than the distance from the remaining protrusions to the distal end of the covered section. The first structural unit and the first structural unit adjacent to the axial distal end form a plurality of configurations due to different circumferential position relationships. In each configuration, there is a first curved surface distance between the first protrusion and the depressions of the first structural unit adjacent to the axial distal end. The first curved surface distance is the smallest among the curved surface distances between the first protrusion and all the depressions of the first structural unit adjacent to the axial distal end. The first structural unit where the first protrusion is located and the first structural unit adjacent to the axial distal end have a first preset angle in the circumferential direction. The first curved surface distance in the configuration corresponding to the first preset angle is the largest among the first curved surface distances in the plurality of configurations.

[0010] In one embodiment, when there are a plurality of first depressions, the first curved surface distance is the smallest among the curved surface distances from all the first depressions to all the protrusions of the first structural unit adjacent to the axial proximal end.

[0011] When there are multiple first protrusions, the first curved surface distance is the smallest among the curved surface distances from all the first protrusions to all the depressions of the first structural unit adjacent to the axial distal end.

[0012] In one embodiment, when the first structural unit has the first depression, the distances from all the protrusions of the first structural unit adjacent to the axial proximal end to the distal end of the film covering section are the same;

[0013] Alternatively, when the first structural unit has the first protrusion, the distances from all the depressions of the first structural unit adjacent to the axial distal end to the proximal end of the film covering section are the same.

[0014] In one embodiment, the first structural unit includes N repeating structural units, and the N repeating structural units are connected in sequence along the circumferential direction. The head end of the first repeating structural unit is connected to the tail end of the Nth repeating structural unit, where N is a natural number greater than 1.

[0015] In one embodiment, the number of the repeating structural units is four. In the direction from the proximal end to the distal end, the structure of the repeating structural unit is "M" - shaped, or the structure of the repeating structural unit is "W" - shaped.

[0016] In one embodiment, it further includes a reinforcing film, and the reinforcing film covers the proximal part of the first depression, the distal part of the protrusion adjacent to the axial proximal end of the first depression and having the first curved surface distance, and the film covering between the first depression and the protrusion;

[0017] Alternatively, the reinforcing film covers the distal part of the first protrusion, the proximal part of the depression adjacent to the axial distal end of the first protrusion and having the first curved surface distance, and the film covering between the first protrusion and the depression.

[0018] In one embodiment, the first structural unit has multiple first depressions, and the reinforcing film winds circumferentially around the proximal part of each first depression, the distal part of the protrusion adjacent to the axial proximal end of the first depression and having the first curved surface distance, and the film covering between the first depression and the protrusion;

[0019] Or,

[0020] The first structural unit has multiple first protrusions, and the reinforcing film winds circumferentially around the distal part of each first protrusion, the proximal part of the depression adjacent to the axial distal end of the first protrusion and having the first curved surface distance, and the film covering between the first protrusion and the depression.

[0021] In one embodiment, in the axial direction, the length of the reinforcing film covering the first convex portion is greater than 0 mm and less than 2.5 mm, and / or the length of the reinforcing film covering the concave portion adjacent to the axial distal end of the first convex and having a first curved surface distance is greater than 0 mm and less than 2.5 mm; or,

[0022] In the axial direction, the length of the reinforcing film covering the first concave portion is greater than 0 mm and less than 2.5 mm, and / or the length of the reinforcing film covering the convex portion adjacent to the axial distal end of the first concave and having a first curved surface distance is greater than 0 mm and less than 2.5 mm.

[0023] In one embodiment, the yield strength of the reinforcing film is greater than the yield strength of the film coating.

[0024] In one embodiment, the covered stent further includes a bare segment at the distal end of the covered segment, and the radial dimension of at least a part of the bare segment is greater than the radial dimension of the covered segment.

[0025] The covered stent provided by the present invention includes a covered segment, the covered segment includes a first framework and a film coating, the film coating is fixed to the first framework, the first framework includes a plurality of first structural units arranged at intervals in the axial direction, and adjacent two first structural units have a first preset angle in the circumferential direction. The minimum curved surface distance between the first concave closest to the proximal end of the covered segment and the convex of the first structural unit adjacent to the axial proximal end is the largest among the first curved surface distances in all configurations at the first preset angle, or the first curved surface distance between the first convex closest to the distal end of the covered segment and the concave of the first structural unit adjacent to the axial distal end is the largest among the first curved surface distances in all configurations at the first preset angle. When loading the covered stent into the delivery device, the situation of the film coating cracking or having a break during the crimping process can be reduced, so that after the covered stent is implanted in the human body, the covered segment can effectively prevent liquid from undesirably entering the inside or outside of the stent, causing the covered stent to fail. For example, bile enters the inside of the stent and liver tissue squeezes towards the inside of the stent, resulting in stenosis or occlusion of the covered stent. Another example is that blood flows from inside the stent to the aortic aneurysm through the break in the film coating, causing the pressure of the aortic aneurysm to still increase and possibly eventually leading to aortic rupture. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0027] Figure 1Schematic structural diagram of a covered stent provided by an embodiment of the present invention;

[0028] Figure 2 For Figure 1 Partial unfolded schematic diagram under the configuration where the first structural units of the covered section of the covered stent shown are axially aligned;

[0029] Figure 3 For Figure 2 Partial unfolded schematic diagram under the configuration where the first structural units in the covered section of the covered stent shown are axially rotated by a certain angle;

[0030] Figure 4 Partial structural schematic diagram of the covered section of a covered stent provided by another embodiment of the present invention. Detailed implementation manners

[0031] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0032] In the description of the present invention, it should be understood that the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0033] In addition, in this application, unless otherwise clearly specified and defined, terms such as "connected", "coupled", "fixed", "installed" should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two components or the interaction relationship between two components. Unless otherwise clearly defined, for those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0034] It should be understood that the orientation or positional relationship indicated by terms such as "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is 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 thus should not be construed as a limitation to the present invention.

[0035] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0036] The present invention provides a covered stent to solve the problem that the covering of the covered stent becomes thinner or even ruptures during crimping. Specifically, the covered stent includes a covered section, and the covered section includes a first framework and a covering; the covering is fixed to the first framework.

[0037] The first framework includes a plurality of first structural units arranged at intervals in the axial direction. The first structural unit has a plurality of protrusions facing the distal end and a plurality of depressions facing the proximal end. The protrusions and the depressions are arranged at intervals in sequence and are connected end to end.

[0038] Among the plurality of depressions, there is a first depression. The distance of the first depression from the proximal end of the covered section is less than the distance of the remaining depressions from the proximal end of the covered section. The first structural unit and the first structural unit adjacent to the axial proximal end form a plurality of configurations with different circumferential positional relationships. In each configuration, there is a first curved surface distance between the first depression and the protrusions of the first structural unit adjacent to the axial proximal end. The first curved surface distance is the smallest among the curved surface distances between the first depression and all the protrusions of the first structural unit adjacent to the axial proximal end. The first structural unit where the first depression is located and the first structural unit adjacent to the axial proximal end have a first preset angle in the circumferential direction. The first curved surface distance in the configuration corresponding to the first preset angle is the largest among the first curved surface distances corresponding to the plurality of configurations; or,

[0039] Among the multiple protrusions, there is a first protrusion. The distance of the first protrusion from the distal end of the film-covered section is less than the distances of the remaining protrusions from the distal end of the film-covered section. The first structural unit and the first structural unit adjacent to the axial distal end form multiple configurations with different circumferential position relationships. In each configuration, there is a first curved surface distance between the first protrusion and the depression of the first structural unit adjacent to the axial distal end. The first curved surface distance is the smallest among the curved surface distances between the first protrusion and all the depressions of the first structural unit adjacent to the axial distal end. The first structural unit where the first protrusion is located and the first structural unit adjacent to the axial distal end have a first preset angle in the circumferential direction. The first curved surface distance in the configuration corresponding to the first preset angle is the largest among the first curved surface distances corresponding to the multiple configurations.

[0040] The film-covered stent of the present invention can not only be used as a TIPS film-covered stent, but also as an abdominal aortic film-covered stent for treating diseases such as abdominal aortic dissection and abdominal aortic aneurysm, a thoracic aortic film-covered stent for treating diseases such as thoracic aortic aneurysm and thoracic aortic dissection, and a film-covered stent for treating other diseases.

[0041] The film-covered stent provided by the present invention will be described in detail below in combination with its application in the TIPS operation.

[0042] In each embodiment of the present invention, the defined term "distal end" refers to the end or side far from the operator during the surgical operation, and the "proximal end" refers to the end or side close to the operator during the surgical operation. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the present invention in the specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0043] Embodiment 1:

[0044] Figure 1 It is a schematic structural diagram of a film-covered stent provided for an embodiment of the present invention. Please refer to Figure 1 , this embodiment provides a film-covered stent for establishing a blood flow channel between the hepatic vein and the portal vein. The film-covered stent includes a film-covered section 1, and the film-covered section 1 is used to be placed in the liver parenchyma and communicate with the hepatic vein.

[0045] The film covering section 1 includes a first framework 11 and a film covering 12. The first framework 11 plays a supporting role, and the film covering 12 is fixed to the first framework 11. For TIPS, the first framework 11 supports the artificial shunt channel located in the liver parenchyma; for the abdominal aorta and the thoracic aorta, the first framework 11 supports the abdominal aorta and the thoracic aorta blood vessels. The first framework 11 includes a plurality of first structural units arranged at axial intervals. The first structural unit has a plurality of protrusions 111 facing the distal end and a plurality of depressions 112 facing the proximal end. The protrusions 111 and the depressions 112 are arranged at intervals in sequence, that is, the depressions 112 are arranged on both sides of the protrusion 111, and the protrusions 111 are arranged on both sides of the depression 112. In this embodiment, the first structural unit has the same structure as the axially adjacent first structural unit. In other embodiments, the first structural unit has a different structure from the axially adjacent first structural unit. For example, the number of the protrusions 111 and the depressions 112 in the first structural unit is different, or at least some of the protrusions 111 and the depressions 112 in the first structural unit have different shapes.

[0046] Preferably, the first structural unit includes N repeating structural units 113. The N repeating structural units are sequentially connected in the circumferential direction. The head end of the first repeating structural unit is connected to the tail end of the Nth repeating structural unit, where N is a natural number greater than 1. There is no particular limitation on the shape of the repeating structural unit 113 in this embodiment, as long as the repeating structural units 113 are sequentially connected to form the protrusions 111 facing the distal end and the depressions 112 facing the proximal end. The distances of the plurality of depressions 112 in the first structural unit from the proximal end of the film covering section are different. For example, the repeating structural unit 113 can be a structure with protrusions 111 such as a tooth shape, an arc shape, a parabola, etc., and a depression 112 is formed between two adjacent repeating structural units 113. In this way, the protrusions 111 and the depressions 112 are arranged at intervals, that is, the depressions 112 are on both circumferential sides of the protrusions 111, and the protrusions 111 are on both circumferential sides of the depressions 112. In other embodiments, the repeating structural unit 113 can also be a structure with depressions 112, and protrusions 111 are formed between the repeating structural units 113. In other embodiments, the repeating structural unit 113 can also be a structure with depressions 112 and protrusions 111, and the depressions 112 and the protrusions 111 are arranged at intervals. For example, the repeating structural unit 113 is a wavy shape, a sine wave shape, etc. The first framework 11 is a biocompatible alloy material with shape memory function, such as nitinol alloy. In other embodiments, the first framework 11 can be a polymer material.

[0047] Among the multiple depressions 112 of the first structural unit, there is a first depression 112A, which is defined as having a distance from the proximal end of the membrane-covered section 1 smaller than the distances of the remaining depressions 112 from the proximal end of the membrane-covered section 1, that is, the first depression 112A is the depression 112 with the smallest distance from the proximal end of the membrane-covered section 1. Each first structural unit and the axially adjacent first structural unit can form different configurations due to different circumferential relative position relationships. In this embodiment, in each configuration formed by the first structural unit and the axially proximal adjacent first structural unit, there is a first curved surface distance between the first depression 112A and the protrusion 111 in the axially proximal adjacent first structural unit, and the first curved surface distance is the smallest among the curved surface distances between the first depression 112A and all the protrusions 111 of the axially proximal adjacent first structural unit. Thus, the first structural unit where the first depression 112A is located and the axially proximal adjacent first structural unit have multiple configurations due to different circumferential relative positions, and each configuration has a first curved surface distance. The first structural unit where the first depression 112A is located in this embodiment and the axially proximal adjacent first structural unit have a first preset angle in the circumferential direction, and the first curved surface distance in the configuration corresponding to the first preset angle is the largest among the first curved surface distances of all the above configurations. The "curved surface distance" here is the shortest distance between the depression and the protrusion along the curved surface. That is, when the curved surface is unfolded into a plane, it is the straight-line distance between the depression and the protrusion.

[0048] Each first structural unit and the axially adjacent first structural unit are arranged in this way. When the obtained membrane-covered stent is loaded into the delivery device, due to the maximization of the minimum curved surface distance (i.e., the first curved surface distance) between the first depression 112A and the axially proximal adjacent protrusion 111, the situation of the membrane between the depression 112 and the protrusion 111 being broken or torn during the crimping process can be reduced. Thus, after the membrane-covered stent is implanted in the human body, the membrane-covered section can effectively prevent the liquid from undesirably entering the inside or outside of the stent, so that the membrane-covered stent fails. For example, bile enters the inside of the stent and liver tissue squeezes towards the inside of the stent, and then the situation of the membrane-covered stent being stenosed or occluded occurs.

[0049] Figure 2 For Figure 1 the local unfolded schematic diagram of the axially aligned configuration of the first structural unit of the membrane-covered section of the shown membrane-covered stent, Figure 3 For Figure 2 the local unfolded schematic diagram of the configuration after the first structural unit in the membrane-covered section of the shown membrane-covered stent rotates by a certain angle. The following combines the manufacturing process of the membrane-covered stent to detail the principle that the membrane-covered stent can reduce the rupture and tearing of the membrane during the loading into the delivery device.

[0050] As Figures 1-3As shown, each first structural unit of the covered stent includes eight protrusions 111 and eight depressions 112. The eight protrusions 111 and the eight depressions 112 are arranged at intervals in sequence and are connected end to end. That is, on both circumferential sides of each protrusion 111 are depressions 112. Similarly, on both circumferential sides of each depression 112 are protrusions 111. In this embodiment, the eight protrusions 111 are equidistant from the proximal end of the covered section 1, while the eight depressions 112 are not equidistant from the proximal end of the covered section 1. More specifically, among the eight depressions 112, the distances of four first depressions 112A to the proximal end are less than the distances of the remaining four depressions 112 to the proximal end. In this embodiment, all the first structural units have the same structure. In this embodiment, in the direction from the proximal end to the distal end, the repeating structural unit includes four repeating structural units, and the structure of each repeating structural unit is "M"-shaped. Further, the depressions 112 are also formed between the "M"-shaped repeating structural units, and the distance of this depression 112 from the proximal end of the covered section is less than the distance of the depression in the "M"-shaped repeating structural unit from the proximal end of the covered section.

[0051] Further, Figures 1-2 A configuration in which each first structural unit is circumferentially aligned with an adjacent first structural unit is shown. Specifically, any protrusion 111 has the same circumferential position as the axially adjacent protrusion 111. Preferably, any protrusion 111 and the axially adjacent protrusion 111 are located on the same straight line parallel to the axis of the covered section 1. That is, the projections of the protrusions 111 on a plane perpendicular to the axis of the covered stent overlap. Similarly, any depression 112 has the same circumferential position as the axially adjacent depression 112. Preferably, any depression 112 and the axially adjacent depression 112 are located on the same straight line parallel to the axis of the covered section.

[0052] After determining the first depression 112A, the first surface distance is determined according to the first depression 112A. If the first structural unit has multiple first depressions 112A, first obtain the minimum surface distance from each first depression to the axially proximal adjacent protrusion 111, and then obtain the minimum value from all the minimum surface distances of the first depressions 112A as the first surface distance. Taking Figure 2Taking the first recess 112A in the first structural unit I as an example, traverse the eight protrusions 111B in the first structural unit II adjacent to the axial proximal end, obtain the surface distances from these eight protrusions 111B to the first recess 112A, and obtain the minimum surface distance. In this embodiment, among the eight protrusions 111 adjacent to the axial proximal end, the surface distance L11 between the protrusion 111 that is circumferentially adjacent to the first recess 112A in the counterclockwise direction and the first recess 112A is the smallest. Since this embodiment has four first recesses 112A, the first surface distances of these four recesses 112A are obtained respectively, which are L11, L12, L13, and L14. Since in this embodiment, the protrusions 111 and the recesses 112 are symmetrically arranged on the first structural unit. Therefore, in this embodiment, the minimum surface distances of the four first recesses 112A are equal, so the minimum surface distance of these four first recesses can be represented by L11 and used as the first surface distance. In other embodiments, the minimum surface distances of these four first recesses 112A may not be equal, then take the smallest of these four minimum surface distances as the first surface distance min(L11, L12, L13, L14). That is, at this time, the first surface distance is the smallest among the surface distances from all the first recesses 112A to all the protrusions of the first structural unit II adjacent to the axial proximal end. In this way, the minimum first surface distance between the first structural unit I and the first structural unit II in the current configuration can be obtained.

[0053] When the covered stent is compressed and loaded into the delivery device, the areas where the covering film becomes thinner and ruptures mostly occur between the first recess 112A of the first structural unit I and the protrusion 111 (for example Figure 2 in the first structural unit II adjacent to the axial proximal end, the protrusion 111 that is circumferentially adjacent to the first recess 112A in the counterclockwise direction). In order to prevent the covering film 12 from being squeezed and thinned or ruptured, when the shapes, sizes, and numbers of the protrusions 111 and recesses 112 in the first structural unit are determined, the covering film section 1 of the covered stent in this embodiment is selected from the multiple configurations formed by the circumferential relative position relationship between the first structural unit I and the first structural unit II adjacent to the axial proximal end, and the configuration corresponding to the maximum first surface distance is selected.

[0054] To facilitate the description of the circumferential relative position relationship between the first structural unit I and the first structural unit II adjacent to the axial proximal end, the angle between the first structural unit I and the first structural unit II is used to represent the corresponding configuration. First, it is necessary to be based on a preset circumferential reference. For example, in this embodiment, it is based on the circumferential alignment of the first structural unit I and the first structural unit II. As Figure 2 shown, the angle of the second structural unit II relative to the first structural unit I in the circumferential direction can be 0°. As Figure 3As shown, the angle of the second structural unit II relative to the first structural unit I in the circumferential direction can be 15°. In this configuration, the minimum surface distances of the plurality of first recesses 112A in the first structural unit I are L21, L23, L24, and L25 respectively. Therefore, the first surface distance in the first structural unit I is min(L21, L23, L24, L25). In this embodiment, since L21, L23, L24, and L25 are equal, the first surface distance in the current configuration can be represented by L21.

[0055] Furthermore, the first surface distance of the first structural unit I is obtained in other configurations. Theoretically, since there are an infinite number of circumferential relative position relationships between the first structural unit I and the first structural unit II adjacent to the axial proximal end, there are an infinite number of configurations and the first surface distances in these configurations. Generally, 8 to 16 representative configurations can be set, and the first surface distances of the first recesses 112A in the first structural unit I in these configurations are obtained, and then the configuration and the angle corresponding to the maximum first surface distance are selected as the configuration of the first structural unit I and the first structural unit II and the first preset angle of the covered stent covered section in this embodiment.

[0056] Further, according to the structural characteristics of the first structural unit, the number of configurations can be further optimized. As described above, the first structural unit of this embodiment includes four identical repeating structural units, and the repeating structural unit is in an "M" shape (observed from the proximal end to the distal end), that is, there are two types of depressions, depression I and depression II, where depression I is the first depression, and depression I and depression II are arranged alternately. Therefore, taking the circumferential alignment position of the first structural unit I and the first structural unit II as a reference (i.e., 0°), when the first structural unit I and the first structural unit II are rotated from 0° to 90°, all configurations and the first surface distance under each configuration can be obtained. Further, in this embodiment, the first surface distances of the first structural unit I under 10 configurations are obtained, that is, between each configuration, the first structural unit I and the first structural unit II are relatively rotated by 9°, and 10 first surface distances are sequentially obtained. The maximum value among the 10 first surface distances, max(L11, L21,..., L101), is taken, and the corresponding angle is used as the first preset angle between the first structural unit I and the first structural unit II in the covered membrane section of the covered stent of this embodiment. In this embodiment, L11 is the maximum value. When the first structural unit I and the first structural unit II are circumferentially aligned, that is, when the first preset angle is 0°, the first surface distance is the largest. Therefore, the configuration of the first structural unit I when the first structural unit I and the first structural unit II are circumferentially aligned is the configuration of the first structural unit I in the covered membrane section of the covered stent of this embodiment. By analogy, the circumferential relative position relationship between each first structural unit and the axially adjacent first structural unit can be obtained, that is, the configuration between each first structural unit and the axially adjacent first structural unit can be obtained, and then the configuration of the entire covered membrane section can be obtained.

[0057] After determining the configurations of any two adjacent first structural units in the above manner, the first surface distance between the two adjacent first structural units can be maximized, improving the covered membrane part between the two adjacent first structural units that is most vulnerable to extrusion, thereby minimizing or even eliminating the probability that the covered membrane between the two adjacent first structural units becomes thinner or even ruptures or tears due to extrusion.

[0058] In the covered stent of this embodiment, the distances from all the protrusions 111 on the first structural unit II to the distal first structural unit I are equal. In other embodiments, the distances from all the protrusions 111 on the first structural unit to the proximal end of the covered membrane section may also be unequal. At this time, the method for obtaining the circumferential position relationship between two adjacent first structural units on the covered stent, that is, the first preset angle between two adjacent first structural units, is similar to that of the above embodiment.

[0059] In this embodiment, the first structural unit includes four identical repeating structural units, and the structure of the repeating structural unit is "M" shaped. In other embodiments, the number of repeating structural units can be greater than four or less than four, and the shape of the repeating structural unit can be other shapes.

[0060] In the covered stent of this embodiment, all the protrusions on the first structural unit II are equidistant from the distal end of the covered section 1. In other embodiments, the distances of all the protrusions on the first structural unit II from the distal end of the covered section 1 can also be unequal.

[0061] Further, please refer to Figures 1-3 , the covered stent further includes a reinforcing film 13, and the reinforcing film 13 covers the proximal part of the first recess 112A, the distal part of the protrusion 111 that is axially proximally adjacent to the first recess 112A and has a first curved surface distance, and the covered film between the first recess 112A and the protrusion 111. In the covered stent of this embodiment, by adding a layer of reinforcing film 13 to the protrusion 111, the first recess 112A, and the covered film 12 region therebetween, the thickness of the corresponding part is increased, and together with the covered film 12, the yield strength is improved, and the occurrence of thinning and breakage of the covered film 12 can be effectively reduced. The material of the reinforcing film 13 in this embodiment can be similar to the material of the covered film 12, for example, it can be PTFE material, ePTFE material, etc. In other embodiments, the material of the reinforcing film 13 can be selected as a material with a yield strength greater than that of the covered film 13 to better protect the covered film 12. There are no special restrictions on the fixing method of the reinforcing film 13 to the covered film 12, the protrusion 111, and the recess 112 in this embodiment. For example, the covered film 12 is fixed by bonding, suturing, etc.

[0062] Further, the reinforcing film 13 is wound circumferentially around the proximal part of the first recess 112A, the proximal part of the protrusion that is axially proximally adjacent to the first recess 112A and has a first curved surface distance, and the covered film between the first recess 112A and the protrusion.

[0063] Further, the axial length of the part of the reinforcing film covering the first recess 112A and / or the part of the protrusion that is axially proximally adjacent to the first recess 112A and has a first curved surface distance is greater than 0 mm and less than 2.5 mm, preferably 0.5 - 1.5 mm. The reinforcing film 13 in this embodiment can increase the thickness and strength of the covered film 12 between the protrusion 111 and the corresponding recess 112, and to the greatest extent avoid the thinning and breakage of the covered film 12 due to extrusion during crimping. At the same time, the width of the reinforcing film 13 in the axial direction needs to be within a certain range, and try to avoid significantly increasing the thickness of the covered stent due to excessive increase in the area of the reinforcing film 13, thereby increasing the difficulty of crimping the covered stent.

[0064] Embodiment Two:

[0065] Figure 4 A partial structural schematic diagram of the covered segment of the covered stent provided for an embodiment of the present invention. Please refer to Figure 4 , this embodiment provides a covered stent for establishing a blood flow channel between the hepatic vein and the portal vein. The covered stent includes a covered segment 1, and the covered segment 1 is used to be placed in the hepatic parenchyma and communicate with the hepatic vein.

[0066] Similar to Embodiment 1, the covered segment 1 includes a first framework 11 and a covering 12. The first framework 11 plays a supporting role, and the covering 12 is fixed to the first framework 11. The covering 12 can be fixed to the outer surface and / or the inner surface of the first framework 11. For TIPS, the first framework 11 supports the artificial shunt channel located in the hepatic parenchyma; for the abdominal aorta and the thoracic aorta, the first framework 11 supports the abdominal aorta and the thoracic aorta blood vessels. The first framework 11 includes a plurality of first structural units arranged at axial intervals. The first structural unit has a plurality of protrusions 111 facing the distal end and a plurality of depressions 112 facing the proximal end. The protrusions 111 and the depressions 112 are arranged at intervals in sequence. That is, depressions 112 are provided on both sides of the protrusion 111, and protrusions 111 are provided on both sides of the depression 112. In this embodiment, the first structural unit is consistent with the axially adjacent first structural unit in structure. In other embodiments, the first structural unit is inconsistent with the axially adjacent first structural unit in structure. For example, the number of protrusions 111 and depressions 112 in the first structural unit is inconsistent, or for another example, at least part of the shapes of the protrusions 111 and depressions 112 in the first structural unit is inconsistent.

[0067] The difference from Embodiment 1 is that the protrusion 111 of this embodiment includes a first protrusion 111A closest to the distal end of the covered segment 1. There is a first curved surface distance between the first protrusion 111A of the first structural unit I and the depression 112 of the axially distal adjacent first structural unit II. The first curved surface distance is the smallest among the curved surface distances between the first protrusion 111A of the first structural unit I and all the depressions 112 of the axially distal adjacent first structural unit II. The first structural unit I where the first protrusion 111A is located and the axially distal adjacent first structural unit II have a first preset angle in the circumferential direction. The first curved surface distance in the configuration corresponding to the first preset angle is the largest among the first curved surface distances in the many configurations formed by different circumferential relative positions between the first structural unit I where the first protrusion 111A is located and the axially distal adjacent first structural unit II.

[0068] In the covered stent of this embodiment, the first structural unit I has four first protrusions 111A, and the first curved surface distance is the smallest among the curved surface distances from all the first protrusions 111A to all the depressions of the axially distal adjacent first structural unit II.

[0069] In the covered stent of this embodiment, the distances from all the depressions on the first structural unit II to the proximal end of the covered section 1 are equal. In other embodiments, the distances from all the depressions on the first structural unit II to the proximal end of the covered section 1 may also be unequal.

[0070] The first structural unit of this embodiment includes four identical first repeating structures, and the first repeating structure is in a "W" shape (observed from the proximal end to the distal end). That is, there are two types of protrusions, protrusion I and protrusion II, where protrusion I is the first protrusion, and protrusion I and protrusion II are arranged alternately.

[0071] When the covered stent of this embodiment is loaded into the delivery device, it can reduce the occurrence of rupture and breakage of the covering film during the crimping process. The principle is the same as that of the first embodiment, and will not be elaborated in this embodiment.

[0072] Furthermore, the covered stent further includes a reinforcing film 13. The reinforcing film 13 covers the distal part of the first protrusion 111A, the proximal part of the depression that is axially distal to the first protrusion 111A and has a first curved surface distance, and the covering film between the first protrusion 111A and the depression. In the covered stent of this embodiment, by adding a layer of reinforcing film 13 to the depression 112, the first protrusion 111A, and the covering film 12 area between the two, the thickness of the corresponding part is increased, and together with the covering film 12, the yield strength is improved, which can effectively reduce the occurrence of thinning and breakage of the covering film 12. The material of the reinforcing film 13 in this embodiment can be similar to the material of the covering film 12, for example, it can be PTFE material, ePTFE material, etc. In other embodiments, the material of the reinforcing film 13 can be selected as a material with a yield strength greater than that of the covering film 13 to better protect the covering film 12. This embodiment has no special restrictions on the fixing method of the reinforcing film 13 to the covering film 12, the protrusion 111, and the depression 112. For example, it can be fixed by bonding, suturing, etc.

[0073] Furthermore, the reinforcing film 13 is wound circumferentially around the distal part of the first protrusion 111A, the proximal part of the depression that is axially distal to the first protrusion 111A and has a first curved surface distance, and the covering film between the first protrusion 111A and the depression. Further, the axial length of the part of the reinforcing film covering the first protrusion 111A and / or the part of the reinforcing film covering the depression that is axially distal to the first protrusion 111A and has a first curved surface distance is greater than 0 mm and less than 2.5 mm, preferably 0.5 - 1.5 mm. The reinforcing film 13 of this embodiment can increase the thickness and strength of the covering film 12 between the protrusion 111 and the corresponding depression 112, and to the greatest extent avoid the thinning and breakage of the covering film 12 due to extrusion during crimping. At the same time, the width of the reinforcing film 13 in the axial direction needs to be within a certain range, and try to avoid significantly increasing the thickness of the covered stent due to excessive increase in the area of the reinforcing film 13, thereby increasing the difficulty of crimping the covered stent.

[0074] In the above embodiments, the membrane 12 can be fixed on the outer side of the first skeleton 11 to prevent liquid from flowing into the membrane section 1 or flowing out of the membrane section 1. For TIPS, the membrane 12 can prevent bile in the liver parenchyma from entering the shunt channel, causing stenosis of the membrane stent. In other embodiments, the membrane 12 is fixed on the inner side of the first skeleton 11. Alternatively, the membrane 12 is fixed on the inner and outer sides of the first skeleton 11. The membranes 12 provided on both sides of the first skeleton 11 can further prevent the penetration of liquid in the liver parenchyma. Preferably, the proximal shape of the membrane 12 matches the proximal shape of the first skeleton 11. After the membrane stent is implanted, since the proximal shape of the membrane 12 matches the proximal shape of the first skeleton 11, there will be no unexpanded membrane 12 folding towards the inner side of the shunt channel at the proximal end face of the stent, affecting the inner cavity space of the shunt channel.

[0075] There is no particular limitation on the fixing method of the membrane 12 and the first skeleton 11 in the above embodiments. For example, the membrane 12 and the first skeleton 11 are fixed by bonding, suturing, anchoring, sintering, etc. The membrane 12 can be made of PTFE material or ePTFE material.

[0076] Please continue to refer to Figure 1 , in the above embodiments, the membrane stent further includes a bare section 2 at the distal end of the membrane section 1. The bare section 2 is used to be placed in the portal vein through the puncture port to play a role in connection and fixation. The radial dimension of at least a part of the bare section 2 is larger than the radial dimension of the membrane section 1. Further, the bare section 2 includes a second skeleton 21. Among them, the second skeleton 21 is cylindrical, and the radial dimension of at least a part of the second skeleton 21 is larger than the radial dimension of the first skeleton 11. For example, the radial dimension of the proximal end (i.e., the end connected to the membrane section 1) of the second skeleton 21 is equal to the radial dimension of the first skeleton 11, but smaller than the radial dimension of the distal end (far from the membrane section 1). In this way, when the membrane stent is impacted by blood flow, the bare section 2 located in the portal vein helps to slow down the impact of blood flow on the stent, causing the membrane stent to move. In the above embodiments, the second skeleton 21 includes a plurality of second structural units, and the plurality of second structural units are axially distributed along the bare section 2. There is no particular limitation on the shape of the second structural unit in this embodiment. For example, the second structural unit is wavy, connected end to end, and the axially adjacent second structural units are intertwined with each other, that is, the protrusion of one second structural unit is intertwined with the depression of another axially adjacent second structural unit. Similarly, the second skeleton 21 is made of an alloy material with shape memory function, such as nitinol alloy. In other embodiments, the second skeleton 21 can also be made of a biocompatible polymer material.

[0077] Please refer to Figure 1, Further, the above-mentioned covered stent further includes a radiopaque marker 3, which is used to know the position of the covered stent in the body through imaging equipment, such as X-ray, during the implantation process of the covered stent. The radiopaque marker 3 is generally made of a metal radiopaque material that can be radiographed under imaging equipment, such as tungsten, gold, platinum, iridium, tantalum, etc. The specific structure of the radiopaque marker 3 in this embodiment is not particularly limited. Exemplarily, a circular radiopaque marker 3 is provided at the proximal end of the covered segment 1, and a strip-shaped radiopaque marker 3 is provided at the junction of the covered segment 1 and the bare segment 2.

[0078] The first framework of the embodiment of the present invention includes a plurality of first structural units arranged at axial intervals. Adjacent two first structural units have a first preset angle in the circumferential direction. The minimum surface distance between the first depression closest to the proximal end of the covered segment and the protrusion of the first structural unit adjacent to the axial proximal end is the largest among all the first surface distances in all configurations at the first preset angle, or the first surface distance between the first protrusion closest to the distal end of the covered segment and the depression of the first structural unit adjacent to the axial distal end is the largest among all the first surface distances in all configurations at the first preset angle. When the covered stent is compressed and loaded into the delivery device, the first structural units of the covered segment and the axially adjacent first structural units can reduce or even prevent the covering film around the protrusions and depressions from cracking or breaking through the above settings, thereby reducing the occurrence of covered stent failure. For example, for the covered stent used in TIPS, it can effectively prevent bile from entering the inner side of the stent and the liver tissue from squeezing into the inner side of the stent, avoiding the occurrence of early stenosis, occlusion, or mid- and long-term stenosis during the use of the covered stent, and improving the patency rate of the stent flow channel; for the covered stent used for aortic aneurysm, it can effectively prevent blood from flowing from the inside of the stent to the aortic aneurysm at the covered rupture, avoiding the continuous increase in aortic aneurysm pressure and possibly eventually leading to aortic rupture.

[0079] In other embodiments, the covered stent applied to other indications may include other structures in addition to the above-mentioned covered segment. Those skilled in the art can make further adjustments based on the covered segment of the embodiments of the present application in combination with the technologies in the art according to requirements. For example, adding a branch stent structure, adding a barbed structure, etc. These solutions are all within the protection scope of the present application.

[0080] In the above description, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0081] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a covered stent, characterized in that: The covered stent includes a covered section, and the covered section includes a first framework and a covering; The preparation method includes: providing a plurality of first structural units for forming the first framework, the first structural units having a plurality of protrusions facing the distal end and a plurality of depressions facing the proximal end, the protrusions and the depressions being arranged at intervals in sequence and connected end to end, and the plurality of first structural units being arranged axially at intervals; obtaining a first depression from among the plurality of depressions, the distance of the first depression from the proximal end of the covered section being less than the distances of the remaining depressions from the proximal end of the covered section; obtaining, from among the plurality of configurations formed by different circumferential positional relationships between the first structural unit and the first structural unit adjacent thereto axially at the proximal end, the configuration with the largest first surface distance as the configuration between the first structural unit and the first structural unit adjacent thereto axially at the proximal end, thereby obtaining the first framework, wherein all the protrusions of the first structural unit adjacent thereto axially at the proximal end are at the same distance from the distal end of the covered section, and in each of the configurations, there is a first surface distance between the first depression and the protrusions of the first structural unit adjacent thereto axially at the proximal end, and the first surface distance is the smallest of the surface distances between the first depression and all the protrusions of the first structural unit adjacent thereto axially at the proximal end; fixing the covering to the first framework to obtain the covered stent; or, The preparation method includes: providing a plurality of first structural units for forming the first framework, the first structural units having a plurality of protrusions facing the distal end and a plurality of depressions facing the proximal end, the protrusions and the depressions being arranged at intervals in sequence and connected end to end, and the plurality of first structural units being arranged axially at intervals; obtaining a first protrusion from among the plurality of protrusions, the distance of the first protrusion from the distal end of the covered section being less than the distances of the remaining protrusions from the distal end of the covered section; obtaining, from among the plurality of configurations formed by different circumferential positional relationships between the first structural unit and the first structural unit adjacent thereto axially at the distal end, the configuration with the largest first surface distance as the configuration between the first structural unit and the first structural unit adjacent thereto axially at the proximal end, thereby obtaining the first framework, wherein all the depressions of the first structural unit adjacent thereto axially at the distal end are at the same distance from the proximal end of the covered section, and in each of the configurations, there is a first surface distance between the first protrusion and the depressions of the first structural unit adjacent thereto axially at the distal end, and the first surface distance is the smallest of the surface distances between the first protrusion and all the depressions of the first structural unit adjacent thereto axially at the distal end; fixing the covering to the first framework to obtain the covered stent.

2. The method for preparing a covered stent according to claim 1, characterized in that: When there are a plurality of the first depressions, the first surface distance is the smallest of the surface distances between all the first depressions and all the protrusions of the first structural unit adjacent thereto axially at the proximal end; When there are a plurality of the first protrusions, the first surface distance is the smallest of the surface distances between all the first protrusions and all the depressions of the first structural unit adjacent thereto axially at the distal end.

3. The method for preparing a covered stent according to claim 1, characterized in that: The first structural unit includes N repeating structural units, and the N repeating structural units are sequentially connected in the circumferential direction. The head end of the first repeating structural unit is connected to the tail end of the Nth repeating structural unit, where N is a natural number greater than 1.

4. The method for preparing a covered stent according to claim 3, characterized in that: The number of the repeating structural units is four. In the proximal-to-distal direction, the structure of the repeating structural unit is "M"-shaped, or the structure of the repeating structural unit is "W"-shaped.

5. The method for preparing a covered stent according to claim 4, characterized in that: Further included is: providing a reinforcing film and covering the proximal part of the first recess, the distal part of the protrusion that is axially proximal to the first recess and has a first curved surface distance, and the film covering between the first recess and the protrusion; or, providing a reinforcing film and covering the distal part of the first protrusion, the proximal part of the recess that is axially distal to the first protrusion and has a first curved surface distance, and the film covering between the first protrusion and the recess.

6. The method for preparing a covered stent according to claim 5, characterized in that: When the first structural unit has a plurality of the first recesses, winding the reinforcing film in the circumferential direction around the proximal part of each first recess, the distal part of the protrusion that is axially proximal to the first recess and has a first curved surface distance, and the film covering between the first recess and the protrusion; or, When the first structural unit has a plurality of the first protrusions, winding the reinforcing film in the circumferential direction around the distal part of each first protrusion, the proximal part of the recess that is axially distal to the first protrusion and has a first curved surface distance, and the film covering between the first protrusion and the recess.

7. The method for preparing a covered stent according to claim 5 or 6, characterized in that: In the axial direction, the length of the reinforcing film covering the first protrusion part is greater than 0 mm and less than 2.5 mm, and / or the length of the reinforcing film covering the recess part that is axially distal to the first protrusion and has a first curved surface distance is greater than 0 mm and less than 2.5 mm; or, In the axial direction, the length of the reinforcing film covering the first recess part is greater than 0 mm and less than 2.5 mm, and / or the length of the reinforcing film covering the protrusion part that is axially distal to the first recess and has a first curved surface distance is greater than 0 mm and less than 2.5 mm.

8. The method for preparing a covered stent according to claim 5, characterized in that: The yield strength of the reinforcing film is greater than the yield strength of the film covering.

9. The method for preparing a covered stent according to claim 1, characterized in that: Providing a bare section at the distal end of the film covering section, and the radial dimension of the bare section is at least partially greater than the radial dimension of the film covering section.

10. The manufacturing method of the covered stent according to claim 1, wherein: The structure of the first structural unit is inconsistent with the axially adjacent first structural unit.

11. The manufacturing method of the covered stent according to claim 1, wherein: Obtaining the configuration with the largest first curved surface distance from 8 to 16 configurations formed by different circumferential position relationships between the first structural unit and the axially proximal adjacent first structural unit as the configuration between the first structural unit and the axially proximal adjacent first structural unit.

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