Covered stent

Abstract

A covered stent comprises a cut stent (100) and a covering membrane (200). The cut stent is defined to have a plurality of undulating struts (101); the undulating struts are sequentially arranged in the axial direction of the cut stent; any two adjacent undulating struts are connected by means of a plurality of connecting rods (102) distributed in the circumferential direction; the cut stent comprises a distal bare stent segment (110), a covered stent segment (120) and a proximal bare stent segment (130) sequentially arranged from the distal end to the proximal end in the axial direction of the cut stent; the covering membrane covers at least part of the outer surface of the covered stent segment; the covered stent segment is of an open-loop structure, and at least one of the distal bare stent segment and the proximal bare stent segment is of a closed-loop structure. The covered stent can ensure both flexibility and support, and thus has better applicability.

Description

Stent graft Technical Field

[0001] The present invention relates to the technical field of medical devices, and more particularly, to a cutting-type stent graft. Background Art

[0002] Cardiovascular and cerebrovascular diseases are major health issues, with aneurysms being the most common and a constant threat to human health. Covered stents, with their inherent advantage of immediate occlusion, are becoming increasingly widely used, particularly in lesions such as the thoracic aorta, abdominal aorta, heart valves, and carotid arteries. They can be used to isolate aneurysms and redirect blood flow through normal vessels.

[0003] Most of the current covered stents are fully covered, so that the stent is completely covered with a coating, or use a double-layer coating. The full coating method can easily affect the flexibility and elasticity of the stent, and the coating is also prone to rupture and other problems, reducing the effectiveness of the coating. Double-layer coating will significantly increase the thickness of the stent, which is not conducive to the delivery of the stent and entry into smaller blood vessels. In addition, if the release position is not appropriate, the existing covered stent is not easy to recover and readjust the position before release. In addition, the covered stent may also have problems such as proximal non-adherence to the wall or blocking branch blood vessels.

[0004] Therefore, for those skilled in the art, how to improve the performance of the stent graft is an urgent problem that needs to be solved.

[0005] It should be noted that the information disclosed in the background technology section of this application is only intended to deepen the understanding of the general background technology of this application, and should not be regarded as an admission or any form of implication that the information constitutes prior art already known to those skilled in the art. Summary of the Invention

[0006] The purpose of the present invention is to provide a coated stent, aiming to improve various aspects of the performance of the coated stent.

[0007] To achieve the above-mentioned purpose, the present invention provides a coated stent, which includes a cutting stent and a coating, the cutting stent is defined by a plurality of wave rods, the plurality of wave rods are arranged in sequence along the axial direction of the cutting stent, and any adjacent wave rods are connected by a plurality of circumferentially distributed connecting rods, the cutting stent includes a distal bare stent segment, a coated stent segment and a proximal bare stent segment which are arranged in sequence along its own axial direction from the distal end to the proximal end, the coating is coated on at least part of the outer surface of the coated stent segment, the coated stent segment is an open-loop structure, and at least one of the distal bare stent segment and the proximal bare stent segment is a closed-loop structure.

[0008] Preferably, several of the wave rods include first-type wave rods and second-type wave rods, the size of the first-type wave rods is larger than that of the second-type wave rods, the wave rods in the distal bare stent segment and the proximal bare stent segment are both composed of the second-type wave rods, and the wave rods in the coated stent segment are composed of the first-type wave rods and the second-type wave rods, and the ratio of the number of wave heads of the first-type wave rods to the number of wave heads of the second-type wave rods is 1:1.5.

[0009] Preferably, the first type of wave rod and the second type of wave rod in the coated stent segment are alternately distributed along the axial direction of the cutting stent, so that a first type of wave rod is provided every interval of a second type of wave rod, and the proximal end and the distal end of the coated stent segment are both the first type of wave rod.

[0010] Preferably, the number of the second-type wave rods in the distal bare stent segment is 2 to 10, and / or the number of the second-type wave rods in the proximal bare stent segment is 1 to 5.

[0011] Preferably, the number of wave heads of the first type of wave rod in the coated stent segment is 6 to 10, the number of wave heads of the second type of wave rod in the coated stent segment is 8 to 16, and the number of connecting rods connecting the adjacent first type of wave rod and second type of wave rod in the coated stent segment is 3 to 6, and they are evenly distributed along the circumference of the cutting stent.

[0012] Preferably, the number of wave heads of the first type wave rod in the coated stent segment is 8, the number of wave heads of the second type wave rod in the coated stent segment is 12, and adjacent first type wave rods and second type wave rods in the coated stent segment are connected by 4 connecting rods.

[0013] Preferably, in the expanded state, the length of the stent graft segment is 4 mm to 30 mm.

[0014] Preferably, the proximal end of the coating is arranged on the open-loop structure, and the distal end of the coating is arranged on the closed-loop structure.

[0015] Preferably, several of the wave rods include a first type of wave rod and a second type of wave rod, the size of the first type of wave rod is larger than the size of the second type of wave rod, the wave rods in the distal bare stent segment and the proximal bare stent segment are both composed of the second type of wave rod, the wave rod in the coated stent segment is composed of the first type of wave rod and the second type of wave rod, the proximal end of the coating is arranged on the first type of wave rod at the proximal end of the coated stent segment, the distal end of the coating is arranged on the second type of wave rod of the distal bare stent segment, and the distal bare stent segment is a closed-loop structure.

[0016] Preferably, the distal end of the coating is arranged on the second-to-last or third-to-last second-type wave rod of the distal bare stent segment counted from the distal end to the proximal end.

[0017] Preferably, the coated stent also includes a plurality of fixed membranes, all of which are arranged in the lumen of the cutting stent and adhere to the inner surface of the cutting stent, the proximal end and the distal end of the coating are respectively connected to a plurality of the fixed membranes, and the plurality of fixed membranes connected to either end of the coating are distributed along the circumference of the cutting stent, and each fixed membrane is not fixed to the wave rod it covers.

[0018] Preferably, the stent graft further has at least one of the following characteristics:

[0019] The distal bare stent segment is provided with a plurality of imaging points distributed along its circumference;

[0020] The proximal bare stent segment is provided with a plurality of imaging points distributed along its circumference;

[0021] At least one of the proximal end and the distal end of the stent graft segment is provided with a plurality of imaging points distributed along the circumference thereof.

[0022] Preferably, the distal bare stent segment and the proximal bare stent segment are both closed-loop structures.

[0023] Compared with the prior art, the stent graft provided by the present invention has at least the following advantages:

[0024] In the above-mentioned stent graft, the stability and support of the stent graft are improved by the closed-loop structure of at least one of the distal bare stent segment and the proximal bare stent segment, and the flexibility and wall-adherence of the stent graft at the grafting position are improved by the open-loop structure of the grafted stent segment, thereby enabling the grafted stent to take into account flexibility, anchoring and wall-adherence. In addition, because the graft only covers the outer surface of the grafted stent segment, forming a single-layer and partial graft, the influence of the graft on the cut stent can be reduced, ensuring the flexibility and effectiveness of the graft, and also without increasing the thickness of the stent, so that the grafted stent can be delivered and enter smaller blood vessels.

[0025] In the above-mentioned coated stent, the flexibility of the coated stent is further increased by the second type of wave rod, and the support of the coated stent is further increased by the first type of wave rod, so that the support and stability of both ends of the coated stent are better, and the flexibility and support of the coating position can be better taken into account.

[0026] In the above-mentioned stent graft, the proximal end of the graft is arranged on an open-loop structure, and the distal end of the graft is arranged on a closed-loop structure, which enables the distal end of the graft to be recovered and repositioned. In this way, the grafted stent of the present invention can further take into account the recovery performance and positioning performance on the basis of taking into account the flexibility, anchoring and wall adhesion.

[0027] In the above-mentioned covered stents, the number of second-type wave rods in the distal bare stent segment is 2 to 10, which is beneficial for recovering the covered stent using the distal bare stent segment after the distal end of the covered stent segment and the distal end of the coating are released, and then releasing the covered stent after readjusting the position, thereby ensuring the effectiveness and accuracy of isolating blood vessels and blood flow.

[0028] In the above-mentioned covered stents, the number of the second-type wave rods in the proximal bare stent segment is 1 to 5, which is beneficial for not blocking the branch blood vessels at the proximal end after the covered stent is fully released, thereby ensuring smooth blood flow in the branch blood vessels.

[0029] In the above-mentioned stent graft, the length of the stent graft segment is 4 mm to 30 mm. In this way, the stent graft can be used to isolate a variety of target objects such as aneurysms, ensuring its scope of application. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Those skilled in the art will appreciate that the accompanying drawings are provided for a better understanding of the present invention and do not constitute any limitation on the scope of the present invention.

[0031] FIG1 is a schematic structural diagram of a cutting bracket according to an embodiment of the present invention;

[0032] FIG2 is a schematic structural diagram of a stent graft according to an embodiment of the present invention;

[0033] FIG3 is a schematic diagram of the installation of a plurality of fixed membranes connected to the proximal end of the covering according to one embodiment of the present invention;

[0034] FIG4 is a schematic diagram of the installation of a plurality of fixed membranes connected to the distal end of the covering according to an embodiment of the present invention.

[0035] In the accompanying drawings: 100 - cutting stent; 101 - wave rod; 1011 - first type wave rod; 1012 - second type wave rod; 102 - connecting rod; 103 - developing point; 110 - distal bare stent segment; 120 - coated stent segment; 130 - proximal bare stent segment; 200 - coating; 300 - fixed membrane. DETAILED DESCRIPTION

[0036] In order to make the objects, advantages and features of the present invention clearer, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In addition, the structure shown in the drawings is often a part of the actual structure. In particular, the emphasis required to be shown in each drawing is different, and sometimes different proportions are used. As used in this specification, the singular forms "one", "an" and "the" include plural objects, unless the content clearly indicates otherwise. As used in this specification, the term "or" is generally used in a sense that includes "and / or", unless the content clearly indicates otherwise.

[0037] In this application document, "diameter" refers to "outer diameter", "axial" refers to the direction along the central axis of the stent graft, "circumferential" refers to the direction around the central axis of the stent graft, and "radial" refers to the direction perpendicular to the central axis of the stent graft, that is, the diameter direction. In this application document, "proximal end" refers to the end of the stent graft that is close to the surgical operator when it is delivered, and "distal end" refers to the end of the stent graft that is away from the surgical operator when it is delivered. The "length" and "diameter" described in this application document are the dimensions of the stent graft in the expanded state. In addition, "not exceeding" as described in this application document means less than or equal to. In this application document, "inside" refers to the side close to the inner surface of the stent graft; "outside" refers to the side close to the outer surface of the stent graft; the dimension along the direction from the inner surface to the outer surface of the stent graft is defined as the thickness of the stent graft.

[0038] The core idea of ​​the present invention is to provide a coated stent that aims to take into account various aspects of performance, especially thickness, flexibility, anchoring, wall adhesion, recovery performance, positioning performance, and transportation performance, so as to better apply the coated stent.

[0039] The coated stent provided by the present invention can be expanded by itself or with the help of external force, and the present invention has no special requirements for this.

[0040] The stent graft provided by the present invention has at least a contracted state and an expanded state, and is capable of switching between the two states. The stent graft is in the contracted state when being transported within a delivery system. In this contracted state, the stent graft is axially elongated, facilitating delivery and entry into small blood vessels. The stent graft is in the expanded state after being released from the delivery system. It should be understood that the expanded state includes the stent graft's naturally expanded state when not constrained by external forces, as well as the expanded state when constrained by external forces.

[0041] As will be appreciated by those skilled in the art, the stent graft provided by the present invention may be used to treat a variety of medical conditions, including but not limited to the treatment of aneurysms. Although the stent graft may be particularly helpful in treating aneurysms, it is not limited to such treatment.

[0042] The following description is given with reference to the accompanying drawings.

[0043] 1 and 2 , the coated stent provided by the present invention includes a cutting stent 100 and a coating 200. The cutting stent 100 is a three-dimensional mesh structure and is defined by a plurality of wave rods 101, which are annular and mostly sawtooth or sinusoidal. The plurality of wave rods 101 are arranged in sequence along the axial direction of the cutting stent 100, and any adjacent wave rods 101 are connected by a plurality of circumferentially distributed connecting rods 102, and each connecting rod 102 connects the crests and troughs of adjacent wave rods 101. The connecting rod 102 can support and reduce the deflection of the stent. Here, the crests or troughs on the same wave rod 101 are defined as wave heads. The cutting stent 100 is generally carved from a pipe, and its material is not limited. It is generally selected from materials with good elasticity such as stainless steel and nickel-titanium alloy, but it is not actually limited to this.

[0044] The coating 200 is coated on the outer surface of the cutting stent 100 and is used to immediately occlude the target object (e.g., a blood vessel, an aneurysm, etc.). In practice, the coating 200 is only coated on a portion of the outer surface of the cutting stent 100, achieving partial coating and single-sided coating. This partial coating and single-sided coating (i.e., single-layer coating) approach reduces the impact of the coating 200 on the cutting stent 100, ensures the flexibility of the coated stent and the effectiveness of the coating 200, and does not increase the thickness of the coated stent, allowing the coated stent to be delivered and inserted into smaller blood vessels.

[0045] In more detail, the cutting stent 100 includes a distal bare stent segment 110, a coated stent segment 120, and a proximal bare stent segment 130, which are arranged in sequence along its own axis from the distal end to the proximal end. The coating 200 is coated on at least a portion of the outer surface of the coated stent segment 120. The proximal bare stent segment 130 is basically not provided with a coating 200, while the proximal end of the distal bare stent segment 110 may be covered by the coating 200. Except for the proximal portion of the distal bare stent segment 110, the remaining portion is not provided with a coating 200. It should be noted that, in order to facilitate the recovery and fixation of the coating 200, in a preferred embodiment of the present invention, the distal end of the coating 200 extends to cover the proximal end of the distal bare stent segment 110.

[0046] Preferably, in the expanded state, the length of the stent graft segment 120 is 4 mm to 30 mm. In this way, the stent graft of the present invention can be used to isolate a plurality of target objects such as aneurysms, ensuring its scope of application.

[0047] Among them, at least one of the distal bare stent segment 110 and the proximal bare stent segment 130 is a closed-loop structure, and the coated stent segment 120 is an open-loop structure. The closed-loop structure means that the number of connecting rods 102 is the same as the number of wave heads on the wave rod 101 connected to the connecting rod 102. After the closed-loop structure is set, the stability and support of the coated stent are increased. Preferably, if the release position is inappropriate, the distal end of the coated stent can also be recovered. The open-loop structure means that the number of connecting rods 102 is less than the number of wave heads on the wave rod 101 connected to the connecting rod 102. After the open-loop structure is set, the bending flexibility of the coated stent at the coated position is increased, and the bending and wall adhesion performance of the coated stent is also increased, thereby preventing internal leakage. In some embodiments, the distal bare stent segment 110 and the proximal bare stent segment 130 are both closed-loop structures. In other embodiments, the distal bare stent segment 110 is an open-loop structure, and the proximal bare stent segment 130 is a closed-loop structure.

[0048] In some embodiments, the wave rods 101 on the cutting stent 100 may all be second-type wave rods 1012, which are small wave rods. The small wave rods are small in size and can improve the compliance of the coated stent.

[0049] Preferably, the plurality of struts 101 on the cutting stent 100 include first-type struts 1011 and second-type struts 1012. The first-type struts 1011 are large struts, and their dimensions are larger than those of the second-type struts 1012. Dimensions herein include wave height and wave width (i.e., strut width). The distance from peak to trough (i.e., wave height) in the first-type struts 1011 is greater than the distance from peak to trough (i.e., wave height) in the second-type struts 1012, and the width (i.e., strut width) of the first-type struts 1011 is greater than that of the second-type struts 1012. The first-type struts 1011 can enhance the support and anchoring performance of the coated stent.

[0050] In one embodiment, the struts 101 in the stent graft segment 120 are composed of first-type struts 1011 and second-type struts 1012, while both the distal bare stent segment 110 and the proximal bare stent segment 130 utilize second-type struts 1012. In other embodiments, the struts 101 in the stent graft segment 120 utilize second-type struts 1012. As in this embodiment, the struts 101 in the stent graft segment 120 are composed of first-type struts 1011 and second-type struts 1012, thereby achieving a balance between compliance and support at the graft site, resulting in improved performance.

[0051] Preferably, the first-type wave rods 1011 and the second-type wave rods 1012 in the coated stent segment 120 are alternately distributed along the axial direction of the cutting stent 100, that is, a first-type wave rod 1011 is arranged every second-type wave rod 1012, and the proximal end and the distal end of the coated stent segment 120 are both first-type wave rods 1011, so that the proximal end of the coated stent segment 120 is connected to the proximal bare stent segment 130 through the first-type wave rod 1011, and the distal end of the coated stent segment 120 is connected to the distal bare stent segment 110 through the first-type wave rod 1011.

[0052] The wave rod 101 in the distal bare stent segment 110 is composed of the second type of wave rod 1012, that is, all wave rods are used, and the distal bare stent segment 110 is preferably a closed-loop structure; in this way, on the basis of ensuring the support by the closed-loop structure of the distal bare stent segment 110, the wall adhesion performance of the distal bare stent segment 110 can be increased by the wave rod design, and at the same time, the distal end of the coated stent can be recovered and repositioned by the closed-loop wavelet design of the distal bare stent segment 110, and the branch blood vessels can be avoided after the distal end of the coated stent is released. It is understandable that during the release process of the coated stent, if the distal end of the coating 200 is not opened or released in place, the distal end of the coated stent can also be recovered by the closed-loop wavelet design of the distal bare stent segment 110.

[0053] All the wave rods 101 in the proximal bare stent segment 130 adopt the second type wave rod 1012, and the proximal bare stent segment 130 is preferably a closed-loop structure; in this way, the closed-loop wavelet design of the proximal bare stent segment 10 can provide more connection points with the delivery system, further increasing the stability of the coated stent.

[0054] Specifically, the ratio of the number of wave tips (defined as a) of the first type of wave rod 1011 to the number of wave tips (defined as b) of the second type of wave rod 1012 in the cutting stent 100 is 1:1.5. By satisfying this ratio, the stent graft of the present invention achieves optimal performance in all aspects.

[0055] Therefore, after the actual use of the coated stent of the present invention, the degree of freedom of the open-loop wave rod of the coated stent segment 120 can be used to improve the bending and wall-adhering performance of the coated stent segment to prevent internal leakage, and the large wave rod in the coated stent segment 120 can be used to ensure the support and anchoring force of the coated segment. At the same time, the small wave rod in the coated stent segment 120 can be used to improve the flexibility of the stent, and combined with the distal bare stent segment 110 and the proximal bare stent segment 130, the recyclable and repeatable positioning of the coated stent can be achieved.

[0056] The number (i.e., wave count) of the wave bars 101 (i.e., second-type wave bars 1012) of the distal bare stent segment 110 along the axial direction of the cutting stent 100 is preferably 2 to 10, and more preferably, 5 to 8. This facilitates the release of the distal ends of the covered stent segment 120 and the distal ends of the stent graft 200. The covered stent can then be retrieved using the distal bare stent segment 110 and released again after adjusting its position, ensuring effective and precise isolation of the blood vessel and blood flow.

[0057] The number (i.e., wave number) of the proximal bare stent segment 130 wave bars 101 (i.e., second-type wave bars 1012) along the axial direction of the cutting stent 100 is preferably 1 to 5, and more preferably 2 to 3. This ensures that after the covered stent is fully released, the branch vessels are not blocked, ensuring smooth blood flow in the branch vessels.

[0058] The number of wave heads of the first-type wave rods 1011 in the stent graft segment 120 can be 6 to 10, with a more preferred number being 8. The number of wave heads of the second-type wave rods 1012 in the stent graft segment 120 can be 8 to 16, with a more preferred number being 12. In a preferred embodiment, the number of wave heads of the first-type wave rods 1011 in the stent graft segment 120 is 8, the number of wave heads of the second-type wave rods 1012 in the stent graft segment 120 is 12, and adjacent first-type wave rods 1011 and second-type wave rods 1012 in the stent graft segment 120 are connected by four connecting rods 102, and the four connecting rods 102 are evenly distributed along the circumference of the cutting stent 100.

[0059] Preferably, the number of connecting rods 102 in the coated stent segment 120 that are connected to the adjacent first-type wave rods 1011 and second-type wave rods 1012 is 3 to 6. In the coated stent segment 120, the uniform arrangement of the connecting rods 102 can avoid the problem of excessive deformation due to open loops, thereby ensuring its support. The number of connecting rods 102 in the coated stent segment 120 that are connected to the adjacent first-type wave rods 1011 and second-type wave rods 1012 is generally half the number of wave heads of the first-type wave rods 1011, so as to take into account both support and flexibility. The number of wave rods 101 in the coated stent segment 120 can be determined according to the length of the target object to be isolated. Generally, the number of wave rods 101 in the coated stent segment 120 (total number) can be 4 to 20.

[0060] Preferably, in the expanded state, the length of the stent graft 200 is 7 to 30 mm, the length of the proximal bare stent segment 130 is 0.8 to 4 mm, and the length of the distal bare stent segment 110 is 0.8 to 8 mm. Thus, the stent graft is suitable for most patients or individuals.

[0061] Because the coating 200 constrains the coated stent segment 120 to a certain extent, the diameters of the distal bare stent segment 110 and the proximal bare stent segment 130 are typically larger than the diameter of the coated stent segment 120. Preferably, in the deployed state, the diameters of the distal bare stent segment 110 and the proximal bare stent segment 130 are 1.0 to 1.5 times the diameter of the coated stent segment 120. Furthermore, at least one of the distal bare stent segment 110 and the proximal bare stent segment 130 has a flared opening. This flared opening provides better anchoring of the distal and proximal ends of the stent graft after deployment.

[0062] Preferably, the proximal end of the coating 200 is disposed on an open-loop structure, and the distal end of the coating 200 is disposed on a closed-loop structure, so as to facilitate the recovery and repositioning of the distal end of the coated stent. Preferably, the proximal end of the coating 200 is disposed on the first-type wave rod 1011 at the proximal end of the coated stent segment 120, so as to provide a stronger supporting force through the first-type wave rod 1011; and the distal end of the coating 200 is preferably disposed on the second-type wave rod 1012 of the distal bare stent segment 110. More preferably, the distal end of the coating 200 is disposed on the penultimate, second-to-last, or third-to-last second-type wave rod 1012 of the distal bare stent segment 110, counting from the distal end to the proximal end, so as to facilitate the recovery of the distal end of the coated stent.

[0063] The proximal end and the distal end of the coating 200 can be directly sutured to the cutting stent 100 or without suture.

[0064] 3 and 4 , in one embodiment of the present invention, the coated stent further includes a plurality of fixed membranes 300, all of which are arranged in the lumen of the cutting stent 100 and adhered to the inner surface of the cutting stent 100, and then the proximal end and the distal end of the coating 200 are respectively connected to the plurality of fixed membranes 300, and the plurality of fixed membranes 300 connected to either end of the coating 200 are distributed along the circumference of the cutting stent 100, usually evenly distributed along the circumference. The coating 200 and the fixed membrane 300 can be connected by hot melt connection, glue bonding, suture connection or other connection methods, preferably by hot melt connection. During hot melt connection, the coating is not likely to cause deformation of the stent, which reduces the risk of deformation of the stent, and makes the reliability and stability of the stent better, and the performance better.

[0065] As shown in Figure 3, in this embodiment, multiple fixed membrane sheets 300 connected to the proximal end of the coating 200 are attached to the first-type wave rod 1011 at the nearest end of the coated stent segment 120. The first-type wave rod 1011 has a large supporting force and is easy to open and anchor, thereby making the proximal end of the coating 200 better adhere to the wall to prevent internal leakage.

[0066] As shown in Figure 4, in this embodiment, multiple fixed membranes 300 connected to the distal end of the coating 200 are adhered to the inner surface of the distal bare stent segment 110. Preferably, these fixed membranes 300 are arranged on the second-to-last to third-to-last second-type wave rods 1012 of the distal bare stent segment 110 counting from the distal end to the proximal end. This is beneficial for the distal end of the coated stent to be recovered and repositioned and then released when the distal end of the coated stent is opened and anchored.

[0067] The size of the fixed diaphragm 300 is very small, much smaller than the coating 200. Therefore, the fixed diaphragm 300 does not increase the thickness of the stent and can also minimize the impact on the cutting stent 100. The thickness of the fixed diaphragm 300 does not exceed the thickness of the coating 200. The fixed diaphragm 300 can be directly connected to the external coating 200 through the mesh on the cutting stent 100. When connected, the fixed diaphragm 300 is kept flat so that the edge of the fixed diaphragm 300 is completely integrated with the coating 200. This coating method will not significantly increase the thickness of the coated stent. Because the fixed diaphragm 300 is set in the lumen of the cutting stent 100, it does not affect the appearance of the coated stent and also improves the flexibility of the coated stent.

[0068] Preferably, each fixed diaphragm 300 is not fixed to the wave bar 101 covered by the fixed diaphragm 300, so that the fixed diaphragm 300 can move relative to the covered wave bar 101. In this way, the impact of the fixed diaphragm 300 and the covering film 200 on the cutting stent 100 can be reduced, and the problems such as wrinkles and cracks in the covering film 200 can be avoided, further ensuring the effectiveness of the covering film 200. Specifically in this embodiment, the fixed diaphragm 300 is connected to the covering film 200 by hot melt. The middle part of the fixed diaphragm 300 is not fixed to the covered wave bar 101, and the side part of the fixed diaphragm 300 is fixed to the covering film 200 by hot melt through the mesh. Therefore, do not hot melt near the wave bar 101 to avoid affecting the expansion and contraction of the stent.

[0069] The fixed diaphragm 300 can have various shapes, including but not limited to the rectangular shape shown in the figure, as long as the fixed diaphragm 300 can connect with the external covering 200, ensure connection strength, and do not affect the expansion and contraction of the cutting stent 100. Preferably, the fixed diaphragm 300 is rectangular for ease of processing and hot-melting. The size of the fixed diaphragm 300 is primarily determined by the dimensions of the wave bar 101. The width of the fixed diaphragm 300 is greater than the width or thickness of the wave bar 101, so that the fixed diaphragm 300 can be attached to the inner surface of the wave bar 101 and can extend beyond the wave bar 101 to connect with the covering 200.

[0070] Among the multiple fixed membranes 300 connected to either end of the coating 200, these fixed membranes 300 can be arranged with one or more peaks or troughs spaced apart, or can be arranged without peaks or troughs spaced apart (i.e., directly adjacent to each other), and the fixed membranes 300 and the fixed membranes 300 do not overlap, and are all independently arranged. Preferably, the multiple fixed membranes 300 connected to either end of the coating 200 are evenly distributed along the circumference of the cutting bracket 100, so that the coating 200 is evenly stressed and less prone to more wrinkles. There are no special requirements for the number of fixed membranes 300 connected to either end of the coating 200. On the premise of meeting the connection strength, the number of fixed membranes 300 is minimized to avoid increasing the thickness of the coating bracket. Optionally, 2 to 6 fixed membranes 300 are connected to either end of the coating 200.

[0071] The multiple fixed membranes 300 connected to either end of the covering 200 are distributed in sequence in the circumferential direction of the cutting stent 100, and these fixed membranes 300 can be aligned or staggered in the axial direction of the cutting stent 100. Here, axial alignment means that the multiple fixed membranes 300 are arranged on the same circumference. In this case, the multiple fixed membranes 300 can be arranged at the same position of the multiple wave bars 101 in the circumferential direction. Axial staggering means that the multiple fixed membranes 300 are arranged on different circumferences, so that the multiple fixed membranes 300 are arranged at different positions of the multiple wave bars 101 in the circumferential direction. However, preferably, the multiple fixed membranes 300 connected to either end of the covering 200 are aligned in the axial direction to avoid the risk of the covering 200 warping due to uneven ends, thereby reducing the risk of thrombosis.

[0072] The fixed diaphragm 300 is usually only provided on the rod section between adjacent wave crests and wave troughs at a certain position of the wave rod 101, and the rod section may be covered with one or more fixed diaphragms 300. The multiple fixed diaphragms 300 connected to any end of the coating 200 may be partially staggered or completely staggered. When axially staggered, the multiple fixed diaphragms 300 may have various geometric arrangement paths, such as zigzag, wavy, etc., which are not specifically limited. It should also be noted that, in addition to connecting the fixed diaphragms 300 at both axial ends of the coating 200, multiple fixed diaphragms 300 may be further connected at a certain position between the proximal end and the distal end of the coating 200 to better fix the coating 200.

[0073] It should also be understood that when the fixed membrane 300 is provided, the fixed membrane 300 can be blocked by the bent portion (i.e., the crest or trough) on the wave rod 101, thereby preventing the fixed membrane 300 from undergoing significant displacement and preventing the fixed membrane 300 from slipping off the covered wave rod 101 during stent stretching. Furthermore, the fixed membrane 300 is limited to the rod segment between two adjacent crests and troughs. This ensures that the membrane 200 does not undergo significant displacement during stent stretching, thereby preventing a significant change in the relative position of the membrane 200 and the cutting stent 100, thereby preventing excessive wrinkling of the membrane 200 from causing thrombosis.

[0074] The material of the fixed diaphragm 300 is the same as or different from the material of the covering film 200. The covering film 200 is made of a common polymer material. For example, the covering film 200 is made of expanded polytetrafluoroethylene (ePTFE), polyester (PET), polyurethane (TPU), polylactic acid (PLA) or other polymer materials. When the material of the fixed diaphragm 300 is the same as that of the covering film 200, the bonding strength between the fixed diaphragm 300 and the covering film 200 is better when hot-melted, while ensuring the hot-melt strength, the effectiveness of the fixed covering film 200 can be improved. In addition, after adding the fixed diaphragm 300, there is no need to add biological evaluation tests, which is convenient to use.

[0075] Preferably, a plurality of developing points 103 are provided on the cutting stent 100 to facilitate the positioning of the coating 200 and both ends of the stent, thereby more accurately releasing the coating 200 at the target position, such as at the neck of the aneurysm, to facilitate immediate occlusion of the aneurysm.

[0076] In some embodiments, multiple developing points 103 are provided on the distal bare stent segment 110. In some embodiments, multiple developing points 103 are provided on the proximal bare stent segment 130. In some embodiments, multiple developing points 103 are provided on at least one of the proximal and distal ends of the coated stent segment 120. The developing points 103 at corresponding positions are typically distributed along the circumference of the stent to facilitate determination of the circumferential adhesion of the coated stent. The developing points 103 can be developed under X-rays and can be implemented using developing springs, developing springs, or other structures, which are not limited in this application.

[0077] As shown in Figure 3, in this embodiment, a plurality of imaging points 103 are circumferentially arranged on a first-type wave bar 1011 at the proximal end of the coated stent segment 120. These imaging points 103 and the fixed membrane 300 are arranged on the same wave bar 101, alternating between the imaging points 103 and the fixed membrane 300 without interfering with each other. At this point, the proximal end of the graft 200 is fixed to the first-type wave bar 1011 at the proximal end of the coated stent segment 120, making it easier to locate the proximal end of the graft 200 using these imaging points 103.

[0078] Compared with the prior art, the stent graft of the present invention has at least the following advantages:

[0079] (1) The use of single-layer coating and partial coating reduces the impact of the coating on the stent, ensures the flexibility of the coated stent and the effectiveness of the coating, and does not increase the thickness of the stent, so that the coated stent can be delivered and enter smaller blood vessels.

[0080] (2) The open-loop structure design of the stent graft segment improves the bending and wall-adhering performance of the stent graft segment, thereby effectively preventing internal leakage.

[0081] (3) The first type of wave rods in the stent graft segment improve the support and anchoring properties of the stent graft, while the second type of wave rods in the stent graft segment improve the flexibility of the stent graft.

[0082] (4) On the basis of ensuring anchoring force and wall adhesion, the closed-loop wavelet of the distal bare stent segment is used to achieve the distal retrievability and repositioning of the stent graft, and to avoid blocking the branch vessels after the distal end of the stent graft is released. This enables the stent graft to have better recovery and positioning performance without blocking the branch vessels.

[0083] (5) The stability of the covered stent is further increased through the closed-loop wavelet of the proximal bare stent segment.

[0084] (6) When fixing the coating, sutures are not used, nor is a double-layer coating. Instead, a single coating is fixed to the cutting stent by multiple small fixing membranes, and all the fixing membranes are only set inside the cutting stent. This can minimize the increase in the thickness of the stent, provide more favorable conditions for the coated stent to enter the small delivery system to reach the more distal small blood vessels, and at the same time does not affect the appearance of the stent. It can also reduce the impact of the coating on the stent, and further improve the flexibility of the stent.

[0085] (7) The bending parts (peaks and troughs) on the wave rod are used to block the fixed diaphragm to prevent the fixed diaphragm from making a large displacement, so that the two ends of the membrane can only move within a relatively small area, which better fixes the relative position of the membrane on the wave rod and avoids excessive wrinkles of the membrane causing thrombosis.

[0086] (8) When the fixed membrane and the covering are connected by hot melt, the covering will not cause deformation of the stent, reducing the risk of stent deformation, making the stent more reliable and stable, and having better performance. Moreover, compared with the traditional covering method, the covering method of the fixed membrane is simpler and easier to mechanize, which facilitates the simplification of the manufacturing process of the covered stent and improves production efficiency.

[0087] The above description is only a description of the preferred embodiment of the present invention and does not limit the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure are within the scope of protection of the technical solution of the present invention.

Claims

1. A stent graft, characterized in that: It includes a cutting stent and a coating, the cutting stent is defined by a plurality of wave rods, the wave rods are arranged in sequence along the axial direction of the cutting stent, and any adjacent wave rods are connected by a plurality of circumferentially distributed connecting rods, the cutting stent includes a distal bare stent segment, a coated stent segment and a proximal bare stent segment which are arranged in sequence along its own axial direction from the distal end to the proximal end, the coating is coated on at least a portion of the outer surface of the coated stent segment, the coated stent segment is an open-loop structure, and at least one of the distal bare stent segment and the proximal bare stent segment is a closed-loop structure.

2. The stent graft according to claim 1, characterized in that: The wave rod includes a first type of wave rod and a second type of wave rod, the size of the first type of wave rod is larger than that of the second type of wave rod, the wave rods in the distal bare stent segment and the proximal bare stent segment are both composed of the second type of wave rod, the wave rod in the coated stent segment is composed of the first type of wave rod and the second type of wave rod, and the ratio of the number of wave heads of the first type of wave rod to the number of wave heads of the second type of wave rod is 1:1.

5.

3. The stent graft according to claim 2, characterized in that: The first-type wave rods and the second-type wave rods in the coated stent segment are alternately distributed along the axial direction of the cutting stent, so that a first-type wave rod is provided every interval of a second-type wave rod, and the proximal end and the distal end of the coated stent segment are both the first-type wave rods.

4. The stent graft according to claim 2, characterized in that: The number of the second-type wave rods in the distal bare stent segment is 2 to 10, and / or the number of the second-type wave rods in the proximal bare stent segment is 1 to 5.

5. The stent graft according to claim 2, characterized in that: The number of wave heads of the first type of wave rod in the coated stent segment is 6 to 10, the number of wave heads of the second type of wave rod in the coated stent segment is 8 to 16, and the number of connecting rods connected to adjacent first type of wave rods and second type of wave rods in the coated stent segment is 3 to 6, and is evenly distributed along the circumference of the cutting stent.

6. The stent graft according to claim 5, characterized in that: The number of wave heads of the first type of wave rod in the coated stent segment is 8, the number of wave heads of the second type of wave rod in the coated stent segment is 12, and adjacent first type of wave rods and second type of wave rods in the coated stent segment are connected by 4 connecting rods.

7. The stent graft according to claim 1 or 2, characterized in that: In the expanded state, the length of the stent graft segment is 4 mm to 30 mm.

8. The stent graft according to claim 1 or 2, characterized in that: The proximal end of the coating is arranged on the open-loop structure, and the distal end of the coating is arranged on the closed-loop structure.

9. The stent graft according to claim 1, characterized in that: The wave rod includes a first type of wave rod and a second type of wave rod, the size of the first type of wave rod is larger than that of the second type of wave rod, the wave rods in the distal bare stent segment and the proximal bare stent segment are both composed of the second type of wave rod, the wave rod in the coated stent segment is composed of the first type of wave rod and the second type of wave rod, the proximal end of the coating is arranged on the first type of wave rod at the proximal end of the coated stent segment, the distal end of the coating is arranged on the second type of wave rod of the distal bare stent segment, and the distal bare stent segment is a closed-loop structure.

10. The stent graft according to claim 9, characterized in that: The distal end of the coating is arranged on the second-to-last or third-to-last second-type wave rod of the distal bare stent segment counted from the distal end to the proximal end.

11. The stent graft according to claim 1 or 2, characterized in that: It also includes a plurality of fixed membranes, all of which are arranged in the lumen of the cutting stent and fit on the inner surface of the cutting stent, the proximal end and the distal end of the covering are respectively connected to the plurality of fixed membranes, the plurality of fixed membranes connected to any end of the covering are distributed along the circumference of the cutting stent, and each fixed membrane is not fixed to the wave rod it covers.

12. The stent graft according to claim 1 or 2, characterized in that: The stent graft also has at least one of the following features: The distal bare stent segment is provided with a plurality of imaging points distributed along its circumference; The proximal bare stent segment is provided with a plurality of imaging points distributed along its circumference; At least one of the proximal end and the distal end of the stent graft segment is provided with a plurality of developing points distributed along the circumference thereof.

13. The stent graft according to claim 1 or 2, characterized in that: The distal bare stent segment and the proximal bare stent segment are both closed-loop structures.

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