Covered stent

Abstract

The covered stent comprises a cutting stent and a covering film, the cutting stent is provided with a plurality of wave rods in a limited mode, the wave rods are sequentially arranged in the axial direction of the cutting stent, and any adjacent wave rods are connected through a plurality of connecting rods distributed in the circumferential direction; the cutting stent comprises a far-end bare stent section, a covered stent section and a near-end bare stent section which are sequentially arranged from the far end to the near end in the axial direction of the cutting stent, the covered film covers at least part of the outer surface of the covered stent section, the covered stent section is of an open-loop structure, and at least one of the far-end bare stent section and the near-end bare stent section is of a closed-loop structure. The flexibility and supporting performance of the covered stent can be considered, so that the covered stent can be better applied.

Description

Technical Field

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

[0002] Cardiovascular and cerebrovascular diseases are important diseases affecting human health, among which aneurysms are the most common, constantly endangering human health. Covered stents have become more and more widely used stents due to their innate advantage of immediate occlusion, especially applied to pathological locations such as the thoracic aorta, abdominal aorta, heart valves, carotid arteries, etc., and can be used to isolate aneurysms and guide blood to flow along the direction of normal blood vessels.

[0003] Most current covered stents are fully covered stents, which completely cover the stent with a film, or use a double-layer film. The fully covered method is likely to affect the flexibility and extensibility of the stent, and the film is also prone to problems such as rupture, reducing the effectiveness of the film. The double-layer film will greatly increase the thickness of the stent, which is not conducive to the delivery of the stent and entering smaller blood vessels. In addition, if the release position is inappropriate, the existing covered stents are not convenient to recycle, readjust the position and then release, and moreover, the covered stents may also have problems such as non-adherence of the proximal end or blocking of branch blood vessels.

[0004] Therefore, for those skilled in the art, how to improve the performance of covered stents is an urgent problem to be solved at present.

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

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

[0007] To achieve the above purpose, the present invention provides a covered stent, which includes a cutting stent and a film. The cutting stent defines a plurality of wave rods, and the plurality of wave rods are sequentially arranged along the axial direction of the cutting stent. Any adjacent wave rods are connected by a plurality of connecting rods distributed circumferentially. The cutting stent includes a distal bare stent section, a covered stent section, and a proximal bare stent section that are sequentially arranged along its own axial direction from the distal end to the proximal end. The film covers at least a part of the outer surface of the covered stent section. The covered stent section is an open-loop structure, and at least one of the distal bare stent section and the proximal bare stent section is a closed-loop structure.

[0008] 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 that of the second type of wave rod. The wave rods in the distal bare stent section and the proximal bare stent section are both composed of the second type of wave rod. The wave rods in the covered stent section are composed of the first type of wave rod and the second type of wave rod. 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.

[0009] Preferably, the first type of wave rod and the second type of wave rod in the covered stent section are alternately distributed along the axis of the cutting stent, so that one first type of wave rod is arranged every other second type of wave rod, and the first type of wave rod is located at both the nearest end and the farthest end of the covered stent section.

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

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

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

[0013] Preferably, in the deployed state, the length of the covered stent section is 4 mm to 30 mm.

[0014] Preferably, the proximal end of the covering film is arranged on the open-loop structure, and the distal end of the covering film 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 that of the second type of wave rod. The wave rods in the distal bare stent section and the proximal bare stent section are both composed of the second type of wave rod. The wave rods in the covered stent section are composed of the first type of wave rod and the second type of wave rod. The proximal end of the covering film is arranged on the first type of wave rod at the proximal end of the covered stent section, the distal end of the covering film is arranged on the second type of wave rod in the distal bare stent section, and the distal bare stent section is a closed-loop structure.

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

[0017] Preferably, the covered stent further includes a plurality of fixing diaphragms. All the fixing diaphragms are disposed in the lumen of the cutting stent and are attached to the inner surface of the cutting stent. The proximal and distal ends of the film covering are respectively connected to a plurality of the fixing diaphragms. The plurality of fixing diaphragms connected to either end of the film covering are circumferentially distributed along the cutting stent. Each fixing diaphragm is not fixed to the wave rod it covers.

[0018] Preferably, the covered stent further has at least one of the following features:

[0019] A plurality of developing points are provided on the distal bare stent segment and are circumferentially distributed along itself;

[0020] A plurality of developing points are provided on the proximal bare stent segment and are circumferentially distributed along itself;

[0021] At least one of the proximal and distal ends of the covered stent segment is provided with a plurality of developing points circumferentially distributed along itself.

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

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

[0024] In the above - mentioned covered stent, the stability and supportability of the covered stent are improved by the closed - loop structure of at least one of the distal bare stent segment and the proximal bare stent segment. Also, the flexibility and wall - adhering performance of the covered stent at the film - covering position are improved by the open - loop structure of the covered stent segment. Furthermore, the covered stent can take into account flexibility, anchoring property, and wall - adhering property. Also, since the film only covers the outer surface of the covered stent segment, forming a single - layer and partial film covering, it can reduce the influence of the film on the cutting stent, ensure the flexibility of the covered stent and the effectiveness of the film covering, and can also not increase the thickness of the stent, enabling the covered stent to be delivered and inserted into smaller blood vessels.

[0025] In the above - mentioned covered stent, the flexibility of the covered stent is further increased by the second - type wave rods, and the supportability of the covered stent is further increased by the first - type wave rods, making the supportability and stability at both ends of the covered stent better, and better taking into account the flexibility and supportability at the film - covering position.

[0026] In the above-mentioned covered stent, the proximal end of the covering film is arranged on the open-loop structure, and the distal end of the covering film is arranged on the closed-loop structure, so that the distal end of the covered stent can be retrieved and repositioned. In this way, the covered stent of the present invention can further take into account the retrieval performance and positioning performance on the basis of taking into account flexibility, anchoring property and wall attachment property.

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

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

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

[0030] Those of ordinary skill in the art will understand that the provided drawings are used to better understand the present invention and do not constitute any limitation to the scope of the present invention. Among them:

[0031] Figure 1 is a schematic structural diagram of a cutting stent provided by the present invention according to an embodiment;

[0032] Figure 2 is a schematic structural diagram of a covered stent provided by the present invention according to an embodiment;

[0033] Figure 3 is a schematic installation diagram of a plurality of fixing membranes connected to the proximal end of the covering film provided by the present invention according to an embodiment;

[0034] Figure 4 is a schematic installation diagram of a plurality of fixing membranes connected to the distal end of the covering film provided by the present invention according to an embodiment.

[0035] In the drawings:

[0036] 100 - cutting stent; 101 - wave rod; 1011 - first type of wave rod; 1012 - second type of wave rod; 102 - connecting rod; 103 - radiopaque marker; 110 - distal bare stent segment; 120 - covered stent segment; 130 - proximal bare stent segment; 200 - covering film; 300 - fixing membrane. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] To make the objectives, advantages, and features of the present invention clearer, the following further elaborates on the present invention in conjunction with the accompanying drawings and specific embodiments. It should be noted that the accompanying drawings are in highly simplified forms and not drawn to scale, merely for facilitating and clearly assisting in explaining the objectives of the embodiments of the present invention. In addition, the structures shown in the accompanying drawings are often part of the actual structures. In particular, the accompanying drawings need to show different focuses and sometimes use different scales. As used in this specification, the singular forms "a", "an", and "the" include plural objects unless the context clearly indicates otherwise. As used in this specification, the term "or" is generally used in the sense of including "and / or" unless the context clearly indicates otherwise.

[0038] In this application document, "diameter" refers to "outer diameter", "axial direction" refers to the direction along the central axis of the covered stent, "circumferential direction" refers to the direction around the central axis of the covered stent, and "radial direction" refers to the direction perpendicular to the central axis of the covered stent, that is, the diameter direction. In this application document, "proximal end" refers to the end of the covered stent that is close to the surgeon during delivery, and "distal end" refers to the end of the covered stent that is far from the surgeon during delivery. The "length" and "diameter" described in this application document are the dimensions of the covered stent in the deployed state. In addition, "not exceeding" described in this application document means less than or equal to. In this application document, "inner" refers to the side close to the inner surface of the covered stent; "outer" refers to the side close to the outer surface of the covered stent; the dimension from the inner surface to the outer surface of the covered stent is defined as the thickness of the covered stent.

[0039] The core idea of the present invention is to provide a covered stent, aiming to balance various performances, especially in terms of thickness, flexibility, anchoring property, wall attachment property, retrievability, positioning property, delivery property, etc., so as to better apply the covered stent.

[0040] The covered stent provided by the present invention can be self-expanded or expanded with the aid of external force, and there are no special requirements for this in the present invention.

[0041] The covered stent provided by the present invention has at least a contracted state and a deployed state, and can switch between the contracted state and the deployed state; when the covered stent is being delivered in the delivery system, it is in the contracted state. In the contracted state, the covered stent is axially elongated, which is beneficial for delivery and entering small blood vessels; after the covered stent is released from the delivery system, it is in the deployed state. It should be understood that the deployed state includes the natural deployed state of the covered stent without external force constraint and the deployed state with external force constraint.

[0042] As can be understood by those skilled in the art, the covered stent provided by the present invention can be used to treat various medical conditions, including but not limited to treating aneurysms. Although this covered stent may be particularly helpful for treating aneurysms, it is not limited to this treatment.

[0043] The following description is made with reference to the accompanying drawings.

[0044] Reference Figure 1 and Figure 2 According to the present invention, the covered stent includes a cutting stent 100 and a covering film 200. The cutting stent 100 is a three-dimensional network structure and defines a plurality of wave rods 101. The wave rods 101 are annular and mostly serrated 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 connecting rods 102 distributed circumferentially. Each connecting rod 102 connects the wave peaks and wave valleys of the adjacent wave rods 101. The connecting rods 102 can play a role in supporting and reducing the deflection of the stent. Herein, the wave peaks or wave valleys on the same wave rod 101 are defined as wave heads. The cutting stent 100 is generally engraved 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 limited thereto in practice.

[0045] The covering film 200 is coated on the outer surface of the cutting stent 100 and is used to immediately block a target object (such as a blood vessel, an aneurysm, etc.). Actually, the covering film 200 is only coated on a part of the outer surface of the cutting stent 100 to achieve local covering and single-sided covering. This way of local covering and single-sided covering (i.e., single-layer covering) reduces the influence of the covering film 200 on the cutting stent 100, ensures the flexibility of the covered stent and the effectiveness of the covering film 200, and can also not increase the thickness of the covered stent, enabling the covered stent to be transported and inserted into smaller blood vessels.

[0046] More specifically, the cutting stent 100 includes a distal bare stent segment 110, a covered stent segment 120, and a proximal bare stent segment 130 that are arranged in sequence along its own axial direction from the distal end to the proximal end. The covering film 200 is coated on at least a part of the outer surface of the covered stent segment 120. The proximal bare stent segment 130 is basically not provided with the covering film 200, and the proximal end of the distal bare stent segment 110 may be covered by the covering film 200. Except for the part near the proximal end of the distal bare stent segment 110 that is covered by the covering 200, the rest is not provided with the covering film 200. It should be noted that, in order to facilitate the recovery and fixation of the covering film 200, in a preferred embodiment of the present invention, the distal end of the covering film 200 extends to the proximal end of the distal bare stent segment 110 for covering.

[0047] Preferably, in the deployed state, the length of the covered stent segment 120 is 4 mm to 30 mm. In this way, the covered stent of the present invention can be used to isolate most target objects such as aneurysms and ensure its scope of application.

[0048] 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 covered 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 rods 101 connected by the connecting rods 102. After setting the closed-loop structure, the stability and support of the covered stent are increased. Preferably, when the release position is inappropriate, the distal end of the covered stent can also be recycled. The open-loop structure means that the number of connecting rods 102 is less than the number of wave heads on the wave rods 101 connected by the connecting rods 102. After setting the open-loop structure, the bending flexibility of the covered stent at the covered position is increased, and the bending wall attachment performance of the covered stent is also increased, thereby preventing endoleakage. In some embodiments, both the distal bare stent segment 110 and the proximal bare stent segment 130 are 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.

[0049] In some embodiments, all the wave rods 101 on the cutting stent 100 can be the second type of wave rod 1012, and the second type of wave rod 1012 is a small wave rod. The small wave rod has a small size, which can improve the flexibility of the covered stent.

[0050] Preferably, several wave rods 101 on the cutting stent 100 include the first type of wave rod 1011 and the second type of wave rod 1012. The first type of wave rod 1011 is a large wave rod, and the size of the first type of wave rod 1011 is larger than that of the second type of wave rod 1012. Here, the size includes the wave height and the wave width (i.e., the rod width). The distance from the wave peak to the wave valley in the first type of wave rod 1011 (i.e., the wave height) is greater than the distance from the wave peak to the wave valley in the second type of wave rod 1012 (i.e., the wave height), and the width of the first type of wave rod 1011 (i.e., the rod width) is greater than the width of the second type of wave rod 1012. The first type of wave rod 1011 can improve the support and anchoring performance of the covered stent.

[0051] In one embodiment, the wave rods 101 in the covered stent segment 120 are the first type of wave rod 1011 and the second type of wave rod 1012, and at the same time, both the distal bare stent segment 110 and the proximal bare stent segment 110 adopt the second type of wave rod 1012. In other embodiments, all the wave rods 101 in the covered stent segment 120 adopt the second type of wave rod 1012. As in this embodiment, the wave rods 101 in the covered stent segment 120 are composed of the first type of wave rod 1011 and the second type of wave rod 1012, so as to balance the flexibility and support at the covered position and have better performance.

[0052] Preferably, the first type of wave rods 1011 and the second type of wave rods 1012 in the covered stent segment 120 are alternately distributed along the axial direction of the cutting stent 100, that is, one first type of wave rod 1011 is arranged at an interval of one second type of wave rod 1012, and the proximalmost and distalmost ends of the covered stent segment 120 are both the first type of wave rods 1011, so that the proximal end of the covered stent segment 120 is connected to the proximal bare stent segment 130 through the first type of wave rod 1011, and the distal end of the covered stent segment 120 is connected to the distal bare stent segment 110 through the first type of wave rod 1011.

[0053] The wave rods 101 in the distal bare stent segment 110 are composed of the second type of wave rods 1012, that is, all small wave rods are used, and preferably the distal bare stent segment 110 is a closed-loop structure; in this way, on the basis of ensuring the support performance through the closed-loop structure of the distal bare stent segment 110, the wall attachment performance of the distal bare stent segment 110 can be increased through the small wave rod design, and at the same time, through the closed-loop small wave design of the distal bare stent segment 110, the distal end of the covered stent can be recovered and repositioned, and it can be avoided that the covered stent blocks the branch blood vessels after the distal end is released. It can be understood that during the release process of the covered stent, if the distal end of the film 200 is not opened or released in place, at this time, the distal end of the covered stent can also be recovered through the closed-loop small wave design of the distal bare stent segment 110.

[0054] All the wave rods 101 in the proximal bare stent segment 130 are the second type of wave rods 1012, and preferably the proximal bare stent segment 130 is a closed-loop structure; in this way, through the closed-loop small wave design of the proximal bare stent segment 10, more connection points for connecting with the delivery system can be provided, further increasing the stability of the covered stent.

[0055] Furthermore, the ratio of the number of wave heads (defined as a) of the first type of wave rods 1011 to the number of wave heads (defined as b) of the second type of wave rods 1012 in the cutting stent 100 is 1:1.5. By meeting the usage conditions of this ratio, all aspects of the performance of the covered stent of the present invention are in an optimal state.

[0056] Therefore, after actually using the covered stent of the present invention, the bending wall attachment performance of the covered stent segment 120 can be improved through the freedom degree of the open-loop wave rods of the covered stent segment 120 to prevent endoleakage, and the support performance and anchoring force of the covered film segment can be ensured through the large wave rods in the covered stent segment 120. At the same time, the flexibility of the stent can be improved through the small wave rods in the covered stent segment 120, and combined with the distal bare stent segment 110 and the proximal bare stent segment 130, the recoverability and repeated positioning of the covered stent can be realized.

[0057] The number (i.e., the number of waves) of the wave rods 101 (i.e., the second type of wave rods 1012) along the axis of the cutting stent 100 in the distal bare stent segment 110 is preferably 2 to 10, and more preferably, the number of waves is 5 to 8. In this way, after the distal end of the covered stent segment 120 and the distal end of the covering 200 are released, the covered stent can be recycled by using the distal bare stent segment 110, and after adjusting the position, the covered stent can be released again to ensure the effectiveness and accuracy of isolating blood vessels and blood flow.

[0058] The number (i.e., the number of waves) of the wave rods 101 (i.e., the second type of wave rods 1012) along the axis of the cutting stent 100 in the proximal bare stent segment 130 is preferably 1 to 5, and more preferably, the number of waves is 2 to 3. In this way, it does not block the branch blood vessels after the covered stent is completely released, ensuring the smooth blood flow of the branch blood vessels.

[0059] The number of wave heads of the first type of wave rods 1011 in the covered stent segment 120 can be 6 to 10, and the more suitable number is 8. The number of wave heads of the second type of wave rods 1012 in the covered stent segment 120 can be 8 to 16, and the more suitable number is 12. In a preferred embodiment, the number of wave heads of the first type of wave rods 1011 in the covered stent segment 120 is 8, the number of wave heads of the second type of wave rods 1012 in the covered stent segment 120 is 12, and the adjacent first type of wave rods 1011 and the second type of wave rods 1012 in the covered stent segment 120 are connected by 4 connecting rods 102, and the 4 connecting rods 102 are evenly distributed along the circumference of the cutting stent 100.

[0060] Preferably, the number of the connecting rods 102 connecting the adjacent first type of wave rods 1011 and the second type of wave rods 1012 in the covered stent segment 120 is 3 to 6. In the covered stent segment 120, due to the uniform arrangement of the connecting rods 102, the problem of excessive deformation due to the open loop can be avoided, ensuring its supportability. The number of the connecting rods 102 connecting the adjacent first type of wave rods 1011 and the second type of wave rods 1012 in the covered stent segment 120 is generally half of the number of wave heads of the first type of wave rods 1011, so as to balance the supportability and flexibility. The number of the wave rods 101 in the covered stent segment 120 can be determined according to the length of the target object to be isolated. Generally, the number (total number) of the wave rods 101 in the covered stent segment 120 can be 4 to 20.

[0061] Preferably, in the deployed state, the length of the covering 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 covered stent can be suitable for most patients or individuals.

[0062] Since the film covering 200 will, to a certain extent, restrict the covered stent segment 120, generally, the diameters of both the distal bare stent segment 110 and the proximal bare stent segment 130 are larger than the diameter of the covered 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 covered stent segment 120. Further, at least one of the distal bare stent segment 110 and the proximal bare stent segment 130 is a flared opening. After setting the flared opening, the distal and proximal ends can play a better anchoring role after the covered stent is opened.

[0063] Preferably, the proximal end of the film covering 200 is arranged on the open-loop structure, and the distal end of the film covering 200 is arranged on the closed-loop structure. In this way, it is convenient to realize the retrievability and repositioning of the distal end of the covered stent. Preferably, the proximal end of the film covering 200 is arranged on the first type of wave rod 1011 at the proximal end of the covered stent segment 120 to provide strong support force through the first type of wave rod 1011; while the distal end of the film covering 200 is preferably arranged on the second type of wave rod 1012 of the distal bare stent segment 110. More preferably, the distal end of the film covering 200 is arranged on the second type of wave rod 1012 which is the last, the second last or the third last one counted from the distal end to the proximal end on the distal bare stent segment 110 to facilitate the retrievability of the distal end of the covered stent.

[0064] The proximal and distal ends of the film covering 200 can be directly sutured to the cutting stent 100 or not in a suturing manner.

[0065] Reference Figure 3 and Figure 4 In an embodiment of the present invention, the covered stent further includes a plurality of fixing membrane sheets 300. All the fixing membrane sheets 300 are arranged in the lumen of the cutting stent 100 and are attached to the inner surface of the cutting stent 100. Furthermore, the proximal and distal ends of the film covering 200 are respectively connected to a plurality of fixing membrane sheets 300. The plurality of fixing membrane sheets 300 connected to either end of the film covering 200 are distributed circumferentially along the cutting stent 100, usually evenly distributed circumferentially. The film covering 200 and the fixing membrane sheets 300 can be connected by hot melting, glue bonding, suturing or other connection methods, and preferably by hot melting. When connected by hot melting, it is not easy to cause stent deformation due to the film covering, reducing the risk of stent deformation, making the reliability and stability of the stent better and the performance more excellent.

[0066] As Figure 3 shown, in this embodiment, the plurality of fixing membrane sheets 300 connected to the proximal end of the film covering 200 are attached to the first type of wave rod 1011 at the nearest end of the covered stent segment 120. The first type of wave rod 1011 has a large support force and is easy to open and anchor, so that the proximal end of the film covering 200 adheres to the wall better and prevents endoleakage.

[0067] As Figure 4As shown, in this embodiment, a plurality of fixing diaphragms 300 connected to the distal end of the film covering 200 are attached to the inner surface of the distal bare stent segment 110. Preferably, these fixing diaphragms 300 are arranged on the second to the third second type of wave rods 1012 counted from the distal end to the proximal end of the distal bare stent segment 110, which is conducive to recovering and repositioning the distal end of the covered stent and then releasing it when the distal end of the covered stent is opened and anchored.

[0068] The size of the fixing diaphragm 300 is very small, much smaller than that of the film covering 200. Therefore, the fixing diaphragm 300 does not increase the thickness of the stent and can also avoid affecting the cutting stent 100 to the greatest extent. The thickness of the fixing diaphragm 300 does not exceed the thickness of the film covering 200. The fixing diaphragm 300 can be directly connected to the external film covering 200 through the mesh holes on the cutting stent 100. When connecting, keep the fixing diaphragm 300 flat so that the edge of the fixing diaphragm 300 is completely fused with the film covering 200. This film covering method does not significantly increase the thickness of the covered stent, and because the fixing diaphragm 300 is arranged in the lumen of the cutting stent 100, it does not affect the appearance of the covered stent, and also improves the flexibility of the covered stent.

[0069] Preferably, each fixing diaphragm 300 is not fixed to the wave rod 101 covered by the fixing diaphragm 300, so that the fixing diaphragm 300 can move relative to the covered wave rod 101. In this way, the influence of the fixing diaphragm 300 and the film covering 200 on the cutting stent 100 can be reduced, and problems such as wrinkles and ruptures of the film covering 200 can be avoided, further ensuring the effectiveness of the film covering 200. Specifically in this embodiment, the fixing diaphragm 300 is heat-melt connected to the film covering 200. The middle part of the fixing diaphragm 300 is not fixed to the covered wave rod 101, and the side part of the fixing diaphragm 300 is heat-melt fixed to the film covering 200 through the mesh holes. Therefore, do not heat-melt near the wave rod 101 to avoid affecting the expansion and contraction of the stent.

[0070] The fixing diaphragm 300 can have various shapes, including but not limited to the illustrated rectangle, as long as the fixing diaphragm 300 can be connected to the external film covering 200, ensure the connection strength, and does not affect the expansion and contraction of the cutting stent 100. Preferably, the fixing diaphragm 300 is rectangular, which is convenient for processing and heat melting. The size of the fixing diaphragm 300 is mainly set according to the size of the wave rod 101. The width of the fixing diaphragm 300 is greater than the width or thickness of the wave rod 101, so that after the fixing diaphragm 300 is attached to the inner surface of the wave rod 101, it can still extend beyond the connection between the wave rod 101 and the film covering 200.

[0071] 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.

[0072] The multiple fixed diaphragms 300 connected to either end of the coating 200 are sequentially distributed in the circumferential direction of the cutting stent 100, and these fixed diaphragms 300 can be aligned or staggered in the axial direction of the cutting stent 100. Here, axial alignment means that the multiple fixed diaphragms 300 are arranged on the same circumference. In this case, the multiple fixed diaphragms 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 diaphragms 300 are arranged on different circumferences, so that the multiple fixed diaphragms 300 are arranged at different positions of the multiple wave bars 101 in the circumferential direction. However, preferably, the multiple fixed diaphragms 300 connected to either end of the coating 200 are aligned in the axial direction to avoid the risk of the coating 200 warping due to uneven ends, thereby reducing the risk of thrombosis.

[0073] The fixed diaphragm 300 is usually only arranged 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.

[0074] It should also be understood that when setting the fixed diaphragm 300, the bending part (i.e., the wave crest or wave trough) on the wave rod 101 can block the fixed diaphragm 300, preventing the fixed diaphragm 300 from having a large displacement, and not causing the fixed diaphragm 300 to slip off the covered wave rod 101 during the stretching of the stent, and enabling the fixed diaphragm 300 to move only on the rod section between two adjacent wave crests and wave troughs. Thus, it can be ensured that the covered film 200 does not have a large displacement during the stretching of the stent, and further, the relative position between the covered film 200 and the cutting stent 100 does not change significantly, thereby avoiding excessive folding of the covered film 200 and causing thrombosis.

[0075] The material of the fixed diaphragm 300 is the same as or different from that of the covered film 200. The covered film 200 is made of common polymer materials. For example, the covered film 200 is prepared from 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 covered film 200, the bonding strength during hot melting of the fixed diaphragm 300 and the covered film 200 is more excellent. While ensuring the hot melting strength, the effectiveness of fixing the covered film 200 can be improved. In addition, after adding the fixed diaphragm 300, there is no need to increase the biological evaluation test, which is convenient to use.

[0076] Preferably, a plurality of radiopaque markers 103 are provided on the cutting stent 100, which is convenient for positioning the covered film 200 and the positions at both ends of the stent, and further for more accurately releasing the covered film 200 at the target position, such as releasing it at the aneurysm neck opening, providing convenience for immediately occluding the aneurysm.

[0077] In some embodiments, a plurality of radiopaque markers 103 are provided on the distal bare stent segment 110. In some embodiments, a plurality of radiopaque markers 103 are provided on the proximal bare stent segment 130. In some embodiments, at least one of the proximal end and the distal end of the covered stent segment 120 is provided with a plurality of radiopaque markers 103. The radiopaque markers 103 at corresponding positions are generally distributed circumferentially along the stent to judge the circumferential wall attachment situation of the covered stent. The radiopaque markers 103 can be visualized under X-ray, and can be realized by using radiopaque springs, radiopaque springs or other structures. The present application is not limited thereto.

[0078] As Figure 3 shown, in this embodiment, a plurality of radiopaque markers 103 are provided circumferentially on the first type of wave rod 1011 at the proximal most end of the covered stent segment 120. These radiopaque markers 103 and the fixed diaphragm 300 are arranged on the same wave rod 101, and the radiopaque markers 103 and the fixed diaphragm 300 are arranged alternately without interfering with each other. At this time, the proximal end of the covered film 200 is fixed to the first type of wave rod 1011 at the proximal most end of the covered stent segment 120, which is convenient for positioning the proximal end of the covered film 200 through these radiopaque markers 103.

[0079] Compared with the prior art, the covered stent of the present invention has at least the following advantages:

[0080] (1) By adopting a single-layer film covering and partial film covering, the influence of the film covering on the stent is reduced, the flexibility of the covered stent and the effectiveness of the film covering are ensured, and the thickness of the stent is not increased, enabling the covered stent to be delivered and inserted into smaller blood vessels.

[0081] (2) Through the open-loop structure design of the covered stent section, the bending and wall-adhering performance of the covered section of the stent is improved, thereby effectively preventing endoleakage.

[0082] (3) The support and anchoring properties of the covered stent are improved by the first type of wave rods in the covered stent section, while the flexibility of the covered stent is improved by the second type of wave rods in the covered stent section.

[0083] (4) On the basis of ensuring the anchoring force and wall-adhering property, the distal end of the covered stent can be retrieved and repositioned through the closed-loop small waves of the distal bare stent section, and it can be avoided that the covered stent blocks the branch blood vessels after the distal end is released. This makes the covered stent also have good retrieval performance and positioning performance, and will not block the branch blood vessels.

[0084] (5) The stability of the covered stent is further increased through the closed-loop small waves of the proximal bare stent section.

[0085] (6) When fixing the film covering, instead of using suture stitching or double-layer film covering, a single film covering is fixed on the cutting stent through multiple small fixing patches, and all the fixing patches are only arranged inside the cutting stent, which can maximize the avoidance of increasing the thickness of the stent, provides more favorable conditions for the covered stent to enter a small delivery system and reach smaller blood vessels at a farther end, does not affect the appearance of the stent, can also reduce the influence of the film covering on the stent, and further improves the flexibility of the stent.

[0086] (7) The bending parts (peaks and valleys) on the wave rods are used to block the fixing patches, avoiding large displacements of the fixing patches, so that the two ends of the film covering can only move within a relatively small area, preferably fixing the relative position of the film covering on the wave rods, and avoiding excessive wrinkles of the film covering from causing thrombosis.

[0087] (8) When the fixing patches and the film covering are connected by hot melting, the stent will not be deformed due to the film covering, reducing the risk of stent deformation, making the stent more reliable and stable, and having better performance. Moreover, compared with the traditional film covering method, the film covering method with fixing patches is simpler, easier to operate mechanically, convenient for simplifying the manufacturing process of the covered stent, and improving production efficiency.

[0088] The above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention in any way. Any changes and modifications made by those of ordinary skill in the art of the present invention based on the above disclosure fall within the protection scope of the technical solution of the present invention.

Claims

1. A covered stent, characterized in that, it includes a cutting stent and a covering film. The cutting stent defines a plurality of wave rods, and the plurality of wave rods are arranged in sequence along the axial direction of the cutting stent. Any adjacent wave rods are connected by a plurality of connecting rods distributed circumferentially. The cutting stent includes a distal bare stent section, a covered stent section, and a proximal bare stent section arranged in sequence along its own axial direction from the distal end to the proximal end. The covering film covers at least a part of the outer surface of the covered stent section. The covered stent section is an open-loop structure, and at least one of the distal bare stent section and the proximal bare stent section is a closed-loop structure.

2. The covered stent according to claim 1, characterized in that, the plurality of 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 that of the second type of wave rod. The wave rods in the distal bare stent section and the proximal bare stent section are all composed of the second type of wave rod. The wave rods in the covered stent section are composed of the first type of wave rod and the second type of wave rod. 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 covered stent according to claim 2, characterized in that, the first type of wave rod and the second type of wave rod in the covered stent section are distributed alternately along the axial direction of the cutting stent, so that one first type of wave rod is arranged at every other second type of wave rod, and the nearest end and the farthest end of the covered stent section are both the first type of wave rod.

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

5. The covered stent according to claim 2, characterized in that, the number of wave heads of the first type of wave rod in the covered stent section is 6 to 10, the number of wave heads of the second type of wave rod in the covered stent section is 8 to 16, and the number of the connecting rods connecting the adjacent first type of wave rod and the second type of wave rod in the covered stent section is 3 to 6 and is evenly distributed along the circumferential direction of the cutting stent.

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

7. The covered stent according to claim 1 or 2, characterized in that, in the deployed state, the length of the covered stent section is 4 mm to 30 mm.

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

9. The covered stent according to claim 1 or 2, characterized in that, Some 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 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 rods in the covered stent segment are composed of the first type of wave rod and the second type of wave rod. The proximal end of the covering film is arranged on the first type of wave rod at the proximal end of the covered stent segment, and the distal end of the covering film is arranged on the second type of wave rod in the distal bare stent segment. And the distal bare stent segment is a closed-loop structure.

10. The covered stent according to claim 9, wherein, the distal end of the covering film is arranged on the second-to-last or third-to-last second type of wave rod counted from the distal end to the proximal end of the distal bare stent segment.

11. The covered stent according to claim 1 or 2, wherein, it further includes a plurality of fixing membranes. All the fixing membranes are arranged in the lumen of the cutting stent and are attached to the inner surface of the cutting stent. The proximal and distal ends of the covering film are respectively connected to a plurality of the fixing membranes. The plurality of fixing membranes connected to either end of the covering film are distributed circumferentially along the cutting stent. Each fixing membrane is not fixed to the wave rod it covers.

12. The covered stent according to claim 1 or 2, wherein, the covered stent further has at least one of the following features: a plurality of radiopaque points are arranged on the distal bare stent segment and are distributed circumferentially along itself; a plurality of radiopaque points are arranged on the proximal bare stent segment and are distributed circumferentially along itself; a plurality of radiopaque points are arranged on at least one of the proximal and distal ends of the covered stent segment and are distributed circumferentially along itself.

13. The covered stent according to claim 1 or 2, wherein, both the distal bare stent segment and the proximal bare stent segment are closed-loop structures.

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