Medical film covering device

Abstract

The invention provides a medical film covering device which comprises a support body, a film and a plurality of membranes, the membranes are attached to the inner surface of the support body, the membranes cover at least part of the outer surface of the support body, and the two ends of each membrane are connected with the multiple membranes distributed in the circumferential direction of the support body respectively, so that combination of the membranes and the support body is achieved, and the membrane covering effect is improved. The thickness of the stent is prevented from being increased, and the flexibility and appearance of the stent are not affected.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and more particularly, to a medical film covering device. Background Art

[0002] Cardiovascular and cerebrovascular diseases are important diseases affecting human health, among which aneurysms are the most common, constantly endangering human health. Due to its congenital advantage of being able to block, the covered stent has become a more and more widely used stent, especially applied to pathological positions such as the thoracic aorta, abdominal aorta, heart valve, carotid artery, etc., to isolate aneurysms and guide blood to flow along the direction of normal blood vessels. At present, most covered stents use the method of sewing to combine the film with the stent, which undoubtedly increases the thickness of the stent, and at the same time, the exposed thread heads also affect the appearance. Another method is to set films both inside and outside the stent, so that the inner and outer double-layer films are combined with the stent, which also increases the thickness of the stent, making it more difficult for the stent to enter smaller blood vessels. In particular, the inner and outer double-layer films are prone to binding the stent and making the stent lose its flexibility.

[0003] Therefore, for those skilled in the art, how to design a medical film covering device that does not increase the thickness of the stent and does not affect the flexibility of the stent is a technical problem that needs to be solved urgently at present.

[0004] 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

[0005] The purpose of the present invention is to provide a medical film covering device, which can realize the combination of the film and the stent without increasing the thickness of the stent and without affecting the flexibility of the stent.

[0006] To achieve the above purpose, the present invention provides a medical film covering device, including a stent body, a film and film pieces. The number of the film pieces is multiple, and all the film pieces are attached to the inner surface of the stent body. The film covers at least part of the outer surface of the stent body, and both ends of the film are respectively connected to a plurality of the film pieces distributed along the circumferential direction of the stent body.

[0007] Optionally, the stent body includes a plurality of grid bars, and the plurality of grid bars intersect with each other to form grids and intersections. Each film piece covers the grid bars between two adjacent intersections, and each film piece is not fixed to the grid bars covering the film piece.

[0008] Optionally, during the axial stretching of the medical film-covered device, each of the diaphragms can be limited by the corresponding crossing part, so that each diaphragm can only slide on the grid bars between two adjacent crossing parts it covers.

[0009] Optionally, the film is thermally fused to the diaphragms. Each diaphragm is provided with a non-thermally fused area and a thermally fused area. The thermally fused area is located at the edge of the diaphragm. The non-thermally fused area is in contact with the grid bars, and the thermally fused area is thermally fused to the film.

[0010] Optionally, a plurality of the diaphragms connected to any one end of the film are arranged at intervals of one or more grids in the circumferential direction of the stent body, or a plurality of the diaphragms connected to any one end of the film are arranged on each grid in the circumferential direction of the stent body.

[0011] Optionally, a plurality of the diaphragms connected to any one end of the film are aligned or staggered in the axial direction of the stent body.

[0012] Optionally, the same diaphragm covers one or more grid bars.

[0013] Optionally, the material of the film is the same as or different from the material of the diaphragms, and the thickness of the diaphragms does not exceed the thickness of the film.

[0014] Optionally, the length of the diaphragm is 0.2 mm to 5.0 mm, and the width of the diaphragm is 0.2 mm to 5.0 mm.

[0015] Optionally, wrinkles are formed after the film covers the stent body.

[0016] Optionally, the stent body is a braided stent or a cut stent.

[0017] Optionally, the stent body includes a plurality of stent segments. The plurality of stent segments include a distal bare stent segment, a film-covered stent segment, and a proximal bare stent segment that are sequentially connected axially from the distal end to the proximal end. The film covers the entire outer surface of the film-covered stent segment.

[0018] Optionally, the stent body is a cut stent, the film-covered 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.

[0019] Optionally, a predetermined part between the proximal end and the distal end of the film is connected to a plurality of other diaphragms.

[0020] Compared with the prior art, the medical film-covered device provided by the present invention has the following advantages:

[0021] In the above medical film covering device, neither suture nor double-layer film covering is adopted. Instead, a single-layer film is fixed on the stent body through multiple film pieces, and all the film pieces are only arranged in the inner cavity of the stent body and attached to the inner surface of the stent body. In this way, the combination of the film and the stent body can be realized, and at the same time, the thickness increase of the whole device can be maximally avoided without affecting the appearance, and the influence of the film covering on the stent body can also be reduced, improving the flexibility of the device. Further, when each film piece only covers the grid bars between two adjacent intersections and is not fixed to the grid bars covering the film piece, the influence of the film piece and the film on the stent body can be further reduced. In particular, the influence on the sliding of the braided wires can be reduced, the risk of stent deformation can be avoided, and the risk of film piece detachment can also be reduced. Further, during the axial stretching process of the medical film covering device, each film piece can be limited by the corresponding intersection so that the film piece can only slide on the grid bars between two adjacent intersections. In this way, a large displacement of the film relative to the stent body can be avoided, and the position of the film can be better fixed. It can also prevent the film from gathering and wrinkling towards the center line of the stent due to the expansion and contraction of the stent body, thereby avoiding excessive film wrinkling and causing thrombosis. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 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:

[0023] Figure 1 is a schematic diagram of the overall structure of the medical film covering device based on a braided stent in a preferred embodiment of the present invention;

[0024] Figure 2 is a schematic diagram of a partial structure of the medical film covering device based on a braided stent in a preferred embodiment of the present invention, in which the film and the stent body are joined by connecting the film through multiple film pieces;

[0025] Figure 3 is a schematic diagram of a partial structure of the medical film covering device based on a braided stent in a preferred embodiment of the present invention, in which the film is positioned by a visualization structure. The vertical line L represents the proximal edge of the film, and the part to the left of the proximal edge is the film;

[0026] Figure 4 is a schematic diagram of the structure of the cutting stent in a preferred embodiment of the present invention;

[0027] Figure 5 is a schematic diagram of the overall structure of the medical film covering device based on a cutting stent in a preferred embodiment of the present invention;

[0028] Figure 6 is a schematic diagram of the installation of multiple film pieces connected to the proximal end of the film covering in the medical film covering device based on a cutting stent in a preferred embodiment of the present invention;

[0029] Figure 7Schematic diagram of the installation of multiple diaphragm pieces connected to the distal end of the medical film in the medical film-covered device based on the cutting stent in the preferred embodiment of the present invention. Detailed implementation mode

[0030] To make the objectives, advantages and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the accompanying drawings are all in a very simplified form and are not drawn to scale, only for the purpose of 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 emphases and sometimes different scales are used. 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, and "several" means an indefinite quantity.

[0031] In this application, "diameter" refers to "outer diameter", "axial direction" refers to the axial direction of the medical film-covered device, "circumferential direction" refers to the direction around the axis of the medical film-covered device, and "radial direction" refers to the direction perpendicular to the axis of the medical film-covered device, that is, the diameter direction. In this application, "proximal end" refers to the end of the medical film-covered device close to the operator during delivery; "distal end" refers to the end of the medical film-covered device far from the operator during delivery. The "length" and "diameter" described in this article are the dimensions of the medical film-covered device in the deployed and expanded state.

[0032] The objective of the present invention is to provide a medical film-covered device, aiming to achieve the combination of the film and the stent without using the suture method, thereby avoiding increasing the thickness of the stent and not affecting the flexibility and appearance of the stent.

[0033] The medical film-covered device provided by the present invention can be used as a film-covered stent to achieve the treatment of related diseases. The medical film-covered device described in the present invention can be used to treat a variety of medical diseases, including but not limited to treating aneurysms. Although the medical film-covered device may be particularly helpful for treating aneurysms, it is not limited to this treatment.

[0034] The following is described with reference to the accompanying drawings.

[0035] First, refer to Figures 1 to 7 , the medical film-covered device provided by the embodiment of the present invention includes a stent body 100 and a film 200. The stent body 100 is in a net tubular shape. Refer to Figures 1 to 3 , in one implementation mode of the present invention, the stent body 100 is a braided stent. Refer to Figures 4 to 7 , in another implementation mode of the present invention, the stent body 100 is a cutting stent.

[0036] Whether it is a cutting stent or a braided stent, the stent body 100 includes a plurality of grid bars 101, and the plurality of grid bars 101 intersect to form a grid 102 and an intersection part 103. It should be understood that when the stent body 100 is a braided stent, the braided section is the grid bar 101; when the stent body 100 is a cutting stent, the cutting stent bars constitute the grid bar 101.

[0037] In actual use, the medical film covering device has a folded and contracted state and an unfolded and expanded state, and can be switched between the folded and contracted state and the unfolded and expanded state. Generally, when the medical film covering device is delivered through a delivery system, it is in the folded and contracted state. In the folded and contracted state, the medical film covering device is axially stretched, making its radial dimension smaller for easy delivery; after the medical film covering device is released from the delivery system, it is converted into the unfolded and expanded state, which is convenient for anchoring and isolating blood vessels and blood flow after unfolding and expansion. However, when the medical film covering device has no external force restraint, it is also in the unfolded and expanded state, and this unfolded and expanded state is the natural state.

[0038] The material of the stent body 100 can be selected from one or a combination of cobalt-based alloys, stainless steels, nickel-titanium alloys, platinum alloys, iridium alloys, bioactive ceramics, and carbon, and can also be selected from composite materials of these materials, but this is not limited in reality. The stent body 100 can expand and deploy autonomously or with the aid of external force, and this application does not limit this.

[0039] The film 200 is made of common polymer materials. For example, the film 200 is prepared using expanded polytetrafluoroethylene (ePTFE), polyester (PET), polyurethane (TPU), polylactic acid (PLA), or other polymer materials. The film 200 needs to cover at least part of the outer surface of the stent body 100 and can be used to immediately block aneurysms. Preferably, the film 200 is only covered on part of the outer surface of the stent body 100 to provide an outer layer film covering and a local film covering in this way, further reducing the influence of the film 200 on the stent body 100 and facilitating the control of the stent thickness.

[0040] Please refer to Figure 2 and Figure 3 and Figure 6 and Figure 7 In addition, the medical film covering device of the embodiment of the present invention further includes a plurality of film pieces 300. All the film pieces 300 are arranged in the inner cavity of the stent body 100 and are attached to the inner surface of the stent body 100. Furthermore, the axial two ends of the film 200 are connected to the stent body 100 through the plurality of film pieces 300, thereby fixing the position of the film 200 on the stent body 100.

[0041] It can be combined with Figure 1 and Figure 5It is understood that the proximal and distal ends of the membrane 200 are respectively connected to a plurality of diaphragms 300, and the plurality of diaphragms 300 connected to either end of the membrane 200 are arranged circumferentially along the stent body 100. Preferably, the diaphragm 300 is heat-melted to the membrane 200. The advantage is that the risk of stent deformation can be reduced, making the reliability and stability of the stent better and the performance more excellent. It should also be noted that the size of the diaphragm 300 is much smaller than that of the membrane 200. Therefore, the size of the diaphragm 300 is very small, which can maximize the avoidance of increasing the thickness of the covered stent and can also minimize the impact on the stent body 100. The thickness of the diaphragm 300 generally does not exceed the thickness of the membrane 200. The diaphragm 300 can be directly connected to the external membrane 200 through the grid 102, and the diaphragm 300 needs to be kept flat so that the edge of the diaphragm 300 is completely fused with the membrane 200. This covering method does not significantly increase the thickness of the medical covered device, and because the diaphragm 300 is arranged in the inner cavity of the stent body 100, it does not affect the appearance of the medical covered device, and also improves the flexibility of the stent body 100.

[0042] Preferably, each diaphragm 300 only covers the grid bar 101 between two adjacent intersections 103 and does not cover the intersection 103. If the diaphragm 300 covers the intersection 103, it is easy for the diaphragm 300 to be subjected to a large force and fall off. Preferably, each diaphragm 300 is not fixed to the grid bar 101 covering the diaphragm 300, so that the diaphragm 300 can slide on the grid bar 101 it covers; in this way, the influence of the diaphragm 300 and the membrane 200 on the stent body 100 can be further reduced, and problems such as further wrinkling and rupture of the membrane 200 can be avoided, ensuring the effectiveness of the membrane 200.

[0043] Furthermore, during the axial stretching process of the medical covered device, the intersection 103 of the grid bar 101 covering the diaphragm 300 and another grid bar 101 can also limit the diaphragm 300, so that the diaphragm 300 only slides on the grid bar 101 between two adjacent intersections 103 it covers and does not generate a large displacement. That is to say, each diaphragm 300 can be limited by the corresponding intersection 103 and only moves within a small area. In fact, only by blocking the diaphragm 300 in one direction can the diaphragm 300 be prevented from slipping out between two adjacent intersections 103. That is to say, during the stretching process, the stent body 100 elongates axially, while the diaphragm 300 can only slide relative to the frame body 100 in the middle direction and basically does not slide outward in the direction away from the middle. Therefore, the corresponding intersection 103 only needs to block in the direction in which the diaphragm 300 slides axially in the middle direction.

[0044] It should also be understood that when the stent body 100 is a braided stent, during axial stretching, the membrane 300 may slip out between two intersecting braided wires, resulting in a large displacement. This problem can be solved by selecting the braided wires at specific positions, so that the membrane 300 covers the braided wires at specific positions and will not slip out between two intersecting braided wires during axial stretching. This content will be described in detail in the following content.

[0045] When the membrane 300 slides only on the grid bars 101 between two adjacent intersections 103, a large displacement of the axial two ends of the membrane 200 relative to the stent body 100 can be avoided. This not only facilitates the operator to determine the position of the membrane 200, but also prevents the membrane 200 from further aggregating and wrinkling towards the midline direction of the stent body 100 due to the expansion and contraction of the stent body 100, thereby avoiding excessive wrinkling of the membrane 200 and causing thrombosis.

[0046] The material of the membrane 300 is the same as or different from that of the membrane 200. When the material of the membrane 300 is the same as that of the membrane 200, the bonding strength during heat melting of the membrane 300 and the membrane 200 is more excellent. While ensuring the heat melting strength, the effectiveness of fixing the membrane 200 can also be improved. In addition, after adding the membrane 300, there is no need to increase the biological evaluation test, which is convenient to use.

[0047] In view of the fact that the membrane 200 usually has no elasticity or very little elasticity and cannot expand and contract together with the stent body 100, preferably, after the membrane 200 covers the stent body 100, wrinkles are formed, which can not only reduce the influence on the stent body 100, but also make it not easy for the membrane 200 to rupture and other problems during the expansion and contraction of the stent, affecting the effectiveness of the membrane 200. Thus, the length of the membrane 200 in the installed state is less than its natural length when not installed, that is, when the stent body 100 is neither elongated nor contracted, the axial two ends of the membrane 200 are connected to the stent body 100, and at this time, the membrane 200 forms wrinkles. It should be understood that in the folded and contracted state, there are no wrinkles in the length direction of the membrane 200 along the axis of the stent body 100, but there are wrinkles in the circumferential direction of the stent body 100. On the contrary, in the expanded state, there are no wrinkles in the circumferential direction of the membrane 200, and there are wrinkles in the length direction. The proportion of the wrinkles formed by the membrane 200 is the shortening rate of the stent body 100, and the shortening rate can be 10% - 50%.

[0048] The diaphragm 300 can have various shapes, including but not limited to the illustrated rectangle, as long as the diaphragm 300 can be connected to the external film 200 to ensure the connection strength and does not affect the expansion and contraction of the stent body 100. Preferably, the diaphragm 300 is rectangular, which is convenient for processing and hot melting. The size of the diaphragm 300 is mainly set according to the size of the grid 102, and basically the width does not exceed the length of the grid rod 101 between two adjacent intersections 103. For example, the length of the diaphragm 300 is 0.2 mm to 5.0 mm, and the width is 0.2 mm to 5.0 mm.

[0049] In this embodiment, the grid 102 is diamond-shaped, and each diamond-shaped grid 102 is surrounded by four grid rods 101. The diaphragm 300 can be arranged on any one of the grid rods 101 of the grid 102. The same diaphragm 300 can cover one or more grid rods 101, that is, it can extend from one grid 102 to the next grid 102, or the next grid 102. Preferably, only one grid rod 101 is covered. The diaphragms 300 do not overlap and are all arranged independently of each other.

[0050] The multiple diaphragms 300 connected to any one end of the film 200 are arranged along the circumferential direction of the stent body 100 and are spaced apart from each other in the circumferential direction. The multiple diaphragms 300 connected to any one end of the film 200 are evenly or unevenly distributed along the circumferential direction of the stent body 100, preferably evenly distributed, so that the covered film 200 is stressed evenly and is not prone to more wrinkles.

[0051] There is no special requirement for the number of diaphragms 300 connected to any one end of the film 200. On the premise of meeting the connection strength, the number of diaphragms 300 is minimized to reduce the stent thickness. Optionally, 4 diaphragms 300 are connected to any one end of the film 200, but the actual number is not limited to 4 diaphragms 300.

[0052] See Figures 2 to 3 As shown, taking the braided stent as an example, optionally, the multiple diaphragms 300 connected to any one end of the film 200 are arranged at every other grid 102 in the circumferential direction of the stent body 100. Each diaphragm 300 covers the inner side of the grid rod 101 and is hot-melted with the external film 200 at high temperature. Actually, the multiple diaphragms 300 connected to any one end of the film 200 can also be arranged at intervals of multiple grids 102 in the circumferential direction of the stent body 100, or the multiple diaphragms 300 connected to any one end of the film 200 are arranged on each grid 102 in the circumferential direction of the stent body 100. Preferably, the multiple diaphragms 300 connected to any one end of the film 200 are arranged at every other grid 102 in the circumferential direction of the stent body 100, which can reduce the stent thickness better while ensuring the connection strength of the film 200.

[0053] A plurality of diaphragms 300 connected to either end of the membrane 200 are sequentially distributed in the circumferential direction of the stent body 100, and these diaphragms 300 can be aligned or offset in the axial direction of the stent body 100. Here, axial alignment means that a plurality of diaphragms 300 are arranged on the same circumference. At this time, a plurality of diaphragms 300 can be arranged at the same position of a plurality of meshes 102 in the circumferential direction. Axial offset means that a plurality of diaphragms 300 are arranged on different circumferences, so that a plurality of diaphragms 300 are arranged at different positions of a plurality of meshes 102 in the circumferential direction. However, preferably, a plurality of diaphragms 300 connected to the same end of the membrane 200 are axially aligned to avoid the risk of the membrane 200 warping due to uneven ends, thereby reducing the thrombus risk.

[0054] Continue to refer to Figure 2 and make an exemplary illustration based on the braided stent. In a preferred embodiment, each diaphragm 300 is provided with a non-melting zone 301 and a melting zone 302. The melting zone 302 is located at the edge of the diaphragm 300, that is, the melting zone 302 is provided outside the periphery of the non-melting zone 301. The diaphragm 300 is attached to the covered grid bar 101 through the non-melting zone 301, but the non-melting zone 301 is not fixed to the grid bar 101, that is, do not melt near the grid bar 101 to avoid affecting the expansion and contraction of the stent. By setting the non-melting zone 301, the range where no melting is required near the grid bar 101 can be more precisely controlled, and the influence on the stent body 100 can be minimized as much as possible. Especially for a braided stent, do not melt near the braided wire to avoid affecting the sliding of the braided wire and causing stent deformation. The melting zone 302 is used to melt with the external membrane 200 to ensure the connection strength. The sizes and shapes of the non-melting zone 301 and the melting zone 302 can be set as required. During installation, the diaphragm 300 can be centered or not centered on the grid bar 101.

[0055] In this embodiment, the diaphragm 300 is rectangular, which will not significantly increase the thickness of the stent. Preferably, the length of the non-melting zone 301 is 1 / 4 to 1 / 3 of the total length of the diaphragm 300, and the widths of the non-melting zone 301 and the melting zone 302 are equal.

[0056] It should also be noted that in addition to connecting the diaphragms 300 to both axial ends of the membrane 200, a plurality of diaphragms 300 can be further connected at a predetermined position (including but not limited to the middle position) between the proximal end and the distal end of the membrane 200 to better fix the membrane 200.

[0057] Preferably, the membrane 200 only covers a part of the outer surface of the stent body 100. Thus, as Figure 1 、 Figure 4 and Figure 5As shown, the stent body 100 includes a distal bare stent segment 120, a covered stent segment 130, and a proximal bare stent segment 140 that are axially connected in sequence from the distal end to the proximal end. Moreover, the membrane 200 only covers the entire outer surface of the covered stent segment 130 to completely enclose the covered stent segment 130. Except for the covered stent segment 130 being provided with the membrane 200, the entire proximal bare stent segment 140 is not covered with a membrane, and the proximal end of the distal bare stent segment 120 can be selectively covered with the membrane 200, and the remaining part of the distal bare stent segment 120 is not covered with a membrane. It should be understood that in order to facilitate the recovery and fixation of the membrane 200, the distal end of the membrane 200 preferably extends to the proximal end of the distal bare stent segment 120 for covering.

[0058] For a braided stent, as Figure 1 shown, a distal flared segment 110 can be further provided at the distal end of the distal bare stent segment 120, and a proximal flared segment 150 can be further provided at the proximal end of the proximal bare stent segment 140. The diameter of the distal flared segment 110 is greater than the diameter of the distal bare stent segment 120, the diameter of the proximal flared segment 150 is greater than the diameter of the proximal bare stent segment 140, and the diameters of both the distal bare stent segment 120 and the proximal bare stent segment 140 are not less than the diameter of the covered stent segment 130. The diameter of the covered stent segment 130 should be understood as the diameter after the covered stent segment 130 is sleeved with the membrane 200. The settings of the distal flared segment 110 and the proximal flared segment 150 enable the medical covered device to play a better anchoring role after being opened. Also, because the membrane 200 will, to a certain extent, restrain the covered stent segment 130, causing the covered stent segment 130 to contract in the axial direction after being restrained by the membrane 200. Therefore, the distal bare stent segment 120 is used for transition between the covered stent segment 130 and the distal flared segment 110, and the proximal bare stent segment 140 is used for transition between the covered stent segment 130 and the proximal flared segment 150, which helps the distal and proximal ends of the medical covered device to adhere to the wall after release and prevent endoleakage. The diameters of the distal flared segment 110 and the proximal flared segment 150 can be the same or different. Preferably, the diameter of the distal flared segment 110 is 1.2 to 4 times the diameter of the distal bare stent segment 120, and the diameter of the proximal flared segment 150 is 1.2 to 4 times the diameter of the proximal bare stent segment 140. This enables the medical covered device to be better anchored in the blood vessel after release and reduces its risk of displacement. On the premise of ensuring sufficient anchoring force, the lengths of the distal flared segment 110 and the proximal flared segment 150 are as short as possible.

[0059] Whether it is a braided stent or a cut stent, the diameters of the distal bare stent segment 120 and the proximal bare stent segment 140 are preferably 1 to 1.5 times the diameter of the covered stent segment 130, which can enable the distal and proximal ends of the medical covered device to adhere to the wall better after release and achieve a better anti-endoleakage effect.

[0060] The length of the distal bare stent segment 120 should be as short as possible. After the medical film-covered device is released from the delivery system, it is beneficial for the operator (such as a doctor) to determine the position of the film 200 and achieve immediate occlusion of the aneurysm. The proximal bare stent segment 140 should be long enough to facilitate the re-recovery and repositioning of the medical film-covered device. For example, when the proximal bare stent segment 140 is still constrained in the delivery system, contrast agent can be injected to observe whether the film-covered stent segment 130 has occluded the aneurysm. If not, the medical film-covered device can be recovered, repositioned, and then released. The length of the proximal bare stent segment 140 should not be too long either. If it is too long, after the medical film-covered device is fully released, the proximal bare stent segment 140 may block the branch vessels.

[0061] Preferably, the length of the distal flared segment 110 is 1 mm to 4 mm, and the length of the proximal flared segment 150 is 1 mm to 4 mm.

[0062] Preferably, the length of the distal bare stent segment 120 is 0 to 4 mm, the length of the film-covered stent segment 130 is 4 mm to 30 mm, and the length of the proximal bare stent segment 140 is 2 mm to 5 mm.

[0063] In addition, for the cutting stent, at least one of the distal bare stent segment 120 and the proximal bare stent segment 140 is preferably a closed-loop structure, and the film-covered stent segment 130 is an open-loop structure. In some embodiments, both the distal bare stent segment 120 and the proximal bare stent segment 140 are closed-loop structures. In other embodiments, the distal bare stent segment 120 is an open-loop structure and the proximal bare stent segment 140 is a closed-loop structure. The closed-loop structure means that the number of connecting rods 107 in the cutting stent is the same as the number of wave peaks or wave valleys on the stent wavebands connected by the connecting rods 107. Setting the closed-loop structure can increase the stability and support of the film-covered stent, and when the release position is inappropriate, the distal end of the film-covered stent can also be recovered. The open-loop structure means that the number of connecting rods 107 is less than the number of wave peaks or wave valleys on the stent wavebands connected by the connecting rods 107. After setting the open-loop structure, the bending flexibility of the film-covered stent at the film-covered position is increased, and the bending and wall-adhering performance of the film-covered stent is also increased, thereby preventing endoleakage.

[0064] See Figure 4 and Figure 5 For further understanding. The cutting stent is defined with a plurality of stent wavebands (rings), the stent wavebands are arranged in sequence along the axial direction of the cutting stent, and adjacent stent wavebands are connected by a plurality of circumferentially distributed connecting rods 107. Each connecting rod 107 connects the wave peaks and wave valleys of adjacent stent wavebands. The connecting rods 107 can play a role in supporting and reducing the stent deflection. Preferably, the proximal end of the film 200 is arranged on the open-loop structure, and the distal end of the film 200 is arranged on the closed-loop structure, which is beneficial for the recovery and repositioning of the distal end of the film-covered stent.

[0065] Such as Figure 1As shown, in one embodiment, a developer spring 104 is provided on the distal bell mouth section 110, and a developer sleeve 105 is provided on the proximal bell mouth section 150 to position the medical film covering device. Preferably, a plurality of developer springs 104 are circumferentially provided on the distal bell mouth section 110. Generally, 3 to 4 developer springs 104 are provided. Preferably, a plurality of developer sleeves 105 are circumferentially provided on the proximal bell mouth section 150, such as at least 3 to 4 developer sleeves 105. In particular, the developer sleeve 105 on the proximal bell mouth section 150 can not only be developed, but also fix the wire ends of the braided wire 101, avoiding the exposure or formation of tips of the braided wire ends at the proximal end, thereby reducing the damage to blood vessels.

[0066] As Figure 3 , Figure 6 and Figure 7 shown, preferably, developer structures 106 are provided at both the proximal and distal ends of the film-covered stent section 130. Generally, a plurality of developer structures 106 are provided at any one end of the film-covered stent section 130, such as 3 to 4 developer structures 106. The plurality of developer structures 106 on each end are uniformly or non-uniformly distributed along the circumference of the stent body 100. The developer structure 106 is positioned at the end edge of the film 200, and at least part of the developer structure 106 can be covered by the film 200, and preferably all of it can be covered by the film 200, which can better determine the position of the film 200. It should also be understood that the proximal end of the film-covered stent section 130 is the distal end of the proximal bare stent section 140, and the distal end of the film-covered stent section 130 is the proximal end of the distal bare stent section 120. Equivalently, developer structures 106 are provided at the distal end of the proximal bare stent section 140 and the proximal end of the distal bare stent section 120. The developer structure 106 can be a developer spring 104, which is made by winding a developable metal wire around the grid rod 101, and the developable metal wire can be further adhesively fixed to the grid rod 101.

[0067] However, there can be various ways to achieve the development method, including but not limited to the developer spring 104 and the developer sleeve 105 listed above.

[0068] Referring Figure 1 , if the stent body 100 is a braided stent, the braided wires at its proximal and distal ends form closed loops, and there is no exposure or tip of the wire ends, avoiding the exposure or formation of tips of the end wires, and thus avoiding damage to blood vessels caused by both ends of the braided stent. When the stent body 100 is a braided stent, the number of braided wire ends includes but is not limited to 8, 12, 16, 24, 32, 48, or 64.

[0069] The present invention will be further illustrated by the following exemplary embodiments, but these exemplary embodiments are only illustrative, and their purpose is to enable those skilled in the art to understand the present invention, rather than to limit the protection scope of the present invention.

[0070] In an exemplary embodiment, the stent body 100 is a braided stent with 16 braided filaments. The membrane 200 is made of expanded polytetrafluoroethylene (ePTFE) material, and the material of the membrane sheet 300 is the same as that of the membrane 200. Any one end of the membrane 200 is heat-melted with a plurality of axially-aligned membrane sheets 300. Moreover, each of the plurality of membrane sheets 300 is disposed at every other grid 102 in the circumferential direction of the stent body 100, and each membrane sheet 300 only covers one braided filament; then local heat melting is performed to ensure that the edge of the membrane sheet 300 is completely fused with the external membrane 200 until the boundary of the membrane sheet 300 is no longer visible, which not only ensures the heat-melting strength but also does not affect the appearance, and thus a medical membrane-covered device with 4 membrane sheets 300 connected to each of the proximal end and the distal end is obtained.

[0071] In an exemplary embodiment, the membrane sheet 300 covers multiple braided filaments at the same time, and one or more membrane sheets 300 are covered on one braided filament.

[0072] In an exemplary embodiment, the multiple membrane sheets 300 connected to any one end of the membrane 200 are disposed at intervals of multiple grids 102 or without intervals of grids 102 in the circumferential direction of the stent body 100, and the number of the spaced grids 102 may be the same or different. For example, the membrane sheets 300 are disposed in such ways as spaced by 1 grid 102, spaced by 2 grids 102, spaced by 3 grids 103, etc.

[0073] In an exemplary embodiment, any one end of the membrane 200 is heat-melted with a plurality of axially-offset membrane sheets 300. The multiple membrane sheets 300 connected to any one end of the membrane 200 may be partially offset or all offset; when axially offset, the multiple membrane sheets 300 may have various geometric arrangement paths, such as zigzag, wavy, etc., which are not specifically limited.

[0074] In an exemplary embodiment, the material of the membrane 200 is different from that of the membrane sheet 300. For example, the membrane sheet 300 is made of ePTFE material, and the membrane 200 is made of polyester (PET), polyurethane (TPU), polylactic acid (PLA), or other polymer materials.

[0075] In an exemplary embodiment, in addition to disposing the membrane sheets 300 at both axial ends of the membrane 200, a plurality of membrane sheets 300 are also heat-melted and connected at an intermediate position between the proximal end and the distal end of the membrane 200. At this time, all the membrane sheets 300 are disposed in the inner cavity of the stent body 100.

[0076] In another exemplary embodiment, the stent body 100 is a cutting stent. After the film 200 covers the outside of the stent body 100, a plurality of membrane pieces 300 are connected to both axial ends of the film 200. The membrane pieces 300 are disposed in the inner cavity of the cutting stent body 100 and are attached to the corresponding wave rods (i.e., the grid rods 101); then local heat fusion is performed to ensure that the edges of the membrane pieces 300 are completely fused with the film 200 until the boundaries of the membrane pieces 300 are no longer visible, thereby obtaining a medical film-covered device with 4 membrane pieces 300 connected to the proximal and distal ends respectively. The method of covering the cutting stent with a film is basically the same as that of covering the braided stent, and will not be described in detail here.

[0077] When the stent body 100 is a braided stent, the braided wire covering the membrane piece 300 is pressed on another braided wire at the corresponding intersection 103, so that the other braided wire pressed by the braided wire covering the membrane piece 300 can limit the membrane piece 300 during the stretching process of the stent body 100, that is, the membrane piece 300 will not slip out between the two braided wires during the stretching of the stent, and the membrane piece 300 can only slide on the braided wires between two adjacent intersections 103. This method can ensure that the external film 200 does not undergo a large displacement during the stretching of the stent, and thus the relative position between the film 200 and the stent body 100 does not change significantly.

[0078] Please refer to Figure 2 and Figure 3 , when the stent body 100 is axially stretched, the membrane piece 300 has a tendency to slide towards the midline direction of the stent body 100 (the midline can be understood as the symmetry line perpendicular to the axis). At this time, the membrane piece 300 will be blocked by the braided wire below and cannot further displace. On the contrary, if the braided wire covering the membrane piece 300 is pressed under another braided wire that is intertwined with it, and then when the stent body 100 is axially stretched and the membrane piece 300 slides towards the midline direction of the stent body 100, the membrane piece 300 will slide out between the two intertwined braided wires, resulting in a large displacement. Therefore, the braided wire covering the membrane piece 300 needs to be pressed on another braided wire that is intertwined with it to block the membrane piece 300. Generally, blocking the membrane piece 300 in one direction can prevent the membrane piece 300 from slipping out between the two crossed braided wires. Specifically, the braided wire covering the membrane piece 300 is the upper wire 101a at the current intersection 103, but it is the lower wire 101b at another intersection 103. The upper wire 101a covering the membrane piece 300 only refers to the intersection 103 where the membrane piece 300 needs to be limited.

[0079] When the braided wire covering the diaphragm 300 is the upper-layer wire 101a at the corresponding intersection 103, it can avoid large displacement of the two axial ends of the membrane 200 relative to the stent body 100, better fix the position of the membrane 200 on the stent body 100, prevent the membrane 200 from gathering and wrinkling towards the midline direction due to the stretching of the stent body 100, and further avoid excessive wrinkling of the membrane 200 resulting in thrombosis. In addition, the developing structures 106 are usually preset at the two end edges of the membrane 200 in advance. If the membrane 200 does not have large displacement, it can ensure that the two end edges of the membrane 200 are exactly at the developing structures 106, which is convenient for doctors to locate the position of the membrane 200, and then release the membrane 200 more accurately at the aneurysm neck, providing convenience for immediately blocking the aneurysm.

[0080] Finally, based on the same inventive concept, the present invention also provides a preparation method for preparing the medical covered device provided in any of the above preferred embodiments. The preparation method includes:

[0081] Providing the stent body 100;

[0082] Covering the membrane 200 on at least part of the outer surface of the stent body 100. Preferably, the membrane 200 forms wrinkles.

[0083] Connecting the proximal end and the distal end of the membrane 200 to a plurality of diaphragms 300 respectively arranged in the inner cavity of the stent body 100 and circumferentially distributed. Preferably, the diaphragms 300 and the membrane 200 are heat-melt connected.

[0084] Further, when preparing the medical covered device, each diaphragm 300 is covered on the grid rod 101 between two adjacent intersections 103, and each diaphragm 300 is not fixed to the grid rod 101 covering the diaphragm 300.

[0085] Further, each diaphragm 300 is limited by the corresponding intersection 103, so that the diaphragm 300 can only move on the grid rod 101 between two adjacent intersections 103.

[0086] It should also be noted that the manner of setting the membrane 200 on the stent body 100 is not limited. For example, the membrane 200 is obtained by electrospinning directly on the stent body 100, or a sheet-shaped covered membrane is prepared first and then wound around the stent body 100 to obtain the membrane 200, or a tubular covered membrane is prepared first and then sleeved on the stent body 100 to obtain the membrane 200, or other methods.

[0087] Compared with the prior art, in the medical film covering device provided by the present invention, neither suture nor double-layer film covering is adopted. Instead, a single-layer film is hot-melt fixed on the stent body through multiple film pieces, and all the film pieces are only arranged in the inner cavity of the stent body. In this way, the combination of the film and the stent body can be realized, while the thickness of the device can be maximally avoided from increasing, the appearance of the device is not affected, the influence of the film covering on the stent body can be reduced, and the flexibility of the device can be improved. The present invention also overcomes the defects of the existing film covering technology, providing conditions for the film-covered stent to enter a small delivery system and reach smaller blood vessels at a farther end. In addition, the method of hot-melting the outer film by the film pieces can adapt to the elongation and shortening rate of more than 100% of the braided stent, does not affect the movement of the braided wires, and will not cause the stent to deform due to film covering, ensuring the mechanical properties of the stent. Moreover, compared with the suture method, the method of hot-melting the outer film by the film pieces is simpler and easier to be mechanized, simplifying the manufacturing process and improving the 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 field of the present invention according to the above disclosure shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A medical film covering device, characterized in that, it includes a stent body, a film and film pieces. The number of the film pieces is multiple. All the film pieces are attached to the inner surface of the stent body. The film covers at least part of the outer surface of the stent body. Two ends of the film are respectively connected to multiple film pieces distributed along the circumferential direction of the stent body.

2. The medical film covering device according to claim 1, characterized in that, the stent body includes a plurality of grid rods. The plurality of grid rods intersect with each other to form grids and intersections. Each film piece covers the grid rods between two adjacent intersections. Each film piece is not fixed to the grid rods covering it.

3. The medical film covering device according to claim 2, characterized in that, during the axial stretching process of the medical film covering device, each film piece can be limited by the corresponding intersection, so that each film piece can only slide on the grid rods between two adjacent intersections it covers.

4. The medical film covering device according to claim 2, characterized in that, the film is connected to the film piece by hot melting. Each film piece is provided with a non-hot melting area and a hot melting area. The hot melting area is located at the edge of the film piece. The non-hot melting area is attached to the grid rods. The hot melting area is connected to the film by hot melting.

5. The medical film covering device according to claim 2, characterized in that, the multiple film pieces connected to any one end of the film are arranged at intervals of one or more grids in the circumferential direction of the stent body, or the multiple film pieces connected to any one end of the film are arranged on each grid in the circumferential direction of the stent body.

6. The medical film covering device according to claim 2, characterized in that, the multiple film pieces connected to any one end of the film are aligned or staggered in the axial direction of the stent body.

7. The medical film covering device according to claim 2, characterized in that, the same film piece covers one or more grid rods.

8. The medical film covering device according to claim 1, characterized in that, the material of the film is the same as or different from the material of the film piece. The thickness of the film piece does not exceed the thickness of the film.

9. The medical film covering device according to claim 1, characterized in that, the length of the film piece is 0.2 mm to 5.0 mm, and the width of the film piece is 0.2 mm to 5.0 mm.

10. The medical film covering device according to claim 1, characterized in that, after the film covers the stent body, wrinkles are formed.

11. The medical film covering device according to claim 1, characterized in that, the stent body is a braided stent or a cut stent.

12. The medical film covering device according to claim 1, characterized in that, the stent body includes a plurality of stent segments. The plurality of stent segments include a distal bare stent segment, a film-covered stent segment and a proximal bare stent segment that are axially connected in sequence from the distal end to the proximal end. The film covers the entire outer surface of the film-covered stent segment.

13. The medical film covering device according to claim 12, characterized in that, The stent body is a cutting stent, the covered 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.

14. The medical covered device according to claim 1, wherein, a predetermined part between the proximal end and the distal end of the membrane is connected to a plurality of other said membrane pieces.

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