Covered stent

Abstract

The present application relates to a kind of film-covered stents, including window area and the non-window area being axially connected with the window area, the window area includes multiple first wave turns being arranged at intervals in the axial direction, and the first film covering multiple first wave turns, the softness of the first film is 0.3~1.The film-covered stent is beneficial to avoid shortening and slow down the limitation to windowing.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of interventional medical devices, in particular to a covered stent. BACKGROUND

[0002] This section provides background information only and can not necessarily be prior art.

[0003] With the rise of interventional therapy, endovascular stent implantation for vascular diseases (e.g., aortic aneurysm, aortic dissection, etc.) has received more and more widespread social attention. Compared with traditional surgery, this method has the advantages of less trauma, high efficacy, low risk, and short hospital stay, and has become an effective method for treating vascular diseases.

[0004] In the past decade, endovascular stent grafting has been widely used in the treatment of aneurysm and dissection, and has achieved good short-term and medium-term results. Because of its exact efficacy, small trauma, rapid recovery and fewer complications, it has become a first-line treatment. Among them, for aortic arch lesions, because it involves three major arterial branches of the head and arm trunk, left common carotid artery and left subclavian artery, how to establish the important branches of the aorta is a major problem in endovascular aneurysm repair (EVAR).

[0005] The insitu fenestration technique is one of the methods for establishing branches. The insitu fenestration technique refers to covering the branch blood vessels after releasing the aortic stent, then using puncture, laser drilling or balloon dilation of the covered stent to open a hole on the cover film on the aortic stent through the distal end of the branch artery retrograde approach, and finally placing a branch stent to reconstruct the blood supply of the branch artery.

[0006] However, the covered stent generally includes a plurality of wave coils arranged at intervals in the axial direction, and the wave coils are usually connected in the axial direction by axial connectors to provide axial support, and these connectors usually limit the position and size of the fenestration, thereby affecting the accuracy of the fenestration position, and in severe cases, it can cause surgical failure. However, when the axial connectors are omitted, the covered stent is prone to shortening. SUMMARY

[0007] Therefore, it is necessary to provide a covered stent that can help avoid shortening and reduce the limitation on fenestration.

[0008] A covered stent includes a fenestration area and a non-fenestration area axially connected to the fenestration area, the fenestration area includes a plurality of first wave coils arranged at intervals in the axial direction, and a first cover film covering the plurality of first wave coils, the softness of the first cover film is 0.3-1.

[0009] In one of the embodiments, the non-windowed area comprises a plurality of second wave turns arranged in an axial direction and a second film covering the plurality of second wave turns, and the first film has a softness less than that of the second film.

[0010] In one of the embodiments, the first film has a thickness greater than that of the second film.

[0011] In one of the embodiments, the first film comprises a base film and a plurality of film pieces arranged on the base film, each of the film pieces is located between two adjacent first wave turns, and each of the film pieces is arranged in a circumferential direction of the windowed area.

[0012] In one of the embodiments, a distance between two adjacent first wave turns is h1, a wave height of each of the first wave turns is h2, the film piece is in a strip shape, a width of the film piece is d1, and the h1, h2 and d1 satisfy: d1≤h1-h2.

[0013] In one of the embodiments, a width of a middle part of the film piece is greater than widths of two ends of the film piece, and the middle part of the film piece is located at a large bending side of the windowed area.

[0014] In one of the embodiments, the first film comprises a base film and at least one film piece arranged on the base film, and each of the film pieces extends in an axial direction of the windowed area.

[0015] In one of the embodiments, the film piece is in a strip shape, a width of the film piece is D, a wave width of the first wave turn is h3, and D≤h3.

[0016] In one of the embodiments, one of the film pieces is located at the large bending side of the windowed area.

[0017] In one of the embodiments, two of the film pieces are symmetrically arranged on two sides of the windowed area with a longitudinal center axis of the windowed area as a symmetric axis.

[0018] In one of the embodiments, a plurality of the film pieces are arranged in a circumferential direction of the windowed area with an interval, and each of the film pieces extends in an axial direction of the windowed area.

[0019] In one of the embodiments, the first film comprises a base film and a plurality of film pieces arranged on the base film, each of the film pieces is arranged between two adjacent first wave turns, and an axial length of each of the film pieces is less than a distance between two adjacent first wave turns, a plurality of the film pieces form a row of film pieces in an axial direction of the windowed area, and a plurality of rows of the film pieces are distributed in a circumferential direction of the windowed area with an interval.

[0020] In one embodiment, the first covering film comprises a base film and at least one film piece arranged on the base film, and among the first wave turns, two first wave turns close to the proximal end and two first wave turns close to the distal end are included, the film piece extends in the two first wave turns close to the proximal end along the axial direction of the fenestrated area, and the two first wave turns close to the distal end each comprises a long wave rod and a short wave rod.

[0021] In one embodiment, the first covering film comprises a base film and at least one film piece arranged on the base film, and a through hole is arranged in the middle of the film piece.

[0022] The softness of the first covering film of the fenestrated area of the covering stent is 0.3-1, so that the first covering film is not prone to shortening, and thus the axial connecting piece can be omitted from the fenestrated area, thereby avoiding the restriction of the axial connecting piece on the fenestration. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 An embodiment of the covering stent in an expanded state is shown in the figure;

[0024] Figure 2 Another embodiment of the covering stent in an expanded state is shown in the figure;

[0025] Figure 3 A partial enlarged view of Figure 2 is shown in the figure;

[0026] Figure 4 Another embodiment of the covering stent in an expanded state is shown in the figure;

[0027] Figure 5 A schematic view of the covering stent in a bent state is shown in the figure; Figure 4

[0028] A schematic view of the film piece of one embodiment is shown in the figure; Figure 6

[0029] Another embodiment of the covering stent in an expanded state is shown in the figure; Figure 7

[0030] A schematic view of the covering stent in a bent state is shown in the figure; Figure 8 Figure 7 A partial enlarged view of

[0031] is shown in the figure; Figure 9 Figure 7 Another embodiment of the covering stent in an expanded state is shown in the figure;

[0032] Figure 10 A schematic view of the covering stent in a bent state is shown in the figure;

[0033] Figure 11 Figure 10 ​A schematic view of a covered stent in a curved state;

[0034] Figure 12 A schematic view of a covered stent in an expanded state according to another embodiment;

[0035] Figure 13 A schematic view of a covered stent in an expanded state according to another embodiment;

[0036] Figure 14 A schematic view of a covered stent in an expanded state according to another embodiment;

[0037] Figure 15 A schematic view of a membrane according to an embodiment;

[0038] Figure 16 A schematic view of a covered stent in an expanded state according to another embodiment;

[0039] Figure 17 A schematic view of a covered stent in an expanded state according to another embodiment;

[0040] Figure 18 A schematic view of a covered stent in an expanded state according to another embodiment;

[0041] Figure 19 A schematic view of a membrane according to an embodiment. DETAILED DESCRIPTION

[0042] In order to make the above objectives, features and advantages of the present application more clear and comprehensible, specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. It will be apparent, however, to one skilled in the art that the present application can be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order to avoid unnecessarily obscuring the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0044] In the field of interventional medical devices, the term "distal end" is defined as the end furthest from the heart, and the term "proximal end" is defined as the end closest to the heart. The term "axial" refers to a direction parallel to a line connecting a center of the distal end and a center of the proximal end of the medical device. The term "radial" refers to a direction perpendicular to the axial direction.

[0045] Reference is made to Figure 1The covered stent 100 of one embodiment includes a fenestrated area 20 and a non-fenestrated area 40, both of which are lumen structures, and the fenestrated area 20 and the non-fenestrated area 40 are axially connected to form the covered stent 100 of the lumen structure. The covered stent 100 has openings at both ends. When the covered stent 100 is implanted into a body vessel, the non-fenestrated area 40 is located at a lesion site in the body vessel, and the fenestrated area 20 is located at a corresponding site of a branch vessel in the body vessel. The branch blood supply is reconstructed by fenestrating the fenestrated area 20. In the body vessel, the fenestrated area 20 is located at a proximal end, and the non-fenestrated area 40 is located at a distal end.

[0046] The fenestrated area 20 includes a plurality of first wave loops 210 arranged at intervals in the axial direction and a first covering 220 covering the plurality of first wave loops 210.

[0047] The plurality of first wave loops 210 are independent of each other, that is, no axial connecting member is arranged between adjacent first wave loops 210. The plurality of first wave loops 210 are connected into one body by the first covering 220. In one embodiment, each first wave loop 210 includes a plurality of wave rods 211, and each wave rod 211 is connected end to end to form a closed Z-shaped wave structure. In one embodiment, each first wave loop 210 includes a plurality of wave rods 211 and a plurality of arc-shaped connecting members (not shown in the figure). The plurality of wave rods 211 and the plurality of arc-shaped connecting members are alternately connected to form a closed, ring-shaped first wave loop 210.

[0048] The material of the first wave loop 210 is a material with good biocompatibility, for example, nickel-titanium alloy, stainless steel, etc.

[0049] In one embodiment, the wave height of the first wave loop 210 is 6-11 mm, and the wave width is 6-17 mm. On the one hand, this avoids a too steep wave that causes obvious stress concentration at the wave peak. Stress concentration is easy to cause damage to the blood vessel, and in the case of stress concentration, the fatigue performance of the covered stent 100 is poor. On the other hand, this avoids a too slow wave that causes the covered stent 100 to be difficult to compress in the radial direction and difficult to be put into the sheath tube of the delivery system.

[0050] The softness of the first covering 220 is 0.3-1. The definition of softness is as follows: when a tensile testing machine is used to press a sample into a gap (the width of the gap is 15 cm) to a certain depth (for example, 10 mm) under specified conditions, the reciprocal of the force value is the softness. The specified conditions refer to the gap width and the pressing depth. Experiments show that when the value of the softness is 0.3-1, the first covering 220 has certain resistance to shortening.

[0051] The lower the flexibility, the better the resistance to shortening. When the flexibility is too low, below 0.3, it will affect the overall flexibility of the fenestration area 20, making it difficult for the fenestration area 20 to adapt to changes in the morphology of the blood vessel. When the flexibility is too high, above 1, the resistance to shortening is insufficient. Therefore, a first covering membrane 220 with a flexibility of 0.3 to 1 is used to balance the resistance to shortening and overall flexibility.

[0052] In one embodiment, the first coating 220 includes a base film 221 and a diaphragm 222 disposed on the base film 221. The diaphragm 222 may be disposed on the outer surface, inner surface, or embedded in the base film 221. In one embodiment, the diaphragm 222 is a continuous sheet structure. In one embodiment, the shape and size of the diaphragm 222 are consistent with the shape and size of the base film 221. In one embodiment, the shape and size of the diaphragm 222 are equal to the shape and size of the region enclosed by the first wavering coil 210 closest to the proximal end and the first wavering coil 210 furthest from the proximal end.

[0053] The bottom membrane 221 and membrane sheet 222 are made of biocompatible materials, such as e-PTFE and PET. The bottom membrane 221 and membrane sheet 222 can be made of the same or different materials.

[0054] In one embodiment, the thickness of the bottom film 221 is 0.1 to 0.3 mm, and the thickness of the film 222 is 0.3 to 1 mm.

[0055] In one embodiment, the diaphragm 222 is not a continuous structure; there are multiple diaphragms 222, each with a shape and size consistent with the shape and size of the region enclosed by two adjacent first wave loops 210. A diaphragm 222 is disposed between two adjacent first wave loops 210, and each diaphragm 222 extends circumferentially along the fenestration region 20. In one embodiment, the flexibility of the multiple diaphragms 222 increases sequentially from the proximal end to the distal end. Since the direction of blood flow is from the proximal end to the distal end, the impact force of blood flow is greater closer to the proximal end. Therefore, the closer to the proximal end, the less flexible the diaphragm 222 is, and the better it can resist the impact of blood flow.

[0056] In one embodiment, such as Figure 1 As shown, the diaphragm 222 includes four regions, 1, 2, 3, and 4, arranged sequentially from the proximal end to the distal end. The softness gradually increases from region 1 to region 4. In one embodiment, when the softness of region 1 is M, the softness of region 2 is 1.05M, the softness of region 3 is 1.1M, and the softness of region 4 is 1.15M. The value of M can be from 0.3 to 1. Each region can be a diaphragm 222, and four independent diaphragms 222 are used to form the four regions 1, 2, 3, and 4. Alternatively, regions 1, 2, 3, and 4 can be four regions of a single diaphragm 222.

[0057] In an embodiment, as shown in Figure 2 , the first covering film 220 comprises a bottom film 221 and a plurality of film pieces 222 arranged on the bottom film 221, each film piece 222 is located between two adjacent first wave loops 210, each film piece 222 is arranged around the circumference of the window area 20, and the film piece 222 is in a strip shape.

[0058] In an embodiment, as shown in Figure 2 and Figure 3 , the distance between two adjacent first wave loops 210 (the distance from the wave peak to the wave peak or the distance from the wave valley to the wave valley) is h1, and the wave height of each first wave loop 210 is h2. The width of the film piece 222 is d1. h1, h2 and d1 satisfy: d1≤h1-h2. In this way, the softness of the area of the first covering film 220 where the film piece 222 is arranged is smaller, which can limit the relative displacement between adjacent first wave loops 210, so that the anti-shortening performance of the window area 20 is better. Moreover, because the plurality of film pieces 222 are arranged at intervals, the influence on the flexibility of the window area 20 is smaller, so as to ensure that the window area 20 has sufficient bending performance to conform to the different morphologies of the blood vessels of different individuals. In an embodiment, h1 is 8-25 mm, and h2 is 6-12 mm.

[0059] In an embodiment, as shown in Figure 4 , the width of the middle part of the film piece 222 is greater than the width of the two ends of the film piece 222, and the width of the film piece 222 gradually decreases from the middle part to one end, and the width of the film piece 222 gradually decreases from the middle part to the other end. When the covered stent 100 is bent, the middle part of the film piece 222 is located at the large bending side A of the window area 20, and the two ends of the film piece 222 are located at the small bending side B of the window area 20, as shown in Figure 5 . It should be noted that the width of the middle part of the film piece 222 is ≤h1-h2.

[0060] When the covered stent 100 is implanted in the blood vessel, the covered stent 100 bends to conform to the morphology of the blood vessel, forming a large bending side A and a small bending side B. When changing from a non-bent state to a bent state, the axial distance between two adjacent first wave loops 210 remains basically unchanged at the large bending side A, and the axial distance between two adjacent first wave loops 210 becomes smaller at the small bending side B. In an embodiment, as shown in Figure 6 , the width of the middle part of the film piece 222 is D1, and the width of the two ends of the film piece 222 is D2. As shown in Figure 5 , the radius of the large bending side A is R1, and the radius of the small bending side B is R2. D1, D2, R1 and R2 satisfy: D2=D1*R2 / R1. The advantage of this design is that when the covered stent 100 bends to conform to the morphology of the blood vessel, the part of the first covering film 220 located at the small bending side B will not be folded or will be less likely to be folded. The sizes of R1 and R2 can be designed according to the corresponding blood vessel morphology.

[0061] Please see Figure 7 In one embodiment, each diaphragm 222 is disposed along the axial direction of the fenestration region 20. The two axially opposite ends of each diaphragm 222 may extend axially to the outer side of the first wave loop 210 closest to the heart and the outer side of the first wave loop 210 furthest from the heart, or they may be located on the inner side. Figure 7 The image shows the area located on the inside. For example... Figure 8 As shown, in one embodiment, when the number of diaphragms 222 is one, the diaphragm 222 is located on the large curved side A of the window area 20.

[0062] The diaphragm 222, located at the greater curvature side A, provides support and improves the anti-shortening performance of side A, while still allowing it to bend according to the vessel's shape on the lesser curvature side B. Since side A corresponds to the greater curvature of the aortic arch, near the brachiocephalic column, left common carotid artery, and left subclavian artery, side A is the specific fenestration location for fenestration zone 20. Compared to rigid axial metal connectors, the non-rigid diaphragm 222 makes fenestration easier to achieve.

[0063] Furthermore, after a branch stent is inserted at the fenestration site, the long-term blood flow pressure can cause the fenestration opening to gradually enlarge, leading to internal leakage. Because the membrane 222 has relatively low flexibility, the opening in the fenestration area has greater resistance to deformation. In one embodiment, as... Figure 9 As shown, the width of the diaphragm 222 is D, and the width of a single wave of the first wave loop 210 is h3, where D ≤ h3. If D is greater than h3, when the adjacent first wave loops 210 bend to conform to the shape of the blood vessel, the diaphragm 222 will hinder the deformation of the first wave loops 210 and make it difficult to adapt to the shape of the blood vessel and bend.

[0064] Please see Figure 10 In one embodiment, two diaphragms 222 are used, each arranged along the axial direction of the window area 20. The two diaphragms 222 are symmetrically arranged on both sides of the window area 20 with the longitudinal central axis of the window area 20 as the axis of symmetry. Figure 11 As shown, the two sides are not the large bend side A and the small bend side B. The plane containing these two sides is perpendicular to or intersects with the plane that passes through both the large bend side A and the small bend side B. This arrangement ensures that the diaphragm 222 is not located at a specific opening position in the opening area 20, thus improving the anti-shortening effect without causing difficulties in the opening operation.

[0065] Please see Figure 12In an embodiment, the number of the membrane pieces 222 is more than two. The plurality of the membrane pieces 222 are arranged along the circumferential direction of the fenestrated area 20, and each of the membrane pieces 222 extends along the axial direction of the fenestrated area 20. The plurality of the membrane pieces 222 can be arranged according to actual needs. For example, in an embodiment, the plurality of the membrane pieces 222 are arranged at both sides of the fenestrated area 20, but none of the membrane pieces 222 are arranged at the large bending side A and the small bending side B. In another embodiment, as shown in FIG. 2B, each of the membrane pieces 222 extends along the axial direction of the fenestrated area 20, but the plurality of the membrane pieces 222 are arranged along the entire circumferential direction of the fenestrated area 20, and the membrane pieces 222 are arranged at both the large bending side A and the small bending side B. Figure 13

[0066] Referring to FIG. 2A, Figure 14 In an embodiment, the number of the membrane pieces 222 is more than two. The plurality of the membrane pieces 222 are arranged along the circumferential direction of the fenestrated area 20, and each of the membrane pieces 222 extends along the axial direction of the fenestrated area 20. The plurality of the membrane pieces 222 can be arranged according to actual needs. For example, in an embodiment, the plurality of the membrane pieces 222 are arranged at both sides of the fenestrated area 20, but none of the membrane pieces 222 are arranged at the large bending side A and the small bending side B. In another embodiment, as shown in FIG. 2B, each of the membrane pieces 222 extends along the axial direction of the fenestrated area 20, but the plurality of the membrane pieces 222 are arranged along the entire circumferential direction of the fenestrated area 20, and the membrane pieces 222 are arranged at both the large bending side A and the small bending side B.

[0067] Referring to FIG. 2A, Figure 15 In an embodiment, one end of the membrane piece 222 is triangular, and the other end is cut into a shape of an angle, so that the membrane piece 222 is arranged between the two adjacent first wave coils 210 and matches the shape of the area surrounded by the two adjacent first wave coils 210.

[0068] In an embodiment, the axial length d of the membrane piece 222 is less than the distance between the wave crests of the two adjacent first wave coils 210. Figure 15 ​The axial length d of the membrane 222 gradually decreases from the large bending side A to the small bending side B, i.e. the axial length d of the membrane 222 at the large bending side A is the largest, and the axial length d of the membrane 222 at the small bending side B is the smallest. In this way, when the covered stent 100 is bent to conform to the shape of the blood vessel, the distance between the adjacent first wave 210 gradually decreases from the large bending side A to the small bending side B, and the arrangement of the membrane 222 conforms to the trend of the distance decreasing, so that the membrane 222 is not extruded by the first wave 210 when the covered stent 100 is in the bent state. In an embodiment, the radius of the large bending side A is R1, the radius of the small bending side B is R2, the distance between the adjacent two first waves 210 (the distance between the wave peaks or the distance between the wave troughs) is h1, and d, R1, R2 and h1 satisfy: d = h1*R1 / R2. In an embodiment, h1 is 8-25 mm.

[0069] It can be understood that in other embodiments, the membrane 222 is rectangular or square, and the length of the rectangle or the side length of the square is less than the distance between the wave peaks of the adjacent two first waves 210.

[0070] In an embodiment, the size and shape of the membrane 222 on the same covered stent 100 can be different. For example, as shown in Figure 16 some of the membranes 222 have an axial length less than the distance between the wave peaks of the adjacent two first waves 210, and some of the membranes 222 extend from the first wave 210 closest to the proximal end to the first wave 210 farthest from the distal end. In an embodiment, the membrane 222 extending from the first wave 210 closest to the proximal end to the first wave 210 farthest from the distal end is located at the large bending side A and not at the small bending side B, and the membrane 222 having an axial length less than the distance between the wave peaks of the adjacent two first waves 210 is located at the small bending side B. Such distribution of the membranes 222 with different axial lengths is beneficial to avoid shortening of the windowed area 20 and extrusion of the membrane 222 located at the small bending side B by the adjacent two first waves 210, while making the bending of the covered stent 100 more smooth.

[0071] In another embodiment, other shapes of the membrane 222 can also be used, such as triangular, semicircular or square, etc. Different shapes and sizes of the membrane 222 can also be used on the same covered stent 100. For example, as shown in Figure 17 in an embodiment, the membrane 222 is triangular.

[0072] Please refer to Figure 18In an embodiment, the fenestrated zone 20 comprises a first wave 210A closest to the proximal end and a first wave 210B adjacent to the first wave 210A, and further comprises a first wave 210C and a first wave 210D sequentially located at the distal end of the first wave 210B. The membrane 222 extends along the axial direction of the fenestrated zone 20 from the first wave 210A to the first wave 210C. The membrane 222 is one or more. When the membrane 222 is one, the membrane 222 is located at the large bending side A. When the membrane 222 is more than one, one of the membranes 222 is located at the large bending side A. The length of each wave rod 211 of the first wave 210A and the first wave 210B is equal. The first wave 210C and the first wave 210D each comprise a long wave rod 211A and a short wave rod 211B. The long wave rod 211A encloses a region A1 and a region A2, which are located on both sides of the longitudinal central axis of the fenestrated zone 20, and neither of the regions A1 and A2 is located at the large bending side A. Since the blood flow direction is from the proximal end to the distal end, the region close to the proximal end is subjected to a greater blood flow impact force. The membrane 222 close to the proximal end is beneficial to avoid or slow down the shortening of this part. At the same time, compared with the rigid axial connecting member, the membrane 222 has less impact on the fenestration operation, facilitating the fenestration. At the regions A1 and A2, the long wave rod 211A has a greater length, which can provide sufficient anti-shortening ability when the covered stent 100 bends to conform to the shape of the blood vessel. That is, the membrane 222 provides anti-shortening performance in the region close to the proximal end, and the long wave rod 211A provides anti-shortening performance in the region close to the distal end, so that the fenestrated zone 20 has good anti-shortening performance. At the same time, it is easier to fenestrate at the fenestration site where the membrane 222 is located.

[0073] It can be understood that in other embodiments, when the membrane 222 is more than one, when the regions A1 and A2 exist, the membrane 222 can also not be arranged at the large bending side A. The regions A1 and A2 and the multiple membranes 222 cooperate to make the fenestrated zone 20 have anti-shortening performance, and the membrane 222 is not arranged at the large bending side A to make it easier to fenestrate at the large bending side A.

[0074] In an embodiment, regardless of whether the bottom layer film 221 is a single-layer structure or a multi-layer structure, the multiple membranes 222 are directly arranged on the outer surface or the inner surface of the bottom layer film 221.

[0075] In an embodiment, the bottom layer film 221 is a multi-layer structure, and the multiple membranes 222 are embedded inside the bottom layer film 221.

[0076] Regardless of the relative position relationship between the membrane 222 and the bottom layer film 221, or regardless of the shape and size of the membrane 222, please refer to Figure 19In an embodiment, the middle part of the diaphragm 222 is provided with a through hole 2221, which can provide a deformation space for the diaphragm 222. When the blood flow pressure is large, the diaphragm 222 can be deformed to avoid being folded.

[0077] In an embodiment, the through hole 2221 is a circular hole, and the radius of the through hole 2221 is r. The axial length of the diaphragm 222 is d, and the width is W. r, d and W satisfy: 0.25*min(d, W)≤r≤0.8*min(d, W), where min(d, W) means the smaller one of d and W. r is in the above range, so that the diaphragm 222 has both the anti-shortening performance and the anti-deformation performance.

[0078] In another embodiment, the through hole 2221 can be other shapes, such as a triangle, a semicircle, etc. When the through hole 2221 is a non-circular hole, the cross-sectional area S1 of the through hole 2221 and the area S2 of the diaphragm 222 (including the through hole 2221 part) satisfy: 0.25*S2≤S1≤0.8*S2. S1 and S2 are set according to the size relationship, so that the diaphragm 222 has both the anti-shortening performance and the anti-deformation performance.

[0079] Please refer back to Figure 1 The non-windowed area 40 includes a plurality of second wave loops 410 arranged at intervals in the axial direction and a second covering film 420 covering the plurality of second wave loops 410.

[0080] In an embodiment, the plurality of second wave loops 410 are connected by an axial connector (not shown in the figure) to make the non-windowed area 40 have the anti-shortening performance. The axial connector connects the plurality of second wave loops 410 in the axial direction to form a support framework of the non-windowed area 40.

[0081] The material of the second wave loop 410 is a material with good biocompatibility, such as nickel-titanium alloy, stainless steel, etc. In an embodiment, each second wave loop 410 includes a plurality of wave rods 411, and each wave rod 411 is connected at the head and tail to form a closed Z-shaped wave structure. In an embodiment, each second wave loop 410 includes a plurality of wave rods 411 and a plurality of arc-shaped connectors (not shown in the figure). The plurality of wave rods 411 and the plurality of arc-shaped connectors are alternately connected to form the second wave loop 410.

[0082] The material of the second covering film 420 is a material with good biocompatibility, such as e-PTFE, PET, etc. The material of the second covering film 420 is the same as or different from the material of the first covering film 220.

[0083] In an embodiment, the softness of the second covering film 420 is 1-3. Since no windowing operation is needed in the non-windowing area 40, the non-windowing area 40 can be provided with an axial connector or the like to improve the shortening resistance, and thus the second covering film 420 with a larger softness can be used to ensure the flexibility of the non-windowing area 40.

[0084] In an embodiment, the thickness of the second covering film 420 is 0.1-0.3 mm.

[0085] Please refer to Figure 1 , the covering stent 100 further comprises an anchoring area 60. The anchoring area 60 is axially connected to the end of the windowing area 20 away from the non-windowing area 40. The anchoring area 60 is used to provide anchoring performance at the proximal end. The anchoring area 60 comprises an anchoring wave 610 and a covering film 620 covering the anchoring wave 610.

[0086] The material of the anchoring wave 610 is a material with good biocompatibility, for example, nickel-titanium alloy, stainless steel, etc. The material of the covering film 620 is a material with good biocompatibility, for example, e-PTFE, PET, etc.

[0087] The anchoring wave 610 can be one or a plurality arranged in the axial direction. In an embodiment, the number of waves of the anchoring wave 610 is greater than the number of waves of the first wave 210 and the second wave 410, and the length of the wave rod of the anchoring wave 610 is less than the length of the first wave rod 211 and the second wave rod 411, so that the anchoring performance of the anchoring wave 610 is better.

[0088] In an embodiment, the covering film 620 is in an integral structure with the bottom film 221 of the first covering film 220 and the second covering film 420.

[0089] The softness of the first covering film 220 of the windowing area 20 of the above covering stent 100 is 0.3-1, so that the first covering film 220 is not prone to shortening, and thus the windowing area 20 can omit the axial connector, thereby avoiding the restriction of the axial connector on the windowing.

[0090] By reasonably setting the film sheet 222 of the first covering film 220, not only the effects of easy windowing and shortening resistance are obtained, but also the overall flexibility of the windowing area 20 is ensured to adapt to different blood vessel morphologies of different individuals.

[0091] It should be noted that when the shape and size of the bottom film 221 and the film sheet 222 are consistent, i.e., the film sheet 222 completely covers the surface of the bottom film 221, the softness of 0.3-1 above refers to the softness of the entire first covering film 220. When the film sheet 222 does not completely cover the bottom film 221, the softness of 0.3-1 refers to the softness of the area covered by the film sheet 222.

[0092] The covered stent 100 is prepared by a method known to those skilled in the art. In one embodiment, the covered stent 100 is prepared by the following method:

[0093] The metal wire is woven or cut into a desired wave shape, and then heat set. After heat setting, the anchoring wave coil 610, the first wave coil 210 and the second wave coil 410 are formed. The surfaces of the anchoring wave coil 610, the first wave coil 210 and the second wave coil 410 are covered with a film. For example, e-PTFE films can be applied to the inner and outer surfaces of the surfaces of the anchoring wave coil 610, the first wave coil 210 and the second wave coil 410. The e-PTFE film on the inner surface and the e-PTFE film on the outer surface are located between the anchoring wave coil 610, the first wave coil 210 and the second wave coil 410. When the membrane 222 is located inside the bottom film 221, the membrane 222 is located between the e-PTFE film on the inner surface and the e-PTFE film on the outer surface. When the membrane 222 is located on the surface of the bottom film 221, the membrane 222 is located on the e-PTFE film on the inner surface or the e-PTFE film on the outer surface. Then, the e-PTFE films on the inner and outer surfaces are bonded together by high temperature and pressure, and the covered stent 100 is obtained.

[0094] The technical features of the above-described embodiments can be combined in any manner. For the sake of brevity, not all possible combinations of the technical features in the above-described embodiments are described, however, as long as the combinations of the technical features do not contradict each other, they should be considered to be within the scope of the present disclosure.

[0095] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent. It should be noted that for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the scope of protection of the present application should be subject to the appended claims.

Claims

1. A covered stent, characterized by, The windowed region comprises a plurality of first wave turns arranged at intervals in the axial direction and a first film covering the plurality of first wave turns, and the softness of the first film is 0.3-1, wherein the softness is the reciprocal of the force value when a sample is pressed into a 15 cm wide gap to a depth of 10 mm using a tensile testing machine.

2. The stent graft of claim 1, wherein, The non-windowed region comprises a plurality of second wave turns arranged at intervals in the axial direction and a second film covering the plurality of second wave turns, and the softness of the first film is less than the softness of the second film.

3. The stent graft of claim 2, wherein, The thickness of the first film is greater than the thickness of the second film.

4. The stent graft of claim 1, wherein, The first film comprises a base film and a plurality of film pieces arranged on the base film, each of the film pieces is located between two adjacent first wave turns, and each of the film pieces is arranged in the circumferential direction of the windowed region.

5. The stent graft of claim 4, wherein, The distance between two adjacent first wave turns is h1, the wave height of each first wave turn is h2, the film piece is in the form of a strip, the width of the film piece is d1, and the h1, h2 and d1 satisfy: d1≤h1-h2.

6. The stent graft of claim 4, wherein, The width of the middle part of the film piece is greater than the width of the two ends of the film piece, and the middle part of the film piece is located on the large bending side of the windowed region.

7. The stent graft of claim 1, wherein, The first film comprises a base film and at least one film piece arranged on the base film, and each of the film pieces extends in the axial direction of the windowed region.

8. The stent graft of claim 7, wherein, The film piece is in the form of a strip, the width of the film piece is D, and the wave width of the first wave turn is h3, and D≤h3.

9. The stent graft of claim 7, wherein, One of the film pieces is located on the large bending side of the windowed region.

10. The stent graft of claim 7, wherein, Two of the film pieces are symmetrically arranged on both sides of the windowed region with the longitudinal center axis of the windowed region as the axis of symmetry.

11. The stent graft of claim 7, wherein, A plurality of the film pieces are arranged at intervals in the circumferential direction of the windowed region, and each of the film pieces extends in the axial direction of the windowed region.

12. The stent graft of claim 1, wherein, The first film comprises a base film and a plurality of film pieces arranged on the base film, each of the film pieces is arranged between two adjacent first wave turns, and the axial length of each of the film pieces is less than the distance between two adjacent first wave turns, a plurality of the film pieces form a row of film pieces in the axial direction of the windowed region, and a plurality of rows of the film pieces are distributed at intervals in the circumferential direction of the windowed region.

13. The stent graft of claim 1, wherein, The first film comprises a base film and at least one film piece arranged on the base film, of the plurality of first wave turns, two first wave turns close to the proximal end and two first wave turns close to the distal end are included, the film piece extends in the axial direction of the windowed region in the two first wave turns close to the proximal end, and the two first wave turns close to the distal end each comprise a long wave rod and a short wave rod.

14. The stent graft of claim 1, wherein, The first film comprises a base film and at least one film piece arranged on the base film, and a through hole is formed in the middle part of the film piece.

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