Double-layer stent and braiding method thereof

Abstract

The application relates to a double-layer stent, which comprises a braided body, the hollow column structure of the braided body is formed by interweaving the braided units arranged along a first braiding direction and the braided units arranged along a second braiding direction, the braided body is double-layered and comprises a braided outer layer and a braided inner layer, each layer is formed by interweaving the braided units of the two braiding directions, at least one braided unit of the braided outer layer is connected with at least one braided unit of the adjacent braided outer layer to form a connecting filament, the connecting filament can ensure high radial support force, high metal coverage, low shortening rate and blood flow guiding capacity, and can reduce the potential stent delamination risk of the double-layer braided stent, the braided units are rotationally interwoven at the connecting filament of the stent, the original wire pressing structure is changed, the resistance to deformation near the interlayer connecting point is increased, the braided units near the interlayer connecting point which are displaced due to friction can be quickly returned to the original positions, and the risk of stent delamination in the local part of the stent is resisted.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical devices, in particular to a double-layer stent and a weaving method thereof. BACKGROUND

[0002] Minimally invasive surgery is a common treatment for intracranial aneurysms. For intracranial aneurysms, the commonly used treatment techniques include coil embolization, covered stent implantation, stent-assisted coil embolization, and blood flow guiding device placement. For large and giant saccular aneurysms, wide-necked aneurysms, fusiform aneurysms, and dissecting aneurysms, the surgical treatment process is relatively complex, the intraoperative and postoperative complication rate is high, and the postoperative recurrence rate is high. Therefore, using the traditional coil or stent-assisted coil embolization technique for treatment has the problems of long intraoperative time, difficulty in completely occluding the aneurysm neck, and incomplete aneurysm occlusion. In most cases, the covered stent is difficult to be used in curved blood vessels, and it is difficult to be in place. It is not suitable for the siphon bend and above. After the blood flow guiding device is placed at the aneurysm neck, the blood flow in the parent artery is first changed to weaken the impact of the blood flow on the aneurysm wall. Finally, new endothelial cells are formed on the surface of the stent and at the aneurysm neck, achieving complete occlusion of the aneurysm and cure of the aneurysm and reconstruction of the parent artery. Compared with the above, the blood flow guiding device is more suitable for such conditions. The shortening of the blood flow guiding device is usually relatively long, which requires higher release positioning of the operator. The emergence of the double-layer woven stent helps to reduce the shortening of the woven stent, reduce the difficulty of release positioning of the blood flow guiding device, and shorten the operation time.

[0003] In the process of assembling, transporting and releasing the ordinary double-layer stent, external forces such as compression, pushing and stretching are often applied, which can easily cause the interlayer separation of the double-layer stent. The root cause of this phenomenon is that the woven stent is interwoven by two groups of woven wires with different rotation directions, and the two layers of the stent are not smooth planes. The displacement of the woven wires caused by the external force cannot be restored in time due to the existence of friction. At the same time, the uniformity of the stent mesh is reduced, which affects the treatment effect. SUMMARY

[0004] Therefore, the present application provides a double-layer stent and a weaving method thereof, which can avoid the interlayer separation of the double-layer stent.

[0005] According to an aspect of the present application, a double-layer stent is provided, which comprises a woven main body.

[0006] The woven main body comprises woven units arranged along a first weaving direction and woven units arranged along a second weaving direction, and the woven units of the two weaving directions are interwoven to form a hollow cylindrical structure.

[0007] The weaving unit is a single wire or multiple wires, and a spring, a strand, a rope or the like structure formed by twisting, a spring or the like before or during weaving.

[0008] The weaving body includes at least a weaving outer layer and a weaving inner layer, and each layer is interwoven by two weaving units in different weaving directions.

[0009] At least one weaving wire of the weaving inner layer is interwoven with at least one weaving wire of the weaving outer layer adjacent thereto to form a connecting strand.

[0010] In a possible implementation, in the connecting strand, the weaving unit of the weaving outer layer in the weaving strand and the weaving unit of the weaving inner layer are in the same weaving direction or different weaving directions.

[0011] In a possible implementation, the two weaving units in the connecting strand are twisted in a clockwise or counterclockwise direction to form an interlayer connecting point.

[0012] In a possible implementation, at the same axial position of the stent, the interlayer connecting points formed by at least one weaving unit of the weaving outer layer and at least one weaving unit of the weaving inner layer in the connecting strand in the circumferential direction of the stent are at least one.

[0013] In a possible implementation, at the same axial position of the stent, the interlayer connecting points are arranged along the circumferential direction of the weaving body to form an interlayer connecting strand group.

[0014] The two adjacent interlayer connecting strand groups are spaced apart by a preset distance along the axial length direction of the weaving body.

[0015] In a possible implementation, the interlayer connecting points of different interlayer connecting strand groups are distributed in the same or different circumferential positions in the axial projection of the weaving body.

[0016] In a possible implementation, the diameters of the weaving wires in the first weaving direction and the weaving wires in the second weaving direction are both in the range of 20 microns to 100 microns.

[0017] The weaving unit is made of a single material or a mixture of two or more materials, and the weaving unit is made of a material having a shape memory effect or an X-ray opaque property, or a material having both of the above two properties, such as a nickel-titanium wire, a cobalt-chromium wire, a platinum-gold wire, a nickel-titanium-platinum core wire, a cobalt-chromium-platinum core wire, and the like.

[0018] The weaving unit is made of the same material and structure, or the weaving unit is made of different materials and structures.

[0019] In one possible implementation, the two ends of the braided wire are in loose structure, partially closed structure or fully closed structure.

[0020] A braiding method using a double-layer support includes the following steps.

[0021] At the beginning of braiding or at the end of braiding, the total number of wire ends w participating in braiding is evenly divided into η groups of braided wires, and the number of wire ends in each group of braided wires is w / η, and η can be 3, 4, 6, 8, 10 or 12.

[0022] The ε groups are further evenly divided into two bundles, and ε is a natural number greater than 0 and ε≤η.

[0023] The two bundles of the braiding units are rotated in the same direction or opposite directions respectively to form stable wire bundles, and then the two bundles of wire bundles are bound together in parallel to form a wire collection group.

[0024] In one possible implementation, the end of the braiding body is sleeved with a hollow tube of noble metal that is X-ray opaque.

[0025] In one possible implementation, the end of the braiding body is fully wrapped or partially wrapped, and the adjacent braided wires with different rotation directions are wrapped groups.

[0026] The wire collection groups and the wrapped groups can be distributed in different layers.

[0027] The double-layer support of the embodiment has the following advantages: the support of the braiding body contains a special braiding structure, which greatly reduces the potential risk of delamination of the double-layer braided stent while ensuring high radial support force, high metal coverage, low shortening rate and better blood flow guiding capacity, and has certain advantages for treating hemorrhagic aneurysm disease in clinical use. Specifically, by rotating and interweaving the braided wires at the connection wire strands of the stent, the resistance to deformation near the interlayer connection points is increased. After the external force is applied, these interlayer connection points have greater rigidity, which can drive the braided wires near the interlayer connection points to quickly return to their original positions due to friction, thereby resisting the risk of stent delamination. The interlayer connection groups distributed throughout the double-layer braided stent further increase the overall resistance of the stent to delamination.

[0028] Other features and aspects of the present application will become apparent from the following detailed description of exemplary embodiments, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0029] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments, features, and aspects of the present application and serve to explain the principles of the present application.

[0030] Figure 1 A structural schematic diagram of a double-layer stent according to an embodiment of the present application is shown;

[0031] Figure 2 A cross-sectional structural schematic diagram of a double-layer stent according to an embodiment of the present application is shown;

[0032] Figure 3 (a) a schematic diagram of same-direction connected filaments, Figure 3 (b) a schematic diagram of reverse-direction connected filaments;

[0033] Figure 4 (a) a schematic diagram of different-direction connected filaments α = 180 degrees, Figure 4 (b) a schematic diagram of different-direction connected filaments α = 360 degrees;

[0034] Figure 5 (a) a schematic diagram of same-direction connected filaments α = 180 degrees, Figure 4 (b) a schematic diagram of same-direction connected filaments α = 360 degrees;

[0035] Figure 6 A structural schematic diagram of a double-layer stent according to an embodiment of the present application is shown;

[0036] Figure 7 A structural schematic diagram of a double-layer stent according to an embodiment of the present application is shown;

[0037] Figure 8 A structural schematic diagram of a double-layer stent according to an embodiment of the present application is shown;

[0038] Figure 9 A structural schematic diagram of a double-layer stent according to an embodiment of the present application is shown;

[0039] Figure 10 A structural schematic diagram of a double-layer stent according to an embodiment of the present application is shown;

[0040] Figure 11 A structural schematic diagram of a double-layer stent according to an embodiment of the present application is shown;

[0041] Figure 12 A structural schematic diagram of a double-layer stent according to an embodiment of the present application is shown;

[0042] Figure 13 A structural schematic diagram of a double-layer stent according to an embodiment of the present application is shown;

[0043] Figure 14 A structural schematic diagram of a double-layer stent according to an embodiment of the present application is shown; DETAILED DESCRIPTION

[0044] Various exemplary embodiments, features, and aspects of the present application will be described herein below with reference to the accompanying drawings. The same or similar components have the same reference numbers throughout the drawings. Although various aspects of embodiments are illustrated in the drawings, the drawings are not necessarily drawn to scale unless specifically noted.

[0045] It should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like, indicate orientations or positional relationships based on the orientations or positional relationships as shown in the drawings, and are used only for the purpose of facilitating the description of the present application or simplifying the description, and therefore cannot be construed as indicating or implying that the device or element indicated thereby must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be construed as limiting the present application.

[0046] In addition, the terms "first", "second", and the like, are used only for the purpose of description, and do not imply or imply relative importance or a specific number of the technical features indicated thereby. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified.

[0047] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations.

[0048] In addition, in order to better illustrate the present application, a large number of specific details are given in the specific embodiments below. Those skilled in the art should understand that the present application can also be implemented without some specific details. In some examples, methods, means, elements and circuits well known to those skilled in the art are not described in detail, in order to highlight the main idea of the present application.

[0049] Reference is made to Figure 1 and Figure 2The double-layer stent of the embodiment of the present application comprises a braided body 100, which comprises braided wires arranged along a first braiding direction and braided wires arranged along a second braiding direction, and the braided wires of the two braiding directions are interwoven to form a hollow column structure. The braided body 100 comprises at least a braided outer layer 110 and a braided inner layer 120, each layer is interwoven by the braided wires of the two braiding directions, at least one braided wire of the braided inner layer 120 and at least one braided wire of the braided outer layer 110 adjacent to the braided wire are interwoven to form a connecting strand, which increases the resistance to deformation near the interlayer connecting point, changes the original wire pressing structure of the stent, and improves the stability of the relative position of the two layers of the stent. The braided unit near the interlayer connecting point which is displaced due to friction can quickly return to the original position, resisting the risk of local delamination of the stent.

[0050] In the embodiment, the stent of the braided body 100 contains a special braiding structure, which greatly reduces the potential delamination risk of the double-layer braided stent while ensuring high radial support force, high metal coverage, low shortening rate and better blood flow guiding capacity. It has certain advantages for clinical use in treating hemorrhagic aneurysm disease. Specifically, by rotating and interweaving the braided wires at the connecting strand of the stent, the resistance to deformation near the interlayer connecting point 301 is increased. After external force is applied, these interlayer connecting points 301 can quickly return to their original positions due to the greater rigidity, which can drive the braided wires near the interlayer connecting points 301 to be displaced due to friction, resisting the risk of local delamination of the stent. The interlayer connecting groups distributed throughout the double-layer braided stent further increase the overall delamination resistance of the stent.

[0051] In one specific embodiment, referring to Figure 2 , the braided body 100 is a double-layer braided structure comprising a braided outer layer 110 and a braided inner layer 120. The braided inner layer 120 is provided with 2m braided wires, m braided wires for each of the twist 1 braided wire 130 and the twist 2 braided wire 140, and the braided outer layer 110 is provided with 2n braided wires, n braided wires for each of the twist 1 braided wire 130 and the twist 2 braided wire 140. The total number of braided wires w = 2(m + n), where m + n ≥ 6, and m and n are both natural numbers greater than 0.

[0052] In this specific embodiment, referring to Figure 3 and Figure 4 , the connecting strand can be a same-direction connecting strand composed of braided wires with the same twist direction, or a different-direction connecting strand composed of braided wires with different twist directions.

[0053] In one specific embodiment, referring to Figure 4 and Figure 5The two braided wires in the wire strand are interwoven in clockwise or counterclockwise direction to form an interlayer connection point 301, wherein the rotation angle a = C*180°, C is a natural number greater than 0.

[0054] In this specific embodiment, at least one outer braided wire 111 and one inner braided wire 121 are included. The braided connection mode of the outer braided wire 111 and the inner braided wire 121 includes four modes, including: opposite connection of wire strands and a = 180 degrees, opposite connection of wire strands and a = 360 degrees, same direction connection of wire strands and a = 180 degrees, and same direction connection of wire strands and a = 360 degrees. In this way, the connection mode of the outer braided wire 111 and the inner braided wire 121 can be selected according to the scene of use, while ensuring the anti-deformation ability of the braided body, and the bending can be in place.

[0055] Further, in the braided wire strand, the braided wires of the inner layer and the outer layer have the same braiding direction, the outer layer braided wire in the braided wire strand is braided along the braiding direction of the inner layer braided wire, and is braided into the braided inner layer 120, the inner layer braided wire in the braided wire strand is braided along the braiding direction of the outer layer braided wire, and is braided into the braided outer layer 110, and the number of exchanges is at least once. The angle between the braided wire braided out of the braided inner layer 120 and the braided wire braided out of the braided inner layer 120 is 20°<a<180.

[0056] In the braided wire strand, the braided wires of the inner layer and the outer layer have different braiding directions, the outer layer braided wire in the braided wire strand is braided along the braiding direction of the inner layer braided wire, and is braided into the braided inner layer 120, the inner layer braided wire in the braided wire strand is braided along the braiding direction of the outer layer braided wire, and is braided into the braided outer layer 110.

[0057] In one of the specific embodiments, refer to Figure 12 The braided pitch of the stent is P, and all the braided wires rotate 360° in the circumferential direction of the stent within one braided pitch. In the same axial position, the braided body 100 is provided with r interlayer connection points 301 in the circumferential direction, forming an interlayer connection group, wherein 1≤r≤min(m,n), and there are t interlayer connection groups in the axial direction of the stent within one pitch P. According to different operations, the distance between the interlayer connection groups in the axial direction of the stent is different, which can bring different effects. Specifically, when the distance between the adjacent two interlayer connection groups is small, the flexibility of this area is reduced, and when the distance between the adjacent two interlayer connection groups is large, the flexibility of this area is improved. Therefore, by changing the position, the number of braided wire strands formed by the braided wires of the braided outer layer and the braided inner layer of the stent, and the number of interlayer connection points 301 formed by the cross-braiding can be changed.

[0058] In this embodiment, referring to Figure 12 , the r interlayer connecting points 301 in an interlayer connecting filament group can be composed of homodromous connecting filaments or heterodromous connecting filaments, or both.

[0059] In this embodiment, the number of connecting filament points in the interlayer connecting filament groups distributed at different axial positions of the braided body 100 can be the same or different.

[0060] In this embodiment, referring to Figure 6 , Figure 7 and Figure 12 , the included angle between the braided filaments of the rotation 1 braided filament 130 and the rotation 2 braided filament 140 at the non-interlayer connecting structure 302 is 20-160°. Figure 6 , the braided filaments are staggered without overlapping each other, and the braided filaments of the braided inner layer 120 and the braided outer layer 110 have no interlayer connecting points 301, and the two-layer braided structure of the braided body 100 can be any regular braided structure such as 1-1, 1-2, 2-2, or a combination thereof.

[0061] In this embodiment, the braided filament material of the braided body 100 can be made of nickel-titanium, cobalt-chromium, or other materials with shape memory properties.

[0062] In this embodiment, the braided body 100 can be made of a platinum-gold-nickel-titanium tube or a platinum-gold-cobalt-chromium-nickel tube throughout the body to achieve the effect of being visible throughout the body.

[0063] In this embodiment, the braided body 100 can be made by mixing nickel-titanium filaments or cobalt-chromium filaments with platinum-gold filaments.

[0064] In this embodiment, referring to Figure 11 , the relationship between the number of nickel-titanium filaments or cobalt-chromium filaments x and the number of platinum-gold filaments y of the braided body 100 is x=q*y, where q is a positive integer and q≤48.

[0065] In this embodiment, the outer diameter of the braided body 100 is 1.5-7mm, and the length is 10-70mm.

[0066] In this embodiment, referring to Figure 8 , Figure 9 , Figure 10 and Figure 12 , the braided body 100 containing the interlayer connecting points 301 can have loose braided filaments at both ends, or the braided filaments can be bound together with the radiopaque hollow tube 400 to form a partially closed or fully closed structure by rewinding, welding, or mechanical pressing.

[0067] In one embodiment, referring to Figure 14 , the braided inner layer 120 is arranged to cross the braided layer 110, and the crossing point is marked by Figure 14 In one embodiment, the color depth indicates the crossing point.

[0068] In one embodiment, referring to the above, when the braided body 100 is a multi-layer structure, i.e., the number of braided layers L>2, the braided layers of different layers are Li from inside to outside, and the number of braided filaments corresponding to the braided layers of different layers are Ni, where i is a natural number greater than 0, and the total number of filaments w=∑Ni.

[0069] In this embodiment, the connecting filament of the interlayer connection point 301 can be composed of the braided filament of the innermost layer of the braided body 100 and the braided filament of the outermost layer of the braided body 100, or composed of the braided filaments of adjacent braided layers. The connecting filament can be a same-direction or opposite-direction connecting filament. In the braiding process, the two braided filaments in the connecting filament are interwoven in the clockwise or counterclockwise direction to form an interlayer connection point 301, where the rotation angle α=C*180°, and C is a natural number greater than 0.

[0070] In this embodiment, referring to Figure 13 The interlayer connection of the multi-layer braided body 100 can be a cross-layer connection, which is composed of the braided filament of the innermost layer of the braided body 100 and the braided filament of the outermost layer of the braided body 100 to form a cross-layer connection point.

[0071] In this embodiment, the interlayer connection of the multi-layer braided body 100 can be a layer-by-layer connection, which is composed of the braided filaments of adjacent braided layers to form a layer-by-layer connection. L1 and L2 form an interlayer connection point 301D1^2, L2 and L3 form an interlayer connection point 301D2^3, and so on, until the braided filament of the outermost layer of the braided body 100 participates in the interlayer connection. D1^2, D2^3, …, Di-1^i collectively constitute an interlayer connection matrix.

[0072] In this embodiment, within one braiding pitch P, all braided filaments rotate 360° along the circumference of the stent. There are r cross-layer connection points or interlayer connection matrices or their combinations arranged circumferentially on the braided body 100, which constitute an interlayer connection group, where 1≤r≤min(Ni / 2). Within one pitch P, the braided body 100 has t interlayer connection groups in the axial direction, where 1≤t≤w / 2.

[0073] In one embodiment, the braided filaments at both ends of the stent can be loose, or the braided filaments can be bound together with the radiopaque metal hollow tube to form a partially closed or fully closed structure by rewinding, welding, or mechanical pressing.

[0074] In this specific embodiment, the selection can be made by using different ways and different numbers of braiding. Specifically, when the wire heads at both ends of the stent are in a loose state, the stent can save time and labor during the manufacturing process and shorten the working hours. When the wire heads at both ends of the stent are in a winding state, there are no loose wire heads, so the inner wall of the blood vessel will not be damaged, and the blood vessel will not be stimulated. In addition, a part of the state can be loose, and a part can be winding. The welding method can directly weld the loose wire heads at both ends of the stent. The mechanical pressure holding method is similar to the welding method, and the loose wire heads at both ends of the stent can be directly fixed by pressure holding.

[0075] In this specific embodiment, the selection can be made by using different ways and different numbers of braiding. Specifically, when the wire heads at both ends of the stent are in a loose state, the stent can save time and labor during the manufacturing process and shorten the working hours. When the wire heads at both ends of the stent are in a winding state, there are no loose wire heads, so the inner wall of the blood vessel will not be damaged, and the blood vessel will not be stimulated. In addition, a part of the state can be loose, and a part can be winding. The welding method can directly weld the loose wire heads at both ends of the stent. The mechanical pressure holding method is similar to the welding method, and the loose wire heads at both ends of the stent can be directly fixed by pressure holding.

[0076] A braiding method for binding the two layers of the end of the braiding body 100 together by full closed wire collection or partial closed wire collection, comprising the following steps:

[0077] S100, when starting braiding or ending braiding, the total wire heads w participating in braiding are first divided into η braiding wire groups, and the number of wire heads in each braiding wire group is w / η, η can be 3, 4, 6, 8, 10, 12;

[0078] S200, further divide ε groups into two bundles, ε is a natural number greater than 0, and ε≤η;

[0079] S300, the two divided bundles of the braiding wire rotate in the same direction or opposite directions to form stable wire bundles, and then the two wire bundles are bound together in parallel to form a wire collection group.

[0080] In one embodiment, the wire collection groups of the braided body 100 can be fixed by welding, including but not limited to: 1, welding the end of the inner and outer layers of the braided body 100, 2, welding the end of the inner and outer layers of the braided body 100.

[0081] In one embodiment, the end of the braided body 100 contains a hollow tube 400 of X-ray opaque noble metal, the number of which is ε, and the hollow tube 400 can be connected to the braided wire by adhesion, welding or mechanical pressure.

[0082] In one embodiment, the end of the braided body 100 can be designed with a full or partial wrap structure, dividing the w braided wires into w / 2 groups, and the two adjacent braided wires with inconsistent rotation directions are the wrap groups.

[0083] In one embodiment, the wire collection groups and the wrap groups can be staggered.

[0084] In summary, during the braiding process of the double-layer stent, one braided wire is selected from each of the two layers of the braided body 100 to form a braided strand, and the two braided wires in the braided strand are rotated by 180° of an integer multiple to form an interlayer connection point 301 during the braiding process. The interlayer connection points 301 located at the same circumferential height of the braided body 100 form an interlayer connection group, and a plurality of same or different interlayer connection groups are distributed along the axial direction of the braided body 100, and the interlayer connection points 301 are distributed in the non-interlayer connection structure.

[0085] Embodiment 1

[0086] The double-layer braided body 100 mentioned in the present application is a full-wire collection closed structure, in which the number of braided inner layer 120 and braided outer layer 110 wires is the same, each interlayer connection group has 6 different connection strands, and all braided wires are nickel-titanium-platinum core braided wires that can be developed throughout the body.

[0087] Embodiment 2

[0088] The two ends of the braided body 100 respectively include a certain number of tapered rings, the ends of the rings contain hollow tubes 400 that can locate the position of the stent and are X-ray opaque, and contain two connection wire groups, which are arranged along the axial direction of the stent.

[0089] Embodiment 3

[0090] The braided wire at one end of the braided body 100 is a closed structure formed by back winding, the radiopaque metal hollow tube 400 is sleeved on the braided wire at the back winding position, and the other end of the braided body 100 is connected with the radiopaque metal hollow tube 400 by welding or mechanical pressing, and the stent comprises two kinds of connecting wire groups, and the interlayer connecting points 301 of the two kinds of connecting wire groups are arranged in the axial direction of the stent.

[0091] The above has described the embodiments of the present application, the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles, practical application or improvement of the technology in the market of the embodiments, or to enable other ordinary skilled in the art to understand the embodiments disclosed herein.

Claims

1. A double-layer stent, characterized in that: Includes: braided main body; The braided body comprises braiding units arranged along a first braiding direction and braiding units arranged along a second braiding direction. The braiding units in the two braiding directions are interwoven to form a hollow cylindrical structure, and the angle formed in the axial direction of the stent is within the range of 20 degrees to 180 degrees. The braiding unit is a single wire or multiple wires, which are twisted or wound in advance or during the braiding process to form a spring, strand and / or rope structure; The braided main body comprises at least a braided outer layer and a braided inner layer, each layer being interwoven by braided units in two braiding directions; At least one braiding unit of the braided inner layer is cross-woven with at least one braiding unit of the adjacent braided outer layer to form a connecting strand; In the connecting strands, the braiding units of the braided outer layer in the braided main body and the braiding units of the braided inner layer have the same braiding direction or different braiding directions; The two braiding units in the connecting strand are woven in a clockwise or counterclockwise direction to form an interlayer connection point; The rotation angle α=C*180°, C is a natural number greater than 0; At the same axial position of the stent, there is at least one connecting wire strand in the circumferential direction of the stent, forming an interlayer connection point.

2. The double-layer stent according to claim 1, characterized in that: The wire diameters of the braiding units along the first braiding direction and the braiding units along the second braiding direction are both within a range of 20 micrometers to 100 micrometers.

3. The double-layer stent according to claim 1, characterized in that: The braided unit is made of a single material or a mixture of two or more materials; the material has a shape memory effect or is opaque to X-rays, or has both of the above characteristics.

4. The double-layer stent according to claim 3, characterized in that: The stent is woven from the braiding units of the same material and structure, or is woven from a mixture of the braiding units of different materials and structures.

5. The double-layer stent according to claim 1, characterized in that: The two ends of the braided wires of the connecting wire strands are loose structures, partially closed wire structures or fully closed wire structures.

6. The double-layer stent according to claim 1, characterized in that: The double-layer stent is woven by the following steps: When weaving starts or ends, the total yarn heads w of the weaving units involved in weaving are first divided into braided wire groups, the number of wire heads in each braided wire group is w / , 3, 4, 6, 8, 10 or 12; The ɛ group is further divided into two bundles, where ɛ is a natural number greater than 0, and ɛ≦ ; The two equally divided weaving units rotate in the same direction or in opposite directions to form a stable yarn bundle, and then the two yarn bundles are bound together in parallel to form a yarn collection group.

7. The double-layer stent according to claim 6, characterized in that: The end of the braided body is sleeved with a noble metal hollow tube that is opaque to X-rays.

8. The double-layer stent according to claim 7, characterized in that: The ends of the braided body are fully or partially wound, and the adjacent braided wires with different rotation directions form a winding group; The wire collecting group and the rewinding group are both distributed in staggered layers.

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