Knitted covered stent

Abstract

The application relates to a knitted film-covered stent, which comprises a support layer and a flow resistance layer, the support layer is knitted by knitting units and has a hollow column-shaped knitting structure, and the flow resistance layer is knitted by knitting units, wherein the support layer serves as the basic framework of the stent and provides necessary mechanical support, the flow resistance layer is a knitting structure covering the outside of the support layer, the flow resistance layer adopts a knitting process to make the knitting units pass through the loops and continuously knit into a net to cover the outside of the support layer, the inner side of the flow resistance layer is attached to the outer side of the support layer, a knitted film-covered stent with a knitting structure + a knitting structure is obtained, and the support layer and the flow resistance layer have interlayer connecting structures to realize the interlayer connecting and fixing of the support layer and the flow resistance layer, compared with a traditional cutting framework + polymer film design, the knitted film-covered stent has more excellent wall adhesion and compliance and can better adapt to the shape and changes of blood vessels, thereby improving the implantation effect and treatment effect of the stent.

Description

TECHNICAL FIELD

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

[0002] Minimally invasive interventional surgery is a common treatment for intracranial aneurysms. For the treatment of intracranial aneurysms, the commonly used techniques include spring coil filling, stent-assisted spring coil filling, blood flow guiding device placement, covered stent implantation and other methods. For large and giant cystic aneurysms, wide-necked aneurysms, fusiform and dissecting aneurysms, if traditional spring coil or stent-assisted spring coil filling technology is used, there are problems such as long time during operation, incomplete aneurysm occlusion, high postoperative complication rate, and so on. Due to its high weaving density, the blood flow guiding device also has the problems of incomplete adhesion and bending flexibility, which may affect the postoperative aneurysm occlusion rate and ischemic complications. SUMMARY

[0003] Therefore, the present application provides a knitted covered stent.

[0004] According to an aspect of the present application, a knitted covered stent is provided, comprising: a support layer and a flow resistance layer,

[0005] The support layer is woven by weaving units and has a hollow cylindrical woven structure.

[0006] The flow resistance layer is a knitted structure in which the weaving units are continuously knitted into a net by being looped and sleeved through the knitting process and covering the outside of the support layer. The inner side of the flow resistance layer is attached to the outer side of the support layer, and there is an interlayer connection structure between the support layer and the flow resistance layer, which realizes the interlayer connection and fixation of the support layer and the flow resistance layer.

[0007] In one possible implementation, at least one metal weaving unit of the support layer is inserted out of the woven structure of the flow resistance layer along the knitting mesh, and then inserted into the woven structure of the flow resistance layer along the knitting mesh, forming the interlayer connection structure of the support layer and the flow resistance layer.

[0008] In one possible implementation, the weaving units of the support layer and the weaving units of the flow resistance layer are connected together by a metal ring between the support layer and the flow resistance layer, forming the interlayer connection structure of the support layer and the flow resistance layer.

[0009] In one possible implementation, there is an interlayer connection structure between the support layer and the flow resistance layer.

[0010] The interlayer connection structure is multiple and uniformly arranged along the circumference and axis of the knitted covered stent.

[0011] In one possible implementation, the support layer comprises braiding units arranged along a first braiding direction and braiding units arranged along a second braiding direction, the braiding units of the two braiding directions being interwoven to form a hollow cylindrical structure.

[0012] In one possible implementation, the braiding manner of the flow resistance layer is a warp knitting or weft knitting process.

[0013] In one possible implementation, the length of the support layer in the axial direction of the stent is greater than the length of the flow resistance layer in the axial direction of the stent.

[0014] In one possible implementation, the outer diameter of the support layer is smaller than the outer diameter of the flow resistance layer.

[0015] In one possible implementation, the number of filaments of the braiding units of the support layer is 2m, and 4≤m≤48.

[0016] The number of filaments of the braiding units of the flow resistance layer is n, and n≥1.

[0017] In one possible implementation, the arrangement frequency of the interlayer connection structure in the circumferential direction of the stent is a, and 1≤a≤2m.

[0018] The arrangement frequency of the interlayer connection structure in the axial direction of the stent is b, and b=x*p, p is the pitch of the braiding layer, and x>0.

[0019] In one possible implementation, the metal coverage of the knitted stent support layer is in the range of 10-40%.

[0020] The mesh size of the flow resistance layer is in the range of 20-200 microns.

[0021] In one possible implementation, a metal ring is arranged between the braiding units of the support layer and the braiding units of the flow resistance layer.

[0022] The metal ring is a hollow tubular structure or a C-shaped tubular structure, and the braiding units of the support layer and the flow resistance layer are fixed together at the interlayer connection structure.

[0023] In one possible implementation, the cross section of the braiding unit includes, but is not limited to, a circular shape, a triangular shape, and a hollow ring shape, and the like.

[0024] In one possible implementation, the braiding unit is made of a shape memory material such as nickel-titanium or cobalt-chromium, or a DFT material containing a radiopaque component, or a shape memory material such as nickel-titanium or cobalt-chromium and a radiopaque material such as platinum-tungsten or platinum-iridium, alone or in combination.

[0025] In one possible implementation, the outer diameter of the stent ranges from 1.5 mm to 12 mm, and the length ranges from 10 mm to 80 mm.

[0026] In one possible implementation, the total number of the knitting yarns w is evenly divided into η knitting yarn groups when the knitting starts or ends, and the number of the yarns in each knitting yarn group is w / η, and η can be 3, 4, 6, 8, 10, or 12.

[0027] The ε groups are further evenly divided into two bundles, and ε is a natural number greater than 0 and ε≤η; the two bundles are rotated in the same direction or opposite directions to form stable yarn bundles, and the two bundles are bound together in parallel to form a closed yarn group.

[0028] In one possible implementation, the end of the support layer is in a partially closed structure, a fully closed structure, or a loose structure.

[0029] The end of the support layer can be fixed by winding, bundle division, welding, or adhesion to form a partially closed or fully closed structure.

[0030] In one possible implementation, the knitting unit of the support layer and the flow resistance layer is in one yarn diameter or a plurality of yarn diameters.

[0031] The yarn diameter of the knitting unit ranges from 0.0005 inch to 0.005 inch.

[0032] The yarn diameter of the knitting unit of the support layer is greater than or equal to the yarn diameter of the knitting unit of the flow resistance layer.

[0033] A method for manufacturing a knitted stent, for manufacturing a knitted stent, comprising the following steps:

[0034] The knitting unit is used to knit the support layer by a knitting process.

[0035] The flow resistance layer is knitted along the outer surface of the support layer by a knitting process, and the knitting unit is regularly inserted into the support layer during the knitting process to obtain the flow resistance layer, thereby forming a knitted stent with interlayer connection.

[0036] The knitted stent is subjected to heat treatment for shaping.

[0037] The knitted covered stent has the following beneficial effects: the support layer is used as a core carrier, and the flow resistance layer is used as a film layer. The knitting units of the support layer are inserted into and outside the flow resistance layer to form an interlayer connection structure, or the knitting units of the support layer and the flow resistance layer are connected by hollow tubular or C-shaped tubular metal rings to form an interlayer connection structure, so that the support layer 120 and the flow resistance layer 110 are fixedly connected in layers. Alternatively, welding, leaching or gluing is directly used to form an interlayer connection structure, so that the support layer and the flow resistance layer are tightly and firmly connected at some positions. In this way, the problem of separation between layers of the stent during use can be prevented, so that the long-term stability and reliability of the stent are ensured. Compared with the traditional covered stent, the flow resistance layer as the film layer in the application does not exist as a thin film without mechanical properties. The flow resistance layer and the support layer are both made of knitting units with shape memory effect. In addition, the support layer is knitted, and the flow resistance layer is knitted, so that a knitted structure + knitted structure covered stent is obtained. Compared with the traditional cutting skeleton + polymer film design, the covered stent has better adhesion and compliance, and can better adapt to the shape and changes of the blood vessel, so that the implantation effect and treatment effect of the stent are improved.

[0038] 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

[0039] 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.

[0040] Figure 1 A schematic diagram showing the main structure of the knitted covered stent according to the embodiments of the present application is shown in FIG. 1.

[0041] Figure 2 A schematic diagram showing the interlayer connection structure of the knitted covered stent according to the embodiments of the present application is shown in FIG. 2.

[0042] Figure 3 Another schematic diagram showing the interlayer connection structure of the knitted covered stent according to the embodiments of the present application is shown in FIG. 3.

[0043] Figure 4 A schematic diagram showing the interlayer connection structure of the support layer of the knitted covered stent according to the embodiments of the present application is shown in FIG. 4.

[0044] Figure 5 A schematic diagram showing the weft knitting structure of the flow resistance layer of the knitted covered stent according to the embodiments of the present application is shown in FIG. 5.

[0045] Figure 6 A schematic diagram showing the warp knitting structure of the flow resistance layer of the knitted covered stent according to the embodiments of the present application is shown in FIG. 6.

[0046] Figure 7 A schematic diagram of a cross-section structure of a metal ring connecting a support layer and a flow resistance layer to form an interlayer connection structure of the embodiment of the present application is shown.

[0047] Figure 8 A schematic diagram of an overall effect of a support of the embodiment of the present application connecting a support layer and a flow resistance layer to form an interlayer connection structure is shown.

[0048] Figure 9 A schematic diagram of a closed wire collecting group structure of a knitted covered stent of the embodiment of the present application is shown.

[0049] Figure 10 A schematic diagram of a fixing method of a closed wire collecting group structure of a knitted covered stent of the embodiment of the present application is shown.

[0050] Figure 11 A schematic diagram of a structure of a support layer end portion bundle tailing of the embodiment of the present application is shown.

[0051] Figure 12 A schematic diagram of a structure of a support layer end portion bundle tailing and end portion end winding staggered arrangement of the embodiment of the present application is shown.

[0052] Figure 13 A schematic diagram of a structure of a support layer end portion bundle tailing and end portion end winding staggered arrangement of the embodiment of the present application is shown.

[0053] Figure 14 A schematic diagram of a structure of a flow resistance layer end portion loose wire head connecting and fixing of the embodiment of the present application is shown. DETAILED DESCRIPTION

[0054] Various exemplary embodiments, features and aspects of the present application will be described in detail below with reference to the accompanying drawings. The same reference numbers in the drawings indicate functionally similar or identical elements. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

[0055] It should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application or simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0056] In addition, the terms "first", "second", etc. are used herein only to describe different instances, and cannot be construed as indicating or implying relative importance or a specific number of the technical features indicated. Thus, 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 and specifically limited.

[0057] 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.

[0058] 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 ideas of the present application.

[0059] As shown in Figure 1 The knitted stent 10 of the present application comprises a support layer 120 and a resistance layer 110. The support layer 120 is knitted by knitting units and has a hollow cylindrical knitting structure. The resistance layer 110 is knitted by knitting units. The support layer 120 serves as the basic framework of the stent 10 and provides necessary mechanical support. The resistance layer 110 is a knitted structure covering the outside of the support layer 120. The resistance layer 110 is knitted by a more delicate knitting process to cover the outside of the support layer 120. The inner side of the resistance layer 110 is attached to the outer side of the support layer 120. There is an interlayer connection structure between the support layer and the resistance layer. The knitting units of the support layer 120 are inserted into the resistance layer 110 to form the interlayer connection structure, thereby realizing the interlayer connection and fixation of the support layer 120 and the resistance layer 110.

[0060] In this embodiment, the knitted covered stent 10 in the application takes the support layer 120 as the core carrier, and the flow resistance layer 110 as the covered layer. The knitting units of the support layer 120 are inserted into and outside the flow resistance layer 110 to form an interlayer connection structure, or a hollow tubular or C-shaped tubular metal ring is used to connect the knitting units of the support layer and the flow resistance layer to form an interlayer connection structure, so as to realize the interlayer connection and fixation of the support layer 120 and the flow resistance layer 110. Alternatively, welding, leaching or gluing is directly used to realize the close and firm connection of the support layer 120 and the flow resistance layer 110 at some positions. In this way, the problem of interlayer separation of the stent 10 during use can be prevented, so as to ensure the long-term stability and reliability of the stent 10. Compared with the traditional covered stent 10, the flow resistance layer 110 as the covered layer in the application does not exist merely as a thin film without mechanical properties. The flow resistance layer 110 and the support layer 120 are both made of knitting units with shape memory effect. In addition, the support layer 120 is knitted, and the flow resistance layer 110 is knitted, so as to obtain a knitted covered stent 10 with a knitted structure and a knitted structure. Compared with the traditional design of a cut skeleton and a polymer film, the knitted covered stent 10 exhibits more excellent conformability and adaptability, and can better adapt to the shape and changes of the blood vessel, thereby improving the implantation effect and treatment effect of the stent 10.

[0061] Further, compared with the traditional polymer film, the application of the knitted structure as the covered layer has greater flexibility and adaptability. By skillfully combining knitting loops of different sizes, especially by designing large knitting loops at the covered branch blood vessels, the problem of occlusion of the branch blood vessels can be effectively avoided.

[0062] In a specific embodiment, at least one knitting unit of the support layer 120 is inserted out of the knitting structure of the flow resistance layer 110 along the knitting mesh, and then inserted into the knitting structure of the flow resistance layer 110 along the knitting mesh, so as to form an interlayer connection structure of the support layer 120 and the flow resistance layer 110. By inserting the knitting units of the support layer 120 into and outside the flow resistance layer 110 at some positions of the stent 10, the resistance to deformation of the interlayer connection structure 200 is increased. After the external force is applied, due to the mutual nesting between the flow resistance layer 110 and the support layer 120 near the interlayer connection structure 200, the risk of interlayer separation caused by the difference in deformation recovery ability between the flow resistance layer 110 and the support layer 120 after the external force is released is avoided. Even if the flow resistance layer 110 and the support layer 120 produce a certain displacement when the external force is applied, the flow resistance layer 110 can be quickly restored to the original position under the driving of the support layer 120 with relatively large rigidity, so as to further resist the risk of local delamination of the stent 10. The interlayer connection structures 200 distributed at various positions of the stent 10 further increase the overall resistance to delamination of the stent 10.

[0063] Further, in this specific embodiment, the support layer 120 and the flow blocking layer 110 are connected by a plurality of interlayer connection structures 200, which are uniformly arranged along the circumferential and axial directions of the stent 10. Specifically, the plurality of interlayer connection structures are uniformly arranged along the circumferential and axial directions of the stent 10, which ensures the stability and uniformity of the stent 10 in the overall structure, thereby enhancing the mechanical strength of the stent 10, making it better able to withstand forces from all directions, and also improving the durability and reliability of the stent 10.

[0064] Further, by the interlaced units of the support layer 120 penetrating in and out of the flow blocking layer 110, the interlaced units of the support layer are partially interlaced across layers, and the support layer 120 and the flow blocking layer 110 are nested with each other, connecting the interlaced layer and the knitted layer together, which can avoid the separation between the two layers of the stent 10 during use.

[0065] In a specific embodiment, the support layer 120 comprises interlaced units arranged along a first interlacing direction and interlaced units arranged along a second interlacing direction, and the interlaced units along the two interlacing directions are interlaced to form a hollow cylindrical structure. By arranging the metal interlaced units along the first interlacing direction and the second interlacing direction to form the support layer 120, and by arranging two or more metal interlaced wires in the clockwise or counterclockwise interlaced unit, the metal interlaced wire stock formed by the clockwise or counterclockwise interlaced unit has better flexibility and better ability to resist local collapse of the stent compared to the metal interlaced wire stock prepared by a single interlaced unit in a conventional manner.

[0066] Further, in this specific embodiment, as shown in Figure 4 (a), the interlaced units 121 arranged along the first interlacing direction and the interlaced units 122 arranged along the second interlacing direction of the support layer 120 penetrate out of the flow blocking layer 110 along the knitted mesh holes of the flow blocking layer 110, then form a special Hock structure 130 in the process of continuous interlacing, and finally penetrate into the flow blocking layer 110 along the knitted mesh holes of the flow blocking layer 110, forming the interlayer connection structure with special structure of the support layer.

[0067] The interlaced structure of the support layer includes but is not limited to regular interlaced structures such as 1-1 interlacing, spring interlacing, interlocking structure (such as Figure 4 (b)), Hock structure, etc.

[0068] Among them, as shown in Figure 2As shown, the weaving units of the support layer 120 are composed of two parallel weaving wires, and the support layer adopts a 1-on-1 weaving structure: the intersections formed by the weaving units of the support layer 120 and the weaving units of another weaving direction are located on the opposite side of this weaving unit due to the interweaving. The opposite side here can be understood as two adjacent intersections formed by interweaving with the weaving units of another weaving direction on a weaving unit, one of which is overlapped on the inner side of this weaving unit, and the other is overlapped on the outer side of this weaving unit, that is, the weaving units in different directions are interwoven with each other in a "1-on-1" pattern.

[0069] Among them, such as Figure 3 As shown, the spring weaving method is as follows: the support layer is woven by weaving units arranged along the first weaving direction and the second weaving direction, and the weaving units in at least one direction are woven strands formed by twisting two or more weaving wires. The woven strands can be formed before weaving or during the weaving process. The woven strands twisted during the weaving process specifically refer to: multiple weaving units in the same direction are first twisted with each other, that is, twisted to a certain extent to form a weaving unit woven strand, and then interwoven with the weaving unit woven strand in the other direction to form the support layer 120. Specifically, the weaving units in the woven strands are twisted with each other clockwise or counterclockwise to form woven strands, so that the flexibility of the support layer 120 woven by the woven strands is improved, and at the same time, it has a better ability to resist local collapse of the stent.

[0070] In a specific embodiment, if Figure 5 and Figure 6 As shown, the weaving method of the flow-blocking layer 110 includes warp knitting or weft knitting. The main advantages of warp knitting include: good warp dimensional stability. The warp knitted flow-blocking layer 110 is made up of one or more groups of parallel weaving units that are woven into loops along the axial direction of the stent and interwoven with each other, which makes its warp dimensional stability very stable, soft in texture, and has good shape retention. The main advantages of weft knitting include: good weft elasticity. The flow-blocking layer 110 is made up of one or more groups of parallel weaving units that are woven into loops along the axial direction of the stent and interwoven with each other, which makes its stent circumferential elasticity very good, suitable for making a flow-blocking layer 110 that requires greater stretchability.

[0071] In a specific embodiment, the axial length of the support layer 120 in the stent 10 is greater than the axial length of the flow-blocking layer 110 in the stent 10. The support layer 120 and the flow-blocking layer 110 are both hollow cylindrical structures. Since the flow-blocking layer 110 is coaxially arranged on the support layer 120, the longer axial length of the support layer 120 can provide a wider support range, ensuring that the stent 10 can firmly adhere to and support the blood vessel wall after implantation, especially at the bends or branches of the blood vessels, thereby enhancing the adaptability and stability of the stent 10 and effectively blocking or regulating blood flow without sacrificing the overall structural integrity of the stent 10.

[0072] Further, the difference in axial length between the support layer 120 and the flow blocking layer 110, through the structural design of the end of the support layer 120, such as the end of the trumpet structure, helps the stent 10 to better anchor in the lesion site during the implantation process, better adapt to the changes of the blood vessel, reduce the difficulty of implantation, and improve the success rate of the operation.

[0073] In the embodiment, the outer diameter of the support layer 120 is smaller than the outer diameter of the flow blocking layer 110.

[0074] In a specific embodiment, the number of support layers 120 is 2m, 4≤m≤48, and the number of flow blocking layers 110 is n, n≥1.

[0075] In a specific embodiment, the arrangement frequency of the interlayer connection structure 200 in the circumferential direction of the stent 10 is a, 1≤a≤2m, and the arrangement frequency of the interlayer connection structure 200 in the axial direction of the stent 10 is b, b=x*p, p is the pitch of the woven layer, x>0.

[0076] In a specific embodiment, the metal coverage of the support layer 120 of the stent 10 is in the range of 10-40%, and the mesh size of the flow blocking layer 110 is in the range of 20 microns-200 microns. After the support layer 120 reaches the lesion site, the area covered by the woven unit of the support layer 120 is controlled within a certain range, i.e. between 10% and 40%, which can provide sufficient mechanical support, while the flow blocking layer 110 has enough space to play its role of blocking blood flow or other specific functions, and the balance between the two. The mesh size of the flow blocking layer 110 is set in the range of 20 microns to 200 microns, which ensures that the flow blocking layer 110 can effectively block or regulate blood flow, and also allows necessary fluid to pass through to maintain the normal physiological function of the blood vessel. Appropriate mesh size helps to reduce the stimulation of the stent 10 to the blood vessel wall, reduces the risk of inflammation, and promotes the recovery of the patient.

[0077] In a specific embodiment, a metal ring is provided between the support layer 120 and the flow blocking layer 110, which is a hollow tubular structure or a C-shaped tube, wrapped around the outside of the adjacent woven units of the support layer 120 and the flow blocking layer 110 to form an interlayer connection structure. The metal ring connects the support layer 120 and the flow blocking layer 110 together to avoid the separation between the two layers during use.

[0078] Further, the metal ring with a hollow structure is a cylindrical structure with an open end inside, which is wrapped around the outside of the woven units of the support layer 120 and the flow blocking layer 110 by using a dispensing fixing method.

[0079] In the embodiment, the metal ring is a hollow structure with an open end inside, which is wrapped around the outside of the woven units of the support layer 120 and the flow blocking layer 110 by using a dispensing fixing method. Figure 7As shown, the hollow cylindrical metal ring is a hollow cylinder structure with open ends, and the cross section is circular. The C-shaped metal ring is a hollow cylinder structure with open ends, and the cross section is a "C" structure. The metal ring can be directly clamped and covered outside the woven unit of the support layer 120 and the flow resistance layer 110. The tight wrapping not only enhances the strength of the connection point, but also effectively prevents the separation phenomenon between the layers that may occur during use, thereby greatly improving the reliability and safety of the stent 10. The metal ring firmly connects the support layer 120 and the flow resistance layer 110 together, and the interlayer connection structure formed by arranging the metal ring in a certain pattern in the circumferential and axial directions of the stent is not only durable, but also can evenly distribute stress, avoiding damage to the stent 10 caused by local stress concentration. Whether in a complex blood vessel environment or in a long-term use process, it provides continuous and stable support and treatment for patients.

[0080] In a specific embodiment, the woven unit is made of nickel-titanium, cobalt-chromium, or other materials with shape memory properties, or DFT materials containing radiopaque components, or nickel-titanium, cobalt-chromium, and other shape memory materials mixed with platinum-tungsten, platinum-iridium, and other radiopaque materials.

[0081] In a specific embodiment, as shown, the outer diameter of the covered stent 10 is in the range of 1.5-12 mm, and the length is in the range of 10-80 mm. Figure 8

[0082] In a specific embodiment, the woven unit of the support layer 120 and the flow resistance layer 110 is a single wire diameter or a mixture of multiple wire diameters. The wire diameter of the woven unit is in the range of 0.0005 inches to 0.00 inches. The wire diameter of the woven unit of the support layer 120 is greater than or equal to the wire diameter of the woven unit of the flow resistance layer 110.

[0083] In a specific embodiment, as shown, Figure 8 The main body of the support layer 120 of the knitted covered stent 10 is a flat section structure, and the axial ends of the support layer 120 are flared structures, which improve the opening ability and anchoring ability of the stent 10. The support layer 120 with flared structures not only gives the stent 10 stronger expansion ability in the end region, but also makes the stent 10 easier to open and fit the blood vessel wall during implantation, thereby effectively reducing the difficulty of implantation and the risk of complications. At the same time, the flared structure also significantly improves the anchoring performance of the stent 10, ensuring that the stent 10 can be firmly fixed at the desired position, avoiding potential problems such as displacement or shedding, and further enhancing the safety and reliability of treatment.

[0084] Further, the interlayer connection structure of the support layer 120 and the flow resistance layer 110 is formed by fixing the adjacent woven units of the support layer 120 and the flow resistance layer 110 together by a metal ring.​

[0085] Further, the end of the support layer 120 of the knitted covered stent 10 can be a closed structure formed by looping back, splitting the wire bundle, or binding the loose wire bundle together by mechanical clamping, welding, bonding, cylindrical hollow tube or C-shaped ring, etc.

[0086] Wherein, the two ends of the support layer 120 can be bound together by full-closed wire collection or partial-closed wire collection. The full-closed wire collection technology is that when starting or ending knitting, the total wire head w participating in knitting is first divided into η knitting unit groups, and the number of wire heads in each knitting unit group is w / η, η can be 3, 4, 6, 8, 10, 12; Further, ε groups are further divided into two bundles, ε is a natural number greater than 0, ε≤η; The two bundles are self-rotated in the same direction or opposite direction to form stable wire bundles, and then the two wire bundles are bound together in parallel to form a closed wire collection group, and the closed wire collection group is characterized as follows Figure 9 As shown, fixed together by dispensing, welding, etc. (a metal ring can be provided outside to avoid insufficient bonding or welding firmness). The support layer 120 of the knitted covered stent 10 has a partial-closed structure, a full-closed structure or a loose structure at the end, and the closed structure can be achieved by looping back, splitting the wire bundle, welding, bonding, etc. The looping back and the end collection structure can be sleeved between the loops at the end of the knitting layer, and the axial schematic diagram of the support layer 120 splitting the wire bundle and the end collection is as shown in Figure 11 and Figure 12 Based on the above, the partial-closed or full-closed structure formed by splitting the wire bundle and looping back can have flush ends or staggered arrangement, and the staggered arrangement effect is as shown in Figure 13 The end of the support layer 120 of the knitted covered stent 10 can be a closed structure formed by looping back, splitting the wire bundle, or binding the loose wire bundle together by mechanical clamping, welding, bonding, cylindrical hollow tube or C-shaped ring, etc. Figure 14 In addition, in order to further enhance the stability and reliability of the connection, hollow rings, C-shaped rings and various special-shaped rings and other auxiliary elements can also be used, which can ensure that the knitting wire heads of the resistance layer 110 and the support structure are firmly and closely connected, improve the overall performance of the stent 10, and also ensure its stability and durability in complex environments. Figure 7

[0087] ​According to the above, the total number of yarns w participating in the knitting is first divided into η groups of knitting units when starting or ending the knitting, and the number of yarns in each group of knitting units is w / η, and η can be 3, 4, 6, 8, 10, or 12. Further, ε groups are further divided into two bundles, and ε is a natural number greater than 0 and ε≤η. The two bundles of the knitting units are rotated in the same direction or opposite directions to form stable yarn bundles, and then the two bundles are bundled together in parallel to form a yarn collection group.

[0088] In one embodiment, the yarn collection group of the support layer 120 can be fixed by welding.

[0089] In one embodiment, the end of the support layer 120 contains ε X-ray opaque hollow tubes of noble metal, which are connected to the knitting units by adhesion, welding, or mechanical pressing.

[0090] In one embodiment, the end of the support layer 120 can be designed with a full or partial wrap structure, dividing the w knitting units into w / 2 groups, and the two adjacent knitting units with inconsistent rotation directions are wrap groups.

[0091] In one embodiment, the yarn collection group and the wrap group can be distributed in different layers.

[0092] In one embodiment, the resistance layer 110 of the knitted covered stent 10 is designed as Figure 14 The loose yarns at the end can be fixed by glueing, welding, or wrapped around the knitting yarns of the support layer 120. In addition, to further enhance the stability and reliability of the connection, hollow rings, C-rings, and various shaped rings and other auxiliary elements can be used, which are moderately extruded by external force, mechanically clamped, or supplemented by advanced technology such as glueing and welding. Figure 7 This can ensure a firm and tight connection between the knitted yarns of the resistance layer 110 and the support structure, improve the overall performance of the stent 10, and ensure its stability and durability in complex environments.

[0093] A preparation method for preparing a covered stent, comprising the following steps:

[0094] S100, using the knitting units to knit the support layer 120 by knitting technology;

[0095] In this step, high-quality knitting units are used as raw materials to construct the support layer 120 of the stent 10 by knitting technology. The support layer 120 provides the necessary strength and stability to ensure the reliability and durability of the stent 10 in complex environments.

[0096] S200, using the knitting unit along the outer surface of the support layer 120, knitting the flow resistance layer by the knitting process, and regularly knitting the knitting unit into the support layer 120 during the knitting process to obtain the flow resistance layer 110 and form the knitted covered stent 10 with interlayer connection;

[0097] In this step, the knitting unit of the flow resistance layer 110 is tightly fixed on the support layer 120 by regularly knitting the knitting unit into the support layer 120 on the outer surface of the support layer 120, and the knitted covered stent 10 with interlayer connection is obtained.

[0098] S300, heat treating and shaping the knitted covered stent 10;

[0099] In this step, the knitted covered stent 10 is heat treated and shaped to eliminate internal stress that may be generated during knitting and knitting, make the structure of the stent 10 more stable, and also enhance the strength and toughness of the knitting unit, improve the durability and service life of the stent 10. Importantly, by accurately controlling the temperature and time of heat treatment, it can be ensured that the stent 10 maintains its original shape and size after shaping.

[0100] 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 terms used herein is intended to best explain the principles, practical application or improvement of technology in the market of the embodiments, or to enable other ordinary skilled persons in the art to understand the embodiments disclosed herein.

Claims

1. A knitted stent graft, characterized in that: include: Support layer and flow barrier layer, The support layer is woven from weaving units and has a hollow cylindrical weaving structure; The flow-blocking layer is a knitted structure in which the knitting units are knitted into loops and continuously woven into a mesh through a knitting process, and the knitted structure covers the outside of the support layer. The inner side of the flow-blocking layer is attached to the outer side of the support layer, and an interlayer connection structure exists between the support layer and the flow-blocking layer, thereby achieving interlayer connection and fixation between the support layer and the flow-blocking layer. At least one metal braided unit of the support layer is inserted out of the braided structure of the flow-blocking layer along the knitted mesh, and then inserted into the braided structure of the flow-blocking layer along the knitted mesh to form an interlayer connection structure between the support layer and the flow-blocking layer; The metal coverage of the support layer is in the range of 10-40%; the mesh size of the flow-blocking layer is in the range of 20 microns to 200 microns.

2. The knitted stent graft according to claim 1, characterized in that: There are multiple interlayer connection structures, which are evenly distributed along the circumference and axial direction of the knitted coated stent.

3. The knitted stent graft according to claim 1, characterized in that: The support layer includes weaving units arranged along a first weaving direction and weaving units arranged along a second weaving direction. The weaving units in the two weaving directions are interwoven to form a hollow column structure.

4. The knitted stent graft according to claim 1, characterized in that: The flow-blocking layer is knitted using warp knitting or weft knitting.

5. The knitted stent graft according to claim 1, characterized in that: The length of the support layer in the axial direction of the stent is greater than the length of the flow-blocking layer in the axial direction of the stent.

6. The knitted stent graft according to claim 1, characterized in that: The outer diameter of the supporting layer is smaller than the outer diameter of the flow-blocking layer.

7. The knitted stent graft according to claim 1, characterized in that: The number of braided unit wires in the support layer is 2m, 4≤m≤48; The number of braided unit wire heads of the flow-blocking layer is n, where n≥1.

8. The knitted stent graft according to claim 7, characterized in that: The arrangement frequency of the interlayer connection structure in the circumferential direction of the bracket is a, 1≤a≤2m; The arrangement frequency of the interlayer connection structure in the axial direction of the stent is b, b=x*p, p is the braiding layer pitch, and x>0.

9. The knitted stent graft according to claim 1, characterized in that: The cross section of the braided unit includes a special-shaped structure of a circle, a triangle or a hollow ring.

10. The knitted stent graft according to claim 1, characterized in that: The braided unit is made of a material with shape memory properties, or a material containing a radiopaque component, or a mixture of a shape memory material and a radiopaque material.

11. The knitted stent graft according to claim 1, characterized in that: The outer diameter of the stent graft is in the range of 1.5 to 12 mm, and the length is in the range of 10 to 80 mm.

12. The knitted stent graft according to claim 1, characterized in that: When weaving starts or ends, the total number of yarns w involved in weaving is first divided into ƞ weaving yarn groups, the number of yarns in each weaving yarn group is w / ƞ, and ƞ can be 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≤ƞ; the two equally divided bundles rotate in the same direction or opposite directions to form stable yarn bundles, and the two yarn bundles are bound together in parallel to form a closed yarn collection group.

13. The knitted stent graft according to claim 12, characterized in that: The end of the support layer is a partially closed structure, a fully closed structure or a loose structure; The end of the support layer is formed into a partially closed or fully closed structure by winding, splitting and tailing, welding or bonding.

14. The knitted stent graft according to claim 1, characterized in that: The braided units of the support layer and the flow-blocking layer have a single wire diameter or a mixture of multiple wire diameters; The wire diameter of the braiding unit is within the range of 0.0005 inches to 0.005 inches; The wire diameter of the braiding unit of the support layer is greater than or equal to the wire diameter of the braiding unit of the flow-blocking layer.

15. A method for preparing a knitted stent graft, for preparing the stent graft according to any one of claims 1 to 14, characterized in that: The steps include: Using the weaving unit to weave the support layer through a weaving process; The flow-blocking layer is knitted along the outer surface of the support layer by a knitting process, and the knitting units are regularly interspersed in the support layer during the knitting process to obtain the flow-blocking layer and form a knitted stent graft with interlayer connection; The knitted stent graft is subjected to heat treatment to be shaped.

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