Carotid artery micro mesh braid stent

Abstract

The present application relates to the technical field of medical devices, and discloses a carotid artery micro-network braided stent. The present application comprises a stent body divided into a stent middle part and a stent end part, the stent body comprising a first stent, a second stent and a plurality of connecting structures, the first stent and the second stent both being in a hollow tube form and being connected to each other through the connecting structures, the first stent and the second stent being connected at a plurality of positions through the plurality of connecting structures, so as to limit the movement of the first stent and the second stent, and the connecting structures comprising first connecting structures and second connecting structures. The present application realizes the requirements of different slip degrees of the end part and the middle part by setting two different connecting structures on the stent body, realizes the adhesion between the stent layers during use, maintains the integrity of the stent structure, makes the stent closely adhere to the blood vessel, and realizes good support and effective coverage.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical devices, in particular to a carotid artery micro-mesh braided stent. BACKGROUND

[0002] Stroke, also known as apoplexy, has high morbidity, high disability rate, high mortality and other characteristics, and has become the first cause of death in China. Carotid atherosclerotic stenosis is one of the main causes of ischemic stroke. In recent years, for the treatment and improvement of carotid atherosclerotic stenosis, stent implantation has gradually become an effective treatment method to replace carotid endarterectomy due to its high efficiency and minimally invasive characteristics.

[0003] At present, the stents for treating carotid atherosclerosis in the prior art have many problems: 1. The open-loop stent mesh is relatively large and cannot effectively cover the plaque. Its "fish fin effect" affects the internal passing. When the stent is released at the stenosis site of the carotid artery, the stent rod is easy to cut the plaque, causing the plaque to break and fall off. The broken plaque will enter the brain with the blood flow and block the cerebral blood vessels, causing stroke or even death. 2. The mixed braided stent adopts a coarse and fine wire mixed braiding technology, but due to the large difference between the diameters of the coarse and fine wires and other limitations, the processing technology is difficult to realize automatic production. The mixed braided stent produced by manual production has limited capture effect on small size plaque or embolus due to its minimum porosity. When the mixed braided stent is compressed in the sheath, all the wire counts of the stent are in contact with the outer wall of the sheath. During the release and recovery process, the wire and the sheath wall slide, which easily causes the braided structure to be disordered and deformed, affecting the adhesion to the blood vessel after release and the embolus capture performance.

[0004] Although the existing double-layer braided stent can avoid the problems of the mixed braided stent such as non-automatic production and large minimum porosity, the connection strength is weak due to the use of braided connection, so that the radial connection constraint between the layers is limited. When subjected to local extrusion (such as local stenosis plaque extrusion after implantation), the internal micro-mesh deforms and moves inward, and a large gap appears between the layers, affecting blood flow and causing restenosis due to stent thrombosis. Or after implantation, the intimal hyperplasia pushes the inner layer to deform and move inward, forming intimal hyperplasia between the inner and outer layers, causing restenosis. SUMMARY

[0005] In order to solve the above technical problems, the present application provides a carotid artery micro-mesh braided stent, which has different free sliding degrees between the upper layers and the layers at different positions of the stent, and limits the radial sliding degree of the middle part of the stent, to solve the problem of easy separation between the layers of the double-layer stent, and maintain the integrity of the micro-mesh structure, so as to improve the safety and effectiveness of the carotid artery stent.

[0006] The application adopts the following technical scheme: a stent main body is divided into a stent middle part and a stent end part, the stent main body comprises a first stent, a second stent and a plurality of connecting structures, the first stent and the second stent are both in a hollow tube form and are connected to each other through the connecting structures, the first stent and the second stent are connected at a plurality of positions through the plurality of connecting structures, so as to limit the movement of the first stent and the second stent, the connecting structure comprises a first connecting structure and a second connecting structure, the first connecting structure is located in a middle region of the first stent, the second connecting structure is located in a region close to an end part of the first stent, the first stent has a first axial sliding degree and a first radial sliding degree relative to the second stent in the middle region, the first stent has a second axial sliding degree and a second radial sliding degree relative to the second stent in the region close to the end part, the first axial sliding degree is smaller than the second axial sliding degree, and the first radial sliding degree is smaller than the second radial sliding degree, so that the stent end part and the stent middle part are provided with two different connecting structures, the different sliding degree requirements of the stent end part and the stent middle part can be considered, and the adhesion degree and the structural integrity between the stent layers during use can be ensured.

[0007] As a further improvement of the above scheme, the first stent is interlacedly woven by first woven wires, the first stent has a first porosity n1, the first woven wire has a first woven wire cross-sectional area, the second stent is interlacedly woven by second woven wires, the second stent has a second porosity n2 larger than the first porosity, and the second woven wire has a second woven wire cross-sectional area larger than the first woven wire cross-sectional area.

[0008] As a further improvement of the above scheme, the cross-sectional area of the first woven wire is smaller than the cross-sectional area of the second woven wire, and the first porosity n1 is smaller than the second porosity n2, so that the first stent selects a micro-mesh stent with a small porosity and a small wire diameter, and the second stent selects a stent with a large porosity and a large wire diameter, which is beneficial to reduce the contact area between the stent and the pushing outer sheath and reduce the pushing force of the stent main body.

[0009] As a further improvement of the above scheme, the cross-sectional area of the connecting structure is smaller than or equal to the cross-sectional area of the first woven wire, so that the connecting structure can be reduced on the inner and outer surfaces of the stent main body, the surface flatness of the stent main body is improved, and the pushing resistance of the stent main body is reduced.

[0010] As a further improvement of the above scheme, the first stent and the second stent form a close connection at the first connecting structure and form a relative movement connection at the second connecting structure, so as to avoid the separation between the layers of the first stent and the second stent.

[0011] As a further improvement of the above-mentioned solution, the first weaving wire comprises first warp threads and first weft threads, the first warp threads and the first weft threads are two kinds of spiral weaving threads with opposite weaving directions, adjacent first warp threads and first weft threads are cross-woven to form a plurality of first cross points and first mesh holes, the second weaving wire comprises second warp threads and second weft threads, the second warp threads and the second weft threads are two kinds of spiral weaving threads with opposite weaving directions, the second warp threads and the second weft threads are cross-woven to form a plurality of second cross points and second mesh holes, the first stent and the second stent have the same or similar weaving angles.

[0012] As a further improvement of the above-mentioned solution, the first warp threads and the second warp threads have the same direction, the first weft threads and the second weft threads have the same direction, and the second connecting structure connects the first warp threads and the second warp threads.

[0013] And / or, the second connecting structure connects the first weft threads and the second weft threads.

[0014] As a further improvement of the above-mentioned solution, the first connecting structure connects the first cross point and the second cross point which are radially adjacent.

[0015] Or, the first cross point and the second warp thread or the second weft thread which are radially adjacent are connected by the first connecting structure.

[0016] Or, the first warp thread and the second warp thread are connected, and the first weft thread and the second weft thread are connected to form the first connecting structure.

[0017] As a further improvement of the above-mentioned solution, the first connecting structure connects the first cross point and the second cross point which are radially adjacent, and the first connecting structure jointly limits the first warp thread, the first weft thread, the second warp thread, and the second weft thread.

[0018] Or, the first connecting structure connects the first warp thread, the first weft thread, and the second warp thread or the second weft thread, and the first connecting structure jointly limits the first warp thread, the first weft thread, and the second warp thread or the second weft thread, so that the first stent and the second stent can be radially constrained, the separation between the layers can be avoided, the weaving wire has a small degree of sliding in the radial direction, the first weaving wire structure can be adjusted along with the axial change of the pipe diameter, and the weaving structure remains complete and effective.

[0019] As a further improvement of the above-mentioned solution, the first warp thread and the second warp thread are parallel or arranged at an angle within a range of 5°, and the first weft thread and the second weft thread are parallel or arranged at an angle within a range of 5°.

[0020] As a further improvement of the above-mentioned scheme, the first connection structure is distributed in the middle part of the stent body, and is distributed along the second meridian or the second weft. wherein E is the Young's modulus of the first braided wire, d is the wire diameter of the first braided wire, and F is the local extrusion force that the stent may be subjected to after implantation, and F is 0N

[0021] As a further improvement of the above-mentioned scheme, the distance RZ between any two adjacent first connection structures (301) on the stent body satisfies wherein E is the Young's modulus of the first braided wire, d is the wire diameter of the first braided wire, and F is the local extrusion force that the stent may be subjected to after implantation, and F is 0N

[0022] As a further improvement of the above-mentioned scheme, the radius R of the circle determined by any three adjacent first connection structures on the stent body satisfies wherein E is the Young's modulus of the first braided wire, d is the wire diameter of the first braided wire, and F is the local extrusion force that the stent may be subjected to after implantation, and F is 0N

[0023] As a further improvement of the above-mentioned scheme, the second connection structure is spaced apart from the stent end by at least one first intersection point, and the second connection structure is distributed in the stent end and distributed along the second meridian or the second weft.

[0024] Alternatively, the second connection structure is distributed along the second meridian or the second weft, the second connection structure farthest from the stent body has an axial distance X from the first stent end of not more than 2 mm, and the radial projection angle formed by two adjacent second connection structures and the center of the stent cross section is less than or equal to 120°.

[0025] As a further improvement of the above-mentioned scheme, the first connection structure is distributed in the middle part of the stent, and the second connection structure is distributed in the end part of the stent and distributed along the second meridian or the second weft, and at least one second connection structure is provided near the first connection structure farthest from the stent body, so that the connection structure has a radial constraint range for the first stent and the second stent, and within this range, the bending moment of the braided wire under stress is limited, which can effectively avoid interlayer separation in a local range.

[0026] As a further improvement of the above-mentioned scheme, the connection structure further comprises a third connection structure, and the first stent and the second stent are tightly connected at the third connection structure; the third connection structure is located in the middle region of the first stent and is mixedly arranged with the first connection structure.

[0027] Alternatively, the third connecting structure is located between the first connecting structure and the second connecting structure region.

[0028] As a further improvement of the above-mentioned scheme, a buffer hopper in the form of a funnel as a whole is arranged in the cavity of the first stent, the buffer hopper is divided into three parts of an expanding end, a body and a tightening end, the buffer hopper is interlaced woven by a plurality of third interlaced woven wires, the expanding end of the buffer hopper is connected with the first interlaced woven wire on the first stent, and the buffer hopper can buffer blood flow to avoid excessive perfusion.

[0029] As a further improvement of the above-mentioned scheme, the tightening end of the buffer hopper is provided with a plurality of expanding seams distributed in the form of a ring, so that after the patient adapts to the increase in blood flow, the buffer hopper gradually reduces the obstruction to blood flow, thereby ensuring blood supply.

[0030] Compared with the prior art, the present application has the following advantages:

[0031] The first stent is a thin stent, and the second stent is a thick stent, the second stent provides main support force for the stent body, so that the stent body can be closely attached to the blood vessel to achieve effective support and good coverage; due to the micro-mesh structure of the first stent, after being released in the blood vessel, the first stent can better cover the plaque, prevent the prolapse or rupture of the plaque, and avoid the entry of the plaque into the downstream of the blood vessel to cause stroke, etc.

[0032] The close constraint provided by the first connecting structure is a strong connection, which can effectively ensure the adhesion of the working area of the stent body, avoid the delamination of the stent body before and after use, especially when the stent body is locally extruded, improve the adhesion effectiveness of the stent body, reduce the risk of thrombosis and hyperplasia in the stent, and improve the use safety of the stent.

[0033] The gap constraint provided by the second connecting structure can give the stent body a greater axial and radial sliding degree in the end region close to the end than in the middle region, thereby avoiding the deformation or damage of the stent body caused by the inevitable relative movement of the stent body, and ensuring the good support and effective coverage of the stent on the plaque.

[0034] By adopting the first connecting structure in the middle of the stent and the second connecting structure in the end region close to the end, the stent body can adaptively adjust the woven structure to a certain extent by the sliding of the wires under different diameters of the blood vessel, so that the stent can better cover the plaque, prevent the prolapse or rupture of the plaque, avoid the entry of the plaque into the downstream of the blood vessel to cause stroke, and avoid the problem of interlayer separation of the stent during use, thereby maintaining the smoothness and integrity of the micro-mesh stent structure during compression and expansion, reducing the risk of restenosis in the stent, and improving the use safety of the stent body.

[0035] After carotid artery stent surgery, the blood flow of the diseased blood vessel will suddenly increase after being supported by the stent, which may cause excessive perfusion, causing symptoms such as headache and dizziness. By setting a buffer hopper inside the stent, the buffer hopper can buffer the blood flow to some extent, thereby reducing the blood pressure. And because the tightening end of the buffer hopper is provided with an expansion seam, which makes the buffer hopper gradually reduce the effect of hindering blood, so as to buffer an adaptation period, thereby solving the problem of excessive perfusion that may occur after stent surgery. And the structure of the buffer hopper is similar to the first stent and the second stent, which also has expansion, so it can also assist the first stent and the second stent to support the blood vessel and avoid restenosis. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 It is the first schematic diagram of the carotid artery micro-mesh braided stent of the application;

[0037] Figure 2 It is the second schematic diagram of the carotid artery micro-mesh braided stent of the application;

[0038] Figure 3 It is the compression braiding angle variable diagram of the carotid artery micro-mesh braided stent of the application;

[0039] Figure 4 It is a display diagram of the second connecting structure and a connecting method cross-sectional diagram;

[0040] Figure 5 It is a display diagram of the first connecting structure and two connecting method cross-sectional diagrams thereof;

[0041] Figure 6 It is a display diagram of the second embodiment of the first connecting structure and a cross-sectional diagram of the connecting method thereof, in which the first intersection and the radially adjacent second weft are connected by the first connecting structure;

[0042] Figure 7 It is a display diagram of the third embodiment of the first connecting structure and a cross-sectional diagram of the connecting method thereof, in which the first weft and the second weft are connected;

[0043] Figure 8 It is a point distribution diagram of the first connecting structure;

[0044] Figure 9 It is an unfolding diagram of the carotid artery micro-mesh braided stent of the application;

[0045] Figure 10 It is a point distribution diagram of the second connecting structure;

[0046] Figure 11 It is a point distribution diagram of the first connecting structure and the second connecting structure;

[0047] Figure 12A planar display view of the carotid artery micro-mesh braided stent and buffer hopper;

[0048] Figure 13 A three-dimensional sectional display view of the carotid artery micro-mesh braided stent and buffer hopper;

[0049] Figure 14 A planar display view of the buffer hopper.

[0050] Main symbol explanation:

[0051] 1, first stent; 2, second stent; 3, connecting structure; 301, first connecting structure; 302, second connecting structure; 4, first braided wire; 401, first warp; 402, first weft; 5, second braided wire; 501, second warp; 502, second weft; 6, flared portion wire; 7, buffer hopper; 8, expansion slit. DETAILED DESCRIPTION

[0052] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should fall within the scope of protection of the present application.

[0053] In the present application, the terms "proximal end" and "distal end" are the relative orientation, relative position, direction of elements or actions relative to each other from the perspective of the operator using the medical device, although "proximal end" and "distal end" are not restrictive, but "proximal end" generally refers to the end of the medical device close to the operator during normal operation, and "distal end" generally refers to the end first entering the patient's body.

[0054] Those skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to suggest that the scope (including claims) of the present application is limited to these examples; under the idea of the present application, the above embodiments or technical features between different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the present application as described above. In order to be brief, they are not provided in detail.

[0055] The present application will be further described below in conjunction with the drawings and specific embodiments.

[0056] Please combine Figures 1 to 14 , the carotid artery micro-mesh braided stent, comprising: a stent body divided into a stent middle part and a stent end part, the stent body comprising a first stent 1, a second stent 2 and a plurality of connecting structures 3;

[0057] The first stent 1 is formed by interlacing the first braided wires 4 to form a hollow general tube shape, the first stent 1 has a first porosity, the first braided wires 4 have a first braided wire 4 cross-sectional area, the proximal outer diameter of the first stent 1 is greater than or equal to the distal outer diameter, the proximal outer diameter of the second stent 2 is greater than or equal to the distal outer diameter, that is, the stent body can be cylindrical or conical;

[0058] The second stent 2 is formed by interlacing the second braided wires 5 to form a hollow general tube shape, the second stent 2 has a second porosity different from the first porosity, the second braided wires 5 have a second braided wire 5 cross-sectional area different from the first braided wire 4 cross-sectional area, the second stent 2 has flared portions at both ends, the flared portions are provided with flared lines 6, the flared lines 6 are connected two by two to form closed ends. The flared lines can also be open or connected in a closed loop.

[0059] The first braided wires 4 include first warp threads 401 and first weft threads 402, the first warp threads 401 and the first weft threads 402 are two kinds of spiral braided threads with opposite braiding directions (i.e. clockwise or counterclockwise), adjacent first warp threads 401 and first weft threads 402 are interlaced to form a plurality of first intersection points and first mesh holes, the second braided wires 5 include second warp threads 501 and second weft threads 502, the second warp threads 501 and the second weft threads 502 are two kinds of spiral braided threads with opposite braiding directions (i.e. clockwise or counterclockwise), the second warp threads 501 and the second weft threads 502 are interlaced to form a plurality of second intersection points and second mesh holes.

[0060] When the flared portion of the second stent 2 is a closed loop, the second warp threads 501 and the second weft threads 502 at the ends of the second stent 2 are connected two by two to form closed ends.

[0061] The first stent 1 and the second stent 2 have the same or similar braiding angles, the materials of the first stent 1 and the second stent 2 are medical metal wires, the medical metal materials include medical stainless steel, nickel-titanium memory alloy, cobalt-based alloy, titanium alloy, magnesium alloy, etc., preferably nickel-titanium memory alloy, at least one of the braided wires of the first stent 1 or the second stent 2 has radiopacity;

[0062] The first stent 1 and the second stent 2 are connected at multiple positions by the connecting structure 3, so as to limit the relative movement of the first stent 1 and the second stent 2; the connecting structure 3 comprises a first connecting structure 301 and a second connecting structure 302, the first connecting structure 301 is located in the middle region of the first stent 1, the middle region of the first stent 1 is located in the middle part of the stent, the second connecting structure 302 is located in the end region close to the end of the first stent 1, the end region close to the end of the first stent 1 is located in the end part of the stent, the first stent 1 has a first axial sliding degree and a first radial sliding degree in the middle region relative to the second stent 2, the first stent 1 has a second axial sliding degree and a second radial sliding degree in the end region close to the end relative to the second stent 2, the first axial sliding degree is smaller than the second axial sliding degree, and the first radial sliding degree is smaller than the second radial sliding degree, so that two different connecting structures 3 are arranged at the end part and the middle part of the stent, the different sliding degree requirements of the end part and the middle part of the stent are considered, the adhesion degree and the structural integrity between the layers of the vascular stent are ensured during use, and good support and effective coverage of the carotid artery micro-mesh braided stent are realized.

[0063] Through the above technical solution, the middle part of the stent is the main working area of the stent body, the first stent 1 mainly provides effective coverage for the lesion plaque, prevents the movement, prolapse or shedding of the plaque, the second stent 2 provides sufficient support force, and the two stents jointly act. Combined with the treatment mechanism of the vascular stent, the stenosis lesion is mechanically expanded, and the blood vessel is reconstructed by subsequent re-endothelialization coverage. The small relative movement or no relative movement between the stents is beneficial to the adhesion effect of the stent and beneficial to the endothelial growth and completion of the blood vessel reconstruction.

[0064] Further, in the embodiment, the first stent 1 is located in the cavity of the second stent 2, the cross-sectional area or wire diameter of the first braided wire 4 is different from the cross-sectional area or wire diameter of the second braided wire 5, the first stent 1 on the stent body is located in the inner cavity of the second stent 2, the outer diameters of the two stents are different, and the outer diameter of the first stent 1 is greater than the inner diameter of the second stent 2.

[0065] Although the first stent 1 and the second stent 2 have the same or similar weaving angles in the expanded state, the change amounts of the weaving angles of the two stents are different in the compression process, so that the weaving angle of the first stent cannot be kept the same or similar to that of the second stent in the compression process, which is manifested as that the first stent 1 and the second stent 2 have relatively large relative movement in the axial direction. Considering the processing technology limitation of the stent and the precision limit, the above process causes the first stent 1 and the second stent 2 to have axial relative movement in the expansion or contraction process. If the two stents are forced to be constrained so as to have no relative movement in the axial direction, the integrity of the stent body will be affected, or the stent body will be deformed or damaged, which affects the safety and effectiveness of the use of the stent body. If no certain constraint is given so as to have relatively large relative movement in the radial direction, the stent body will be separated by displacement, which affects the support coverage performance of the stent body. The first connecting structure 301 and the second connecting structure 302 are arranged in the middle part and the end part of the stent respectively to give different axial slip degrees, which reduces the possibility of unavoidable relative movement, deformation or displacement separation of the stent body caused by the geometric structure and processing of the stent body, thereby improving the wall-adhesion effect of the stent body, reducing the restenosis probability of the stent, and reconstructing the blood vessel. At the same time, the first connecting structure 301 causes the first stent 1 and the second stent 2 to have small relative movement or no relative movement in the radial direction, which is beneficial to the wall-adhesion effect of the stent body, is beneficial to the completion of endothelial growth, and reduces the restenosis in the stent body, so as to reconstruct the blood vessel.

[0066] At the end part of the stent, in addition to having certain relative movement in the axial direction, the first stent 1 and the second stent 2 have different expansion forces in the end part in the expansion or contraction process (including local extrusion) due to the differences in the material, the cross-sectional area of the weaving wire and the weaving structure of the first stent 1 and the second stent 2, which is manifested as that the end part of the first stent 1 and the second stent 2 has relative movement in the radial and axial directions, and the greater the difference in the cross-sectional area or the wire diameter of the weaving wire of the first stent 1 and the second stent 2 and the greater the difference in the weaving porosity, the more obvious the relative movement.

[0067] In the expansion or contraction process of the stent body, a single weaving wire has only the proximal end constrained, and the distal end of the stent body has no external force constraint, which can be regarded as a "cantilever beam unit". At this time, the internal force of the distal end of the "cantilever beam" is mainly the anti-deformation force of the weaving wire itself, which is related to the cross-sectional area, material and geometric structure of the weaving wire. Under the influence of the weaving of adjacent weaving wires, the adjacent weaving wires constrain the expansion of the "cantilever beam" and provide a compression force inward. The anti-deformation force of the weaving wire and the compression force of the adjacent weaving wire jointly determine the final shape of the weaving wire. The more the number of weaving wires is distributed, the more obvious the compression force influence is, the more the weaving wire is retracted, and the smaller the expansion degree of the end part of the stent is.

[0068] The sliding amount of the stent braided wire (the first braided wire 4 and the second braided wire 5) accumulates and superimposes from the middle to the two ends in the process of expansion or contraction without other constraints; if the stent is in the sheath, the stent braided wire sliding amount accumulates from the proximal end, and reaches the maximum at the distal end; considering the stent processing technology limit and precision limit, the above process makes the first stent 1 and the second stent 2 necessarily exist axial relative movement in the process of expansion / contraction, and if the two stents are forced to be constrained without relative movement, the stent integrity will be affected, or the stent will be deformed or damaged, affecting the safety and effectiveness of the stent.

[0069] In view of the above reasons, by giving different axial sliding degrees between the upper and lower layers of the stent at different positions, and limiting the radial sliding degree of the middle part of the stent, the interlayer separation problem of the double-layer stent in the background technology is solved, and the structure of the stent is prevented from being deformed and damaged, so as to further improve the safety and effectiveness of the carotid stent.

[0070] In this embodiment, the first braided wire 4 of the first stent 1 and the second braided wire 5 of the second stent 2 are not interwoven, that is, the first braided wire 4 of the first stent 1 and the second braided wire 5 of the second stent 2 are not interwoven.

[0071] Please refer to Figures 4 to 7 , the first connecting structure 301 includes a first loop for connecting the first stent 1 and the second stent 2, and the first loop is perpendicular to the axis of the stent body (carotid artery micro-mesh braided stent); the second connecting structure 302 includes a second loop for connecting the first stent 1 and the second stent 2, and the second loop is perpendicular to the extension direction of the braided wire connected by the second connecting structure 302.

[0072] The first loop is perpendicular to the axis of the stent body (carotid artery micro-mesh braided stent), that is, the winding direction of the first loop is along the radial direction of the stent. The second loop is perpendicular to the extension direction of the braided wire connected by the second connecting structure 302, that is, the winding direction of the second loop is along the radial direction of the braided wire.

[0073] The connecting structure 3 is provided as a wire winding structure, and the connecting interface formed after winding of the connecting structure 3 is placed between the stent braided meshes to avoid causing abnormal protrusions on the outer surface of the stent and increasing the pushing resistance of the stent;

[0074] Specifically, one or more wires are wound around a fixed point for a certain number of turns (the wound wire turns are arranged in parallel), and the interface is fixed by knotting, heat melting or adhesion (knotting fixation, such as square knot, surgical knot, etc., the wire port after knotting is expanded or fixed to avoid knot sliding and loosening, and the knot holding effectiveness is improved); the interface maintains its firmness under micro-vibration;

[0075] The material of the connecting structure 3 is a metal material or a polymer material, preferably a polymer material. The polymer material of the connecting structure 3 is preferably a flexible wire made of a biocompatible polymer material such as polytetrafluoroethylene (PTFE), polyethylene terephthalate (PET), polypropylene (PP), polylactic acid (PLA), polydioxanone (PDO), etc. The connecting wire can be single-stranded or multi-stranded. Preferably, a single-stranded wire is smoother and less likely to hide the source of infection.

[0076] Specifically, the cross-sectional area or wire diameter of the first braided wire 4 is smaller than that of the second braided wire 5, and the first porosity n1 is smaller than the second porosity n2. In this way, the first stent 1 arranged in the inner layer is a micro-mesh stent with small porosity and small wire diameter, and the second stent 2 arranged in the outer layer is a stent with large porosity and large wire diameter, which is beneficial to reduce the contact area between the stent and the push sheath and reduce the pushing resistance of the stent. In addition, the micro-mesh of the first stent 1 is in the inner layer, which can avoid direct contact with the plaque and continuous cutting of the plaque into small size plaques, and when the plaque prolapses through the outer layer mesh, the inner layer micro-mesh still provides protection.

[0077] Further, n2=c*n1, and the range of c is 1

[0078] The cross-sectional area of the connecting structure 3 is less than or equal to the cross-sectional area of the first braided wire 4. Selecting a small cross-sectional area of the connecting structure 3 is beneficial to reduce the protrusion of the connecting structure 3 on the inner and outer surfaces of the stent body, improve the surface flatness of the stent body, and reduce the pushing resistance of the stent body.

[0079] At the first connecting structure 301, the first stent 1 and the second stent 2 are tightly connected through the first connecting structure 301.

[0080] At the second connecting structure 302, the second connecting structure 302 has a gap with the first stent 1 and the second stent 2 at some positions, i.e., the first stent 1 and the second stent 2 are relatively movable connected through the second connecting structure 302.

[0081] The middle part of the stent is the main working area of the stent body, so the relative movement between the first stent 1 and the second stent 2 in the radial direction of this area is as small as possible; at the same time, the middle part of the stent body has different outer diameters of the two stents, although the braiding angle of the stent in the expanded state is consistent, the change amount of the braiding angle of the two stents in the compression process is different, which is that the first stent 1 and the second stent 2 have a certain relative movement in the axial direction. In addition, considering the processing technology limitation and precision limit of the stent, the first stent 1 and the second stent 2 must have axial relative movement during the expansion / contraction process of the double-layer stent. If the relative movement of the two stents is forcibly constrained, the integrity of the stent will be affected, or the stent will be deformed or damaged, which will affect the safety and effectiveness of the stent. The middle part of the stent of the present application is tightly connected by the first connecting structure 301, which avoids the separation of the first stent 1 and the second stent 2 in this area, is beneficial to the wall-adhesion effect of the stent, is beneficial to the completion of endothelial growth and vascular reconstruction; at the same time, the first stent 1 and the second stent 2 are given a small possibility of axial movement, which avoids the deformation and damage of the stent.

[0082] The end part of the stent, in addition to the certain relative movement of the first stent 1 and the second stent 2 in the axial direction, due to the differences in material, cross-sectional area of braiding wire and braiding structure of the two stents, the expansion force of the two stents at the end part is different during the expansion or compression process (including local extrusion), which is that the end part of the two stents has relative movement in the radial and axial directions. And the relative movement is more obvious with the greater difference in cross-sectional area of braiding wire and the greater difference in braiding porosity. The second connecting structure 302 is used for relative movement connection of the stent near the end part, which gives the first stent 1 and the second stent 2 a larger possibility of axial movement and radial movement relative to the middle part, and avoids the deformation or damage of the stent caused by the inevitable relative movement of the stent.

[0083] In summary, by giving different slip degrees between the upper layer and the lower layer at different positions of the stent, providing small axial displacement and strong radial constraint in the middle part, leaving larger axial displacement and relatively smaller radial constraint at the two ends, the problem of separation between the layers of the double-layer stent in the background technology is solved, and the deformation and damage of the stent structure are avoided, so as to further improve the safety and effectiveness of the carotid stent.

[0084] Please refer to Figure 3, the first stent 1 and the second stent 2 have the same or similar weaving angles, the first warp 401 is arranged in parallel with the second warp 501 or at an angle within a range of 5°, and the first weft 402 is arranged in parallel with the second weft 502 or at an angle within a range of 5°, so that the two have close expansion and contraction rates, the relative movement between the two is reduced when the vascular stent is contracted and expanded, and the layers are fitted together during use; in this way, the first stent 1 and the second stent 2 have substantially similar geometric structures (which can be overall similar or similar at the same relative positions of the two stents), and the first stent 1 and the second stent 2 are connected by the proximal ends and the distal ends.

[0085] As Figure 3 , taking the woven wire M and the woven wire N as the first woven wire 4 of the first stent 1 and the woven wire P and the woven wire Q as the second woven wire 5 of the second stent 2 as an example, in the initial state, the first stent 1 and the second stent 2 have the same or similar weaving angles in the expanded state, the woven wire M is parallel to the woven wire P or within a certain range of angles, and the woven wire N is parallel to the woven wire Q or within a certain range of angles, at which time the point m1 on the woven wire M, the point n1 on the woven wire N, the point p1 on the woven wire P, and the point q1 on the woven wire Q are in overlapping positions. During the compression of the stent body into the delivery system, the weaving angles of the first stent 1 and the second stent 2 change differently during the compression process, and if the point m1, n1, p1, and q1 are not connected by a fixed connection structure, the point m1, n1, p1, and q1 will present the problem of unlimited movement and displacement separation between the first stent 1 and the second stent 2; if the point m1, n1, p1, and q1 are fixed by a fixed connection structure, the first stent 1 or the second stent 2 will be deformed. Similarly, when the stent body is released from the delivery system and expanded to the deployment position, the relative movement between the first stent 1 and the second stent 2 cannot be avoided, which leads to the displacement separation or deformation of the stent. The first connection structure 301 provided in the middle part of the stent in the stent body of the present application is closely connected with the first stent 1 and the second stent 2, which provides a certain degree of sliding in the axial direction of the first stent 1 and the second stent 2, reduces the sliding degree of the first stent 1 and the second stent 2 in the radial direction, controls the different sliding degrees of the stent in the axial and radial directions, and meets the clinical needs of stent structure self-adaptive adjustment and prevention of interlayer separation, thereby effectively reducing the risk of plaque prolapse and in-stent restenosis.

[0086] Please refer to Figure 8 and Figure 9 , the first connection structure 301 is distributed in the middle part of the stent body along the second warp 501 or the second weft 502; the distance RZ between any two adjacent first connection structures 301 on the side surface of the stent body satisfies , wherein E is the Young's modulus of the first braided wire, d is the diameter of the first braided wire, and F is the local extrusion force that the stent can be subjected to after implantation, and F satisfies 0N < F≤ 1N. That is, in the distance range Rz of any first connecting structure 301, there is at least one first connecting structure 301, wherein In this way, the connecting structure 3 is not too sparse, and the layer-to-layer adhesion effectiveness between the first stent 1 and the second stent 2 is not limited. The reasonable distribution of the connecting structure 3 has a significant impact on the safety and effectiveness of the first stent 1 and the second stent 2. The first connecting structure 301 has a certain radial constraint range on the stent body. Within this range, the bending moment of the braided wire is limited, and local layer separation can be effectively avoided. This radial constraint range is mainly affected by the diameter and material properties of the first braided wire 4.

[0087] Further, on the side unfolding structure of the stent body, the distance between any two adjacent first connecting structures 301 satisfies , wherein E is the Young's modulus of the first braided wire, d is the diameter of the first braided wire, and F is the local extrusion force that the stent can be subjected to after implantation, and F satisfies 0N < F≤ 1N. In this way, the connecting structure between the first stent 1 and the second stent 2 is not too dense, and the shear force of the braided wire is not significantly increased during use, which affects the fatigue durability of the implanted stent. Moreover, too many connection points are introduced, which increases the pushing resistance of the stent and increases the product cost.

[0088] Further, on the stent body, the radius R of the circle determined by any three adjacent first connecting structures satisfies , wherein E is the Young's modulus of the first braided wire, d is the diameter of the first braided wire, and F is the local extrusion force that the stent can be subjected to after implantation, and F satisfies 0N < F≤ 1N. In this way, the connecting structure on the stent body is evenly distributed, and the layer-to-layer adhesion effectiveness between the first stent 1 and the second stent 2 is not limited.

[0089] Please refer to Figure 10, the second connection structure 302 is distributed on the second warp 501 or the second weft 502, and the second connection structure 302 farthest from the stent body has an axial distance X of not more than 2mm from the first stent 1 end, and the radial projection angle formed by the two adjacent second connection structures 302 and the stent cross center is not more than 120°; that is, any second connection structure 302 has at least one first connection structure 301 or second connection structure 302 within its distance RZ range; in this way, the second connection structure 302 has a certain radial constraint range on the stent, and the bending moment of the woven wire under stress is limited, which can effectively avoid local range interlayer separation (such as fish mouth phenomenon). The radial constraint range is mainly affected by the wire diameter and material properties of the first woven wire 4. The "fish mouth phenomenon" often occurs at locations with large diameter span, especially for stents woven by wires with small cross-sectional area, such as flow diverters FD. Carotid stents are often used for carotid bifurcation and internal carotid artery, and the stent often covers the internal carotid artery and the common carotid artery, with large diameter difference. The first stent 1 has a small woven wire cross-sectional area due to the micro-mesh structure, and when the blood vessel size and the stent size are not suitable, the above-mentioned "fish mouth phenomenon" may occur, affecting the stent wall adhesion effect and blood flow dynamics, and increasing the probability of restenosis. The connection structure 3 arranged at the end can avoid the "fish mouth phenomenon". Because the two stent ends have different expansion forces, and the expansion force gradually increases away from the stent body, the middle and end regions are reserved for movement of the excess region for fixing the two stents to the movable excess, avoiding excessive constraint. Or because the two stent ends have different expansion forces, and the expansion force gradually increases away from the stent body, the axial displacement of the end wire is required, and the woven wire needs to have axial freedom within a certain range around the second connection structure 302.

[0090] Please refer to Figure 11 , the first connection structure 301 is distributed in the middle of the stent, the second connection structure 302 is distributed at the end of the stent and along the second warp 501 or the second weft 502, and the first connection structure 301 farthest from the stent body has at least one second connection structure 302 within its distance RZ range; in this way, the connection structure 3 has a certain radial constraint range on the first stent 1 and the second stent 2, and the bending moment of the woven wire under stress is limited, which can effectively avoid local range interlayer separation.

[0091] Please refer to Figure 1 and Figure 4 , the weaving direction of the first warp 401 and the second warp 501 is the same, and the weaving direction of the first weft 402 and the second weft 502 is the same; see Figure 1The second connecting structure 302 connects the first warp 401 and the second warp 501; and / or, the second connecting structure 302 connects the first weft 402 and the second weft 502. In this way, the second connecting structure 302 selects two wires in the same direction to be connected, only one braided wire of each support is radially constrained, and a larger moving space is provided in the axial direction, which can ensure that the two supports have axial constraint fit before and after use, and the braided wire has relative movement in the radial direction, avoiding connection failure or braided structure deformation and damage, so that the support has better safety and effectiveness.

[0092] Please refer to Figure 1 、 Figures 5 to 7 In the first embodiment of the present application, the first connecting structure 301 connects the radially adjacent first intersection and second intersection, as shown in Figure 1 The connecting structure of the middle A region;

[0093] Specifically, the radially adjacent first intersection and second intersection are connected by the first connecting structure 301, and the first connecting structure 301 limits the first warp 401, the first weft 402, the second warp 501 and the second weft 502 together;

[0094] Alternatively, the first connecting structure 301 connects the first warp 401, the first weft 402, the second warp 501 or the second weft 502, and the first connecting structure 301 limits the first warp 401, the first weft 402, the second warp 501 or the second weft 502 together. In this way, the first support 1 and the second support 2 can be radially constrained to avoid separation between the layers, and the braided wire has a small degree of sliding in the radial direction, so that the first braided wire 4 structure can be adjusted with the axial change of the pipe diameter in different states such as expansion or contraction, and the braided structure remains complete and effective.

[0095] The first connecting structure 301 tightly constrains the first support 1 and the second support 2 in the radial direction, and the two warps and the two wefts at the intersection are closely adjacent with no gap therebetween through the connection of the first connecting structure 301;

[0096] The first loop of the first connecting structure 301 is perpendicular to the support axis; the second connecting structure 302 connects one first warp 401 (or first weft 402) of the first support 1 and one second warp 501 (or second weft 502) of the second support 2;

[0097] The second loop of the second connecting structure 302 is perpendicular to the connected support warp (or weft), and the second connecting structure 302 has a gap between the first braided wire 4 or the second braided wire 5, thereby providing a certain degree of sliding of the connected warp (or weft) in the axial direction.

[0098] In the second embodiment of the present application, the first intersection point is connected with the radially adjacent second meridian 501 or second parallel 502 through the first connection structure 301, as shown in Figure 1 Connection structure in the middle B region.

[0099] In the third embodiment of the present application, the first meridian 401 is connected with the second meridian 501, and the first parallel 402 is connected with the second parallel 502 to form the first connection structure 301, as shown in Figure 1 Connection structure in the middle C region.

[0100] The connection scheme of the above first connection structure 301 can provide radial strong connection, limit the radial relative displacement of the two stents, and give the two stents a certain degree of axial slip; make the two stent layers have no gap and maintain the structural integrity.

[0101] In the fourth embodiment of the present application, the connection structure 3 further comprises a third connection structure, which is located in the middle region of the first stent 1 and is mixedly arranged with the first connection structure 301, and the first stent 1 and the second stent 2 form a tight connection at the third connection structure; or is arranged between the first connection structure 301 and the second connection structure 302 region in the axial direction of the first stent 1. The third connection structure is arranged at the position where the first connection structure 301 cannot be arranged on the stent, which provides further radial slip degree limit for the stent, thereby ensuring that the stent exists in the connection structure within any RZ range, to avoid the separation of the stent layers and reduce the risk of in-stent restenosis.

[0102] For the connection arrangement of the third connection structure with the braided wires of the first stent 1 and the second stent 2, the third connection structure connects the first intersection point and the adjacent second meridian 501 or second parallel 502; or the third connection structure connects the adjacent first meridian 401, first parallel 402 and second meridian 501 or second parallel 502, and the third connection structure jointly limits the first meridian 401, first parallel 402 and second meridian 501 or second parallel 502.

[0103] The positional arrangement relationship of the third connection structure with the first connection structure and the second connection structure on the stent is the same as the positional arrangement relationship between the first connection structure and the second connection structure on the stent, which will not be repeated here.

[0104] Please refer to Figures 12 to 14, The cavity of the first stent 1 is further provided with a buffer hopper 7 in the form of a whole funnel, the buffer hopper 7 is divided into three parts of an expansion end, a body and a tightening end, the buffer hopper 7 is interlaced woven by a plurality of third interlaced wires, and the density is higher than that of the first stent 1, the expansion end of the buffer hopper 7 is connected with the first interlaced wire 4 on the first stent 1, the blood flow can be buffered through the buffer hopper 7, and excessive perfusion can be avoided, the tightening end of the buffer hopper 7 is provided with a plurality of expansion seams 8 distributed in the form of a ring, so that the buffer hopper 7 gradually reduces the obstruction to the blood flow after the patient adapts to the increase of the blood flow, thereby ensuring blood supply.

[0105] After the carotid stent surgery, the blood flow of the original diseased blood vessel will suddenly increase after being supported by the stent, which may cause excessive perfusion, causing symptoms such as headache and dizziness, and even cerebral hemorrhage may occur, therefore, the buffer hopper 7 can limit the blood pressure to a certain extent, and the buffer hopper 7 is provided with expansion seams 8, so that the tightening end of the buffer hopper 7 gradually expands with the continuous impact of the blood flow, and during this period, it is the adaptation period of the patient, so that the patient can gradually adapt to the increase of the blood pressure, and after adaptation, the obstruction to the blood flow is minimized.

[0106] The above-mentioned embodiments are only preferred embodiments of the present application, and cannot be used to limit the scope of protection of the present application, and any non-essential changes and replacements made by those skilled in the art on the basis of the present application all belong to the scope of protection required by the present application.

Claims

1. A carotid micro mesh braided stent, characterized in that, The application relates to a stent body divided into a stent middle part and a stent end part, the stent body comprising a first stent (1), a second stent (2) and a plurality of connecting structures (3), the first stent (1) and the second stent (2) are both hollow tubes and are connected to each other through the connecting structures (3), and the stent body is characterized in that: The first stent (1) and the second stent (2) are connected at multiple positions through the connecting structures (3), so that the movement of the first stent (1) and the second stent (2) can be limited, the connecting structures comprise first connecting structures (301) and second connecting structures (302), the first connecting structures (301) are located in the middle region of the first stent (1), the second connecting structures (302) are located in the region close to the end part of the first stent (1), the first stent (1) has a first axial sliding degree and a first radial sliding degree relative to the second stent (2) in the middle region, the first stent (1) has a second axial sliding degree and a second radial sliding degree relative to the second stent (2) in the region close to the end part, the first axial sliding degree is smaller than the second axial sliding degree, and the first radial sliding degree is smaller than the second radial sliding degree. The first stent (1) is formed by interlaced weaving of first weaving wires (4), the first stent (1) has a first porosity n1, the first weaving wires (4) have a first weaving wire (4) cross-sectional area, the second stent (2) is formed by interlaced weaving of second weaving wires (5), the second stent (2) has a second porosity n2 which is larger than the first porosity, and the second weaving wires (5) have a second weaving wire (5) cross-sectional area which is larger than the first weaving wire (4) cross-sectional area.

2. The carotid micro mesh braid stent of claim 1, wherein, The cross-sectional area of the connecting structure (3) is equal to or smaller than the cross-sectional area of the first weaving wire (4).

3. The carotid micro mesh braid stent of claim 2, wherein, The first stent (1) and the second stent (2) form a close connection at the first connecting structure (301) and a relative movement connection at the second connecting structure (302).

4. The carotid micro mesh braid stent of claim 2, wherein, The first weaving wires (4) comprise first warp wires (401) and first weft wires (402), the first warp wires (401) and the first weft wires (402) are two kinds of spiral weaving wires with opposite weaving directions, adjacent first warp wires (401) and first weft wires (402) are interlaced to form a plurality of first intersection points and first mesh holes, the second weaving wires (5) comprise second warp wires (501) and second weft wires (502), the second warp wires (501) and the second weft wires (502) are two kinds of spiral weaving wires with opposite weaving directions, the second warp wires (501) and the second weft wires (502) are interlaced to form a plurality of second intersection points and second mesh holes, and the first stent (1) and the second stent (2) have the same or similar weaving angles.

5. The carotid micro mesh braid stent of claim 4, wherein, The first warp wires (401) and the second warp wires (501) are in the same direction, the first weft wires (402) and the second weft wires (502) are in the same direction, and the second connecting structure (302) connects the first warp wires (401) and the second warp wires (501).

6. The carotid micro mesh braid stent of claim 5, wherein, ​ And / or, the second connecting structure (302) connects the first weft (402) and the second weft (502).

7. The carotid micro mesh braid stent of claim 5, wherein, The first connecting structure (301) connects the radially adjacent first intersection and the second intersection; Or, the first intersection is connected with the radially adjacent second warp (501) or second weft (502) through the first connecting structure (301); Or, the first warp (401) and the second warp (501) are connected, and the first weft (402) and the second weft (502) are connected to form the first connecting structure (301).

8. The carotid micro mesh braid stent of claim 7, wherein, The radially adjacent first intersection and the second intersection are connected through the first connecting structure (301), and the first connecting structure (301) commonly limits the first warp (401), the first weft (402), the second warp (501), and the second weft (502); Or, the first connecting structure (301) connects the first warp (401), the first weft (402), and the second warp (501) or the second weft (502), and the first connecting structure (301) commonly limits the first warp (401), the first weft (402), and the second warp (501) or the second weft (502).

9. The carotid micro mesh braid stent of claim 5, wherein, The first warp (401) and the second warp (501) are parallel or arranged at an angle within a range of 5°, and the first weft (402) and the second weft (502) are parallel or arranged at an angle within a range of 5°.

10. The carotid micro mesh braid stent of claim 5, wherein, The first connecting structure (301) is distributed in the stent middle part of the stent body, and is distributed along the second meridian line (501) or the second parallel line (502). The distance RZ between any two adjacent first connecting structures (301) on the stent body satisfies Wherein, E is the Young's modulus of the first braided wire, d is the wire diameter of the first braided wire, and F is the local extrusion force that the stent may be subjected to after implantation, and F takes a value of 0N<F≤1N.

11. The carotid micro mesh braid stent of claim 10, wherein, On the stent body, the distance RZ between any two adjacent first connection structures (301) satisfies Wherein E is the Young's modulus of the first braided wire, d is the wire diameter of the first braided wire, and F is the local extrusion force that the stent can be subjected to after implantation, and F takes a value of 0N<F≤1N.

12. The carotid micro mesh braid stent of claim 10, wherein, On the stent body, the radius R of a circle determined by any three adjacent first connection structures satisfies wherein E is the Young's modulus of the first braided wire, d is the wire diameter of the first braided wire, and F is the local extrusion force that the stent can be subjected to after implantation, and F takes a value of 0 N < F ≤ 1 N.

13. The carotid micro mesh braid stent of claim 5, wherein, The second connecting structure (302) is spaced from the end of the support by at least one first intersection, and the second connecting structure (302) is distributed on the end of the support along the second warp (501) or the second weft (502); Or, along the second warp (501) or the second weft (502), the second connecting structure (302) farthest from the support body has an axial distance X from the end of the first support (1) of not more than 2 mm, and the radial projection angle formed by two adjacent second connecting structures (302) and the center of the support cross section is less than or equal to 120°.

14. The carotid micro mesh braid stent of claim 5, wherein, The first connecting structure (301) is distributed in the middle of the support, and the second connecting structure (302) is distributed on the end of the support and along the second warp (501) or the second weft (502), and at least one second connecting structure (302) is arranged near the first connecting structure (301) farthest from the support body.

15. The carotid micro mesh braid stent of claim 1 wherein, The connecting structure (3) further comprises a third connecting structure, and the first support (1) and the second support (2) are tightly connected at the third connecting structure; the third connecting structure is located in the middle region of the first support (1) and is mixedly arranged with the first connecting structure (301); Or, the third connecting structure is located between the region of the first connecting structure (301) and the second connecting structure (302).

16. The carotid micro mesh braid stent of claim 2, wherein, The cavity of the first stent (1) is provided with a buffer hopper (7) which is funnel-shaped as a whole, the buffer hopper (7) is divided into three parts of an expanding end, a body and a tightening end, the buffer hopper (7) is interlaced woven by a plurality of third interlaced wires, the expanding end of the buffer hopper (7) is connected with the first interlaced wire (4) on the first stent (1), the buffer hopper (7) can buffer the blood flow to avoid excessive perfusion.

17. The carotid micro mesh braid stent of claim 16, wherein, The tightening end of the buffer hopper (7) is provided with a plurality of expanding slits (8) which are annularly distributed, so that after the patient adapts to the increase of the blood flow, the buffer hopper (7) gradually reduces the obstruction to the blood flow, thereby ensuring the blood supply.

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