Disclosure of Invention
In view of the above, the present application provides a double-layer braided stent, comprising a braided main body, wherein the braided main body has a double-layer structure and comprises an inner layer tube and an outer layer tube, and the outer layer tube is sleeved on the periphery of the inner layer tube; the outer layer tube is provided with more than two first braiding wires along a first direction, more than two second braiding wires along a second direction, and the first braiding wires and the second braiding wires are interwoven along a first preset angle; the braiding wires of the inner layer pipe and the adjacent first braiding wires and/or second braiding wires are mutually wound and fixed at the end part of the braiding main body; the outer tube is provided with a cross-weave structure disposed between at least partially adjacent first weave filaments and/or between at least partially adjacent second weave filaments.
In one possible implementation, the braided body is divided in its axial direction into a proximal delivery segment, a middle choke segment and a distal opening segment; the braiding wires of the inner layer tube are twisted with the braiding wires of the outer layer tube on the proximal end side of the middle flow blocking section, and the twisting part is the proximal end conveying section; the braiding wires of the inner layer tube are twisted with the braiding wires of the outer layer tube at the far end side of the middle flow blocking section, and the twisting part is the far end opening section; the braiding layers of the outer layer pipe and the inner layer pipe are arranged in staggered layers at the middle flow blocking section.
In one possible implementation, the end of the woven body is provided with a developing tip.
In one possible implementation manner, one strand of the cross-knitting structure is that two cross-knitting wires cross along a first direction for a plurality of times to form a plurality of first crossing points, and the second knitting wires are arranged between two adjacent first crossing points in a penetrating manner, or two cross-knitting wires cross along a second direction for a plurality of times to form a plurality of second crossing points, and the first knitting wires are arranged between two adjacent second crossing points in a penetrating manner.
In one possible implementation manner, two adjacent first braiding wires are arranged in a crossing manner along the first direction, and the structure of the two adjacent first braiding wires is the same as that of the crossing braiding structure; the two adjacent second braiding wires are arranged in a crossing way along the second direction, and the structure of the two adjacent second braiding wires is the same as the crossed braiding structure.
In one possible implementation, the braiding direction of the braiding wires in the inner tube is the same as the braiding direction of the braiding wires in the outer tube; the inner layer tube is provided with more than two third braiding wires along a first direction, more than two fourth braiding wires along a second direction, and the third braiding wires and the fourth braiding wires are interwoven along a first preset angle.
In one possible implementation manner, the knitting yarn arranged along the first direction and the knitting yarn arranged along the second direction are knitting yarns in different directions, and the intersection knitting structure and the position where the intersection knitting structure and the knitting yarn in the different directions intersect are interweaving points; the number of the first intersecting points or the number of the second intersecting points of one strand of the cross-woven structure is smaller than or equal to the number of the interweaving points of the cross-woven structure and the braided wires in different directions.
In one possible implementation, the number of pores per unit area of the inner tube is greater than or equal to 60 pores per mm2.
In one possible implementation, the woven body is integrally formed.
In one possible implementation, the sum of the numbers of braided filaments used for the inner and outer tubes is z, z=24+6k, where k is a natural number.
In one possible implementation, the number of braiding filaments used for the outer tube is m, m=z-12 c, where c is a positive integer; the number of the first braiding wires is the same as the number of the second braiding wires, and the number of the cross braiding wires in the first direction is the same as the number of the cross braiding wires in the second direction.
In one possible implementation, the number of the cross-woven structures is s, s=m/r, where r is a positive even number, r.ltoreq.m.
In one possible implementation, the cross-weave structure is uniformly laid over the outer tube.
In one possible implementation, the material of the braided wire is nickel-titanium material containing a developing material or cobalt-chromium material containing a developing material.
In one possible implementation manner, the outer layer tube is woven by nickel-titanium woven wires and platinum woven wires in a mixed mode, or the outer layer tube is woven by cobalt-chromium woven wires and the platinum woven wires in a mixed mode; the inner layer tube is woven by nickel-titanium woven wires and platinum woven wires in a mixed mode, or the inner layer tube is woven by cobalt-chromium woven wires and platinum woven wires in a mixed mode; two kinds of knitting yarns with different materials are uniformly distributed in the circumferential direction of the knitting main body respectively.
In one possible implementation, when the outer tube is woven by nickel-titanium woven wire or cobalt-chromium woven wire and the platinum woven wire, the wire diameter of the platinum woven wire is larger than the wire diameter of the nickel-titanium woven wire or the cobalt-chromium woven wire.
In one possible implementation, the relation between the number of filament heads x of the nickel titanium braided wire or the cobalt chromium braided wire and the number of filament heads y of the platinum braided wire is x=l×y, where l is a positive integer, l is less than or equal to 48.
In one possible implementation, the outer diameter of the braided body is 1.5mm-7mm and the axial length of the braided body is 10mm-70mm.
In one possible implementation, the braided filaments have a filament diameter in the range of 20 μm to 100 μm.
In one possible implementation, the first preset angle is between 20 ° and 160 °.
In one possible implementation, both ends of the braided body have flared structures.
In one possible implementation, the woven body has a different pore density; wherein the braided body comprises a dense braided section and at least one sparse braided section; the dense braid segment has a void density greater than the void density of the sparse braid segment.
On the other hand, the application also discloses a double-layer braided stent with fixed ends, which comprises a braided main body; the braided support is of a double-layer braided structure and comprises an inner layer pipe and an outer layer pipe, and the outer layer pipe is sleeved on the periphery of the inner layer pipe; the braiding wires of the inner layer tube and the braiding wires of the outer layer tube are mutually wound and fixed at the end part of the braiding main body, and both ends of the braiding main body are of a closed twisting structure; the braiding wires of the inner layer tube and the braiding wires of the outer layer tube adjacent to the braiding wires are twisted and fixed at the two ends of the braiding main body in the same direction or opposite directions to form a closed twisting structure.
In one possible implementation, the braided body is divided in its axial direction into a proximal delivery segment, a middle choke segment and a distal opening segment; the braiding wires of the inner layer tube are twisted with the braiding wires of the outer layer tube on the proximal end side of the middle flow blocking section, and the twisting part is the proximal end conveying section; the braiding wires of the inner layer tube are twisted with the braiding wires of the outer layer tube at the far end side of the middle flow blocking section, and the twisting part is the far end opening section; the braiding layers of the outer layer pipe and the inner layer pipe are arranged in staggered layers at the middle flow blocking section.
In one possible implementation manner, in the proximal conveying section, the braiding wires of the inner layer tube and the first braiding wires and/or the second braiding wires adjacent to the braiding wires are twisted and fixed at two end positions of the braiding main body in the same direction or opposite directions to form a closed twisting structure; or in the proximal conveying section, part of the braiding wires of the inner layer tube and the first braiding wires and/or the second braiding wires are twisted and fixed at the two ends of the braiding main body in the same direction or opposite directions to form a semi-closed twisting structure.
In one possible implementation, the closed twist structure or the closed loop structure is twisted at the proximal or distal end of the braided body in 3, 4, 6, 8, 10 or 12 strands.
In one possible implementation, at least the distal end of the braided body is a closed loop structure, and the braided filaments are bent arcuately at the end of the braided body to form the closed loop structure.
In one possible implementation manner, when the braiding main body has the closed twisting structure or the closed wrapping structure, two adjacent closed twisting structures are arranged in a staggered manner along the circumferential direction of the braiding main body; or two adjacent closed winding structures are arranged in a staggered manner along the circumferential direction of the braiding main body.
The application has the beneficial effects that: the outer layer tube is sleeved on the periphery of the inner layer tube, the braiding wires of the two-layer structure are fixed at two ends of the outer layer tube, so that a double-layer braiding support with stable inner and outer layer structures is formed, and cross braiding is further carried out in the braiding structure of the outer layer tube, so that the end part of the braiding main body forms a special cross braiding structure on the outer layer tube, namely, the braiding wires in different directions (namely, a first braiding wire in a first direction and a second braiding wire in a second direction) generate additional crossing points, friction force among a plurality of wires is increased, and therefore the integral radial supporting force of the braiding main body is improved, and the double-layer braiding support has better mechanical properties. In short, by adding the cross braiding structure compared with the conventional braiding mode, the number of the crossing points of the braiding wires in the outer layer tube is reasonably increased, but the method of the total number of the braiding wires is not changed, so that the radial force of the braided stent is increased, and the possibility of stenosis complications in the stent can be effectively avoided.
Moreover, through setting up the main part of weaving into bilayer structure, compare in single-layer support structure, under the circumstances that braided wire number, metal coverage rate and porosity are the same, its length that contracts in the axial is about half of single-layer support structure, and the easy art person is in the position release of art, and the release position of support is easier to control, reduces the operation degree of difficulty that the art person implemented the operation.
Other features and aspects of the present application will become apparent from the following detailed description of exemplary embodiments, which proceeds with reference to the accompanying drawings.
Detailed Description
Various exemplary embodiments, features and aspects of the application will be described in detail below with reference to the drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. Although various aspects of the embodiments are illustrated in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated.
It should be understood, however, that the terms "center," "longitudinal," "transverse," "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counter-clockwise," "axial," "radial," "circumferential," and the like indicate or are based on the orientation or positional relationship shown in the drawings, and are merely for convenience of describing the application or simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the application.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present application, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
The word "exemplary" is used herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.
In addition, numerous specific details are set forth in the following description in order to provide a better illustration of the application. It will be understood by those skilled in the art that the present application may be practiced without some of these specific details. In some instances, well known methods, procedures, components, and circuits have not been described in detail so as not to obscure the present application.
FIG. 1 shows a schematic diagram of a double-layered braided stent in an aneurysmal vessel according to an embodiment of the present application; FIG. 2 shows a schematic side view of a double-woven stent according to an embodiment of the application; FIG. 3 illustrates a side partial enlarged view of an end of a double-layered braided stent in a closed twist configuration in accordance with an embodiment of the application; FIG. 4 is an axial view of the embodiment shown in FIG. 3; FIG. 5 shows a side partial enlarged view of an end portion of a double-layered braided stent in a closed loop configuration in accordance with an embodiment of the application with an end portion flared; FIG. 6 is an axial view of the embodiment shown in FIG. 5; FIG. 7 illustrates a close-up view of a double-woven stent with end portions of the closed twist structure in a staggered arrangement in accordance with an embodiment of the application; FIG. 8 illustrates a partial enlarged view of a semi-closed twist structure with end portions of a double woven stent in a staggered arrangement in accordance with an embodiment of the present application; FIG. 9 shows an enlarged partial view of a closed loop structure with end portions of a double woven stent in a staggered arrangement in accordance with an embodiment of the present application; FIG. 10 shows a schematic structural view of a double-layered woven stent having woven layers of different pore densities according to an embodiment of the application; FIG. 11 is a schematic cross-sectional view showing a double-layer woven stent in which an outer layer tube is woven with different materials of woven filaments according to an embodiment of the present application; FIG. 12 is a schematic side view showing the structure of the cross-weave structure of an outer layer tube according to an embodiment of the application; fig. 13 is a schematic side view showing a side structure of an outer tube according to another embodiment of the present application; FIG. 14 illustrates a partial enlarged view of a cross-weave structure according to an embodiment of the application; FIG. 15 shows a partial schematic view of a cross-weave structure according to a first embodiment of the application; fig. 16 shows a partial schematic view of a cross-weave structure according to a second embodiment of the application fig. 17 shows a partial schematic view of a cross-weave structure according to a third embodiment of the application;
FIG. 18 illustrates a partial schematic view of the cross-weave structure of FIG. 12 in accordance with the application; FIG. 19 shows a partial schematic view of a cross-weave structure according to a fourth embodiment of the application; FIG. 20 shows a partial schematic view of a cross-weave structure according to a fourth embodiment of the application, on the side of an outer tube; FIGS. 21a, 21b show schematic views of different welding patterns of the ends of a double-layered woven stent according to the present application; FIG. 22 shows a partial schematic view of a braided wire of an embodiment of the application in preparing a closed loop structure at the end of a mandrel.
As shown in fig. 1 to 22, the double-layer braided stent comprises a braided main body 100, wherein the braided main body 100 has a double-layer structure and comprises an inner layer tube 111 and an outer layer tube 101, and the outer layer tube 101 is sleeved on the periphery of the inner layer tube 111; the outer tube 101 is provided with more than two first braiding wires 1011 along a first direction and more than two second braiding wires 1012 along a second direction, the first braiding wires 1011 and the second braiding wires 1012 being interwoven along a first preset angle; the braiding wires of the adjacent inner tube 111 are fixed to both ends of the braiding body 100 with the first braiding wires 1011 and/or the second braiding wires 1012; the outer tube 101 has disposed thereon a cross-braid structure 102, the cross-braid structure 102 being disposed between at least partially adjacent first braid wires 1011 and/or the cross-braid structure 102 being disposed between at least partially adjacent second braid wires 1012.
In this embodiment, the double-layered braided stent in which the inner and outer layer structures are stable is constructed by fitting the outer layer tube 101 around the outer periphery of the inner layer tube 111 and fixing the braided wires of the two-layered structure at both ends thereof. In addition, the application also carries out cross braiding in the braiding structure of the outer layer pipe 101, and forms a special cross braiding structure 102 on the outer layer pipe 101, so that braiding wires in different directions (namely, a first braiding wire 1011 in a first direction and a second braiding wire 1012 in a second direction) generate additional crossing points 201, and friction force among a plurality of wires is increased, thereby improving the whole radial supporting force of the braiding main body 100, and leading the double-layer braiding bracket of the application to have better mechanical property. In short, the method of increasing the number of the crossing points 201 of the braiding wires in the outer layer tube 101 without changing the number of the braiding wires improves the radial force of the braiding stent, can effectively avoid the possibility of stenosis complication in the stent, and has certain advantages for treating the hemorrhagic aneurysm 500 diseases in clinic.
Moreover, compared with a single-layer support structure, the double-layer braided support has the advantages that the axial shortened length is only about half of that of the single-layer support structure under the condition that the number of braided wires, the metal coverage rate and the porosity are the same, so that the double-layer braided support is easy for an operator to position and release in an operation, the release position of the support is easier to control, and the operation difficulty of the operation is reduced.
More specifically, when the stent is pressed into the introducer sheath, the compression state stent is more easily shortened than the traditional single-layer stent in terms of the shortening degree of the stent, so that the stent has remarkable help to reduce the conveying resistance of an operator in clinic, and in addition, the double-layer braided stent has the metal coverage rate which is 1.0 times or more than that of the traditional stent, so that the stent can improve the compact blocking of the tumor neck and guide the blood flow trend. In sum, in the double-layer braided stent, the outer layer tube 101 is provided with the cross-braided structure 102, so that the stent has the remarkable characteristics of high radial supporting force, high metal coverage rate and low shrinkage rate, has higher blood flow guiding capability, and has certain advantages for treating hemorrhagic aneurysm 500 diseases in clinical use.
It should be specifically explained that the double-layer braided stent of the present application has a uniform metal coverage and porosity and is braided to the same axial length as a conventional single-layer braided stent, and each braided wire of the double-layer braided stent is wound in the circumferential direction with a smaller wire length than that of the single-layer braided stent; so that the total length of the double-layer braided stent is smaller than that of the traditional single-layer braided stent in the lumen compressed into the same inner diameter; based on this, release is in the blood vessel of same diameter, the axial length variation of double-deck support is littleer, and the short volume of shrinking of double-deck establishment support is littleer promptly, and the operator carries out the support release operation, and the variation of support axial length is littleer, and the operator easily holds the release position of support to reduce the operation degree of difficulty that the operator carried out the operation.
The preset angle α between the first direction and the second direction referred to herein is: when the outer tube 101 is unfolded in a plane, the first knitted filaments 1011 in the first direction form an angle with the second knitted filaments 1012 in the second direction. Twist is herein intended to be: and winding and binding two or more adjacent braided wires.
Further, the braid wires of the adjacent inner tube 111 are fixed to both ends of the braid body 100 with the first braid wires 1011 and/or the second braid wires 1012. The axial lengths of the inner layer tube 111 and the outer layer tube 101 are the same, and the braiding wires of the inner layer tube 111 and the braiding wires of the outer layer tube 101 are fixed at the two ends of the braiding main body 100, so that the inner layer tube 111 and the outer layer tube 101 do not displace in the axial direction of the braiding main body 100, a plurality of connection points between the inner layer tube 111 and the outer layer tube 101 are ensured, and the overall structure is more stable.
In one embodiment, the braided filaments of the inner tube 111 and the braided filaments of the outer tube 101 adjacent thereto are twisted around each other at the end of the braided body 100 to form a closed end at the end of the braided body 100.
In one embodiment, the woven body is integrally formed.
In this embodiment, the yarn carrier for processing the inner layer tube and the yarn carrier for processing the outer layer tube are simultaneously woven from the same side of the weaving mandrel, so as to prepare a double-layer weaving support for twisting and fixing the inner layer tube and the outer layer tube at the end, and the specific processing mode can be realized by those skilled in the art directly using the prior art, so that the description thereof is omitted herein.
In one embodiment, one strand of the cross-woven structure 102 is formed by multiple crossing of two cross-woven wires along a first direction to form multiple first crossing points 2011, and the second woven wire 1012 is threaded between two adjacent first crossing points 2011, or multiple crossing of two cross-woven wires along a second direction to form multiple second crossing points 2012, and the first woven wire 1011 is threaded between two adjacent second crossing points 2012.
In this embodiment, the cross-woven structure 102 in the outer tube 101 of the present application has more cross points 201 formed by the cross-woven wires than the conventional stent woven structure with the same number of woven wires, so that the radial force of the whole formed stent is effectively improved, the stent is easier to open in the arterial vessel 400, the attachment and anchoring effects are better, and the kink resistance is better.
It should be specifically noted that, the intersection point 201 is two intersecting braided wires arranged in the same direction, and the intersection point is the intersection point 201 by alternating the upper and lower relationship of the intersecting braided wires; further, the interweaving points 202 referred to herein are all points of intersection where the cross-woven structure 102 intersects with one braided wire in an opposite direction.
In one specific embodiment, the braiding direction of the braiding wires in the inner tube 111 is the same as the braiding direction of the braiding wires in the outer tube 101, wherein the inner tube 111 is provided with more than two third braiding wires 1111 in the first direction, more than two fourth braiding wires 1112 in the second direction, and the third braiding wires 1111 and the fourth braiding wires 1112 are interwoven in the first preset angle. The inner tube 111 is generally woven by a conventional method, and only two ends of the inner tube are twisted and fixed with the outer tube 101, so that the inner tube 111 will not be described in detail herein.
In this embodiment, therefore, the predetermined angle α is: when the outer tube 101 is unfolded in a plane, the first knitted wire 1011 in the first direction and the second knitted wire 1012 in the second direction form an angle; and an angle formed between the third knitted yarn 1111 in the first direction and the fourth knitted yarn 1112 in the second direction when the inner tube 111 is unfolded in a plane. The knitting structure of the inner tube 111 and the knitting structure of the outer tube 101 are identical to each other, except that the surface of the outer tube 101 has the cross knitting structure 102, and the knitting structures of the inner tube 111 and the outer tube 101 are identical to each other.
In one embodiment, the total number of braided filaments on the outer tube 101 is an even number; the number of the first knitting yarn 1011 and the number of the second knitting yarn 1012 are the same, and the number of the intersecting knitting yarn in the first direction and the number of the intersecting knitting yarn in the second direction are the same.
In this embodiment, the distribution of the cross-woven structure 102 determines the number of cross-points 201 of the outer tube 101, i.e. the radial force of the stent. The distribution of the cross-weave structures 102 in the stent may be varied, desirably, the outer tube 101 has a weave wire count of m=2n, where m is an even number greater than or equal to 4, and n is the weave wire count in one of the first and second directions in the stent.
In one embodiment, the cross-weave structure 102 is uniformly distributed over the outer tube 101.
In one embodiment, as shown in fig. 12, the number of strands of the cross-weave structure 102 is generally even and may be two strands evenly distributed over the outer tube 101 (as shown in fig. 12).
As shown in fig. 13, the two cross-braid wires in cross-braid structure 102 may be crossed in such a way that one is over and the other is under; or one can be under and the other can be on top. The braiding track of the braiding wires around the circumference of the stent is a cycle, and in the cycle, two crossed braiding wires can form a multi-time crossed braiding structure 102 according to a certain distribution rule.
In one particular embodiment, the spacing between two first filaments 1011 or two second filaments 1012 provided with the cross-woven structure 102 is greater than the spacing between the remaining adjacent filaments.
In one embodiment, the braiding wires arranged in the first direction and the braiding wires arranged in the second direction are braiding wires in different directions from each other, and the intersection point 202 is the intersection point of the cross-braiding structure 102 and the braiding wires in the different directions; the number of first crossover points 2011 or the number of second crossover points 2012 of a strand of cross-woven structure 102 is equal to or less than the number of interweaving points 202 of the cross-woven structure 102 with filaments of different directions.
The number of intersecting points 201 at which two intersecting filaments can form an intersecting weave in one cycle is an integer a, and the number of interlacing points 202 between two intersecting filaments and filaments in different directions is b, so that a is not more than b.
As shown in fig. 15, in one embodiment, a=b, that is, two cross-knitting yarns are interwoven with the same knitting yarn in different directions 1 time and then cross-knitting is performed;
As shown in fig. 16, in one embodiment, a=b/2, that is, two cross-knitting yarns are interwoven with the same knitting yarn in different directions 2 times respectively and then cross-knitting is performed;
As shown in fig. 17, in one embodiment, a=b/3, two cross-knitting yarns are interwoven with the same yarn in different directions 3 times, and then the cross-knitting is performed.
Further, two cross-knit wires in the second direction may also form the cross-knit structure 102 simultaneously with two cross-knit wires in the first direction.
In one specific embodiment, a=b/2, two cross-knitting yarns in the first direction and the second direction are interwoven 2 times, and then cross-knitting is performed respectively, so as to form a structure as shown in fig. 18;
In one embodiment, two adjacent first braiding wires 1011 are arranged to cross in a first direction and have the same structure as the cross braiding structure 102; two adjacent second filaments 1012 are arranged crosswise in the second direction and have the same structure as the cross-weave structure 102.
Further, a cross-weave structure 102 may be formed between t sets of weave filaments in the stent, t.ltoreq.n.
In one embodiment, the set of t=b/2 wires in the stent are interwoven with each other and then cross-woven to form the structure shown in fig. 18 and 20, and briefly, fig. 20 is a partial schematic view of the outer tube 101 shown in fig. 18.
As shown in fig. 12, in this embodiment, the first braiding wires 1011 in the first direction and the second braiding wires 1012 in the second direction form a predetermined angle α in the range of 20 ° -160 °.
Further, in one embodiment, in the outer tube 101, the first filaments 1011 in the first direction form the same angle with the axial direction of the knitted body 100 as the second filaments 1012 in the second direction form the same angle with the axial direction of the knitted body 100. In other words, first braid wires 1011 in the first direction and second braid wires 1012 in the second direction are symmetrically disposed along the axis of braid body 100.
In another embodiment, in the inner tube 111, an angle formed between the third filaments 1111 in the first direction and the axial direction of the knitted body 100 and an angle formed between the fourth filaments 1112 in the second direction and the axial direction of the knitted body 100 are symmetrically arranged along the axis of the knitted body 100.
In one embodiment, the woven body 100 is axially divided into a proximal delivery segment 121, a middle flow blocking segment 122, and a distal opening segment 123, the woven filaments of the inner tube 111 are twisted with the woven filaments of the outer tube 101 on the proximal side of the middle flow blocking segment 122, the twisted portion is the proximal delivery segment 121, the woven filaments of the inner tube 111 are twisted with the woven filaments of the outer tube 101 on the distal side of the middle flow blocking segment 122, and the twisted portion is the distal opening segment 123.
In this embodiment, the proximal conveying section 121 and the distal opening section 123 are formed by twisting the braiding wires of the inner tube 111 and the braiding wires of the outer tube 101, so as to ensure that the inner tube 111 and the outer tube 101 are respectively twisted and fixed from the proximal end side and the distal end side, respectively, and the braiding layers of the outer tube 101 and the inner tube 111 located in the middle choke section 122 are arranged in a staggered manner, that is, the braiding wires of the inner tube 111 and the braiding wires of the outer tube 101 are not overlapped in the radial direction of the braiding body 100 at the same position of the side wall of the braiding body 100.
It should be specifically explained here that the braid of the outer tube 101 and the braid of the inner tube 111 are staggered at the position of the middle choke section 122, which means that: in the middle choke section 122 of the knitted body 100, the knitted layer of the inner layer tube 111 is attached to the knitted layer of the outer layer tube 101, and the two knitted layers are staggered and non-overlapped in the circumferential direction of the knitted body 100, and the knitted pores of the knitted body 100 are more dense by the knitted structure of the staggered layers, see fig. 23, so as to realize effective and durable embolization of the aneurysm 500.
More specifically, the inner layer tube 111 and the outer layer tube 101 are arranged in a staggered manner, and only if the braiding directions in the inner layer tube and the outer layer tube are the same (both braiding in the first direction and the second direction), the inner braiding layer and the outer braiding layer can be always kept parallel and always kept in a staggered state, and it can be understood that the staggered braiding bodies 100 are arranged in a staggered manner, and the intersecting points in the inner layer tube 111 and the intersecting points in the outer layer tube 101 are arranged in a staggered manner on the circumferential side surface of the braiding body 100.
Further, compared with a single-layer bracket, the double-layer woven bracket with the staggered arrangement of the inner layer and the outer layer of the double-layer woven bracket has the advantages that the number of turns of the woven wires of each layer around the woven core rod is only half of that of the single-layer woven wires. For example, the single-layer stent is woven for 10 circles around the weaving mandrel 250, and the double-layer woven stent with staggered layers can achieve the same porosity as the single-layer stent by only 5 circles around the weaving mandrel 250, so that the double-layer woven stent is smaller in shrinkage rate on the premise that the axial woven length, the porosity and the metal coverage rate are the same, and then the double-layer woven stent is compressed into a catheter, and the axial total length of the double-layer woven stent is shorter than that of the single-layer stent.
Moreover, double-deck support of weaving, compare in single-layer support structure, under the same circumstances of weaving silk number, its length that shortens in the axial is only about half of single-layer support structure, and the easy art person is in the position release of art, and the release position of support is more easy to control, reduces the operation degree of difficulty of operation.
In one embodiment, the braided filaments of the outer tube 101 and the braided filaments of the inner tube 111 are preferably the same gauge braided filaments, and the wire diameter is in the range of 0.001 inch to 0.004 inch.
In this embodiment, the material of the braided wire may be nickel titanium, cobalt chromium, stainless steel, polymer, tantalum or a mixture thereof.
In one embodiment, the braiding wires of the adjacent inner tube 111 are twisted and fixed with the first braiding wires 1011 and/or the second braiding wires 1012 in the same direction or in opposite directions at both end positions of the braiding body 100 to form a closed twist structure 131.
In one embodiment, the outer diameter of the braided body 100 is between 1.5mm and 7mm, and the two axial side ends of the outer tube 101 are connected by braiding wires to form a closed structure.
As shown in fig. 3,4 and 7, in one embodiment, the braiding wires of the inner tube 111, the first braiding wire 1011 and/or the second braiding wire 1012 adjacent thereto are twisted and fixed in the same direction or opposite directions at both end positions of the braiding body 100 to form a closed twist structure 131.
In one embodiment, for the proximal delivery segment 121, the braided filaments of the inner tube 111 are twisted and fixed in the same direction or opposite directions at both ends of the braided body 100 to form a closed twisted structure 131 with the first braided filaments 1011 and/or the second braided filaments 1012 adjacent thereto; or part of the braiding wires of the inner tube 111 are twisted and fixed with the first braiding wires 1011 and/or the second braiding wires 1012 in the same direction or opposite directions at both end positions of the braiding body 100, thereby forming a semi-closed twisted structure 132.
It should be noted that the distal end of the braided body 100 must be a closed twist 131 or otherwise processed to form an overall distal end with a curved surface to avoid injury to the human body, while the proximal delivery segment 121 does not require excessive protective measures due to its direct contact with the delivery instrument. Only part of the inner and outer braided wires can be twisted and fixed in the same direction or opposite directions to form a semi-closed twisting structure 132, as shown in fig. 8; may also be formed in a closed twist structure 131 consistent with the structure of the distal opening section 123.
In one particular embodiment, when the braided body 100 has a closed twist structure 131, the number of strands of the closed twist structure 131 is 3,4, 6, 8, 10, or 12.
In one embodiment, more than two braided wires are twisted together, and the twisted ends are sleeved with a developing tip 300 and fixed by welding. Similarly, for the semi-closed twisting structure 132, the end of the twisting of more than two filaments is sleeved with the developing tip 300, and the remaining non-twisted filaments are woven in the original direction until cut off.
More specifically, the closed twist structure 131 is: at the beginning or ending of braiding, the total filament head z involved in braiding is first divided into several parts, and the braided filaments in each part are further divided into two bundles which are rotated in the same direction or opposite directions respectively to form stable filament bundles, and then the two filament bundles are bound together in parallel to form the complete closed twist structure 131.
In another embodiment, the semi-closed twist structure 132 consists of: when knitting is started or finished, cutting the equal number of knitting yarns which are uniformly distributed in the circumferential direction and rotate in the same direction or opposite directions in part of the total spinning head z participating in knitting, further dividing the rest of knitting yarns into a plurality of parts, dividing the knitting yarns in each part into two bundles which rotate clockwise and anticlockwise respectively to form stable yarn bundles, and then binding the two yarn bundles together in parallel to form a final semi-closed twisting end.
Further, the single closed twist structure 131 or the single semi-closed twist structure 132 of the double-layered braided stent is typically fixed by welding, and the welding method can be used in fig. 21a or 21b.
In one embodiment, as shown in fig. 5, 6 and 9, at least the distal end of the braided body 100 is a closed loop structure 133, and the braided filaments are bent arcuately at the end of the braided body 100 to form the closed loop structure 133.
More specifically, as shown in fig. 22, one approach to closed loop weave design is to: the braiding mandrel 250 is perforated and fitted with stainless steel nails 251, the braiding wires on the carrier are passed around the stainless steel nails 251 to form a closed loop structure 133, and the braiding wires passed around the stainless steel nails 251 are then connected to another carrier. On this basis, the carrier is woven in accordance with a predetermined trajectory to form a support with a closed loop structure 133 at the end. After braiding to the other end, the braiding mandrel 250 is removed and the braiding wires are manually maneuvered around the stainless steel pins 251 to form another closed loop structure 133.
In one embodiment, when the braiding main body 100 has the closed twisting structure 131 or the closed wrapping structure 133, two adjacent closed twisting structures 131 are arranged in a staggered manner along the circumferential direction of the braiding main body 100; or adjacent two of the closed loop structures 133 are offset in the circumferential direction of the knitted body 100.
In this embodiment, as shown in fig. 7 to 9, adjacent closed structures are offset from each other along the circumferential direction of the stent at the end of the woven main body 100, and when the double-layer woven stent of the present application is compressed, the offset of the end allows a plurality of adjacent closed structures to better yield, so that the stent is easier to compress.
In one embodiment, the sum of the number of braided filaments used for the inner tube 111 and the outer tube 101 is z, z=24+6k, where k is a natural number.
In one embodiment, the number of braiding filaments used in the outer tube 101 is m, m=z-12 c, where c is a positive integer; the number of first braid wires 1011 is the same as the number of second braid wires 1012, and the number of cross braid wires in the first direction is the same as the number of cross braid wires in the second direction.
In one embodiment, the number of cross-woven structures 102 is s, s=m/r, where r is a positive even number and r is less than or equal to m.
In one embodiment, the cross-weave structure 102 is uniformly distributed over the outer tube 101.
In one embodiment, the material of the braided wire is nickel titanium containing a developing material or cobalt chromium containing a developing material.
In this embodiment, the braided wire may be made of nickel-titanium, cobalt-chromium, or other materials with shape memory properties, alone or in combination, and the double-layer stent may be made entirely of platinum-containing nickel-titanium tubes or platinum-containing cobalt-chromium-nickel tubes, so as to achieve the effect of developing the entire stent.
In one embodiment, the outer layer tube 101 is woven by nickel-titanium woven wires and platinum woven wires 1015 in a mixed manner, or the outer layer tube 101 is woven by cobalt-chromium woven wires and platinum woven wires 1015 in a mixed manner, and two woven wires with different materials are respectively uniformly distributed in the circumferential direction of the outer layer tube 101.
In one embodiment, the wire diameter of platinum braid 1015 is greater than the wire diameter of nickel titanium braid or cobalt chromium braid 1016.
Preferably, the number of nickel titanium braid wires or cobalt chromium braid wires 1016 is greater than the number of platinum braid wires 1015.
In this embodiment, the outer layer tube 101 is mixed-woven, and the wire diameter of the platinum braiding wire 1015 is large, so that the attaching area of the outer layer tube 101 and the microcatheter during delivery can be effectively reduced, and the frictional resistance can be reasonably reduced.
In one embodiment, the relationship between the number of filaments x of a nickel titanium braid or cobalt chromium braid and the number of filaments y of a platinum wire is x=l×y, where l is a positive integer and l is less than or equal to 48.
In one embodiment, the outer diameter of the woven body 100 is 1.5mm-7mm and the axial length of the woven body 100 is 10mm-70mm.
In one embodiment, the braided filaments have a filament diameter in the range of 20 μm to 100 μm.
In one embodiment, the ends of the woven body 100 are directed outwardly Zhou Kuokou toward the structure 140.
As shown in fig. 10, in one particular embodiment, the void densities of the braided body 100 are different, wherein the braided body 100 includes a dense braided section 151 and at least one sparse braided section 152; the void density of the densely woven sections 151 is greater than the void density of the sparsely woven sections 152.
In this embodiment, in the case of having a branch vessel 401 beside the location of the arterial vessel 400 where the aneurysm 500 is located, the braided body 100 having different pore densities in the axial direction is used, and the operator needs to ensure that the dense braided section 151 is released to the location of the aneurysm 500 during the operation of releasing the double stent of the present application, and accordingly, the sparse braided section 152 reduces the influence on the blood flow of the branch vessel 401.
More specifically, the number of the sparse braiding segments 152 may be one, or the sparse braiding segments 152 may be disposed on two sides of the dense braiding segment 151 according to specific situations such as a disease position, and a person skilled in the art may prepare a double-layer braiding stent more fitting the current scheme according to the above thought and specific situations, so that the present invention is not limited too much.
It is also to be appreciated that the void density of the woven body 100 referred to herein is: the braid of the outer tube 101 and the braid of the inner tube 111 are superimposed at corresponding positions, and then collectively constitute the pore density of the entire braided body 100.
The foregoing description of embodiments of the application has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the various embodiments described. The terminology used herein was chosen in order to best explain the principles of the embodiments, the practical application, or the improvement of technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.