Stent and method of making a stent

Abstract

The application provides a stent and a stent manufacturing method. The stent comprises a plurality of grid segments and a plurality of connecting segments. The grid segment comprises a plurality of grid units connected in a circumferential direction. Each grid unit comprises a plurality of grid rods. The connecting segment comprises a plurality of connecting rods. The connecting rods are used to connect axially adjacent grid units. The connecting rods comprise first connecting rods. The Af phase transition temperature of the first connecting rods is greater than the Af phase transition temperature of the grid rods. The Af phase transition temperature of at least part of the connecting rods of the stent is greater than the Af phase transition temperature of the grid rods of the grid units connected by the connecting rods. At least part of the connecting rods of the connecting segment has excellent bending performance. The stent has a retractable performance and good flexibility. The technical problem of collapse deformation of the stent during retraction is solved.

Description

Technical Field

[0001] This invention belongs to the field of medical device technology, and more specifically, relates to a stent and a method for manufacturing the stent. Background Technology

[0002] In minimally invasive surgery, a delivery device is used to transport a stent through an incision on the surface of the body to its target location inside the body (such as a blood vessel, valve, or sinus). The sheath that holds the stent is then retracted to release it. During stent release, due to various reasons, it may be necessary to retract the partially released stent back into the sheath before re-release. This places new structural requirements on stents.

[0003] Traditional retractable supports, as shown in Chinese patent documents CN109172040A and CN109700582A, only add a retraction structure to one end of the non-retractable support, and attempt to retract the support into the conveying device by pulling, tugging, or dragging the retractable structure. However, in actual operation, as... Figure 1 As shown, when the structure 6 is pulled back to the proximal end, its open loop point and the unpulled vertex will tilt up during the retraction compression process because they are not bound by the traction force, and get stuck at the entrance of the sheath tube 5, making it difficult for the stent to achieve true retraction.

[0004] Therefore, there is a need in the art for a new type of support that can be smoothly retracted into the conveying device. Summary of the Invention

[0005] The purpose of this invention is to provide a stent and a stent manufacturing method to solve the technical problem of stents being difficult to retract in the prior art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of the present invention provides a support, including multiple grid segments and multiple connecting segments. The grid segments include multiple grid units connected in a circumferential direction. Each grid unit includes multiple grid rods. The connecting segments include multiple connecting rods. The connecting rods are used to connect axially adjacent grid units. Each connecting rod includes a first connecting rod, and the Af phase transition temperature of the first connecting rod is greater than the Af phase transition temperature of the grid rod.

[0007] In one embodiment, the grid cell is either closed or open.

[0008] In one embodiment, the grid cell is a polygon or a circle, or the grid cell is wavy or serrated.

[0009] In one embodiment, the number of the first connecting rods in each grid segment accounts for more than 5% of the total number of connecting rods.

[0010] In one embodiment, the difference between the Af phase transition temperature of the first connecting rod and the Af phase transition temperature of the mesh rod is greater than or equal to 4°C.

[0011] A second aspect of the present invention provides a support, comprising multiple grid segments and multiple connecting segments. Each grid segment comprises multiple circumferentially connected grid units, and each connecting segment comprises a first connecting rod and a second connecting rod. Both the first connecting rod and the second connecting rod are used to connect axially adjacent grid units. The Af phase transition temperature of the first connecting rod is different from that of the second connecting rod.

[0012] In one embodiment, the ratio of the number of first connecting rods to the number of second connecting rods in each connecting segment is greater than 1:19 and less than 19:1.

[0013] In one embodiment, the difference between the Af phase transition temperature of the first connecting rod and the Af phase transition temperature of the second connecting rod is greater than or equal to 4°C.

[0014] A third aspect of the present invention provides a method for manufacturing a support, comprising:

[0015] The metal tubing is fabricated into a bare support, which includes multiple grid segments and multiple connecting segments. Each grid segment includes multiple grid units connected circumferentially. Each grid unit includes multiple grid rods. Each connecting segment includes multiple connecting rods, which are used to connect axially adjacent grid units.

[0016] The bare support is heat-treated, wherein at least a portion of the connecting rods in the connecting segment are subjected to a lower temperature during heat treatment than the mesh rods in the mesh segment, so as to obtain a first connecting rod with an Af phase transition temperature greater than that of the mesh rod.

[0017] In one embodiment, the bare support is heat-treated, wherein during the heat treatment, the temperature of at least a portion of the connecting rods in the connecting segment is lower than the temperature of the mesh rods in the mesh segment, in order to obtain a first connecting rod with an Af phase transition temperature greater than that of the mesh rods, the step includes:

[0018] A thermally insulating sheath is provided, wherein the sheath has a protective portion having a groove for receiving the connecting rod;

[0019] The sheath is disposed on the connecting section, wherein the groove accommodates the connecting rod for preparing the first connecting rod, so as to reduce the temperature of the accommodated connecting rod during the heat treatment process.

[0020] In one embodiment, the sheath is annular to be fitted onto the bare support.

[0021] The sheath also includes a connecting portion for connecting the protective portion, and the connecting portion has a hollow structure for covering the connecting rod not accommodated by the groove, so that the temperature of this part of the connecting rod is higher than the temperature of the connecting rod used to make the first connecting rod during heat treatment.

[0022] In one embodiment, the bare bracket with the sheath is heat-set at 480-520°C for 1-2 minutes, then quenched and the process is repeated 4-6 times.

[0023] In one embodiment, when heat-treating the bare support, wherein at least a portion of the connecting rods in the connecting segment are at a lower temperature than the mesh rods in the mesh segment during the heat treatment, to obtain a first connecting rod with an Af phase transition temperature greater than that of the mesh rods, a first mandrel with a diameter equivalent to that of the support is first inserted into the bare support with the sheath, so as to expand the bare support to the diameter of the support.

[0024] In one embodiment, during heat treatment, the temperature of the connecting rod used to prepare the first connecting rod is more than 30°C lower than the temperature of the mesh rod of the mesh segment during heat treatment.

[0025] In one embodiment, the diameter of the bare support is smaller than the diameter of the support. After the metal tube is made into a bare support, the process further includes: inserting a second mandrel with a diameter smaller than the diameter of the support but larger than the diameter of the bare support into the bare support to pre-expand the diameter of the bare support, then performing heat setting, and then taking it out for quenching.

[0026] In one embodiment, after heat treatment of the bare support, wherein at least a portion of the connecting rods in the connecting segment are at a lower temperature than the mesh rods in the mesh segment during heat treatment, to obtain a first connecting rod with an Af phase transition temperature greater than that of the mesh rods, the support is further polished.

[0027] The fourth aspect of the present invention provides a method for manufacturing a support, comprising: manufacturing a bare support from a metal tube, the bare support comprising a plurality of grid segments and a plurality of connecting segments, the grid segments comprising a plurality of grid units connected sequentially in a circumferential direction, the connecting segments comprising a plurality of connecting rods, the connecting rods being used to connect the grid units that are axially adjacent;

[0028] The bare support is subjected to heat treatment, wherein during the heat treatment, the temperature of the connecting rod used to prepare the first connecting rod in the connecting segment is different from the temperature of the connecting rod used to prepare the second connecting rod, so that the Af phase transition temperature of the first connecting rod is different from the Af phase transition temperature of the second connecting rod.

[0029] The support provided by this invention includes multiple grid segments and multiple connecting segments. Each grid segment comprises multiple circumferentially connected grid units, and each grid unit includes multiple grid rods. Each connecting segment includes multiple connecting rods for connecting axially adjacent grid units. Each connecting rod includes a first connecting rod, whose Af phase transition temperature is greater than that of the grid unit, or its Af phase transition temperature differs from that of the remaining connecting rods in the connecting segment. Because the grid units in the support of this invention are circumferentially connected and axially connected to each other via connecting rods, and because the first connecting rods in at least some connecting segments have different heat treatment environments than the rest of the support, these first connecting rods exhibit superior bending performance. Furthermore, the Af phase transition temperature of the first connecting rods in at least some connecting segments is greater than that of the rest of the support, giving the support good flexibility and allowing it to be smoothly retracted into a sheath. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the retraction stent in the prior art of the present invention;

[0032] Figure 2 This is a schematic diagram of the structure of the bracket in one embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the structure of the bracket in another embodiment of the present invention;

[0034] Figure 4 This is a schematic diagram of the structure of the sheath in one embodiment of the present invention;

[0035] Figure 5 A schematic diagram of a support structure with a protective sleeve during heat treatment in one embodiment of the present invention;

[0036] Figure 6 A schematic diagram of the bracket during a bending performance test in one embodiment of the present invention;

[0037] Figure 7 This is a schematic diagram of a stent during a vascular compliance test in one embodiment of the present invention. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] In the description of this invention, it should be understood that the terms “comprising” and “having” as used herein, and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0040] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0041] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0042] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. It should be understood that the term "and / or" as used herein is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone.

[0043] The inventors discovered that traditional retractable stents, which are designed as fully closed-loop structures (connecting each grid segment to its circumferentially adjacent grids and to its axially adjacent grids via connecting rods), cannot achieve smooth retraction. This design reduces the stent's flexibility, leading to collapse and deformation during retraction, hindering further release and potentially damaging the stent. Furthermore, the inventors found that by giving at least some connecting rods in the connecting segments better bending performance—for example, by ensuring that at least some connecting rods in the connecting segments are heated to a lower temperature than other parts—the stent achieves better flexibility, resulting in smoother retraction. Simultaneously, these connecting rods have a higher Af phase transition temperature compared to other parts of the stent.

[0044] Based on the above findings, the present invention provides a support, comprising multiple grid segments and multiple connecting segments. Each grid segment comprises multiple circumferentially connected grid units, and each grid unit comprises multiple grid rods. Each connecting segment comprises multiple connecting rods, which are used to connect axially adjacent grid units. Each connecting rod includes a first connecting rod, and the Af phase transition temperature of the first connecting rod is greater than the Af phase transition temperature of the grid unit.

[0045] Based on the above findings, the present invention also provides a support, including multiple grid segments and multiple connecting segments. The grid segments include multiple grid cells connected in sequence in the circumferential direction. The connecting segments include a first connecting rod and a second connecting rod. Both the first connecting rod and the second connecting rod are used to connect axially adjacent grid cells. The Af phase transition temperature of the first connecting rod is different from that of the second connecting rod.

[0046] This invention does not impose any particular limitations on the type or application of the stent. For example, the stent in this embodiment can be a coronary stent, a cerebral vascular stent, an abdominal aortic stent, a femoral artery stent, a valve stent, an external iliac artery stent, etc.

[0047] The bracket and bracket manufacturing method provided by the present invention will be described in detail below with reference to specific embodiments.

[0048] Example 1:

[0049] Figure 2 This is a schematic diagram of the structure of the bracket provided in an embodiment of the present invention. Please refer to [link / reference]. Figure 2 As shown, this embodiment provides a support, which includes multiple grid segments 1 and multiple connecting segments 2. The grid segment 1 includes multiple grid units 11 connected in a circumferential direction. Each grid unit 11 includes multiple grid rods 111. The connecting segment 2 includes multiple connecting rods. The connecting rods are used to connect axially adjacent grid units 11. The connecting rods include a first connecting rod 211. The Af phase transition temperature of the first connecting rod 211 is greater than the Af phase transition temperature of the grid rod 111.

[0050] In this embodiment, multiple mesh cells 11 are connected sequentially in a circumferential direction, or multiple mesh cells 11 can be directly connected, for example... Figure 2 As shown, two circumferentially adjacent grid cells 11 are directly connected by sharing a single grid pole; alternatively, multiple grid cells 11 can be indirectly connected, for example, two circumferentially adjacent grid cells 11 can be connected by a connector.

[0051] This embodiment does not impose any particular limitation on the number of grid segments 1. Figure 2 In the scaffold shown, there are 6 grid segments 1. In other embodiments, the number of grid segments 1 may be less than 6, such as 2, 3, 4, or 5; the number of grid segments 1 may also be greater than 6, such as 7 or 8. Those skilled in the art can determine the number of grid segments 1 based on the anatomical characteristics of human tissues and the disease to be addressed.

[0052] Similarly, this embodiment does not impose a particular limitation on the number of grid cells 11 contained in each grid segment 1. The number of grid cells 11 contained in each grid segment 1 of each support can be the same or not exactly the same. Figure 2 In the illustrated support structure, each grid segment 1 contains the same number of grid cells 11, specifically 12 grid cells 11. In other embodiments, the number of grid cells 11 contained in each grid segment 1 may be less than 12 or more than 12. In other embodiments, the number of grid cells 11 in the grid segments 1 at both ends of the support structure is less than the number of grid cells 11 in the grid segments 1 in the middle of the support structure; in yet another embodiment, the number of grid cells in the grid segments 1 at both ends of the support structure is greater than the number of grid cells in the grid segments 1 in the middle of the support structure.

[0053] This embodiment does not impose any particular restrictions on the shape of the grid unit 11. The grid unit 11 can be a closed shape, that is, a single grid rod connected end to end, or multiple grid rods connected sequentially, with the first and last grid rods also connected to each other. Figure 2The grid unit 11 shown is a closed hexagonal shape. Specifically, the hexagonal grid unit 11 includes six rods 111 connected end-to-end. Two rods 111 are parallel to the axis of the support, and one end of the other four rods 111 is connected to the two ends of the first two rods, with the opposing rods 111 being approximately parallel to each other. The other ends of the other four rods 111 connect to form vertices. The two ends of the connecting rod of the connecting segment 2 are connected to the vertices of one grid unit 11. Furthermore, adjacent grid units 11 in the circumferential direction can share a single rod. In other embodiments, the grid unit 11 can also be other closed shapes, such as triangles, rhombuses, pentagons, or other polygons, circles, or ellipses. In other embodiments, the grid unit 11 can be an open shape, such as a zigzag, wavy, or spiral shape. The rods constituting the open-shaped grid unit 11 are connected sequentially, but the first and last rods are not connected.

[0054] In this embodiment, the connecting segment 2 is used to connect axially adjacent grid segments 1. Therefore, the number of connecting segments 2 is determined according to the number of grid segments 1. Figure 2 In the bracket shown, there are 5 connecting segments 2, so that each of the 6 grid segments 1 is connected to the adjacent grid segment 1.

[0055] Similarly, the number of connecting rods in connecting segment 2 is also determined by the number of grid cells 11 in grid segment 1. Figure 2 In the illustrated support structure, each grid segment 1 contains 12 grid cells, and consequently, the connecting segment 2 also contains 12 connecting rods, so that each grid cell 11 is connected to an axially adjacent grid cell 11 via a connecting rod. In other embodiments, the number of grid cells 11 in each grid segment 1 is greater than or less than 12, and the number of connecting rods in the connecting segment 2 is also greater than or less than 12. In other embodiments, the number of grid cells 11 in adjacent grid segments 1 is not equal, and the number of connecting rods depends on the number of grid cells in the grid segment 1 with more grid cells 11. Therefore, in grid segments 1 with fewer grid cells 11, some vertices of some grid cells 11 may be connected to multiple connecting rods.

[0056] The connecting rod includes a first connecting rod 211. In this embodiment, the number of first connecting rods 211 is not particularly limited. Figure 2 In the bracket shown, all connecting rods in connecting segment 2 are first connecting rods 211. In other embodiments, the number of first connecting rods 211 in each connecting segment 2 accounts for more than 5% of the total number of connecting rods. Preferably, the number of first connecting rods 211 accounts for more than 20% of the total number of connecting rods. More preferably, the number of first connecting rods 211 accounts for more than 50% of the total number of connecting rods.

[0057] Preferably, the first connecting rods 211 are evenly distributed around the circumference of the bracket. This allows the bracket to provide sufficient radial support while maintaining good flexibility.

[0058] Preferably, the difference between the Af phase transition temperature of the first connecting rod 211 and the Af phase transition temperature of the mesh rod 111 is greater than or equal to 4°C. In this embodiment, the Af phase transition temperature of the first connecting rod 211 is more than 4°C higher than the Af phase transition temperature of the mesh rod 111, which gives the first connecting rod 211 better bending performance and makes the support more flexible during retraction.

[0059] Example 2:

[0060] Figure 3 This is a schematic diagram of the structure of the bracket provided in an embodiment of the present invention. Please refer to [link / reference]. Figure 3 As shown, this embodiment provides a support, including multiple grid segments 1 and multiple connecting segments 2. The grid segment 1 includes multiple circumferentially connected grid units 11. The connecting segment 2 includes a first connecting rod 211 and a second connecting rod 212. The first connecting rod 211 and the second connecting rod 212 are both used to connect axially adjacent grid units 11. The Af phase transition temperature of the first connecting rod 211 is different from that of the second connecting rod 212.

[0061] The difference from the above embodiments is that in this embodiment, the first connecting rod in connecting segment 2 is only a part of the connecting rod, not all of it. Therefore, in this embodiment, the first connecting rod 211 can be a connecting rod with a low heat treatment temperature, or the second connecting rod 212 can be a connecting rod with a low heat treatment temperature. Correspondingly, the Af phase transition temperature of the first connecting rod 211 is different from the Af phase transition temperature of the second connecting rod 212. For example, the Af phase transition temperature of the first connecting rod 211 is greater than the Af phase transition temperature of the second connecting rod 212, or the Af phase transition temperature of the first connecting rod 211 is less than the Af phase transition temperature of the second connecting rod 212.

[0062] In this embodiment, the Af phase transition temperature of the first connecting rod 211 is different from that of the second connecting rod 212, which means that the first connecting rod 211 and the second connecting rod 212 of the connecting segment 2 have a strength difference, which provides good flexibility while giving the bracket retractable performance.

[0063] Those skilled in the art can design the ratio of the number of first connecting rods 211 to the number of second connecting rods 212 as needed. Preferably, the ratio of the number of first connecting rods 211 to the number of second connecting rods 212 in each connecting segment is greater than 1:19 and less than 19:1. For example, the ratio of the number of first connecting rods 211 to the number of second connecting rods 212 can be 1:9, 9:1, or 1:1.

[0064] Figure 3 The support shown has hexagonal grid cells, with each grid segment 1 containing 12 grid cells, and a total of 4 grid segments. Accordingly, Figure 3 The bracket shown has three connecting segments, each with 12 connecting rods. There are six first connecting rods 211 and six second connecting rods 212, and the first connecting rods 211 and the second connecting rods 212 are arranged alternately in the circumferential direction. The connecting rods in this embodiment provide sufficient radial support while exhibiting good flexibility.

[0065] Preferably, the Af phase transition temperature of the first connecting rod differs from that of the second connecting rod 212 by 4 degrees Celsius or more, so as to ensure that the first connecting rod or the second connecting rod with a higher Af phase transition temperature has better flexibility.

[0066] Example 3:

[0067] Figure 4 This is a schematic diagram of the structure of the sheath provided in an embodiment of the present invention. Figure 5 This is a schematic diagram of a support with a protective sleeve installed during heat treatment, provided as an embodiment of the present invention. Please refer to... Figure 2-5 This embodiment provides a method for manufacturing a support structure to obtain the support structure of Embodiment 1 or Embodiment 2. The manufacturing method includes:

[0068] S101. The metal pipe is made into a bare support. The bare support includes multiple grid segments 1 and multiple connecting segments 2. The grid segment 1 includes multiple grid units 11 connected in sequence in the circumferential direction. Each grid unit 11 includes multiple grid rods 111. The connecting segment 2 includes multiple connecting rods. The connecting rods are used to connect axially adjacent grid units 11.

[0069] Specifically, the metal tubing in this embodiment can be made of nickel-titanium alloy, or other biocompatible metal materials. This embodiment does not impose any particular restrictions on the specific material of the stent. This embodiment also does not impose any particular restrictions on the method for preparing the bare stent from the metal tubing; for example, laser cutting can be used.

[0070] Similar to the embodiments described above, the grid cells 11 in this embodiment are either closed or open. Optionally, the grid cells are closed polygons or circles. For example, the grid cells can be triangles, rhombuses, hexagons, or circles, etc. Alternatively, the grid cells can be open wavy, spiral, or zigzag shapes.

[0071] S102. The bare support is heat-treated, wherein at least some of the connecting rods in the connecting section are heated at a temperature lower than the mesh rods in the grid section during heat treatment, so that the Af phase transition temperature of the first connecting rod 211 is greater than the Af phase transition temperature of the mesh rod 111.

[0072] In this embodiment, at least some of the connecting rods in connecting segment 2 are heat-treated at a temperature lower than that of the mesh rods in the grid segment, resulting in the first connecting rod in the connecting segment. This differentiated heat treatment of at least some of the connecting rods ensures that the Af phase transition temperature of the first connecting rod 211 is higher than that of the mesh rods in grid segment 1 and the remaining connecting rods (if any) in connecting segment 2. Simultaneously, the first connecting rod 211 exhibits superior bending performance compared to the mesh rods in grid segment 1 and the remaining connecting rods (if any) in connecting segment 2, resulting in better flexibility of the support and facilitating its retraction.

[0073] This embodiment does not impose a particular limitation on the number of first connecting rods 211 to be prepared in each connecting segment. Exemplarily, the number of first connecting rods 211 in each connecting segment is greater than 5% of the total number of connecting rods. Preferably, the number of first connecting rods 211 is greater than 20% of the total number of connecting rods. More preferably, the number of first connecting rods 211 is greater than 50% of the total number of connecting rods. Preferably, the connecting rods in each connecting segment are subjected to differentiated heat treatment at intervals to ensure that the resulting first connecting rods 211 are evenly arranged circumferentially on the support. This allows the support to provide sufficient radial support while maintaining good flexibility.

[0074] Preferably, the connecting rods in each connecting segment undergo differentiated heat treatment so that the difference between the Af phase transition temperature of the first connecting rod and the Af phase transition temperature of the mesh rod is greater than or equal to 4°C. This results in the first connecting rod having superior bending performance, and the support exhibiting better flexibility during retraction.

[0075] Further, step S102, which involves heat-treating the bare support, includes:

[0076] A thermally insulating sheath 3 is provided, wherein the sheath 3 has a protective portion 32, the protective portion 32 has a groove 321 for receiving the connecting rod;

[0077] The sheath 3 is disposed on the connecting section 2, wherein the groove 321 of the protective part 32 accommodates the connecting rod for preparing the first connecting rod, so as to reduce the temperature of the accommodated connecting rod during the heat treatment process.

[0078] Preferably, the sheath 3 is annular to be fitted onto the bare bracket. The sheath 3 also includes a connecting portion 31 for connecting the protective portion 32, and the connecting portion 31 has a hollow structure for covering the connecting rods not accommodated in the groove 321, that is, the connecting rods on the connecting segment 2 that are not used to prepare the first connecting rod 211 (for example, these connecting rods are heat-treated to obtain the second connecting rod in Embodiment 2), so that the temperature of this part of the connecting rod is higher than the temperature of the connecting rod used to prepare the first connecting rod 211 during heat treatment. Exemplarily, such as Figure 4 , 5 As shown, the protective part 32 and the connecting part 31 are arranged at intervals and connected end to end. The hollow structure is used not only to cover the connecting rods not used to prepare the first connecting rod 211, but also to cover part of the grid rods of the grid segment.

[0079] This embodiment does not impose any particular restrictions on the preparation method and raw materials of the sheath 3. For example, the sheath 3 can be obtained by processing ceramic aluminum silicate fiber board.

[0080] In this step, the bare support covered with the thermally insulating sheath 3 is placed in a heating furnace for heating. The connecting rod protected by the protective part 32 in the sheath 3 has a lower temperature, while the bare support part not covered by the sheath 3 or covered by the hollow structure of the sheath 3 (such as the connecting rod not used to prepare the first connecting rod and the mesh rod of the mesh segment) has a higher temperature. As a result, the Af temperature of the obtained first connecting rod 211 is higher than that of other parts, and it has better bending performance and flexibility.

[0081] This embodiment does not impose any particular limitation on the specific method of heat treatment. Preferably, a single heat treatment creates a temperature difference of more than 30°C between the first connecting rod 211 and other parts, resulting in better flexibility of the first connecting rod 211. For example, the bare bracket covered with the sheath 3 is placed at a temperature of 480-520°C for 1-2 minutes, then removed and quenched, and this process is repeated 4-6 times. In this embodiment, each heat treatment is repeated multiple times, but the heating time each time is short, ensuring that the heated part of the bracket does not conduct excessive heat to the part protected by the sheath 3.

[0082] Furthermore, this embodiment also includes a step of pre-expanding the bare support. That is, the diameter of the bare support is smaller than the diameter of the support, and after the metal tubing is fabricated into a bare support, the following steps are also included:

[0083] S103. Insert a second mandrel with a diameter smaller than that of the bare support but larger than that of the bare support into the bare support to pre-expand the diameter of the bare support, then perform heat setting, and then take it out for quenching.

[0084] This embodiment does not impose any particular restrictions on the specific method of bare stent pre-expansion or the parameters of heat setting. Those skilled in the art can select a second mandrel of appropriate size according to the desired expansion size, and determine the heat setting temperature, time, and number of expansion and setting cycles.

[0085] Preferably, during heat setting, the temperature of the connecting rod 211 to be fabricated is lower than the temperature of the rest of the bare support, achieving differentiated heat setting. For details, please refer to step S102.

[0086] Furthermore, when the bare support is heat-treated, wherein at least some of the connecting rods in the connecting segment 2 are at a lower temperature during heat treatment than the mesh rods 111 in the mesh segment 1, so that the Af phase transition temperature of the first connecting rod 211 is greater than the Af phase transition temperature of the mesh rod 111, a first mandrel 4 with a diameter equivalent to that of the support is first squeezed into the bare support fitted with a sheath 3, so as to expand the bare support to the final desired support diameter.

[0087] In this embodiment, the first mandrel 4 and the second mandrel are preferably made of stainless steel.

[0088] Furthermore, this embodiment also includes a polishing step. That is, S104, the bare bracket is heat-treated, wherein at least some of the connecting rods in the connecting segment 2 are at a lower temperature during heat treatment than the mesh rods 111 in the mesh segment 1, so that the Af phase transition temperature of the first connecting rod 211 is greater than the Af phase transition temperature of the mesh rods 111, and then the bracket is polished.

[0089] This embodiment does not have particular limitations on the specific polishing method, as long as it can remove burrs from the stent and reduce surface roughness. Exemplarily, electrochemical polishing is used, with a polishing voltage of 30-60V and a polishing time of 30-60s. The stent is then removed and ultrasonically cleaned with anhydrous ethanol for 1 minute. This step results in a smooth and bright stent surface, reducing the difficulty of stent retraction caused by surface roughness and burrs, thus improving retraction performance.

[0090] If the support structure of Embodiment 2 is prepared such that only a portion of the connecting rods in the connecting segment of the support structure are the first connecting rods, this embodiment also provides an alternative manufacturing method, including:

[0091] S101' The metal pipe is made into a bare support. The bare support includes multiple grid segments and multiple connecting segments. The grid segment includes multiple grid cells connected in sequence in the circumferential direction. The connecting segment includes multiple connecting rods. The connecting rods are used to connect axially adjacent grid cells.

[0092] S102' The bare support is subjected to heat treatment, wherein during the heat treatment, the temperature of the connecting rod used to prepare the first connecting rod in the connecting section is different from the temperature of the connecting rod used to prepare the second connecting rod, so that the Af phase transition temperature of the first connecting rod is different from the Af phase transition temperature of the second connecting rod.

[0093] The more specific details are similar to the above embodiments and will not be repeated here.

[0094] The performance of the stent provided in this embodiment will be described in detail below based on comparative tests. (Refer to...) Figure 3 The support structure shown has a number of connecting rods (i.e., the first connecting rods) that require differentiated heat treatment in each connecting segment, which account for 50% of the total number of connecting rods and are arranged alternately in the circumferential direction. The support obtained by processing according to steps S101-S104 is the test sample 1.

[0095] refer to Figure 3 The bracket structure shown has a number of connecting rods (i.e., the first connecting rods) that require differentiated heat treatment, which accounts for 1 / 12 of the total number of connecting rods. The bracket obtained by processing according to steps S101-S104 is the test sample 2.

[0096] refer to Figure 3 The support structure shown requires differentiated heat treatment for each of the 12 connecting rods in each connecting segment, i.e., each of them is used as the first connecting rod. The support obtained by processing according to steps S101-S104 is the test sample 3.

[0097] refer to Figure 3 The stent structure shown is prepared by obtaining a pre-expanded bare stent according to steps S101 and S103, then performing heat treatment on the stent according to step S102, and then polishing according to step S104. The processing time and temperature of each step are the same as those of test sample 1, the difference being that the entire stent is heat treated, that is, no protective sleeve is put on the stent during heat treatment, and the final stent obtained is reference sample 1.

[0098] refer to Figure 3 The scaffold structure shown yields a bare scaffold, but the difference lies in the absence of a connecting rod at the location corresponding to the first connecting rod in test sample 1. A pre-expanded bare scaffold is obtained according to step S103, followed by heat treatment according to step S102, and then polishing according to step S104. The processing time and temperature for each step are consistent with test sample 1, the difference being that the entire scaffold is heat-treated, i.e., no protective sleeve is applied during heat treatment. The final scaffold obtained is reference sample 2. Table 1 is a summary and comparison table of the five scaffold preparation methods.

[0099]

[0100]

[0101] Table 1: Summary Comparison of Five Types of Stents

[0102] In various embodiments of the present invention, bending performance and vascular compliance are used to represent the bending performance of the first connecting rod and the flexibility of the stent.

[0103] Test method:

[0104] Stent withdrawal test:

[0105] refer to Figure 1 As shown, the proximal apex of five types of stents, namely test sample 1, test sample 2, test sample 3, reference sample 1, and reference sample 2, with a length / outer diameter of 50mm / 7mm, is first squeezed and contracted into the distal end of the sheath 5 to simulate a stent in a semi-released state. Then, the traction device 6, which enters from the proximal end of the sheath 5, is used to pull the apex of the stent that has entered the retraction sheath 5 to test whether the stent can be pulled into the sheath 5 as a whole.

[0106] Cornering performance test:

[0107] Figure 6 This is a schematic diagram illustrating the bending performance test of the bracket provided in an embodiment of the present invention. Please refer to [link / reference]. Figure 6 As shown, five types of supports (sample 1, sample 2, sample 3, reference sample 1, and reference sample 2), with length / outer diameter of 50 mm / 7 mm, were compressed into a straight section of a transparent quartz tube 7 with an inner diameter of 3.5 mm (50% of the support's outer diameter). The quartz tube 7 consists of a straight section and a curved section. The straight section is the same length as the support, while the curved section has multiple bends within a 50 mm length. A tensile testing machine was used to push the tail end of the support through the curved section of the quartz tube 7 at a speed of 100 mm / min. The peak force during the pushing process represents the support's compliance.

[0108] Vascular compliance test:

[0109] Figure 7 This is a schematic diagram illustrating the vascular compliance test process of the stent provided in an embodiment of the present invention. Please refer to [link / reference]. Figure 7 As shown, five types of stents, namely test sample 1, test sample 2, test sample 3, reference sample 1, and reference sample 2, with a length / outer diameter of 50 mm / 7 mm, were released into a simulated thin-walled silicone blood vessel 8 with a length / inner diameter of 60 mm / 7 mm (the same as the outer diameter of the stent). The simulated blood vessel 8 was sufficiently flexible. By pulling 5 mm from each end of the simulated blood vessel 8, the stent and the simulated blood vessel 8 were bent at 120°. The deformation of the stent at the middle of the simulated blood vessel 8 was recorded, and the minimum outer diameter of the stent after bending was measured.

[0110] Af phase transition temperature test method:

[0111] The Af phase transition temperature test method is referenced in the group standard T / CSBM 0017—2021 "Evaluation Method for Shape Recovery Performance of Nickel-Titanium Shape Memory Alloy Cardiac Occluders". Table 2 is a comparison table of stent withdrawal test results. Table 2: Comparison of Stent Retraction Test Results

[0112] The retraction test results show that the open-loop reference sample 2 cannot be retracted, while the differentiated heat-treated samples 1, 2, and 3, and the fully closed-loop reference sample 1 without differentiated heat treatment, can all be retracted. The peak pushing force results show that samples 1, 3, and reference sample 2 have better stent flexibility, with peak pushing forces of 1.6N, 1.2N, and 2.1N respectively. Sample 2 has a relatively higher peak pushing force due to its lower proportion of the first connecting rod. The fully closed-loop reference sample 1, without differentiated heat treatment, has a higher pushing force of 5.2N due to its poor flexibility. The vascular compliance test results show the same pattern: samples 1, 2, 3, and reference sample 2 all exhibit only slight deformation. The fully closed-loop reference sample 1, without differentiated heat treatment, collapsed due to bending during the experiment, demonstrating poor flexibility.

[0113] Therefore, the stent and its preparation method provided by the embodiments of the present invention endow the stent with excellent flexibility, which can solve the problem of traditional stents being difficult to retract.

[0114] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A support, characterized in that: The system comprises multiple grid segments and multiple connecting segments. Each grid segment includes multiple circumferentially connected grid cells, and each grid cell includes multiple grid rods. Each connecting segment includes multiple connecting rods for connecting axially adjacent grid cells. Each connecting rod includes a first connecting rod, the Af phase transition temperature of which is greater than that of the grid cell to improve the retractability of the support. In each connecting segment, the number of first connecting rods accounts for more than 50% of the total number of connecting rods. The grid cell is closed, and the grid cell can be polygonal or circular; In this configuration, two circumferentially adjacent grid cells are directly connected by sharing a single grid pole, or two circumferentially adjacent grid cells are connected by a connector.

2. The bracket according to claim 1, characterized in that: The difference between the Af phase transition temperature of the first connecting rod and the Af phase transition temperature of the net rod is greater than or equal to 4℃.

3. A support, characterized in that: The system comprises multiple grid segments and multiple connecting segments. Each grid segment includes multiple circumferentially connected grid cells. Each connecting segment includes a first connecting rod and a second connecting rod, both of which are used to connect axially adjacent grid cells. The Af phase transition temperature of the first connecting rod is greater than that of the second connecting rod to improve the retraction performance of the support. The first and second connecting rods are arranged alternately in the circumferential direction. In each connecting segment, the number of first connecting rods accounts for more than 50% of the total number of connecting rods.

4. The stent according to claim 3, characterized in that: The difference between the Af phase transition temperature of the first connecting rod and the Af phase transition temperature of the second connecting rod is greater than or equal to 4℃.

5. A method for manufacturing a stent, used to manufacture a stent according to any one of claims 1-2, characterized in that, include: The metal tubing is fabricated into a bare support, which includes multiple grid segments and multiple connecting segments. Each grid segment includes multiple grid units connected circumferentially. Each grid unit includes multiple grid rods. Each connecting segment includes multiple connecting rods, which are used to connect axially adjacent grid units. The bare support is heat-treated, wherein at least a portion of the connecting rods in the connecting segment are subjected to a lower temperature during heat treatment than the mesh rods in the mesh segment, so as to obtain a first connecting rod with an Af phase transition temperature greater than that of the mesh rod.

6. The method for manufacturing a support according to claim 5, characterized in that: The step of heat-treating the bare support, wherein at least a portion of the connecting rods in the connecting segment are at a lower temperature than the mesh rods in the mesh segment during the heat treatment, to obtain a first connecting rod with an Af phase transition temperature greater than that of the mesh rod, includes: A thermally insulating sheath is provided, wherein the sheath has a protective portion having a groove for receiving the connecting rod; The sheath is disposed on the connecting section, wherein the groove accommodates the connecting rod for preparing the first connecting rod, so as to reduce the temperature of the accommodated connecting rod during the heat treatment process.

7. The method for manufacturing a support according to claim 6, characterized in that: The sheath is ring-shaped and is fitted onto the bare support. The sheath also includes a connecting portion for connecting the protective portion, and the connecting portion has a hollow structure for covering the connecting rod not accommodated by the groove, so that the temperature of this part of the connecting rod is higher than the temperature of the connecting rod used to make the first connecting rod during heat treatment.

8. The method for manufacturing a support according to claim 6, characterized in that: The bare bracket with the sheath is heat-set at 480-520℃ for 1-2 minutes, then quenched and the process is repeated 4-6 times.

9. The method for manufacturing a support according to claim 6, characterized in that: In the step of heat-treating the bare support, wherein during the heat treatment, the temperature of at least a portion of the connecting rods in the connecting segment is lower than the temperature of the mesh rods in the mesh segment, so as to obtain a first connecting rod with an Af phase transition temperature greater than that of the mesh rods, a first mandrel with a diameter equivalent to that of the support is first squeezed into the bare support with the sheath, so as to expand the bare support to the diameter of the support.

10. The method for manufacturing a support according to any one of claims 6-8, characterized in that: During heat treatment, the temperature of the connecting rod used to prepare the first connecting rod is more than 30°C lower than the temperature of the mesh rod of the mesh segment during heat treatment.

11. The method for manufacturing a support according to claim 5, characterized in that: The diameter of the bare support is smaller than the diameter of the support. After the metal pipe is made into a bare support, the process further includes: inserting a second mandrel with a diameter smaller than the diameter of the support but larger than the diameter of the bare support into the bare support to pre-expand the diameter of the bare support, then performing heat setting, and then taking it out for quenching.

12. The method for manufacturing a support according to claim 5 or 6, characterized in that: The step of heat-treating the bare support, wherein at least a portion of the connecting rods in the connecting segment are at a lower temperature than the mesh rods in the mesh segment during the heat treatment, so as to obtain a first connecting rod with an Af phase transition temperature greater than that of the mesh rods, further includes polishing the support.

13. A method for manufacturing a stent, used to manufacture a stent according to any one of claims 3-4, characterized in that, include: The metal tubing is fabricated into a bare support, which includes multiple grid segments and multiple connecting segments. Each grid segment includes multiple circumferentially connected grid cells, and each connecting segment includes multiple connecting rods for connecting axially adjacent grid cells. The bare support is subjected to heat treatment, wherein during the heat treatment, the temperature of the connecting rod used to prepare the first connecting rod in the connecting segment is different from the temperature of the connecting rod used to prepare the second connecting rod, so that the Af phase transition temperature of the first connecting rod is different from the Af phase transition temperature of the second connecting rod.

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