Self-expanding woven stent, preparation method and application

Abstract

The invention relates to a self-expanding woven stent, a preparation method and application. The self-expansion type woven stent is of a tubular net-shaped structure formed by weaving metal wires in a crossed mode, and the self-expansion type woven stent has the characteristics that the axial size is shortened when the radial size is increased, and the axial size is prolonged when the radial size is reduced; the radial compression amount of the self-expanding woven stent is defined as X, and the ratio of the axial dimension extension amount divided by the nominal length of the stent is defined as the stent extension rate Y; within the radial compression range of 0%-20%, the extension rate Y of the stent and the radial compression amount X are in a linear relation Y = aX, and a is smaller than 1; the surface of the metal wire is provided with a nanoscale oxide layer. According to the self-expanding woven stent with the linear relation between the elongation rate and the radial compression amount, the axial length of the implanted stent can be predicted through the linear relation under the condition that the inner diameter of a blood vessel is known, and more accurate placement positioning and stent type selection basis are provided for an operator.

Description

Technical Field

[0001] The present invention belongs to the technical field of medical device implants, and in particular relates to a self-expanding braided stent, a preparation method and use thereof. Background Art

[0002] Vascular interventional therapy refers to the operation technique of introducing specific medical consumables into the lesion site through the blood vessels under the guidance of medical imaging equipment for minimally invasive treatment. According to the different treatment sites, vascular interventional devices can be divided into cardiovascular interventional devices (coronary artery, aorta), cerebrovascular interventional devices, and peripheral vascular interventional devices.

[0003] Aneurysms formed by dilation or expansion of the arterial wall due to arterial lesions or damage are a common vascular disease. The use of woven stents or covered stents with a certain weaving density to guide blood flow reconstruction can block the flow of blood into the aneurysm, reduce the blood supply in the aneurysm, and the aneurysm will gradually shrink to a safe level.

[0004] In addition, due to aortic disease or damage, the aortic blood breaks through the intima and flows into the aortic wall media, separating the intima from the media, and the blood in the lumen flows between the two, causing the wall to be divided into two true and false cavities. Blood can flow between the true and false cavities or form thrombi; and once the integrity of the wall is destroyed, only one layer of outer membrane remains on the original wall. Under the impact of high-pressure blood flow in the lumen, the wall is easily broken, causing artery rupture and causing rapid death of the patient. The implantation of a woven stent with a certain density guides the reconstruction of blood flow, blocks the blood flow into the aortic dissection, reduces the blood supply in the aortic dissection, and gradually returns the aortic dissection to a safe level.

[0005] Braided stents are usually made of warp and weft threads interwoven into a coherent mesh structure, with weaving points formed where the warp and weft threads interweave. The nominal diameter and nominal length of a braided stent are the diameter and length at the diameter when it is expected to be used. However, in actual use, the implantation environment usually does not completely match the nominal diameter, especially when the distal end of the blood vessel is thinner and the proximal end is thicker. Selecting the proximal diameter of the blood vessel as the nominal diameter often results in the actual diameter of the stent after implantation being smaller than the nominal diameter, making the actual length of use greater than the nominal length. This difference affects the operator's prediction of the implantation position and the stability of the stent, increasing the risk of surgery.

[0006] Therefore, there is a need in the art to develop a self-expanding braided stent that can accurately predict the diameter and length of the stent during use and provide a reference for the operator. Summary of the invention

[0007] In view of the shortcomings of the prior art, one of the purposes of the present invention is to provide a self-expanding braided stent, wherein the braided stent is formed by cross-weaving metal wires to form a tubular mesh structure, and the self-expanding braided stent has the characteristics that the axial dimension is shortened when the radial dimension increases, and the axial dimension is extended when the radial dimension decreases; the radial compression amount of the self-expanding braided stent is defined as X, and the ratio of the axial dimension extension amount divided by the nominal length of the stent is defined as the stent extension rate Y;

[0008] In the range of 0%-20% radial compression of the self-expanding braided stent, the stent elongation rate Y and the radial compression amount X are in a linear relationship Y=aX, a<1; the surface of the metal wire has a nano-scale oxide layer.

[0009] The radial compression of the self-expandable braided stent of 0% means that the self-expandable braided stent is in a state of its nominal diameter.

[0010] The elongation rate of the self-expanding braided stent is linearly related to the radial compression amount, which makes it possible to predict the actual axial length of the stent under the premise of knowing the radial size of the stent. This feature provides the operator with a more accurate basis for stent placement and stent selection. Specifically, during the implantation process, an imaging device is used to locate a section of healthy blood vessels near the lesion (such as the aneurysm diameter or blood vessel rupture) and measure the inner diameter of the section of blood vessels. Based on the linear relationship, the expected length of the stent at this radial size can be calculated, so as to select a self-expanding braided stent that can cover the lesion and adapt to changes in vascular contraction and relaxation. This method helps ensure that the stent can be stably anchored in the blood vessel, thereby improving the success rate and safety of the implantation.

[0011] Typically, the tubular mesh structure is formed by weaving a number of warps and wefts together to form a coherent mesh structure, wherein the warps and wefts are interwoven to form weaving points, wherein the weaving points include positive weaving points and negative weaving points, wherein the weaving points where the warps are located above the wefts are positive weaving points, and the weaving points where the warps are located below the wefts are negative weaving points.

[0012] Preferably, the thickness of the nanoscale oxide layer on the surface of the metal wire is ≤100 nm, preferably 1-10 nm, such as 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, etc., and more preferably 1-8 nm.

[0013] Preferably, the diameter of the metal wire is in the range of 0.001 to 0.25 mm, for example, 0.002 mm, 0.009 mm, 0.01 mm, 0.03 mm, 0.05 mm, 0.07 mm, 0.09 mm, 0.11 mm, 0.13 mm, 0.15 mm, 0.18 mm, 0.20 mm, 0.22 mm, 0.24 mm, etc.

[0014] The commonly used stent braiding materials in the art can be used in the present application. As an optional specific implementation, the metal wire material is any one of cobalt-based alloy, chromium-based alloy, nickel-based alloy, titanium-based alloy, iridium alloy, platinum alloy, tungsten alloy, and tantalum alloy; preferably, the metal wire is cobalt-chromium alloy wire.

[0015] The metal wires provided in the present application may also contain a small amount of alloy wires with radiopaque development properties, such as any one of platinum-tungsten alloy wires, platinum-tungsten-tantalum alloys, and platinum alloy wires, or a combination of at least two thereof.

[0016] The nano-scale oxide layer described in the present application is an oxide layer with a nano-scale thickness. The composition of the nano-scale oxide layer is a material formed after the stent braiding material is heated and oxidized, and is not limited thereto.

[0017] In the prior art, after the braided wire is woven into a tubular mesh structure, it is heat-set to achieve a predetermined radial size, and an oxide layer is formed on the surface of the metal wire. The oxide layer structure formed by direct oxidation is usually relatively loose. During the deformation process of the stent from a compressed state to an expanded state, changes in the angle and / or position of the intersection will cause friction between the braided wires, which will cause part of the loose oxide layer to fall off, forming an uneven surface. This uneven surface will affect the deformation law of the stent, resulting in irregular changes in radial compression and axial elongation, making it impossible for the operator to accurately predict the radial size and release position of the stent, increasing the complexity and risk of the surgical operation.

[0018] The surface of the metal braided wire with a nano-scale oxide layer is relatively smooth and has low friction, thereby reducing the contact resistance between the metal wires. This feature helps the stent maintain a more uniform deformation during the stress process, thereby optimizing its linear deformation. The smooth surface of the metal wire also effectively reduces the phenomenon of local stress concentration, thereby reducing the nonlinear deformation caused by local friction, so that the radial compression X of the self-expanding braided stent and the stent elongation rate Y show a strong linear relationship.

[0019] The formation process of the nanoscale oxide layer is not specifically limited in this application. For example, the nanoscale oxide layer can be directly formed by a specific oxidation process (such as slow oxidation under a lower oxygen partial pressure), and / or the oxide layer can be processed into a nanoscale oxide layer by processes such as corrosion, passivation and / or plasma treatment after direct oxidation.

[0020] It oxidizes slowly under a lower oxygen partial pressure, and the oxidation rate is slow, and the formed nanoscale oxide layer is thin and dense.

[0021] The oxide layer formed by direct oxidation has an inner layer that is denser than the outer layer. After processes such as corrosion, passivation and / or plasma treatment, the nanoscale oxide layer formed is also a thin and dense oxide layer.

[0022] In a preferred embodiment, the metal wire is a cobalt-chromium alloy wire, and the nano-scale oxide layer is a chromium oxide layer, which is usually also a thin and dense passivation film.

[0023] The present application does not specifically limit the braiding method of the self-expanding braided stent. Any braiding method of the self-expanding braided stent that can be obtained by a person skilled in the art can be used in the present application. Typically but not limitedly, any of the following braiding methods can be included:

[0024] One-up-one-down weaving method: a warp thread is adjacent to the positive weaving point and the reverse weaving point formed by the weft thread crossing the warp thread, and a weft thread is adjacent to the positive weaving point and the reverse weaving point formed by the warp thread crossing the weft thread;

[0025] Two-up and two-down weaving method: a warp thread and four adjacent weft threads crossing the warp thread form a weave thread, and the weave thread includes four weaving points, namely two positive weaving points and two reverse weaving points, wherein the two positive weaving points are adjacent or the two reverse weaving points are adjacent;

[0026] Double-strand composite weaving method: every two warps form a warp group, every two wefts form a weft group, the spacing between the two warps in the warp group is spacing one, the spacing between the two wefts in the weft group is spacing two, the spacing between two adjacent warp groups is spacing three, the distance of spacing three is greater than the distance between spacing one and spacing two; and / or the spacing between two adjacent weft groups is spacing four, the distance of spacing four is greater than the distance between spacing one and spacing two;

[0027] Three-strand composite weaving method: every three warps form a warp group, every three wefts form a weft group, the three warps in one warp group are tightly stacked, and the three wefts in one weft group are tightly stacked; preferably, the three warps in one warp group are spirally wound, and / or the three wefts in one weft group are spirally wound.

[0028] In the one-up-one-down weaving method, the two-up-two-down weaving method, and the double-strand composite weaving method, the tubular network structure formed by the weaving of the warp and weft threads forms a single-layer structure with warp and weft threads staggered up and down regularly or irregularly on the radial two-dimensional plane structure, which is usually used for neurovascular stents. In the three-strand composite weaving method, the tubular network structure formed by the weaving of the warp and weft threads forms a multi-layer structure with warp and weft threads staggered up and down regularly or irregularly on the radial two-dimensional plane structure, which is usually used for aortic stents or peripheral vascular stents.

[0029] Preferably, the braiding angle is 120-160°, exemplified by 125°, 128°, 135°, 140°, 146°, 153°, 158°, etc.

[0030] In the braiding angle range of 120-160°, the braided wires of the braided stent are interwoven to form a more reasonable mechanical structure. This range enables the stent to exhibit a more uniform deformation during radial compression, while reducing the friction during expansion, making the deformation of the stent more controllable during expansion, thereby further making the radial compression X of the self-expanding braided stent and the stent elongation rate Y show a strong linear relationship.

[0031] As a preferred technical solution, the surface of the metal wire meets the following properties:

[0032] After the metal wires are woven into a tubular stent with a PPI of 125 to 160, the water contact angle thereof is 50 to 90 degrees.

[0033] It should be noted that the above properties define the surface characteristics of the metal wire. By weaving a tubular stent with a specific PPI, the contact angle of the surface of the woven tubular stent is measured to define the hydrophilicity of the metal wire surface. The metal wire surface of the braided stent usually has an oxide layer, which makes the surface hydrophilic. On this basis, the surface roughness has a significant effect on hydrophilicity: the higher the surface roughness, the stronger the hydrophilicity; and the smoother the surface, the weaker the hydrophilicity, and the contact angle increases accordingly. Smoother surfaces usually show lower hydrophilicity, that is, larger contact angles, indicating less frictional resistance. This smooth surface property reduces the friction during the release of the stent, making the interaction between the metal wires more uniform and the deformation of the stent more regular, thereby ensuring a more stable linear relationship between the radial compression X and the stent elongation rate Y of the self-expanding braided stent.

[0034] It should be noted that, in the above performance, "weaving the metal wires into a tubular stent with a PPI of 125 to 160" is only a preparatory step for measuring the contact angle and does not limit the structure of the self-expanding braided stent.

[0035] Preferably, the value range of a is 0.3-0.7, such as 0.4, 0.5, 0.6, etc.

[0036] The self-expanding braided stent provided in the present application can be applied to any blood vessel in the body, exemplarily including any one or at least two of the neural blood vessels, the aorta or the peripheral blood vessels.

[0037] Generally, nerves and blood vessels are thinner, and the radial dimension changes during contraction and relaxation of blood vessels are small. The self-expanding braided stent used for nerves and blood vessels will select a relatively small braiding diameter and a relatively thinner metal wire. Therefore, as an optional specific embodiment, the nominal diameter of the self-expanding braided stent is preferably 2.7mm to 5.8mm, such as 3.0mm, 3.2mm, 3.5mm, 3.8mm, 4.0mm, 4.3mm, 4.6mm, 4.9mm, 5.2mm, 5.5mm, 5.7mm, etc. The nominal length of the self-expanding braided stent is preferably 15 to 60mm, such as 16mm, 18mm, 25mm, 30mm, 34mm, 38mm, 40mm, 45mm, 49mm, 50mm, 53mm, 58mm, etc. The diameter range of the metal wire is preferably 0.001 to 0.1mm. The value range of a is preferably 0.4 to 0.6. The water contact angle of the self-expanding braided stent is preferably 50-75°.

[0038] For the aorta or peripheral blood vessels, the radial dimension of the blood vessels is larger, and the radial dimension changes greatly during the contraction and relaxation of the blood vessels. The self-expanding braided stent used will choose a relatively large braiding diameter, and thicker metal wires can be used. Therefore, as an optional specific embodiment, the nominal diameter of the self-expanding braided stent is preferably 20 to 60 mm; the nominal length of the self-expanding braided stent is preferably 8 to 20 cm; the diameter range of the metal wire is preferably 0.1 to 0.25 mm; the value range of a is preferably 0.3 to 0.6; the water contact angle of the self-expanding braided stent is preferably 70 to 90°.

[0039] Those skilled in the art can prepare the self-expanding braided stent described in this application based on the background knowledge they have mastered, and any known method or new method that can obtain the self-expanding braided stent described in this application can be used in this application. This application provides the following preferred preparation method.

[0040] The second object of the present application is to provide a method for preparing a self-expanding braided stent as described in the first object, comprising the following steps:

[0041] (1) Weaving metal wires into a tubular mesh structure;

[0042] (2) subjecting the tubular mesh structure to a heat setting treatment so that it reaches a predetermined radial dimension and forms an oxide layer on the surface of the metal wire;

[0043] (3) performing corrosion treatment on the tubular mesh structure after heat setting to remove part of the oxide layer;

[0044] (4) passivating the treated tubular network structure to form a passivation oxide layer;

[0045] Preferably, after step (3) and / or step (4), the tubular network structure after the oxide layer is removed is subjected to low-temperature plasma treatment.

[0046] The heat setting treatment will form a thick and loose oxide layer on the surface of the tubular mesh structure. The loose oxide layer can be removed by corrosion treatment, which can clean the surface of the metal wire and create conditions for subsequent passivation. The passivation treatment forms a thin and dense passivation film on the surface of the metal wire. Before the passivation treatment, the stent is treated with low-temperature plasma. By introducing high-energy ion bombardment and active seeds, the surface can be further cleaned, the hydrophilicity of the surface can be enhanced, and the full contact of the passivation liquid can be promoted, making the passivation reaction more uniform, which helps to form a dense passivation film. After the passivation treatment, the stent is treated with low-temperature plasma, which can further optimize the surface structure of the passivation layer, effectively remove microscopic surface defects, and enhance the uniformity and density of the passivation film, thereby reducing the friction between the braided wires of the stent and improving the surface uniformity, so that the self-expanding braided stent exhibits more stable deformation characteristics during radial compression and axial extension, and improves implantation accuracy and reliability.

[0047] Generally, the heat setting is to weave a metal wire into a metal mesh tube with an axial length along its outer circumference with a core shaft as the axis, and then heat up, so that the metal mesh is heat-set into a shape that matches the diameter of the core shaft to obtain a self-expanding tubular stent. During the transportation process, the self-expanding tubular stent is restrained by external forces, the radial size is reduced, and the axial size is extended; during the implantation process, as the restraining external force of the self-expanding tubular implant is removed, the radial size automatically expands, and the axial adaptability is shortened.

[0048] Preferably, the heat setting temperature is 600-700° C., and the temperature fluctuation during the heat setting process is less than or equal to 5° C.; the heat treatment time is 10-20 min.

[0049] Preferably, the plasma gas of the low-temperature plasma treatment is selected from any one of nitrogen, hydrogen or argon, or a combination of at least two of them; the pressure of the low-temperature plasma treatment is preferably between 50 and 100 Pa; the temperature of the low-temperature plasma treatment is preferably between room temperature and 60°C; and the time of the low-temperature plasma treatment is 5 to 15 minutes.

[0050] The present application does not specifically limit the corrosion treatment, and any corrosion treatment that can remove the loose oxide layer can be used in the present application.

[0051] Typically but not limitatively, the corrosion treatment comprises immersing the heat-set pipe network structure in an acid agent, wherein the acid agent comprises an acid, exemplarily such as hydrochloric acid and / or hydrobromic acid; the acid agent may also comprise a corrosion inhibitor and / or a surfactant in addition to the acid, wherein the corrosion inhibitor is selected from acetylene alcohols, such as propynol, butynol, methylpentynol and / or 1,4-butynediol; the surfactant is selected from sodium dodecyl sulfate and / or o-benzoylsulfonimide.

[0052] The corrosion treatment may also include soaking in an acid agent for more than two times, and may also include soaking in an alkaline agent between soakings in different acid agents. The alkaline agent includes solution A and solution B, wherein solution A contains sodium permanganate and / or potassium permanganate, and solution B contains sodium hydroxide and / or potassium hydroxide.

[0053] The present application does not make any specific limitation on the passivation treatment, and any passivation treatment that can form a dense oxide layer can be used in the present application.

[0054] Preferably, the passivation treatment includes immersing the corroded pipe network structure in a passivation solution, which contains 20 to 50 vol.% nitric acid; optionally, the passivation solution is a 30 to 45 vol.% nitric acid solution; the passivation time is 20 to 60 minutes, optionally the time is 20 to 55 minutes; the passivation temperature is 20 to 70°C, optionally, the temperature is 25 to 50°C.

[0055] The third object of the present application is to provide a vascular implant system, comprising:

[0056] The self-expanding braided stent as described in the first object, or the self-expanding braided stent obtained by the method described in the second object, and

[0057] The delivery system is used to deliver the self-expanding braided stent to a target location and release it.

[0058] Compared with the prior art, this application has the following beneficial effects:

[0059] The present application provides a self-expanding braided stent in which the elongation rate is linearly related to the radial compression amount. Through the linear relationship, the axial length of the stent after implantation can be accurately predicted under the condition of known inner diameter of the blood vessel, providing the operator with more accurate placement positioning and stent selection basis, thereby improving surgical accuracy, reducing implantation deviation, and further improving treatment effect and surgical safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 A transmission electron microscopy image of the metal wire cross section of a self-expanding braided stent is shown, with a scale of 50 nm.

[0061] Figure 2A schematic diagram of the self-expandable braided stent being compressed by a corresponding amount from the nominal diameter is given, where X is the radial compression amount, B is the nominal length, and b is the length change of the self-expandable braided stent after being compressed by the radial compression amount X. DETAILED DESCRIPTION

[0062] The technical solution of the present invention is further explained below in conjunction with specific implementation methods. However, it should be noted that the specific implementation methods are only a specific implementation and explanation of the essence of the technical solution of the present invention, and should not be understood as a limitation on the protection scope of the present invention.

[0063] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It should also be noted that, for ease of description, only the parts related to the relevant invention are shown in the accompanying drawings.

[0064] The following examples and comparative examples of cobalt-chromium alloy wire are used as examples for illustration. After testing, the proportions of the cobalt-nickel-chromium alloy are as follows:

[0065] 35.2wt% nickel, 20.5wt% chromium and 10.1wt% molybdenum, ≤1wt% iron, ≤1wt% titanium, ≤0.15wt% manganese, ≤0.15wt% silicon, ≤0.025wt% carbon, ≤0.015wt% phosphorus, ≤0.015wt% sulfur and the balance cobalt.

[0066] Example 1

[0067] A method for preparing a self-expanding braided stent, comprising:

[0068] (1) On the mandrel, cobalt-chromium alloy wires (circular in cross section and 0.03 mm in diameter) are woven into a metal mesh tube with an outer diameter of 5.8 mm and a length of 30 mm in a two-up and two-down manner;

[0069] (2) heating the metal mesh tube to 650° C. in an atmospheric atmosphere, and then heat treating it within a temperature range of 650±5° C. for 15 min to perform heat setting treatment, so that the metal mesh tube is set at a size of about 5.8 mm in outer diameter, and an oxide layer is formed on the outer surface of the cobalt-chromium alloy wire, thereby obtaining a heat-set braided stent;

[0070] (3) The heat-set braided stent is placed in an acidic etching solution and immersed for 40 minutes for corrosion, wherein the acidic etching solution includes 13wt% hydrochloric acid, 0.12wt% sodium dodecyl sulfate, 0.3wt% 1,4-butynediol, and the remainder is water; after etching, the braided stent is cleaned and dried to remove moisture, thereby obtaining a corroded braided stent.

[0071] (4) The braided stent after the corrosion treatment is subjected to plasma treatment in an argon (Ar) atmosphere with a treatment time of 10 min and a treatment temperature of 30° C. to obtain a braided stent after the plasma treatment.

[0072] (5) The plasma-treated braided stent was placed in a passivation solution (containing 30 vol.% nitric acid solution), the passivation temperature was controlled at 50°C, and the passivation was performed for 50 minutes to obtain a passivated braided stent. The water contact angle was measured to be 75°.

[0073] The braided stent after the passivation treatment is a self-expanding braided stent.

[0074] The self-expanding braided stent obtained in Example 1 has a nominal diameter of 5.6 mm and a length of 30 mm.

[0075] The metal wire cross-section of the self-expanding braided stent was scanned and observed using a transmission electron microscope (model JEM ARM300F spherical aberration corrected transmission electron microscope). Figure 1 shown. Figure 1 The transmission electron micrograph of the cross section of the metal wire of the self-expanding braided stent is given, with a scale of 50 nm. Figure 1 It can be seen that the metal wire surface of the self-expanding braided stent has an oxide layer with a thickness of about 2 nm. Combined with the energy spectrum, it can be determined that the oxide layer is a chromium oxide layer.

[0076] Figure 2 A schematic diagram of the self-expandable braided stent being compressed by a corresponding amount from the nominal diameter is given, where X is the radial compression amount, B is the nominal length, and b is the length change of the self-expandable braided stent after being compressed by the radial compression amount X.

[0077] Example 2

[0078] The only difference from Example 1 is that step (1) is:

[0079] On the mandrel, cobalt-chromium alloy wires (circular in cross section and 0.03 mm in diameter) were woven into a metal mesh tube with an outer diameter of 3.8 mm and a length of 30 mm in a two-up and two-down manner. The water contact angle was measured to be 73°.

[0080] The self-expanding braided stent obtained in Example 2 has a nominal diameter of 3.5 mm and a length of 30 mm, and the surface of the metal wire has an oxide layer with a thickness of about 2 nm.

[0081] Example 3

[0082] The only difference from Example 1 is that steps (3) to (5) are:

[0083] (3) The heat-set braided stent is placed in an acidic etching solution and immersed for 30 minutes for corrosion, wherein the acidic etching solution includes 13wt% hydrochloric acid, 0.12wt% sodium dodecyl sulfate, 0.3wt% 1,4-butynediol, and the remainder is water; after etching, the braided stent is cleaned and dried to remove moisture, thereby obtaining a corroded braided stent.

[0084] (4) The braided stent after the corrosion treatment is subjected to plasma treatment in an argon (Ar) atmosphere with a treatment time of 10 min and a treatment temperature of 30° C. to obtain a braided stent after the plasma treatment.

[0085] (5) The plasma-treated braided stent was placed in a passivation solution (containing 30 vol.% nitric acid solution), the passivation temperature was controlled at 50°C, and the passivation was performed for 50 minutes to obtain a passivated braided stent. The water contact angle was measured to be 73°.

[0086] The self-expanding braided stent obtained in Example 3 has a nominal diameter of 5.6 mm and a length of 30 mm, and the surface of the metal wire has an oxide layer with a thickness of about 8 nm.

[0087] Example 4

[0088] The only difference from Example 1 is that steps (3) to (5) are:

[0089] (3) The heat-set braided stent is placed in an acidic etching solution and immersed for 25 minutes for corrosion, wherein the acidic etching solution includes 13wt% hydrochloric acid, 0.12wt% sodium dodecyl sulfate, 0.3wt% 1,4-butynediol, and the remainder is water; after etching, the braided stent is cleaned and dried to remove moisture, thereby obtaining a corroded braided stent.

[0090] (4) The braided stent after the corrosion treatment is subjected to plasma treatment in an argon (Ar) atmosphere for 8 minutes at a treatment temperature of 30° C. to obtain a plasma-treated braided stent.

[0091] (5) The plasma-treated braided stent was placed in a passivation solution (containing 30 vol.% nitric acid solution), the passivation temperature was controlled at 50°C, and the passivation was performed for 50 minutes to obtain a passivated braided stent. The water contact angle was measured to be 71°.

[0092] The self-expanding braided stent obtained in Example 4 has a nominal diameter of 5.6 mm and a length of 30 mm, and the surface of the metal wire has an oxide layer with a thickness of about 10 nm.

[0093] Example 5

[0094] The only difference from Example 1 is that steps (3) to (5) are:

[0095] (3) The heat-set braided stent is placed in an acidic etching solution and immersed for 20 minutes for corrosion, wherein the acidic etching solution includes 11wt% hydrochloric acid, 0.12wt% sodium dodecyl sulfate, 0.3wt% 1,4-butynediol, and the remainder is water; after etching, the braided stent is cleaned and dried to remove moisture, thereby obtaining a corroded braided stent.

[0096] (4) The braided stent after the corrosion treatment is subjected to plasma treatment in an argon (Ar) atmosphere with a treatment time of 5 min and a treatment temperature of 30° C. to obtain a braided stent after the plasma treatment.

[0097] (5) The plasma-treated braided stent was placed in a passivation solution (containing 30 vol.% nitric acid solution), the passivation temperature was controlled at 50°C, and the passivation was performed for 50 minutes to obtain a passivated braided stent. The water contact angle was measured to be 65°.

[0098] The self-expanding braided stent obtained in Example 5 has a nominal diameter of 5.6 mm and a length of 30 mm, and the surface of the metal wire has an oxide layer of about 50 nm thick.

[0099] Example 6

[0100] A method for preparing a self-expanding braided stent, comprising:

[0101] (1) On a core shaft, a cobalt-chromium alloy wire (circular in cross section and 0.25 mm in diameter) is woven into a metal mesh tube with an outer diameter of 41 mm and a length of 100 mm in a three-strand composite manner;

[0102] (2) heating the metal mesh tube to 650° C. in an atmospheric atmosphere, and then heat treating it within a temperature range of 650±5° C. for 35 min to perform heat setting treatment, so that the metal mesh is set at a size of about 40 mm in outer diameter, and an oxide layer is formed on the outer surface of the cobalt-chromium alloy wire, thereby obtaining a heat-set braided stent;

[0103] (3) The heat-set braided stent is placed in an acidic etching solution and immersed for 40 minutes for corrosion, wherein the acidic etching solution includes 13wt% hydrochloric acid, 0.12wt% sodium dodecyl sulfate, 0.3wt% 1,4-butynediol, and the remainder is water; after etching, the braided stent is cleaned and dried to remove moisture, thereby obtaining a corroded braided stent.

[0104] (4) The braided stent after the corrosion treatment is subjected to plasma treatment in an argon (Ar) atmosphere with a treatment time of 10 min and a treatment temperature of 30° C. to obtain a braided stent after the plasma treatment.

[0105] (5) The plasma-treated braided stent was placed in a passivation solution (containing 30 vol.% nitric acid solution), the passivation temperature was controlled at 50°C, and the passivation was performed for 50 minutes to obtain a passivated braided stent. The water contact angle was measured to be 85°.

[0106] The braided stent after the passivation treatment is a self-expanding braided stent.

[0107] The self-expanding braided stent obtained in Example 6 has a nominal diameter of 40 mm and a length of 100 mm, and the surface of the metal wire has an oxide layer with a thickness of about 2 nm.

[0108] Comparative Example 1

[0109] The only difference from Example 1 is that step (3) to step (5) are not performed, and the heat-set braided stent is directly obtained. The water contact angle is measured to be 55°, and the metal wire surface has an oxide layer of about 200 nm thick.

[0110] Performance Test:

[0111] The self-expanding braided stent is compressed from the nominal diameter by corresponding amounts, recorded as radial compression X (respectively 0.3 mm, 0.6 mm, 0.9 mm, 1.2 mm), and the length change b of the self-expanding braided stent is recorded, and the length change b is divided by the nominal length B of the self-expanding braided stent, recorded as the stent extension rate Y; the radial compression X and the stent extension rate Y are subjected to a linear function regression to obtain a regression function Y=aX, and the correlation coefficient R is recorded 2 , R 2 The closer it is to 1, the more obvious the linear relationship between the radial compression X and the stent elongation rate Y is.

[0112] The results are shown in Table 1:

[0113] Table 1

[0114]

[0115] It can be seen from Table 1 that the radial compression X and the stent elongation Y of the self-expanding braided stent provided by the present application show an obvious linear relationship within the range of radial compression of 0% to 20%, and the correlation coefficient is relatively high, at more than 90%.

[0116] When selecting a stent using the self-expanding braided stent provided in the present application, the proximal diameter, distal diameter and ideal stent coverage length of the blood vessel where the lesion is located are measured using the standard vascular measurement method. The selected stent diameter is then confirmed based on the lesion condition. The stent length is then determined based on the radial compression of the stent, the stent elongation rate, and the ideal coverage length to ensure that the stent can effectively cover the lesion area.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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 self-expanding braided stent, characterized in that: The braided stent is formed by cross-weaving metal wires to form a tubular mesh structure. The self-expanding braided stent has the characteristics that the axial dimension is shortened when the radial dimension increases, and the axial dimension is extended when the radial dimension decreases; the radial compression amount of the self-expanding braided stent is defined as X, and the ratio of the axial dimension extension amount divided by the nominal length of the stent is defined as the stent extension rate Y; In the range of radial compression of the self-expanding braided stent of 0% to 20%, the stent elongation rate Y and the radial compression amount X are in a linear relationship of Y=aX, a<1; and the surface of the metal wire has a nano-scale oxide layer.

2. The self-expanding braided stent according to claim 1, characterized in that: The thickness of the nanoscale oxide layer on the surface of the metal wire is ≤100 nm, preferably 1 to 10 nm, and more preferably 1 to 8 nm; Preferably, the diameter of the metal wire is in the range of 0.001 to 0.25 mm.

3. The self-expanding braided stent according to claim 1 or 2, characterized in that: The metal wire is made of any one of cobalt-based alloy, chromium-based alloy, nickel-based alloy, titanium-based alloy, iridium alloy, platinum alloy, tungsten alloy and tantalum alloy, preferably cobalt-chromium alloy wire.

4. The self-expanding braided stent according to any one of claims 1 to 3, characterized in that: The braiding method of the self-expanding braided stent includes any one of a one-up-one-down braiding method, a two-up-two-down braiding method, a double-strand composite braiding method, and a three-strand composite braiding method; Preferably, the braiding angle of the self-expanding braided stent is 120-160°.

5. The self-expanding braided stent according to any one of claims 1 to 4, characterized in that: The value range of a is 0.3 to 0.

7.

6. The self-expanding braided stent according to any one of claims 1 to 5, characterized in that: The nominal diameter of the self-expanding braided stent is 2.7 to 5.8 mm; Preferably, the nominal length of the self-expanding braided stent is 15 to 60 mm; Preferably, the diameter of the metal wire ranges from 0.001 to 0.1 mm; Preferably, the value range of a is 0.4 to 0.

6.

7. The self-expanding braided stent according to any one of claims 1 to 5, characterized in that: The nominal diameter of the self-expanding braided stent is 20 to 60 mm; Preferably, the self-expanding braided stent has a nominal length of 8 to 20 cm; Preferably, the diameter of the metal wire ranges from 0.1 to 0.25 mm; Preferably, the value range of a is 0.3 to 0.

6.

8. A method for preparing a self-expanding braided stent according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: (1) Weaving metal wires into a tubular mesh structure; (2) subjecting the tubular mesh structure to a heat setting treatment so that it reaches a predetermined radial dimension and forms an oxide layer on the surface of the metal wire; (3) performing corrosion treatment on the tubular mesh structure after heat setting to remove part of the oxide layer; (4) passivating the treated tubular network structure to form a passivation oxide layer; Preferably, after step (3) and / or step (4), the tubular network structure after the oxide layer is removed is subjected to low-temperature plasma treatment.

9. The preparation method according to claim 8, characterized in that: The heat setting temperature is 600-700° C., and the temperature fluctuation during the heat setting process is less than or equal to 5° C.; the heat treatment time is 10-20 minutes.

10. A vascular implant system, characterized in that: The vascular implant system comprises: The self-expanding braided stent according to any one of claims 1 to 7, or the self-expanding braided stent obtained by the method according to claim 8 or 9, and The delivery system is used to deliver the self-expanding braided stent to a target location and release it.

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