WO2021135057A1 - Stent périphérique résorbable et son procédé de préparation - Google Patents

Stent périphérique résorbable et son procédé de préparation Download PDF

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WO2021135057A1
WO2021135057A1 PCT/CN2020/092502 CN2020092502W WO2021135057A1 WO 2021135057 A1 WO2021135057 A1 WO 2021135057A1 CN 2020092502 W CN2020092502 W CN 2020092502W WO 2021135057 A1 WO2021135057 A1 WO 2021135057A1
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stent
region
absorbable
content
end region
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PCT/CN2020/092502
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English (en)
Chinese (zh)
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温焘源
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元心科技(深圳)有限公司
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/82—Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/86—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure
    • A61F2/90—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure
    • A61F2/91—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes
    • A61F2/915—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes with bands having a meander structure, adjacent bands being connected to each other
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L31/00—Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
    • A61L31/02—Inorganic materials
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L31/00—Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
    • A61L31/02—Inorganic materials
    • A61L31/022—Metals or alloys
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L31/00—Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
    • A61L31/14—Materials characterised by their function or physical properties, e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L31/00—Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
    • A61L31/14—Materials characterised by their function or physical properties, e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
    • A61L31/148—Materials at least partially resorbable by the body
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2240/00—Manufacturing or designing of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
    • A61F2240/001—Designing or manufacturing processes

Definitions

  • the present invention relates to the field of medical devices, in particular to an absorbable peripheral stent and a preparation method thereof.
  • lower extremity arteriosclerosis With the aging of the population and changes in diet, the incidence of lower extremity arteriosclerosis has increased year by year, and severe patients even have lower extremity arteriosclerosis occlusion. The prevalence of the disease in patients over 60 years old in our country can reach 20%, which seriously affects the quality of life of the elderly and even threatens their lives.
  • the lower extremity arterial stent implantation is one of the powerful weapons in the treatment of lower extremity arteriosclerosis, which can effectively open blood vessels, relieve lower extremity pain, difficulty walking and other ischemic symptoms.
  • the basic method of endovascular interventional treatment of lower extremity arteries is: percutaneous puncture to establish a treatment pathway, guide wire catheter to establish a working track through the lesion, balloon expansion to open the diseased blood vessel, vascular stent in the corresponding position, and finally complete the reconstruction of the occluded blood vessel.
  • Vascular stents can be divided into balloon-expandable stents and self-expanding stents according to the release method.
  • the balloon-expandable stent metal tube is laser-engraved and is inherently inelastic. Its design is to pre-install the stent on the balloon and deliver the stent to the vascular lesion through the balloon catheter. After the balloon expands to the intended diameter, it depends on the blood vessel. The wall retraction force adheres to the blood vessel wall and does not produce continuous expansion tension on the blood vessel wall.
  • the balloon-expandable stent has good compliance, strong ability to pass through lesions, and strong support, but it is easily deformed by external forces. Especially when the stent is placed in a peripheral blood vessel, the peripheral blood vessel is wrapped by nearby muscles, and the blood vessel is relatively rugged, and the vascular stent is subject to complex external forces and is more prone to deformation.
  • Permanent stents in blood vessels can cause a series of adverse reactions, such as neointimal hyperplasia, stent thrombosis, and mid-stage restenosis.
  • Absorbable stents can solve this problem well. It can mechanically support the blood vessel wall, release anti-stenosis drugs within a set time, and can promote the recovery of vasomotor function, and produce a physiological response to stress and exercise without the risk of inflammation, thrombosis and accelerated arteriosclerosis. For peripheral arterial disease, absorbable stents are the future trend.
  • the absorbable material at this stage is a ball-expanded stent, which is susceptible to external forces.
  • the material is degraded or corroded, and the support strength of the stent is reduced. At this time, when external force acts, it is more likely to deform.
  • the blood vessel is relatively flexible, and the stent is a rigid body, when the stent is expanded in the blood vessel, where the mechanical properties of the two are different, there is a sudden change in the mechanical properties of the end portion, and the stress is the largest.
  • the blood vessels are stretched or compressed by external force, under the action of external force, the stent is more prone to local excessive stress and even local deformation.
  • the same metal round tube is generally used to engrave patterns on the metal round tube by means of laser cutting or etching to form a bracket.
  • the prior art generally uses a completely symmetrical stent pattern, that is, the stent pattern at the end part is the same as the stent pattern at the middle part. According to the above description, the stresses on the end portion and the middle portion are inconsistent, and the bracket of the prior art is prone to end deformation.
  • One method is to use a special pattern design to change the stent pattern design at the end into a pattern design that can provide higher radial strength to solve the problem of stent flattening.
  • the number of bracket rods in the same ring at the end can be increased, or the width of the bracket rods at the end can be increased.
  • the end of the bracket is indeed strengthened, and the problem of inconsistency in force between the end and the middle part can be solved.
  • a new problem has been introduced.
  • the existing technology can easily cause the expansion speed of the two ends to be different from that of the middle, resulting in uneven expansion of the stent, thereby increasing the risk of stent fracture and restenosis at the lesion;
  • Another method is to increase the thickness of the end bracket rod to solve this problem.
  • a new problem is also introduced. Because the thickness of the two ends is different from the thickness of the middle part, there is a risk that the stent rod will easily scratch the blood vessel wall during expansion.
  • Another method is to use strengthening the overall material strength of the stent to solve this problem, such as increasing the hardness of the overall material of the stent.
  • high hardness means sacrificing the plasticity of the material, which in turn causes the flexibility of the prepared stent to increase with the material.
  • the hardness increases and decreases. This means that the stent as a whole is less likely to pass through the curved blood vessel, resulting in the failure of the product to reach the lesion position smoothly.
  • absorbable stents In addition to the stent prone to deformation at both ends, absorbable stents also have other specialties. Generally, the same material is used for the material of the absorbable stent, and its mechanical properties and corrosion properties are basically the same. In animal experiments, it is found that the first corroded stent rods generally appear randomly. Because the overall material of the absorbable stent is the same, it means that the intrinsic corrosion rate of all stent rod materials is the same. The local microenvironment (such as the slightly acid environment) of the stent rod that determines the more corrosion rate of the stent rod and the residual stress of the stent rod Caused by stress corrosion.
  • the local microenvironment such as the slightly acid environment
  • the local microenvironment is mainly related to the local physiological environment of the patient, while the residual stress of the stent rod is mainly related to the stent manufacturing process and the expansion process. These two data appear randomly and are related to the doctor's operation and the patient's own condition. . Moreover, these two data are beyond the control of the current human medical level, so the prior art cannot directionally corrode some stent rods preferentially.
  • the first stent rod to corrode appears randomly. It is easy to cause the corrosion rate of local stent rods to be too fast, and some stent rods have not yet started corrosion. In extreme cases, if the stent rod is significantly collapsed or broken in half in the middle, the stent rod that does not initiate corrosion may cause perforation of the blood vessel wall, which is extremely risky to the patient.
  • the present invention provides an absorbable peripheral stent, which includes two end regions and a middle region arranged between the two end regions, and the material composition of the end regions is different from the material composition of the middle region , So that the material strength of the end region is greater than the material strength of the intermediate region, and the corrosion rate of the end region is greater than the corrosion rate of the intermediate region.
  • the nitrogen content and/or carbon content of the end region is higher than the nitrogen content and/or carbon content of the middle region.
  • the difference between the nitrogen content in the end region and the nitrogen content in the middle region is not less than 500 ppm; or
  • the difference between the carbon content in the end region and the carbon content in the middle region is not less than 500 ppm; or
  • the difference between the total content of nitrogen and carbon in the end region and the total content of nitrogen and carbon in the middle region is not less than 500 ppm.
  • the nitrogen content and/or carbon content of the intermediate region changes in a gradient from a position close to the intermediate region to a position far away from the intermediate region.
  • the Vickers hardness of the end region is not less than 300 HV, and the Vickers hardness of the middle region is not less than 200 HV.
  • the in vitro immersion corrosion rate of the end region is 0.25 to 2.5 times greater than the in vitro immersion corrosion rate of the middle region.
  • the length of each of the end regions is 1 to 3 mm.
  • a method for preparing an absorbable peripheral stent includes providing an absorbable stent preform, and performing nitriding, carburizing, or carbonitriding treatment on the two end regions of the absorbable stent preform to make the post-treatment
  • the material composition of the end region and the middle region of the absorbable stent preform is different, and the material strength of the end region is greater than the material strength of the middle region, and the corrosion rate of the end region is greater than The corrosion rate in the middle area is high.
  • the absorbable stent preform before nitriding, carburizing, or carbonitriding the two end regions of the absorbable stent preform, it further includes performing the middle region of the absorbable iron-based stent Block.
  • the two end regions of the absorbable stent preform are subjected to nitriding, carburizing, or carbonitriding treatment until the nitrogen content of the end regions is equal to the total nitrogen content in the end regions.
  • the difference in the nitrogen content in the intermediate zone is not less than 500 ppm; or
  • the difference between the carbon content in the end region and the carbon content in the middle region is not less than 500 ppm; or
  • the difference between the total content of nitrogen and carbon in the end region and the total content of nitrogen and carbon in the middle region is not less than 500 ppm.
  • the above absorbable outer peripheral stent by changing the material composition of the end region and the middle region, can make the material strength of the end region greater than the material strength of the middle region, and the corrosion rate of the end region is greater than the corrosion rate of the middle region.
  • the probability of deformation of the absorbable peripheral stent can be reduced, and the corrosion rate of the end area can be increased, so that the absorbable peripheral stent will begin to corrode from the end area, reducing the stent rod in the middle area from puncturing the vessel wall and causing the vessel wall. Risk of perforation.
  • Fig. 1 is a schematic structural diagram of an absorbable peripheral stent according to an embodiment of the application
  • FIG. 2 is a schematic diagram of a structure in which the middle area of the absorbable peripheral stent is blocked according to an embodiment of the application.
  • the prior art generally uses design schemes of modifying the stent, such as pattern structure and increasing the rod width.
  • changes in the design may easily bring about other influences, such as uneven expansion of the stent.
  • This application considers to solve the problem of easy deformation at both ends of the peripheral stent without changing the design of the stent.
  • the present application provides an absorbable peripheral stent 10, which includes two end regions 100 and an intermediate region 200 disposed between the two end regions.
  • the material composition of the end region 100 is different from the material composition of the middle region 200, so that the material strength of the end region 100 is greater than the material strength of the middle region 200, and the corrosion rate of the end region 100 is greater than the corrosion rate of the middle region 200 .
  • the length of each end region is 1 to 3 mm.
  • the above absorbable outer peripheral stent by changing the material composition of the end region and the middle region, can make the material strength of the end region greater than the material strength of the middle region, and the corrosion rate of the end region is greater than the corrosion rate of the middle region.
  • the probability of deformation of the absorbable peripheral stent can be reduced, and the corrosion rate of the end area can be increased, so that the absorbable peripheral stent will corrode from the end area, and reduce the stent rod caused by the first corrosion in the middle area and then the fracture. Risk of vascular perforation.
  • the stent pattern of the end region 100 of the absorbable outer peripheral stent 10 and the stent pattern of the middle region 200 of the present application are basically the same (the number of stent rods in the circumferential direction is the same, and the width and wall thickness of the stent rods are the same).
  • the nitrogen content and/or carbon content of the end region 100 is higher than that of the middle region 200.
  • the nitrogen content and/or carbon content of the end region 100 is higher than that of the middle region 200.
  • the metal and nitrogen/carbon inside the metal unit cell in the end region respectively form fine and dispersed metal nitride/metal carbide second phase particles, and the second phase inside the crystal grains The phase particles can hinder the movement, entanglement, and pinning of dislocations, thereby increasing the radial strength and toughness of the end region.
  • the absorbable outer peripheral stent is obtained by using pure iron as a raw material by performing nitriding, carburizing or carbonitriding treatment on the end area.
  • the end region can be treated by ion or gas nitriding, carburizing, and carbonitriding.
  • the difference between the nitrogen content of the end regions 100 and the nitrogen content of the middle region 200 is not less than 500 ppm; or The difference between the carbon content of the region 100 and the carbon content of the middle region 200 is not less than 500 ppm; or the difference between the total nitrogen and carbon content of the end region 100 and the total nitrogen and carbon content of the middle region 200 is not less than 500ppm; it can make the end area 100 have a strong radial support force to support the more complex stress conditions in the end area, and make the corrosion rate of the end area 100 greater than the corrosion rate of the middle area 200, so that the outer periphery can be absorbed
  • the stent 10 corrodes from the end region in the body, reducing the risk of blood vessel perforation caused by the stent rod that corrodes first and then breaks in the middle region.
  • the content of nitrogen/the content of carbon is an average concentration.
  • the content of nitrogen in the end region is an average concentration.
  • the content of nitrogen in the end region is an average concentration.
  • the nitrogen content, or carbon content, or total nitrogen and carbon content of the end region 100 is not more than 2000 ppm.
  • the nitrogen content/carbon content reaches a certain concentration, the second phase particles in the unit cell will cover the entire unit cell interface, and the newly added nitrogen/carbon will be more difficult to hinder the movement of more dislocations.
  • the enhancement effect (such as radial strength and toughness, etc.) is small.
  • the wall thickness of the absorbable peripheral stent is generally on the order of micrometers, when the nitrogen content, or carbon content, or the total content of nitrogen and carbon in the end region reaches 2000 ppm, the strengthening effect on the material approaches Maximum value.
  • the strengthening effect on the material is not significantly improved, but it can still increase the corrosion rate of the material.
  • the nitrogen content, or carbon content, or total nitrogen and carbon content of the end region may exceed 2000 ppm.
  • the nitrogen content/carbon content of the middle region 200 changes gradually from a position close to the end region 200 to a position far from the end region, that is, the middle region gradually changes from both ends to the middle. Decrease can avoid sudden changes in concentration from the end area to the middle area, and improve the overall performance of the absorbable peripheral stent.
  • the Vickers hardness of the end region 100 is not less than 300 HV, and the Vickers hardness of the middle region 200 is not less than 200 HV, so as to ensure that the end region 100 can cope with complex stress conditions.
  • the Vickers hardness test method is as follows: the stent is inlaid into a metallographic sample, and the value measured by keeping it under a test force of 0.05 kgf for 10 seconds is the Vickers hardness value.
  • the in vitro immersion corrosion rate of the end region 100 is 0.25 to 2.5 times greater than the in vitro immersion corrosion rate of the middle region 200. That is, the in vitro immersion corrosion rate of the end region 100 is 1.25 to 3.5 times the in vitro immersion corrosion rate of the intermediate region 200, which can make the absorbable outer peripheral stent corrode from the end region in vivo, and reduce the corrosion caused by the first corrosion and then the fracture of the middle region. Risk of vascular perforation caused by the stent rod.
  • the present application also provides a method for preparing an absorbable peripheral stent, which includes providing an absorbable stent preform, and nitriding, carburizing, or carbonitriding the two end regions of the absorbable stent preform to make
  • the material composition of the end region and the middle region of the treated absorbable stent preform is different, and the material strength of the end region is greater than the material strength of the middle region, and the corrosion rate of the end region is greater than the corrosion rate of the middle region .
  • the absorbable preform is laser-cut through a round tube of pure iron (iron content> 99.96% by weight), and the stent pattern in the end area is basically the same as the stent pattern in the middle area.
  • the number of the upper support rods is the same, and the width and wall thickness of the support rods are basically the same).
  • the end area can be treated by ion or gas nitriding, carburizing, and carbonitriding.
  • it before nitriding, carburizing, or carbonitriding the two end regions of the absorbable stent preform, it further includes blocking the middle region of the absorbable iron-based stent.
  • FIG. 2 please refer to FIG. 2.
  • a metal ring 40 is provided on the outer surface of the middle area of the absorbable preform 30 to block. The metal ring 40 can block the plasma nitrogen element from interfering with the middle area.
  • the area is bombarded, and the end area penetrates into the stent rod under the bombardment of plasma nitrogen element, so that the nitrogen content of the end area is higher than the nitrogen content of the middle area.
  • the middle area will also be bombarded by slight nitrogen elements, so the middle area will also have a certain amount of nitrogen.
  • the wall thickness of the metal ring is gradient. Specifically, the wall thickness from the two ends to the middle gradually increases.
  • the middle area is close to the end area, and the metal ring
  • the gap is gradually reduced from the position near the end area in the middle area to the position far away from the end area, so that when nitriding, carburizing or carbonitriding is performed .
  • the nitrogen content and/or carbon content in the middle area decreases gradually from the position of the middle area near the end area to the position of the middle area away from the end area, that is, the middle area is from From the ends to the middle, the nitrogen content and/or carbon content gradually decrease, which can avoid sudden changes in positions and improve the overall performance of the absorbable peripheral stent.
  • the two end regions of the absorbable stent preform are subjected to nitriding, carburizing, or carbonitriding treatment until the nitrogen content in the end region is equal to the nitrogen content in the middle region.
  • the difference is not less than 500 ppm; or the difference between the carbon content in the end region and the carbon content in the middle region is not less than 500 ppm; or the total content of nitrogen and carbon in the end region and the total content of nitrogen and carbon in the middle region are not less than 500 ppm.
  • the difference is not less than 500ppm, which can make the end area have a strong radial support force to support the more complicated stress conditions in the end area, and make the corrosion rate of the end area greater than the corrosion rate of the middle area, making it absorbable
  • the peripheral stent corrodes in the body from the end area, reducing the risk of vascular perforation caused by the stent rod that corrodes first and then breaks in the middle area.
  • the stent can be placed under an IT100 scanning electron microscope of JEOL Co., Ltd. for energy spectrum analysis test.
  • the nitrogen content of the stent was measured. Because the nitrogen content was too low, it was found that the low-concentration nitrogen content could not be identified through the energy spectrum analysis test under the scanning electron microscope.
  • the nitrogen content of this part can be tested using ONH2000 model oxygen, nitrogen and hydrogen analyzer of German ELTRA company.
  • the in vitro immersion corrosion test is as follows:
  • a round tube of pure iron (iron content> 99.96% by weight) with a wall thickness of about 100 ⁇ m is laser-cut to cut into a symmetrical pattern stent.
  • the outer surface of the support is smooth, forming a preform.
  • the preform is ion nitriding, and the outer surface of the middle area is blocked with a metal ring, and the two end regions are exposed for ion nitriding.
  • the duration of ion nitriding is 120 minutes.
  • the stent was polished and then expanded to the nominal diameter with a balloon catheter, and then the properties were measured.
  • the nitrogen content of the stent rod at the end area was measured to be 2000ppm, the Vickers hardness was 357HV, and the in vitro immersion corrosion rate was about 2.0mm/y.
  • the nitrogen content of the stent rod in the middle region is 500ppm, the hardness is 252HV, and the corrosion rate in vitro is about 0.7mm/y.
  • a round tube of pure iron (iron content> 99.96% by weight) with a wall thickness of about 100 ⁇ m is laser-cut to cut into a symmetrical pattern stent.
  • the outer surface of the support is smooth, forming a preform.
  • the preform is ion carburized, and the outer surface of the middle area is blocked by a metal ring, and the two end regions are exposed for ion carburizing.
  • the duration of ion carburizing is 80 minutes.
  • the carburized stent was polished and then expanded to a nominal diameter with a balloon catheter, and then the properties were measured.
  • the carbon content of the stent rod in the end region was measured to be 1100ppm, the Vickers hardness was 305HV, and the in vitro immersion corrosion rate was about 0.9mm/y.
  • the carbon content of the stent rod in the middle area is 500ppm, the Vickers hardness is 219HV, and the in vitro immersion corrosion rate is about 0.6mm/y.
  • a round tube of pure iron (iron content> 99.96% by weight) with a wall thickness of about 100 ⁇ m is laser-cut to cut into a symmetrical pattern stent.
  • the outer surface of the support is smooth, forming a preform.
  • the preform is gas nitriding, the inner and outer surfaces of the middle area are blocked by metal rings, and the two end areas are exposed for gas nitriding.
  • the gas nitriding time is 180 minutes.
  • the stent was polished and then expanded to the nominal diameter with a balloon catheter, and then the properties were measured.
  • the nitrogen content of the stent rod in the end area was measured to be 2600ppm, the hardness was 368HV, and the in vitro immersion corrosion rate was about 2.4mm/y.
  • the nitrogen content of the stent rod in the middle area is 700ppm, the hardness is 265HV, and the corrosion rate in vitro is about 0.7mm/y.
  • a round tube of pure iron (iron content> 99.96% by weight) with a wall thickness of about 100 ⁇ m is laser-cut to cut into a symmetrical pattern stent.
  • the outer surface of the support is smooth, forming a preform.
  • the preform is gas carburized, and the inner and outer surfaces of the middle area are blocked by metal rings, and the two end regions are exposed for gas carburizing.
  • the gas carburizing time is 100 minutes.
  • the carburized stent was polished and then expanded to a nominal diameter with a balloon catheter, and then the properties were measured.
  • the carbon content of the stent rod in the end region was measured to be 1500ppm, the Vickers hardness was 310HV, and the in vitro immersion corrosion rate was about 1.2mm/y.
  • the carbon content of the stent rod in the middle area is 400ppm, the Vickers hardness is 215HV, and the in vitro immersion corrosion rate is about 0.6mm/y.
  • a round tube of pure iron (iron content> 99.96% by weight) with a wall thickness of about 100 ⁇ m is laser-cut to cut into a symmetrical pattern stent.
  • the outer surface of the support is smooth, forming a preform.
  • Gas carbonitriding is used for the preform, a metal ring is used to block the outer surface of the middle area, and the two end regions are exposed for gas carbonitriding.
  • the duration of gas carbonitriding is 80 minutes.
  • the carburized stents were polished and then expanded to a nominal diameter with a balloon catheter, and then their properties were measured.
  • the total carbon and nitrogen content of the stent rod in the end region was measured to be 1600ppm, the hardness was 338HV, and the in vitro immersion corrosion rate was about 1.4mm/y.
  • the total carbon and nitrogen content of the stent rod in the middle area is 700ppm, the hardness is 243HV, and the in vitro immersion corrosion rate is about 0.6mm/y.

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Abstract

Sont divulgués un stent périphérique absorbable (10) et son procédé de préparation. Le stent périphérique résorbable (10) comprend deux régions d'extrémité (100) et une région centrale (200) qui est disposée entre les deux régions d'extrémité (100), la composition de matériau des régions d'extrémité (100) étant différente de celle de la région centrale (200), de telle sorte que la résistance de matériau des régions d'extrémité (100) est supérieure à celle de la région centrale (200), et le taux de corrosion des régions d'extrémité (100) est supérieur à celui de la région centrale (200). En ce qui concerne le stent périphérique résorbable (10), sans introduire d'autres problèmes, la probabilité de déformation du stent résorbable (10) peut être réduite, et le taux de corrosion des régions d'extrémité (100) peut être augmenté, de telle sorte que la corrosion du stent périphérique résorbable (10) commence à partir des régions d'extrémité (100), et le risque de perforation vasculaire provoquée par la corrosion des tiges de stent puis leur fracture dans la région centrale (200) est réduit.
PCT/CN2020/092502 2019-12-31 2020-05-27 Stent périphérique résorbable et son procédé de préparation WO2021135057A1 (fr)

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WO2000064375A1 (fr) * 1999-04-22 2000-11-02 Advanced Cardiovascular Systems, Inc. Stents radio-opaques
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