WO2020134920A1 - 覆膜支架及其制备方法 - Google Patents

覆膜支架及其制备方法 Download PDF

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Publication number
WO2020134920A1
WO2020134920A1 PCT/CN2019/122953 CN2019122953W WO2020134920A1 WO 2020134920 A1 WO2020134920 A1 WO 2020134920A1 CN 2019122953 W CN2019122953 W CN 2019122953W WO 2020134920 A1 WO2020134920 A1 WO 2020134920A1
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WO
WIPO (PCT)
Prior art keywords
stent
layer
outer layer
stent graft
layer coating
Prior art date
Application number
PCT/CN2019/122953
Other languages
English (en)
French (fr)
Inventor
王逸斐
肖本好
Original Assignee
深圳市先健畅通医疗有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from CN201811626170.5A external-priority patent/CN109700568B/zh
Priority claimed from CN201811628529.2A external-priority patent/CN109700570B/zh
Priority claimed from CN201811626200.2A external-priority patent/CN109700569B/zh
Application filed by 深圳市先健畅通医疗有限公司 filed Critical 深圳市先健畅通医疗有限公司
Priority to EP19904495.9A priority Critical patent/EP3903730B1/en
Priority to US17/418,665 priority patent/US20220257364A1/en
Publication of WO2020134920A1 publication Critical patent/WO2020134920A1/zh

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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
    • A61F2/02—Prostheses implantable into the body
    • A61F2/04—Hollow or tubular parts of organs, e.g. bladders, tracheae, bronchi or bile ducts
    • A61F2/06—Blood vessels
    • A61F2/07—Stent-grafts
    • 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
    • A61F2/852—Two or more distinct overlapping stents
    • 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
    • A61F2210/00—Particular material properties of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
    • A61F2210/0076—Particular material properties of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof multilayered, e.g. laminated structures
    • 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
    • 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
    • A61F2250/00—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
    • A61F2250/0014—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof having different values of a given property or geometrical feature, e.g. mechanical property or material property, at different locations within the same prosthesis
    • A61F2250/0018—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof having different values of a given property or geometrical feature, e.g. mechanical property or material property, at different locations within the same prosthesis differing in elasticity, stiffness or compressibility
    • 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
    • A61F2250/00—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
    • A61F2250/0014—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof having different values of a given property or geometrical feature, e.g. mechanical property or material property, at different locations within the same prosthesis
    • A61F2250/0036—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof having different values of a given property or geometrical feature, e.g. mechanical property or material property, at different locations within the same prosthesis differing in thickness
    • 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
    • A61F2250/00—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
    • A61F2250/0014—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof having different values of a given property or geometrical feature, e.g. mechanical property or material property, at different locations within the same prosthesis
    • A61F2250/0039—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof having different values of a given property or geometrical feature, e.g. mechanical property or material property, at different locations within the same prosthesis differing in diameter

Definitions

  • the invention relates to the field of medical devices, in particular to a stent graft and a preparation method thereof.
  • the existing film-covered stent is generally composed of a metal stent and a leak-proof film
  • the film-covered material may be plastic, polyester, or polyester.
  • the plastic may be polytetrafluoroethylene (PTFE)
  • the polyester may be polyethylene terephthalate (PET) or polyurethane (PU).
  • PET and PTFE are the two most commonly used materials.
  • the PET film is generally fixed on the metal bracket by hand stitching, and the PTFE film has the characteristics of high elongation and easy deformation, and it will melt and adhere to each other at high temperatures.
  • the object of the present invention is to provide a stent graft and a preparation method thereof.
  • a stent graft including:
  • a radially compressible inner-layer stent includes an inner-layer supporting skeleton and an inner-layer covering film arranged on the inner-layer supporting skeleton;
  • a method for preparing a stent graft includes:
  • Heat conductive material is wrapped on the surface of the inner layer support and the surface of the outer layer support, wherein the thickness of the heat conductive material wrapped on the surface of the inner layer support is greater than the heat conductive material wrapped on the surface of the outer layer support;
  • the light transmittance of the outer film is greater than that of the inner film, the light transmittance of the inner film is lower, and the microscopic fiber structure of the inner film will be more complete, making the inner
  • the biocompatibility of the layer coating is better, and the cells are more likely to climb after implantation.
  • the inner layer stent can also have good elasticity, which helps the inner layer stent to achieve bending deformation, improve the flexibility and sticking of the inner layer stent Wall property, and the outer layer coating has a higher light transmittance, which can make the outer layer coating smoother than the inner layer stent.
  • a stent graft including:
  • a radially compressible inner-layer stent includes an inner-layer supporting skeleton and an inner-layer covering film arranged on the inner-layer supporting skeleton;
  • the straightening force of the inner stent (that is, the force to recover from the bent state to the natural state) is small, which can reduce the stimulation of the inner stent on the lumen wall.
  • the inner membrane will be relatively soft, which can help the inner stent to conform to the tortuous blood vessel shape; at the same time, the inner membrane has less resilience, which can make the inner membrane more deformable in the lumen.
  • the inner stent When the inner stent is implanted in the lesion, the inner stent will be expanded and expanded to a certain extent under the blood flow punching, which will help the inner stent better adhere to the wall and prevent blood from the inner layer
  • the outer side of the stent flows into the lesion location.
  • the outer layer of the stent has greater resilience. When the stent graft is released, the outer membrane can quickly rebound, which helps the outer stent to fill the inner stent and the lumen better. The gap in the wall can effectively prevent internal leakage.
  • a stent graft including:
  • the tensile strength of the outer membrane of the outer stent is greater than the tensile strength of the inner membrane of the inner stent to prevent the outer membrane from breaking during loading or release, reducing
  • the risk of failure of the stent graft, and the tensile strength of the inner layer of the membrane is small, that is, under the same conditions, under the tensile force less than the tensile strength, the deformation of the inner layer of the membrane will be larger, you can The inner layer of the membrane can better conform to the shape of the curved blood vessel.
  • the elongation of the outer layer of the membrane By setting the elongation of the outer layer of the membrane to be less than the elongation of the inner layer of the membrane, the elongation of the inner layer of the membrane is greater, which can make the inner layer of membrane under the action of blood pressure after the stent is released Proper deformation and expansion allow the inner stent to better fit the vessel wall and reduce the probability of endoleaks, while the lower elongation of the outer membrane makes the outer membrane less deformable during loading and release.
  • FIG. 1 is a schematic structural diagram of a stent graft according to an embodiment of the present application.
  • FIG. 2 is a schematic structural view of the stent graft shown in FIG. 1 and the main body stent after being implanted into a blood vessel;
  • FIG. 3 is a schematic diagram of the stent graft shown in FIG. 1 during the preparation process
  • FIG. 4 is a schematic structural diagram of a stent graft according to another embodiment of the present application.
  • FIG. 5 is a schematic structural view of the stent graft shown in FIG. 4 and the main body stent after being implanted into a blood vessel;
  • FIG. 6 is a schematic structural view of the inner stent shown in FIG. 4 from a natural state to a bent state;
  • FIG. 7 is a schematic diagram of the structure of the inner layer coating or the outer layer coating in the test process
  • FIG. 8 is a schematic diagram of the stent graft shown in FIG. 4 during the preparation process
  • FIG. 9 is a schematic structural diagram of a stent graft according to another embodiment of the present application.
  • FIG. 10 is a schematic structural view of the stent graft shown in FIG. 9 and the main body stent after being implanted into a blood vessel;
  • FIG. 11 is a schematic structural view of the stent graft shown in FIG. 9 after being loaded into a sheath tube;
  • FIG. 12 is a schematic diagram of the stent graft shown in FIG. 9 during the preparation process.
  • a blood vessel is taken as an example to illustrate the lumen.
  • the blood vessel may be an aortic arch, a thoracic aorta, or an abdominal aorta.
  • Those of ordinary skill in the art should be aware that the use of blood vessels for illustration is only an example, not a limitation of the present invention.
  • the solution of the present invention is applicable to various human lumens, such as the digestive tract lumen, etc., based on the teachings of the present invention. Such improvements and modifications are within the scope of the present invention.
  • the orientation can be defined according to the blood flow direction, and in the present invention, the blood flow is defined to flow from the proximal end to the distal end.
  • the stent graft 10 of the present invention includes an inner stent 100 and an outer stent 200.
  • the outer stent 200 is sleeved on the inner stent 100.
  • the outer stent 200 covers at least a portion of the inner stent 100 and the outer layer.
  • One end of the bracket 200 is hermetically connected to the inner bracket 100.
  • both the inner stent 100 and the outer stent 200 have radial compression capability, which can be compressed under the action of external force and self-expand or recover to its original shape by mechanical expansion (such as balloon inflation) after the external force is withdrawn. And maintain the original shape, so that after implanting the lumen, it can be fixed in the lumen by its radial support force against the lumen wall.
  • the inner stent 100 is a lumen structure with two ends open and closed in the middle. After being implanted into the lumen, the inner stent 100 can be used as a new fluid channel, for example, a new blood channel after being implanted in a blood vessel.
  • One end of the outer layer stent 200 is hermetically connected to the outer peripheral surface of the inner layer stent 100 to form a closed orifice, and the other end is open. After the outer layer stent 200 is released, it can be automatically deployed to fill the gap between the inner layer stent 100 and the lumen wall.
  • the stent graft 10 can be used for the reconstruction of branch blood vessels in the chimney technology. Please refer to FIG. 2 together, which is a schematic structural diagram of the stent graft 10 as a branch stent and a main body stent 20. After implantation, the proximal opening of the stent graft 10 and the main body stent 20 are oriented in the same direction and are arranged side by side in the main blood vessel 30.
  • the proximal end surface of the outer stent 200 of the stent graft 10 can be at least the same as the proximal end surface of the main body stent 20.
  • the proximal end surface of the inner stent 100 protrudes from the main body stent 20, the distal end of the inner stent 100 is inserted into the branch vessel for anchoring, and blood flow can enter the branch vessel through the pipeline built by the inner stent 100, So as to reconstruct the branch blood vessels.
  • the proximal regions of the stent graft 10 and the main body stent 20 are radially compressed against each other in the main blood vessel 30, and the outer stent 200 can conform to the morphology of the blood vessel wall and the main body stent 20, thus A cavity is formed between the layered stent 200 and the inner layer stent 100, and the blood flowing into the cavity can be used as a filling material to block the type I endoleak channel to prevent blood flow from entering the tumor or interlayer, while ensuring the smoothness of the inner layer stent 100. Blood can flow smoothly into branch blood vessels. It should be understood that the stent graft 10 can be used not only in conjunction with the main body stent 20 but also alone.
  • the outer layer bracket 200 includes a tapered section 201 and a straight pipe section 202 connected to the tapered section 201.
  • the end of the tapered section 201 away from the straight pipe section 202 is connected to the inner layer bracket 100.
  • One end of the tapered section 201 is hermetically connected to the inner layer stent 100, and the other end radiates outward in the direction of the distal end pointing to the proximal end to form an approximately conical structure.
  • the straight pipe section 202 is connected to the proximal end of the tapered section 201 and is connected to the inner layer
  • the brackets 100 are arranged in parallel.
  • the diameter of the straight pipe section 202 is not less than 1.5 times the diameter of the inner stent 100, which can make the outer stent better adhere to the lumen wall and simultaneously conform to the deformation of the external force, better Prevent type I endoleak. In an embodiment, the diameter of the straight pipe section 202 is not less than twice the diameter of the inner stent 100.
  • the inner-layer support includes an inner-layer support frame 110 and an inner-layer coating film 120 disposed on the inner-layer support frame 110.
  • the inner-layer support framework 110 and the inner-layer film 120 cooperate to form the side of the inner-layer support 100 wall.
  • the outer layer support 200 includes an outer layer supporting skeleton 210 and an outer layer covering film 220 disposed on the outer layer supporting skeleton 210.
  • the radial support force of the outer support skeleton 210 is less than the radial support force of the inner support skeleton 100.
  • the outer support 200 Due to the low radial support force of the outer support frame 210, the outer support 200 easily conforms to the deformation of the inner wall of the lumen, thereby avoiding the formation of a gap between the outer support 200 and the inner wall of the lumen, and better avoiding type I endoleaks, and the inner layer
  • the radial support force of the support frame 110 is large, and the inner stent 100 can be closely attached to the lumen wall to fix the entire stent graft 10 in the lumen to avoid displacement or detachment from the lumen.
  • Both the inner support frame 110 and the outer support frame 210 can be made of various biocompatible materials, including known materials used in the manufacture of implanted medical devices or a combination of various materials, such as 316L stainless steel, cobalt-chromium -Nickel-molybdenum-iron alloy, nickel-titanium alloy (Nitinol), or other biocompatible metals. Both the inner support frame 110 and the outer support frame 210 may be woven from metal wires or formed by cutting metal tubes.
  • both the inner support frame 110 and the outer support frame 210 may include a multi-turn braided wave-shaped ring in the axial direction, such as a multi-turn Z-wave; or include a spiral wound structure; or include a wire braid
  • the mesh structure may also be a cut mesh structure formed by cutting a metal tube.
  • a person of ordinary skill in the art may select a suitable inner layer support structure 110 and an outer layer support structure according to needs, which will not be repeated here.
  • both the inner support frame 110 and the outer support frame 210 are formed by braiding nickel-titanium wires.
  • the nickel-titanium wire used for the outer support frame 210 has a smaller wire diameter than the nickel-titanium wire used for the inner support frame 110. The wire diameter is helpful to reduce the sheath size required by the stent graft 10.
  • Both the outer layer coating 220 and the inner layer coating 120 are made of PTFE film.
  • the inner layer coating 120 wraps the inner support frame 110 by hot melting, and the outer layer coating 220 wraps the outer support frame 210 by hot melting. Wrapped, the outer layer coating film 200 is hermetically connected to the outer surface of the inner layer coating film 120 by hot melting.
  • the light transmittance of the outer layer coating film 220 is greater than the light transmittance of the inner layer coating film 120.
  • the light transmittance is related to the microscopic characteristics of the coating material. Taking PTFE as an example, the raw material of PTFE membrane has lower light transmittance. The lower the light transmittance of the finished coating material after processing, the closer its surface characteristics will be to the raw material, that is, the more complete the micro-fiber structure, then the coating The finished product is softer, more deformable, and has a certain viscosity. With the strengthening of process conditions (such as increasing the heating time, etc.), the surface fiber structure of the coating material merges, and the light transmittance of the finished coating material will further increase.
  • the hardness of the finished film will be higher and smoother, and it cannot be stretched at the same time.
  • the light transmittance of the outer layer coating 220 is lower, and the microscopic fiber structure of the inner layer coating 120 will be relatively complete, making the inner layer
  • the membrane 120 has better biocompatibility, and the cells are more likely to climb after implantation.
  • the inner stent 120 can also have good elasticity, which helps the inner stent 100 to achieve bending deformation and improve the flexibility of the inner stent 100 And the adhesion, and the outer layer 220 has a higher light transmittance, which can make the outer layer 220 smoother than the inner bracket 210.
  • the outer layer 220 is less likely to occur between Bonding to each other is helpful to reduce the release resistance of the stent graft 10, and the outer membrane 220 is easier to restore to the original size after release, and the gap with the lumen wall is blocked.
  • the outer-layer coating 220 and the inner-layer coating 120 may not be limited to PTFE membranes, and may also be other materials with similar properties to PTFE.
  • the light transmittance is the ratio of the luminous flux transmitted through the object to the luminous flux irradiated to the object, that is, when the intensity I 0 of the incident light is constant, the greater the intensity I a of the medium absorbs the light, the intensity of the transmitted light.
  • the light transmittance in this application can be tested using a spectrophotometer.
  • the light transmittance of the inner layer film 120 is less than 50%, and the light transmittance of the outer layer film 220 is 50% to 70%, which can help the inner layer stent 100 to better conform to the tortuous
  • the anatomical shape of the blood vessel guarantees the smoothness of the stent graft 10 in the long term.
  • the outer membrane 220 has a smooth surface, which can reduce the release resistance of the stent graft 10, and the outer membrane 220 can be easily deployed after release, which can effectively prevent endoleaks happened.
  • the thickness of the outer-layer coating 220 is smaller than the thickness of the inner-layer coating 120, which can reduce the size of the sheath required for the stent-graft 10.
  • the thickness of the outer layer coating 220 is 10 ⁇ m to 50 ⁇ m
  • the thickness of the inner layer coating 120 is 20 ⁇ m to 70 ⁇ m.
  • the light transmittance of the inner layer coating 120 is 30% to 48%
  • the thickness is 20 ⁇ m to 30 ⁇ m
  • the light transmittance of the outer layer coating 220 is 60% to 70%
  • the present application also provides a method for preparing the stent graft 10, including:
  • the layer support skeleton 110 is on the inner and outer surfaces, and the inner layer support skeleton 110 is sleeved on the mold 40 at the same time.
  • the mold 40 may be a fixing device of glass or metal material.
  • the surface of the inner bracket 100 and the surface of the outer bracket 200 are coated with the thermally conductive material 50.
  • the thickness of the thermally conductive material 50 wrapped on the surface of the inner bracket 100 is greater than the thermally conductive material 50 wrapped on the surface of the outer bracket 200.
  • FIG. 3 Wrap the inner and outer surfaces of the outer bracket 200 with the thermally conductive material 50 and the outer surface of the inner bracket 100 with the thermally conductive material 50.
  • the thickness of the heat conductive material on the surface of the inner bracket 100 is greater than that of the outer layer
  • the thermally conductive material on the surface of the bracket 200 reduces the heat treatment temperature of the inner bracket 100 to achieve lower fiber structure destruction and lower light transmittance.
  • Insulating material 60 is provided between the outer layer bracket 200 and the inner layer bracket 100.
  • the heat insulating material 60 may be a filler such as tin foil paper, aluminum foil paper, heat insulating sand or powder.
  • the heat insulating material can be used to achieve different heat treatment temperatures for the inner bracket 100 and the outer bracket 200.
  • the whole body is pressurized, heated, and cooled to obtain the stent graft 10.
  • the heating temperature is 400°C to 450°C. If the temperature is insufficient, the heat treatment will be insufficient, the coating material will not bond, and if the temperature is too high, the fiber will be completely destroyed, and the coating will lose its elasticity and toughness. Insulate at temperature for more than 20min, then quickly cool to room temperature. It should be noted that in other embodiments, an appropriate temperature and holding time may also be selected according to specific requirements.
  • a stent graft 10a includes an inner stent 100a and an outer stent 200a.
  • the outer stent 200a is sleeved on the inner stent 100a.
  • the outer stent 200a covers at least a portion of the inner stent 100a, one end of the outer layer bracket 200a is hermetically connected to the inner layer bracket 100a.
  • both the inner layer stent 100a and the outer layer stent 200a have radial compression capability, which can be compressed under the action of external force and self-expand or recover to its original shape by mechanical expansion (such as balloon expansion) after the external force is withdrawn. And maintain the original shape, so that after implanting the lumen, it can be fixed in the lumen by its radial support force against the lumen wall.
  • the inner stent 100a is a lumen structure with both ends open and closed in the middle. After the lumen is implanted, the inner stent 100a can be used as a new fluid channel, for example, a new blood flow channel after being implanted in a blood vessel.
  • One end of the outer layer stent 200a is sealingly connected to the outer peripheral surface of the inner layer stent 100a to form a closed nozzle, and the other end is open. After the outer layer stent 200a is released, it can be automatically deployed to fill the gap between the inner layer stent 100a and the lumen wall.
  • the stent graft 10a can be used for the reconstruction of branch vessels in the chimney technology. Please refer to FIG. 5 as well, which is a schematic structural diagram of the stent graft 10a as a branch stent and a main body stent 20a. After implantation, the proximal opening of the stent graft 10a and the main body stent 20a are aligned, and are arranged side by side in the main blood vessel 30a.
  • the proximal end surface of the outer stent 200a of the stent graft 10a can be at least the same as the proximal end surface of the main body stent 20a.
  • the proximal end surface of the inner stent 100a protrudes from the main body stent 20a, and the distal end of the inner stent 100a is inserted into the branch vessel for anchoring. Blood flow can enter the branch vessel through the pipeline built by the inner stent 100a. So as to reconstruct the branch blood vessels.
  • the proximal regions of the stent graft 10a and the main body stent 20a are radially compressed against each other in the main blood vessel 30a, and the outer stent 200a can conform to the morphology of the blood vessel wall and the main body stent 20a, thus A cavity is formed between the layered stent 200a and the inner layered stent 100a, and blood flowing into the cavity can be used as a filling material to block the type I endoleak channel to prevent blood flow from entering the tumor or interlayer, while ensuring the smoothness of the inner layered stent 100a. Blood can flow smoothly into branch blood vessels. It should be understood that the stent graft 10a can be used not only in conjunction with the body stent 20a but also in a stand-alone manner.
  • the outer layer bracket 200a includes a tapered section 201a and a straight pipe section 202a connected to the tapered section 201a.
  • the end of the tapered section 201a away from the straight pipe section 202a is connected to the inner layer bracket 100a.
  • One end of the tapered section 201a is hermetically connected to the inner stent 100a, and the other end radiates outward in the direction of the distal end pointing to the proximal end, forming an approximately conical structure.
  • the straight pipe section 202a is connected to the proximal end of the tapered section 201a and is connected to the inner layer
  • the brackets 100a are arranged in parallel.
  • the diameter of the straight pipe section 202a is not less than 1.5a times the diameter of the inner stent 100a, which can make the outer stent better adhere to the lumen wall and simultaneously conform to the external force deformation, better To prevent type I endoleaks. In one embodiment, the diameter of the straight pipe section 202a is not less than twice the diameter of the inner stent 100a.
  • the inner support includes an inner support frame 110a and an inner coating 120a disposed on the inner support frame 110a.
  • the inner support 110a and the inner coating 120a cooperate to form the side of the inner support 100a wall.
  • the outer layer bracket 200a includes an outer layer supporting skeleton 210a and an outer layer covering film 220a disposed on the outer layer supporting skeleton 210a.
  • the radial support force of the outer support skeleton 210a is smaller than the radial support force of the inner support skeleton 100a.
  • the outer stent 200a Due to the low radial support force of the outer support frame 210a, the outer stent 200a easily conforms to the deformation of the inner wall of the lumen, thereby avoiding the formation of a gap between the outer stent 200a and the inner wall of the lumen, and better avoiding type I endoleaks, and the inner layer
  • the radial support force of the support frame 110a is greater, and the inner stent 100 can be more closely attached to the lumen wall to fix the entire stent graft 10a in the lumen, avoiding displacement or detachment from the lumen.
  • Both the inner support frame 110a and the outer support frame 210a can be made of various biocompatible materials, including known materials used in the manufacture of implanted medical devices or a combination of various materials, such as 316L stainless steel, cobalt-chromium -Nickel-molybdenum-iron alloy, nickel-titanium alloy (Nitinol), or other biocompatible metals.
  • Both the inner layer supporting skeleton 110a and the outer layer supporting skeleton 210a may be woven from metal wires or formed by cutting a metal tube.
  • both the inner support frame 110a and the outer support frame 210a may include a multi-turn braided wave-shaped ring in the axial direction, such as a multi-turn Z-shaped wave; or include a spiral wound structure; or include a wire braid
  • the mesh structure may also be a cut mesh structure formed by cutting a metal tube.
  • both the inner support frame 110a and the outer support frame 210a are braided with nickel-titanium wires, and the outer support frame 210a uses a nickel-titanium wire with a smaller diameter than the nickel-titanium wire used for the inner support frame 110a.
  • the wire diameter is helpful to reduce the required sheath size of the stent graft 10a.
  • the outer layer coating film 220a and the inner layer coating film 120a are both made of PTFE film.
  • the inner layer coating film 120a wraps the inner support frame 110a by hot melting, and the outer layer coating film 220a wraps the outer support frame 210a by hot melting method. Wrapped, the outer layer coating 200a is hermetically connected to the outer surface of the inner layer coating 120a by means of hot melting.
  • the outer-layer coating 220a and the inner-layer coating 120a may not be limited to PTFE membranes, and may also be other materials with similar properties to PTFE.
  • the resilience of the outer layer coating 220a is greater than the resilience of the inner layer coating 120a.
  • the inner membrane 120a may wrinkle. Because the resilience of the inner membrane 120a is small, the straightening force of the inner stent 100a (i.e. The force of returning to the natural state from the bending state is smaller, which can reduce the stimulation of the inner layer stent 100a on the lumen wall, and the inner layer coating 120a will be relatively soft, which can help the inner layer stent to better conform to the bending and bending.
  • the shape of the blood vessel; meanwhile, the resilience of the inner membrane 120 is smaller, which can make the inner membrane 120a more deformable in the lumen.
  • the inner stent 100a When the inner stent 100a is implanted into the lesion, the inner stent 100a is punched under the blood flow
  • the inner layer 120a can expand and expand to a certain extent, which helps the inner stent 100 to better adhere to the wall and prevent blood from flowing into the lesion from the outer side of the inner stent 100a.
  • the outer layer 220a has more resilience Large, when the stent graft 10a is released, the outer membrane 220a can quickly rebound, which helps the outer stent 200a to better fill the gap between the inner stent 120a and the lumen wall, and effectively prevent internal leakage.
  • the resilience is measured according to DIN 53512 at 20°C using a Schob pendulum on the inner layer coating 120a and the outer layer coating 220a, respectively.
  • the inner layer coating 120a and the outer layer coating The films 220a were placed on the surface of a plastic test piece having a thickness of 12.5 mm and a resilience of 24%, respectively.
  • the resilience of the inner coating 120a is 10% to 15%, and the resilience of the outer coating 220a is 15% to 20%, which may help the inner stent 100a to better conform to the twists and turns
  • the anatomical shape of the blood vessel ensures that the stent graft 10a is unobstructed in the long term, and the outer membrane 220a is easier to expand after release, which can effectively prevent the occurrence of endoleaks.
  • the inner layer coating 120a and the outer layer coating 220a undergo the following test method: please refer to FIG. 7, and take a piece of the inner layer coating 120a and the outer layer of the same rectangular shape (for example, 20mm-10mm) respectively
  • the layer coating 220a is divided into area A and area B by the center line of its long side, and it is folded in half along the center line of the long side until area A and area B coincide. The angle between them no longer changes.
  • the angle between the area A and the area B in the outer layer coating 220a is 120° to 150°
  • the angle between the area A and the area B in the inner layer coating 120a is 90° to 130°
  • the outer layer coating 220a The angle between the area A and the area B is larger than the angle between the area A and the area B in the inner film, so that the outer film 220a can be quickly popped to fill the inner stent 100a after the outer stent 200a is released.
  • the gap between the luminal walls, and the outer stent 200a will not cause difficulty in sheathing and release due to the large angle, while the inner layer of the membrane 120a can be effectively deployed after release, and will not cause a relatively large angle. Big back straightness.
  • the thickness of the outer coating 220a is less than the thickness of the inner coating 120a, which can reduce the size of the sheath required for the stent 10a.
  • the thickness of the outer layer coating film 220 a is 10 ⁇ m to 50 ⁇ m
  • the thickness of the inner layer coating film 120 a is 20 ⁇ m to 70 ⁇ m.
  • the thickness of the inner layer coating 120a is 20 ⁇ m to 30 ⁇ m
  • the thickness of the outer layer coating 220a is 15 ⁇ m to 25 ⁇ m.
  • the present application also provides a method for preparing a stent graft 10a, including:
  • the layer support skeleton 110a is placed on the inner and outer surfaces, while the inner layer support skeleton 110a is sleeved on the inner mold 40a.
  • the inner mold 40a may be a fixing device of glass or metal material.
  • the inner and outer surfaces of the outer layer bracket 200a are wrapped by the outer mold 50a, and the outer surface of the inner layer bracket 100a is also covered by the outer mold 50a, wherein the thermal conductivity of the outer mold 50a is less than that of the inner mold 40a. Coefficient, or the thickness of the outer mold 50a is greater than the thickness of the inner mold 40a.
  • the heating temperature is 400°C to 450°C. Insufficient temperature will result in insufficient heat treatment, and the coating material cannot be bonded. Too high temperature will cause the coating to lose elasticity and toughness, and keep the temperature at this temperature for 30 minutes Above, then naturally cooled to room temperature. It should be noted that in other embodiments, an appropriate temperature and holding time may be selected according to specific requirements.
  • a stent graft 10b includes an inner stent 100b and an outer stent 200b.
  • the outer stent 200b is sleeved on the inner stent 100b.
  • the outer stent 200b covers at least a portion of the inner stent 100b, one end of the outer layer bracket 200b is hermetically connected to the inner layer bracket 100b.
  • both the inner layer stent 100b and the outer layer stent 200b have radial compression capability, which can be compressed under the action of external force and self-expand or recover to its original shape by mechanical expansion (such as balloon expansion) after the external force is withdrawn. And maintain the original shape, so that after implanting the lumen, it can be fixed in the lumen by its radial support force against the lumen wall.
  • the inner stent 100b is a lumen structure with two ends open and closed in the middle. After implantation into the lumen, the inner stent 100b can be used as a new fluid channel, for example, it can be used as a new blood flow channel after implantation into a blood vessel.
  • One end of the outer layer stent 200b is sealingly connected to the outer peripheral surface of the inner layer stent 100b to form a closed nozzle, and the other end is open. After the outer layer stent 200b is released, it can be automatically expanded to fill the gap between the inner layer stent 100b and the lumen wall.
  • the stent graft 10b can be used to reconstruct branch vessels in the chimney technology. Please also refer to FIG. 10, which is a schematic structural diagram of the stent graft 10b as a branch stent and a main body stent 20b. After implantation, the proximal opening of the stent graft 10b and the main body stent 20b are aligned and arranged side by side in the main blood vessel 30b.
  • the proximal end surface of the outer stent 200b of the stent graft 10b can be at least equal to the proximal end surface of the main body stent 20b Partially flush, the proximal end surface of the inner stent 100b protrudes from the main body stent 20b, the distal end of the inner stent 100b is inserted into the branch vessel for anchoring, and blood flow can enter the branch vessel through the pipeline built by the inner stent 100b. So as to reconstruct the branch blood vessels.
  • the proximal regions of the stent graft 10b and the main body stent 20b are radially compressed against each other in the main blood vessel 30b, and the outer stent 200b can conform to the morphology of the blood vessel wall and the main body stent 20b, thus A cavity is formed between the layered stent 200b and the inner layered stent 100b, and the blood flowing into the cavity can be used as a filling material to block the type I endoleak channel to prevent blood flow from entering the tumor or interlayer, while ensuring the smoothness of the inner layered stent 100b. Blood can flow smoothly into branch blood vessels. It should be understood that the stent graft 10b can be used not only in conjunction with the body stent 20b, but also in a stand-alone manner.
  • the outer layer bracket 200b includes a tapered section 201b and a straight pipe section 202b connected to the tapered section 201b.
  • the end of the tapered section 201b away from the straight pipe section 202b is connected to the inner layer bracket 100b.
  • One end of the tapered section 201b is hermetically connected to the inner stent 100b, and the other end radiates outward in the direction that the distal end points to the proximal end, forming an approximately conical structure.
  • the straight pipe section 202b is connected to the proximal end of the tapered section 201b and is connected to the inner layer
  • the brackets 100b are arranged in parallel.
  • the diameter of the straight tube section 202b is not less than 1.5 times the diameter of the inner stent 100b, which can make the outer stent better adhere to the lumen wall and simultaneously conform to the external force deformation, better Prevent type I endoleak. In one embodiment, the diameter of the straight pipe section 202b is not less than twice the diameter of the inner stent 100b.
  • the inner support includes an inner support frame 110b and an inner coating 120b disposed on the inner support frame 110b.
  • the inner support 110b and the inner coating 120b cooperate to form the side of the inner support 100b wall.
  • the outer layer support 200b includes an outer layer supporting skeleton 210b and an outer layer covering film 220 disposed on the outer layer supporting skeleton 210.
  • the radial support force of the outer support skeleton 210 is less than the radial support force of the inner support skeleton 110b.
  • the outer stent 200b Due to the low radial support force of the outer support frame 210b, the outer stent 200b easily conforms to the deformation of the inner wall of the lumen, thereby avoiding the formation of a gap between the outer stent 200b and the inner wall of the lumen, and better avoiding type I endoleak, and the inner layer
  • the radial support force of the support frame 110b is greater, and the inner stent 100b can be more closely attached to the lumen wall to fix the entire stent graft 10b in the lumen, avoiding displacement or detachment from the lumen.
  • Both the inner support frame 110b and the outer support frame 210b can be made of various biocompatible materials, including known materials used in implanted medical device manufacturing or a combination of various materials, such as 316L stainless steel, cobalt-chromium -Nickel-molybdenum-iron alloy, nickel-titanium alloy (Nitinol), or other biocompatible metals.
  • Both the inner layer supporting skeleton 110b and the outer layer supporting skeleton 210b may be woven from metal wires or formed by cutting a metal tube.
  • both the inner support frame 110b and the outer support frame 210b may include a wave-shaped loop formed by multiple turns of braiding in the axial direction, such as multiple turns of Z-shaped waves; or a spiral wound structure; or a wire braid
  • the mesh structure may also be a cut mesh structure formed by cutting a metal tube.
  • a person of ordinary skill in the art may select a suitable inner layer supporting structure 110b and an outer layer supporting structure according to needs, which will not be repeated here.
  • both the inner support frame 110b and the outer support frame 210b are formed by braiding nickel-titanium wires, and the outer support frame 210b uses a nickel-titanium wire with a smaller wire diameter than the inner-layer support frame 110b. The wire diameter is helpful to reduce the required sheath size of the stent graft 10b.
  • Both the outer layer coating 220b and the inner layer coating 120b use PTFE films.
  • the inner layer coating 120b wraps the inner and outer surfaces of the inner support frame 110b by hot melting, and the outer layer coating 220b wraps the outer layer by hot melting
  • the inner and outer surfaces of the support frame 210b are wrapped, and the outer layer coating 200b is hermetically connected to the outer surface of the inner layer coating 120b by means of hot melting.
  • the outer-layer coating 220b and the inner-layer coating 120b may not be limited to PTFE membranes, and may also be other materials with properties similar to PTFE.
  • the tensile strength of the outer layer coating 220b is greater than the tensile strength of the inner layer coating 120b, and the elongation of the outer layer coating 220b is less than the elongation of the inner layer coating 120b.
  • the area of the outer stent 200b of the stent graft 10b has the largest loading cross-sectional area, so the friction force of the outer membrane 220b of the outer stent 200b is particularly large during assembly and release.
  • the tensile strength of the inner layer film 120b is relatively small, that is, under the same conditions, under the tensile force less than the tensile strength, the amount of deformation of the inner layer film 120 will be greater, which can make the inner layer film 120b can better conform to the curved blood vessel morphology.
  • the elongation of the outer layer coating 220b is less than the elongation of the inner layer coating 120b, the elongation of the inner layer coating 120b is larger, which can make the inner layer coating 120b be released after the stent graft 10b is released.
  • the tensile strength test can refer to the standard YY 0500-2018.
  • the test method is as follows: by axially stretching the sheet-like coating material (for example, 25 mm in width), and recording the stretch to break Peak force during the process.
  • the shape of the dumbbell-shaped sample can refer to the type I dumbbell sample in the standard GB/t528-2009 or ISO 37:2005, and the film thickness of the dumbbell sample is the same as the film thickness of the stent graft to be tested.
  • the tensile strength of the outer layer coating 220b is not less than 30N, and the elongation is 5% to 15%.
  • the tensile strength of the inner layer coating 120b is not less than 20N, and the elongation is 10% to 30%.
  • the material of the outer coating 220b is completely the same as the material of the inner coating 120b.
  • the thickness of the outer coating 220b is less than the thickness of the inner coating 120b, which can reduce the sheath required for the stent 10b The size of the tube.
  • the thickness of the outer layer coating 220b is 10 ⁇ m to 50 ⁇ m
  • the thickness of the inner layer coating 120b is 20 ⁇ m to 70 ⁇ m.
  • the inner layer coating 120b has a thickness of 20 ⁇ m to 30 ⁇ m
  • the outer layer coating has a thickness of 15 ⁇ m to 25 ⁇ m.
  • the peeling force of the outer layer coating 220b is not less than the peeling force of the inner layer coating 120b.
  • the peeling force of the outer-layer coating 220b is not less than 1 N/mm to prevent the outer-layer coating 220 from being separated from the outer-layer supporting skeleton 210b under the scouring of blood flow, thereby improving the stability of the stent-graft 10b.
  • the peeling force can be tested by the following method: separating the sheet-like coating material (for example, 25 mm in width) by a tensile machine, and recording the force value during the tearing process.
  • the present application also provides a method for preparing a stent graft 10b, including:
  • the mold 40b may be a metal material fixing device.
  • the rotational speed of the mold 40b is 2 to 4 weeks per minute, and it is taken out after holding for 30 minutes.
  • the outer layer covering film 220b is covered on the inner and outer surfaces of the outer layer supporting skeleton 210b, and at the same time, the outer layer supporting skeleton 210b is sleeved on the mold 40b, so that the outer layer bracket 200b and the mold 40b are bonded together.
  • the assembly structure of the outer layer structure and the mold 40b is the same as the assembly structure of the inner layer bracket 100b and the mold 40b.
  • the rotation speed of the mold 40b is 2 to 4 weeks per minute, and it is taken out after holding for 40 minutes.
  • the shape of the mold 40b can be adjusted according to the shapes of the inner stent 100b and the outer stent 200b.
  • the outer layer bracket 200b may be fixed on the inner layer bracket 100b by hot melting or stitching.

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Abstract

一种覆膜支架（10），包括：可径向压缩的内层支架（100），内层支架（100）包括内层支撑骨架（110）及设置于内层支撑骨架（110）上的内层覆膜（120）；套设于内层支架（100）上的外层支架（200），外层支架（200）至少覆盖部分内层支架（100），外层支架（200）包括外层支撑骨架（210）及设置于外层支撑骨架（210）上的外层覆膜（220），外层覆膜（220）一端与内层覆膜（120）密封连接，外层覆膜（220）的透光率大于内层覆膜（120）的透光率。覆膜支架（10）有助于内层支架（100）实现弯曲变形，提高内层支架（100）的柔顺性及贴壁性，外层覆膜（220）之间不易发生相互粘结，有利于降低覆膜支架（10）的释放阻力。还提供一种覆膜支架（10）的制备方法。

Description

覆膜支架及其制备方法 技术领域
本发明涉及医疗器械领域，特别是涉及一种覆膜支架及其制备方法。
背景技术
现有的覆膜支架一般由金属支架和防渗漏的覆膜构成，覆膜材料可以为塑料、涤纶、聚酯。例如，塑料可以为聚四氟乙烯(PTFE)，聚酯可以为聚对苯二甲酸乙二醇酯(PET)或聚氨基甲酸乙酯(PU)等。其中PET和PTFE为最常用的两种材料。PET材质的覆膜一般采用手工缝合的方式固定在金属支架上，而PTFE材质的覆膜具有延伸率高易变形，且高温状态下会融化相互粘合的特性，该特性使PTFE材质更容易实现内外PTFE膜高温粘合将金属支架固定在覆膜中的加工工艺，较手工缝合的方式有明显的效率优势。同时PTFE材料本身具有的纤维状微孔结构也使得它生物相容性更好，易于细胞爬覆。
发明内容
本发明的目的是提供一种覆膜支架及其制备方法。
一种覆膜支架，包括：
可径向压缩的内层支架，所述内层支架包括内层支撑骨架及设置于所述内层支撑骨架上的内层覆膜；
套设于所述内层支架上的外层支架，所述外层支架至少覆盖部分所述内层支架，所述外层支架包括外层支撑骨架及设置于所述外层支撑骨架上的外层覆膜，所述外层覆膜的一端与所述内层覆膜密封连接，所述外层覆膜的透光率大于所述内层覆膜的透光率。
一种覆膜支架的制备方法，包括：
将外层支架固定在内层支架上，并将所述内层支架固定在模具上；
在所述内层支架的表面与所述外层支架的表面包裹导热材料，其中所述内层支架的表面包裹的导热材料的厚度大于所述外层支架的表面包裹的导热材料；
在所述外层支架与所述内层支架之间设置隔热材料；
将上述整体进行加压、加热处理，并冷却，得到所述覆膜支架。
上述覆膜支架，通过设置外层覆膜的透光率大于内层覆膜的透光率，内层覆膜的透光率较低，内层覆膜微观的纤维结构会比较完整，使得内层覆膜的生物相容性较好，植入后细胞更易爬覆，同时内层支架也可以具有较好的弹性，有助于内层支架实现弯曲变形，提高内层支架的柔顺性及贴壁性，而外层覆膜的透光率较高，可以使得外层覆膜较内层支架更光滑，在装入鞘管后，外层覆膜之间不易发生相互粘结，有利于降低覆膜支架的释放阻力，而且释放后外层覆膜更容易恢复到原始尺寸，实现与管腔壁间隙的封堵。
一种覆膜支架，包括：
可径向压缩的内层支架，所述内层支架包括内层支撑骨架及设置于所述内层支撑骨架上的内层覆膜；
套设于所述内层支架上的外层支架，所述外层支架至少覆盖部分所述内层支架，所述外层支架包括外层支撑骨架及设置于所述外层支撑骨架上的外层覆膜，所述外层覆膜的一端与所述内层覆膜密封连接，所述外层覆膜的回弹性大于所述内层覆膜的回弹性。
上述覆膜支架，由于内层覆膜的回弹性较小，内层支架的回直力(即由弯曲状态恢复至自然状态的力)较小，可以降低内层支架对管腔壁的刺激，而且 内层覆膜会相对较柔软，可以有助于内层支架较好地顺应弯曲曲折的血管形态；同时内层覆膜的回弹性较小，可以使得内层覆膜在管腔内更易变形，当内层支架植入到病变位置时，内层支架在血流冲压下，内层覆膜可以出现一定程度的膨胀扩张，从而有利于内层支架更好地贴壁，防止血液从内层支架的外侧流入病变位置，另外，外层支架的回弹性较大，当覆膜支架释放后，外层覆膜可以快速回弹，有助于外层支架较好地填补内层支架与管腔壁的缝隙，有效防止内漏。
一种覆膜支架，包括：
可径向压缩的内层支架，所述内层支架包括内层支撑骨架及设置于所述内层支撑骨架上的内层覆膜；
套设于所述内层支架上的外层支架，所述外层支架至少覆盖部分所述内层支架，所述外层支架包括外层支撑骨架及设置于所述外层支撑骨架上的外层覆膜，所述外层覆膜的一端与所述内层覆膜密封连接，所述外层覆膜的拉伸强度大于所述内层覆膜的拉伸强度，且所述外层覆膜的延伸率小于所述内层覆膜的延伸率。
上述覆膜支架，通过设置外层支架的外层覆膜的拉伸强度大于内层支架的内层覆膜的拉伸强度，以避免外层覆膜在装载过程中或释放过程中断裂，降低覆膜支架失效的风险，而内层覆膜的拉伸强度较小，即，在同等条件下，在小于拉伸强度作用力的拉伸下，内层覆膜的变形量会较大，可以使得内层覆膜可以较好地顺应弯曲的血管形态。而通过设置外层覆膜的延伸率小于内层覆膜的延伸率，内层覆膜的延伸率较大，可以使得内层覆膜在覆膜支架释放后，可以在血流压力的作用下适当变形膨胀，使内层支架可以更好地贴合血管壁，减少内漏发生的概率，而外层覆膜的延伸率较小，可以使得外层覆膜在装载和释放过程不容易变形。
附图说明
图1本申请一实施例的覆膜支架的结构示意图；
图2为图1所示的覆膜支架与主体支架配合植入血管后的结构示意图；
图3为图1所示的覆膜支架在制备过程中的示意图；
图4本申请另一实施例的覆膜支架的结构示意图；
图5为图4所示的覆膜支架与主体支架配合植入血管后的结构示意图；
图6为图4所示的内层支架由自然状态到弯曲状态的结构示意图；
图7为内层覆膜或外层覆膜在测试过程中的结构示意图；
图8为图4所示的覆膜支架在制备过程中的示意图
图9本申请又一实施例的覆膜支架的结构示意图；
图10为图9所示的覆膜支架与主体支架配合植入血管后的结构示意图；
图11为图9所示的覆膜支架装载到鞘管后的结构示意图；
图12为图9所示的覆膜支架在制备过程中的示意图。
具体实施方式
为使本发明的上述目的、特征和优点能够更加明显易懂，下面结合附图对本发明的具体实施方式做详细的说明。在下面的描述中阐述了很多具体细节以便于充分理解本发明。但是本发明能够以很多不同于在此描述的其它方式来实施，本领域技术人员可以在不违背本发明内涵的情况下做类似改进，因此本发明不受下面公开的具体实施的限制。
需要说明的是，当元件被称为“固定于”或“设置于”另一个元件，它可以直接在另一个元件上或者也可以存在居中的元件。当一个元件被认为是“连接”另一个 元件，它可以是直接连接到另一个元件或者可能同时存在居中元件。本文所使用的术语“垂直的”、“水平的”、“左”、“右”以及类似的表述只是为了说明的目的，并不表示是唯一的实施方式。
除非另有定义，本文所使用的所有的技术和科学术语与属于本发明的技术领域的技术人员通常理解的含义相同。本文中在本发明的说明书中所使用的术语只是为了描述具体的实施方式的目的，不是旨在于限制本发明。本文所使用的术语“及/或”包括一个或多个相关的所列项目的任意的和所有的组合。
为方便描述，以血管为例来阐述管腔，该血管可以是主动脉弓，或胸主动脉，或腹主动脉等。本领域的普通技术人员应当知晓，采用血管来阐述仅用作举例，并不是对本发明的限制，本发明的方案适用于各种人体管腔，例如消化道管腔等，基于本发明教导的各种改进和变形均在本发明的保护范围之内。另外，在阐述血管中，可按照血流方向定义方位，本发明中定义血流从近端流向远端。
请参阅图1，本发明的覆膜支架10包括内层支架100及外层支架200，外层支架200套设于内层支架100上，外层支架200至少覆盖部分内层支架100，外层支架200的一端与内层支架100密封连接。
具体而言，内层支架100及外层支架200均具有径向压缩能力，可在外力作用下可被压缩并在外力撤销后自膨胀或通过机械膨胀(例如球囊扩张膨胀)恢复至初始形状并保持初始形状，由此植入管腔后可通过其径向支撑力紧贴管腔壁而固定于管腔内。内层支架100为两端开口、中间封闭的管腔结构，植入管腔后，内层支架100可作为新的流体通道，例如植入血管后可作为新的血流通道。外层支架200的一端与内层支架100的外周表面密封连接，形成封闭管口，另一端开放，外层支架200释放后可以自动展开以填充内层支架100与管腔壁之间的缝隙。
覆膜支架10可用于烟囱技术中分支血管的重建，请一并参阅图2，其为覆膜支架10作为分支支架与主体支架20配合的结构示意图。植入后，覆膜支架10与主体支架20近端开口朝向一致，且并排设于主血管30中，覆膜支架10的外层支架200的近端端面可与主体支架20的近端端面至少部分齐平，内层支架100的近端端面伸出主体支架20，内层支架100的远端则置入分支血管中进行锚定，血流可以通过内层支架100搭建的管道进入分支血管，从而起到重建分支血管的作用。当主血管30的脉动收缩时，覆膜支架10与主体支架20的近端区域在主血管30内相互径向挤压，外层支架200可顺应血管壁及主体支架20的形貌变形，从而在外层支架200与内层支架100之间形成空腔，流入该空腔的血液可作为填充材料封堵Ⅰ型内漏通道，避免血流进入瘤体或夹层处，同时确保内层支架100通畅，血液可顺利流入分支血管。应当知晓，覆膜支架10不仅可以与主体支架20配合使用，也可以单独使用。
在图示的实施例中，外层支架200包括锥度段201及与锥度段201连接的直管段202，锥度段201远离直管段202的一端与内层支架100连接。锥度段201的一端与内层支架100密封连接，另一端沿远端指向近端的方向向外辐射展开，形成近似锥形结构，直管段202与锥度段201的近端连接，并与内层支架100平行设置。为了提高外层支架200的封堵效果，直管段202的直径不小于内层支架100的直径的1.5倍，可以使得外层支架较好地贴附管腔壁并同时顺应外力变形，较好地阻止Ⅰ型内漏。在一实施例中，直管段202的直径不小于内层支架100的直径的2倍。
请继续参阅图1，内层支架包括内层支撑骨架110及设置于内层支撑骨架 110上的内层覆膜120，内层支撑骨架110与内层覆膜120配合形成内层支架100的侧壁。外层支架200包括外层支撑骨架210及设置于外层支撑骨架210上的外层覆膜220。在一实施例中，外层支撑骨架210的径向支撑力小于内层支撑骨架100的径向支撑力。由于外层支撑骨架210的径向支撑力较小，外层支架200易于顺应管腔内壁变形，从而避免在外层支架200与管腔内壁形成间隙，较好地避免Ⅰ型内漏，而且内层支撑骨架110的径向支撑力较大，内层支架100可以较紧密地贴附在管腔壁上而使整个覆膜支架10固定于管腔中，避免移位或从管腔中脱离。
内层支撑骨架110及外层支撑骨架210均可由各种生物相容的材料制成，包括植入医疗器械制造中所使用的已知材料或各种材料的组合，例如316L不锈钢、钴-铬-镍-钼-铁合金、镍钛合金(镍钛诺)，或其它生物相容的金属。内层支撑骨架110及外层支撑骨架210均可以由金属丝编织而成或由金属管切割形成。例如，内层支撑骨架110及外层支撑骨架210均可沿轴向包括多圈编织形成的波形环状物，如多圈Z形波；或者包括螺旋缠绕结构；或者包括金属丝编织而成的网状结构，也可以是通过金属管切割而成的切割网状结构。本领域的普通技术人员可根据需要选择合适的内层支撑结构110及外层支撑结构，此处不再赘述。在本实施例中，内层支撑骨架110及外层支撑骨架210均采用镍钛丝编织形成，外层支撑骨架210采用的镍钛丝的丝径小于内层支撑骨架110采用的镍钛丝的丝径，有利于降低覆膜支架10所需的鞘管尺寸。
外层覆膜220及内层覆膜120均采用PTFE膜，内层覆膜120通过热熔的方式将内层支撑骨架110包裹，外层覆膜220通过热熔的方式将外层支撑骨架210包裹，外层覆膜200通过热熔的方式与内层覆膜120的外表面密封连接。
外层覆膜220的透光率大于内层覆膜120的透光率。透光率与覆膜材料的微观特征相关。以PTFE为例说明，PTFE膜原材料的透光率较低，通过工艺处理后成品覆膜材料的透光率越低，其表面特性会越接近原材料，即微观纤维结构越完整，此时覆膜成品更柔然，更易变形，同时具有一定的粘性，而随着工艺条件的强化(如增加加热时间等)，覆膜材料表面纤维结构发生融合，成品覆膜材料的透光率会进一步上升，体现出不同的物理特性，覆膜成品的硬度会更高，更光滑，同时也无法拉伸。通过设置外层覆膜220的透光率大于内层覆膜120的透光率，内层覆膜120的透光率较低，内层覆膜120微观的纤维结构会比较完整，使得内层覆膜120的生物相容性较好，植入后细胞更易爬覆，同时内层支架120也可以具有较好的弹性，有助于内层支架100实现弯曲变形，提高内层支架100的柔顺性及贴壁性，而外层覆膜220的透光率较高，可以使得外层覆膜220较内层支架210更光滑，在装入鞘管后，外层覆膜220之间不易发生相互粘结，有利于降低覆膜支架10的释放阻力，而且释放后外层覆膜220更容易恢复到原始尺寸，实现与管腔壁间隙的封堵。当然，在其他实施例中，外层覆膜220与内层覆膜120也可以不局限于PTFE膜，也可以为其他与PTFE性质类似的材料。
在本申请中，透光率是透过物体的光通量与照射到物体的光通量的比值，即当入射光的强度I 0一定时，介质吸收光的强度I a越大，则透过光的强度I t越小，用I t/I 0表示光线透过介质的能力，称为透光率，以T表示，即，T＝I t/I 0。本申请中的透光率可使用分光光度计进行测试。
在一实施例中，内层覆膜120的透光率小于50％，外层覆膜220的透光率为50％～70％，可以有助于内层支架100能较好地顺应曲折的血管解剖形态，保证覆膜支架10远期的通畅，外层覆膜220表面较光滑，可以降低覆膜支架10 的释放阻力，而且外层覆膜220释放后较易展开，可以有效防止内漏的发生。
在一实施例中，外层覆膜220的厚度小于内层覆膜120的厚度，可以降低覆膜支架10所需的鞘管的尺寸。具体的，外层覆膜220的厚度为10μm～50μm，内层覆膜120的厚度为20μm～70μm。在一实施例中，内层覆膜120的透光率为30％～48％，厚度为20μm～30μm，外层覆膜220的透光率为60％～70％，外层覆膜的厚度为15μm～25μm。
本申请还提供一种覆膜支架10的制备方法，包括：
S11、将外层支架200固定在内层支架100上，并将内层支架100固定在模具40上。
具体地，请一并参阅图3，将外层支撑骨架210与内层支撑骨架120固定，将外层覆膜220覆盖在外层支撑骨架210的内外表面上，将内层覆膜120覆盖在内层支撑骨架110的内外表面上，同时将内层支撑骨架110套在模具40上。模具40可以为玻璃或金属材料的固定装置上。
S12、在内层支架100的表面与外层支架200的表面包裹导热材料50，其中内层支架100的表面包裹的导热材料50的厚度大于外层支架200的表面包裹的导热材料50。
具体地，请一并参阅图3，将外层支架200的内外表面包裹导热材料50，将内层支架100的外表面包裹导热材料50，其中内层支架100表面的导热材料的厚度大于外层支架200表面的导热材料，以此降低内层支架100热处理温度，实现较低的纤维结构破坏，实现较低的透光率。
S13、在外层支架200与内层支架100之间设置隔热材料60。
在本实施例中，隔热材料60可以为锡箔纸、铝箔纸、隔热沙粒或粉末等填充物，通过隔热材料，以实现内层支架100与外层支架200不同的热处理温度。
S14、将上述整体进行加压、加热处理，并冷却，得到覆膜支架10。
在本实施例中，加热的温度为400℃～450℃，温度不够会导致热处理不充分，覆膜材料无法粘合，温度过高会导致纤维完全破坏，覆膜失去弹性和韧性，并在此温度下保温20min以上，随后快速冷却至室温。需要说明的是，在其他实施例中，也可以根据具体的要求，选择合适的温度及保温时间。
请参阅图4，本发明另一实施例的覆膜支架10a包括内层支架100a及外层支架200a，外层支架200a套设于内层支架100a上，外层支架200a至少覆盖部分内层支架100a，外层支架200a的一端与内层支架100a密封连接。
具体而言，内层支架100a及外层支架200a均具有径向压缩能力，可在外力作用下可被压缩并在外力撤销后自膨胀或通过机械膨胀(例如球囊扩张膨胀)恢复至初始形状并保持初始形状，由此植入管腔后可通过其径向支撑力紧贴管腔壁而固定于管腔内。内层支架100a为两端开口、中间封闭的管腔结构，植入管腔后，内层支架100a可作为新的流体通道，例如植入血管后可作为新的血流通道。外层支架200a的一端与内层支架100a的外周表面密封连接，形成封闭管口，另一端开放，外层支架200a释放后可以自动展开以填充内层支架100a与管腔壁之间的缝隙。
覆膜支架10a可用于烟囱技术中分支血管的重建，请一并参阅图5，其为覆膜支架10a作为分支支架与主体支架20a配合的结构示意图。植入后，覆膜支架10a与主体支架20a近端开口朝向一致，且并排设于主血管30a中，覆膜支架10a的外层支架200a的近端端面可与主体支架20a的近端端面至少部分齐平，内层支架100a的近端端面伸出主体支架20a，内层支架100a的远端则置入分支血管中进行锚定，血流可以通过内层支架100a搭建的管道进入分支血管，从而起到 重建分支血管的作用。当主血管30a的脉动收缩时，覆膜支架10a与主体支架20a的近端区域在主血管30a内相互径向挤压，外层支架200a可顺应血管壁及主体支架20a的形貌变形，从而在外层支架200a与内层支架100a之间形成空腔，流入该空腔的血液可作为填充材料封堵Ⅰ型内漏通道，避免血流进入瘤体或夹层处，同时确保内层支架100a通畅，血液可顺利流入分支血管。应当知晓，覆膜支架10a不仅可以与主体支架20a配合使用，也可以单独使用。
在图示的实施例中，外层支架200a包括锥度段201a及与锥度段201a连接的直管段202a，锥度段201a远离直管段202a的一端与内层支架100a连接。锥度段201a的一端与内层支架100a密封连接，另一端沿远端指向近端的方向向外辐射展开，形成近似锥形结构，直管段202a与锥度段201a的近端连接，并与内层支架100a平行设置。为了提高外层支架200a的封堵效果，直管段202a的直径不小于内层支架100a的直径的1.5a倍，可以使得外层支架较好地贴附管腔壁并同时顺应外力变形，较好地阻止Ⅰ型内漏。在一实施例中，直管段202a的直径不小于内层支架100a的直径的2倍。
请继续参阅图4，内层支架包括内层支撑骨架110a及设置于内层支撑骨架110a上的内层覆膜120a，内层支撑骨架110a与内层覆膜120a配合形成内层支架100a的侧壁。外层支架200a包括外层支撑骨架210a及设置于外层支撑骨架210a上的外层覆膜220a。在一实施例中，外层支撑骨架210a的径向支撑力小于内层支撑骨架100a的径向支撑力。由于外层支撑骨架210a的径向支撑力较小，外层支架200a易于顺应管腔内壁变形，从而避免在外层支架200a与管腔内壁形成间隙，较好地避免Ⅰ型内漏，而且内层支撑骨架110a的径向支撑力较大，内层支架100可以较紧密地贴附在管腔壁上而使整个覆膜支架10a固定于管腔中，避免移位或从管腔中脱离。
内层支撑骨架110a及外层支撑骨架210a均可由各种生物相容的材料制成，包括植入医疗器械制造中所使用的已知材料或各种材料的组合，例如316L不锈钢、钴-铬-镍-钼-铁合金、镍钛合金(镍钛诺)，或其它生物相容的金属。内层支撑骨架110a及外层支撑骨架210a均可以由金属丝编织而成或由金属管切割形成。例如，内层支撑骨架110a及外层支撑骨架210a均可沿轴向包括多圈编织形成的波形环状物，如多圈Z形波；或者包括螺旋缠绕结构；或者包括金属丝编织而成的网状结构，也可以是通过金属管切割而成的切割网状结构。本领域的普通技术人员可根据需要选择合适的内层支撑结构110a及外层支撑结构，此处不再赘述。在本实施例中，内层支撑骨架110a及外层支撑骨架210a均采用镍钛丝编织形成，外层支撑骨架210a采用的镍钛丝的丝径小于内层支撑骨架110a采用的镍钛丝的丝径，有利于降低覆膜支架10a所需的鞘管尺寸。
外层覆膜220a及内层覆膜120a均采用PTFE膜，内层覆膜120a通过热熔的方式将内层支撑骨架110a包裹，外层覆膜220a通过热熔的方式将外层支撑骨架210a包裹，外层覆膜200a通过热熔的方式与内层覆膜120a的外表面密封连接。然，在其他实施例中，外层覆膜220a与内层覆膜120a也可以不局限于PTFE膜，也可以为其他与PTFE性质类似的材料。
外层覆膜220a的回弹性大于内层覆膜120a的回弹性。请参阅图6，当内层支架100a发生轴向压缩或弯曲时，内层覆膜120a会发生褶皱，由于内层覆膜120a的回弹性较小，内层支架100a的回直力(即由弯曲状态恢复至自然状态的力)较小，可以降低内层支架100a对管腔壁的刺激，而且内层覆膜120a会相对较柔软，可以有助于内层支架较好地顺应弯曲曲折的血管形态；同时内层覆膜120的回弹性较小，可以使得内层覆膜120a在管腔内更易变形，当内层支架100a 植入到病变位置时，内层支架100a在血流冲压下，内层覆膜120a可以出现一定程度的膨胀扩张，从而有利于内层支架100更好地贴壁，防止血液从内层支架100a的外侧流入病变位置，另外，外层支架220a的回弹性较大，当覆膜支架10a释放后，外层覆膜220a可以快速回弹，有助于外层支架200a较好地填补内层支架120a与管腔壁的缝隙，有效防止内漏。
在本申请中，回弹性是根据DIN 53512，在20℃下，使用Schob摆锤分别在内层覆膜120a及外层覆膜220a上测量的，测量时，内层覆膜120a及外层覆膜220a分别放置在厚度为12.5mm并且回弹性为24％的塑料测试片的表面上。
在一实施例中，内层覆膜120a的回弹性为10％～15％，外层覆膜220a的回弹性为15％～20％，可以有助于内层支架100a能较好地顺应曲折的血管解剖形态，保证覆膜支架10a远期的通畅，而且外层覆膜220a释放后较易展开，可以有效防止内漏的发生。
在一实施例中，内层覆膜120a及外层覆膜220a经过如下测试方法：请参阅图7，分别取一片大小相同的矩形状(例如，20mm～10mm)的内层覆膜120a及外层覆膜220a，其长边的中线分别将其分成A区域及B区域，并将其沿长边的中线对折至A区域与B区域重合，静置使其自然恢复至A区域与B区域之间的角度不再发生变化。外层覆膜220a中A区域与B区域之间的角度为120°～150°，内层覆膜120a中A区域与B区域之间的角度为90°～130°，且外层覆膜220a中A区域与B区域之间的角度大于内层覆膜中A区域与B区域之间的角度，这样外层覆膜220a在外层支架200a释放后能够快速地弹开以填充内层支架100a与管腔壁之间的间隙，而且外层支架200a不会由于角度太大而导致装鞘和释放困难，而内层覆膜120a在释放后可以有效展开，而且不会由于角度过大而产生较大的回直力。
在一实施例中，外层覆膜220a的厚度小于内层覆膜120a的厚度，可以降低覆膜支架10a所需的鞘管的尺寸。具体的，外层覆膜220a的厚度为10μm～50μm，内层覆膜120a的厚度为20μm～70μm。在一实施例中，内层覆膜120a的厚度为20μm～30μm，外层覆膜220a的厚度为15μm～25μm。
本申请还提供一种覆膜支架10a的制备方法，包括：
S11a、将外层支架200a固定在内层支架100a上，并将内层支架100a固定在内40a上。
具体地，请一并参阅图5，将外层支撑骨架210a与内层支撑骨架120a固定，将外层覆膜220a覆盖在外层支撑骨架210a的内外表面上，将内层覆膜120a覆盖在内层支撑骨架110a的内外表面上，同时将内层支撑骨架110a套在内模40a上。内模40a可以为玻璃或金属材料的固定装置上。
S12a、将外模50a套在内层支架100a上，并使外模50a覆盖外层支架200a的外表面，其中外模50a的导热系数小于内模40a的导热系数，或者外模50a的厚度大于内模40a的厚度，并使得外模50a与内模40a充分贴合。
具体地，请一并参阅图8，外层支架200a的内外表面被外模50a包裹，内层支架100a的外表面也被外模50a覆盖，其中外模50a的导热系数小于内模40a的导热系数，或者外模50a的厚度大于内模40a的厚度。
S13a、将上述整体进行加压、加热处理，保温一段时间后，打开外模50a，并自然冷却至室温，得到覆膜支架10a。
在本实施例中，加热的温度为400℃～450℃，温度不够会导致热处理不充分，覆膜材料无法粘合，温度过高会导致覆膜失去弹性和韧性，并在此温度下保温30min以上，随后自然冷却至室温。需要说明的是，在其他实施例中，也可以根 据具体的要求，选择合适的温度及保温时间。
请参阅图9，本发明又一实施例的覆膜支架10b包括内层支架100b及外层支架200b，外层支架200b套设于内层支架100b上，外层支架200b至少覆盖部分内层支架100b，外层支架200b的一端与内层支架100b密封连接。
具体而言，内层支架100b及外层支架200b均具有径向压缩能力，可在外力作用下可被压缩并在外力撤销后自膨胀或通过机械膨胀(例如球囊扩张膨胀)恢复至初始形状并保持初始形状，由此植入管腔后可通过其径向支撑力紧贴管腔壁而固定于管腔内。内层支架100b为两端开口、中间封闭的管腔结构，植入管腔后，内层支架100b可作为新的流体通道，例如植入血管后可作为新的血流通道。外层支架200b的一端与内层支架100b的外周表面密封连接，形成封闭管口，另一端开放，外层支架200b释放后可以自动展开以填充内层支架100b与管腔壁之间的缝隙。
覆膜支架10b可用于烟囱技术中分支血管的重建，请一并参阅图10，其为覆膜支架10b作为分支支架与主体支架20b配合的结构示意图。植入后，覆膜支架10b与主体支架20b近端开口朝向一致，且并排设于主血管30b中，覆膜支架10b的外层支架200b的近端端面可与主体支架20b的近端端面至少部分齐平，内层支架100b的近端端面伸出主体支架20b，内层支架100b的远端则置入分支血管中进行锚定，血流可以通过内层支架100b搭建的管道进入分支血管，从而起到重建分支血管的作用。当主血管30b的脉动收缩时，覆膜支架10b与主体支架20b的近端区域在主血管30b内相互径向挤压，外层支架200b可顺应血管壁及主体支架20b的形貌变形，从而在外层支架200b与内层支架100b之间形成空腔，流入该空腔的血液可作为填充材料封堵Ⅰ型内漏通道，避免血流进入瘤体或夹层处，同时确保内层支架100b通畅，血液可顺利流入分支血管。应当知晓，覆膜支架10b不仅可以与主体支架20b配合使用，也可以单独使用。
在图示的实施例中，外层支架200b包括锥度段201b及与锥度段201b连接的直管段202b，锥度段201b远离直管段202b的一端与内层支架100b连接。锥度段201b的一端与内层支架100b密封连接，另一端沿远端指向近端的方向向外辐射展开，形成近似锥形结构，直管段202b与锥度段201b的近端连接，并与内层支架100b平行设置。为了提高外层支架200b的封堵效果，直管段202b的直径不小于内层支架100b的直径的1.5倍，可以使得外层支架较好地贴附管腔壁并同时顺应外力变形，较好地阻止Ⅰ型内漏。在一实施例中，直管段202b的直径不小于内层支架100b的直径的2倍。
请继续参阅图9，内层支架包括内层支撑骨架110b及设置于内层支撑骨架110b上的内层覆膜120b，内层支撑骨架110b与内层覆膜120b配合形成内层支架100b的侧壁。外层支架200b包括外层支撑骨架210b及设置于外层支撑骨架210上的外层覆膜220。在一实施例中，外层支撑骨架210的径向支撑力小于内层支撑骨架110b的径向支撑力。由于外层支撑骨架210b的径向支撑力较小，外层支架200b易于顺应管腔内壁变形，从而避免在外层支架200b与管腔内壁形成间隙，较好地避免Ⅰ型内漏，而且内层支撑骨架110b的径向支撑力较大，内层支架100b可以较紧密地贴附在管腔壁上而使整个覆膜支架10b固定于管腔中，避免移位或从管腔中脱离。
内层支撑骨架110b及外层支撑骨架210b均可由各种生物相容的材料制成，包括植入医疗器械制造中所使用的已知材料或各种材料的组合，例如316L不锈钢、钴-铬-镍-钼-铁合金、镍钛合金(镍钛诺)，或其它生物相容的金属。内层支撑骨架110b及外层支撑骨架210b均可以由金属丝编织而成或由金属管切割形 成。例如，内层支撑骨架110b及外层支撑骨架210b均可沿轴向包括多圈编织形成的波形环状物，如多圈Z形波；或者包括螺旋缠绕结构；或者包括金属丝编织而成的网状结构，也可以是通过金属管切割而成的切割网状结构。本领域的普通技术人员可根据需要选择合适的内层支撑结构110b及外层支撑结构，此处不再赘述。在本实施例中，内层支撑骨架110b及外层支撑骨架210b均采用镍钛丝编织形成，外层支撑骨架210b采用的镍钛丝的丝径小于内层支撑骨架110b采用的镍钛丝的丝径，有利于降低覆膜支架10b所需的鞘管尺寸。
外层覆膜220b及内层覆膜120b均采用PTFE膜，内层覆膜120b通过热熔的方式将内层支撑骨架110b的内外表面包裹，外层覆膜220b通过热熔的方式将外层支撑骨架210b的内外表面包裹，外层覆膜200b通过热熔的方式与内层覆膜120b的外表面密封连接。然，在其他实施例中，外层覆膜220b与内层覆膜120b也可以不局限于PTFE膜，也可以为其他与PTFE性质类似的材料。
外层覆膜220b的拉伸强度大于内层覆膜120b的拉伸强度，外层覆膜220b的延伸率小于内层覆膜120b的延伸率。请一并参阅图11，覆膜支架10b通过径向挤压装载于输送器的鞘管50b后，由于此时覆膜支架10b处于径向压缩状态，因此在鞘管50b内部，覆膜支架10b的自膨胀趋势导致覆膜支架10b的外表面与鞘管50b内壁的接触面积较大，这也导致覆膜支架10b的外表面覆膜在装载和释放过程中都需要承受较大的摩擦力，而覆膜支架10b的外层支架200b的区域装载截面积最大，因而在装配和释放时外层支架200b的外层覆膜220b的所受的摩擦力尤为大，通过设置外层支架200b的外层覆膜220b的拉伸强度大于内层支架100的内层覆膜120的拉伸强度，以避免外层覆膜220在装载过程中或释放过程中断裂，降低覆膜支架10b失效的风险，而内层覆膜120b的拉伸强度较小，即，在同等条件下，在小于拉伸强度作用力的拉伸下，内层覆膜120的变形量会较大，可以使得内层覆膜120b可以较好地顺应弯曲的血管形态。而通过设置外层覆膜220b的延伸率小于内层覆膜120b的延伸率，内层覆膜120b的延伸率较大，可以使得内层覆膜120b在覆膜支架10b释放后，可以在血流压力的作用下适当变形膨胀，使内层支架100b可以更好地贴合血管壁，减少内漏发生的概率，而外层覆膜220b的延伸率较小，可以使得外层覆膜220b在装载和释放过程不容易变形。
在本申请中，拉伸强度的测试可以参照标准YY 0500-2018，具体的，测试方法如下：通过对片状覆膜材料(例如宽度为25mm)进行轴向拉伸，并记录拉伸至断裂过程中力的峰值。
延伸率可以采用如下方法测得：对于给定规格的覆膜支架，其直径为D1，将覆膜做成哑铃状试样其窄部宽10mm，在窄部标记长度L0的覆膜，在环境温度37℃±2℃情况下对试样施加F＝25kpa*10mm*D1*0.5≈0.125*D1牛顿的拉力，覆膜48小时后窄部原标定长度L0长度变为L1，延伸率μ＝(L1-L0)/L0。其中，哑铃状试样形状可以参考标准GB/t528-2009或者ISO 37:2005中I型哑铃试样，哑铃试样的膜厚与被测试覆膜支架覆膜厚度相同。
在一实施例中，外层覆膜220b的拉伸强度不小于30N，延伸率为5％～15％。内层覆膜120b的拉伸强度不小于20N，且延伸率为10％～30％。
在一实施例中，外层覆膜220b的材质与内层覆膜120b的材质完全相同，外层覆膜220b的厚度小于内层覆膜120b的厚度，可以降低覆膜支架10b所需的鞘管的尺寸。具体的，外层覆膜220b的厚度为10μm～50μm，内层覆膜120b的厚度为20μm～70μm。在一实施例中，内层覆膜120b厚度为20μm～30μm，外层覆膜的厚度为15μm～25μm。
在一实施例中，外层覆膜220b的剥离力不小于内层覆膜120的剥离力。外层覆膜220b的剥离力不小于1N/mm，以防止外层覆膜220在血流的冲刷下，外层覆膜220b与外层支撑骨架210b分离，提高覆膜支架10b的稳定性。在本申请中，剥离力的测试可以采用如下方法：通过拉力机分离片状覆膜材料(例如宽度为25mm)，记录撕裂过程中的力值。
本申请还提供一种覆膜支架10b的制备方法，包括：
S11b、将内层支架100b固定在模具40b上，加热至温度为290℃～300℃，当温度稳定后使模具40沿周向匀速转动，一段时间后取出并自然冷却。
具体地，请一并参阅图12，将内层覆膜120b覆盖在内层支撑骨架110b的内外表面上，同时将内层支撑骨架110b套在模具40b上，使内层支架100b与模具40b贴合。模具40b可以为金属材料的固定装置上。在一实施例中，模具40b的转速为每分钟2～4周，保温30min后取出。
S12、将外层支架200b固定在模具40b上，加热至温度为300℃～320℃，当温度稳定后使模具40b沿周向匀速转动，一段时间后取出并自然冷却。
具体地，将外层覆膜220b覆盖在外层支撑骨架210b的内外表面上，同时将外层支撑骨架210b套在模具40b上，使外层支架200b与模具40b贴合。外层结构与模具40b组装结构与内层支架100b与模具40b的组装结构相同。在一实施例中，模具40b的转速为每分钟2～4周，保温40min后取出。
需要说明的是，模具40b的形状可以根据内层支架100b及外层支架200b的形状进行调整。
S13b、将外层支架200b固定在内层支架100b上，得到覆膜支架10b。
具体地，可以通过热熔或者缝合等方式将外层支架200b固定在内层支架100b上。
以上所述实施例的各技术特征可以进行任意的组合，为使描述简洁，未对上述实施例中的各个技术特征所有可能的组合都进行描述，然而，只要这些技术特征的组合不存在矛盾，都应当认为是本说明书记载的范围。
以上所述实施例仅表达了本发明的几种实施方式，其描述较为具体和详细，但并不能因此而理解为对发明专利范围的限制。应当指出的是，对于本领域的普通技术人员来说，在不脱离本发明构思的前提下，还可以做出若干变形和改进，这些都属于本发明的保护范围。因此，本发明专利的保护范围应以所附权利要求为准。

Claims (30)

  1. 一种覆膜支架，其特征在于，包括：
    可径向压缩的内层支架，所述内层支架包括内层支撑骨架及设置于所述内层支撑骨架上的内层覆膜；
    套设于所述内层支架上的外层支架，所述外层支架至少覆盖部分所述内层支架，所述外层支架包括外层支撑骨架及设置于所述外层支撑骨架上的外层覆膜，所述外层覆膜的一端与所述内层覆膜密封连接，所述外层覆膜的透光率大于所述内层覆膜的透光率。
  2. 根据权利要求1所述的覆膜支架，其特征在于，所述内层覆膜的透光率小于50％，所述外层覆膜的透光率为50％～70％。
  3. 根据权利要求1所述的覆膜支架，其特征在于，所述外层覆膜的厚度小于所述内层覆膜的厚度。
  4. 根据权利要求3所述的覆膜支架，其特征在于，所述外层覆膜的厚度为10μm～50μm，所述内层覆膜的厚度为20μm～70μm。
  5. 根据权利要求1所述的覆膜支架，其特征在于，所述内层覆膜及所述外层覆膜均采用PTFE膜。
  6. 根据权利要求1所述的覆膜支架，其特征在于，所述外层支撑骨架的径向支撑力小于所述内层支架的径向支撑力。
  7. 根据权利要求6所述的覆膜支架，其特征在于，所述外层支撑骨架及所述内层支撑骨架均采用金属丝编织形成，且所述外层支撑骨架采用的金属丝的丝径小于所述内层支撑骨架采用的金属丝的丝径。
  8. 根据权利要求1所述的覆膜支架，其特征在于，所述外层支架包括锥度段及与所述锥度段连接的直管段，所述锥度段远离所述直管段的一端与所述内层支架密封连接。
  9. 根据权利要求8所述的覆膜支架，其特征在于，所述直管段的直径不小于所述内层支架的直径的1.5倍
  10. 一种制备如权利要求1～9任一所述的覆膜支架的方法，其特征在于，包括：
    将外层支架固定在内层支架上，并将所述内层支架固定在模具上；
    在所述内层支架的表面与所述外层支架的表面包裹导热材料，其中所述内层支架的表面包裹的导热材料的厚度大于所述外层支架的表面包裹的导热材料；
    在所述外层支架与所述内层支架之间设置隔热材料；
    将上述整体进行加压、加热处理，并冷却，得到所述覆膜支架。
  11. 一种覆膜支架，其特征在于，包括：
    可径向压缩的内层支架，所述内层支架包括内层支撑骨架及设置于所述内层支撑骨架上的内层覆膜；
    套设于所述内层支架上的外层支架，所述外层支架至少覆盖部分所述内层支架，所述外层支架包括外层支撑骨架及设置于所述外层支撑骨架上的外层覆膜，所述外层覆膜的一端与所述内层覆膜密封连接，所述外层覆膜的回弹性大于所述内层覆膜的回弹性。
  12. 根据权利要求11所述的覆膜支架，其特征在于，所述外层覆膜的回弹性为15％～20％，所述内层覆膜的回弹性为10％～15％。
  13. 根据权利要求11所述的覆膜支架，其特征在于，所述外层覆膜的厚度小于所述内层覆膜的厚度。
  14. 根据权利要求13所述的覆膜支架，其特征在于，所述外层覆膜的厚度为10μm～50μm，所述内层覆膜的厚度为20μm～70μm。
  15. 根据权利要求11所述的覆膜支架，其特征在于，所述外层覆膜和所述内层覆膜在经如下测试方法：
    分别取一片大小相同的矩形状的所述内层覆膜和所述外层覆膜，其长边的中线将其分为A区域及B区域，并将其沿长边的中线对折至A区域与B区域重合，静置使其自然恢复至A区域与B区域之间的角度不再发生变化；
    所述外层覆膜中A区域与B区域之间的角度为120°～150°，所述内层覆膜中A区域与B区域之间的角度为90°～130°，且所述外层覆膜中A区域与B区域之间的角度大于所述内层覆膜中A区域与B区域之间的角度。
  16. 根据权利要求11所述的覆膜支架，其特征在于，所述内层覆膜及所述 外层覆膜均采用PTFE膜。
  17. 根据权利要求11所述的覆膜支架，其特征在于，所述外层支撑骨架的径向支撑力小于所述内层支架的径向支撑力。
  18. 根据权利要求17所述的覆膜支架，其特征在于，所述外层支撑骨架及所述内层支撑骨架均采用金属丝编织形成，且所述外层支撑骨架采用的金属丝的丝径小于所述内层支撑骨架采用的金属丝的丝径。
  19. 根据权利要求11所述的覆膜支架，其特征在于，所述外层支架包括锥度段及与所述锥度段连接的直管段，所述锥度段远离所述直管段的一端与所述内层支架密封连接。
  20. 根据权利要求19所述的覆膜支架，其特征在于，所述直管段的直径不小于所述内层支架的直径的1.5倍。
  21. 一种覆膜支架，其特征在于，包括：
    可径向压缩的内层支架，所述内层支架包括内层支撑骨架及设置于所述内层支撑骨架上的内层覆膜；
    套设于所述内层支架上的外层支架，所述外层支架至少覆盖部分所述内层支架，所述外层支架包括外层支撑骨架及设置于所述外层支撑骨架上的外层覆膜，所述外层覆膜的一端与所述内层覆膜密封连接，所述外层覆膜的拉伸强度大于所述内层覆膜的拉伸强度，且所述外层覆膜的延伸率小于所述内层覆膜的延伸率。
  22. 根据权利要求21所述的覆膜支架，其特征在于，所述外层覆膜的拉伸强度不小于30N，且延伸率为5％～15％。
  23. 根据权利要求21所述的覆膜支架，其特征在于，所述内层覆膜的拉伸强度不小于20N，且延伸率为10％～30％。
  24. 根据权利要求21所述的覆膜支架，其特征在于，所述外层覆膜的厚度小于所述内层覆膜的厚度。
  25. 根据权利要求24所述的覆膜支架，其特征在于，所述外层覆膜的厚度为10μm～50μm，所述内层覆膜的厚度为20μm～70μm。
  26. 根据权利要求21所述的覆膜支架，其特征在于，所述内层覆膜及所述 外层覆膜均采用PTFE膜，且所述外层覆膜的剥离力不小于所述内层覆膜的剥离力。
  27. 根据权利要求21所述的覆膜支架，其特征在于，所述外层支撑骨架的径向支撑力小于所述内层支架的径向支撑力。
  28. 根据权利要求7所述的覆膜支架，其特征在于，所述外层支撑骨架及所述内层支撑骨架均采用金属丝编织形成，且所述外层支撑骨架采用的金属丝的丝径小于所述内层支撑骨架采用的金属丝的丝径。
  29. 根据权利要求21所述的覆膜支架，其特征在于，所述外层支架包括锥度段及与所述锥度段连接的直管段，所述锥度段远离所述直管段的一端与所述内层支架密封连接。
  30. 根据权利要求29所述的覆膜支架，其特征在于，所述直管段的直径不小于所述内层支架的直径的1.5倍。
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