EP2879730A1 - Stent enrobé - Google Patents

Stent enrobé

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Publication number
EP2879730A1
EP2879730A1 EP13734758.9A EP13734758A EP2879730A1 EP 2879730 A1 EP2879730 A1 EP 2879730A1 EP 13734758 A EP13734758 A EP 13734758A EP 2879730 A1 EP2879730 A1 EP 2879730A1
Authority
EP
European Patent Office
Prior art keywords
coating
range
carrier
sec
medical implant
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP13734758.9A
Other languages
German (de)
English (en)
Inventor
Bruno Covelli
Nicolas MATHYS
Original Assignee
AXETIS AG
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
Application filed by AXETIS AG filed Critical AXETIS AG
Publication of EP2879730A1 publication Critical patent/EP2879730A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • A61L31/08—Materials for coatings
    • A61L31/082—Inorganic materials
    • A61L31/088—Other specific inorganic materials not covered by A61L31/084 or A61L31/086
    • 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
    • A61F2/844—Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents folded prior to deployment
    • 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
    • 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
    • A61L2400/00—Materials characterised by their function or physical properties
    • A61L2400/16—Materials with shape-memory or superelastic properties
    • 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
    • A61L2400/00—Materials characterised by their function or physical properties
    • A61L2400/18—Modification of implant surfaces in order to improve biocompatibility, cell growth, fixation of biomolecules, e.g. plasma treatment
    • 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
    • A61L2420/00—Materials or methods for coatings medical devices
    • A61L2420/02—Methods for coating medical devices

Definitions

  • the present invention relates to a Si0 2 -containing coating for a medical implant, in particular a vessel stent, and a medical implant with a Si0 2 -containing coating and a method for producing the coating and the implant.
  • Stents are used for the purpose of keeping serene, such as blood vessels (eg arteriosclerosis) in the occlusion-vulnerable vessels.This can either be done by means of a catheter or by surgically opening the vessel, if necessary Stents are generally tubular tubular structures, such as tissue tubing or tubular porous structures, which conform to the inner wall of a vessel and maintain a free flow area through which the blood in the blood vessel can flow freely.
  • blood vessels eg arteriosclerosis
  • Stents are generally tubular tubular structures, such as tissue tubing or tubular porous structures, which conform to the inner wall of a vessel and maintain a free flow area through which the blood in the blood vessel can flow freely.
  • stents are used in biliary tract, trachea or esophagus.
  • stents are used to limit the narrowing of the airways, biliary tract or esophagus after stretching has taken place.
  • Stents often consist of tubes with reticulate wall, which have a small diameter and thus can be easily brought by means of a catheter to the destination, where it by means of a balloon (balloon catheter) in the vessel by stretching the reticulated wall of the stent on the necessary lumen and so that the necessary diameter for supporting the vessel can be expanded.
  • a balloon balloon catheter
  • Balloon expandable stents are typically made of a moldable metallic material, such as stainless steel or nickel-titanium alloys. stents are usually formed by making selected structures from tubes of the desired material. Examples of such machining methods include, for example, spark erosion (EDM) based on metal erosion by spark deposition, or laser beam treatment in which a narrow, high energy density beam of light is used to vaporize selected portions of the metal pipe cut.
  • EDM spark erosion
  • laser beam treatment in which a narrow, high energy density beam of light is used to vaporize selected portions of the metal pipe cut.
  • the surface finish i. the roughness or roughness of stents outside and inside (Ra AD & ID) in the machine-made state is usually about 0.4 ⁇ .
  • stents can be electropolished after machine fabrication.
  • the principles of electropolishing per se, especially in the context of stainless steel alloys, are well known in the art.
  • the prosthesis By coating the prosthesis, e.g. It prevents platelet aggregation and damage to the balloon catheter, and minimizes surface roughness.
  • Si0 2 -containing coatings, with or without additives can in principle be applied by known methods, such as by chemical vapor deposition (chemical vapor deposition).
  • the rough surface of the stent may provide blood cells (e.g., platelets, i.e. platelets) with a surface which promotes adhesion. Adhesion of such platelets to the rough surface of a supporting prosthesis can trigger the sequence of steps, known as a coagulation cascade, which, in severe cases, can lead to the formation of a blood clot in and / or around the implanted prosthesis. If such a clot persists in this position, it may happen that the vascular closure, which the vascular prosthesis should actually prevent, reappears. If the clot separates from the stent and travels into the arterial or venous vasculature, it may eventually settle to a remote location in the body where it blocks blood flow and causes an infarction or blow.
  • blood cells e.g., platelets, i.e. platelets
  • Adhesion of such platelets to the rough surface of a supporting prosthesis can trigger the sequence of steps, known as a coagulation cascade, which, in severe
  • Another negative effect of a rough surface of a vascular graft is the formation of unwanted microturbulences in the blood flow at that surface.
  • the blood flow is diverted to the smallest bulges. This deflection leads to the smallest vertebrae. Cell components can be trapped in these vertebrae and also trigger the above-mentioned coagulation cascade, with the associated disadvantages and hazards to the patient.
  • the invention is directed to an improved medical implant and method for making such an implant, the implant having a coating containing silica.
  • the coating except for incompletely oxidized starting material, consists essentially of silicon dioxide.
  • the medical implant is a vascular stent, for example for blood vessels, bile ducts, esophagus or trachea.
  • EP 1 752 113 A1 discloses a vessel stent which is suitable for the coating according to the invention or as a carrier for an implant according to the invention.
  • the subject of the present invention is a coating for a medical implant, in particular a tubular support prosthesis, which comprises silicon dioxide.
  • the tubular support prosthesis may be a vascular stent, such as a venous stent or an arterial stent, where the arterial stent may be deployed in the coronary artery or in the aorta.
  • the stent may advantageously comprise one or more artificial and / or tissue engineered valves, eg, an aortic valve.
  • Previously known stents have the problem that, because of their specific surface area and their lattice structure, they often grow or grow from the body's own cells, which in the longer term can in turn lead to a renewed occlusion of the stent-protected vessel (restenosis).
  • restenosis stent-protected vessel
  • conventional stent coatings are not always flexible enough to participate in the movements of the stent during implantation and expansion, which can lead to damage to the coating.
  • the thickness of the coating is approximately in the same range as the maximum tolerance for surface roughness in the prosthesis. As a result, the coating reflects the surface properties of the prosthesis, including the surface imperfections within the determined roughness tolerances of the underlying denture substrate.
  • the thickness of the coating according to the invention is preferably 40 to 150 nm. According to a preferred embodiment, the coating thickness is in the range of 60-120 nm, preferably 80-100 nm, particularly preferably in the range of about 80 nm. The thickness is thus preferably just that chosen that there is a continuous layer that does not break during movement or expansion of the implant, and preferably remains elastic at least in the working area.
  • the coating may be applied in a single step, thus forming a monolayer, but in a preferred embodiment may also consist of a plurality of successively applied layers.
  • the composition of each individual layer can be determined individually.
  • the silica may be in the coating in amorphous or crystalline or semi-crystalline form.
  • the properties of the coating may be further modified by at least one admixture contained in the coating, wherein the admixture may be selected from alumina, titania, calcium compounds, sodium oxide, germania, magnesia, selenium oxide and hydroxides, especially hydroxides of the aforementioned metals.
  • Particularly preferred admixtures are alumina and titania.
  • the proportion of the admixture in the total amount of the coating may preferably be 0.5 to 50% by weight.
  • the coating be substantially nonporous.
  • the coating may also be preferred that the coating has pores for functionalization with other substances that are applied to the coating after the actual coating and deposit in the pores.
  • the coating according to the invention may have an additional, even partially or punctually present functionalization order.
  • Such an order may correspond to the medical purpose of the medical implant and include affecting the growth of surrounding tissue, killing unwanted tissue, establishing a relationship between the medical implant and tissue, etc.
  • the functionalization order may contain, for example, at least one drug and / or at least one cell poison.
  • the erfmdungsgemässe coating preferably has a maximum average defect size of 0.5-2 ⁇ , preferably of about 1 ⁇ on. This means that any cracks or other damage in the Si0 2 layer preferably have a smaller diameter than 1 ⁇ , or that the mean value of all defects on the Coating surface before and / or after the expansion 0.5-2 ⁇ , preferably about 1 ⁇ amounts.
  • a system for plasma-induced chemical vapor deposition for example a PECVD reactor: plasma-enhanced chemical vapor deposition
  • a PECVD reactor plasma-enhanced chemical vapor deposition
  • Plasma polymerization is a special plasma-activated variant of chemical vapor deposition.
  • vaporous organic precursor compounds (precursors) in the process chamber are first activated by a plasma.
  • the activation produces free charge carriers (ions and electrons) and first coating elements in the form of precursor fragments and / or clusters or chains of these fragments are already formed in the gas phase.
  • the subsequent condensation of these coating elements on the substrate surface, here the stent surface then effects the polymerization and thus the formation of a closed layer under the influence of substrate temperature, electron bombardment and ion bombardment.
  • Such a method preferably includes the following properties:
  • a process gas stream containing at least one gas (eg argon, Ar) and / or a gaseous oxidant (eg C0 2 , N 2 0, 0 3 or 0 2 ) and a carrier gas stream containing at least one precursor are introduced into a treatment zone at least one substrate is located.
  • the volume of the treatment zone is enclosed by the evacuatable process chamber.
  • the process gas and carrier gas streams have at least one spatially separated inlet location in the treatment zone.
  • Advantageous are several inlet locations each for process gas stream and carrier gas stream. These may pass through one or more holes in the wall of at least one, for example ring, rod, string or otherwise Hollow body (gas shower) can be realized.
  • the at least one gas shower is connected to the treatment zone via said holes.
  • the holes have characteristic widths in the range of 0.1-10 mm, preferably 0.2-0.5 mm.
  • annular gas showers are preferably used, which are advantageously integrated in the vessel wall.
  • At least one preferably anisothermal, electrical gas discharge is operated in the process chamber.
  • the generation of an electrical potential gradient is necessary, with the aid of at least one plasma source, by means of which the energy supply is preferably done by radio frequency (RF) - or microwave (MW) - feed.
  • the voltage across the path is applied between at least two electrodes (ground electrode and counter electrode).
  • the electrodes can be arranged inside and outside the relationship at least one electrode outside and at least one other within the process chamber.
  • At least one electrode may be part or all of the wall of the process chamber.
  • this is the ground electrode.
  • both several spatially separated plasma zones can be achieved, as well as a single contiguous plasma zone.
  • the mixture of none, one or both already plasma-activated gas streams can be activated in at least one plasma zone.
  • the at least one plasma zone can fill the entire treatment zone or make up only a partial region of the treatment zone.
  • the substrate is located downstream relative to said inlet locations of process gas flow and / or carrier gas flow.
  • the substrate may be located inside or outside the at least one plasma zone.
  • the at least one substrate is supported by one of the aforementioned electrodes, or by a support device supported by it.
  • the at least one substrate can be moved freely in the treatment zone and thus switch between direct plasma activation (substrate within a plasma zone) or remoter plasma activation (afterglow) during coating.
  • a heterogeneous, chemical reaction of the coating elements takes place on the surface of the substrate.
  • RF mode RF plasma source
  • a holding device in the form of a plate
  • individual, electrically insulating holding elements rests on the counter electrode arranged inside the process chamber.
  • active cooling of the counter electrode is also used (e.g., by means of an integral water heat exchanger) to further reduce the heat load.
  • a cooling temperature in the range of TE 15-45 ° C., preferably of 18 ° C.-25 ° C. and more preferably of approx. 20 ° C., has proved to be advantageous.
  • the following parameters are important parameters for achieving a homogeneous and smooth surface: wall temperature of the process chamber TPK (preferably 50 ° C.), pressure p, injected plasma power PRF, gas composition during the cleaning and coating process (ratio of Gas volume flows [0 2 ] / [argon], [0 2 ] / [HMDSO]), coating time t ß , and positioning of the samples in the reactor.
  • the coating step may be preceded on a case-by-case basis by a fine plasma cleaning, the concentration of gaseous oxygen preferably being 100 sccm for 2 ⁇ 10 sec (sccm: standard cubic centimeter per minute).
  • concentration of gaseous oxygen preferably being 100 sccm for 2 ⁇ 10 sec (sccm: standard cubic centimeter per minute).
  • the other parameters correspond to those of the coating step.
  • O 2 and hexamethyldisiloxane are used as starting materials for the plasma polymerization, the oxygen being used as excitation gas and the hexamethyldisiloxane as layer former (precursor).
  • a ratio of [0 2 ] to [HMDSO] (silicon organic monomer) of in the range from 10: 1 to 40: 1 is particularly advantageous, in particular in the range from 10: 1 to 20: 1.
  • a ratio of [0 2 ] to [HMDSO] of 14: 1 to 18: 1, particularly preferably of about 15: 1 is used.
  • HMDSO is not completely oxidized. This means that at least part of the starting material is present in chain or net form in the final product. Preferably, only 80-95%, preferably about 90% of the starting material is fully reacted, or only 80-95%, preferably about 90% of the starting material are in Chain and / or net shape in the layer before.
  • the resulting coating has optimum mechanical properties for the purpose of implantation and cooperates in a particularly advantageous manner with the surface of the implant.
  • a flow rate of 0 2 of 60 sccm is used, with a flow rate of HMD SO of about 4 sccm, a preferred plasma power of 200 W, a preferred coating time of 2 x 6 sec and a preferred reactor pressure of 0.14 mbar ,
  • a great advantage of the medical implants according to the invention is the fact that the coating can be applied extremely thinly, namely preferably in the nano range, that is in the range of a few atomic layers. This makes it possible to essentially adjust the final dimensions in the production of the medical implant, without having to take account of possibly not exactly foreseeable dimensioning changes through the coating. In addition, such a thin coating is less prone to breakage.
  • the invention is furthermore directed to a medical implant which has a support, which is produced in particular according to the parameters described above and forms a basic structure, and a coating which contains or consists of silicon dioxide on at least parts of the support.
  • the coating is a coating according to the invention of the first aspect of the invention.
  • the medical implant is a vascular stent.
  • the vascular stent may be for a blood vessel, bile duct, esophagus, or trachea, and may be used in various animal species such as humans, domestic animals, and farm animals.
  • the support is preferably constructed from a material which is difficult to disassemble, "hard degradable” being understood to mean a property in which the material shows no visible signs of degradation after being implanted in a body for at least a year
  • the support is preferably made of medical implants Materials, in particular carbon, PTFE, Dacron, metal alloys, or PHA comprising constructed, in particular iron or steel alloys are preferred materials.
  • Another preferred material for the wearer is a shape memory metal, particularly nickel-titanium alloys, which find use in stents because of their ability to independently change their shape. But it can also be an aluminum alloy, Magnesium alloy or iron alloy can be used.
  • the invention is likewise directed to a method for producing a coated medical implant, in particular a medical implant according to the invention, which has at least the following steps:
  • the carrier is, as mentioned above, preferably made of a tubular metal blank of stainless steel by cutting the blank in a laser cutting process.
  • the laser cuts a stent structure.
  • the design drawing of the stents is converted by means of software into a format understandable for the CNC-controlled laser cutter, the so-called sectional drawing (CNC: computerized numerical control).
  • CNC computerized numerical control
  • the further supply is preferably fully automatic.
  • the first stent of a production batch is checked immediately after cutting for its uniform structure and cutting defects.
  • the optical control is carried out under a microscope. Under cutting errors contours are to be understood contrary to the sectional drawing.
  • a precise measurement of the stent takes place by means of profile projector or measuring microscope. If all parameters correspond to the specifications, then the tube processing will continue.
  • the laser cutting process preferably has one or more of the following parameters:
  • a particularly preferred laser cutting process is characterized by one or more of the following parameters:
  • a preferred pickling solution consists of deionized water, nitric acid (HN0 3 ) and hydrofluoric acid (HF).
  • a particularly preferred composition contains 75-80%, preferably 77.5% deionized water, 18-19%, preferably 18.3% nitric acid, and 4-4.5%, preferably 4.2% hydrofluoric acid, heated to 60-70 ° C, preferably 65.5 ° C.
  • the stents are electropolished.
  • an electropolishing article is immersed in an electrolyte containing an aqueous acid solution.
  • the article is made a positive electrode (anode) while a negative electrode (cathode) is placed near the anode.
  • the anode and cathode are then connected to a source of electrical potential difference, the electrolyte closing the circuit between the anode and cathode.
  • metal melts from the anode surface, ie, from the surface of the medical implant to be polished, eg, the tubular support prosthesis.
  • protruding portions are generally melted faster than indentations, so that it comes to a smoothing of the surface.
  • the rate of material removal during electropolishing is primarily a function of the electrolyte and the current density in the electrolyte-liquid.
  • attempts are made to maximize efficiency. This is achieved after mechanical production from the metal tube during electropolishing by increasing the speed, for example by increasing the acid concentration in the electrolyte bath, and / or by increasing the Current density. While such measures can often satisfactorily reduce surface roughness so that the above-mentioned coagulation disadvantages can be avoided or at least avoided in vivo, the inventors have found that acceleration of the electropolishing process also results in very sharp edges of the cut from the metal tube Sections can lead.
  • the rapid removal of material from the inner, outer and inner intersecting (transverse) surfaces may cause the remaining portions of the edges to collapse, resulting in sharp metallic edges where the abraded surfaces intersect.
  • Such sharp intersections may interfere with the implantation process in which the stent is deployed by means of a balloon catheter.
  • the balloon may be damaged by the sharp edges, resulting in a pressure drop within the balloon catheter. This can prevent the full expansion of the stent, which is necessary for the stent to optimally abut the vessel. In such situations, the balloon catheter must be removed and the stent lost in the body, leading to life-threatening complications.
  • Even in cases where the balloon itself is not damaged and the stent is properly immobilized in the correct position, a sharp-edged stent can still cause significant complications.
  • the sharp edges of the stent can namely be pressed against the vessel inner wall and gradually lead to irritation. Inflammation processes at the site of stent expansion may thus be triggered, and in severe cases, scarring may lead to vessel narrowing or
  • the stents are suspended on a frame of noble metal wires, which in turn is connected to a polishing plant.
  • the frame can be equipped, for example, with four wires, each with up to 20 stents.
  • the assembled rack is retracted into the electropolishing bath.
  • the current flow, the temperature and the polishing time as well as the amount of charge are regulated.
  • a planetary gear on the polishing frame ensures a uniform movement of the wires with the stents.
  • the polishing fluid is a special mixture of different acids.
  • the quality of the polishing fluid is monitored with an aerometer. With the help of a fine balance, each stent is weighed, and possibly polished, to ensure the target weight to +/- 0.2 mg.
  • the electropolishing of the carrier takes place in an electrolyte bath.
  • This advantageously contains at least phosphoric acid, sulfuric acid and distilled water.
  • the electropolishing is carried out at a temperature of 70-74 degrees Celsius, preferably at a temperature of 70.3-73.5 degrees Celsius.
  • the rotational speed is set to 2-6 mm / sec, preferably about 4 mm / sec.
  • the maximum applied voltage is in the range of 3-4 V, and is about 3.5 V, preferably a maximum of 3.11 V. It flows preferably a maximum current in the range of 3-7 A, preferably of at most 5 A.
  • the maximum average defect size at the support surface is advantageously 0.5-2 ⁇ , preferably about 1 ⁇ , i. the carrier should have no damage with a diameter greater than 0.5-2 ⁇ , preferably no damage with a diameter greater than about 1 ⁇ .
  • the still uncoated carrier advantageously has an average surface roughness R a of at most approximately 30 nm, preferably of at most 20 nm.
  • the average roughness R a indicates the average distance of a measurement point on the surface to a center line.
  • the centerline intersects the true profile within the datum line so that the sum of the profile deviations (relative to the centerline) becomes minimal.
  • the average roughness R a thus corresponds to the arithmetic mean of the deviation from a center line.
  • the roughness on the surface is standardized with ISO 25178.
  • the roughness characteristic can be measured over a wide area using optical measuring devices (eg with the optical microscope VHX100OOvon eyence, with a software-assisted 3D surface analysis and a resolution of 54 MPixel in combination with an up to 2500x optical magnification lens from Zeiss a virtual cut through the surface and determines the average roughness depth for this measuring range.).
  • optical measuring devices eg with the optical microscope VHX100OOvon eyence, with a software-assisted 3D surface analysis and a resolution of 54 MPixel in combination with an up to 2500x optical magnification lens from Zeiss a virtual cut through the surface and determines the average roughness depth for this measuring range.
  • platelets i. Platelets
  • i. Platelets usually vary in size between 2-4 ⁇ , can be ensured by adherence to the maximum surface roughness that no platelets catch on the implant, which in turn reduces the risk of unwanted complications due to prosthesis-induced blood clotting.
  • the definition of a range of surface roughness is further important because the coating applied to the surface is dynamic, or flexible, i. should not remain rigid, but at the same time should not slip off the Stromoberfikiee.
  • the quality of the surface to be coated thus plays an essential role in layer formation.
  • the method comprises the step of generating pores in the coating by means of neutron bombardment.
  • Neutron sources such as particle accelerators can be used for this purpose.
  • Another variant for producing functional pores is to produce the pores by means of laser light.
  • the present invention provides a coating for medical implants, in particular vascular stents, which due to their inert, glassy surface with silicon dioxide largely prevents growth of cells of the body or attachment of such cells, which due to their hardness damage during insertion of the implant counteracts in the body and thus simplifies the handling, which allows a simpler design of the implant due to the thinness of the coating, a reduced friction due to lower roughness and thus a smaller burden on blood components and low coagulum has and in it even after prolonged retention time in the body There is no degradation of the coating.
  • FIG. 1 shows an embodiment of an inventive electropolished stent prior to its coating
  • Fig. 2 is a three-dimensional microscopic view of a section of the
  • FIG. 3 shows a three-dimensional microscopic view of a section of a coated stent according to the invention, shown in an Olympus SZX12 light microscope, photographed by an Olympus ColorView Illu
  • FIG. 3 a three-dimensional microscopic view of a section of the inventive coated stent of FIG. 3, shown in a Zeiss Auriga scanning electron microscope, in 400-fold magnification.
  • a three-dimensional microscopic view of a section of a coated stent according to the invention shown in the scanning electron microscope, in 103-fold magnification; Definition of analyzed stent sections after dilatation;
  • FIG. 1 an uncoated carrier or a container stent 6 can be seen, as it is present after the electropolishing.
  • the grid of the illustrated stent 6 has a plurality of support rings 8 connected to one another at different locations, wherein the support rings 8 are each formed by a meander-shaped filament winding into a plurality of curvature arcs.
  • at least one curve bend of a first support ring and a curve bend of an adjacent second support ring overlap laterally, wherein the connection point is formed in the overlapping region.
  • the section of the coated vessel stent shown in FIG. 4 of FIG. 3 shows a coherent coating 12 with only minor damage 13.
  • the morphology of the SiO 2 layer 12 is strongly determined by the roughness of the underlying substrate surface 10. If this is rough, inhomogeneous layer structures also result.
  • electrochemical impedance spectroscopy EIS can be used to evaluate the quality of the coatings and to distinguish fine differences in dilation behavior.
  • the dilation behavior was tested by varying the stents on a balloon catheter, ie by 0%, 25%, 50%, 75% and 100%, expanded and analyzed by scanning electron microscope (Zeiss, Gemini 1530FE). Due to its special design, the deformation of the stents according to the invention occurs exclusively at the connection points (T-pieces) and the "deflections.” Accordingly, the damage 13 of the coating 12 also takes place primarily at these heavily stressed points (see FIG 6 shows a section of a stent surface 10 near the cut surface with a view of the cross section of the layer, the layer thickness being approximately 600-800 nm.
  • a liquid heating means deionized water
  • the entire cavity gap is equipped with guide means (not shown) for the heating means in order to guide the heating means so as to achieve a homogeneous temperature distribution over the inner wall 1b.
  • guide means (not shown) for the heating means in order to guide the heating means so as to achieve a homogeneous temperature distribution over the inner wall 1b.
  • This also applies to the temperature-controlled, double-walled closure lid ld, which provides access to the use and removal of the stents.
  • the annular shower 2 is embedded for the carrier gas stream with the precursor HMDSO.
  • feed temperature TL 45 ° C.
  • the precursor stream is 4 sccm during the coating.
  • the holes 2c are arranged in the present embodiment by about 40 mm lower than the inlet nozzle 3 for the process gas flow.
  • stents 6 are positioned on the electrically insulating support members 5b on the support, the stent support plate 5a.
  • the chemically resistant and stainless steel plate lies on the cylindrical counter electrode, which has a diameter of 145 mm.
  • This electrode 4 is electrically insulating and vacuum-tightly connected to the shield 4c and held therein in the process chamber, i. in the present case approx. 150 mm below the holes 2c.
  • coolant eg deionized water
  • RF High voltage 13.56 MHz
  • the process chamber is evacuated by connecting a suitable, typically multi-stage vacuum pump to the intake 7.
  • the system used here consists in the core of a cylindrical vacuum chamber, the reactor with a volume of about 8.3 1, the proportion of the so-called "stent chamber” only approx
  • the carrier gas (0 2 ) of the laminating agent (HMDSO) required for the reaction is fed in at the top of the system and flows laminarly at the selected reactor pressure of 0.14 mbar to those in the lower part of the stent chamber
  • the counter electrode with the stent support plate is provided with an electrical supply for operating a radio frequency (RF) discharge.
  • RF radio frequency
  • a gas flow rate (flow rate) of 100 sccm for oxygen was used for the purification (standard volume flow in standard cubic centimeters per minute (sccm)), with a plasma power of 200 W and a cleaning time of 2 x 10 sec
  • other gases such as argon (Ar), ammonia gas (NH 3 ), hydrogen (H 2 ) or ethyne (C 2 H 2) could also be considered for purification.
  • a stainless, non-magnetic stent-holding plate 5a eg, a steel plate provided with support members 5b (eg, pins), see Fig. 8
  • the steel plate 5a has a diameter of 140mm simultaneous coating of several stents 6 twelve 5 mm high pins 5b 11 (preferably metal pins) of 1.5 mm diameter on the steel plate 5 a are mounted.
  • the HMDSO used (Sigma-Aldrich, CAS N ° 107-46-0) has a boiling point of 101 ° C, a melting point of -59 ° C at a density of 0.764 g / ml at 20 ° C.
  • the gaseous oxygen used (PanGas AG, 0 2 5.0) has a purity of 99.99999%.

Landscapes

  • Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • General Health & Medical Sciences (AREA)
  • Vascular Medicine (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Veterinary Medicine (AREA)
  • Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Inorganic Chemistry (AREA)
  • Surgery (AREA)
  • Epidemiology (AREA)
  • Chemical & Material Sciences (AREA)
  • Cardiology (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Transplantation (AREA)
  • Media Introduction/Drainage Providing Device (AREA)
  • Materials For Medical Uses (AREA)
  • Prostheses (AREA)

Abstract

L'invention concerne un enrobage (12) pour implant médical, en particulier pour un stent vasculaire (6) comprenant du dioxyde de silicium, l'épaisseur de l'enrobage atteignant 40 à 150 nm. L'invention concerne également un procédé pour fabriquer ce type d'enrobage, un implant médical enrobé et le procédé de fabrication de ce dernier.
EP13734758.9A 2012-08-06 2013-07-08 Stent enrobé Withdrawn EP2879730A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH01284/12A CH706803A1 (de) 2012-08-06 2012-08-06 Beschichteter Stent.
PCT/EP2013/064341 WO2014023495A1 (fr) 2012-08-06 2013-07-08 Stent enrobé

Publications (1)

Publication Number Publication Date
EP2879730A1 true EP2879730A1 (fr) 2015-06-10

Family

ID=46982305

Family Applications (1)

Application Number Title Priority Date Filing Date
EP13734758.9A Withdrawn EP2879730A1 (fr) 2012-08-06 2013-07-08 Stent enrobé

Country Status (8)

Country Link
US (1) US20150196691A1 (fr)
EP (1) EP2879730A1 (fr)
CN (1) CN104519923B (fr)
AU (1) AU2013301795B2 (fr)
CH (1) CH706803A1 (fr)
IN (1) IN2015KN00212A (fr)
SG (1) SG11201500854RA (fr)
WO (1) WO2014023495A1 (fr)

Families Citing this family (7)

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Publication number Priority date Publication date Assignee Title
CN106456847A (zh) * 2014-07-22 2017-02-22 百多力股份公司 可生物降解的金属支架和方法
CN107811726B (zh) * 2016-09-13 2020-09-25 先健科技(深圳)有限公司 覆膜支架
WO2018131476A1 (fr) 2017-01-10 2018-07-19 不二ライトメタル株式会社 Alliage de magnésium
CN110234366B (zh) * 2017-01-30 2021-11-02 株式会社日本医疗机器技研 高功能生物可吸收支架
CN111801435A (zh) 2018-07-09 2020-10-20 株式会社日本医疗机器技研 镁合金
USD1009108S1 (en) 2020-09-21 2023-12-26 Kyocera Unimerco Tooling A/S Drill
CN113694262A (zh) * 2021-08-26 2021-11-26 苏州脉悦医疗科技有限公司 一种生物可吸收的镁合金支架及其制备方法

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DE60141335D1 (de) * 2000-07-28 2010-04-01 Blue Medical Devices B V Intravaskulärer stent mit expandierbarer beschichtung
DE10230720A1 (de) 2002-07-08 2004-02-12 Tinox Ag I.Ins. Implantat
DE10353756A1 (de) * 2003-11-17 2005-06-30 Bio-Gate Bioinnovative Materials Gmbh Schichtmaterial
DE102005024913A1 (de) * 2005-05-31 2006-12-14 Axetis Ag Gefäßstents
ATE416736T1 (de) 2005-08-10 2008-12-15 Axetis Ag Rohrförmige stützprothese mit sich seitlich überlappenden krümmungsbögen
US20080033522A1 (en) * 2006-08-03 2008-02-07 Med Institute, Inc. Implantable Medical Device with Particulate Coating

Non-Patent Citations (2)

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Title
None *
See also references of WO2014023495A1 *

Also Published As

Publication number Publication date
CN104519923A (zh) 2015-04-15
SG11201500854RA (en) 2015-04-29
US20150196691A1 (en) 2015-07-16
WO2014023495A1 (fr) 2014-02-13
CH706803A1 (de) 2014-02-14
AU2013301795A1 (en) 2015-02-26
IN2015KN00212A (fr) 2015-06-12
CN104519923B (zh) 2017-02-01
AU2013301795B2 (en) 2015-07-09

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