HYBRID STENT AND METHOD OF MAKING

• US 20080188924A1
• Filed: 08/01/2007
• Published: 08/07/2008
• Est. Priority Date: 04/01/2002
• Status: Active Grant

• Current Assignee: Advanced Cardiovascular Systems Incorporated
• Original Assignee: Advanced Cardiovascular Systems Incorporated
• Inventors: Prabhu, Santosh
• Granted Patent: US 7,959,999 B2
• Time in Patent Office: Days
• US Class Current: 623/1.16
• CPC Class Codes: A61F 2/04 Hollow or tubular parts of organs, e.g. bladders, tracheae, bronchi or bile ducts A61F2/18, A61F2/20 take precedence; devices, other than stent-grafts, providing patency to, or preventing collapsing of, tubular structures of the body other than stent-grafts, e.g. stents A61F2/82; instruments specially adapted for placement or removal of stents or stent-grafts A61F2/95
• CPC Class Codes: A61F 2/07 Stent-grafts
• CPC Class Codes: A61F 2/82 Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents stent-grafts for tubular structures of the body other than blood vessels A61F2/04; stent-grafts for blood vessels A61F2/07; instruments specially adapted for placement or removal of stents or stent-grafts A61F2/95; for closing wounds, or holding wounds closed A61B17/04 - A61B17/115; dilators A61M29/00
• CPC Class Codes: A61F 2/852 Two or more distinct overlapping stents
• CPC Class Codes: A61F 2/89 the wire-like elements comprising two or more adjacent rings flexibly connected by separate members
• CPC Class Codes: A61F 2/91 made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes
• CPC Class Codes: A61F 2/915 with bands having a meander structure, adjacent bands being connected to each other
• CPC Class Codes: A61F 2002/072 Encapsulated stents, e.g. wire or whole stent embedded in lining
• CPC Class Codes: A61F 2002/91558 connected peak to peak
• CPC Class Codes: A61F 2210/0076 multilayered, e.g. laminated structures
• CPC Class Codes: A61F 2230/0013 Horseshoe-shaped, e.g. crescent-shaped, C-shaped, U-shaped
• CPC Class Codes: A61F 2230/0054 V-shaped
• CPC Class Codes: A61F 2230/0069 cylindrical
• CPC Class Codes: A61F 2240/001 Designing or manufacturing processes
• CPC Class Codes: A61F 2250/0032 differing in radiographic density
• CPC Class Codes: A61F 2250/0063 Nested prosthetic parts
• CPC Class Codes: A61F 2250/0067 Means for introducing or releasing pharmaceutical products into the body
• CPC Class Codes: A61K 31/727 Heparin; Heparan
• CPC Class Codes: A61L 2300/236 Glycosaminoglycans, e.g. heparin, hyaluronic acid, chondroitin
• CPC Class Codes: A61L 2300/606 Coatings
• CPC Class Codes: A61L 31/022 : Metals or alloys
• CPC Class Codes: A61L 31/048 : obtained by reactions only involving carbon-to-carbon unsaturated bonds A61L31/041 takes precedence
• CPC Class Codes: A61L 31/10 : Macromolecular materials
• CPC Class Codes: A61L 31/16 : Biologically active materials, e.g. therapeutic substances A61L31/047 takes precedence
• CPC Class Codes: A61L 31/18 : Materials at least partially X-ray or laser opaque
• CPC Class Codes: B23K 2103/42 : Plastics B23K2103/16 takes precedence
• CPC Class Codes: B23K 2103/50 : Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 2103/54 : Glass
• CPC Class Codes: B23K 26/38 : by boring or cutting
• CPC Class Codes: B23K 26/402 : involving non-metallic material, e.g. isolators
• CPC Class Codes: B29C 41/08 : Coating a former, core or other substrate by spraying or fluidisation, e.g. spraying powder spray-up of reinforcing fibres B29C70/305
• CPC Class Codes: B29C 41/14 : Dipping a core B29C41/10 takes precedence
• CPC Class Codes: B29C 41/20 : incorporating preformed parts or layers, e.g. moulding inserts or for coating articles
• CPC Class Codes: B29C 41/22 : Making multilayered or multicoloured articles
• CPC Class Codes: B29C 65/16 : Laser beams
• CPC Class Codes: B29C 65/68 : using auxiliary shrinkable elements
• CPC Class Codes: B29K 2027/18 : PTFE, i.e. polytetrafluorethene , e.g. ePTFE, i.e. expanded polytetrafluorethene
• CPC Class Codes: B29L 2031/7534 : Cardiovascular protheses
• CPC Class Codes: Y10T 29/49906 : Metal deforming with nonmetallic bonding
• CPC Class Codes: Y10T 428/139 : Open-ended, self-supporting conduit, cylinder, or tube-type article
• CPC Class Codes: Y10T 428/1393 : Multilayer [continuous layer]

Abstract

A stent is formed by encasing or encapsulating metallic rings in an inner polymeric layer and an outer polymeric layer. At least one polymer link connects adjacent metallic rings. The stent is drug loaded with one or more therapeutic agent or drug, for example, to reduce the likelihood of the development of restenosis in the coronary arteries. The inner and outer polymeric materials can be of the same polymer or different polymer to achieve different results, such as enhancing flexibility and providing a stent that is visible under MRI, computer tomography and x-ray fluoroscopy.

Claims

1. A stent, comprising:

a plurality of metallic rings aligned along a stent longitudinal axis;

an outer layer of a first polymeric material covering an outer surface of the metallic rings;

an inner layer of a second polymeric material covering an inner surface of the metallic rings; and

at least one link connecting adjacent metallic rings, the links being formed by the outer layer and the inner layer.

2. The stent of claim 1, wherein the first polymeric material is EVOH.

3. The stent of claim 1, wherein the second polymeric material is PEEK.

4. The stent of claim 3, wherein the PEEK is radiopaque.

5. The stent of claim 2, wherein the EVOH is radiopaque.

6. The stent of claim 1, wherein the first and second polymeric materials are taken from the group of polymers consisting of polyetheretherketone (PEEK), ethyl vinyl alcohol (EVOH), polyetherketone, polymethylmethacrylate, polycarbonate, polyphenylenesulfide, polyphenylene, polyvinylfluoride, polyvinylidene fluoride, polypropylene, polyethylene, poly(vinylidene fluoride-co-hexafluoropropylene), poly(ethylene-co-hexafluoropropylene), poly(tetrafluoroethyelene-co-hexafluoropropylene), poly(tetrafluoroethyelene-co-ethylene), polyethyleneterephthalate, polyimides, polyetherimide, ePTFE, polyurethanes, polyetherurethanes, polyesterurethanes, silicone, thermoplastic elastomer, polyether-amide thermoplastic elastomer, fluoroelastomers, fluorosilicone elastomer, styrene-butadiene-styrene rubber, styrene-isoprene-styrene rubber, polybutadiene, polyisoprene, neoprene, ethylene-propylene elastomer, chlorosulfonated polyethylene elastomer, butyl rubber, polysulfide elastomer, polyacrylate elastomer, nitrile rubber, a family of elastomers composed of styrene, ethylene, propylene, aliphatic polycarbonate polyurethane, polymers augmented with antioxidants, polymers augmented with image enhancing materials, polymers having a proton (H+) core, butadiene and isoprene and polyester thermoplastic elastomer and a di-block co-polymer of PET and caprolactone.

7. The stent of claim 1, wherein the metallic rings are formed of a metal alloy taken from the group of metal alloys consisting of stainless steel, titanium, tantalum, nickel-titanium, cobalt-chromium, and tungsten.

8. The stent of claim 1, wherein one or both of the first and second polymeric materials are loaded with a therapeutic drug.

9. The stent of claim 8, wherein the therapeutic drug is taken from the group of drugs including one or more of everolimus, rapamycin, actinomycin D (ActD), or derivatives and analogs thereof;

synonyms of actinopmycin D including dactinomycin, actinomycin IV, actinomycin 11, actinomycin X1, and actinomycin C1;

antiproliferative substances including antineoplastic, antinflammatory, antiplatelet, anticoagulant, antifibrin, antithomobin, antimitotic, antibiotic, antioxidant substances, taxol (paclitaxel and docetaxel), anticoagulants, antifibrins, sodium heparin, low molecular weight heparin, hirudin, argatroban, forskolin, vapiprost, prostacyclin and prostacyclin analogs, dextran, D-phe-pro-arg-chloromethylketone (synthetic antithrombin), dipyridamole, glycoprotein, 11b/111a platelet membrane receptor antagonist, recombinant hirudin, thrombin inhibitor methotrexate, azathioprine, vincristine, vinblastine, fluorouracil, adriamycin, mutamycin;

angiopeptin, angiotensin converting enzyme inhibitors;

calcium channel blockers;

colchicine fibroblast growth factor (FGF) antagonists;

fish oil (omega 3-fatty acid);

histamine antagonist;

monoclonal antibodies (such as PDGF receptors);

nitroprusside;

phosphodiesterase inhibitors;

prostaglandin inhibitor (a PDGF antagonist);

serotonin blockers;

steroids;

thioprotease inhibitors;

triazolopyrimidine (a PDGF antagonist); and

nitric oxide.

10. The stent of claim 1, wherein a radiopaque marker is positioned between the first polymeric material and the second polymeric material.

11. The stent of claim 1, wherein the outer layer of the first polymeric material has a thickness in the range of 0.001 mm to 2.5 mm.

12. The stent of claim 11, wherein the outer layer has a uniform thickness.

13. The stent of claim 11, wherein the outer layer has a variable thickness.

14. The stent of claim 1, wherein the inner layer of the second polymeric material has a thickness in the range of 0.001 mm to 2.5 mm.

15. The stent of claim 14, wherein the inner layer has a uniform thickness.

16. The stent of claim 14, wherein the inner layer has a variable thickness.

17. The stent of claim 1, wherein the metallic rings have an undulating pattern.

18. The stent of claim 17, wherein the undulating pattern includes U-shaped elements.

19. The stent of claim 1, wherein the stent is configured so that it is visible under any of x-ray fluoroscopy, computer tomography, or MRI.

20. The stent of claim 1, wherein a cavity is formed between the first polymeric material and the second polymeric material so that a therapeutic drug can be releasably contained within the cavity.

21. The stent of claim 1, wherein the metallic rings are formed of struts, the struts having a substantially uniform radial thickness.

22. The stent of claim 1, wherein the metallic rings are formed of struts, the struts having a variable radial thickness.

23. The stent of claim 1, wherein the first polymeric material is a shape memory polymer.

24. The stent of claim 23, wherein the shape memory polymer includes the family of polymers oligo (e-caprolactone) dimethacrylate combined with n-butyl acrylate.

25. A method of making a hybrid stent, comprising:

laser cutting a tubular member to form a pattern of metallic rings;

mounting a first polymeric tube onto mandrel and positioning the metallic rings over the polymeric tube;

mounting a second polymeric tube over the metallic rings and the first polymeric tube;

fusing the first polymeric tube to the second polymeric tube with the metallic rings therebetween; and

removing the fused first polymeric tube and the second polymeric tube from the mandrel.

26. The method of claim 25, wherein prior to fusing the polymeric tubes, positioning a shrink tubing over the second polymeric tubing and applying heat to the shrink tubing so that the shrink tubing tightly compresses onto the second polymeric tube, the heat being sufficient to fuse at least a portion of the first polymeric tube to the second polymeric tube.

27. The method of claim 26, wherein the heat is provided by a laser.

28. The method of claim 25, wherein an adhesive is applied to an outer surface of the first polymeric tube prior to mounting the second polymeric tube to assist in fusing the tubes together.

29. The method of claim 28, wherein the adhesive is heat activated.

30. The method of claim 25, wherein after the stent is removed from the mandrel, forming a pattern by removing portions of the fused first and second polymeric tubes.

31. The method of claim 30, wherein the portions of the fused first and second polymeric tubes are removed by laser ablation.

32. The method of claim 31, wherein links for connecting the metallic rings are formed by laser ablation of the fused first and second polymeric tubes.

33. The method of claim 25, wherein a therapeutic drug is loaded into either or both of the first and second polymeric tubes.

34. The method of claim 32, wherein the first and second polymeric tubes are drug loaded after laser ablation.

35. A method of making a hybrid stent, comprising:

coating a mandrel with a first polymer to form a first polymeric tube;

mounting a plurality of metallic rings over the first polymeric tube;

applying a second polymeric material over the metallic rings and the first polymeric tube to form the stent; and

removing the stent from the mandrel.

36. The method of claim 35, wherein the first polymeric tube is formed by dip-coating the mandrel in a first polymeric material.

37. The method of claim 35, wherein the second polymeric material is applied to the rings and the first polymeric tube by dip-coating.

38. The method of claim 35, wherein the second polymeric material is sprayed onto the metallic rings and the first polymeric tube.

39. The method of claim 35, wherein portions of the first and second polymeric materials are removed by laser ablation.

40. The method of claim 39, wherein links for connecting the metallic rings are formed by laser ablation of the first and second polymeric materials.

41. The method of claim 35, wherein a therapeutic drug is loaded into either or both of the first and second polymeric materials.