Layered stent-graft and methods of making the same

• US 6,752,826 B2
• Filed: 12/14/2001
• Issued: 06/22/2004
• Est. Priority Date: 12/14/2001
• Status: Expired due to Term

• Current Assignee: Thoratec LLC
• Original Assignee: Thoratec LLC
• Inventors: Christoforou, Christofer T., Holloway, Ken A.
• Primary Examiner(s): Thaler, Michael H.
• Application Number:
  US10/017,693
• Publication Number:
  US 20030114917A1
• Time in Patent Office: 921 Days
• Field of Search: 623/1.13, 623/1.14, 623/1.32, 623/1.33, 623/1.44
• US Class Current: 623/1.13
• CPC Class Codes: A61F 2/07 Stent-grafts
• 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 2002/065 Y-shaped blood vessels
• CPC Class Codes: A61F 2002/072 Encapsulated stents, e.g. wire or whole stent embedded in lining
• CPC Class Codes: A61F 2250/0067 Means for introducing or releasing pharmaceutical products into the body

Abstract

A stent-graft made of at least three concentric layers is disclosed. The inner and outer layers can be porous. The middle layer can be non-porous and encompasses a stent.

Claims

1. A stent-graft comprising:

an intraluminal implantable body configured for percutaneous intraluminal delivery into a vessel, the intraluminal implantable body comprising a porous first layer having an outer surface, the entire longitudinal length of the outer surface of the porous first layer is adapted to make contact with tissue of a vessel wall;

a non-porous layer attached to the porous first layer;

a self expandable. balloon expandable or combination of self expandable and balloon expandable stent, for allowing the stent-graft to expand to a suitable diameter to compress the porous first layer against a vessel wall such that the stent is mechanically supporting the vessel wall, encapsulated by the non-porous layer; and

a porous second layer attached to the non-porous layer having the stent, the porous second layer having an inner surface that is adapted to make contact with bodily fluids that flow through a longitudinal bore of the stent-graft wherein the stent-graft includes (i) a compressed configuration that allows the stent-graft to be delivered percutaneouly and intraluminally into a vessel by a catheter and/or a guide wire and maneuvered along a vascular network to a delivery site and (ii) expanded configuration, substantially greater in outer diameter than the compressed configuration that allows the stent-graft to be secured inside of a vessel, and wherein the thickness of the combination of the layers is of a suitable size that does not adversely affect the flow of fluid through the vessel.

2. The stent-graft of claim 1, wherein the porous first layer has a void-to-volume ratio of about 40% to about 90%.

3. The stent-graft of claim 1, wherein the porous first layer has a void-to-volume ratio of about 70% to about 80%.

4. The stent-graft of claim 1, wherein the non-porous layer has a void-to-volume ratio of about less than 5%.

5. The stent-graft of claim 1, wherein the non-porous layer has a void-to-volume ratio of about less than 1%.

6. The stent-graft of claim 1, wherein the porous second layer has a void-to-volume ratio of about 40% to about 90%.

7. The stent-graft of claim 1, wherein the porous second layer has a void-to-volume ratio of about 65% to about 80%.

8. The stent-graft of claim 1, wherein pores of the porous first and second layers have an average pore diameter of about 1 micron to about 400 microns.

9. The stent-graft of claim 1, wherein the stent comprises a plurality of interconnected struts separated by gaps.

10. The stent-graft of claim 1, wherein the stent comprises a plurality of rings separated at a distance from one another.

11. The stent-graft of claim 1, wherein the porous first or second layer comprises a plurality of sub-layers, each sub-layer having a different porosity.

12. The stent-graft of claim 1, wherein the porous first layer is made from a hydrogel.

13. The stent-graft of claim 1, wherein the porous first layer is bioabsorbable or biodegradable so as to absorb or degrade in a lumen after a duration of time.

14. The stent-graft of claim 1, wherein the porous second layer is bioabsorbable or biodegradable so as to absorb or degrade in a lumen after a duration of time.

15. The stent-graft of claim 1, wherein the stent-graft is capable of folding in half along a longitudinal axis of the stent-graft.

16. The stent-graft of claim 1, wherein the stent-graft is capable of folding over at least three times along a longitudinal axis of the stent-graft.

17. The stent-graft of claim 1, wherein the outer surface of the porous first layer is lubricious.

18. The stent-graft of claim 1, wherein the outer surface of the porous first layer is not capable of sticking to itself when the stent-graft is crimped to a smaller diameter or folded along a longitudinal axis of the stent-graft.

19. The stent-graft of claim 1, wherein the pores of the second layer contain thromboresistant chemicals.

20. The stent-graft of claim 1, wherein the porous first layer includes an anionic hydrogel.

21. The stent-graft of claim 1, wherein the porous first layer includes a chemical that inhibits cell growth or is made from a material that inhibits cell growth.

22. The stent-graft of claim 1, wherein the non-porous layer does not include a seam at the junction where the stent is encapsulated in the non-porous layer.

23. The stent-graft of claim 1, wherein the stent-graft includes a bifurcated portion.

24. The stent-graft of claim 1, wherein pores of the porous first and second layers have an average pore diameter of about 150 micron to about 400 microns.

25. The stent-graft of claim 1, wherein the porous first layer allows for intimal growth within the first layer so as to anchor the stent-graft within a vessel lumen.

26. The stent-graft of claim 1, wherein the porous first layer has a thickness of about 50 microns to about 75 microns.

27. The stent-graft of claim 1, wherein the porous second layer has a thickness of about 50 microns to about 75 microns.

28. The stent-graft of claim 1, wherein the porous second layer is made from a hydrogel.

29. A method of manufacturing a intraluminal stent-graft comprising:

(a) forming a porous first layer on a mandrel, the porous first layer being the inner most layer of the intraluminal stent-graft such that an inner surface of the porous first layer is configured to be exposed to bodily fluids that travel through a longitudinal bore of the intraluminal stent-graft;

(b) forming a non-porous second layer on the porous first layer;

(c) positioning a stent on the non-porous second layer;

(d) increasing the thickness of the non-porous second layer to substantially or completely encapsulate the stent in the non-porous second layer; and

(e) forming a porous third layer on the non-porous second layer, the porous third layer being the outermost layer of the intraluminal stent-graft and configured to make contact with a wall of the vessel, wherein the stent-graft is of a suitable dimension to allow for percutaneous insertion of the stent-graft within a lumen of a patient, wherein the stent-graft includes a compressed configuration that allows the entire length of the stent-graft to be delivered percutaneouly into a vessel by a catheter and/or a guide wire and a deployed, expanded configuration, substantially greater in diameter than the compressed configuration, that allows the stent-graft to be implanted within a vessel and wherein the thickness of the combination of the layers is of a suitable size that does not adversely affect the flow of fluid through the vessel.

30. The method of claim 29, wherein the act of forming the porous first layer comprises applying a composition comprising a solvent, a polymer dissolved in the solvent, and water-soluble particles added thereto to the mandrel and removing the solvent and the water-soluble particles from the polymer.

31. The method of claim 30, wherein the water-soluble particles are removed subsequent to removal of the solvent.

32. The method of claim 29, wherein the act of forming the third layer comprises applying a composition comprising a solvent, a polymer dissolved in the solvent, and water-soluble particles added thereto to the second layer and removing the solvent and water-soluble particles from the polymer.

33. The method of claim 32, wherein the water-soluble particles are removed subsequent to removal of the solvent.

34. The method of claim 29, wherein the porous first and third layers have a void-to-volume ratio of about 40% to about 90%.

35. The method of claim 29, wherein the second layer has a void-to-volume ratio of less than about 5%.

36. The method of claim 29, wherein the stent comprises a plurality of interconnected struts.

37. The method of claim 29, wherein the stent comprises a plurality of rings separated at a distance from one another.

38. The method of claim 29, wherein the second layer does not include any gapped regions about the area where the second layer is in contact with the surfaces of the stent.

39. The method of claim 29, wherein the acts of (a) and (b) comprise:

(a) applying a first composition comprising a first polymer and a first solvent to the mandrel and removing most of the first solvent from the first composition to solidify the first polymer on the mandrel but allowing the surface of the first polymer to be in a semi-sold state;

(b) applying a second composition comprising a second polymer and a second solvent to the first polymer and removing the first and second solvents to form the first layer and the second layer attached to the first layer.

40. The method of claim 29, wherein the acts of (b) through (e) comprise:

(a) applying a first composition comprising a first polymer and a first solvent to the first layer and removing essentially all of the first solvent from the first composition to solidify the first polymer for the second layer;

(b) positioning the stent on the second layer;

(c) reapplying the first composition to the second layer and the stent and removing the first solvent from the first composition to increase the thickness of the second layer;

(d) repeating act (c) if needed until the stent is substantially or completely encapsulated by the second layer; and

(e) applying a second composition comprising a second polymer and a second solvent to the second layer to form the third layer.

41. The method of claim 40, wherein the second composition is applied to the second layer having a semi-solid surface.