Layered stent-graft and methods of making the same

• US 20030114917A1
• Filed: 12/14/2001
• Published: 06/19/2003
• Est. Priority Date: 12/14/2001
• Status: Active Grant

• Current Assignee: Thoratec LLC
• Original Assignee: Thoratec LLC
• Inventors: Christoforou, Christofer T., Holloway, Ken A.
• Granted Patent: US 6,752,826 B2
• Time in Patent Office: Days
• 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:

a porous first layer for making contact with tissue of a vessel wall;

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

a frame encapsulated by the non-porous layer; and

a porous second layer, wherein the non-porous layer is between the porous first layer and the porous second layer.

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 frame comprises a plurality of interconnected struts separated by gaps.

10. The stent-graft of claim 1, wherein the frame 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, wherein each sub-layer has a different porosity.

12. A method of manufacturing a stent-graft comprising:

(a) forming a porous first layer on a mandrel;

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

(c) positioning a frame on the second layer;

(d) increasing the thickness of the second layer to substantially or completely encapsulate the frame in the second layer; and

(e) forming a porous third layer on the second layer.

13. The method of claim 12, 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.

14. The method of claim 12, 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.

15. The method of claim 12, wherein the porous first and third layers have a void-to-volume ratio of about 40% to about 90%.

16. The method of claim 12, wherein the second layer has a void-to-volume ration of less than about 5%.

17. The method of claim 12, wherein the frame comprises a plurality of interconnected struts.

18. The method of claim 12, wherein the frame comprises a plurality of rings separated at a distance form one another.

19. The method of claim 12, wherein the second layer does not include any gaped regions about the area where the second layer is in contact with the surfaces of the frame.

20. The method of claim 12, wherein the acts of (a) and (b) comprise:

(a) applying the first composition comprising a first polymer and a first solvent to the mandrel and removing essentially most of the first solvent from the 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 the 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.

21. The method of claim 12, 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 composition to solidify the first polymer;

(b) positioning the frame on the second layer;

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

(d) repeating act (c) if needed until the scaffolding structure 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.