Stents made of biodegradable and non-biodegradable materials

Abstract

A stent comprising a plurality of annular elements aligned in the longitudinal direction of extension of the stent and selectively expandable between a radially-contracted condition and a radially-expanded condition as well as a series of connecting elements that extend in the longitudinal direction of extension of the stent to connect the annular elements. The annular elements and the connecting elements are made, respectively, of non-biodegradable material and of biodegradable material. The structure of the stent thus comprises a part of non-biodegradable material, destined to remain long-term at the site of implantation, and a part of biodegradable material, destined to disappear within a longer or shorter period after implantation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of non-limiting examples, with reference to the attached drawings.

FIGS. 1 and 2 show, in diagram form, the basic part of the stent described here.

FIGS. 3, 4, and 5 correspond to three possible embodiments of the stent described here.

Claims

1. A stent comprising a tubular structure selectively expandable between a radially-contracted condition and a radially-expanded condition, said tubular structure comprising a part of non-biodegradable material and a part of biodegradable material.

2. A stent according to claim 1, wherein said tubular structure comprises: a plurality of annular elements aligned along the longitudinal direction of extension of the stent, said annular elements being selectively expandable between a radially-contracted condition and a radially-expanded condition, anda series of connecting elements that extend in the longitudinal direction of extension of the stent to connect said annular elements, andwherein said annular elements and said connecting elements are made, respectively, of non-biodegradable material and of biodegradable material.

3. A stent according to claim 2, wherein said annular elements are made of metallic material.

4. A stent according to claim 3, wherein said metallic material is selected from the group consisting of steel and a cobalt-chromium alloy.

5. A stent according to claim 2, wherein said annular elements extend following a looped trajectory.

6. A stent according to claim 2, wherein said annular elements extend following a sinusoidal trajectory.

7. A stent according to claim 6, wherein said plurality of adjacent annular elements extend following a sinusoidal trajectory in phase opposition one to the other.

8. A stent according to claim 2, wherein said plurality of annular elements are connected by longitudinal connecting elements of non-biodegradable material.

9. A stent according to claim 8, wherein said longitudinal connecting elements of non-biodegradable material are substantially non-extensible in the longitudinal direction of the stent.

10. A stent according to claim 8, wherein said longitudinal connecting elements of non-biodegradable material are present, connecting between pairs of said adjacent annular elements, in a lower number than said connecting elements of biodegradable material.

11. A stent according to claim 10, wherein said longitudinal connecting elements of non-biodegradable material, connecting pairs of said annular elements adjacent one to the next, are present to an extent not above 25% of said connecting elements of biodegradable material.

12. A stent according to claim 11, wherein said longitudinal connecting elements of non-biodegradable material, connecting pairs of said annular elements adjacent one to the next, are present to an extent not above 20% of said connecting elements of biodegradable material.

13. A stent according to claim 12, wherein said longitudinal connecting elements of non-biodegradable material, connecting pairs of said annular elements adjacent one to the next, are present to an extent not above 10% of said connecting elements of biodegradable material.

14. A stent according to claim 1, wherein said biodegradable material is a polymer.

15. A stent according to claim 1, wherein said biodegradable material is selected from the group consisting of polylactic acid; poly-ε-caprolactone; polyorthoesters; polyanhydrides; poly-3-hydroxybutyrate; polyaminoacids; polyglycine; polyphosphazenes; polyvinyl alcohol; low molecular weight polyacrylates; and co-polymers of the above.

16. A stent according to claim 1, wherein said biodegradable material is selected from the group consisting of iron and magnesium.

17. A stent according to claim 1, wherein said part of biodegradable material includes connecting elements of biodegradable material extending following a substantially straight trajectory in the longitudinal direction of extension of the stent.

18. A stent according to claim 1, wherein said part of biodegradable material includes connecting elements of biodegradable material that extend following trajectories that are substantially looped in shape, with loops oriented transversally to the longitudinal direction of extension of the stent.

19. A stent according to claim 18, wherein said looped trajectories are sinusoidal trajectories.

20. A stent according to claim 1, wherein said part of biodegradable material includes connecting elements of biodegradable material extending over the entire length of the stent.

21. A stent according to claim 1, wherein said part of biodegradable material includes connecting elements of biodegradable material extending over a part of the length of the stent.

22. A stent according to claim 1, wherein the stent comprises anchorage points between said part of biodegradable material and said part of non-biodegradable material.

23. A stent according to claim 22, wherein said anchorage points are welding spots between said non-biodegradable material and said biodegradable material.

24. A stent according to claim 22, wherein said anchorage points are adhesive points between said non-biodegradable material and said biodegradable material.

25. A stent according to claim 22, wherein said anchorage points are interweaving points between said longitudinal connecting elements of biodegradable material and said annular elements.

26. A stent according to claim 1, wherein said part of biodegradable material forms a network structure that fits over said part of non-biodegradable material.

27. A stent according to claim 1, wherein said part of biodegradable material carries a drug.

28. A stent according to claim 27, wherein said drug is an agent antagonistic to restenosis.

29. A stent according to claim 28, wherein said agent antagonistic to restenosis is selected from the group consisting of paclitaxel, rapamycin, micophenolic acid, rapamycin, tacrolimus, cyclosporin, and corticosteroids.

30. A stent according to claim 27, wherein said part of biodegradable material includes a plurality of connecting elements of biodegradable material that carry different drugs one from the other.

31. A stent according to claim 27, wherein said part of biodegradable material includes a plurality of connecting elements of biodegradable material that carry different dosages of the same drug.

32. A stent according to claim 27, wherein said part of biodegradable material includes at least one connecting element of biodegradable material that carries different drugs along the longitudinal development of the stent.

33. A stent according to claim 27, wherein said part of biodegradable material includes at least one element of biodegradable material that carries different dosages of the same drug along the longitudinal development of the stent.

34. A stent according to claim 27, wherein said drug is mixed with said biodegradable material.

35. A stent according to claim 27, wherein said drug is applied onto said biodegradable material.

36. A stent according to claim 35, wherein said biodegradable material is in the form of fibers and said drug is co-extruded with said fibers.

37. A stent according to claim 27, wherein said drug is disposed on said part of biodegradable material in the form of nanoparticles.

38. A stent according to claim 1, wherein the stent includes a coating of biocompatible carbonaceous material applied on said part of non-biodegradable material.

39. A stent according to claim 38, wherein said part of biodegradable material does not comprise said coating of biocompatible carbonaceous material.