Bioerodible endoprostheses and methods of making the same

• US 8,057,534 B2
• Filed: 09/14/2007
• Issued: 11/15/2011
• Est. Priority Date: 09/15/2006
• Status: Active Grant

• Current Assignee: Boston Scientific Scimed (Boston Scientific Corporation)
• Original Assignee: Boston Scientific Scimed (Boston Scientific Corporation)
• Inventors: Merdan, Ken, Shedlov, Matt, Boismier, Dennis A., O'Brien, Barry, Girton, Timothy S., Larsen, Steven R.
• Primary Examiner(s): Isabella; David
• Assistant Examiner(s): Woznicki; Jacqueline
• Application Number:
  US11/855,516
• Publication Number:
  US 20080082162A1
• Time in Patent Office: 1,523 Days
• Field of Search: 623/1.38
• US Class Current: 623/1.38
• CPC Class Codes: A61F 2/06 Blood vessels
• 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 2002/30032 differing in absorbability or resorbability, i.e. in absorption or resorption time
• CPC Class Codes: A61F 2002/30051 differing in corrosion resistance
• CPC Class Codes: A61F 2002/30062 (bio)absorbable, biodegradable, bioerodable, (bio)resorbable, resorptive
• CPC Class Codes: A61F 2002/3011 Cross-sections or two-dimensional shapes
• CPC Class Codes: A61F 2210/0004 bioabsorbable
• CPC Class Codes: A61F 2210/0076 multilayered, e.g. laminated structures
• CPC Class Codes: A61F 2230/0002 Two-dimensional shapes, e.g. cross-sections
• CPC Class Codes: A61F 2250/003 differing in adsorbability or resorbability, i.e. in adsorption or resorption time
• CPC Class Codes: A61F 2250/0054 differing in corrosion resistance
• CPC Class Codes: A61L 31/022 Metals or alloys
• CPC Class Codes: A61L 31/08 Materials for coatings
• CPC Class Codes: A61L 31/148 Materials at least partially resorbable by the body

Abstract

A bioerodible endoprosthesis erodes to a desirable geometry that can provide, e.g., improved mechanical properties or degradation characteristics.

Claims

1. An endoprosthesis, comprising:

a plurality of struts, the plurality of struts comprising a plurality of generally circumferential struts being interconnected to one another or connected by one or more connecting struts, wherein at least one strut of the plurality of struts comprises a bioerodible magnesium or a bioerodible magnesium alloy, the at least one strut having a longest dimension extending in a z-axis, the at least one strut having a cross-section in an X-Y plane perpendicular to the z-axis, wherein the at least one strut has an initial geometry in the X-Y plane characterized by initial dimensions, and

an erosion modifying material provided on the surface of the at least one strut which controls erosion to form a predetermined geometry such that, after erosion of at least about 50 percent of the area of the at least one strut in the X-Y plane, at least one initial dimension of the initial geometry is maintained in the X-Y plane.

2. The endoprosthesis of claim 1, wherein the initial dimension is maintained after erosion of at least about 75 percent of the area of the at least one strut in the X-Y plane.

3. The endoprosthesis of claim 1, wherein the initial dimension maintained corresponds to a maximum dimension of the initial geometry.

4. The endoprosthesis of claim 1, wherein the predetermined geometry is an X.

5. The endoprosthesis of claim 1, wherein the predetermined geometry is an interdigitated geometry.

6. The endoprosthesis of claim 1, wherein the predetermined geometry is a radially lobed structure.

7. The endoprosthesis of claim 1, wherein the predetermined geometry is a convex structure.

8. The endoprosthesis of claim 1, wherein the predetermined geometry is square or rectangular.

9. The endoprosthesis of claim 1, wherein the predetermined geometry extends substantially the full extent of the strut in the Z direction.

10. The endoprosthesis of claim 1, wherein the initial geometry is square or rectangular.

11. The endoprosthesis of claim 1, wherein the initial geometry is circular, ovaloid or elliptical.

12. The endoprosthesis of claim 1, wherein the ratio of maximum initial dimensions in the X-Y plane is between about 2:

1 and about 1;

2.

13. The endoprosthesis of claim 1, wherein the erosion modifying material comprises a material selected from the group consisting of a polymer, a ceramic, an oxide, a metal, an alloy, and a composite.

14. The endoprosthesis of claim 1 wherein the erosion modifying material is provided as a layer, and the layer has varying thickness.

15. The endoprosthesis of claim 14 wherein the thickness varies in the X or Y direction.

16. The endoprosthesis of claim 14 wherein the thickness varies in the Z direction.

17. The endoprosthesis of claim 14 wherein the thickness varies along the length of the endoprosthesis.

18. The endoprosthesis of claim 1 formed of a plurality of struts arranged in the general form of a tube.

19. The endoprosthesis of claim 1, wherein the endoprosthesis is balloon expandable.

23. The endoprosthesis of claim 1, wherein the bioerodible magnesium or the bioerodible magnesium alloy has an erosion rate of between about 0.2% and 5% of its initial mass per day.

20. An endoprosthesis, comprising:

a strut comprising a bioerodible magnesium or a bioerodible magnesium alloy, the strut having a longest dimension extending in a z-axis, the strut having a cross-section in an X-Y plane perpendicular to the z-axis, wherein the strut has an initial geometry in the X-Y plane characterized by initial dimensions, and

an erosion modifying material provided on the surface of the strut which controls erosion to form an I-shape in the X-Y plane after erosion of at least about 50 percent of the area of the strut in the X-Y plane.

21. The endoprosthesis of claim 20, wherein the ends of the I correspond to abluminal and adluminal sides of the endoprosthesis.

22. An endoprosthesis, comprising:

a plurality of struts, the plurality of struts comprising a plurality of generally circumferential struts being interconnected to one another or connected by one or more connecting struts, wherein at least one strut of the plurality of struts comprises a bioerodible magnesium or a bioerodible magnesium alloy, at least one strut having an initial geometry in X, Y, and Z directions, the at least one strut having a longest dimension extending in the Z direction, the X, Y, and Z directions each being perpendicular to each other; and

an erosion modifying material provided on the surface of the at least one strut which controls erosion to form a predetermined geometry such that, after erosion of at least about 50 percent of the at least one strut, at least two initial dimensions in the X, Y, and Z directions are maintained.