Methods of treatment with stents with enhanced fracture toughness

• US 9,522,503 B2
• Filed: 11/21/2013
• Issued: 12/20/2016
• Est. Priority Date: 06/15/2006
• Status: Active Grant

• Current Assignee: Abbott Cardiovascular Systems Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Abbott Cardiovascular Systems Incorporated (Abbott Laboratories Incorporated)
• Inventors: Gale, David C., Huang, Bin, Limon, Timothy A., Gueriguian, Vincent A.
• Primary Examiner(s): Sweet, Thomas J
• Assistant Examiner(s): WOLF, MEGAN YARNALL
• Application Number:
  US14/086,921
• Publication Number:
  US 20140094899A1
• Time in Patent Office: 1,125 Days
• US Class Current: 1/1
• CPC Class Codes: A61F 2/90 characterised by a net-like or mesh-like structure
• 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 2/9522 Means for mounting a stent or stent-graft onto or into a placement instrument
• CPC Class Codes: A61F 2002/91533 characterised by the phase between adjacent bands
• CPC Class Codes: A61F 2002/91558 connected peak to peak
• CPC Class Codes: A61F 2002/91566 connected trough to trough
• CPC Class Codes: A61F 2002/91583 by a bridge, whereby at least one of its ends is connected along the length of a strut between two consecutive apices within a band
• CPC Class Codes: A61F 2210/0004 bioabsorbable
• CPC Class Codes: A61F 2220/0016 with sharp anchoring protrusions, e.g. barbs, pins, spikes
• CPC Class Codes: A61L 31/06 obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds A61L31/041 takes precedence
• CPC Class Codes: A61L 31/14 Materials characterised by their function or physical properties , e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
• CPC Class Codes: A61L 31/148 Materials at least partially resorbable by the body
• CPC Class Codes: B29C 2049/7831 characterised by pressure values or ranges
• CPC Class Codes: B29C 2793/0009 Cutting out
• CPC Class Codes: B29C 2949/08 Preforms made of several individual parts, e.g. by welding or gluing parts together
• CPC Class Codes: B29C 35/045 using gas or flames
• CPC Class Codes: B29C 49/0005 characterised by the material
• CPC Class Codes: B29C 49/14 Clamps
• CPC Class Codes: B29C 49/4273 Auxiliary operations after the blow-moulding operation not otherwise provided for
• CPC Class Codes: B29C 49/4823 : with incorporated heating or cooling means
• CPC Class Codes: B29C 55/22 : of tubes B29C61/08 takes precedence
• CPC Class Codes: B29C 55/24 : radial
• CPC Class Codes: B29C 69/001 : a shaping technique combined with cutting, e.g. in parts or slices combined with rearranging and joining the cut parts for reinforced material B29C70/545; B29C49/4278, B29C51/268 take precedence
• CPC Class Codes: B29K 2067/00 : Use of polyesters or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2067/046 : PLA, i.e. polylactic acid or polylactide
• CPC Class Codes: B29K 2105/258 : Tubular
• CPC Class Codes: B29K 2995/006 : Bio-degradable, e.g. bioabsorbable, bioresorbable or bioerodible
• CPC Class Codes: B29L 2031/7534 : Cardiovascular protheses
• CPC Class Codes: C08L 67/04 : Polyesters derived from hydroxycarboxylic acids, e.g. lactones C08L67/06 takes precedence
• CPC Class Codes: Y10T 156/1026 : with slitting or removal of material at reshaping area prior to reshaping

Abstract

Stents and methods of manufacturing a stents with enhanced fracture toughness are disclosed.

Claims

1. A method of treating a blood vessel with a biodegradable stent comprising:

deploying a biodegradable stent in a blood vessel from a crimped diameter to an intended deployment diameter, the biodegradable stent including a cylindrically-shaped scaffold comprising a poly(L-lactide)-based biodegradable polymer,

wherein the scaffold includes a pattern comprising a plurality of cylindrical rings of struts and longitudinal linking struts connecting the rings, the scaffold formed by cutting the pattern in a tube,

wherein the tube has been processed to increase crystallinity prior to cutting the pattern, the biodegradable polymer after the processing has a crystallinity of less than 50%,

wherein the rings include bending elements, each bending element including struts that bend outward when the scaffold is deployed to allow for radial expansion of the scaffold,

wherein curved portions of the bending elements have no cracks at the crimped diameter,

wherein cracks form in the curved portions of the bending elements when the stent is deployed to the intended deployment diameter,

wherein the bending elements have an angle greater than 90°

at a diameter the pattern is cut, and

wherein the scaffold has adequate radial strength to hold open the blood vessel.

2. The method of claim 1, wherein the processing comprises radially expanding the tube to an expanded diameter prior to forming the pattern in the tube at the expanded diameter, the radial expansion providing induced molecular orientation in the circumferential direction in the scaffold.

3. The method of claim 1, wherein the scaffold has induced molecular orientation in the circumferential direction.

4. The method of claim 1, wherein the processing comprises heating the tube to a temperature above a glass transition temperature (Tg) of the biodegradable polymer.

5. The method of claim 1, wherein the bending elements have an angle greater than 110°

at the diameter the pattern is cut.

6. The method of claim 1, wherein the biodegradable polymer after the processing has a crystallinity less than 40%.

7. The method of claim 1, wherein the biodegradable polymer after the processing has a crystallinity less than 20%.

8. The method of claim 1, wherein the stent is stored at ambient temperature until the treatment.

9. The method of claim 1, wherein the crimped diameter is 0.055 in.

10. The method of claim 1, wherein the intended deployment diameter is 0.158 in.

11. A method of treating a blood vessel with a biodegradable stent comprising:

deploying a biodegradable stent in a blood vessel from a crimped diameter to an intended deployment diameter, the biodegradable stent including a cylindrically-shaped scaffold including a pattern of interconnected struts formed by cutting the pattern in a tube, wherein the scaffold comprises a poly(L-lactide)-based biodegradable polymer, the scaffold having a first end and a second end,

wherein the tube has been processed to increase crystallinity prior to cutting, the biodegradable polymer after the processing has a crystallinity of less than 50%,

wherein the pattern comprises a plurality of cylindrical rings of struts and longitudinal linking struts connecting the rings,

wherein the rings include bending elements, each bending element including struts that bend outward when the scaffold is deployed to allow for radial expansion of the scaffold, each bending element comprising an apex,

wherein cracks form in curved portions of the bending elements when the stent is deployed to the intended deployment diameter,

wherein the bending elements comprise free bending elements, W-shaped bending elements, and Y-shaped bending elements,

wherein the free bending elements are not directly connected to any adjacent ring, each W-shaped bending element is directly connected by one of the linking struts at a concave portion of the apex of the W-shaped bending element to a convex portion of an apex on an adjacent ring located in a direction of the first end, and each Y-shaped bending element is directly connected by one of the linking struts at a convex portion of the apex of the Y-shaped bending element to a concave portion of an apex on an adjacent ring located in a direction of the second end,

wherein each of the apices of one of the rings is opposed to an apex on two adjacent rings, and the opposing apices are directed toward the same end of the scaffold,

wherein the bending elements have an angle greater than 90°

at a scaffold diameter that the pattern is cut, and

wherein the scaffold has adequate radial strength to hold open the blood vessel.

12. The method of claim 11, wherein the processing comprises radially expanding the tube to an expanded diameter prior to cutting the pattern in the tube at the expanded diameter, the radial expansion providing induced molecular orientation in the circumferential direction in the scaffold.

13. The method of claim 11, wherein the scaffold has induced molecular orientation in the circumferential direction.

14. The method of claim 11, wherein the processing comprises heating the tube to a temperature above a glass transition temperature (Tg) of the biodegradable polymer.

15. The method of claim 11, wherein the bending elements have an angle greater than 110°

.

16. The method of claim 11, wherein the biodegradable polymer after the processing has a crystallinity less than 40%.

17. The method of claim 11, wherein the biodegradable polymer after the processing has a crystallinity less than 20%.

18. The method of claim 11, wherein the stent is stored at ambient temperature until the treatment.

19. The method of claim 11, wherein a repeating sequence of bending elements in each of the rings is free bending element, followed by Y-shaped bending element, followed by free bending element, and followed by W-shaped bending element.

20. The method of claim 11, wherein the curved portions of the bending elements have no cracks at the crimped diameter.