Crush Recoverable Polymer Scaffolds

• US 20110190871A1
• Filed: 01/27/2011
• Published: 08/04/2011
• Est. Priority Date: 01/30/2010
• Status: Active Grant

• Current Assignee: Abbott Cardiovascular Systems Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Abbott Cardiovascular Systems Incorporated (Abbott Laboratories Incorporated)
• Inventors: Solter, Zella, Jayasinghe, Dudley, Hossainy, Syed, Nikanorov, Alexander, Anukhin, Boris, Trollsas, Mikael, Papp, John, Ngo, Michael H.
• Granted Patent: US 8,568,471 B2
• Time in Patent Office: Days
• US Class Current: 623/1.15
• CPC Class Codes: A61F 2/82 Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents stent-grafts for tubular structures of the body other than blood vessels A61F2/04; stent-grafts for blood vessels A61F2/07; instruments specially adapted for placement or removal of stents or stent-grafts A61F2/95; for closing wounds, or holding wounds closed A61B17/04 - A61B17/115; dilators A61M29/00
• CPC Class Codes: A61F 2/844 folded prior to deployment
• CPC Class Codes: A61F 2/86 Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure
• 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 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 2/958 Inflatable balloons for placing stents or stent-grafts
• CPC Class Codes: A61F 2002/825 having longitudinal struts
• CPC Class Codes: A61F 2002/91558 connected peak to peak
• CPC Class Codes: A61F 2002/91566 connected trough to trough
• CPC Class Codes: A61F 2002/91575 connected peak to trough
• CPC Class Codes: A61F 2210/0004 bioabsorbable
• CPC Class Codes: A61F 2210/0014 using shape memory or superelastic materials, e.g. nitinol
• CPC Class Codes: A61F 2210/0019 operated at only one temperature whilst inside or touching the human body, e.g. constrained in a non-operative shape during surgery, another temperature only occurring before the operation
• CPC Class Codes: A61F 2210/0076 multilayered, e.g. laminated structures
• CPC Class Codes: A61F 2230/0006 circular
• CPC Class Codes: A61F 2230/0008 elliptical or oval
• CPC Class Codes: A61F 2250/0067 Means for introducing or releasing pharmaceutical products into the body
• CPC Class Codes: A61F 2250/0096 Markers and sensors for detecting a position or changes of a position of an implant, e.g. RF sensors, ultrasound markers
• CPC Class Codes: A61F 2250/0098 : radio-opaque, e.g. radio-opaque markers
• CPC Class Codes: A61L 27/00 : Materials for grafts or prostheses or for coating grafts or prostheses dental prostheses A61C13/00; shape or structure of prostheses A61F2/00; use of preparations for artificial teeth A61K6/80; artificial kidneys A61M1/14
• 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: B21D 39/046 : Connecting tubes to tube-like fittings
• CPC Class Codes: B29C 2035/0838 : using laser
• CPC Class Codes: B29C 35/08 : by wave energy or particle radiation B29C64/00, B29C71/04 take precedence
• CPC Class Codes: B29K 2067/046 : PLA, i.e. polylactic acid or polylactide
• CPC Class Codes: B29L 2023/00 : Tubular articles B29L2024/00 takes precedence ; catheters B29L2031/7542
• CPC Class Codes: B29L 2031/7543 : Balloon catheters
• CPC Class Codes: C08L 67/04 : Polyesters derived from hydroxycarboxylic acids, e.g. lactones C08L67/06 takes precedence
• CPC Class Codes: C08L 71/02 : Polyalkylene oxides
• CPC Class Codes: Y10T 29/49826 : Assembling or joining
• CPC Class Codes: Y10T 29/4987 : Elastic joining of parts
• CPC Class Codes: Y10T 29/49908 : Joining by deforming
• CPC Class Codes: Y10T 29/49925 : Inward deformation of aperture or hollow body wall
• CPC Class Codes: Y10T 29/49927 : Hollow body is axially joined cup or tube

Abstract

A medical device includes a polymer scaffold crimped to a catheter having an expansion balloon. The scaffold, after being deployed by the balloon, provides a crush recovery of about 90% after the diameter of the scaffold has been pinched or crushed by 50%. The scaffold has a pattern including an asymmetric closed cell connecting links connecting the closed cells.

Claims

1. A balloon-expandable medical device for being implanted in a peripheral vessel of the body, comprising:

a scaffold formed from a polymer tube

configured for being crimped to a balloon,

the scaffold having a pattern of interconnected elements and

the scaffold having an expanded diameter when expanded from a crimped state by the balloon,

wherein the scaffold attains greater than about 90% of its diameter after being crushed to at least 33% of its expanded diameter; and

wherein the scaffold has a radial stiffness greater than 0.3 N/mm.

2. The medical device of claim 1, the interconnected elements comprising a strut and a link, wherein an aspect ratio (AR) of the width to wall thickness of the strut or link is between 0.4 and 1.4.

3. The medical device of claim 2, wherein the AR is between 0.4 to 0.9, the scaffold wall thickness is between 0.008 inches and 0.014 inches and the scaffold expanded diameter is between 5 mm and 8 mm.

4. The medical device of claim 2, wherein the AR is between 0.8 to 1.4 the scaffold wall thickness is between 0.008 inches and 0.014 inches and the scaffold expanded diameter is between 5 mm and 8 mm.

5. The medical device of claim 2, wherein the struts form rings having crowns and the rings are interconnected by longitudinally extending links, wherein the crowns have a maximum crown angle between about 90 degrees and 115 degrees when the scaffold has the expanded diameter.

6. The medical device of claim 1, wherein the scaffold has rings formed by struts, and there are no more than 9 crowns in a ring and 3 links connecting the ring to an adjacent ring;

and

wherein in an as-fabricated state;

the scaffolding has an outer diameter of 8 to 10 mm, the crown angles for rings of the scaffold are between 90 and 115 degrees, and the scaffold has a wall thickness of at least 0.008 in.

7. The medical device of claim 6,

wherein the network of interconnected struts and links form a plurality of closed cells, each closed cell having a first end circumferentially spaced from an opposing second end and a pair of bending elements extending between the circumferentially spaced ends, each bending element forming at least two crowns,

wherein the first and second ends of a closed cell are shared with an adjacent cell, and

wherein adjacent cylindrical rings are connected to each other by longitudinal links such that the longitudinal links connecting a ring to its two, adjacent rings are not co-linear with each other.

8. The medical device of claim 2, the scaffolding including an asymmetric closed cell formed by struts, wherein the closed cell is asymmetric both with respect to a longitudinal bending axis and the longitudinal axis of the scaffold, which is perpendicular to the bending axis.

9. The medical device of claim 2, the scaffolding including an asymmetric closed cell having bending elements comprising struts forming crowns, crowns connected to links, Y-crowns and W-crowns, wherein more than one unconnected crown is disposed between a Y-crown and a W-crown.

10. The medical device of claim 1, wherein the scaffold has a ratio of pinching stiffness to wall thickness×

tube diameter of about 0.08 to 0.18 N/mm³.

11. The medical device of claim 10, wherein the scaffold has a ratio of pre-crimp diameter to wall thickness of between about 30 and 60,

the scaffold is fabricated to have a pair of adjacent rings, wherein the ring pair forms no more than three closed cells, and

the scaffold is fabricated from a PLLA tube.

12. The medical device of claim 11, wherein the scaffold has a wall thickness between about 0.008 inches and 0.014 inches.

16. The medical device of claim 1, the scaffold further including a radiopaque marker disposed on a link connecting rings,

wherein the marker is held in a depot formed on the link,

wherein the space between a ring and link in the scaffold'"'"'s crimped state is substantially less than the length or width of the depot, and

wherein the depot is disposed between adjacent rings in the crimped state such that the scaffold is capable of attaining the same crimped profile with or without the marker.

21. The medical device of claim 1, wherein the polymer is PLLA, or a blend of PLLA with a polymer having a lower T_g than PLLA, or a block co-polymer, or a multi-layered structure having different T_g values for the material of different layers.

22. The medical device of claim 1, wherein the block co-polymer or blend is PLLA with PEG (poly-ethylene glycol).

13. A balloon-expandable medical device, comprising:

a crimped scaffold that when deployed by a balloon forms a scaffold having an expanded diameter;

wherein the scaffold is capable of regaining more than 90% of its diameter after being crushed to at least 75% of its expanded diameter; and

wherein the scaffold comprises

a radial stiffness greater than about 0.3 N/mm, and

a radial strength, pinching strength, pinching stiffness and fracture toughness of a pre-crimp scaffold having a pre-crimp diameter between 300-400% greater than a diameter of the crimped scaffold.

14. The medical device of claim 13, wherein the pre-crimp diameter is greater than the expanded diameter and wherein the acute recoil of the scaffold from the expanded diameter is less than about 5%.

15. The medical device of claim 14, wherein the pre-crimp scaffold is made from a radially expanded PLLA tube.

17. The medical device of claim 13, further including a radiopaque foil disposed over a link connecting an end ring of the scaffold to an interior ring.

18. The medical device of claim 13, further including a radiopaque marker disposed at or near a crown of an end ring of the scaffold.

19. A radially expandable stent comprising:

a balloon expandable scaffold formed from a PLLA tube,

the scaffold including a plurality of radially expandable undulating rings formed by struts, wherein the undulating rings of struts comprise crowns, wherein adjacent rings are connected by longitudinal links, wherein a ring has no more than 9 crowns and 3 links around its circumference, and the angle at any crown is less than 115 degrees;

the scaffold has an outer diameter of 8 to 10 mm; and

the scaffold has a wall thickness at least about 0.008″

.

20. A peripherally implantable medical device, comprising:

a crimped scaffold that when expanded by a balloon forms a scaffold having a diameter;

the scaffold regains more than 90% of the diameter after being crushed to at least 67% of the diameter,

the scaffold is formed from PLLA,

the scaffold has a diameter to wall thickness ratio of between about 30 and 60;

the scaffold has struts and links, wherein a strut and/or link has a width to thickness ratio of between about 0.8 and 1.4, and

the scaffold has a radial stiffness greater than or equal to about 0.3 N/mm.