Medical implants with limited resistance to migration

• US 20070093888A1
• Filed: 10/25/2005
• Published: 04/26/2007
• Est. Priority Date: 10/25/2005
• Status: Active Grant

• Current Assignee: Boston Scientific Scimed, Inc. (Boston Scientific Corporation)
• Original Assignee: Scimed Life Systems Incorporated (Boston Scientific Corporation)
• Inventors: Wolfson, Mark, Thistle, Robert
• Granted Patent: US 8,292,946 B2
• Time in Patent Office: Days
• US Class Current: 623/1.36
• CPC Class Codes: A61F 2/90 characterised by a net-like or mesh-like structure
• CPC Class Codes: A61F 2002/825 having longitudinal struts
• CPC Class Codes: A61F 2002/8486 provided on at least one of the ends
• CPC Class Codes: A61F 2220/0016 with sharp anchoring protrusions, e.g. barbs, pins, spikes
• CPC Class Codes: A61F 2230/0017 Angular shapes

Abstract

An implant adapted to be retained in a body lumen includes a barb for engaging the lumen wall. The barb includes a yieldable element adapted to yield in response to a force, above a predetermined limit, tending to cause migration of the implant. The barb may comprise a shape memory material adapted to change shape when the material undergoes a stress induced phase change and thereby to disengage from the lumen wall.

Claims

1. A barb for retaining an implant in a body lumen, the barb comprising at least a first element adapted to be attached to or comprise a part of the implant and a second element adapted to engage a lumen in which the implant is adapted to be deployed, said second element comprising a yieldable material, said second element being adapted to resist any force tending to displace the implant to which the first element is attached when that force is below a pre-determined force limit and also being adapted to yield to any force tending to displace the implant when that force exceeds the pre-determined force limit.

2. The barb, as recited in claim 1, comprised of a shape memory material which yields by undergoing a stress induced phase change and thereby disengages the barb and the implant from the lumen when the pre-determined force limit is exceeded.

3. The barb of claim 1, wherein the implant is a stent.

4. An implant adapted to be retained in a body lumen including a barb as recited in claim 1 for engaging a lumen wall.

5. The barb as recited in claim 2, wherein at least one part of the barb is comprised of Nitinol.

6. The barb-stent combination as recited in claim 3 wherein the first barb element is an integral part of the stent.

7. The barb-stent combination as recited in claim 3 wherein the first barb element is secured to the stent.

8. The barb-stent combination as recited in claim 7 wherein the first barb element is secured to the stent by a crimp tube in which an element of the stent is also secured.

9. The barb-stent combination as recited in claim 3 wherein the first barb element is secured to the stent by a crimp tube in which a plurality of stent elements are also secured, said plurality of stent elements comprising the wire ends of a mesh stent segment and a second stent element adjacent the mesh stent segment.

10. The barb-stent combination as recited in claim 9 wherein the stent elements secured in said crimp tube are adjacent wire ends of the mesh stent segment and the second stent element which includes an open cell structure adapted to be deployed in an aorta adjacent a juncture with renal arteries.

11. A method of affixing an implant in a body lumen such that axial force on the implant is resisted below a pre-selected implant force limit and not resisted above that limit, the method comprising:

(a) providing the implant with at least one shape memory material element adapted to affix the implant to the body lumen up to the preselected implant force limit and to resist axial force on the implant, the shape memory material element being adapted to undergo a stress induced phase change from an elastic state to a yieldable state at the pre-selected implant force limit, a pre-selected force limit of all of said at least one shape memory material element corresponding to the pre-selected implant force limit of the implant pre-selected stress limit; and

(b) locating said implant in the body lumen; and

(c) affixing said implant to the body lumen thereto by engagement of the shape memory element.

12. An implant adapted to be affixed in a body lumen such that axial force on the implant is resisted below a pre-selected implant force limit and not resisted above that force limit, the implant comprising:

a plurality of shape memory material elements adapted to affix the implant to the body lumen up to the pre-selected implant force limit and to resist axial force on the implant, each of the shape memory material elements being adapted to undergo a stress induced phase change from an elastic state to a yieldable state at a pre-selected element force limit, the sum of the pre-selected element force limits of all of said elements corresponding to the pre-selected implant force limit.