Sheaths Used in Polymer Scaffold Delivery Systems

• US 20120109281A1
• Filed: 10/29/2010
• Published: 05/03/2012
• Est. Priority Date: 10/29/2010
• Status: Active Grant

• Current Assignee: Abbott Cardiovascular Systems Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Abbott Cardiovascular Systems Incorporated (Abbott Laboratories Incorporated)
• Inventors: Papp, John E.
• Granted Patent: US 10,111,767 B2
• Time in Patent Office: Days
• US Class Current: 623/1.15
• CPC Class Codes: A61F 2/958 Inflatable balloons for placing stents or stent-grafts
• CPC Class Codes: A61F 2/97 the outer sleeve being splittable
• CPC Class Codes: A61F 2002/9583 Means for holding the stent on the balloon, e.g. using protrusions, adhesives or an outer sleeve
• CPC Class Codes: A61F 2002/9665 with additional retaining means
• CPC Class Codes: B29C 2793/0081 before shaping
• CPC Class Codes: B29C 48/09 Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
• CPC Class Codes: B29C 61/065 Preforms held in a stressed condition by means of a removable support; Supports therefor
• CPC Class Codes: B29C 63/42 using tubular layers or sheathings
• CPC Class Codes: B29C 65/56 using mechanical means or mechanical connections, e.g. form-fits
• CPC Class Codes: B29C 65/68 using auxiliary shrinkable elements
• CPC Class Codes: B29C 66/532 Joining single elements to the wall of tubular articles, hollow articles or bars
• CPC Class Codes: B29L 2028/00 Nets or the like
• CPC Class Codes: B29L 2031/7543 Balloon catheters
• CPC Class Codes: Y10T 29/49863 with prestressing of part

Abstract

A medical device includes a polymer scaffold crimped to a catheter having an expansion balloon. A sheath is placed over the crimped scaffold after crimping to reduce recoil of the crimped polymer scaffold. The sheath is removed before the medical device is implanted within the body.

Claims

1. A method for crimping, comprising:

providing a polymer scaffold having a first diameter (d1);

providing a balloon catheter;

crimping the scaffold to the balloon catheter including the step of reducing the scaffold diameter from the first diameter to a second diameter (d2) wherein the ratio of d1/d2 is at least about two; and

reducing recoil effects in the crimped scaffold including deforming a sheath to enable the sheath to be received over the crimped scaffold, and after being received over the crimped scaffold, allowing the sheath to return to an un-deformed state.

2. The method of claim 1, wherein the ratio d1/d2 is greater than about 3:

1 or between about 3;

1 to 4;

1.

3. The method of claim 1, wherein the sheath has an un-deformed inner diameter that is less than d2.

4. The method of claim 1, wherein the reducing recoil effects includes the step of stretching the sheath over a hollow tube, at least partially disposing the scaffold within the tube and then removing the sheath from the tube so as to allow the sheath to return to an un-deformed state while it attaches to the scaffold surface.

5. The method of claim 1, wherein the reducing recoil effects includes the step of supporting the deformed sheath between two ends, disposing the scaffold between the ends and within a bore of the sheath, then pulling the ends away from each other so that the sheath can return to its un-deformed and attach to the scaffold surface.

6. An apparatus including a medical device for being implanted within a body, comprising:

a polymer scaffold crimped to a delivery balloon; and

a sheath disposed over the crimped scaffold such that the sheath applies a radial preload to the scaffold to reduce recoil in the scaffold;

wherein the sheath is constructed in such a manner as to apply a radial preload to the scaffold to reduce recoil or maintain a dislodgment force in the scaffold when the sheath is attached to the scaffold.

7. The apparatus of claim 6, wherein the delivery balloon has a maximum inflated outer diameter d3, the scaffold has a crimped inner diameter d2 and the scaffold is cut from an expanded tube having an inner diameter d1, wherein d1/d2 is greater than 3:

1.

8. The apparatus of claim 7, wherein d3 is less than d1

9. The apparatus of claim 8, wherein d1/d2 is between 3:

1 and 4;

1.

10. The apparatus of claim 6, wherein the sheath has an inner diameter in its un-deformed state d4 that is less than d2.

11. The apparatus of claim 6, wherein the sheath includes indicia indicating the sequence of removal of the sheath from the scaffold by a health professional

12. The apparatus of claim 11, wherein the indicia include a plurality of colors.

13. The apparatus of claim 11, wherein the indicia include a plurality of pull tabs arranged to indicate the direction in which the tabs should be manually pulled to remove the sheath from the scaffold.

14. The apparatus of claim 6, wherein the sheath includes a substantially rectangular sheet wrapped around the scaffold and removable by one or more pull tabs.

15. The apparatus of claim 6, wherein the sheath includes a substantially rectangular sheet being pre-disposed to roll up on itself.

16. The apparatus of claim 6, wherein the sheath includes a helical wrap extending over about the length of the scaffold.

17. The apparatus of claim 6, wherein the sheath includes a sheath having a plurality of slits defining flaps, wherein the flaps are disposed near the proximal or distal end of the scaffold, wherein the flaps are configured for being manually griped and pulled apart to initiate a tearing of the sheath without dislodgment of the scaffold form the balloon.

18. The apparatus of claim 17, wherein the sheath is a multi-layer sheath having a lubricous inner liner and an elastic outer layer.

19. The apparatus of claim 6, wherein the sheath includes a tab disposed near a removable fastener.

20. The apparatus of claim 6, wherein the sheath includes a pull tab disposed near a removable fastener and configured for being pulled in a direct traverse to a longitudinal axis of the scaffold.

21. A method for providing a medical device suitable for implantation within a body, comprising:

crimping a polymer scaffold to a balloon catheter; and

disposing a sheath over the crimped scaffold to reduce recoil in the crimped scaffold, wherein the disposing step corresponds to only one of the following;

warming a sheath to above a medical device storage temperature, radially expanding the warmed sheath, and then disposing the warmed and radially expanded sheath over the crimped scaffold to apply a radial pre-load to the scaffold, the sheath including a removal portion, and

providing a sheath having a plurality of tabs to enable manual attachment and removal of the sheath from the scaffold using the plurality of tabs;

wherein upon manual removal of the sheath using the removal portion or tabs, respectively, the crimped scaffold and balloon catheter become suitable for implantation within a body.