Methods of manufacturing a cover for an inflatable balloon
The present disclosure describes implantable medical devices comprising covers, such as a balloon cover. Such devices can comprise a first layer of a porous polymeric material, such as ePTFE, surrounded by layers of a porous polymeric material having an imbibed elastomer, such as polyurethane. The cover can be used to assist in deployment of an expandable implant, such as a stent-graft, within the body of the patient.
1. A method of manufacturing a cover comprising: imbibing a portion of a first surface of a single continuous porous polymeric sheet with an elastomeric component to form an imbibed zone, wherein a remaining portion of the first surface of the single continuous porous polymeric sheet that is not imbibed forms a non-imbibed zone, the imbibed zone and the non-imbibed zone forming a partially imbibed sheet; wrapping the partially imbibed sheet on a mandrel to form a first polymeric layer defined by a portion of the single continuous porous polymeric sheet; and wrapping the partially imbibed sheet on the mandrel to form at least one composite layer defined by another portion of the single continuous porous polymeric sheet and comprising the porous polymeric sheet imbibed with the elastomeric component to form the cover.
2. The method of claim 1 , wherein the partially imbibed sheet comprises ePTFE.
3. The method of claim 1 , wherein the partially imbibed sheet is wrapped such that the non-imbibed zone contacts a second surface of the partially imbibed sheet and the imbibed zone contacts the second surface of the partially imbibed sheet.
4. The method of claim 1 , wherein the partially imbibed sheet possesses a first direction of matrix tensile strength that is higher than that of a second direction, and wherein a direction of wrapping is substantially perpendicular to the first direction of the partially imbibed sheet.
5. The method of claim 1 , wherein the partially imbibed sheet possesses a first direction of matrix tensile strength that is higher than a second direction, and wherein the first direction of matrix tensile strength of the partially imbibed sheet is helically oriented about the mandrel.
6. The method of claim 1 , wherein the partially imbibed sheet possesses a first direction of matrix tensile strength that is higher than a second direction, and wherein the first direction of matrix tensile strength of the partially imbibed sheet is circumferentially oriented about the mandrel.
7. The method of claim 1 , wherein the partially imbibed sheet comprises an isotropic porous polymer.
8. The method of claim 1 , wherein a depth of the imbibed zone is at least equal to a perimeter of the mandrel.
9. The method of claim 1 , wherein a depth of the imbibed zone is at least twice a perimeter of the mandrel.
10. The method of claim 1 , wherein a depth of the non-imbibed zone is greater than a perimeter of the mandrel.
11. The method of claim 1 , wherein the partially imbibed sheet is wrapped around the mandrel at least ten (10) times.
12. The method of claim 1 , further comprising the steps of:
coaxially surrounding a balloon with the cover; and
thermally bonding at least a portion of the cover to the balloon.
13. The method of claim 12 , wherein the balloon comprises at least one pleat prior to coaxially surrounding the balloon with the cover.
14. The method of claim 1 , further comprising the steps of: thermally treating the first polymeric layer and the at least one composite layer comprising the single continuous porous polymer sheet imbibed with the elastomeric component to form the cover;
allowing the cover to cool;
removing the cover from the mandrel;
coaxially surrounding a balloon with the cover;
inflating the balloon and the cover to a working pressure; and
pleating the balloon and the cover while deflating the balloon and the cover.
15. The method of claim 14 , wherein the working pressure is about 6 psi.
16. The method of claim 14 , wherein the balloon in the step of coaxially surrounding the balloon with the cover is a pleated balloon.
17. The method of claim 14 , wherein the step of coaxially surrounding the balloon with the cover further comprises coaxially surrounding a non-pleated balloon with the cover.
18. The method of claim 14 , further comprising the steps of rolling at least one pleat of the balloon and the cover in a radial direction.