Elastic stent graft
A stent graft including (1) a stent having a wall having at least one opening, an outer surface, and an inner surface and (2) a covering of a composite material having a least one expanded fluoropolymer membrane and an elastomer is provided. The cover can be used to cover the outer and/or the inner surface of the stent. The expanded fluoropolymer membrane contains serpentine fibrils. In exemplary embodiments, the fluoropolymer is polytetrafluoroethylene. The composite material may be axially and/or circumferentially wrapped around the stent. The composite material is fold-free throughout its operating diameter range and exhibits a sharp increase in stiffness at a predetermined diameter. The stent graft can be designed to have a stop point in either a radial or axial direction. The stent graft can advantageously be implanted undersized with respect to a nominal diameter without having material infolding.
1 . A method of assembling an implantable medical device onto a delivery system, the method comprising:
reducing the implantable medical device from a first diameter to a second diameter for assembly onto a delivery system, the implantable medical device including an implantable tubular member supported by a tubular support member, the first diameter being a diameter of the implantable medical device upon application of the implantable tubular member to the tubular support member, the implantable tubular member being substantially wrinkle-free at the second diameter.
2 . The method of claim 1 , wherein the implantable tubular member that is substantially wrinkle-free at the second diameter includes a composite material including an expanded fluoropolymer membrane and an elastomer.
3 . The method of claim 2 , wherein the expanded fluoropolymer membrane includes expanded polytetrafluoroethylene.
4 . The method of claim 2 , wherein the expanded fluoropolymer membrane includes serpentine fibrils, wherein each serpentine fibril curves or turns generally one way and then generally in another way.
5 . The method of claim 4 , wherein the expanded fluoropolymer membrane comprises a microstructure including fibrils, the fibrils being substantially only serpentine fibrils.
6 . The method of claim 4 , wherein the serpentine fibrils have a width greater than 0 micron and less than 1.0 micron.
7 . The method of claim 4 , wherein the serpentine fibrils have a width greater than 0 micron and less than 0.5 micron.
8 . The method of claim 1 , wherein the second diameter is 80% of the first diameter.
9 . The method of claim 1 , wherein the implantable medical device is substantially wrinkle-free before reducing to the second diameter.
10 . A method of deploying an implantable tubular member, the method comprising:
applying an expansion force to expand the implantable tubular member from a first diameter to a second diameter, the implantable tubular member including a microstructure of serpentine fibrils, the serpentine fibrils substantially straightening while the implantable tubular member is expanding until reaching a stop point, the stop point being configured to create a sharp increase in stiffness such that the implantable tubular member does not further expand after reaching the stop point, the implantable tubular member configured to return to the first diameter from the second diameter following removal of the expansion force.
11 . The method of claim 10 , wherein the stop point is in either a radial or axial direction.
12 . The method of claim 10 , wherein the implantable tubular member is substantially wrinkle-free at the second diameter.
13 . The method of claim 10 , wherein during expansion of the implantable tubular member, the stop point is reached at a predetermined diameter.
14 . The method of claim 10 , wherein the second diameter is 80% or greater than the first diameter.
15 . The method of claim 10 , wherein the stop point is at a diameter greater than the first diameter.
16 . A method of delivering an implantable tubular member into a body conduit of a patient, the method comprising:
deploying the implantable tubular member into the body conduit when the implantable tubular member is in a first configuration, the implantable tubular member including a composite material including an expanded fluoropolymer membrane and an elastomer, the expanded fluoropolymer membrane including a microstructure including fibrils, the fibrils being serpentine fibrils;
moving the implantable tubular member to a repair site within the body conduit;
expanding the implantable tubular member from the first configuration to a second configuration; and
applying an expansion force to further expanding the implantable tubular member from the second configuration to a third configuration, the implantable tubular member being substantially wrinkle-free at the third configuration, the implantable tubular member configured to return to the second configuration from the third configuration following removal of the expansion force.
17 . The method of claim 16 , wherein each serpentine fibril curves or turns generally one way and then generally in another way.
18 . The method of claim 16 , wherein the serpentine fibrils have a width greater than 0 micron and less than 1.0 micron.
19 . The method of claim 16 , wherein the serpentine fibrils have a width greater than 0 micron and less than 0.5 micron.
20 . The method of claim 16 , wherein implantable tubular member has a third diameter in the third configuration, the third diameter being 80% or greater than a second diameter in the second configuration of the implantable tubular member.