Expandable stent with wrinkle-free elastomeric cover
View Patent ↗An improved stent-graft device is provided that delivers a smooth flow surface over a range of operative expanded diameters by applying a unique cover material to the stent through a technique that allows the cover to become wrinkle-free prior to reaching fully deployed diameter. The unique cover material then allows the device to continue to expand to a fully deployed diameter while maintaining a smooth and coherent flow surface throughout this additional expansion. Employed with a self-expanding device, when the device is unconstrained from a compacted diameter it will self-expand up to a fully deployed diameter with the graft being substantially wrinkle-free over diameters ranging from about 30-50% to 100% of the fully deployed diameter. Preferably, the graft component comprises an elastomeric material, such as silicone, polyurethane, or a copolymer of PAVE-TFE.
1. A method for producing a self expanding stent-graft device that comprises
providing a stent having a fully compacted diameter, a fully expanded diameter, and an intermediate diameter between the fully compacted diameter and the fully expanded diameter;
orienting the stent at its fully expanded diameter;
forming an elastomeric cover on the stent to form the stent-graft;
orienting the stent at its intermediate diameter at a temperature less than the temperature that would induce the stent to self-expand; and
re-flowing the elastomeric cover at a temperature less than the temperature that would induce the stent to self-expand to be substantially wrinkle-free at such intermediate diameter,
wherein the stent-graft is substantially wrinkle-free when self expanding from the intermediate diameter to the fully expanded diameter of the stent.
2. The method of claim 1 that further comprises compacting the resulting stent-graft and placing into a delivery system before said stent warms to a temperature that would induce the stent to self-expand.
3. The method of claim 1 , wherein said elastomeric cover is dipcoated onto the stent.
4. The method of claim 1 , wherein said elastromeric cover comprises at least one of the materials selected from the group consisting of polyurethanes, silicone materials, perfluoroethylvinylether (PEVE), tetrafluoroethylene (TFE), perfluoropropylvinylether (PPVE), perfluoromethylvinylether (PMVE), perfluoroethylvinylether-tetrafluoroethylene (PEVE-TFE), perfluoropropylvinylether-tetrafluoroethylene (PPVE-TFE), and perfluoromethylvinylether-tetrafluoroethylene (PMVE-TFE).
5. The method of claim 4 , wherein said material is perfluoromethylvinylether-tetrafluoroethylene (PMVE-TFE).