Patent ID: 7871550
Filing Date: 2011-01-18
Classification: A61F,A61L,B29C,B29K

Abstract:
1. A method of making an ePTFE tubular structure comprising the following steps: forming a tube of polytetrafluoroethylene having a luminal surface and an abluminal surface; longitudinally stretching said polytetrafluoroethylene tube to form an expanded polytetrafluoroethylene tube, wherein said expanded polytetrafluoroethylene tube is comprised of fibrils having a first length and oriented in a longitudinal direction of said expanded polytetrafluoroethylene tube and nodes having a first length and oriented in a circumferential direction of said expanded polytetrafluoroethylene tube; placing said expanded polytetrafluoroethylene tube circumferentially around a longitudinal foreshortening and radially expanding mechanism; applying radial pressure from said longitudinal foreshortening and radially expanding mechanism; and radially expanding and longitudinally foreshortening said expanded polytetrafluoroethylene tube over said longitudinal foreshortening and radially expanding mechanism by using said mechanism to apply an outwardly directed force to said luminal surface of said polytetrafluoroethylene tube to increase said first length of said nodes of said expanded polytetrafluoroethylene to a second length in the circumferential direction, to shift said fibrils of said expanded polytetrafluoroethylene tube non-longitudinally by hingeably rotating said fibrils of said expanded polytetrafluoroethylene tube and to form an ePTFE tubular structure with reoriented fibrils; said reoriented fibrils of said ePTFE tubular structure have a second length substantially equal to said first length of said fibrils of said expanded polytetrafluoroethylene tube; said ePTFE tubular structure being configurable between a first configuration and a second configuration without elastic recovery, said first configuration having a first tubular diameter and a first tubular length and a second configuration having a second tubular diameter and a second tubular length, said first tubular length being greater than said second tubular length and said second tubular diameter being greater than said first tubular diameter; and wherein said expanded polytetrafluoroethylene tube is heated to a temperature of between about 200° F. and 350° F. during the radially expanding and longitudinally foreshortening step.