Abstract: A more porous PTFE is obtained by impressing a pattern into extruded PTFE and then expanding the PTFE. The pattern can be impressed by knurling or, preferably, by rolling the sheet between rollers having a pseudo-random pattern formed on the surface of the roller. The uniformity of the pores is controlled by the pattern; viz. a coarse pattern produces a wider distribution of internodal distances than a finer pattern.

Abstract: A dual porosity PTFE tube including an inner surface of expanded PTFE material having a first porosity and an outer surface of expanded PTFE material having a porosity different from that of the inner surface. The preferred method includes the step of forming inner and outer preformed tubular billets of PTFE resin particles mixed with a lubricant; the outer billet is adapted to closely fit around and concentric to the inner billet. Porosity of the inner and outer surfaces is varied by changing, in the respective billets, the lubrication level and/or the PTFE resin characteristic average particle size. The inner billet is placed inside the outer billet, and the two are extruded together, thereby melding the two billets. The extrudate is then longitudinally expanded and sintered. The inner surface of the resulting PTFE tube exhibits a different porosity than the outer surface of the tube; the porosities of the inner and outer surfaces are both within a range of about 0.10-200.mu..

Abstract: A uniformly expanded PTFE film is provided by extruding a PTFE film and gripping the unexpanded film about its periphery with a number of symmetrically disposed gripping members each equidistant from the center of the film. The extruded PTFE film is heated to a temperature in the range of 200-300 degrees Centigrade before expanding the extruded PTFE film. The gripping members are simultaneously rotated through an arc away from the center of the film, as by pivotally securing each gripping member to the end of an associated expansion arm and rotating the end of each expansion arm away from the center of the film while maintaining the gripping members equidistant from the center of the film. The expansion arms are uniformly rotated by a geared shaft powered by a drive mechanism that extends through the wall of an oven for coupling to an external motor.

Abstract: A non-porous coated PTFE graft includes a PTFE tube having a conventional porous inner cylindrical wall and a non-porous elastomeric coating applied over at least a portion of the outer cylindrical wall of the PTFE tube to render such portion of the outer cylindrical wall non-porous. The elastomeric coating is made of polyurethane or another biocompatible non-porous elastomer and precludes tissue ingrowth into the outer cylindrical wall, minimizes suture hole bleeding, and increases suture retention strength, while reducing the incidence of serous weepage. The elastomeric coating is preferably applied by mounting the PTFE tube upon a mandrel of like diameter and either dip coating or spray coating all, or selected portions, of the PTFE tube with liquified polyurethane. After the polyurethane coating is completely dried, the non-porous vascular graft is removed form the mandrel and is ready for use.

Abstract: A vascular patch for closing an incision in a blood vessel includes a base layer of expanded polytetrafluoroethylene (PTFE) having an outer coating of an elastomeric, biocompatible material such as polyurethane to minimize suture hole bleeding. Suture guidelines are formed upon the ablumenal side of the PTFE base layer prior to application of the elastomeric coating to facilitate proper and consistent placement of sutures. A colorant is added to the elastomeric coating to identify the ablumenal side of the vascular patch. The vascular patch is made by mounting an expanded PTFE tube upon a mandrel and applying a water based PTFE ink as a helical stripe about the outer surface of the PTFE tube to form the suture guidelines. The striped PTFE tube is then dip-coated or spray-coated with the elastomeric coating to which the colorant has been added. The PTFE tube is slit to form a flat sheet from which vascular patches are cut.

Abstract: A vascular patch for closing an incision in a blood vessel includes a base layer of expanded polytetrafluoroethylene (PTFE) having an outer coating of an elastomeric, biocompatible material such as polyurethane to minimize suture hole bleeding. Suture guidelines are formed upon the ablumenal side of the PFTE base layer prior to application of the elastomeric coating to facilitate proper and consistent placement of sutures. A colorant is added to the elastomeric coating to identify the ablumenal side of the vascular patch. The vascular patch is made by mounting an expanded PTFE tube upon a mandrel and applying a water based PFTE ink as a helical stripe about the outer surface of the PTFE tube to form the suture guidelines. The striped PTFE tube is then dip-coated or spray-coated with the elastomeric coating to which the colorant has been added. The PTFE tube is slit to form a flat sheet from which vascular patches are cut.

Abstract: A longitudinally compliant PTFE graft is provided by compressing at least a portion of a porous PTFE tube along its longitudinal axis and coating at least the outer wall of the compressed portion of the PTFE tube with a biocompatible elastomer for allowing the compressed portion of the tube to be stretched along the longitudinal axis. The PTFE tube is compressed by pulling the tube over a cylindrical mandrel of like diameter and applying a compression force to the tube along its longitudinal axis. The compressed portion(s) is (are) secured against movement upon the mandrel, and a coating of liquified polyurethane or other biocompatible elastomer is then applied over at least the compressed portion(s) of the tube. The elastomeric coating may be applied by dip coating or spray coating techniques. After the elastomeric coating has dried, the completed graft is removed from the mandrel.