Patents Assigned to Impra, Inc.
  • Patent number: 5468138
    Abstract: An apparatus for expanding polymer films such as PTFE films includes gripping the unexpanded film about its periphery with a number of symmetrically disposed gripping members each equidistant from the center of the 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. Also disclosed is an expanded PTFE film made in accordance with such process.
    Type: Grant
    Filed: March 29, 1994
    Date of Patent: November 21, 1995
    Assignee: IMPRA, Inc.
    Inventors: Charles F. Bosse, Rajagopal R. Kowligi
  • Patent number: 5466509
    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.
    Type: Grant
    Filed: January 15, 1993
    Date of Patent: November 14, 1995
    Assignee: IMPRA, Inc.
    Inventors: Rajagopal R. Kowligi, John M. Bibeau, Howard H. Taylor
  • Patent number: 5453235
    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..
    Type: Grant
    Filed: January 29, 1993
    Date of Patent: September 26, 1995
    Assignee: Impra, Inc.
    Inventors: Robert W. Calcote, Rajagopal R. Kowligi, Stacy Wollner
  • Patent number: 5321109
    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.
    Type: Grant
    Filed: November 17, 1992
    Date of Patent: June 14, 1994
    Assignee: Impra, Inc.
    Inventors: Charles F. Bosse, Rajagopal R. Kowligi
  • Patent number: 5246452
    Abstract: A porous graft is provided with a non-porous coating or sheath which does not adhere to the graft. After the graft is implanted into the patient, circulation is restored through the graft. The sheath is left in place temporarily while blood works its way through the wall of the porous graft to the non-porous sheath, where it is prevented from leaking. Clots form in the graft, sealing it. After a few minutes, the sheath is removed. The graft or the inside surface of the sheath can be pre-treated with a coagulant to accelerate clotting. The sheath is applied to the graft as a coating, e.g. by dipping or spraying, or as a separate sleeve, e.g. heat-shrinkable tubing. The sheath can be removed by cutting. Preferably, the sheath incorporates a string, strip, or ribbon of material which is attached to the sheath. For removal, the string is pulled, tearing the sheath which is removed with the string.
    Type: Grant
    Filed: April 13, 1992
    Date of Patent: September 21, 1993
    Assignee: Impra, Inc.
    Inventor: Joseph B. Sinnott
  • Patent number: 5152782
    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.
    Type: Grant
    Filed: May 26, 1989
    Date of Patent: October 6, 1992
    Assignee: Impra, Inc.
    Inventors: Rajagopal R. Kowligi, Robert C. Farnan, William M. Colone, Linda V. Della Corna, Joseph B. Sinnott
  • Patent number: 5104400
    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.
    Type: Grant
    Filed: August 28, 1991
    Date of Patent: April 14, 1992
    Assignee: Impra, Inc.
    Inventors: Ramon Berguer, Robert C. Farnan, William M. Colone, Rajagopal R. Kowligi, Linda V. Della Corna, Joseph B. Sinnott
  • Patent number: 5100422
    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.
    Type: Grant
    Filed: May 26, 1989
    Date of Patent: March 31, 1992
    Assignee: Impra, Inc.
    Inventors: Ramon Berguer, Robert C. Farnan, William M. Colone, Rajagopal R. Kowligi, Linda V. Della Corna, Joseph B. Sinnott
  • Patent number: 4955899
    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.
    Type: Grant
    Filed: May 26, 1989
    Date of Patent: September 11, 1990
    Assignee: Impra, Inc.
    Inventors: Linda V. Della Corna, Robert C. Farnan, William M. Colone, Rajagopal R. Kowligi
  • Patent number: 4822341
    Abstract: A vascular access fistula includes a smooth, continuous PTFE tube having a hard sintered tube section integrally joined at its opposing ends with expanded PTFE tube sections. Inlet and outlet access port holes are formed in the hard sintered tube section to provide acute access to the fistula. A port collar surrounds the hard sintered tube section to facilitate the attachment of dual lumen tubing thereto. Following implantation of the access fistula, the dual lumen tubing temporarily extends through the skin to provide acute access while the access fistula heals. The port collar houses a slide valve which selectively couples the inlet and outlet access port holes to the dual lumen tubing for acute access. After the access fistula has healed, the slide valve is closed, the dual lumen tubing is cut off from the port collar, and chronic vascular access is provided by percutaneous cannulation of the implanted PTFE tube.
    Type: Grant
    Filed: November 20, 1987
    Date of Patent: April 18, 1989
    Assignee: Impra, Inc.
    Inventor: William M. Colone