title: Improvements in GORE-TEX vascular graft performance by Carmeda BioActive surface heparin immobilization.
abstract: OBJECTIVE
  a performance improvement in small-diameter bypass grafts remains a clinical objective. The purpose of the present investigation was to evaluate the potential of enhancing the thromboresistance of ePTFE grafts using a bioactive heparinized graft luminal surface in a canine model.
  
  
  METHODS
  this study investigated the utility of heparin immobilization onto expanded polytetrafluoroethylene using Carmeda BioActive Surface technology (CBAS-ePTFE) as a means of improving vascular graft thromboresistance. Graft luminal surfaces were covered uniformly with the stably bound, end-point immobilized heparin.
  
  
  RESULTS
  acute canine (5 greyhounds) interposition experiments comparing CBAS-ePTFE grafts to control ePTFE grafts showed that CBAS-ePTFE grafts remained patent and had significantly greater thrombus-free luminal surface (p<0.05). In a chronic canine (16 greyhounds) interposition experiment, significantly improved patency (p<0.05) was observed with CBAS-ePTFE grafts compared to controls. Long-term in vivo heparin bioactivity was demonstrated on CBAS-ePTFE grafts explanted between 1 and 12 weeks. On all CBAS-ePTFE grafts, heparin activity levels ranged from 15-25pmol/cm(2) and did not differ significantly (p>0.05).
  
  
  CONCLUSIONS
  these results support the conclusion that a stable, CBAS-ePTFE surface provides improved thromboresistance and improved patency in canine interposition models. Maintenance of heparin catalytic activity on the graft surface in vivo likely contributes to this outcome and holds promise for the utility of this graft surface for clinical applications.
authors.affiliation: W. L. Gore & Associates, Inc. 3250 West Kiltie Lane, P.O. Box 300, Flagstaff, AZ 86002-0300, USA.
authors.forename: P C
authors.initials: PC
authors.lastname: Begovac
authors.forename: R C
authors.initials: RC
authors.lastname: Thomson
authors.forename: J L
authors.initials: JL
authors.lastname: Fisher
authors.forename: A
authors.initials: A
authors.lastname: Hughson
authors.forename: A
authors.initials: A
authors.lastname: Gällhagen
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000925:Anticoagulants / Q000494:pharmacology*; D001807:Blood Vessel Prosthesis; D020099:Coated Materials, Biocompatible; D004285:Dogs; D006083:Graft Occlusion, Vascular / Q000209:etiology / Q000517:prevention & control*; D006493:Heparin / Q000494:pharmacology*; D008855:Microscopy, Electron, Scanning; D011138:Polytetrafluoroethylene; D013499:Surface Properties; D014654:Vascular Patency
chemical_list: D000925:Anticoagulants; D020099:Coated Materials, Biocompatible; D011138:Polytetrafluoroethylene; D006493:Heparin