Nonthrombogenic small-caliber human umbilical vein vascular prosthesis.

The present investigation demonstrates covalent binding of heparin with carbodiimide to ammonium hydroxide-treated collagenous surfaces. Human umbilical vein grafts (HUVG) outperform carotid arteries of goat, porcine, and canine origin in both heparin loading and stability of the immobilized heparin preparation. The average heparin loading on the untreated carotid arteries and HUVGs and ammonium hydroxide-treated HUVGs were 18, 27, and 31.5 micrograms/cm2, respectively. There was negligible loss of heparin activity under in vitro and in vivo conditions. In vitro studies demonstrate that heparin-bound HUVGs discourage platelet adhesion and subsequent fibrin clot formation. In vivo studies with heparin-bound HUVGs show a significant increase in thrombus-free surface compared with control grafts. Heparin-bound HUVGs also show an enhanced patency rate in the two sets of protocols tested--one lasting for 3 in vivo days (seven grafts) and the other lasting for 7 (15 grafts) in vivo days. The studies conducted so far demonstrate the promise of developing a nonthrombogenic small-caliber HUVG prosthesis.