In vitro andin vivo studies of heparinized-collageno-elastic tubes

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Abstract
Heparin was covalently coupled to collageno‐elastic grafts (CET) derived from lamb carotid arteries, by using the crosslinking agent 1‐ethyl‐3 (3‐dimethylaminopropyl) carbodiimide (EDC). The collagenous grafts were pretreated with various aminating agents in order to enhance the number of available binding sites on the collagen surface. By varying the EDC/heparin weight ratio, the pH of the immobilization media, and the pretreatment agent, a global search pattern maximized heparin loading at 3.90 ± 0.36 USP heparin/cm2 collagenous graft surface when the EDC/heparin ratio was 2:1 at a pH of 1.5 with 1 M hydroxylamine sulfate as the pretreatment agent. Heparinized CETs were superior to nonheparinized CETs by exhibiting both enhanced antiplatelet activity in using an in vitro differential recirculation reactor with chromium‐51 tagged platelets and enhanced patency when interposed in canine carotid arteries. Both antiplatelet activity and patency duration for heparinized CETs were independent of heparin loading.