Platelet function is altered by autogenous vein grafts in the early postoperative months

A new animal model was used to study the effect of autogenous vein grafts on platelet function and to follow the time course of any changes. Reversed external jugular vein was grafted to the ipsilateral carotid artery in lop-eared rabbits. The platelet activation index (PAI), a measure of platelet responsiveness to adenosine diphosphate, was used to measure the effect of the graft on platelets at set postoperative times and the results compared with pre-operative values. There was a statistically significant increase in PAI in samples taken from the central ear artery at 1 week (P less than 0.005), 1 month (P less than 0.005) and 2 months (P less than 0.05) after operation, but not at 4, 6 and 8 months. In animals killed 1 week and 1 month after operation, platelets were shown to be activated following a single passage across the graft. Platelets that have been activated by the graft may in turn be involved in the process of intimal hyperplasia in the graft wall. Our results suggest that modification of the behaviour of activated platelets by drug intervention may only be required during the early postoperative months.