Carotid endarterectomy. The timing of perioperative antiplatelet therapy by indium 111 labelled platelets study in canines.

Bilateral carotid endarterectomy (CEA) was performed in a series of 16 dogs, one of the arteriotomies being closed by direct suture and the other with an autologous vein patch. Platelets obtained at the induction of the anaesthetic were labelled with Indium 111 Oxine and subsequently re-infused prior to restoration of blood flow. Post-operative sequential platelet counts using a Selo CSZ counter were undertaken, which demonstrated a substantial rise at the sites of CEA. These counts rose to peak levels between 7-88 minutes after declamping with a median peak time of 20 minutes. Continued high levels of labelled platelet accumulation persisted for 48-96 hours following CEA and in some instances persisted for three weeks. These studies suggest that antiplatelet agents should therefore be active when carotid declamping occurs and administered for at least three weeks following CEA.