FIBRIN CONTENT OF CAROTID THROMBI ALTERS THE PRODUCTION OF EMBOLIC STROKE IN THE RAT

Background and Purpose Mechanical denudation of the endothelium of the carotid artery in animals produces a nonocclusive thrombus, but the b rains of these animals have not been examined for the presence of embo lic stroke. Methods The endothelium of the right carotid artery of 16 Wistar rats was denuded using a balloon catheter. Phosphotungstic acid hematoxylin (PTAH) staining and scanning electron micrographs of the nonocclusive thrombi in the carotid arteries were compared with those produced by photochemical methods, and brains were examined for infarc ts. Results Although nonocclusive thrombi were present in the carotid arteries of 4 of 4 rats killed at 4 hours and in 8 of 12 killed at 24 hours, neither cerebral infarcts nor emboli were seen in the 14 brains evaluated by light microscopy. PTAH demonstrated a high fibrin conten t in the thrombus produced by the endothelial denudation, with almost no fibrin seen in photochemically induced thrombi. Scanning electron m icroscopy confirmed dense networks of fibrin in the thrombi produced b y balloon denudation. Conclusions The composition of a nonocclusive th rombus may determine the embolic potential of this thrombus. A low fib rin content in a nonocclusive platelet thrombus may enhance the emboli c potential. This suggests that platelet inhibition may also be indica ted in patients with carotid artery disease who are being treated with anticoagulant.