Effect of Intra-arterial Antifibrinolytic Agents on Autologous Arterial Emboli in the Cerebral Circulation of Rabbits

We conducted a randomized, blinded controlled trial to test the efficacy of fibrinolytic therapy with tissue plasminogen activator and urokinase in the treatment of acute embolic stroke. Embolic stroke was simulated in rabbits by injecting three 0.5x0.5 mm fragments of autologous arterial thrombus harvested from a traumatized auricular artery. Thirty minutes after embolization the rabbits were blindly treated with tissue plasminogen activator (n=21), urokinase («=20), or 0.9% saline (n=20). At 6 hours the rabbits were sacrificed, and the cerebral vasculature was inspected for the location and number of emboli. The brain was then cut into 0.5-cm-thick coronal sections and stained with triphenyltetrazolium chloride to define areas of infarction. Treatment with either tissue plasminogen activator or urokinase significantly reduced the number of emboli present in the cerebral circulation (p<0.05). The area of ischemic injury was also significantly reduced (/><0.05) by acute fibrinolytic therapy with either tissue plasminogen activator or urokinase. However, only treatment with tissue plasminogen activator significantly reduced (/><0.05) the incidence of infarction. There was no evidence of intracerebral hemorrhage in any rabbit. Early fibrinolytic therapy improved outcome in this model of acute embolic stroke. (Stroke 1990;21:1594-1599)