STABILITY OF THROMBOSIS INDUCED BY ELECTROCOAGULATION OF RAT MIDDLE CEREBRAL-ARTERY

Background and Purpose Although it is often assumed in experimental st roke studies that cautery-induced occlusion is permanent, surgeons com monly expect cauterized vessels to recanalize spontaneously. We used t he rat middle cerebral artery to determine if electrocoagulation would produce a permanent occlusion in this preparation. Methods and Result s A standard bipolar coagulator, calibrated to determine actual power output, was adjusted to induce platelet aggregation in the middle cere bral artery of anesthetized Sprague-Dawley rats without inducing bleed ing through the arterial wall. A reliable temporary thrombosis was ind uced by a Malls Bipolar Coagulator set to deliver 10 bursts of 1.5 sec onds each at a rate of 24 min(-1) and a power setting of 3 W. This thr ombus was responsive to the antithrombotic agent flunarizine. An appar ently permanent occlusion was produced by 30 bursts at 3 W followed by 20 bursts at 5 W. To our surprise, seven of seven such occlusions rec analized spontaneously within 4 hours. Conclusions The electrocoagulat ion process commonly used in experimental stroke studies may produce o nly a temporary occlusion of the rat middle cerebral artery.