[Direct continuous observation of in situ thrombolysis in the cerebral embolic model of rabbits].

To investigate the occurrence of cerebral embolism, a rabbit embolic stroke model was used for the continuous monitoring of the change of the thrombus. Red thrombus was directly injected into the internal carotid artery via the catheter inserted into the external carotid artery. The migration of the thrombus into the middle cerebral artery was judged as the completion of an embolism. The change of the thrombus and its movement was observed for a period of two hours. The experimental group received recombinant tissue plasminogen activator (TPA) for the thrombolysis while the control group received a saline solution for 30 minutes. The thrombus in the middle cerebral artery was continuously observed for two and a half hours. 1. There was a spontaneous movement of the thrombus during the first two hours in six out of 18 cases. One case showed a spontaneous regression in size at the migration site. 2. White thrombus formation occurred around the thrombus in eight out of 18 cases. 3. In the TPA injected group, thrombolysis was observed in nine out of ten rabbits. The accompanied white thrombus was also found to be degraded. However, after the TPA injection, white thrombus was newly formed during the lysis of red thrombus. 4. In the saline solution injected control group, only partial recanalization occurred in three out of eight rabbits. There was no white thrombus formation in the control group. 5. There was no significant difference in the degree of Evans blue exudation between these two groups. Secondary activation of the platelet function easily occurred by the change of the blood flow during thrombus migration and also thrombolysis. In conclusion, thrombolysis therapy may be more effective when TPA is administered in conjunction with the suppression of platelet function.