Indications for and limitations of coronary thrombolysis

Experimental studies in dogs with coronary thrombi induced by copper wire confirmed the optimal method of intracoronary thrombolysis, and showed that a high-dose, brief intravenous infusion of urokinase can lead to recanalization. The thrombolytic effects of intracoronary thrombolysin at a rate of 50 IU/kg over 10 minutes are similar to the effects of intracoronary urokinase at a rate 500 IU/kg over 20 minutes. Overall reperfusion rates of 83-86% have been achieved. These results indicate that the thrombolytic effect of thrombolysin is 20 times stronger than that of urokinase. The effect of a brief intravenous infusion of urokinase was less than that of intracoronary urokinase. The reperfusion rate in the same experimental model was 40%. Later, a clinical trial of intracoronary urokinase was performed in 47 patients with acute myocardial infarction who were admitted within 12 hours of the onset of symptoms. In 25 of 33 (75.8%) patients with complete occlusion, selective or ostial infusion of urokinase 500 IU/kg over 20 minutes was successful. When given intravenously, recanalization was achieved in 11 of 15 (73%) patients with complete occlusion who were admitted within 6 hours. Both reperfusion rates were similar except for dosage and the duration of infusion.