Intravenous Trypsin in Experimental Myocardial Infarction

The possibility of using intravenous proteolytic agents in the treatment of acute myocardial infarction has been studied. The coronary arteries of closed-chest dogs were embolized with small repetitive doses of fibrin clots until definite electrocardiographic evidence of myocardial injury which persisted for at least two hours was observed. The treated animals were given up to six intravenous infusions of 250,000 Armour units of trypsin in 250 ml. saline over a period of eight days, and the survivors were sacrificed on the ninth day. The control animals received no trypsin. These studies showed that trypsin caused dissolution of the host thrombus which formed around the fibrin clots, without damage to the infarcted tissue; that the coronary vessels were recanalized; that the extent of infarction was decreased; and that the electrocardiographic changes were improved and the mortality was reduced.