Abstract
The effect of coronary reperfusion on evolving myocardial infarction was examined in 16 conscious dogs. Coronary arterial occlusion was produced by inflating an exteriorized balloon cuff, and reperfusion was initiated 5 hours later by deflating the cuff. Infarct size calculated from 24 hour serial serum creatine phosphokinase (CPK) values was compared to infarct size predicted from log normal curves best fit to initial 5 hour serial CPK changes. With sustained occlusion, predicted and observed infarct size correlated closely (r = 0.94, no. = 11). Reperfusion produced two disparate effects. In nine dogs, observed infarct size was less than predicted, reflecting 42 ± 6 percent (standard error) salvage of myocardium. In seven dogs, observed infarct size exceeded predicted size by more than 100 percent. Thus, reperfusion resulted in extension of myocardial infarction in 44 percent of the animals. Extension of infarction was associated with myocardial hemorrhage. Hemoglobin content in biopsy specimens from the center of the infarct was 10 times greater in the animals with extension of infarction than in those with myocardial salvage. Thus, reperfusion is not without hazard during evolving infarction in the conscious dog; although it frequently diminishes ischemic injury, it may precipitate myocardial hemorrhage and extension of infarction. © 1974.