Hemorrhage from myocardial revascularization.

Four groups of 12 dogs each had ligation of the left anterior descending coronary artery (LAD) with subsequent release of the ligature and confirmed reperfusion. After 24 hours of reperfusion, the hearts were removed. sliced at 1 cm intervals along the transverse axis, and stained with triphenyltetrazolium chloride. Measurements of the infarct size as a percentage of the left ventricular area (I) and of hemorrhage as a percentage of infarct size (H) were made. The duration of ligation was 3 hours in Group 1, 6 hours in Group II, 18 hours in Group III, and 30 hours in Group IV. No significant difference in infarct size was found among the groups. Percent hemorrhage was 25.2% of infarct area in Group I, 28.3% in Group II, 18.1% in Group II, and 0.7% in Group IV. If reperfusion hemorrhage into an acute myocardial infarct is deleterious, these data suggest than danger to be decreased at 18 hours and absent at 30 hours after acute coronary occlusion.