Determination of experimental myocardial infarct size.

Myocardial infarction was produced in anesthetized dogs by a 2-hr occlusion and 30-min reperfusion of the left anterior descending cornary artery. A balloon-reservoir perfusion system was used for reperfusion and delineation of perfusion bed size (area at risk) with Patent blue dye. Infarct mass was determined by a histochemical staining technique with triphenyl tetrazolium chloride. Regional myocardial perfusion in infarcted, ischemic, and normal regions was measured with radioactive microspheres. Infarct size was 8.5 +/- 1.6 g and accounted for irreversible damage in 9.2 +/- 1.9% and 32.5 +/- 4.8% of the left ventricle and area at risk, respectively. Regional myocardial blood flow within infarcted regions was constant over the 2-hr occlusion period (0.10 +/- 0.03 to 0.11 +/- 0.02 ml/min/g). Following reperfusion, these areas demonstrated significantly lower flow than did normal regions, Ischemic but noninfarcted tissue also had no change in flow over the occlusion period, but flow returned to normal following reperfusion. This study describes reliable methodology for production and determination of infarct size with simultaneous measurement of several factors involved in the relative extent of irreversible tissue damage.