Movement of necrotic wavefront after coronary artery occlusion in rabbit

Movement of the necrotic wavefront after coronary artery occlusion (CAO) was defined in rabbits by comparing transient CAO (15, 30, or 60 min) and reperfusion to permanent CAO (n = 5-9/group). At 24 h after CAO the area of necrosis was determined by nitro-blue tetrazolium staining, and the transmural and circumferential extent of necrosis was evaluated at four levels from ligation to apex. Infarct size after permanent CAO for 24 h was 27 +/- 2 (SE) % of the left ventricle. Reperfusion at 60, 30, or 15 min after CAO reduced the infarct size to 24 +/- 3 (P = NS vs. 24 h), 14 +/- 2, and 8 +/- 1% (P less than 0.05 vs. 60 min), respectively. Reperfusion at 15 and 30 min after CAO decreased transmural extent by 49 and 38% (P less than 0.001 vs. 24 h), whereas the circumferential extent was reduced by only 10 and 12%, respectively (P = NS). After 60 min of CAO, reperfusion did not significantly reduce either transmural or circumferential necrosis. Thus early reperfusion reduced infarct size by converting potentially transmural infarcts into subendocardial infarcts but did not significantly reduce the lateral or circumferential extent of necrosis.