MYOCARDIAL BLOOD-FLOW CONDITIONS AT RE-PERFUSION FOLLOWING ACUTE-ISCHEMIA

The effect of reperfusion upon distribution of radioactive microspheres in ischemic myocardium was investigated. Anesthetized cats (10) were given 15-.mu.m microspheres prior to left anterior coronary artery occlusion, at 1 h of occlusion and after 1 h of subsequent reperfusion. Preocclusion blood flow estimates were lower in tissue which were ischemic compared with nonischemic regions in the same heart (1.44 vs. 1.87 ml .times. min-1 .times. g-1, P < 0.001), corresponding to 23% apparent loss. Loss also occurred in ischemic right ventricular tissue (32%). In left ventricular ischemic endocardium, apparent loss was due to development of edema. Edema was also significant in epicardial ischemic tissue. Correction for edema eliminated 2/5 of the loss, while 3/4 was due to physical loss. Edema increased linearly with the level of reperfusion. During reperfusion, myocardical blood flow in previously ischemic tissue was inhomogeneously distributed and, on average, 28% lower than in nonischemic myocardium. The 15-.mu.m spheres appeared to pass through capillaries in the ischemic subepicardium, but this process was not enhanced by reperfusion.