Determinants of arrhythmic death during coronary artery reperfusion: effect of perfusion bed size.

To further our understanding of the factors determining the consequences of transient episodes of ischemia, we studied the influence of the size of the ischemic bed on the incidence of ventricular fibrillation (VF). The circumflex coronary artery (CFX) was occluded at various locations in 19 dogs. After 20 minutes of occlusion followed by 10 minutes of reperfusion the dogs were killed. The portion of the left ventricle (LV) at risk of infarcting (R/LV) was defined as the region supplied by the occluded CFX and determined by simultaneous perfusion of the CFX with saline solution, just beyond the occlusion site, and of the aorta with Evan's blue. Bread loaf slices of the heart were photographed and projected, and the normal (blue) and risk regions (unstained) traced. The product of area and slice weight yielded mass of normal and risk regions. The R/LV of dogs that died of reperfusion VF (n = 6) was 42.3 +/- 5.0%, larger (p less than 0.001) than R/LV in all surviving dogs (n = 13), 24.2 +/- 9.4%. Twelve of the 13 survivors had R/LV less than 35%, whereas all dogs that died had R/LV greater than 35% (p = 0.0005). As is true for VF occurring during coronary artery occlusion, the incidence of reperfusion VF is related to the size of the ischemic insult.