Nutrient myocardial blood flow in experimental myocardial ischemia. Effects of intraaortic balloon counterpulsation and coronary reperfusion.

This experimental study was designed to evaluate the effect of intraaortic balloon pumping (IABP) upon nutrient myocardial blood flow (NMBF) following acute myocardial ischemia in dogs, but also to determine whether IABP improves NMBF following revascularization. Localized myocardial ischemia was produced by ligation of one or two small branches of the circumflex coronary artery combined with a three hour snare occlusion of the left anterior descending coronary artery distal to the first septal branch. NMBF was measured by NaI131 washout at three points corresponding to the peripheral, intermediate, and central zones of the infarct. Occlusion of the coronary arteries reduced NMBF. Release of occlusion after three hours, or the equivalent of coronary artery revascularization, increased NMBF but did not restore it to control levels. The increase in flow was more marked in the peripheral zones of ischemia. IABP increased NMBF significantly both during and after release of occlusion. The effect was sustained after cessation of IABP only when the latter was maintained during the period of reperfusion. The results indicate that NMBF, defined by washout of a locally injected tracer, was improved by both IABP and reperfusion. The beneficial effect was maximal when the two techniques were combined.