Effect of intraaortic balloon counterpulsation (IABP) on myocardial infarct size and collateral flow in an experimental dog model.

To determine the influence of IABP on infarct size and collateral blood flow in each of 12 openchest anaesthetised mongrel dogs two small branches of the left coronary artery were occluded consecutively. The perfusion areas of both branches were comparable in size. IABP was started immediately before ligation of the first branch for a 90-min period followed by a reperfusion period of 90 min. Subsequently the second vessel was also occluded for 90 min as a control without IABP while myocardial oxygen consumption remained constant and was then reperfused. Infarct size was expressed as a percentage of the perfusion area. A difference in infarct size with and without IABP (18 +/- 17, 18 +/- 10% respectively) could not be observed. However a significant increase of collateral blood flow due to IABP in the subendocardial layer from 8.9 +/- 4.8 to 14.9 +/- 4.6 ml/100 g/min (p less than 0.05) was prevalent. In the subepicardial layer the augmentation from 23.7 +/- 19.9 to 26.9 +/- 15.2 was not significant. Thus, in spite of a small increase of collateral blood flow in the subendocardial layer of the ischemic myocardium the infarct size was not reduced by IABP in our dog model.