The effects of assisted circulation by intraaortic balloon pumping and shunting of the left ventricle on myocardial damage after coronary artery ligation in dogs.

The purpose of this study is to determine the effects of different kinds of assisted circulation (AC) on the intensity of ischemic and necrotic processes in experimental myocardial infarction in dogs. Three types of experiments were carried out. In the first group, the infarction was modelled by surgical ligation of a branch of the descending artery. In the second group, AC by intraaortic balloon counterpulsation was started 15min after coronary occlusion and lasted for 2 hours. In the third group, AC was carried out by means of left ventricular drainage with transaortic insertion of a catheter, and a subsequent forcing of the blood into the femoral artery. During the experiment, 10 piecardial leads were recorded tandhe number of points registering a considerable displacement of seTgment S (nST) as well as the total displacement of segment ST (ΣST) were analysed. The size of the necrotic zone in the myocardial wall was identified macroscopically.The results testify to the favourable effects of both methods of AC on the intensity of destructive myocardial processes. The effect on ST was recorded soon after the beginning of AC. The effect on ΣST was less pronounced and was observed at a later stage (after 30-45min). In the histochemical investigation of the necrotic zone of the myocardial wall, the positive effects were more marked in the extracorporeal bypass of the left ventricle, which showed the size of myocardial infarction to be much smaller (p<0.05) than in the group with intraaortic balloon pumping. These experimental data are indicative of a significant positive effects of AC. In particular, shunting of the left ventricle caused a marked decrease in myocardial necrosis.