Wall motion and metabolic changes after coronary occlusion and reperfusion

Experiments were conducted in open-chest pigs in which experimental myocardial ischemia was produced. Two groups of animals were evaluated: (1) those with short episodes of coronary occlusion and reperfusion, and (2) those with an initially longer period of occlusion (equal to the sum of the short multiple occlusions) and reperfusion. Indices of myocardial wall motion as determined by echocardiogram, of energy production as measured by mitochondrial oxidative phosphorylation, and of cellular membrane integrity as measured by calcium uptake by sarcoplasmic reticulum vesicles and calcium content of tissue and mitochondria were obtained. Our observation revealed better myocardial preservation in the group with brief periods of occlusion and reperfusion than those with a sustained period of ischemia followed by reperfusion. The concept that myocardium is less well preserved due to reperfusion damage by intermittent aortic cross-clamping or intermittent coronary perfusion during open heart surgery compared to uninterrupted cardiac arrest needs to be reexamined in light of the data presented and investigated in the hypothermic, cardioplegia model.