[Hemodynamic and ultrastructural changes in the acute stage of myocardial ischemia (an experimental study)]

The results of experiments on 38 dogs with acute myocardial ischemia are discussed. Hemodhynamics and contractile function of the myocardium were studied and the findings were compared with the data of myocardial structure in different time intervals. The authors claim that one of the first signs of myocardial contractile insufficiency is a change in the rate of myocardial contractility which becomes manifest against the background of disorders of rhythm. Electron microscopy at this moment is characterized by thickening of Z-disks. Before the onset of fibrillation the geometry of the cardiac ventricles changes, the ejection fraction decreases by 53%. The ultrastructure of the myocardium in this period is marked by stepped Z-disks and extensive damage to the mitochondrial cristae.