[Myocardial morphology in fibrillation and defibrillation of the heart ventricles].

The morphology of the contractile myocardium was studied experimentally in fibrillation and defibrillation of the ventricles on 30 rabbits. Morphology of the contractile myocardium appears as vacuolated dystrophy of the cardiomyocytes, destruction of mitochondria and contracture lesions of the myofibrils. The latter with progressing fibrillation become irreversible. Myocardial changes are related both to the mechanical lesions of cardiomyocytes and the haemodynamic disorders, developing as a result of ventricular fibrillation, which leads to marked myocardial hypoxia. The changes in the microcirculatory bed contribute to the development of the latter. Hyperfunction of the intracellular structures, especially of mitochondria and myofibrils, taking place under unfavourable conditions leads to a rapid energy depletion, which is one of the main causes of development of the acute cardiac insufficiency in this type of arrhythmias. Studies of cardiac defibrillation enabled one to elicit the dynamics of morphological changes, appearing in the myocardium as related to the duration of ventricular fibrillation.