[Ultrastructure of cardiomyocytes during mitral valve replacement in non-perfusion hypothermia]

The ultrastructure of biopsy specimens obtained from the left ventricle was examined at varying stages of mitral valve replacement under non-perfusion hypothermal protection (at 27-28 degrees C). In patients with clinical stage IV mitral incompetence, cardiomyocytes were shown to combine signs of marked hypertrophy and decompensation. Despite the initial plastic muscular cell incompetence, there are only small changes in their ultrastructure and myofibril contracture in the pre-occlusion period, which subside by the end of long-term (up to 37 min) occlusions. For the myocardium, reperfusion is the most damaging, but the damages, though widely diverse, are regarded mainly as moderate and reversible. Over again the electron microscopic finding provide good evidence for the feasibility of performing complicated cardiac surgeries with prolonged reversible exclusion of blood circulation under non-perfusion hypothermia.