[Ultrastructure of the peri-infarcted zone of the myocardium].

Light, electron and polarization microscopy techniques were employed to examine the myocardium in 26 dogs under experimental occlusion of the anterior descending branch of the left coronary artery in its middle third from 2 hours to 1 month. The periinfarcted zone is thought to be adjacent to the zones of ischemia and myocardial infarction and to be represented by a zone of lipid infiltration of cardiomyocytes in which the contraction lesions and foci of intracellular myocytolysis are demonstrable. It is shown that the increasing of the volume of the myocardial necrotic tissue under coronary occlusion is accounted for by progressive microthrombosis leading to circulatory disorders and necrosis of lipid infiltrated cardiomyocytes in the periinfarcted zone. The pathological intracellular regeneration in the atrophied cardiomyocytes of the periinfarcted zone was discovered to contribute to hypertrophy of myocytes with abnormal myofibril orientation. Studies of the periinfarcted zone hold promise from the standpoint of influencing the metabolism and intracellular regeneration of this zone cardiomyocytes, that mainly determines the reparative regeneration of the myocardium in ischemic necrosis.