Myocardial lesions in hemorrhagic hypotension.

The myocardial alterations were investigated in dogs after hemorrhagic hypotension. Development of metabolic acidosis with increased lactate concentration was observed in all cases. Focal hemorrhages and hypoxic changes developed in the subendocarial region. Typical so-called zonal lesions were demonstrable in the mural myocardium of both ventricles. The hypoxia, increased level of catecholamines, metabolic disturbances, and probably cardiotoxic products may play a role in the pathomechanism. The alterations which are potentially reversible are transformed into irreversible damage only in most severe cases. The necrosis is of hypercontraction type, and is associated with rapid calcification and mononuclear cell infiltration. The morphologic changes may explain the circulatory disturbances of cardiac origin and may represent the basis of development of the low cardiac output syndrome in hemorrhagic shock.