Cardiac pathology associated with high sustained +Gz: II. Stress cardiomyopathy.

The myocardial pathology of 14 pigs exposed to HSGz stress of 9 and 15, or 3, 7, and 9 Gz was studied; six control pigs were used as comparisons. Four pigs received propranolol prior to centrifugation and four pigs received atropine. Hearts were studied by light and electron microscopy. Myocardium from stressed pigs showed myofibrillar degeneration, pooling of mitochondria, and cell death. Lesions occurred in random cells of the subendocardium and papillary muscles. Purkinje fibers were also involved. Pretreatment with atropine increased the number of dead cells found and propranolol increased the number of cells showing myofibrillar degeneration. It is postulated that this is a pluricausal cardiomyopathy similar to several experimental conditions. Significance to aerospace medicine is briefly discussed.