Myofibrillar degeneration and necrosis of the visceral smooth musculature: an ischemic visceral myopathy.

Pathologic studies of the visceral smooth musculature in humans are scant despite the relatively frequent occurrence of alterations in these muscles in autopsy material. We investigated the different types of lesions of this musculature observed in various conditions associated with ischemia--acute tubular necrosis, congenital heart disease (low output syndrome due to open heart surgery), and necrotizing enterocolitis in premature babies. Control cases included normal rat tissue undergoing autolysis and rigor mortis and bowel resected from patients with ulcerative colitis and Hirschsprung's disease. Four histologically distinct lesions were present on hematoxylin--eosin staining in the ischemic group: contraction bands, wavy fibers, thick waves, and coagulation necrosis. These lesions were absent in the control groups. We conclude that myofibrillar degeneration and necrosis of the visceral musculature are common in disorders associated with visceral ischemia. These changes are not artifacts produced by autolysis, rigor mortis, or technical handling, nor are they induced by nonischemic inflammatory conditions. Catecholamines may play a role in their genesis.