Cardiac lesions in sudden infant death syndrome.

Sequential morphological changes as found in the hearts of 250 sudden infant death syndrome (SIDS) infants are described. Detailed examination of macroscopic and microscopic lesions reveal that all SIDS infants had identifiable lesions at the time of their death. The lesions can best be described as selective focal anoxic muscle fibre necrosis at chronologically different developmental stages. The extent of these lesions vary markedly from case to case, from a minimal muscle fibre eosinophilia through contraction band formation, myocytolysis, stromal condensation to scar formation. The morphological variations in the lesions amongst individual cases can be interpreted as relating to the time interval of the development of the lesions. The intramural and coronary arteries in some cases are also affected showing intimal hyperplasia. Although these sequential morphological aberrations are not specific and typical to SIDS infants only, they were present in all SIDS infants in this series.