Increased muscularity of the pylmonary circulation in victims of sudden infant death syndrome.

It has recently become apparent that some victims of sudden infant death syndrome (SIDS) are chronically hypoxemic before death. In this study, the structural alterations in the pulmonary circulation of 15 victims of SIDS were examined using precise quantitative morphometric techniques applied to the injected and inflated lung. Increased muscularity of the pulmonary circulation has been demonstrated, as evidenced by the extension of muscle into arteries not usually muscularized during the first year of life, and by an increased thickness of the medial wall in some patients. This confirms the findings of Naeye and further justifies the shift of investigative efforts from the events immediately surrounding death to a search for chronic abnormalities.