Pulmonary arteriolar muscle thickening in sudden infant death syndrome.

Pulmonary arteriolar thickening in sudden infant death syndrome has been repeatedly reported but this finding has been challenged. We report a case of a previously healthy 23-day-old infant girl who was witnessed by her parents to die suddenly and unexpectedly. During a routine bottle-feeding, she suddenly began to cry loudly and her face became deep-red and then pale. She became limp and began to gasp. Resuscitation efforts were to no avail. The post-mortem examination, including toxicological studies, screening for inborn errors of metabolism and genetic studies for prolonged Qt syndrome, failed to reveal the cause of death. A more focused study of the lungs showed extensive pulmonary arteriolar thickening. The events in the sudden death of this infant are remarkably similar to deaths in infants with various disorders associated with pulmonary arteriolar thickening. We suggest that this vascular abnormality and associated pulmonary hypertension played a critical role in this infant's death.