PERSISTENT FETAL CIRCULATION - NEWLY RECOGNIZED STRUCTURAL FEATURES

Infants (3) died with pulmonary hypertension of unknown cause during the first 3 mo. of life. Their lungs were examined using quantitative morphologic techniques. In all 3 cases the intra-acinar pulmonary arteries were more muscular than normal, as shown both by an increase in thickness of the muscle coat in arteries which are normally muscular, and by extension of muscle into smaller and more peripheral intra-acinar arteries not normally muscular at this age. Persistent pulmonary hypertension of the newborn infant is, in some infants, due to a structural abnormality of the pulmonary circulation which is present at birth.