Pulmonary vasculature changes associated with idiopathic closure of the ductus arteriosus and hydrops fetalis.

Antenatal closure of the ductus arteriosus has been considered as a potential risk factor for the development of hydrops fetalis and persistent fetal circulation of the newborn. We present an infant with antenatal ductal closure who had not received prenatal prostaglandin synthetase inhibitors. The pulmonary vascular morphological findings are described and compared to three additional infants in whom the ductus arteriosus was known to be patent; one with neonatal sepsis and two others with hydrops fetalis. The infants with fetal hydrops, regardless of etiology, had increased muscularization of the acinar pulmonary arteries. In addition, the infant with antenatal closure of the ductus arteriosus also had both a significant decrease in preacinar arterial external diameter and an increase in medial wall thickness. Antenatal closure of the ductus arteriosus appears to enhance in utero pulmonary blood flow and this may be the cause of pulmonary vascular remodeling.