Large fetal pulmonary arteriovenous fistula: impact on pulmonary development.

A case report of a patient with a large pulmonary arteriovenous fistula and valvar pulmonary stenosis is presented. The fistula was diagnosed prenatally and its effect on in utero cardiovascular growth and development documented. Due to concerns about massive intrapulmonary shunting potentially causing profound cyanosis after delivery, an EXIT (EX-utero Intrapartum Treatment) procedure was used to transfer the infant from placental to extracorporeal membrane oxygenation (ECMO) support. Severe pulmonary microvascular disease resulted in prohibitive pulmonary hypertension despite surgical ligation of the fistula. Prenatal and postnatal hemodynamic assessments of the fistula are presented and are compared to the pathologic findings.