Prenatal identification of the pulmonary arterial supply in tetralogy of Fallot with pulmonary atresia

To define the patterns of flow of blood to the lungs in fetuses with tetralogy of Fallot and pulmonary atresia. In this condition, supply of blood to the lungs is provided via an arterial duct or systemic-to-pulmonary collateral arteries, or very rarely through other conduits such as coronary arterial fistulas or an aortopulmonary window. The intrapericardial pulmonary arteries vary in size, and may be absent. These variables influence the prognosis and management. We carried out a retrospective review of cases from a tertiary service for fetal cardiology, identifying all cases of tetralogy of Fallot with pulmonary atresia diagnosed antenatally between January, 1997, and April, 2006. We established pre- and postnatal outcomes, and compared the prenatal diagnosis with postnatal or autopsy findings. Of 6587 fetuses scanned during this period, 11 were diagnosed as having tetralogy of Fallot with pulmonary atresia and no other cardiac defect. In 5, arterial flow to the lungs was via an arterial duct, and in the other 6, the main identified source of flow was systemic-to-pulmonary collateral arteries. Of the latter 6 pregnancies, 4 were terminated, along with 3 of the 5 with ductal supply. The presence of systemic-to-pulmonary collateral arteries was confirmed at postmortem examination in 3 instances, and in the two delivered neonates, in neither of whom was an infusion of prostaglandin commenced. The patterns of pulmonary flow can be identified prenatally in the setting of tetralogy with pulmonary atresia. Supply through systemic-to-pulmonary collateral arteries impacts on counselling, introducing uncertainty regarding postnatal surgical management.