Tetralogy of Fallot: prenatal diagnosis and postnatal survival

To correlate prenatal echocardiographic findings with infant outcome in a large screening population affected by tetralogy of Fallot.

Inclusion criteria required confirmed postnatal cardiac diagnosis, at least one fetal ultrasound examination with satisfactory heart visualization, and infant delivery at our institution. Aortic and pulmonary artery diameters were measured from real-time ultrasound or videotaped scans and compared against published nomograms. The pulmonary artery to aorta ratio was also evaluated in a similar manner. Infant survival was assessed 1 year after delivery.

Seventeen fetuses were confirmed to have a ventricular septal defect and an overriding aorta with varying degrees of right ventricular outflow obstruction after delivery. All karyotypes were normal. Ultrasound screening identified 12 of 17 abnormal hearts at a mean gestational age of 22.9 +/- 5.1 weeks; two of these fetuses were thought to have only ventricular septal defect before delivery. Five fetuses had enlarged aortic roots during the initial scan. Only two of the ten fetuses with a measurable pulmonary artery had initial sonographic evidence for valve stenosis. Six other pulmonary arteries became abnormally small with advancing pregnancy. The pulmonary artery to aorta ratio was decreased in six of the ten fetuses with a measurable pulmonary artery. Sixteen infants survived at least 1 year after birth and successfully completed either corrective or palliative cardiac surgery.

Fetuses with tetralogy of Fallot may present with only a ventricular septal defect and aortic septal override by prenatal ultrasound examination. Pulmonary artery stenosis is not always present at initial ultrasound examination, but this finding can develop or worsen during pregnancy. Furthermore, a normal aortic diameter does not exclude tetralogy of Fallot. Infant survival appears to be favorable in the absence of other major structural or chromosomal anomalies.