Fetal echocardiographic measurements and the need for neonatal surgical intervention in Tetralogy of Fallot.

Background: This study aimed to evaluate fetal echocardiographic measurements at the time of the first fetal echocardiogram as predictors of neonatal outcome for tetralogy of Fallot (TOF).

Methods: The study reviewed all infants with a prenatal diagnosis of TOF from January 2004 to June 2011. Aortic valve (AoV), pulmonary valve (PV), main pulmonary artery (MPA), left and right pulmonary artery diameters, and ductus arteriosus flow were evaluated on fetal echocardiograms, and associations between the fetal echocardiogram and the neonatal echocardiogram measurements and outcomes were assessed.

Results: The study identified 67 TOF patients who had an initial fetal echocardiogram at a mean gestational age of 25.0 ± 5.2 weeks. Patients with absent PV syndrome or major aortopulmonary collaterals were excluded from the study, as were those without anterograde pulmonary blood flow at the first fetal echocardiogram. Of the remaining 44 patients, 10 were ductal dependent and required neonatal surgery. Infants who were ductal dependent had lower fetal PV (-5.38 ± 2.95 vs. -3.51 ± 1.66; p < 0.05) and MPA (-3.94 ± 1.66 vs. -2.87 ± 1.04; p < 0.05) z-scores. A fetal PV z-score of -5 predicted ductal dependence with 78 % sensitivity and 87 % specificity, and a PV z-score of -3 showed 100 % sensitivity and 34 % specificity (p < 0.001). Fetuses with a reversed left-to-right flow across the ductus arteriosus (DA) were more likely to be ductal dependent (odds ratio, 25; p < 0.001) than those who had normal ductal flow.

Conclusions: In TOF, fetal PV and MPA z-scores and direction of the DA blood flow predict neonatal ductal dependence. Patients with fetal PV z-scores lower than -3 or any left-to-right flow at the level of the DA should be admitted to a center where prostaglandin is available.