Supplementary Material for: Valley index as a predictor of prenatal diagnosis of total anomalous pulmonary venous connection

Introduction: Total anomalous pulmonary venous connection (TAPVC) has a low prenatal diagnostic rate. Therefore, we investigated whether Doppler waveforms with a low pulsatility in the pulmonary veins can indicate fetal TAPVC.
Methods: This retrospective study included 16 fetuses with TAPVC, including 10 with complex congenital heart disease and 104 healthy fetuses that underwent fetal echocardiography. Pulmonary venous S and D wave flow velocities and the valley (representing the lowest velocity between the S and D waves) were measured. Valley indices I and II were then calculated as (velocity of valley/ greater of the S and D wave velocities) and (velocity of valley/lesser of the S and D wave velocities), respectively.
Results: Supra/infracardiac TAPVC cases exhibited significantly greater valley indices than that of the healthy group. After adjusting for gestational age at fetal echocardiography, valley index I (odds ratio [OR] 7.26, p < 0.01) and II (OR 9.23, p < 0.01) were significant predictors of supra/infracardiac TAPVC. Furthermore, valley indices I and II exhibited a high area under the curve for detecting supra/infracardiac TAPVC, regardless of the presence of pulmonary venous obstruction.
Conclusion: The valley index may be a useful tool for the detection of fetal TAPVC.