Comparison of Reference Values and Z Scores of Pulse-Doppler Waveforms of Fetal Pulmonary Artery and Aorta

Doppler - derived fetal pulmonary artery acceleration time (PAAT) and acceleration - to - ejection time ratio (AT/ET) are important as predictors of a variety neonatal pulmonary diseases. The evaluation of PAAT and PA AT/ET are meaningful when simultaneous right and left heart studies are done. The unique cardiovascular physiology in the fetus, as the only period of life with physiologic systemic pulmonary hypertension, overemphasizes the significance of simultaneous study. However, studies on comparative fetal velocitometry of PA and aorta are scarce.
The aims of this study were to provide reference values for peak systolic velocity (PSV), pulsatility index (PI), acceleration time (AT), ejection time (ET) and AT/ET ratio of PA and aorta in the singleton pregnancies with healthy fetuses. We compared these Doppler parameters of PA and aorta.
A cross - sectional study was performed on 146 fetuses. We measured PSV, PI, AT, ET and AT/ET in the PA and aorta and compared the values. We evaluated the correlation between these parameters and the fetal gestational age (GA).
Mean ± SD of gestational age of fetuses were 21 ± 4 weeks. PSV, AT and AT/ET of PA and aorta increased with gestational age. PSV, PI, AT and AT/ET were significantly lower in the PA relative to the aorta.
Despite equal pressures in PA and aorta in the fetal period, the PSV, PI, AT and AT/ET are lower in the PA. This study indicates that, in contrast to children and adults, PA pressure is not the major determinant of fetal PAAT.