Measurement of Pulse Wave Velocity in Fetal Descending Aorta with Dual Doppler Method: a Preliminary Study

Pulse wave velocity (PWV) reflects blood pulse pressure. We attempted to determine whether commercially marketed ultrasound machine can accurately measure the PWV of the descending aorta of the human fetus. Thirty-two singleton pregnant women participated. Eight women (tocolysis group) were given ritodrine hydrochloride, and the other 24 women (normal group) were not. The descending aorta of the fetus was depicted in the longitudinal direction. Two distant sample volumes were set, and two Doppler waveforms were simultaneously obtained. The distance between the two sample volumes was divided by the time interval between the start of the two waveforms, and a PWV value was obtained. (1) Scatter diagrams for the gestational week and PWV were made, and a linear regression analysis was determined. (2) The PWV for the normal group was compared with the PWV for a group described in a previous report, one measured using ultrasonic phased-tracking. (3) The PWV values in the tocolysis group were compared with those in the normal group. (1) Significant correlations between PWV and gestational weeks were not found. (2) The mean (SE) of the PWV was 2.1 (0.12) m/s, which was similar to the PWV (2.2 (0.069) m/s) measured with ultrasonic phased-tracking. (3) The mean (SE) of the PWV (2.6 (0.25) m/s) in the tocolysis group was larger than that in the normal group (p = 0.032). The PWV of the descending fetal aorta could be accurately and conveniently measured with a commercially marketed ultrasound machine. In addition, PWV measurement with dual Doppler technique had ability to detect fetal cardio-vascular changes by ritodrine infusion.