Hepatic venous wave protraction time is longer in late than in early pregnancy

Abstract

Background: Venous pulse waves, as obtained by Duplex Ultrasonography, are a reflection of cardiac right atrial function. The time-interval between cardiac electrocardiographic (ECG) signals and venous Doppler waves is the so-called Venous Wave Protraction Time (VWPT).

Aim: To evaluate Hepatic Vein (HV) VWPT at different stages of gestation.

Methods: Cross-sectional study in 4 groups of 10 women at gestations (1) 10-14 weeks, (2) 18-23 weeks, (3) 28-33 weeks and (4) ≥ 37 weeks. Three consecutive venous Doppler waves were recorded at the craniocaudal midportion of the liver from each of the three main branches of HV, simultaneously with an ECG. The time-interval between the ECG P-wave and corresponding A-deflection of venous Doppler waves was measured, without or with correction for gestation-induced changing heart rate (PA and PA/RR respectively). For each group, means and SD were calculated and compared statistically using conventional F-tests for linear mixed-effects models (SAS procedure MIXED).

Results: PA and PA/RR were significantly larger at term than in the first trimester [337±74 versus 220±47 msec, p=0.0008 and 0.48±0.15 versus 0.29±0.09, p=0.0009 respectively]. When groups at early-, mid- and late gestation were compared, VWPT increased gradually with gestational age.

Conclusion: VWPT is significantly longer in late than in early pregnancy. This observation probably relates to maternal cardiovascular adaptation mechanisms, i.e. venous tone. Our study illustrates that VWPT may be a new parameter to study venous hemodynamics during pregnancy.