Alterations in time intervals of ductus venosus and atrioventricular flow velocity waveforms in growth-restricted fetuses

Abstract

Objective: To investigate time intervals of the ductus venosus (DV) flow velocity waveform (FVW) and those of the cardiac cycle that correspond with each DV-FVW component in fetuses with intrauterine growth restriction (IUGR) due to placental insufficiency.

Methods: Women with a pregnancy complicated by IUGR were recruited into the study, as was a normal control group. Time intervals for systolic (S) and diastolic (D) components were measured in DV-FVW as follows: S(DV), from the nadir of the a-wave during atrial contraction to the nadir between the S-wave and D-wave; D(DV), from the nadir between S-wave and D-wave to the nadir of the a-wave. Regarding cardiac cycles, the following variables were measured from ventricular inflow through the tricuspid valve (TV) and mitral valve (MV): S(TV) and S(MV), from the second peak of ventricular inflow caused by atrial contraction (A-wave) to the opening of the atrioventricular valve; D(TV) and D(MV), from the opening of the atrioventricular valve to the peak of the A-wave. In the IUGR group, only the last examination performed within 1 week of delivery was used for analysis. All variables were analyzed statistically using Z-scores.

Results: Data were obtained from 249 normal fetuses and 26 fetuses with IUGR. Compared to normal fetuses, S(DV) showed a significant decrease (P < 0.001), while D(DV) showed a significant increase (P < 0.001) in the IUGR group. Regarding cardiac cycles, S(TV) and S(MV) showed significant decreases (P = 0.014 and P < 0.001, respectively) and D(TV) and D(MV) showed significant increases (P = 0.008 and P = 0.002, respectively) in fetuses with IUGR.

Conclusion: Time-interval alterations of DV-FVW in growth-restricted fetuses reflect the hemodynamic events caused by placental insufficiency.

Keywords: Doppler; cardiac cycle; ductus venosus; intrauterine growth restriction; time-related analysis.