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

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

METHODS: Time intervals for systolic (S) and diastolic (D) components were measured in DV-FVW as following: SDV , from the nadir of the a-wave during atrial contraction to the nadir between S-wave and D-wave; DDV , from the nadir between S-wave and D-wave to the nadir of a-wave. Regarding the cardiac cycles, the following variables were measured in ventricular inflow through tricuspid valve (TV) and mitral valve (MV): STV and SMV , from the second peak of ventricular inflow caused by atrial contraction (A-wave) to the opening of the atrio-ventricular valve; DTV and DMV , from the opening of the atrio-ventricular valve to the peak of A-wave. All variables were statistically analyzed using z-score.

RESULTS: The data were obtained from 249 normal fetuses and 26 IUGR fetuses. Compared to normal fetuses, SDV showed a significant decrease (P < 0.001), while DDV increased significantly (P < 0.001) in the IUGR group. Regarding the cardiac cycles, STV and SMV decreased significantly (P = 0.014 and P < 0.001, respectively), and DTV and DMV showed significant increases (P = 0.008 and P = 0.002, respectively) in IUGR fetuses.

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