Correlation between ductus venosus spectrum and right ventricular diastolic function in isolated single-umbilical-artery foetus and normal foetus in third trimester

BACKGROUND: Single umbilical artery (SUA) is the most common umbilical cord malformation in prenatal diagnosis. The presence of an SUA can cause blood circulation disorder in the foetus and functional changes of the foetal heart, affecting foetal circulation. The right ventricular diastolic functions in foetuses with isolated SUA and in normal foetuses in the third trimester were evaluated using the spectral Doppler of blood flow in the foetal ductus venosus (DV). AIM: To evaluate the right ventricular diastolic functions in foetuses with isolated SUA and in normal foetuses in the third trimester. METHODS: Colour Doppler was used to measure the spectrum of foetal DV and tricuspid orifice in 34 foetuses with isolated SUA aged 28-39 wk and in age-matched healthy controls. The DV flow velocities and velocity ratios were measured. The early passive/late active (E/A) ratio at the tricuspid orifice and tissue Doppler Tei index of the foetal right ventricular in the two groups were also measured. RESULTS: During the third trimester, the isolated SUA group showed a lower ‘a’-wave peak velocity in the DV than the control group (P < 0.05). The correlations between the velocity ratios and E/A ratio at the tricuspid orifice in the two groups were analysed, and the correlation between the ventricular late diastolic velocity/ventricular diastolic peak flow velocity and E/A ratios was the best (R(2 )of the isolated SUA group: 0.520; R(2 )of the control group: 0.358). The correlations between the velocity ratios and tissue Doppler Tei index of foetal right ventricular in the two groups were analysed, and the correlation between the pulsatility index for veins (PIV) and tissue Doppler Tei index ratios was the best (R(2) of the isolated SUA group: 0.865; R(2) of the control group: 0.627). CONCLUSION: In the isolated SUA group, the atrial systolic peak velocity ‘a’ decreased, and this finding might be related to the changes in foetal cardiac functions. The ratio of ventricular late diastolic velocity to ventricular diastolic peak flow velocity was closely related to the E/A ratio at the tricuspid valve and can be used to identify changes in the right ventricular diastolic functions of isolated SUA and healthy foetuses. PIV was closely related to the tissue Doppler Tei index of the foetal right ventricular and can be used to identify the right ventricular overall functions of isolated SUA and healthy foetuses.