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

Figure 2 The ductus venosus flow velocities, velocity ratios and the early passive /late active ratio at the tricuspid orifice were measured. A: Typical flow velocity waveform of the ductus venosus. The peak velocities during ventricular systolic peak flow velocity (S), ventricular late diastolic velocity (v), ventricular diastolic peak flow velocity (D) and atrial systolic peak velocity (a) were measured to calculate the velocity ratios; B: From these waveforms, peak systolic velocities during early passive (E) and late active (A) ventricular filling were measured to calculate the E/A ratio for the tricuspid valve; C: Ductus venosus velocimetry of isolated single umbilical artery foetuses with small-for-gestational-age. The ductus venosus spectrum ‘a’-waves were backward.