II. Ductus venosus and inferior vena cava blood flows during normal pregnancy

Abstract

Experimental studies have shown that inferior vena cava blood passes through the right atrium mainly to the right ventricle. Ductus venosus blood, which contains well-oxygenated umbilical blood, passes through the foramen ovale to the left atrium and left ventricle. Thus, S and D wave of DV waveforms could reflect the hemodynamic status of the left ventricle whereas S and D wave IVC waveforms could reflect the hemodynamic status of the right ventricle.

Full Text

Objective. To compare dynamic of S/D ratio in ductus venosus (DV) with one in inferior vena cava (IVC) during normal pregnancy.

Methods. Blood flow waveforms in the DV and IVC were recorded in 162 fetuses from normal pregnancies between 9 and 40 weeks of gestation (Aloka 2000). Peak systolic (S) diastolic (D) velocities of blood flow waveforms and S/D ratio were measured.

Results. DV S/D ratio decreased as a function of increasing gestational age [SD = 1,721 — 0,231 x (weeк’s gestation) + 0,07 x (week’s gestation), p<0,0001]. This was attributed to an increase in the velocity of D wave. IVC S/D ratio increased with advancing gestational age [SD = 1,628 + 0,0018 x (week’s gestation)²; p<0,002] because of the increasing in the velocity of S wave.

Conclusions. Our findings have suggested that compliance of the right ventricle could be different from left one.