Venous return to the fetal heart from the fetal brain

Аннотация

Objective. To compare venous return from fetal low body and venous return from fetal brain.

Полный текст

Methods. Blood flow waveforms in the inferior vena cava (IVC) and jugular vein (JV) were recorded in 30 normal fetuses at 13-16, 21-24 and 29-32 weeks of gestation (Aloka 2000). The IVC and JV flow velocity waveforms consisted of three components: the first represented forward flow during ventricular systole; the second component represented forward flow, which was coincident with early diastolic fillings; the third component depicted reverse flow reflecting atrial contraction. Time-velocity integral of forward flow (TVI FF) and time-velocity integral of reverse flow (TVI RF) were measured. Percent of reverse flow (%RF— TVI RF/ TVI FF) was calculated.

Results. In fetuses at 13-16 and 21-24 weeks of gestation reverse flow during atrial contraction expressed as %RF, was significantly greater in IVC (19,3±6,4%; 10,4±4,9%) than in JV (5,3±2,5%; 6,2±1,7%, p< 0,001). In fetuses at 29-32 weeks of gestation there was not different %RF in IVC and JV (6,2±1,7% and 5,2±2,9%, p> 0,10).

Conclusions. Our findings have suggested that fetal cardiac preload decrease with gestational age. %RF in IVC is greater than one in JV that may reflect special condition for venous return to fetal heart from fetal brain during normal pregnancy.