FETAL DESCENDING AORTIC FLOW IN NORMAL AND IN-UTERO GROWTH-RESTRICTEDHUMAN FETUSES

Objective: To determine the hemodynamic and volume blood flow through the descending aorta, just below the ductus, in normally grown fetuses and in growth-retarded fetuses. Methods: One hundred twenty-four two- dimensional directed pulsed Doppler flow studies of the descending aor ta were evaluated in 52 normally grown fetuses and 72 growth-restricte d fetuses. The maximum diameter of the thoracic aorta was obtained dur ing systole using high resolution ultrasound. Descending aorta peak sy stolic velocity, time velocity integral, and acceleration time/ejectio n time were obtained using pulsed Doppler. Six consecutive cardiac cyc les were digitized and averaged. The systolic to diastolic ratio of th e umbilical artery as obtained at the level of the placental insertion . The descending aorta cross-sectional area was derived and multiplied by the time velocity integral to estimate the volume blood flow throu gh the descending aorta. Results: The diameter of the descending aorta was significantly smaller in a group of growth-restricted fetuses. Ti me velocity integral, peak systolic velocity, and acceleration time/ej ection time and volume blood flow of the descending aorta indexed to e stimated fetal weights were not different between the two groups even when the data were reanalyzed based on a systolic/diastolic ratio-grea ter than 3. Conclusions: The diameter of the descending aorta of growt h-restricted fetuses was smaller than the normally grown fetuses. The measured and derived descending aorta hemodynamic parameters were not significantly decreased in growth-restricted fetuses. Aortic flow may thus be quite variable in growth-restricted but not severely compromis ed fetuses.