[Fetal hemodynamics evaluated by pulsed Doppler echocardiography].

The hemodynamics of fetal hearts, possibly having right ventricular overload were investigated using pulsed Doppler and cross-sectional echocardiography. The subjects consisted of 250 normal fetuses at 30 to 38 weeks gestation, 23 of which were studied by Doppler method. The ultrasonic beam was directed toward the centers of the tricuspid and mitral orifices imaged in the apical four-chamber view to record right ventricular and left ventricular inflow velocities. The flow velocity patterns of right and left ventricular inflow tracts were similar and consisted of two peaks; the rapid filling phase and the atrial contraction phase. The peak velocity of the atrial contraction phase was slightly greater than that of the rapid filling phase. Mitral peak flow velocity was 52.1 +/- 9.9 cm/sec (mean +/- SD), while tricuspid peak flow velocity was 56.1 +/- 8.7 cm/sec, and the ratio of the latter to the former was 1.09 +/- 0.09. We calculated the excursions and diastolic descent rate (DDR) of the mitral and tricuspid valves using M-mode echocardiography, which were also strongly affected by stroke volume. TV DDR/MV DDR = 1.06 +/- 0.10, and TV excursion/MV excursion = 1.09 +/- 0.09. Reportedly, 2/3 of the total cardiac volume entered the right ventricle, based on the experimental study of fetal lambs. However, the results obtained in the present study suggest that the right ventricular flow volume may be only slightly greater than that of the left ventricle.