Accuracy of right ventricular output estimated by Doppler echocardiography in the sheep fetus

Abstract

Our goal was to determine whether Doppler ultrasonographic estimation of fetal right ventricular output was accurate enough to evaluate fetal cardiac performance before the technique can be applied with confidence to the human fetus. The accuracy of this method has not been validated experimentally. We compared the right ventricular output measured by Doppler echocardiography with that determined from a transit-time ultrasonic flowmeter placed around the fetal pulmonary trunk and to that determined by microsphere technique. We obtained 72 Doppler flow measurements and 16 microsphere flow measurements in six fetuses. There was a fair correlation between cardiac output estimated by Doppler echocardiography performed transabdominally and that determined by a transit-time flowmeter (r = 0.76). The correlation was excellent when Doppler echocardiography was performed by the trans-uterine approach (r = 0.94). There was also an excellent correlation between right ventricular output determined by a transit-time flowmeter and that by microsphere technique (r = 0.94). Doppler echocardiographic estimation of fetal right ventricular cardiac output is thus feasible and accurate.