M-mode ultrasonic assessment of fetal cardiovascular dynamics.

A combined two-dimensional real-time and M-mode technique for measuring fetal right and left ventricular cardiac geometry and function is presented. From 64 normal women studied between 27 and 41 weeks gestation, 53 technically acceptable recordings showed a significant increase in left and right ventricular size. Both ventricles are geometrically and functionally uniform. Mean velocity of blood flow in the fetal descending aorta as measured by pulsed Doppler ultrasound showed no relation to mean velocity of fractional shortening of both cardiac ventricles.