Simultaneous Doppler recording of the pulmonary artery and vein: a new technique for the evaluation of a fetal arrhythmia.

We describe a new technique to evaluate cardiac rhythm using color and pulsed Doppler ultrasonography to identify and record pulmonary arterial and venous waveforms. Fifty fetuses were examined during the second and third trimesters of pregnancy. Simultaneous pulsed Doppler recording of the pulmonary artery and vein was obtained in 100% of fetuses between 15 and 40 weeks' gestation. Atrial systole was identified from the pulmonary vein and was manifested by an interruption of venous flow. Ventricular systole was manifested by a sharp peak that returned toward the baseline before it continued through the duration of systole as a lower-velocity waveform. This technique has the following advantages: (1) the lung parenchyma is easily accessible, irrespective of fetal position; (2) the pulmonary arteries and veins are adjacent to each other as they enter and exit the lung, thus making it easy to simultaneously obtain Doppler recordings of these vessels; (3) the pulsed Doppler waveform has an appearance similar to an electrocardiogram.