Prenatal diagnosis of congenital fetal arrhythmias by simultaneous pulsed Doppler velocimetry of the fetal abdominal aorta and inferior vena cava.

Various methods have been used for the diagnosis of congenital fetal arrhythmias. Currently, M-mode echocardiography is the most widely used method. However, good tracings are often difficult to obtain because of unfavorable fetal positions, resulting in long durations of examination. In early gestation, the fetal heart is often too small for clear M-mode echocardiography. Doppler velocity waveforms of the fetal inferior vena cava represent the right atrial activity, whereas those of the aorta reflect ventricular contraction. Because of the proximity of the vessels, it is easy to obtain simultaneous recording in opposite channels of Doppler waveforms from both vessels. A visual relationship between the atrial and ventricular contractions may be clearly established and a diagnosis may be made. The findings of simultaneous pulsed Doppler velocimetry of the fetal aorta and inferior vena cava were assessed in different types of congenital fetal arrhythmia: congenital heart block, premature atrial ectopic contractions, premature ventricular ectopic contractions, and supraventricular tachycardia. The correct diagnosis was made as early as 13 weeks' gestation, showing the application of this method in early pregnancy.