Recognition of fetal arrhythmias by echocardiography.

Fetal arrhythmias were detected in 33/198 high risk pregnancies from 21 weeks to term. Using the two-dimensional echocardiographic image of the fetal heart as a guide, the M-mode beam was directed to define the motion of the ventricular and atrial walls and atrioventricular valve or semilunar valves. Atrial contraction was defined either by the atrial wall motion or from the A-point of the atrioventricular valve. Ventricular contraction was defined by closure of the atrioventricular valve (C-point), the onset of ventricular wall contraction, or from the semilunar valve opening. Ladder diagrams of the sequence of atrial and ventricular activation were constructed to define the temporal sequence of these events. Premature atrial contractions were present in 12. In one fetus this arrhythmia converted into supraventricular tachycardia while in the other 11 fetuses the course was benign. Two fetuses had premature ventricular contractions. Supraventricular tachycardia was noted in five fetuses. One with hydrops at 29 weeks returned to sinus rhythm following maternal administration of procainamide. A second hydropic fetus with paroxysmal atrial tachycardia and hydrops failed to respond to digitalis, propranolol, procainamide, verapamil, or amiodarone, and died shortly after cesarean section. Two mature fetuses had tachycardia close to term and were treated after cesarean section. One fetus with runs of atrial tachycardia died in utero. Three fetuses had complete heart block, two of whom were from mothers with connective tissue diseases. In four fetuses, there was bradycardia of less than 100/minute lasting more than 30 seconds, but these episodes disappeared in 2 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)