The interpretation and medical management of complex arrhythmias in the newborn infant.

The clinical history, long term follow-up, and the surface electrocardiographic interpretation of four newborn infants with different arrhythmias are described. The arrhythmias discussed are: supraventricular tachycardia involving an accessory atrioventricular nodal bypass tract (Kent fibers), ectopic atrial tachycardia, atrioventricular nodal reentrant tachycardia, and ventricular tachycardia associated with congenital prolonged QT syndrome. Echocardiographic examination completed the evaluation in these newborns. A cardiac tumor was found in one infant and an aneurysm of the atrial septum was observed in two. Pharmacological therapy was successful in each newborn infant.