Perinatal manifestations of idiopathic long QT syndrome.

A neonate who had presented with sustained irregular heart rate during labor was found to have QT prolongation and repetitive polymorphic ventricular tachycardia (torsades de pointes) postnatally. Propranolol and propafenone successfully controlled the ventricular arrhythmias. Follow-up electrocardiograms and Holter records show persistent QT prolongation, bizarre T waves, and intermittent episodes of T wave alternans. On propranolol monotherapy the boy is thriving and completely free of ventricular arrhythmias. In the rare case of long QT syndrome in the neonate, early detection and therapy are mandatory to prevent ventricular arrhythmias and sudden death.