A variant of long QT syndrome manifested as fetal tachycardia and associated with ventricular septal defect.

Two patients with a novel variant of long QT syndrome are described. The clinical course was characterised by an in utero onset of ventricular tachycardia and atrioventricular block (at 26 and 30 weeks' gestational age, respectively), and an association with a ventricular septal defect. Studies of both patients' families identified relatives with prolonged QT interval, syncope, or sudden death. One patient died of intractable ventricular tachycardia at 4 days old. The other received beta blocker treatment and a pacemaker. She died suddenly at the age of 10 months. The unique association with ventricular septal defect and the malignant clinical course warrants further molecular diagnosis of this novel variant of long QT syndrome.