Two Cases of 2:1 Atrioventricular Block in Infants with Idiopathic Long QT Syndrome

ABSTRACT

Idiopathic long QT syndrome(LQTS) is an important cause of syncope, seizures, serious ventricular arrhythmias and sudden death in children. The abnormalities of AV conduction such as 2:1 AV block in children with LQTS is rarely reported. We reported two cases of 2:1 atrioventricualr block in infants with LQTS. Patient 1, a female newborn, revealed bradycardia(60 beats/min) and QTc of 0.65sec with 2:1 AV block at birth. She died of polymorphic ventricular tachycardia at 26days of age. Patient 2, a 2-month-old female, exhibited prolonged QT interval (QTc=0.54sec), 2:1 AV block, and intermittent Wenckebach conduction. After she received propranolol, sinus rhythm with 1:1 AV conduction and QTc of 0.5sec was seen. After a follow-up of 6 months, the infant is still doing well.