[Prolonged Q-T interval with functional A-V block in neonates and young infants (author's transl)].

A prolonged Q-T interval (0.56 to 0.70 s.) with second degree A-V block was present in 5 children. Auscultation in utero (2 cases) or at birth (1 case) and syncopal attacks at 15 days and 2 months of life led to the discovery of the arrhythmia which was complicated with torsades de pointes. One patient died at 1 month of age; another is treated with propranolol and an internal pacemaker; the last 3 recovered, either spontaneously or with propranolol. The originality of this syndrome of unknown etiology is due to the A-V block, secondary to delayed repolarization (prolonged Q-T interval). Torsades de pointes and ventricular fibrillation are the main risks. Treatment includes beta adrenergic blocking agents associated with a temporarily implanted pacemaker. In a few cases, the internal pacemaker has to be left permanently.