[Hereditary long QT syndrome].

The Long QT Syndrome (LQTS) is a hereditary disease, characterized by a prolonged QT-interval on the electrocardiogram and a high risk of syncope and sudden death due to ventricular arrhythmias. LQTS must be suspected in apparently healthy children and young people with syncope after emotional or physical stress. Untreated symptomatic patients have a high mortality, which is markedly reduced by sympathetic block. The knowledge of the diagnostic criteria for the LQTS, a detailed history including a family history and an ECG-recording with measurement of the QT-interval in every patient with inexplicable syncope will advance the diagnosis of the LQTS and improve the survival of these patients after proper therapy. The current knowledge on the molecular genetics, epidemiology, mechanisms of arrhythmias and therapy are presented with special emphasis on the defects in the control of ionic transport over the cell membrane caused by mutations in ion channels.