The idiopathic long Q-T syndrome.

Progress has been made in the diagnosis and management of the idiopathic long Q-T syndrome. The association of typical repolarization abnormalities and syncope during stress is characteristic of this syndrome. The pathogenetic mechanism has been largely, although not completely, elucidated. The data available support the hypothesis of a congenital imbalance between right and left-sided cardiac sympathetic innervation with left dominance; sudden sympathetic neural discharges trigger the malignant arrhythmias. Although mortality in untreated patients is extremely high, either beta-adrenergic blocking agents or a high thoracic left sympathectomy provide protection. Because many questions remain unanswered, a world-wide prospective registry has been initiated to provide the necessary information on the management of these patients. The registry constitutes a long-term (25 years) follow-up program and includes over 200 patients affected by the long Q-T syndrome.