Left Cardiac Sympathetic Denervation in Long QT Syndrome Patients

The idiopathic long QT syndrome (LQTS) is an unusual clinical disorder characterized by a prolongation of the QT interval and by syncopal episodes occurring among young subjects, most often during exercise, stress, or other conditions of increased sympathetic activity. Both an imbalance in sympathetic innervation and an intracar-diac defect in membrane currents have been proposed as pathogenetic. mechanisms. The latter appears substantiated by recent advances in molecular genetics showing a linkage on chromosomes 11,3,7, and 4, with identification of the genes for chromosomes 3 and 7. For symptomatic patients with the long QT syndrome, β-adrenergic blockade, with efficacy in approximately 80% of patients, currently remains the therapy of first choice. For the patients who continue to suffer syncope or cardiac arrest despite β blockade, evidence has been provided that left cardiac sympathetic denervation represents a very effective treatment. The improvement in the understanding of the molecular mechanisms involved may soon lead to gene specific therapy in most long QT patients.