Long QT Syndrome, Brugada Syndrome, Right Ventricular Cardiomyopathy, Hypertrophic Cardiomyopathy, and Commotio Cordis

The hereditary long QT syndrome (LQTS) is a rare disorder characterized by prolongation of the QT interval on the electrocardiogram (ECG) and a propensity for syncope, torsades de pointes, ventricular arrhythmias, and sudden death. One form of LQTS, described by Jervell and Lange-Neilsen in 1957, is characterized by deafness and autosomal recessive inheritance (1). The most common form of LQTS was initially described by Romano (2) and Ward (3), and is characterized by autosomal dominant inheritance and normal hearing. Remarkable progress has been made in the last several years in our understanding of the pathogenesis of LQTS. It is now clear that LQTS is a heterogeneous disorder caused by mutations in specific ion channels that play a critical role in the control of cardiac repolarization (4). These findings have revolutionized our understanding of LQTS, and may yield new insights into other conditions characterized by ventricular arrhythmias in the absence of ischemia or structural heart disease. Recent work has also identified LQTS as an important cause of sudden infant death syndrome (SIDS) (5,6).