The long QT syndrome has become the focus of considerable scientific attention in recent years because of the discovery of several genes responsible for its development. These discoveries have demonstrated the genetic heterogeneity of the syndrome and have given both the clinician and researcher the opportunity to relate phenotypic variants to different genotypes responsible for distinctly different ion channel abnormalities. These analyses - which are comprehensively reviewed and explored here for the first time - are now beginning to suggest treatment strategies specific to each genotype.The full power of such precise diagnosis promises highly targeted and very successful therapy. In the author's own words, there is 'the progressive realization that behind the surface of an infrequent disease may lie the key to understanding the mechanisms by which modulation of autonomic function may enhance or prevent the occurrence of life-threatening arrhythmias'.The aim of the Clinical Approaches to Tachyarryhthmias series is to update the physician, cardiologist, and all those responsible for the care of patients with cardiac arrhythmias. In this volume, one of the foremost research pioneers in the field provides a clear and comprehensively considered account of this syndrome's history, significance, and exciting current status. Readers will gain a better understanding of why the long QT syndrome has been the focus for numerous theories of arrhythmogenesis, why it has been the test bed for many antiarrhythmic treatments, and why it remains the paradigm for the diagnosis and management of cardiac arrhythmias.