Long QT Syndrome
Section snippets
Ion-Channel Genes and Currents
QT prolongation is the hallmark of LQTS and may arise from either a reduction in the outward potassium current during phase 3 of the action potential (referred to as a “loss of function”) or an augmented late entry of sodium or calcium ions into the myocytes due to malfunctioning sodium or calcium channels (referred to as a “gain of function”).18 The most common genetic causes of LQTS involve mutations in genes regulating the α-subunits of the following: (1) the slowly activating potassium
Clinical Approach
Suspected LQTS patients are usually referred to a cardiologist or an electrophysiologist early after recently experiencing a cardiac arrhythmia, syncope, an aborted cardiac arrest, episode of palpitation, or sudden death/cardiac arrest in a relative.28 Since the majority of such individuals come to the physician's attention during adolescence or early adulthood, the differential diagnosis includes a spectrum of arrhythmogenic disorders including hypertrophic cardiomyopathy (HCM), arrhythmogenic
Summary
The identification of the molecular and clinical determinants of inherited LQTS has been pivotal to the understanding of important aspects of cardiac arrhythmias and sudden death. Data from molecular LQTS studies have provided novel insight into the fundamental nature of the electrical activity of the human heart and to the relationship between disturbances in ion flow and cardiac disease. Furthermore, recent studies from the International LQTS Registry that evaluated age-specific risk factors
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The authors have no conflicts of interest to disclose.