TY - CHAP M1 - Book, Section TI - Atrial Fibrillation A1 - Kapur, Sunil A1 - MacRae, Calum A. A2 - Murray, Michael F. A2 - Babyatsky, Mark W. A2 - Giovanni, Monica A. A2 - Alkuraya, Fowzan S. A2 - Stewart, Douglas R. Y1 - 2014 N1 - T2 - Clinical Genomics: Practical Applications in Adult Patient Care AB - Disease summary:Atrial fibrillation (AF) is the most common clinical arrhythmia (affecting ~10% of those in the seventh decade of life) and is a major cause of morbidity and mortality. AF is traditionally regarded as a sporadic, nongenetic disorder, but the ability to sustain the arrhythmia has long been known to require some underlying diathesis. There is growing evidence of an important heritable basis for many forms of AF, with the recent identification of several genetic determinants.In AF the normal electrical impulses that are generated by sinoatrial node are replaced by waves of disorganized electrical activity that result from a combination of very rapidly firing triggers and abnormal conduction within local atrial re-entry circuits. This prevents co-ordinated contraction of the muscle which instead fibrillates in an uncontrolled manner (this leads to the arrhythmia’s name). As a result the impulses reaching the ventricle to generate the hemodynamically important contracile activity are also highly irregular.The arrhythmia involves the two upper chambers (right and left atria) of the heart, though in some instances the origins of the rapid electrical triggers may be in bands of cardiac muscle that envelop the ends of the pulmonary veins as they insert into the posterior aspect of the left atrium.Clinical presentation: AF most often arises in the setting of other forms of heart disease, though there is evidence of shared mechanisms across these different contexts. AF may also arise in the absence of evidence of any associated cardiac disorder, so called lone AF. AF is often asymptomatic, but it may result in palpitations, dyspnea, chest tightness or pain, and even congestive heart failure (HF) in those predisposed. Individuals with AF have an increased risk of stroke both embolic and hemorrhagic. There may be typical precipitants for AF episodes including exercise or sleep. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/28 UR - accessmedicine.mhmedical.com/content.aspx?aid=1102699291 ER -