Arrhythmias, Cardiac [Disease/Finding] Atrial Fibrillation [Disease/Finding] N0000000507 C0004238 M0001926 C1192 Atrial Fibrillation D001281 1023706 Abnormal cardiac rhythm that is characterized by rapid, uncoordinated firing of electrical impulses in the upper chambers of the heart (HEART ATRIA). In such case, blood cannot be effectively pumped into the lower chambers of the heart (HEART VENTRICLES). It is caused by abnormal impulse generation. Auricular Fibrillation 49436004 Atrial Fibrillation