Atrial fibrillation
Atrial fibrillation is a type of arrhythmia characterized by rapid and irregular heart rhythms due to irregular atrial activation by the atrioventricular (AV) node. In the pathogenesis of atrial fibrillation, there is no effective pumping of blood into either the pulmonary or systemic circulation from the left ventricle of the heart. The left and right ventricles (lower chambers of the heart) do not fill properly due to the irregular contraction of the left and right atria (upper chambers of the heart).