Aortic regurgitation (AR) is the diastolic flow of blood from the aorta into the left ventricle (LV). Regurgitation is due to incompetence of the aortic valve or any disturbance of the valvular apparatus (eg, leaflets, annulus of the aorta) resulting in the diastolic flow of blood into the left ventricular chamber. (See Pathophysiology and Etiology.)
Valvular abnormalities that may result in AR can be caused by the following (see Etiology, Presentation, and Workup):
Congenital causes - Bicuspid aortic valve is the most common congenital cause