Aortic Regurgitation

The aortic valve is a semilunar valve, which typically has three cusps—left, right, and noncoronary—that are attached to the aortic wall to form the sinuses of Valsalva. Aortic regurgitation (AR) is caused by a variety of disorders affecting the valve cusps, the aortic root, or both. Nonrheumatic causes currently account for the majority of the underlying causes of aortic insufficiency, including congenitally malformed aortic valves, infective endocarditis, and connective tissue diseases. Chronic severe AR results in a state of gradual left ventricular (LV) volume overload with resultant progressive and eccentric hypertrophy and an increase in LV dimensions to counter high wall stress. In acute severe AR, the left ventricle does not adapt and dilate; therefore, the acute ventricular volume overload results severe elevation of end-diastolic pressure, leading to pulmonary edema. Because the ventricular end-diastolic volume is normal, the total stroke volume is not increased, and the effective forward cardiac output drops, leading to a low-flow state.