This document discusses aortic regurgitation (AR), which occurs when the aortic valve does not close properly, allowing blood to flow backward into the left ventricle. It can be caused by damage to the aortic valve leaflets or distortion of the aorta. Common causes include rheumatic heart disease, bicuspid aortic valves, hypertension, and Marfan syndrome. Over time, the left ventricle must work harder to compensate for the backflow of blood, which can lead to enlarged and weakened heart muscles. Symptoms may include palpitations, chest pain, and shortness of breath. Diagnosis involves listening for an early diastolic murmur and confirming the diagnosis with echocardiogram