Aortic regurgitation (AR), also known as aortic insufficiency (AI), is the leaking of the aortic valve of the heart that causes blood to flow in the reverse direction during ventricular diastole, from the aorta into the left ventricle. As a consequence, the cardiac muscle is forced to work harder than normal. Signs and symptoms
Symptoms of aortic regurgitation are similar to those of heart failure and include the following:
Dyspnea on exertion
Orthopnea
Paroxysmal nocturnal dyspnea
Palpitations
Angina pectoris
Cyanosis (in acute cases)

Causes
In terms of the cause of aortic regurgitation, is often due to the aortic root dilation (annuloaortic ectasia), which is idiopathic in over 80% of cases, but otherwise may result from aging, syphilitic aortitis, osteogenesis imperfecta, aortic dissection, Behçets disease, reactive arthritis and systemic hypertension. Aortic root dilation is the most common cause of aortic regurgitation in developed countries. Additionally, aortic regurgitation has been linked to the use of some medications, specifically medications containing fenfluramine or dexfenfluramine isomers and dopamine agonists. Other potential causes that affect the valve directly include Marfan syndrome, Ehlers–Danlos syndrome, ankylosing spondylitis, and systemic lupus erythematosus. In acute cases of aortic regurgitation, the main causes are infective endocarditis, aortic dissection or trauma. Pathophysiology
The mechanism of aortic regurgitation, comprises the pressure in the left ventricle falling below the pressure in the aorta, the aortic valve is not able to completely close. This causes a leaking of blood from the aorta into the left ventricle. This means that some of the blood that was already ejected from the heart is regurgitating back into the heart.
ECG typically indicates left ventricular hypertrophy. Cardiac chamber catheterization assists in assessing the severity of regurgitation and any left ventricular dysfunction. Physical examination
The physical examination of an individual with aortic regurgitation involves auscultation of the heart to listen for the murmur of aortic regurgitation and the S3 heart sound (S3 gallop correlates with development of LV dysfunction). The murmur of chronic aortic regurgitation is typically described as early diastolic and decrescendo, which is best heard in the third left intercostal space and may radiate along the left sternal border. If there is increased stroke volume of the left ventricle due to volume overload, an ejection systolic flow murmur may also be present when auscultating the same aortic area. Unless there is concomitant aortic valve stenosis, the murmur should not start with an ejection click. There may also be an Austin Flint murmur, a soft mid-diastolic rumble heard at the apical area; it appears when a regurgitant jet of blood from severe aortic regurgitation partially closes the anterior mitral leaflet. Peripheral physical signs of aortic regurgitation are related to the high pulse pressure and the rapid decrease in blood pressure during diastole due to blood returning to the heart from the aorta through the incompetent aortic valve, although the usefulness of some of the eponymous signs has been questioned: Phonocardiograms detect AI by having electric voltage mimic the sounds the heart makes.Characteristics- indicative of aortic regurgitation are as follow:

Classification
The hemodynamic sequelae of AI are dependent on the rate of onset of AI.