An incomplete closing of the aortic valve, causing blood to flow backward into the left ventricle.

Improper closing of the aortic valve, allowing a back flow of blood.

Failure of the aortic valve to prevent backflow of oxygen-rich blood from aorta to left ventricle, resulting in dilatation, hypertrophy and ultimately failure of the pumping mechanism.

Aortic insufficiency (AI), also known as aortic regurgitation (AR), 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.