The aortic valve allows the passage of oxygenated blood from the left ventricle to the aorta, which is the main artery that distributes blood to the body. Normally, this valve has three gates, also known as cusps or valves. Occasionally, people are born with an aortic valve with only two cusps. This is called a bicuspid or bivalve aortic valve. A bicuspid aortic valve can be found in isolation, in an otherwise healthy heart; but it can also be associated with other heart defects.

Isolated bicuspid aortic valve is the most common congenital heart malformation, and usually has no effect on heart function. If the bicuspid aortic valve does not open properly, then we will have an aortic stenosis. The aortic valve is usually bicuspid in cases of aortic stenosis, a disease responsible for 3-6% of all cases of congenital heart disease.