​A normal aortic valve has three leaflets, while a bicuspid aortic valve only has two. The aortic valve allows oxygen-rich blood to flow from the heart to the aorta, the main blood vessel that brings blood to the body. Bicuspid aortic valve is present at birth (congenital) and it is one of the most common congenital heart defects. This defect may occur in 1-2% of the population, predominantly in males. The bicuspid valve may be entirely undetected during childhood or even during adolescence. The bicuspid aortic valve defects are sometimes associated with other defects of the aorta and other left side heart abnormalities.