valve stenosis means the aortic valve has narrowed and is not opening freely. The aortic valve opens to allow blood to flow from the left ventricle to the aorta. Stenosis here leads to a narrowing of the passage for blood to flow out of the left ventricle, thus a LVOTO. More than 50% of patients with aortic valve stenosis have a congenital heart abnormality called a bicuspid aortic valve. The aortic valve is normally three leaflets but when it is bicuspid it is made of two. This increases the risk for aortic stenosis due to increased stress on the leaflets, calcium deposition, turbulent blood flow, and scarring. If the stenosis is severe enough, surgical intervention may be necessary. References Congenital heart defects