Congenital aortic stenosis refers to a narrowed aortic valve with varying degrees of obstruction. Usually the valve is bicuspid, but other variations exist. Aortic stenosis is a spectrum in which the degree of obstruction ranges from mild to severe. Patients with mild aortic stenosis have no symptoms and do not require an intervention. Greater degrees of aortic stenosis can result in symptoms such as shortness of breath on exertion, chest pain, dizziness, or fainting. The most severe cases present in the newborn period, where there is critical obstruction and inadequate cardiac output which requires emergency intervention. Patients with symptoms from aortic stenosis, and most patients with asymptomatic severe obstruction, require treatment to relieve valve obstruction.