Aortic valve stenosis (AS) is a heart disease caused by the incomplete opening of the aortic valve in the heart. Under some circumstances, the aortic valve becomes narrower than normal, impeding the flow of blood. This is known as aortic valve stenosis, or aortic stenosis. While discussing traditional therapies for this condition, this talk will focus on valve replacement through a new, less invasive method. From the Series:The Stanford University Medical Center Health Hour