DAVID MONTGOMERY: Aortic stenosis is a tightening of one of the four major valves of the heart. The aortic valve is particularly important because the aortic valve is the gateway to the rest of the body. So the heart pumps blood through the aortic valve to all the cells in the body. When aortic stenosis occurs, there is a tightening and oftentimes calcification of the aortic valve and that leads that valve to not be pliable but very rigid. And when the valve can't open, the blood that's chock full of goodies and oxygen and all the things that the cells need to function is not getting there because of a rigid, tight valve. The progression of aortic stenosis goes from mild, where we see just mild calcification in the valves not really that tight, to moderate. It's tightening a bit. It's thickening more. And then finally severe, where the valve is so rigid that it's not opening enough to feed the rest of the body all the blood that it needs to function. Mild stenosis is very often asymptomatic. That means the patient won't necessarily feel it in and of itself. When a patient develops severe aortic stenosis, this is most often when they develop symptoms. The first one is chest discomfort. Second is shortness of breath. The third is fainting or feeling faint. So the treatment for mild and moderate aortic stenosis really is aimed at preventing the progression of the disease. And so we aim to lower cholesterol. Keep the blood pressure down. If people smoke, we get them to stop smoking. Exercise and diet. For severe aortic stenosis, the treatment involves replacing the aortic valve. And so prompt treatment is very important. So if you develop chest pain, have shortness of breath or feel faint, you should seek medical attention right away.