Inside of the heart there is an aortic valve. This is a one-way valve with 3 leaflets (skin Flaps). The leaflets flip open up , which lets the blood flow out of the heart while it is still pumping. When the heart relaxes, between beats, the leaflets close up to keep blood from back-flowing. As you get older, calcium ha a tendency to build up on the leaflets causing them to not operate properly. This Narrowing of the Aortic Valve leads to blood, back wash.