Aortic valve stenosis is narrowing of the aortic valve. Many things can narrow this passageway between your heart and aorta. Causes of aortic valve stenosis include:

  • Congenital heart defect. The aortic valve consists of three tightly fitting, triangular-shaped flaps of tissue called leaflets. Some children are born with an aortic valve that has only one (unicuspid) or two (bicuspid) leaflets — not three. This deformity may not cause any problems until adulthood, at which time the valve may begin to narrow or leak and may need to be repaired or replaced. Having a unicuspid or bicuspid aortic valve requires regular evaluation by a doctor to watch for signs of valve problems. In most cases, doctors don't know why a heart valve fails to develop properly, so it isn't something you could have prevented.
  • Calcium buildup on the valve. With age, heart valves may accumulate deposits of calcium (aortic valve calcification). Calcium is a mineral found in your blood. As blood repeatedly flows over the aortic valve, deposits of calcium can accumulate on the valve's leaflets. These deposits may never cause any problems. However, in some people — particularly those with a bicuspid aortic valve — calcium deposits result in stiffening of the leaflets of the valve. This stiffening narrows the aortic valve. This cause of aortic valve stenosis is most common in people older than 65, and symptoms often don't appear until age 70.
  • Rheumatic fever. A complication of strep throat infection, rheumatic fever may result in scar tissue forming on the aortic valve. Scar tissue alone can narrow the aortic valve and lead to aortic valve stenosis. Scar tissue can also create a rough surface on which calcium deposits can collect, contributing to aortic valve stenosis later in life. Rheumatic fever may damage more than one heart valve, and in more than one way. A damaged heart valve may not open fully or close fully — or both. While rheumatic fever is rare in the United States, some older adults had rheumatic fever as children.

How your heart works

Your heart, the center of your circulatory system, consists of four chambers. The two upper chambers, the atria, receive blood. The two lower chambers, the ventricles, pump blood.

Blood returning to your heart enters the right upper chamber (right atrium). From there, blood empties into the right ventricle underneath. The right ventricle pumps blood into your lungs, where blood is oxygenated. Blood from your lungs then returns to your heart, but this time to the left side — to the left upper chamber (left atrium). Blood then flows into the left ventricle — your heart's main pump. With each heartbeat, the left ventricle forces blood through the aortic valve into the aorta, your body's largest artery.

Blood flows through your heart's chambers, aided by four heart valves. These valves open and close to let blood flow in only one direction through your heart:

  • Tricuspid valve
  • Pulmonary valve
  • Mitral valve
  • Aortic valve

The aortic valve — your heart's gateway to the aorta — consists of three tightly fitting, triangular-shaped flaps of tissue called leaflets. These leaflets connect to the aorta via a ring called the annulus.

Heart valves open like a one-way gate. The leaflets of the aortic valve are forced open as the left ventricle contracts and blood flows into the aorta. When all of the left ventricular blood has gone through the valve and the left ventricle has relaxed, the leaflets swing closed to prevent the blood that has just passed into the aorta from flowing back into the left ventricle.

A defective heart valve is one that fails to either open or close fully. When a valve doesn't close tightly, blood can leak backward. This backward flow through a valve is called regurgitation. When a valve narrows, the condition is called stenosis.

Jul. 13, 2012