Stenosis, Aortic Valve
Aortic valve stenosis — or aortic stenosis — is a condition in which the heart's aortic valve narrows. This narrowing prevents the valve from opening fully, which obstructs blood flow from your heart into your aorta and onward to the rest of your body. Aortic valve stenosis usually results in an abnormal heart sound (heart murmur) that doctors can hear with a stethoscope.
When the aortic valve is obstructed, your heart needs to work harder to pump blood to your body. Eventually your heart muscle becomes thicker because it has to pump harder due to the obstruction. In addition, your heart can pump only a limited amount of blood — and can't provide the increase in blood flow you need for activities such as exercise.
Several factors, including aging, can damage the aortic valve and lead to aortic valve stenosis. Some babies are even born with a defective aortic valve.
If you have severe aortic valve stenosis, you'll usually need surgery to replace the valve. Left unchecked, aortic valve stenosis can lead to serious heart problems.
Aortic valve stenosis obstructs the way blood normally flows through your heart and its valves. A number of factors can cause this disorder.
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 underneath — 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 tissues called leaflets. These leaflets connect to the aorta through 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 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 either to 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.
Aortic valve stenosis is narrowing of the aortic valve. Many factors can narrow this passageway between your heart and aorta. Causes of aortic valve stenosis include :
- Congenital heart defect. Rarely, some babies are born with an already narrowed aortic valve. Others are born with an aortic valve that has only two flaps (leaflets) — not three. Known as a bicuspid aortic valve, 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 bicuspid aortic valve requires regular evaluation by a doctor to watch for signs of valve malfunction. If you're the parent of a newborn, infant or child with aortic valve stenosis, you may have many questions and concerns. In most cases, doctors don't know why a heart valve fails to develop properly, but 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 60, and symptoms often don't appear until age 70 or 80.
- Rheumatic fever. Rheumatic fever — a complication of strep throat and a once-common childhood illness in the United States — can damage heart valves. 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 no longer prevalent in the United States, some older adults had rheumatic fever as children.
Aortic valve stenosis — of any cause — can be a serious condition because it can weaken the heart. If the aortic valve is narrowed, the left ventricle has to work harder to pump a sufficient amount of blood into the aorta and onward to the rest of your body. In response, the left ventricle may thicken and enlarge. At first these adaptations help the left ventricle pump blood with more force. But eventually these changes weaken the left ventricle — and your heart overall.
Risk Factor :
Aortic valve stenosis is often not preventable. Some people are born with an already narrowed aortic valve or develop aortic valve stenosis later in life because they were born with a bicuspid aortic valve — one with two flaps (leaflets) instead of three. A bicuspid aortic valve is a major risk factor for aortic valve stenosis.
Aortic valve stenosis also may be related to age and the buildup of calcium deposits on heart valves or a history of rheumatic fever.
When to seek medical advice :
Aortic valve stenosis most commonly affects adults, but can occur in children. Infants and children with the condition may experience symptoms similar to those of adults. If you or your child experiences such signs or symptoms, see a doctor — especially if you or your child has a known heart problem.
Aortic valve stenosis ranges from mild to severe. Signs and symptoms typically develop when narrowing of the valve is severe and can include :
- Chest pain (angina) or tightness
- Feeling faint or fainting with exertion
- Fatigue, especially during times of increased activity
- Shortness of breath, especially with exertion
- Heart palpitations — sensations of a rapid, fluttering heartbeat
- Heart murmur
When your aortic valve narrows, your heart can't pump blood as efficiently. Because your heart has to work harder to pump blood through a narrowed valve, over time the heart muscle may weaken, leading to congestive heart failure. Signs and symptoms of congestive heart failure include fatigue, shortness of breath, and swollen ankles and feet.
Aortic valve stenosis may not produce warning signs right away, making it difficult to detect at first. Aortic valve stenosis is often discovered during a routine physical when a doctor hears a heart murmur. This murmur may occur long before other signs and symptoms develop.
Depending on the amount of narrowing, an infant or child with aortic valve stenosis may have no symptoms, may tire easily or may have chest pain with vigorous physical activity.
As part of a routine physical, your doctor uses a stethoscope to listen to your heart. He or she is listening for, among other things, an abnormal heart sound (heart murmur).
If your doctor discovers a heart murmur, he or she will discuss it with you. Many heart conditions, including aortic valve stenosis, can produce a heart murmur. In the case of aortic valve stenosis, the heart murmur results from turbulent blood flow through the narrowed valve.
If your doctor suspects that you or your child may have a deformed or narrowed aortic valve, you may need to undergo several tests to confirm the diagnosis and gauge the severity of the problem. You may be referred to a cardiologist — a doctor who specializes in the study of the heart and its function — for tests such as :
- Electrocardiogram (ECG). In this test, patches with wires (electrodes) are attached to your skin to measure the electrical impulses given off by your heart. Impulses are recorded as waves displayed on a monitor or printed on paper. An ECG can provide clues about whether the left ventricle is thickened or enlarged, a problem which can occur with aortic valve stenosis.
- Chest X-ray. An X-ray image of your chest allows your doctor to check the size and shape of your heart, to determine whether the left ventricle is enlarged — a possible indicator of aortic valve stenosis. A chest X-ray can also reveal calcium deposits on the aortic valve. In addition, a chest X-ray helps your doctor check the condition of your lungs. Aortic valve stenosis may lead to blood and fluid backing up in your lungs, which causes congestion that may be visible on an X-ray.
- Echocardiogram. This test uses sound waves to produce an image of your heart. In an echocardiogram, sound waves are directed at your heart from a wand-like device (transducer) held on your chest. The sound waves bounce off your heart and are reflected back through your chest wall and processed electronically to provide video images of your heart. An echocardiogram helps your doctor closely examine the aortic valve to check for abnormalities. A specific type of echocardiogram, a Doppler echocardiogram, may be used to help your doctor determine the severity of your aortic valve stenosis and to check for any leakage (regurgitation).
- Cardiac catheterization. In this procedure, your doctor threads a thin tube (catheter) through an artery in your arm or groin to an artery in your heart. A dye injected through the catheter fills your heart's arteries, and the arteries become visible on an X-ray. This test helps show blockages in arteries to your heart that can coexist with aortic valve stenosis and may need surgical treatment along with aortic valve stenosis. Some catheters used in cardiac catheterization have miniature devices (sensors) at the tips that can measure pressure within heart chambers, such as your left ventricle. These sensors also provide doctors with important information about the rate of blood flow through the aortic valve to assess the severity of stenosis.
These tests and others help your doctor determine how narrow or tight your aortic valve may be and how well your heart is pumping. Once aortic valve stenosis is discovered, your doctor will either recommend treatment or suggest careful monitoring.
Aortic valve stenosis puts you at risk of endocarditis. Endocarditis is an infection of your heart's inner lining — the endocardium. This membrane lines the four chambers and four valves of your heart. Typically, the infection involves one of the heart valves, especially if it's already damaged. If the aortic valve is narrowed, it's more prone to infection than a healthy valve is.
You can develop endocarditis when bacteria from another part of your body spread through your bloodstream and lodge in your heart. If you have aortic valve stenosis, it's recommended that you take antibiotics before certain dental or medical procedures that may increase the likelihood of bacteria entering your bloodstream and causing an infection in your heart.
Left unchecked, aortic valve stenosis can lead to congestive heart failure. Congestive heart failure is a serious condition in which your heart is unable to pump sufficient blood to meet your body's needs. Severe aortic valve stenosis ultimately can be life-threatening. The condition can lead to irregular heart rhythms (arrhythmias) and cardiac arrest.
Medications sometimes can ease symptoms of aortic valve stenosis. However, the only way to eliminate aortic valve stenosis is surgery to repair or replace the valve and open up the passageway.
However, surgery isn't always needed right away. If tests reveal that you have mild to moderate aortic valve stenosis and you have no symptoms, there's generally no need for immediate valve surgery. Instead, your doctor will talk with you about scheduled checkups to carefully monitor the valve so that surgery can be done at the appropriate time. Your doctor will also prescribe antibiotics before dental work to reduce the risk of endocarditis. The same approach is usually taken with infants and children with mild to moderate aortic valve stenosis.
In general, the appropriate time for surgery is when narrowing becomes severe and signs and symptoms develop. If at any point you notice signs and symptoms associated with aortic valve stenosis, let your doctor know so that your valve can be evaluated.
Some people never develop severe aortic valve stenosis, so they never need surgery. For others, the condition progresses and surgery is necessary.
No medications can eliminate aortic valve stenosis. However, your doctor may prescribe certain medications to help your heart, such as ones to control heart rhythm disturbances associated with aortic valve stenosis.
If you have aortic valve stenosis, your doctor will recommend that you take antibiotics before certain dental or medical procedures, to prevent the heart infection endocarditis.
Surgery is the primary treatment for aortic valve stenosis. Surgical procedures to treat aortic valve stenosis include :
- Aortic valve replacement. This is by far the most common surgical treatment for aortic valve stenosis. In this type of surgery, surgeons remove the narrowed aortic valve and replace it with a mechanical valve or a tissue valve from a pig, cow or human-cadaver donor. Mechanical valves are made from metal and are durable, but they carry the risk of blood clots forming on or near the valve. If you receive a mechanical aortic valve, you must take an anticoagulant medication for life. Tissue valves, such as those from a pig, cow or human cadaver, rarely raise your risk of blood clots, but they tend to wear out faster than mechanical valves. Another type of tissue valve replacement is autograft, in which your own pulmonary valve — another heart valve — is used to replace the aortic valve. Replacement of the aortic valve involves open-heart surgery, performed with general anesthesia. Through an incision the length of your breastbone (sternum), your heart is exposed and connected to a heart-lung machine that assumes your breathing and blood circulation functions during the procedure. The narrowed aortic valve is then repaired or replaced.
- Aortic valve repair. Occasionally, repairing the aortic valve is an option. For example, some infants are born with an aortic valve in which the leaflets of the valve are fused together. Doctors can often improve the function of the valve with balloon valvuloplasty to increase the aortic valve opening. This procedure can be done as part of a cardiac catheterization and doesn't require open-heart surgery. In rare cases a surgeon may operate on the valve and separate these leaflets in a procedure called valvotomy, to reduce stenosis and improve blood flow. Or valve repair may involve removing calcium deposits on or near the valve. This helps clear the valve passageway.
- Balloon valvuloplasty. This procedure uses a soft, thin tube (catheter) tipped with a balloon to open up the aortic valve passageway. A doctor guides the catheter through a blood vessel in your elbow or groin to your heart and into the narrowed aortic valve. Once in position, a balloon at the tip of the catheter is inflated. The balloon pushes open the aortic valve and stretches the valve opening. The balloon is then deflated, and the catheter with balloon is guided back out of your body. Balloon valvuloplasty may relieve aortic valve stenosis and its symptoms, especially in infants and children. However, in adults, the procedure isn't usually successful, and the valve tends to narrow again even after initial success. For these reasons, doctors rarely use balloon valvuloplasty today to treat aortic valve stenosis in adults, except in patients who are too sick to undergo surgery.
Aortic valve stenosis can be treated effectively with surgery. However, you may still be at risk of irregular heart rhythms even after you've been treated for aortic valve stenosis. You may need to take medications to lower that risk.
Some possible ways to prevent aortic valve stenosis include :
- Take steps to prevent rheumatic fever. You can do this by making sure you see your doctor when you have a sore throat. Untreated strep throat can develop into rheumatic fever. Fortunately, strep throat is easily treated with antibiotics.
- Prevent endocarditis. You can help prevent this infection of your aortic valve and inner heart by taking antibiotics before certain dental and medical procedures. Ask your doctor when you should take antibiotics to prevent endocarditis.
- Address risk factors for coronary artery disease. These include high blood pressure, obesity and high cholesterol levels. These factors have been linked to the progression of aortic valve stenosis, so it's a good idea to keep your weight, blood pressure and cholesterol levels under control if you have aortic valve stenosis.
Once you know that you have aortic valve stenosis, your doctor may recommend that you limit strenuous activity to avoid overworking your heart.
If you're a woman of childbearing age with aortic valve stenosis, discuss pregnancy and family planning with your doctor before you become pregnant. Your heart works harder during pregnancy. How a heart with aortic valve stenosis tolerates this extra work depends on the degree of stenosis and how well your heart pumps. Should you become pregnant, you'll need evaluation by your cardiologist and obstetrician throughout your pregnancy, labor and delivery, and after delivery.