Aortic stenosis is a narrowing of the aortic valve in the heart. This restricts blood flow through the valve. The heart then needs to contract harder to pump blood into the aorta. Mild narrowing may not cause symptoms. More severe narrowing can cause symptoms and may lead to heart failure. Surgery to stretch or replace the valve may be needed.
Understanding the heart
The heart has four chambers - two atria and two ventricles. The walls of these chambers are mainly made of special heart muscle. During each heartbeat both of the atria contract first to pump blood into the ventricles. Then both ventricles contract to pump blood out of the heart into the arteries. There are one-way valves between the atria and ventricles, and between the ventricles and the large arteries coming from the heart. The valves make sure that when the atria or ventricles contract, the blood flows in the correct direction.
What is the aortic valve and what is aortic stenosis?
The aortic valve lies between the left ventricle and the aorta. The aorta is the main artery that takes blood from the heart to the body. The aortic valve has three flaps (cusps). Blood flows through the valve when the left ventricle contracts at the early part of the heartbeat. When the left ventricle relaxes, the aortic valve closes. Then the mitral valve opens to allow more blood into the ventricle ready for the next heartbeat.
Aortic stenosis means that when the aortic valve opens, it does not open fully. It is narrowed (stenosed) when it is open. Therefore, there is a partial restriction of blood flow from the left ventricle into the aorta. Basically, the more narrowed the valve, the less blood that can get through, the more severe the problem is likely to be. In some cases, aortic stenosis occurs at the same time as aortic regurgitation. (See separate leaflet called Aortic Regurgitation.)
What are the causes of aortic stenosis?
Age-related calcification of the valve
This is a common cause. Deposits of calcium build up in the valve in some older people. It is not clear why this happens. This calcification makes the valve stiff and open less easily. It can be mild and cause little narrowing. However, in time it can become more severe. About 1 in 20 people aged over 65 have some degree of this type of aortic stenosis.
Rheumatic fever is a condition that sometimes occurs during an infection with a bacterium (germ) called the streptococcus. Your body makes antibodies to the bacterium to clear the infection. However, in some people the antibodies also attack various parts of the body, in particular the heart valves. Inflammation of a valve may develop. This can cause permanent damage and lead to thickening and scarring years later.
Other causes of aortic stenosis are uncommon and include:
- Some congenital heart problems. It is then usually part of a complex heart deformity.
- Infection of the valve (endocarditis).
- An abnormality of the tissues just above or just below the valve. This may cause a narrowing and restrict blood flow, and cause problems identical to stenosis of the valve.
What are the symptoms of aortic stenosis?
- If the valve is only mildly narrowed you are not likely to have any symptoms.
- If the narrowing becomes worse the left ventricle has to work harder to pump blood into the aorta. The wall of the ventricle becomes thickened (hypertrophied). Symptoms that may then develop include:
- Dizziness and faints (especially on exertion) due to the restricted blood supply.
- Chest pain (angina) when you exert yourself. This occurs because of the increased need for oxygen by the thickened ventricle and because of reduced blood flow to the coronary arteries.
- Irregular heartbeat which you may feel as palpitations.
- If the narrowing is severe the left ventricle may not function properly and you can develop heart failure. This causes shortness of breath, tiredness, and fluid build-up in various tissues of the body. (See separate leaflet called Heart Failure.)
What are the possible complications of aortic stenosis?
- Heart failure may become severe and life-threatening.
- Endocarditis is an uncommon complication. This is an infection of the valve. Abnormal valves are more prone than normal valves to infection. Unless promptly treated, endocarditis can cause serious illness. (See separate leaflet called Infective Endocarditis.)
How is aortic stenosis diagnosed?
- A doctor may hear a heart murmur or other abnormal noises when listening with a stethoscope. Murmurs and noises are due to blood passing through abnormal valves, or to abnormal movement of valves. Aortic stenosis causes typical murmurs and noises.
- A chest X-ray may show some calcification around the aortic valve.
- An electrocardiogram (ECG) can show that the left ventricle is thickened.
- An echocardiography can confirm the diagnosis. This is an ultrasound scan of the heart.
- Cardiac catheterisation is sometimes done to assess the severity of the stenosis. In this test a thin tube called a catheter is inserted into the main blood vessel in the top of the leg. It is passed up to the heart. A small device on the tip of the catheter can measure the pressure on either side of the aortic valve. The difference in pressure gives an indication of the severity of the narrowing.
What are the treatments for aortic stenosis?
If the narrowing is mild and you have no symptoms then you may not need any treatment. If you develop symptoms or complications, various medicines may be advised to ease the symptoms. However, surgery is usually advised in most cases when symptoms develop. This is because studies have shown that once symptoms develop, the average survival is two to three years if the valve remains stenosed (narrowed). With surgery, the outlook is very good.
Medication may be advised to help ease symptoms of heart failure if heart failure develops. For example:
- Angiotensin-converting enzyme (ACE) inhibitors are medicines which help to reduce the amount of work the heart does and can ease symptoms of heart failure.
- Diuretics (water tablets) usually help if you are breathless. They make the kidneys produce more urine. This gets rid of excess blood and fluid which, with heart failure, may build up in the lungs or other parts of the body.
An operation to fix aortic stenosis is a commonly done procedure. It has a very good chance of a success. The possible options include the following:
- An operation to widen the valve (valvotomy). This requires open heart surgery.
- Valve replacement. This also requires open heart surgery. The replacement may be with a mechanical or a tissue valve. Mechanical valves are made of materials which are not likely to react with your body, such as titanium. Tissue valves are made from treated animal tissue, such as valves from a pig.
- Stretching the stenosed valve (balloon valvuloplasty). This is an option that is sometimes considered. This does not require open heart surgery. How it is done is that a thin tube called a catheter is inserted into the main blood vessel in the top of the leg. It is passed up to the heart. The tip of the catheter is placed in the aortic valve opening. A balloon at the tip of the catheter is then inflated to stretch the narrowed valve. However, for adult patients, balloon valvuloplasty tends to be used only in those who are unsuitable for valvotomy or valve replacement surgery. This is because the improvement in the flow across the valve (following balloon valvuloplasty) does not usually last for very long. Valvotomy or valve replacement surgery tends to give better long-term results.
If you need surgery, a surgeon will advise on which is the best option for your situation.
Antibiotics to prevent endocarditis
People with heart valve problems used to be given antibiotics before some dental treatments and some surgical operations. However, the National Institute for Health and Clinical Excellence (NICE) no longer recommends that they be taken routinely for any of these procedures. Antibiotics are now only offered to people who have an infection at the time of the operation.
Good oral and dental hygiene are also thought to be important in helping to prevent infective endocarditis. In particular, if you have any condition which increases your risk of developing infective endocarditis (see above), you should not let any dental problems such as a dental abscess or gum disease go untreated. These dental conditions increase the chance of bacteria getting into the bloodstream.
What is the prognosis (outlook) for people with aortic stenosis?
Some cases are mild and cause no symptoms. If you develop symptoms they tend to become worse over the years. Medication may ease symptoms, but cannot reverse a narrowed valve. Surgery is normally advised if you develop symptoms.
Surgical treatment has greatly improved the outlook in most people who have more severe stenosis. Surgery to widen or to replace the valve has a very good success rate. The outlook is good if the valve is treated before the heart becomes badly damaged.
Further help & information
Dr Tim Kenny
Dr Colin Tidy
Dr Hayley Willacy