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 or '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 and 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 the 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.
Rheumatic fever
Rheumatic fever is a condition that sometimes occurs during an infection with a bacterium (germ) called the streptococcus. You 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 which can cause permanent damage and lead to thickening and scarring years later.
Other causes
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?
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 to infection than normal valves. 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.
Medication
Medication may be advised to help ease symptoms of heart failure if heart failure develops. For details see separate leaflet called 'Heart Failure'. For example:
- 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 may build up in the lungs or other parts of the body with heart failure.
Surgical treatments
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 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 tend 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
You will normally be advised to take a short course of antibiotics if you have certain surgical procedures such as cystoscopy or colonoscopy. During these procedures, some bacteria may be 'pushed' into the bloodstream. The 'antibiotic cover' aims to kill any bacteria which may get into the bloodstream and helps to prevent endocarditis (described above). Most doctors who do these surgical procedures are aware of the need to recommend antibiotic cover to people with heart valve disease. The British Heart Foundation (contact details below) also lists a range of procedures that require antibiotic cover.
Dental treatments: until recently, it has also been advised that people with heart valve disease should take antibiotic cover when they have dental treatment. However, a guideline published in 2006 from the British Society for Antimicrobial Chemotherapy (BSAC) says that this is not needed in most situations. Their information aimed at patients says:
"A BSAC group of experts has spent a lot of time carefully looking at whether dental treatment procedures are a possible cause of infective endocarditis (IE) [sometimes called bacterial endocarditis (BE)], which is infection of the heart valve. After a very detailed analysis of all the available evidence they have concluded that there is no evidence that dental treatment procedures increase the risk of these infections.
Therefore it is recommended that the current practice of giving patients antibiotics before dental treatment be stopped for all patients with cardiac abnormalities, except for those who have a history of healed IE, prosthetic heart valves and surgically constructed conduits.
The main reasons for this are the lack of any supporting evidence that dental treatment leads to IE and the increasing worry that administration of antibiotics may lead to other serious complications such as anaphylaxis (severe allergy) or antibiotic resistance.
The advice from the BSAC is that patients should concentrate on achieving and keeping a high standard of oral and dental health, as this does reduce the risk of endocarditis. Help for this will be provided by your Dental Professional."
However, this guideline is controversial. It has caused a lot of debate, especially from some cardiologists (heart doctors) and dentists who maintain that antibiotic cover is still needed for dental procedures. See references below for details of some articles that deal with this controversy. Your own doctor or dentist will advise for your own particular circumstance.
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.
Surgical treatment has greatly improved the outlook in most people who have more severe stenosis. Surgery to widen or 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 sources of help and information
British Heart Foundation
14 Fitzhardinge Street, London, W1H 6DH
Tel - Heart Information Line: 08450 70 80 70
Web: www.bhf.org.uk
References
© EMIS and PIP 2004 Updated: August 2007 CHIQ Accredited
