Heart Valves and Valve Disease

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.

• The mitral valve - between the left atrium and the left ventricle.
• The tricuspid valve - between the right atrium and the right ventricle.
• The pulmonary valve - between the right ventricle and the pulmonary artery (the main artery that takes blood from the heart to the lungs to collect oxygen).
• The aortic valve - between the left ventricle and the aorta (the main artery that takes oxygen-rich blood from the heart to the body).

The valves make sure that when the atria or ventricles contract, the blood flows the correct way through the heart and into the arteries.

See separate leaflet called 'How the Heart Works' for more details on the function of the heart and how the heart beats.

What is heart valve disease?

A valve that is diseased or damaged can affect the flow of blood through the heart. There are two main types of valve problem:

• Valve stenosis. This means that the opening of the valve is narrowed and the valve does not open fully. So, there is some restriction in blood flow through the valve.
• Valve regurgitation (sometimes called valve incompetence, or a 'leaky valve'). This means that the valve does not close properly and there is backflow of blood through the leaky valve.

Any of the valves can be affected by these problems. However, the mitral and aortic valves are the ones that most commonly become diseased. There are separate leaflets that give details of mitral stenosis, mitral regurgitation, aortic stenosis, and aortic regurgitation.

What are the symptoms of heart valve disease?

Basically, the more narrow or leaky a valve is, the greater the problem is likely to be. Some minor narrowing or leakiness may cause no problems or symptoms. However:

• If the narrowing is severe - the heart has to pump harder to get blood past the narrowing.
• If leakiness is severe - the heart has to pump harder to pump the blood that leaks back, in addition to the normal amount of blood flowing through the heart.

In both cases, this can put a 'strain' on the heart. There may be an increase in pressure behind the affected valve. This back pressure can cause blood and fluid to build up in the lungs or lower part of the body (depending on which valve is affected).

The symptoms that may develop include:

• Shortness of breath. Mainly on exertion at first, but may occur at rest if it is more severe.
• Tiredness, dizziness or episodes of fainting.
• Abnormal heart rhythms which can cause palpitations and other problems.
• Swelling of tissues due to fluid congestion.
• Chest pain or angina. This may occur if there is not enough blood flow to the coronary arteries (the arteries that take blood to the heart muscle).

Various complications may develop, depending on the valve affected and the severity of the problem.

What causes heart valve disease?

Rheumatic heart disease

This is the most common cause of valve problems. Rheumatic heart disease is a general term which means any heart problem which develops after having an episode of rheumatic fever.

Rheumatic fever is a condition which sometimes follows an infection with a bacterium called the streptococcus. Your body makes antibodies to the bacterium to clear the infection. But, in some people, the antibodies also 'attack' various parts of the body, in particular, the heart valves. Inflammation of one or more valves may develop which can cause permanent damage and lead to thickening and scarring years later.

Rheumatic fever used to be common in the UK in the era before antibiotics, but it is now rare. It is still quite common in some developing countries.

Other causes

Other causes of valve disease include:

• Deposits of calcium ('calcification') in parts of the valve. This is the commonest cause of aortic stenosis in older people.
• A 'floppy' valve is a common cause of mild mitral valve regurgitation.
• Some congenital heart problems. It is then usually part of a complex heart deformity.
• Infection of the valve (endocarditis).
• A complication of various uncommon diseases.

What is the treatment for heart valve disease?

If the narrowing or leakiness is mild, and you have no symptoms, then you usually do not need any regular treatment. If you develop symptoms or complications, various medicines may be advised to ease the symptoms. Surgery to stretch, repair or replace the valve may be needed in some cases. Surgical treatment has greatly improved the outlook for many cases of severe valve disease. Surgery has a very good success rate.

Heart valve disease and endocarditis

If you have a diseased valve then endocarditis is a possible complication. Endocarditis is an infection of the valve. (Damaged valves are more prone to infection than normal valves.) Unless promptly treated, endocarditis can cause serious illness. See leaflet called 'Infective Endocarditis' for details.

If you have a diseased heart valve, 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' kills bacteria which may get into the bloodstream and helps to prevent endocarditis. Most doctors who do surgical procedures are aware of the need to advise 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 and antibiotic cover to prevent endocarditis

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. Helpfor 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.

Further 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