Heart valve disease

Diseased valves may be replaced

Heart valve disease usually develops over time, affecting people aged 60 or over, but it can be the result of an infection which "chews up" the valve in a matter of days.

The condition is often present at birth (congenital heart disease), the child being born with valves made of two parts rather than the usual three. Gradually the valve wears and becomes thicker to the point where it has to be replaced.

Rheumatic fever used to be a common cause, but as the illness is now rare the effect of bacteria in damaging the valve, preventing it opening or closing properly, is now rare.

Acute infection (endocarditis), sometimes as a result of an abcess of a tooth, is however still a common cause of valve disease. Bacteria can destroy the valve in as little as a week.

Flow of blood

If one or more of the four heart valves are diseased or damaged it can affect the flow of blood in two ways.

If the valve does not open fully, it obstructs the flow of blood - known as valve stenosis.

If the valve does not close properly, it will allow blood to leak backwards - called valve incompetence or valve regurgitation.

Both stenosis, a narrowing which makes the heart pump faster to get blood past the obstruction, and incompetence, which means the heart has to do more to pump the required volume of blood forwards, put extra strain on the heart.

The blood behind the affected valve will also be under increased pressure, called back pressure, leading to a build-up of fluid in the lungs or lower part of the body, depending on the valve affected.

Symptoms include tiredness or breathlessness when exercising, swelling of the ankles and legs, dizziness or fainting in extreme cases. Angina can occur.

Short of breath

Professor Gianni Angelini, British Heart Foundation professor of cardiac surgery at the University of Bristol, said: "You will have a patient who goes to see the GP and says suddenly he has noticed he is short of breath.

"He can't do things he was able to do before. He can't climb up stairs without getting short of breath, without having to stop."

An electrocardiogram of the heart will be taken followed by an echocardiogram to give a picture of the heart.

If valve disease is found, treatment with drugs - including diuretics, ACE inhibitors and digoxin - may be used to control the problem, or - in severe cases - heart valve replacement may be necessary.

Diseased valves are usually replaced by manufactured valves (artificial/mechanical valves) or animal valves (tissue valves or biological valves).

There is a 5% chance of a patient dying after valve replacement surgery. Risks are less for aortic valve replacement.