Inside the human heart there are four, thin membranes (valves) that open and close automatically to regulate blood flow. A normal heart valve will beat up to 6 billion times in an average lifetime.

The aortic valve and pulmonary valve control blood flow out of the ventricles to other parts of the body. The mitral valve and the tricuspid valve control blood flow from the atria to the ventricles.

A variety of conditions exist that can affect the performance of heart valves. These include:

• Degenerative valve disease (the most common form of valve disease, usually affecting the mitral valve)
• Coronary artery disease (plaque in the arteries)
• Congenital abnormalities (heart defects)
• Calcification due to aging (hardening of the arteries)
• Rheumatic fever and bacterial endocarditis (infections)

When heart valve disease is present, it may cause a back-flow of blood through the valve (regurgitation) or a narrowing of the valve that results in reduced blood flow (stenosis). If your disease is significant enough to affect the performance of your heart, your doctor may recommend valve replacement surgery.

When the valve does not work properly any more, the symptoms become so severe for the patient to bear that it is necessary to repair or to replace the heart valve. Quality of life is severely compromised and can only be restored by valve surgery.

Stenosis
If one of the two basic requirements guaranteed by a healthy heart valve (correct amount of blood let through and no regurgitation) is no longer satisfied, the heart starts having problems. If the valve leaflets become stiff, the valve does not open fully, thus not letting enough blood pass through. In this case, it is said that the valve is stenotic.
One of the main causes for stenosis is calcification of the valve. It can be congenital, being due to rheumatic fevers, infection or bacterial endocarditis. Except for the former, calcification affects the valve leaflets, thickening and stiffening them. When the tissue starts being more rigid, there is a greater accumulation of calcium deposits, which again reduces the flexibility of the valve cusps.
When a valve is stenotic, the heart has to exert a stronger force in order to push the blood outside the chambers. As a consequence, the ventricle walls become thicker over time. This abnormal condition is not good for the heart: it can lead to blood stagnation in the heart chamber and to the consequent formation of blood clots.

Regurgitation
If the valve does not close properly or if it closes too slowly, it lets some blood flow back. The valve is said to be regurgitant (or insufficient, or incompetent). A heart valve becomes regurgitant because of infection, bacterial endocarditis, rheumatic fever or coronary artery disease. Infection is the cause of damage to the valve leaflets: holes in the leaflets or in the valve perimeter can cause paravalvular leakage or leaflet stiffening, which hampers proper coaptation. Coronary artery disease prevents the heart muscles from being properly nourished, and this causes problems in the closure of the mitral and tricuspid valve. The heart has to work twice as hard to pump the same quantity of blood. The heart chambers receive blood back, and therefore the heart chambers dilate in order to store the increased

Symptoms of heart valve disease
The type and severity of heart valve disease symptoms depend on which of the four valves is affected, and how severely.
If the valve disease is mild there may be no symptoms. If it is more serious, the symptoms can include:

• tiredness
• shortness of breath or breathlessness after light exertion
• palpitations (irregular, fluttery heartbeat)
• chest pain (angina) due to the lack of blood in the heart's blood vessels
• swelling of the ankles or feet
• dizziness
• fainting

Diagnosis
The General Practitioner will listen to the description of your symptoms and will carry out a physical examination. He or she will listen to your heartbeat with a stethoscope and check whether a murmur can be heard: a murmur is an extra noise that can be caused by blood flow through a damaged valve.
If your General Practitioner thinks something should be investigated in greater depth, he may refer you to a heart specialist in order to conduct more specific tests, such as:

• an echocardiogram. This is an ultrasound scan that gives an image of the inside of the heart
• a chest X-ray
• an electrocardiogram (ECG). This records the electrical signals occurring in the heart
• an angiogram. This gives a picture of the blood flow through the heart. A dye, which shows up on X-rays, is injected into the heart by means of a small tube and X-rays are taken.

Surgery
When the option of valve replacement is chosen, the surgery consists in removing the native valve and replacing it with a prosthesis. There are three different types of prostheses: mechanical, biological and homograft.
When the option of valve repair is chosen, the valve itself and/or the subvalvular apparatus are surgically modified. In the case of mitral and tricuspid valves, an annuloplasty band or ring can be implanted on the annulus. This is a ring-shaped device, which is sutured around the annulus. This device provides shape and support to the annulus, restoring the natural function to the valve.