The heart normally has four valves which are thin tissue structures that open to allow blood to flow in a forward direction, but then close to prevent backward flow. A heart valve may be abnormal at birth or may become diseased from acute rheumatic fever, infection, or as a consequence of aging. Sometimes one or more valves will fail even if their structure is relatively normal. This may occur, for instance, when the heart muscle suffers from a disease process which weakens and stretches the heart chambers causing heart failure.
Diseased heart valves may become thickened and fail to open properly, causing obstruction to normal blood flow, or may fail to offer a watertight seal and thus cause blood to leak back into a heart chamber – a reverse of normal flow. These consequences can range from trivial to serious, depending on the severity of the lesion. It is often normal to see a tiny valve leak when examining the heart with Doppler echocardiography, usually imperceptible on auscultation with a stethoscope. A significant valve abnormality, however, would normally be accompanied by the presence of a heart murmur on clinical examination. Investigations with ECG, chest X-ray and sometimes other tests, including Doppler echocardiography, would be recommended if the murmur was thought to be significant. In many children and in some adults, however, a heart murmur does not necessarily imply the presence of a heart valve lesion. These murmurs are called ‘innocent murmurs’ and have no importance, but require care in assessment.
A faulty heart valve might not require specific treatment and the lesion may be simply followed over a period of time. Drug treatment to reduce the strain on the heart and valve may be required. Antibiotics are generally recommended when bacteria could cause an infection of a damaged valve (bacterial endocarditis), for example during dental treatment. A severely diseased valve, however, will usually require surgery to repair or replace the valve, especially if it were causing symptoms.