Heart valve

A structure at the exit of a heart chamber that allows blood to flow out of the chamber, but prevents backwash. There are 4 heart valves: aortic, pulmonary, mitral, and tricuspid. Their opening and closing during each heart cycle produces heart sounds. Any of the 4 heart valves may be affected by stenosis (narrowing), which causes the heart to work harder to force blood through the valve, or by incompetence or insufficiency (leakiness), which makes the valve unable to prevent backwash of blood. These defects cause characteristic heart murmurs. Heart-valve defects may be present at birth (see heart disease, congenital), or they may be acquired later in life. The most common congenital valve defects are aortic stenosis and pulmonary stenosis. Acquired heart-valve disease is usually the result of degenerative changes or ischaemia affecting part of the heart and leading to aortic stenosis or mitral incompetence. Rheumatic fever can cause mitral stenosis, mitral incompetence, aortic valve defects, tricuspid stenosis and tricuspid incompetence. The heart valves may also be damaged by bacterial endocarditis. Heart-valve disorders commonly lead to heart failure, arrhythmias, or symptoms resulting from reduced blood supply to body tissues. Heart-valve defects may be diagnosed by auscultation, chest X-ray, ECG, or echocardiography and may be corrected by heart-valve surgery.