Endocarditis is an infection in the endocardium (the inner lining of the heart muscle, which also covers the heart valves) in which the endocardium becomes damaged and bacteria stick to the heart valves or heart lining. The endocardium lines all four chambers of the heart which blood passes through as the heart beats. It also covers the four valves, which normally open and close to allow the blood to flow in only one direction through the heart during each contraction. For the heart to pump blood efficiently, the four chambers must contract and relax, and the four valves must open and close, in a well coordinated fashion. Endocarditis can interfere with the heart's ability to do its job. The endocardium can be damaged and made more susceptible to infection by heart defects that are present at birth, such as mitral valve prolapse, in which blood leaks through a...