Infective endocarditis

Infective endocarditis

This is caused by microbial infection of a heart valve (native or prosthetic), the lining of a cardiac chamber or blood vessel, or a congenital anomaly (e.g. septal defect).
The causative organism is usually a bacterium, but may be a rickettsia, chlamydia or fungus.

Infective endocarditis typically occurs at sites of preexisting endocardial damage, but infection with particularly virulent or aggressive organisms (e.g. Staphylococcus aureus) can cause endocarditis in a previously normal heart
staphylococcal endocarditis of the tricuspid valve
is a common complication of intravenous drug misuse

Many acquired and congenital cardiac lesions are vulnerable to endocarditis, particularly areas of endocardial damage caused by a high-pressure jet of blood,
such as ventricular septal defect, mitral regurgitation and aortic regurgitation, many of which are haemodynamically insignificant.
In contrast, the risk of endocarditis at the site of haemodynamically important low-pressure lesions, such as a large atrial septal defect, is minimal.