heart and blood vessel disorders
Infective Endocarditis
Causes of Infective Endocarditis
Bacteria (or, less often, fungi) that are introduced into the bloodstream can sometimes lodge on heart valves and infect the endocardium. Abnormal, damaged, or replacement (prosthetic) valves are more susceptible to infection than normal valves. The bacteria that cause subacute bacterial endocarditis nearly always infect abnormal, damaged, or replacement valves. However, normal valves can be infected by some aggressive bacteria, especially if many bacteria are present. Although bacteria are not normally found in the blood, an injury to the skin, lining of the mouth, or gums (even an injury from a normal activity such as chewing or brushing the teeth) can allow a small number of bacteria to enter the bloodstream. Gingivitis (inflammation of the gums) with infection, minor skin infections, and infections elsewhere in the body may introduce bacteria into the bloodstream. Certain surgical, dental, and medical procedures may also introduce bacteria into the bloodstream. Rarely, bacteria are introduced into the heart during Revascularization Procedures or Sepsis and Septic Shock , a severe blood infection, introduces a large number of bacteria into the bloodstream. When the number of bacteria in the bloodstream is large enough, endocarditis can develop, even in people who have normal heart valves. If the cause of infective endocarditis is injection of illicit drugs or prolonged use of intravenous lines (sometimes used by doctors to deliver long-term intravenous therapies for people who have serious medical conditions), the tricuspid valve (which opens from the right atrium into the right ventricle) is most often infected. In most other cases of endocarditis, the mitral valve or the aortic valve is infected. This cross-sectional view shows vegetations (accumulations of bacteria and blood clots) on the four valves of the heart. 