Endocarditis is the inflammation of the endocardium, the thin layer of tissue cells lining the inner surface of the heart muscle and valves. This inflammation can be infectious or noninfectious. The noninfectious causes are sytemic lupus erythematosis or rheumatic fever. There they grow, destroying the lining and damaging the valves. With a bacerial cause, or bacterial endocarditis, the damage can be very severe, though it also depends on the type of bacteria since some are worse than others.
Noninfectious endocarditis can occur in anyone with an underlying inflammatory disease.
Infectious endocarditis usually occurs in people who get infected with certains types of infectious agents which cause damage to the heart valves or who already have some damage or abnormalities of their endocardium. The latter can occur in people who have had a rheumatic fever, artificial valves, or breakdown of normal valve tissue by aging or a prior episode of endocarditis. Finally, intravenous drug users and individuals receiving medication through intravenous tubes are also at risk, though this usually occurs only if the needles are dirty or if unsterile conditions exist. Once the bacteria attach themselves or gain a foothold, they begin to multiply. This in turn causes inflammation and damage the heart valve.