Endocarditis is an inflammation of your heart's inner lining. The most common type, bacterial endocarditis, occurs when germs enter your heart. These germs come through your bloodstream from another part of your body, often your mouth. Bacterial endocarditis can damage your heart valves. If untreated, it can be life-threatening. It is rare in healthy hearts.
Risk factors include having an abnormal or damaged heart valve, a severe case of mitral valve prolapse, an artificial heart valve or certain heart defects.