ABSTRACT
Infective endocarditis (IE; B) results from bacterial-vegetation of heart valves. Acute IE has a time course of days and is usually caused by Staphylococcus aureus in intravenous drug users; both sides of the heart can be affected, but the right heart is most commonly affected, because the lungs filter out many organisms, so that the left side of the heart gets less exposure to organisms. Subacute IE has a time course of weeks/months and is generally secondary to Streptococcus viridans infection after dental procedures; only abnormal valves are affected and hence these are more likely to be on the left side of the heart because those valves are more commonly damaged as they are on the high pressure side of the heart. Perforation of the valve leaflets and rupture of papillary muscles may lead to aortic or mitral regurgitation.
