Endocarditis [Disease/Finding] Inflammation of the inner lining of the heart (ENDOCARDIUM), the continuous membrane lining the four chambers and HEART VALVES. It is often caused by microorganisms including bacteria, viruses, fungi, and rickettsiae. Left untreated, endocarditis can damage heart valves and become life-threatening. 1027251 M0007392 Endocarditis C2370 56819008 N0000001096 D004696 Endocarditis C0014118 Heart Diseases [Disease/Finding]