What Is Endocarditis? Endocarditis (EN-do-kar-DI-tis) is an infection of the inner lining of the heart chambers and valves. This lining is called the endocardium (en-do-KAR-de-um). The condition also is called infective endocarditis (IE). The term endocarditis also is used to describe an inflammation of the endocardium due to other conditions. This article only discusses endocarditis related to infection. IE occurs if bacteria, fungi, or other germs invade your bloodstream and attach to abnormal areas of your heart.