[A case of mitral valve aneurysm associated with infective endocarditis].

A case of mitral valve aneurysm associated with infective endocarditis is reported. The patient is a sixty-four year old male suffering from shortness of breath under slight exertion. He has been febrile since receiving dental treatment five months ago. The patient came to the hospital due to a continuous fever above 39 degrees C. Hematological studies suggested inflammation, and an echocardiogram revealed moderate dilatation of the left atrium, mild MR, and moderate AR. At the time of the operation, a protuberant lesion, shaped like a dome and having a size of 10 x 12 mm in diameter was found at the anterior mitral leaflet toward the left atrium. The resected specimen of the saccular lesion had a smooth surface, and the ceiling of the aneurysm was extremely thin. Microscopic study showed that the inner cavity of the lesion was covered by endothelial cells. In addition, there was granulomatous degeneration with neo-vascularization. The inferior surface of the resected valve tissue and chorda was characterized by active inflammation associated with the assembly of neutrophils and colony formation of gram-positive cocci. It was concluded that the mitral valve aneurysm was caused by weakened tissue of the anterior mitral leaflet due to sibilant inflammatory change, which resulted in protuberance of the leaflet toward the left atrium caused by left ventricular pressure.