[True aneurysm of mitral valve secondary to aortic valvular infective endocarditis].

A case of the mitral valve aneurysm with aortic valvular infective endocarditis is reported. A 30-year-old male who had the history of Streptococcus viridans endocarditis underwent aortic and mitral valve replacement. The aortic valve was bicuspid and had the perforation in its non-coronary cusp, and histology in its specimen showed post-inflammatory vascularization and disorganization of architecture. A gigantic aneurysm was visible in the anterior leaflet of the mitral valve, but both anterior and posterior leaflets had no inflammatory change in histology. In this case, the "jet" of blood produced by aortic valve perforation involved the mitral valve. This aneurysmal change was so called "jet lesion" secondary to aortic valve endocarditis.