Escherichia coli endocarditis of a native mitral valve with paravalvular pseudoaneurysm formation and fatal hemopericardium.

Until recently only few cases have been described of acute infective endocarditis with E. Coli limited to a normal native mitral valve. Furthermore, mechanisms of so called abcess formation and rupture are still uncompletely understood. We report the case of an E. Coli endocarditis developing a rapidly progressive pseudoaneurysm of the mitral annulus. At necropsy diffuse infectious tissue weakening with pseudoaneurysm formation of the mitral ring and dissection into an hemorraghic pericard were seen. The authors further discuss the changing pattern of infectious agents causing acute infective endocarditis of the native mitral valve, transesophageal echocardiographic characteristics of paravalvular cavities and insights in mechanisms of pseudoaneurysm formation and dissection from clinicopathological findings.