[Massive mitral valve insufficiency caused by thrombosis in a Björk-Shiley prosthesis. Report of a case].

This is a case of a 25 year old male with rheumatic heart disease who after 8 months of mitral valve replacement developed bacterial endocarditis complicated by severe valve malfunction due to a thrombus in the valve ring. The patient was correctly anticoagulated since the time the valve replacement, it was felt that the infection was responsible for the thrombus formation. The patient was reoperated and the valve changed for another of the same size and model. The need for prompt diagnosis and surgical intervention is emphasized in cases of prosthesis malfunction.