[Late occlusive thrombosis of mitral prosthesis with sinus rhythm. Report of two surgically treated patients].

Two cases are reported of late occlusive thrombosis of a mitral bioprosthesis with sinus rhythm. Two men were concerned (40 and 54 years of age), hospitalized for acute pulmonary oedema which was resistant to medical treatment, 3 years after replacement of a mitral valve (Carpentier Edwards No. 31 and Liotta No. 25). Catheterization showed that in both cases there was an average transmitral holodiastolic gradient greater than 25 mmHg. Emergency surgery revealed two anatomical forms of occlusive thrombosis: in one case, a localized red thrombus hindered the opening of a valve cusp; in the other, exuberant fibrin deposits lined the ventricular face of the valve cusps. There were no signs of degeneration of the bioprostheses and, in particular, there was no calcification. Both patients were asymptomatic 1.5 years and 3 years respectively after their operations. Late occlusive thromboses of mitral bioprostheses are exceptional (13 detailed cases collected from the literature).