[Value and limitations of transthoracic Doppler echocardiography in the diagnosis of thromboses of mechanical valve prosthesis. Report of 19 cases].

The diagnosis of thrombosis of a valvular prosthesis is difficult especially in cases of partial thrombosis. The authors report 19 cases of partial thrombosis of mainly (16 cases) mechanical valve prostheses confirmed by radioscopy and treated either by reoperation or fibrinolysis. Mitral Valve Prostheses: 14 cases (6 Björk, 7 SJM, 1 Carbomedics). All but one case showed significant prolongation of the pressure half time compared with the postoperative reference value. In one case, however, the functional parameters of the prosthesis were normal; the diagnosis was made from the finding of a mobile thrombus on the ventricular surface of the prosthesis. Aortic Valve Prostheses: 5 cases (3 Björk, 1 SJM, 1 Duromedics). Continuous wave Doppler showed significant increases in the velocity of transprosthetic blood flow with respect to the postoperative reference values. Accurate analysis of the mobile elements of the prostheses was usually impossible. These results show that transthoracic Doppler echocardiography remains an excellent method of study and surveillance of mechanical valve prostheses but the limitations of the technique should be familiar to all operators.