[Late thromboses of prosthetic heart valves. Apropos of 15 cases]

15 patients developed late thrombosis of their prosthetic heart valves: --9 mitral, 4 tricuspid and 2 aortic valve prostheses. --12 thromboses occurred on Starr-Edwards ball prostheses (7M, 3T and 2 Ao), 2 on Starr-Edwards disc prostheses (1M, 1T) and one on a Björk-Shiley valve. 14 patients were on anticoagulant drugs but treatment was only effective in 5 patients; only 1 patient was not anticoagulated. Thrombosis of mitral and aortic valves presented with signs of pulmonary oedema and/or systemic (especially cerebral) embolism and tricuspid valve thromboses presented with signs of right heart failure or were discovered on routine examination. Paraclinical investigations, when performed, showed valve movement to be an unreliable sign but phonocardiography was useful. Differing pathological appearances were observed, either peroperatively (7 cases) or at autopsy (8 cases). Late thrombosis is a rare but dangerous complication which should be avoided by effective anticoagulation and diagnosed at an early stage.