ABSTRACT
Thromboses of valvular prostheses represent a rare but serious complication for mechanical valves, and are sometimes fatal. Obstructive thromboses present an immediate threat to life, while the more common, more insidious, non-obstructive thromboses are essentially manifested by thrombo-embolic events. These thromboses often occur at times of insufficient anticoagulation, especially during the first post-operative year and during treatment breaks for non-cardiac surgery, an increasingly common situation. The therapeutic management of an 'obstructive' thrombosis is above all surgical. However, fibrinolysis represents an effective alternative, although it does present a not insignificant risk of systemic embolism (in the order of 10 to 15%). The main indications for fibrinolysis are thromboses of right heart valves, and for left heart prostheses, patients in a very unstable haemodynamic state, remoteness from a cardiac surgery centre, any surgical contraindications, and cases where a large thrombus has been excluded by trans-oesophageal ultrasound. In cases of contraindications to both surgery and fibrinolysis, treatment with heparin might be proposed, but without any great hopes of completely unblocking the prosthesis. Treatment of a 'non-obstructive' thrombosis is primarily medical: optimising anticoagulation with intravenous heparin, or even the addition of aspirin. When the thrombus is large and mobile, surgery should be envisaged if medical treatment fails.
