The success of current heart valve surgery is largely due to the development of valve prostheses to replace damaged native valves. Since 1960, when Starr performed the first successful mitral valve replacement with a caged ball prostheses [2], some 60 different prosthesis have been developed in 30 years. Most prostheses fall within two broad categories: mechanical (ball, disc or bileaflet valves) and biological (porcine, pericardial and homografts). There is no perfect replacement valve and different complications may develop in patients in whom artificial valves are implanted, regardless of their type. Among the so-called valve-related complications, thrombo-embolic events associated with mechanical valves represent an ever-present risk which requires lifelong meticulous anticoagulation with its attendant risk of anticoagulation-related haemorrhage. Thromboembolic complications can present in two ways: either as systemic embolism (cerebral, brachial, femoral ) or as thrombosis of the valve itself.