Functional Assessment of Polyurethane Valve Prostheses in Calves by Transesophageal Echocardiography

Even 30 years after the first successful heart valve replacement by Harken et al. [7] and shortly afterwards by Starr and Edwards [23], the ideal heart valve prosthesis has not yet been designed [8]. Although mechanical valves are of an acceptable durability, hemolysis and valve thrombosis remain complications to be feared. Therefore, a lifelong anticoagulation therapy is required to prevent thromboembolic events. This introduces a considerable risk of serious bleeding complications, which amount to up to two or three per 100 patient-years [5, 14] but; this is however significantly lower than the risk of thromboembolic complications in patients with mechanical valves with inadequate or without anticoagulation therapy [5].