Mechanical and surgical bioprosthetic valve thrombosis.

Abstract

Valve thrombosis can occur in mechanical prosthetic valves and is increasingly recognised in transcatheter and surgically implanted bioprosthetic valves. The risk of thrombosis of mechanical valves is higher in the mitral position compared with aortic position and in older generation valves (ball and cage valves). There is a wide spectrum of presentation from the asymptomatic patient to those with embolic complications or cardiogenic shock. A combination of transthoracic and transesophageal echocardiography is required to assess the haemodynamic effect of thrombosis (valve gradients and area), leaflet motion and thrombus size. CT or cinefluoroscopy may be useful in selected cases to assess leaflet motion or help identify the aetiology of valve obstruction where echocardiography is inconclusive. Exclusion of pannus or vegetation is important. Management of non-obstructive thrombus is primarily optimisation of anti-coagulation. Treatment of obstructive thrombus requires a decision between slow, low-dose fibrinolysis or valve surgery. Factors which need to be considered include thrombus size, New York Heart Association Class, presence of concomitant coronary artery disease or other valve dysfunction, surgical risk and contraindication to fibrinolysis. This review examines the incidence, aetiology, clinical features, imaging algorithms and management of prosthetic valve thrombosis.