Thrombosis of mitral valve bioprostheses in patients requiring circulatory assistance.

Two patients with new mitral valve bioprostheses required implantation of Bio-Medicus centrifugal pumps (Bio-Medicus, Minneapolis, MN) for circulatory support and had evidence of prosthetic valve thrombosis 1 and 4 days later. Both patients died of thromboembolic complications despite surgical removal of the thrombus. Thrombosis is a rare early complication of bioprosthetic valves and in these cases was probably related to low transvalvular flow due to the use of circulatory assist devices. We discuss possible strategies for avoiding and managing this catastrophic complication.