Aortic valve replacement in von Willebrand's disease.

A patient with von Willebrand's disease having aortic valve replacement was managed with cryoprecipitate infusions and monitoring of factor VIII levels. This disorder is associated with low factor VIII levels and abnormal platelet function. There may be no history of bleeding, as the severity of the bleeding tendency varies greatly and fluctuates temporally. The partial thromboplastin time is frequently prolonged, but more detailed studies are necessary to establish a diagnosis (bleeding time, platelet adhesiveness to glass beads and ristocetin, von Willebrand's antigen, ristocetin-von Willebrand's factor, and factor VIII clotting activity). Elevation of factor VIII levels to 50 to 100% of normal allows adequate clotting and is best accomplished with cryoprecipitate or fresh frozen plasma rather than commercial concentrates of factor VIII, whose activity is unpredictable.