Review article: unexpected bleeding in the operating room: the role of acquired von Willebrand disease.Anesth Analg 2012; 114(1):73-81A&A
Acquired von Willebrand disease (AvWD) is a rare bleeding disorder that occurs in association with a variety of underlying disorders and can lead to unforeseen bleeding in surgical patients. Cardiovascular as well as malignant and immunological diseases may be associated with AvWD, and several pathophysiological mechanisms have been proposed. von Willebrand factor (vWF) is a plasma glycoprotein that mediates platelet adhesion to subendothelial collagen and causes platelet aggregation under high shear stress. Additionally, vWF acts as a specific carrier for coagulation factor VIII (FVIII) in the plasma. AvWD results from a reduced rate of vWF synthesis, an increased rate of vWF removal, or a final generation of lower-molecular-weight, less active subunits or multimers. In contrast to inherited von Willebrand disease patients, who are characterized by lifelong bleeding episodes, AvWD patients present with a sudden onset of bleeding symptoms, which can induce acute bleeding episodes during critical surgical procedures. Typically, no family history of bleeding is found. The clinical visualization of AvWD is similar to that of the hereditary form with mucocutaneous bleeding and increased perioperative bleeding, ranging from mild to severe bleeding. Laboratory evaluation of AvWD is mainly based on the measurement of vWF activity and antigens as well as on the multimeric analysis of vWF. A variety of therapeutic approaches have been used depending on the underlying disease and pathophysiological mechanisms. Treatment options to control acute hemorrhages or to prevent bleeding complications during surgery include desmopressin, FVIII/vWF concentrates, high-dose IV immunoglobulins, and plasma exchange. Because the half-life of vWF is reduced in AvWD, high doses of FVIII/vWF concentrates administered at frequent intervals may be necessary during bleeding episodes. In cases of unresponsiveness to standard therapy, recombinant activated factor VIIa may be an alternative option. However, the most effective therapy is the resolution of the underlying disease. In the present review, we focus on the current understanding of AvWD, outlining the associated disorders, underlying pathophysiological mechanisms, and possible treatment options.