Acquired von Willebrand syndrome and hemocompatibility-related adverse events in patients with left ventricular assist device

Left ventricular assist device (LVAD) is an important therapeutic option for patients with end-stage advanced heart failure. LVAD can reduce cardiovascular death and improve the quality of life in patients with end-stage advanced heart failure. However, as LVAD-implanted patients increase and survival becomes prolonged, many patients experience serious complications. Major complications of LVAD include ischemic and hemorrhagic strokes, bleeding complications, device thrombosis, right heart failure, and LVAD related infections. These complications lead to worse mortality in patients with LVAD. In particular, cerebrovascular events and gastrointestinal bleeding are the most dreaded complications. High molecule weight multimers of von Willebrand factor (vWF-HMWM) play an essential role in platelet adhesion and aggregation, but high shear stress caused by LVAD pump diminishes the vWF-HMWM. In fact, in response to the shear stress of LVAD, vWF exposes cleavage domains of ADAMTS 13 to form smaller multimeric molecules. Therefore, in many patients with LVAD, the vWF reduces its large multimers and lowers the ability to bind sufficiently to platelets and sub-endothelial collagen, resulting in the acquired von Willebrand syndrome. Thus, in LVAD patients with acquired von Willebrand syndrome, vWF function is impaired, and this impairment is associated with hemocompatibility-related adverse events. Based on hemorheology, this review focuses on the pathophysiology of acquired von Willebrand syndrome and its management in patients with LVAD.