Cleavage and Re-Supply of von Willebrand Factor in Continuous Flow Blood Pump

Abstract

Purpose Mechanical circulatory support devices are needed to enable recovery or provide a bridge to decision for patients with heart failure. The effectiveness of extending treatment duration in this therapy was previously reported to increase adverse events, such as acquired von Willebrand disease and gastrointestinal bleeding. Blood-related damage caused by medical devices is one of the most critical parameters needed to determine the performance of medical devices. For the treatment of these complications, we considered that it is very important to analyze the relationship between the cleavage of von Willebrand factor (VWF) due to shear stress and re-supply of VWF from activated platelets during blood pump circulation. We aimed to examine the alterations in the dynamics of VWF multimers in the circulating blood during VAD therapy. Methods In this study, two types (axial and centrifugal) of implantable blood pumps and a disposable blood pump (centrifugal type) for temporary use were used. A simple mock circulation test (5L/min, 100 mmHg) was performed to investigate with both whole-blood samples and platelet-poor plasma (PPP) using fresh bovine blood. Results In an analysis based on SDS-agarose gel electrophoresis and serum VWF values (antigen and activity), high-molecular-weight multimers (HMWMs) in VWF are reduced immediately after the initiation of blood circulation using the axial flow pump, and it had plateaued 60 minutes later. On the other hand, in the study using a centrifugal pump, cleavage of the HMWMs compared to that in the case of using a centrifugal pump was very slight. Moreover, in the whole-blood sample study, HMWMs reduced once, and it had been observed to recover after 60 minutes. However, HMWMs in the PPP sample was observed to reduce continuously during a circulation test. Conclusion In this result, the dynamics of VWF within the blood pump was shown to depend on the type of the blood pump, and this study demonstrated that re-supply of VWF due to platelet activation and cleavage of VWF due to shear stress in the pump occurred at the same time by circulating within the blood pump.