A New Mathematical Model for Assessment of Bleeding and Thrombotic Risk in Three Different Types of Clinical Ventricular Assist Devices

In this study, our new shear-induced thrombosis and bleeding mathematical model (integrates variations in platelet and vWF morphology, function, and binding ability) was utilized to identify regions at high risk of induced blood damage and assess the bleeding and thrombosis risk in three different types of clinical ventricular assist devices (VADs) (HVAD, CentriMag and HeartMate II). It was found that extracorporeal VADs require a higher pressure head to overcome body and pipeline resistance compared to intracorporeal VADs. Centrifugal VADs have a better work ability compared to axial VADs. In vitro VADs are more highly blood damaged than in vivo VADs. For bleeding probability, CentriMag > HVAD > HeartMate II. Narrow regions of the VAD (such as the hydrodynamic clearance in HVAD, the side clearance in CentriMag and the blade tip clearance in HeartMate II) contribute significantly to device-induced bleeding. For thrombotic potential, CentriMag > HeartMate II > HVAD. The distribution of regions of high thrombotic potential in VADs is similar to the distribution of long residence time regions (such as the clearance between rotor and guide cone in HVAD, the back clearance and impeller eye in CentriMag, and the straightener and rotor inlet in HeartMate II). Flow separation regions in VADs resulting in residence time and shear stress pairs also contributed to the risk of bleeding and thrombosis. Further studies found that the hemocompatibility of VADs was strongly negatively correlated with efficiency (r < −0.80). This study found that CentriMag > HVAD > HeartMate II in terms of bleeding probability and CentriMag > HeartMate II > HVAD in terms of thrombosis potential. Narrow regions and flow separation regions in VADs contribute to blood damage. The efficiency of VADs is highly negatively correlated with hemocompatibility.