Numerical analysis of different cardiac functions and support modes on blood damage potential in an axial pump

Background: Cardiac functions and support modes of left ventricular assist device (LVAD) will influence the pump inner flow field and blood damage potential. Methods: Computational fluid dynamics (CFD) method and lumped-parameter-model (LPM) were applied to investigate the impacts of cardiac functions under full (9000 rpm) and partial (8000 rpm) support modes in an axial pump. Results: The constitution of hemolysis index ((Formula presented.)) in different components of the pump was investigated. (Formula presented.) was found to be more sensitive to positive incidence angles ((Formula presented.)) compared with negative incidence angles in rotors. Negative incidence angles had little impact on (Formula presented.) both in rotors and the outlet guide vanes. The improved cardiac function made only a minor difference in (Formula presented.) (estimated average (Formula presented.) in one cardiac cycle) by 9.88%, as the flow rate expanded mainly to higher flow range. Switching to partial support mode, however, would induce a periodic experience of severe flow separation and recirculation at low flow range. This irregular flow field increased (Formula presented.) by 47.97%, remarkably increasing the blood damage potential. Conclusion: This study revealed the relationship between the blade incidence angle (Formula presented.) and (Formula presented.), and recommended negative-incidence-angle blade designs as it yielded lower (Formula presented.). Moreover, to avoid flow range below 50% of the design point, careful evaluations should be made before switching support modes as weaning procedures in clinical applications.