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

Abstract

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: see text]) in different components of the pump was investigated. [Formula: see text] was found to be more sensitive to positive incidence angles ([Formula: see text]) compared with negative incidence angles in rotors. Negative incidence angles had little impact on [Formula: see text] both in rotors and the outlet guide vanes. The improved cardiac function made only a minor difference in [Formula: see text] (estimated average [Formula: see text] 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: see text] by 47.97%, remarkably increasing the blood damage potential. Conclusion: This study revealed the relationship between the blade incidence angle [Formula: see text] and [Formula: see text], and recommended negative-incidence-angle blade designs as it yielded lower [Formula: see text]. 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.