Effect of Blade Thickness on Hemodynamics and Hemolysis: A Case Study of Pediatric Centrifugal Blood Pumps

Abstract

Blood pumps, critical components in ventricular assist devices and extracorporeal membrane oxygenation systems, are primarily evaluated based on their ability to minimize blood damage through optimized design. Despite extensive research, the impact of impeller blade thickness and the proximity of rotating and stationary surfaces remains insufficiently explored. This study presents a comprehensive analysis, combining experimentally validated numerical simulations with an advanced Lagrangian approach, to compare the hemodynamic and hemolytic performance of three centrifugal pumps. These pumps share identical volutes but differ in impeller blade thickness. The selected operating point—a blood flow rate of 1 l/min and a pressure differential of 60 mm Hg—was chosen for its clinical relevance, particularly in pediatric applications. Computational fluid dynamics (CFD) simulations were employed to evaluate hemodynamic performance, while Lagrangian postprocessing was used to estimate the hemolysis index (HI) by tracing fluid particle trajectories. These analyses provided detailed insights into velocity, pressure, and shear stress (SS) distributions, with special attention given to critical regions near clearance gaps and solid boundaries. The results reveal a significant increase in hemolysis risk in these regions, especially as the size of opposing rotating and stationary surfaces increases. The pump with the thickest blades (pump 3) exhibited the poorest performance, with shear stress and hemolysis index negatively impacted by the increased blade thickness. Although specific to the pumps studied, these findings offer valuable guidance for the optimal design of blood pumps and suggest that the analytical approach could be applied to other sensitivity studies.