Blood Pump Design Variations and Their Influence on Hydraulic Performance and Indicators of Hemocompatibility
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Patients with ventricular assist devices still suffer from high rates of adverse events. Since many of these complications are linked to the flow field within the pump, optimization of the device geometry is essential. To investigate design aspects that influence the flow field, we developed a centrifugal blood pump using industrial guidelines. We then systematically varied selected design parameters and investigated their effects on hemodynamics and hydraulic performance using computational fluid dynamics. We analysed the flow fields based on Eulerian and Lagrangian features, shear stress histograms and six indicators of hemocompatibility. Within the investigated range of clearance gaps (50–500 µm), number of impeller blades (4–7), and semi-open versus closed shroud design, we found association of potentially damaging shear stress conditions with larger gap size and more blades. The extent of stagnation and recirculation zones was reduced with lower numbers of blades and a semi-open impeller, but it was increased with smaller clearance. The Lagrangian hemolysis index, a metric commonly applied to estimate blood damage, showed a negative correlation with hydraulic efficiency and no correlation with the Eulerian threshold-based metric.
KeywordsComputational fluid dynamics Ventricular assist device Centrifugal blood pump Impeller design Blood damage Thrombosis Hemolysis
The authors gratefully acknowledge the financial support provided by the Swiss National Science Foundation through Grant 200021_147193 CINDY, the Marie Heim-Vögtlin fellowship PMPDP2_151255, NCCR Kidney.CH and the Stavros Niarchos Foundation. This work is part of the Zurich Heart project under the umbrella of University Medicine Zurich.
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