Effect of the design modifications on the hemocompatibility and hydrodynamic performance of FDA-approved blood pump at various operating conditions

Purpose: The use of CFD as a tool to assess the safety of medical devices, particularly in the context of hemocompatibility, remains constrained due to the absence of standardized validation and evaluation methods. This limitation hinders the comparability and reliability of simulation studies, crucial for ensuring the hemodynamics within ventricular assist devices (VAD) which have vital importance in numerous cardiovascular cases. To address this gap, FDA-approved blood pump is considered as a baseline design and numerically investigated with the purpose to reveal the hemodynamics and hydrodynamic performances of the modified blades. Methods: Intensive validation steps, encompassing mesh independence and time step sensitivity tests, are conducted to establish the appropriate mesh structure and time step for further CFD simulations. Comparison with measurements and hemolysis results from literature shows the importance of adequate validation. Modifications to the baseline pump design, including blade aspect ratio, camber angle, and blade number, are examined in terms of hemodynamics and hydrodynamics. Results: Results are complemented with correlations from literature to evaluate hemodynamics for combinations of various designs and operating conditions. The blade aspect ratio emerges as a pivotal design parameter, influencing both hemolysis rate and pump characteristics curves, followed by blade number and camber angle. It was revealed that the effect of the blade aspect ratio on hemolysis rate is strong because reduced blade passage constricts the flow near the inlet, making it the most dominant parameter on hemocompatibility and hydrodynamic performance of the blood pump. At 2500 and 3500 rpm, and flow rates ranging from 2.5 to 6 lpm, the study demonstrates that 2-bladed rotor configuration yields decreased hemolysis rates while maintaining comparable pump performance to the baseline configuration. Conclusion: These findings underscore that with an adequate validation process, CFD can be utilized in guiding the design alterations and evaluation of blood pumps, offering cost-effective and flexible alternatives to traditional and in vivo testing methodologies. As the CFD studies have shown, appropriate blade geometry will assist in achieving the desired hemocompatibility and hydrodynamic performance according to demand.