HYDRODYNAMIC AND HEMODYNAMIC DESIGN IMPROVEMENT OF THE MAGNETICALLY LEVITATED HEARTQUEST LVAD

Abstract

The HeartQuest LVAD is a magnetically levitated blood pump featuring an unshrouded centrifugal impeller and open blood flow journal within the magnetic gap. Both in-vitro and CFD analysis have shown that flow demonstrates increased residence time, flow separation, and reversal at off-design conditions. This study investigated design improvements, specifically to the impeller and volute, that would both shift and widen the optimal operating conditions of this pump. All other features of the device, including the magnetic subsystems, impeller diameter, inlet volute, and outlet cannula dimensions were not changed. The design improvement was performed with our CFD-based design optimization tool. The impeller, volute, and diffuser were optimized with a high-performance hydrofoil profile replacing the inner profile of the current design and with gradually changed sectional areas of the diffuser. Extensive CFD analyses show that the best efficiency point of the new design was shifted to approximately 5.5lpm from original 9.0lpm and the magnitude of maximal efficiency was increased significantly with a lower level of predicted hemolysis. Within a wider flow rage, CFD results revealed that there are no unfavorable reverse flow and separation in the diffuser between 2.0 and 8.0lpm. These results demonstrate the value of hemodynamic optimization to improve the favorable operating range of a turbodynamic blood pump.