Impeller Position in a Magnetically Levitated Rotodynamic Blood Pump and Its Impact on In-Silico Hemocompatibility

Abstract

In magnetically levitated rotodynamic blood pumps (RPBs), the impeller position depends on a balance of electromagnetic and fluid dynamic forces. The aim of this study was to describe the impeller position of the HeartMate 3 over a wide range of operating conditions and assess its potential impact on hemocompatibility. Three-dimensional impeller positions were measured using a transparent HeartMate 3 pump casing, laser distance measurements, and a high-speed camera. Accompanying computational fluid dynamic (CFD) hemocompatibility predictions of a displaced and centered impeller at a typical operating point were compared. Impeller positions vary substantially with different operating points with a maximum axial displacement of 223 µm at 7 L/min and 7,000 rpm and a maximum radial displacement of 145 µm at 0 L/min and 7,000 rpm. In CFD, a displaced impeller had only a minor influence on global pump parameters (<2%) at an operating point of 5 L/min and 6,000 rpm. However, deviations in local flow metrics of up to 9% were observed compared with a centered impeller simulation. We here provide the impeller position of the HeartMate 3 over the full operating range (0-9 L/min, 3,000-7,000 rpm) to support further research, including more extensive CFD simulations.