The impact of rotor configurations on hemodynamic features, hemocompatibility and dynamic balance of the centrifugal blood pump: A numerical study

Abstract

To investigate the effect of rotor design configuration on hemodynamic features, hemocompatibility and dynamic balance of blood pumps. Computational fluid dynamics was employed to investigate the effects of rotor type (closed impeller, semi‐open impeller), clearance height and back vanes on blood pump performance. In particular, the Eulerian hemolysis model based on a power‐law function and the Lagrangian thrombus model with integrated stress accumulation and residence time were applied to evaluate the hemocompatibility of the blood pump. This study shows that compared to the closed impeller, the semi‐open impeller can improve hemolysis at a slight sacrifice in head pressure, but increase the risk of thrombogenic potential and disrupt rotor dynamic balance. For the semi‐open impeller, the pressure head, hemolysis, and axial thrust of the blood pump decrease with increasing front clearance, and the risk of thrombosis increases first and then decreases with increasing front clearance. Variations in back clearance have little effect on pressure head, but larger on back clearance, worsens hemolysis, thrombogenic potential and rotor dynamic balance. The employment of back vanes has little effect on the pressure head. All back vanes configurations have an increased risk of hemolysis in the blood pump but are beneficial for the improvement of the rotor dynamic balance of the blood pump. Reasonable back vanes configuration (higher height, wider width, longer length and more number) decreases the flow separation, increases the velocity of blood in the back clearance, and reduces the risk of blood pooling and thrombosis. It was also found that hemolysis index (HI) was highly negatively correlated with pressure difference between the top and back clearances (r = −.87), and thrombogenic potential was positively correlated with pressure difference between the top and back clearances (r = .71). This study found that rotor type, clearance height, and back vanes significantly affect the hydraulic performance, hemocompatibility and rotor dynamic balance of centrifugal blood pumps through secondary flow. These parameters should be carefully selected when designing and optimizing centrifugal blood pumps for improving the blood pump clinical outcomes.

A multi-constituent model for assessing the effect of impeller shroud on the thrombosis potential of a centrifugal blood pump

“…The results validated that there was a unimodal effect of top clearance size on thrombus formation in the blood pump, which was also found in previous study. 10 There are some limitations in this study. Firstly, boundary condition was set to a constant flow rate rather than pulsatile flow.…”

“…This result was also observed in previous studies by stress accumulation method. 10 The main reason was that semi-shroud impeller increased the exposure of blood to SSS above 9, 50, and 150 Pa. This led to an increase in average SSS of semi-shroud impeller.…”

“…The results validated that there was a unimodal effect of top clearance size on thrombus formation in the blood pump, which was also found in previous study. 10…”

“…This method mainly focused on the effect of blood washing out and cannot analyze thrombosis distribution induced by shear stress. Li et al 10,11 analyzed the effect of different rotor structures on the thrombogenic potential based on weighted statistic of stress accumulation(SA) and residence time(RT). The author found that closed-shroud impeller can reduce thrombogenic potential compared to the semi-shroud impeller.…”

In-Vitro Flow Validation of Third-Generation Ventricular Assist Devices: Feasibility and Challenges

“…Additionally, this increased resistance to backflow in the bottom gap is further amplified by the four struts incorporated for impeller connection to the torque measuring shaft. The potential impact of modified bottom clearance gaps on local flow patterns and blood trauma prediction was also systematically studied by Li et al 22 showing a reduced bottom clearance gap to reduce the numerically predicted blood trauma potential.…”