On the Optimization of a Centrifugal Maglev Blood Pump Through Design Variations.

Peng Wu,Chengke Yin,Shu Li,Jiadong Huo,Wei-Tao Wu,Weifeng Dai

doi:10.3389/fphys.2021.699891

Abstract

Centrifugal blood pumps are usually designed with secondary flow paths to avoid flow dead zones and reduce the risk of thrombosis. Due to the secondary flow path, the intensity of secondary flows and turbulence in centrifugal blood pumps is generally very high. Conventional design theory is no longer applicable to centrifugal blood pumps with a secondary flow path. Empirical relationships between design variables and performance metrics generally do not exist for this type of blood pump. To date, little scientific study has been published concerning optimization and experimental validation of centrifugal blood pumps with secondary flow paths. Moreover, current hemolysis models are inadequate in an accurate prediction of hemolysis in turbulence. The purpose of this study is to optimize the hydraulic and hemolytic performance of an inhouse centrifugal maglev blood pump with a secondary flow path through variation of major design variables, with a focus on bringing down intensity of turbulence and secondary flows. Starting from a baseline design, through changing design variables such as blade angles, blade thickness, and position of splitter blades. Turbulent intensities have been greatly reduced, the hydraulic and hemolytic performance of the pump model was considerably improved. Computational fluid dynamics (CFD) combined with hemolysis models were mainly used for the evaluation of pump performance. A hydraulic test was conducted to validate the CFD regarding the hydraulic performance. Collectively, these results shed light on the impact of major design variables on the performance of modern centrifugal blood pumps with a secondary flow path.

Highlights

In recent years, ventricular assist devices (VAD, called blood pumps) have gradually replaced heart transplantation as an effective treatment for heart failure (Bellumkonda and Bonde, 2012; Molina and Boyce, 2013; Magruder et al, 2016; Cui et al, 2018; Gaffey et al, 2018; Kawabori et al, 2018; Shahreyar et al, 2018)
Concerning blood compatibility, this study only considers hemolysis
This study shows that an extension of the splitter blade toward upstream decreased turbulence intensity and hemolysis level

Summary

Introduction

Ventricular assist devices (VAD, called blood pumps) have gradually replaced heart transplantation as an effective treatment for heart failure (Bellumkonda and Bonde, 2012; Molina and Boyce, 2013; Magruder et al, 2016; Cui et al, 2018; Gaffey et al, 2018; Kawabori et al, 2018; Shahreyar et al, 2018). Turbulence and secondary flow will further increase the blood damage (Wu et al, 2020). Mechanical bearings result in friction and heating, bringing secondary damage to blood; the flow dead zone around mechanical bearing increases thrombosis risk. Maglev bearings avoid mechanical contact, friction and dynamic sealing; it can avoid blood damage and flow dead zone. The clearance of Maglev bearing is can be wide, resulting in low stress, reduced blood damage and good biocompatibility. Sobieski et al (2012) conducted hemolysis tests of the maglev blood pump Centrimag and Maquet Rotaflow which uses mechanical bearings, found that the hemolysis level of Centrimag is higher than Rotaflow for two test conditions. The secondary flow intensity would increase considerably, and hemolytic performance is not as low as one might be expected for a maglev blood pump (Sobieski et al, 2012). There have been some studies that proposed hemolysis models to account for turbulence effects (Wu et al, 2019, 2020), the credibility of hemolysis prediction in turbulence remains an open question

Objectives

Methods

Results

Discussion

Conclusion