Hydraulic and hemodynamic performance of a minimally invasive intra-arterial right ventricular assist device

Numerical study on the performance of mixed flow blood pump with superhydrophobic surface

To meet the clinical status of the wide application of percutaneous mechanical circulatory support, this paper selects the mixed flow blood pump applied with superhydrophobic surface as the research object. The Navier slip model was used to simulate the slip characteristics of superhydrophobic surface, and the effects of the blade wrap angle and the superhydrophobic surface on the performance of the mixed flow blood pump are studied by numerical simulation. The results show that (1) considering the head, hydraulic efficiency, and hemolysis index of the blood pump, the optimal value of the blade wrap angle of the mixed flow blood pump in this paper is 60°. (2) The hydraulic efficiency of the blood pump with superhydrophobic surface is improved, and the maximum growth rate is about 13.9%; superhydrophobic surface can reduce the hemolysis index of blood pump under various working conditions, and the maximum reduction rate of hemolysis index of blood pump is 22.9%. (3) The variation trends of blood pump head, hydraulic efficiency, and hemolysis index with the increased rotating speed before and after setting superhydrophobic slip boundary conditions are the same as their original variation trends.

Numerical study on the performance of centrifugal blood pump with superhydrophobic surface

AIM

In order to reduce the blood damage of an artificial heart pump and optimize its hydraulic performance, a centrifugal blood pump with superhydrophobic characteristics is proposed in this study.

METHODS

To study the influence of superhydrophobic surface characteristics on the performance of centrifugal blood pumps, the Navier slip model is used to simulate the slip characteristics of superhydrophobic surfaces, which is realized by the user defined function of ANSYS fluent. The user defined functions with different values of slip length are verified by two benchmark solutions of laminar flow and turbulence in the pipeline. The blood pump model adopts the designed centrifugal blood pump, and its head, hydraulic efficiency and hemolysis index are calculated. The Navier slip boundary condition (a constant slip-length of 50 μm) is applied to the walls of the blood pump impeller and a volute at different positions, and the influence of the superhydrophobic surface on the performance of the blood pump at the design point Q = 6 L/min was compared and analyzed.

RESULTS

The results show that the centrifugal blood pump model used in this paper has good blood compatibility and meets the design requirements; the superhydrophobic surface can significantly reduce the scalar shear stress in the blood pump. At the design point, when the slip length is 50 μm, the mass-average scalar shear stress in the impeller area and the volute area reduction rate is about 5.9%, the hydraulic efficiency growth rate is about 3.8%, the hemolysis index reduction rate is about 18.4%, and the pressure head changes little with a growth rate of 0.3%.

CONCLUSIONS

Centrifugal blood pumps with superhydrophobic surfaces can improve the efficiency of blood pumps and reduce hemolysis. Based on these encouraging results, vitro investigations for actual blood damage would be practicable.

Effect of blade curvature on the hemolytic and hydraulic characteristics of a centrifugal blood pump

Aims:

Impeller design has a significant impact on the overall performance of a blood pump. In this study, the effect of the blade curvature was investigated by performing in silico and in vitro studies on a recently developed centrifugal blood pump.

Methods:

A computational fluid dynamics study was performed for the flow rates of 3–5 L/min at 2000 r/min. The computational fluid dynamics model was also applied on the US Food and Drug Administration (FDA) benchmark blood pump to validate our computational method. The relative hemolysis index was calculated with the Eulerian hemolysis estimation method for five impellers with the wrap angles ranging from 0° to 240°. Hydraulic experiments were conducted for the validation of computational fluid dynamics results. In addition, the curved-blade impeller (120°) and the straight-blade impeller (0°) were evaluated with in vitro hemolysis tests using human blood.

Results:

The wrap angle of 120° provided the best hydraulic and hemolytic performance. Pump achieved the physiologic operating pressures and flows with 85–115 mmHg at 2.5–5.9 L/min. Compared to the straight-blade impeller, the 120° model reduces the relative hemolysis index and the plasma-free hemoglobin near 72.8% and 56.7%, respectively. Comparison of in silico and in vitro results indicated the similar trend to the blade curvature.

Conclusion:

Introducing a blade curvature enhanced the hydrodynamic and hemolytic performance compared to the straight-blade configuration for the investigated centrifugal blood pump. The findings of this study provide new insights into centrifugal blood pump design by examining the influence of the blade curvature.

Artificial hearts-recent progress: republication of the article published in the Japanese Journal of Artificial Organs

This review was created based on a translation of the Japanese review written in the Japanese Journal of Artificial Organs in 2015 (Vol.44, No. 3, pp.130-135), with some modifications regarding several references published in 2015 or later.