The Design and Evaluation of a Portable Extracorporeal Centrifugal Blood Pump

Numer Methods Biomed Eng

et al. 2022

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.

Section: Discussionmentioning

confidence: 99%

Section: Cfd Methodsmentioning

confidence: 99%

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

Numer Methods Biomed Eng

et al. 2022

“…The Reynolds‐averaged Navier–Stokes (RANS) equations were solved using the commercial software Ansys CFX (ANSYS Inc., Canonsburg, PA, USA), which employs a finite‐volume method based on discretization of the governing equations. The convective terms were solved in high‐resolution form and the SST k‐ω turbulence model 20,64 was employed for stabilization simulations 21,66 . The frozen rotor interface was placed downstream of the trailing edge of the blades as the interface between the rotating region (impeller, clearances, and secondary flow passage) and the stagnant region (inlet pipe and volute).…”

Section: Methodsmentioning

confidence: 99%

“…The convective terms were solved in high-resolution form and the SST k-ω turbulence model 20,64 was employed for stabilization simulations. 21,66 The frozen rotor interface was placed downstream of the trailing edge of the blades as the interface between the rotating region (impeller, clearances, and secondary flow passage) and the stagnant region (inlet pipe and volute). A mass flow rate of 0.088 kg/s (obtained from the volume flow rate of 5 L/min) boundary condition was set at the inlet and static pressure (0 mm Hg) boundary condition was set at the outlet.…”

Section: Cfd Methodsmentioning

confidence: 99%

Impact of volute design features on hemodynamic performance and hemocompatibility of centrifugal blood pumps used in ECMO

et al. 2022

Artificial Organs

Background The centrifugal blood pump volute has a significant impact on its hemodynamic performance hemocompatibility. Previous studies about the effect of volute design features on the performance of blood pumps are relatively few. Methods In the present study, the computational fluid dynamics (CFD) method was utilized to evaluate the impact of volute design factors, including spiral start position, volute tongue radius, inlet height, size, shape and diffuser pipe angle on the hemolysis index and thrombogenic potential of the centrifugal blood pump. Results Correlation analysis shows that flow losses affect the hemocompatibility of the blood pump by influencing shear stress and residence time. The closer the spiral start position of the volute, the better the hydraulic performance and hemocompatibility of the blood pump. Too large or too small volute inlet heights can worsen hydraulic performance and hemolysis, and higher volute inlet height can increase the thrombogenic potential. Small volute sizes exacerbate hemolysis and large volute sizes increase the thrombogenic risk, but volute size does not affect hydraulic performance. When the diffuser pipe is tangent to the base circle of the volute, the best hydraulic performance and hemolysis performance of the blood pump is achieved, but the thrombogenic potential is increased. The trapezoid volute has poor hydraulic performance and hemocompatibility. The round volute has the best hydraulic and hemolysis performance, but the thrombogenic potential is higher than that of the rectangle volute. Conclusion This study found that the hemolysis index shows a significant correlation with spiral start position, volute size, and diffuser pipe angle. Thrombogenic potential exhibits a good correlation with all the studied volute design features. The flow losses affect the hemocompatibility of the blood pump by influencing shear stress and residence time. The finding of this study can be used to guide the optimization of blood pump for improving the hemodynamic performance and hemocompatibility.

“…Reynolds-averaged Navier–Stokes (RANS) equations were solved using the commercial software Ansys CFX (ANSYS Inc., Canonsburg, PA, USA), which employs a finite-volume method, based on discretization of governing equations. The convective terms were solved in high-resolution form, and the SST k-ω turbulence model [ 18 , 20 ] was employed for stabilization simulations [ 21 , 22 ]. In addition, a normal artery without an intravascular pump (no-pump case) was analyzed, to calculate the normal/base levels, as the control group for evaluating the effect of adding an intravascular pump, in which the blood was considered as laminar flow.…”

Section: Methodsmentioning

confidence: 99%

The Impact of a New Arterial Intravascular Pump on Aorta Hemodynamic Surrounding: A Numerical Study

et al. 2022

Bioengineering

Purpose: The purpose of this study was to investigate the impact of a new arterial intravascular pump on the hemodynamic surroundings within the aorta. Methods: A new arterial intravascular pump was placed in the descending aorta, and the effects of three positions within the aorta, as well as the number (n = 1 to 3) of pumps, on arterial flow features, organ perfusion, and blood trauma were investigated using a computational fluid dynamics (CFD) method. Results: It was found that as the pump position was moved backward, the perfusion in the three bifurcated vessels of the aorta arch increased and the pump suction flow decreased, resulting in a reduced high shear stress and decreased residence time in the three branches of the aortic arch. The further posterior the location of the pump, the better the blood flow perfusion to the kidneys, while the perfusion at the bifurcation of the abdominal aorta was reduced, due to the pump suction effect. Compared to the condition with single pump support, the multi-pump assist model can significantly reduce the pump rotating speed, while keeping the same flow patterns, leading to a decreased volume of high shear stress and flow loss. When increasing the number of pumps, the perfusion to the three branches of the aortic arch increased, accompanied by a diminished residence time, and the perfusion to the other aortic branches was decreased. However, the perfusion to the other aortic branches, especially for the renal arteries and even under a three-pump condition, was close to that without pump assistance. Conclusion: The placement of an intravascular pump near the beginning of the suprarenal abdominal aorta was considered the optimal location, in order to improve the hemodynamic surroundings. Increasing the number of pumps can significantly reduce the rotational speed, while maintaining the same flowrate, with a decreased fluid energy loss and a reduced high shear stress. This arterial intravascular pump can effectively improve renal blood flow.