The CentriMag centrifugal blood pump is a newly developed ventricular assist device based on magnetically levitated bearingless rotor technology. A combined computational and experimental study was conducted to characterize the hemodynamic and hemocompatibility performances of this novel blood pump. Both the three-dimensional flow features of the CentriMag blood pump and its hemolytic characteristics were analyzed using computational fluid dynamics (CFD)-based modeling. The hydraulic pump performance and hemolysis level were quantified experimentally. The CFD simulation demonstrated a clean and streamlined flow field in the main components of the CentriMag blood pump. The predicted results by hemolysis model indicated no significant high shear stress regions in the pump. A comparison of CFD predictions and experimental results showed good agreements. The relatively large gap passages (1.5 mm) between the outer rotor walls and the lower housing cavity walls provide a very good surface washing through a secondary flow path while the shear stresses in the secondary flow paths are reduced, resulting in a low rate of hemolysis ([Normalized Index of Hemolysis] NIH = 0.0029 +/- 0.006) without a decrease of the pump's hydrodynamic performance (pressure head: 352 mm Hg at a flow rate of 5.0 L/min and a rotational speed of 4,000 rpm).

The Levitronix UltraMag blood pump is a next generation, magnetically suspended centrifugal pump and is designed to provide circulatory support for pediatric and adult patients. The aim of this study is to investigate the hemodynamic and hemolytic characteristics of this pump using the computational fluid dynamics (CFD) approach. The computational domain for CFD analysis was constructed from the three-dimensional geometry (3D) of the UltraMag blood pump and meshed into 3D tetrahedral/hybrid elements. The governing equations of fluid flow were computationally solved to obtain a blood flow through the blood pump. Further, hemolytic blood damage was calculated by solving a scalar transport equation where the scalar variable and the source term were obtained utilizing an empirical power-law correlation between the fluid dynamic variables and hemolysis. To obtain mesh independent flow solution, a comparative examination of vector fields, hydrodynamic performance, and hemolysis predictions were carried out. Different sizes of tetrahedral and tetrahedral/hexahedral mixed hybrid models were considered. The mesh independent solutions were obtained by a hybrid model. Laminar and SST κ-ω turbulence flow models were used for different operating conditions. In order to pinpoint the most significant hemolytic region, the flow field analysis was coupled to the hemolysis predictions. In summary, computational characterization of the device was satisfactorily carried out within the targeted operating conditions of the device, and it was observed that the UltraMag blood pump can be safely operated for its intended use to create a circulatory support for both pediatric and adult-sized patients.

For the need for respiratory support for patients with acute or chronic lung diseases to be addressed, a novel integrated maglev pump-oxygenator (IMPO) is being developed as a respiratory assist device. IMPO was conceptualized to combine a magnetically levitated pump/rotor with uniquely configured hollow fiber membranes to create an assembly-free, ultracompact system. IMPO is a self-contained blood pump and oxygenator assembly to enable rapid deployment for patients requiring respiratory support or circulatory support. In this study, computational fluid dynamics (CFD) and computer-aided design were conducted to design and optimize the hemodynamics, gas transfer, and hemocompatibility performances of this novel device. In parallel, in vitro experiments including hydrodynamic, gas transfer, and hemolysis measurements were conducted to evaluate the performance of IMPO. Computational results from CFD analysis were compared with experimental data collected from in vitro evaluation of the IMPO. The CFD simulation demonstrated a well-behaved and streamlined flow field in the main components of this device. The results of hydrodynamic performance, oxygen transfer, and hemolysis predicted by computational simulation, along with the in vitro experimental data, indicate that this pump-lung device can provide the total respiratory need of an adult with lung failure, with a low hemolysis rate at the targeted operating condition. These detailed CFD designs and analyses can provide valuable guidance for further optimization of this IMPO for long-term use.

To provide respiratory support for patients with lung failure, a novel compact integrated pump-oxygenator is being developed. The functional and biocompatibility performances of this device are presented. The pump-oxygenator is designed by combining a magnetically levitated pump/rotor with a uniquely configured hollow fiber membrane bundle to create an assembly free, ultracompact, all-in-one system. The hemodynamics, gas transfer and biocompatibility performances of this novel device were investigated both in vitro in a circulatory flow loop and in vivo in an ovine animal model. The in vitro results showed that the device was able to pump blood flow from 2 to 8 L/min against a wide range of pressures and to deliver an oxygen transfer rate more than 300 mL/min at a blood flow of 6 L/min. Blood damage tests demonstrated low hemolysis (normalized index of hemolysis [NIH] approximately 0.04) at a flow rate of 5 L/min against a 100-mm Hg afterload. The data from five animal experiments (4 h to 7 days) demonstrated that the device could bring the venous blood to near fully oxygen-saturated condition (98.6% +/- 1.3%). The highest oxygen transfer rate reached 386 mL/min. The gas transfer performance was stable over the study duration for three 7-day animals. There was no indication of blood damage. The plasma free hemoglobin and platelet count were within the normal ranges. No gross thrombus is found on the explanted pump components and fiber surfaces. Both in vitro and in vivo results demonstrated that the newly developed pump-oxygenator can achieve sufficient blood flow and oxygen transfer with excellent biocompatibility.

A miniature Maglev blood pump based on magnetically levitated bearingless technology is being developed and optimized for pediatric patients. We performed impeller optimization by characterizing the hemodynamic and hemocompatibility performances using a combined computational and experimental approach. Both three-dimensional flow features and hemolytic characteristics were analyzed using computational fluid dynamics (CFD) modeling. Hydraulic pump performances and hemolysis levels of three different impeller designs were quantified and compared numerically. Two pump prototypes were constructed from the two impeller designs and experimentally tested. Comparison of CFD predictions with experimental results showed good agreement. The optimized impeller remarkably increased overall pump hydraulic output by more than 50% over the initial design. The CFD simulation demonstrated a clean and streamlined flow field in the main flow path. The numerical results by hemolysis model indicated no significant high shear stress regions. Through the use of CFD analysis and bench-top testing, the small pediatric pump was optimized to achieve a low level of blood damage and improved hydraulic performance and efficiency. The Maglev pediatric blood pump is innovative due to its small size, very low priming volume, excellent hemodynamic and hematologic performance, and elimination of seal-related and bearing-related failures due to adoption of magnetically levitated bearingless motor technology, making it ideal for pediatric applications.