Flow‐Field Simulations and Hemolysis Estimates for the Food and Drug Administration Critical Path Initiative Centrifugal Blood Pump

Abstract

The design of blood pumps for use in ventricular assist devices, which provide life-saving circulatory support in patients with heart failure, require remarkable precision and attention to detail to replicate the functionality of the native heart. The United States Food and Drug Administration (FDA) initiated a Critical Path Initiative to standardize and facilitate the use of computational fluid dynamics in the study and development of these devices. As a part of the study, a simplified centrifugal blood pump model generated by computer-aided design was released to universities and laboratories nationwide. The effects of changes in fluid rheology due to temperature, hematocrit, and turbulent flow on key metrics of the FDA pump were examined in depth using results from a finite volume-based commercial computational fluid dynamics code. Differences in blood damage indices obtained using Eulerian and Lagrangian formulations were considered. These results are presented and discussed awaiting future validation using experimental results, which will be released by the FDA at a future date.

On the Accuracy of Hemolysis Models in Couette‐Type Blood Shearing Devices

“…Computational fluid dynamics (CFD) has been widely used in various engineering fields to solve and analyze problems that involve fluid flows . Empirical hemolysis estimation models, in conjunction with CFD simulations have been used to predict hemolysis during the development phase of VADs . Typical hemolysis models relate hemolysis to shear stresses and exposure time through a power‐law relationship …”

“…Computational fluid dynamics (CFD) has been widely used in various engineering fields to solve and analyze problems that involve fluid flows (6,7). Empirical hemolysis estimation models, in conjunction with CFD simulations have been used to predict hemolysis during the development phase of VADs (8)(9)(10)(11)(12)(13)(14)(15)(16)(17). Typical hemolysis models relate hemolysis to shear stresses and exposure time through a power-law relationship (18)(19)(20)(21)(22) where D (%) is the hemolysis index, Hb is the total hemoglobin concentration, hb represents the increase in plasma free hemoglobin, C, and are empirical constants determined by regression of the experimental data.…”

Modelagem matemática da fluidodinâmica não-newtoniana e bifásica simplificada da hemólise induzida mecanicamente em sistemas de bombeamento centrífugo de sangue

“…Além do conhecimento desses valores limiares, existe uma outra questão importante relacionada à hemólise e que ainda permanece sem resposta: até que nível de trauma mecânico (sub-hemolítico) as hemácias podem suportar sem sofrer prejuízo em seu ciclo de vida normal, isto é, sem que sua vida seja encurtada em decorrência de danos induzidos mecanicamente (Schima e Wieselthaler, 1995), (De Wachter e Verdonck, 2002), (Grigioni et al, 2004), (Heck et al, 2017), (Ozturk et al, 2017).…”

“…De maneira geral, a hemólise induzida por trauma mecânico é um processo complexo para o qual ainda se almeja um modelo matemático que possa auxiliar eficazmente durante as etapas de desenvolvimento e otimização de dispositivos médicos (Sohrabi e Liu, 2016), (Heck et al, 2017), (Yu et al, 2017). …”

“…Como este processo ocorre em escoamentos complexos, tais como aqueles no interior de sistemas de bombeamento centrífugo de sangue, não foi ainda completamente compreendido e/ou descrito cientificamente (Ozturk et al, 2016), (Heck et al, 2017).…”