A Strain-Based Model for Mechanical Hemolysis Based on a Coarse-Grained Red Blood Cell Model

Abstract

Mechanical hemolysis is a major concern in the design of cardiovascular devices, such as prosthetic heart valves and ventricular assist devices. The primary cause of mechanical hemolysis is the impact of the device on the local blood flow, which exposes blood elements to non-physiologic conditions. The majority of existing hemolysis models correlate red blood cell (RBC) damage to the imposed fluid shear stress and exposure time. Only recently more realistic, strain-based models have been proposed, where the RBC's response to the imposed hydrodynamic loading is accounted for. In the present work we extend strain-based models by introducing a high-fidelity representation of RBCs, which is based on existing coarse-grained particle dynamics approach. We report a series of numerical experiments in simple shear flows of increasing complexity, to illuminate the basic differences between existing models and establish their accuracy in comparison to the high-fidelity RBC approach. We also consider a practical configuration, where the flow through an artificial heart valve is computed. Our results shed light on the strengths and weaknesses of each approach and identify the key gaps that should be addressed in the development of new models.

A Review of Hemolysis Prediction Models for Computational Fluid Dynamics

“…Since Arora et al introduced this hemolysis model, there have been two different extensions proposed by two other groups considering additional hemolysis mechanisms, leading to even more complex representations. The first extension, described by Ezzeldin et al , replaces the droplet representation by a coarse‐grained molecular model of the RBC membrane. The shape distortion of Eq.…”

The variational multiscale formulation for the fully‐implicit log‐morphology equation as a tensor‐based blood damage model

“…Arwatz and Smits [10] derived a scalar viscoelastic blood damage model, yet the generalisation to three-dimensional flows is not clear. Other strain-based approaches were proposed by Ezzeldin et al [11] and Sohrabi and Liu [12]. Ezzeldin et al [11] compute the deformation of a high-fidelity RBC model based on a membrane energy composed of four contributions.…”

“…Both works (Refs. [11,12]) describe the red blood cell membrane accurately but rely on a Lagrangian description, which can be biased by the choice of the tracers. Furthermore, it is computationally too costly to apply these methods to large-scale simulations such as those required for whole blood pumps.…”

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

“…Nesta vertente, a abordagem para o termo de produção da hemólise também é lagrangeana, e também apresenta os problemas já citados alguns parágrafos antes. Finalmente, há uma outra frente de proposição de modelagem matemática para quantificação da hemólise que, sem se basear no modelo de lei de potências, abordam diretamente as alterações físicos-químicas das hemácias durante os processos de formação e/ou aumento de poros, deformação e ruptura de membranas, liberação de hemoglobina, e distorções morfológicas (Vitale et al, 2014), (Ezzeldin et al, 2015), (Sohrabi e Liu, 2016). Justamente por incorporarem descrições matemá-ticas de fenômenos em escala micrométrica, tais modelos acabam por apresentar custos computacionais (tempo de processamento e quantidade de memória alocada) ainda inviáveis mesmo para os dias de hoje e, por isso são empregados em estudos com escalas menores que as de interesse na área de dispositivos médicos.…”

“…A vantagem do modelo baseado em deformação é que ele pode modelar o processo de relaxamento da membrana viscoelástica da hemácia, o que não é possível usando um modelo baseado em tensão mecânica (Arora et al, 2004), (Chen e Sharp, 2011), (Arwatz e Smits, 2013), (Ezzeldin et al, 2015), (Hariharan et al, 2015).…”