Simulation of shearing destruction of red blood cells

Many medical devices used to treat heart failure generate non-physiologic shear flow. This can trigger red blood cell destruction following implantation of cardiac assist devices (VADs), artificial heart valves, vascular stents, or interventional thrombectomy devices.

Red blood cell destruction, or mechanical hemolysis, is an inevitable complication of interventional devices, so scientists want to gain a better understanding of the phenomenon.

in the Physics of LiquidsTsinghua University researchers developed a model of red blood cell destruction based on simulations of dissipative particle dynamics within a high-shear flow. They used the results to make recommendations for improving VADs.

“After interventional medical devices are implanted in the human body, the nearby flow field creates a shear flow with a very high shear rate,” said co-author Xiwen Zhang. “The rate of change of velocity of the fluid deforms the membrane of the red blood cells. Eventually, the deformation of the membrane exceeds the ultimate strain and the membrane is destroyed by shear flow.”

The team discovered that acceleration during shearing is an important factor in red blood cell destruction, beyond exposure time and shear stress. They recommend adding a flow buffer structure to the structural design of VADs to reduce some of the hemolysis caused by shear acceleration.

For hemolysis-related research, many researchers focus on macro-scale experiments to obtain a set of empirical fitting formulas.

“But our team studies the shear destruction process of red blood cells in more detail at the red blood cell level by using dissipative particle dynamics,” Zhang said.

A transport-dissipation particle dynamics method was developed to simulate shear damage to red blood cells in real blood. Recognition: Physics of Liquids (2022). DOI: 10.1063/5.0112967

“We hope that our study can serve as a bridge between macroscopic hemolysis experiments and microscopic simulations of red blood cells (molecular dynamics simulations),” said Zhang. “In future work, we will continue to construct multiple red blood cell shear fracture models and perform whole blood-based shear fracture simulations for comparison to macroscopic hemolysis experiments.”

Researchers are developing a new index to more accurately predict hemolysis of VADs and to help optimize the shape of VADs, which should improve hydraulic performance and reduce hemolysis.

They plan to better represent the diffusion process of hemoglobin after shear damage by adding a transport dissipation particle dynamics model based on this work.