Computational prediction of mechanical hemolysis in aortic valved prostheses

The paper reports the prediction of mechanical hemolysis by three different models for the case of blood flow through aortic valved prostheses. Two of the adopted models are based on the action of instantaneous shear stress on the blood cells (stress-based), while the third accounts for the finite response time of cell deformation and relaxation (strain-based). Two aortic Dacron grafts commonly adopted in clinical practice are considered, and both are equipped with a bileaflet mechanical valve. One of the grafts reproduces the three sinuses of Valsalva, while the other is a straight tube. A direct numerical simulation approach is utilized to solve the complex fluid-structure-interaction problem and obtain detailed information of the flow patterns. To evaluate hemolysis, a large number of Lagrangian tracer particles were released at the inlet of the computational domain (upstream of the valve), and blood damage was evaluated along each trajectory for each model. We found that stress-based models predict higher levels of blood damage than the strain-based one. The same level of blood damage is observed in the two geometric configurations we considered, indicating that the adopted mechanical valve is primary risk factor for hemolysis.