Hemodynamic modeling of leukocyte and erythrocyte transport and interactions in intracranial aneurysms by a multiphase approach

Hemodynamics has been recognized as an important factor in the development, growth, and rupture of cerebral aneurysms, and investigated by computational fluid dynamics techniques using a single phase approach. However, flow-dependent cell transport and interactions are usually ignored in single phase models, in which blood is usually treated as a single phase Newtonian fluid. For getting better insight into the underlying pathology of intracranial aneurysm, cell transport and interactions should be covered in hemodynamic studies. In the present study, a multiphase hemodynamic model incorporating cell transport and interactions was developed, in which blood was modeled as multiphase fluid having a continuous phase (plasma) and two particulate phases (erythrocytes and leukocytes). The model showed good agreement with experimental data and observations in the literature, and was applied to four patient-specific aneurysms in a pulsatile manner. Leukocyte accumulations were predicted at locations with flow disturbance and low wall shear stress. The concentrations of leukocyte at accumulation sites were found to exceed 200 to 500% of normal physiological level on three unstable aneurysms, including two ruptured aneurysms and a growing aneurysm where accumulation was observed near a daughter sac and a secondary aneurysm. This suggested that aneurysms with complex secondary flow patterns could be prone to leukocyte accumulation on the wall. As this is the first study to characterize cell transport and interactions in aneurysm hemodynamics, our model can serve as a foundation for future intracranial aneurysm models.