Doppler ultrasound and numerical analysis for the assessment of hemodynamic disturbances in ulcerated carotid arteries

Carotid plaque ulcerations, or irregularities in plaque morphology, have been identified as an independent risk for ischemic stroke. Our previous studies using Doppler (DUS) have indicated significant flow disturbances to ulceration in the atherosclerotic carotid bifurcation, as by parameters such as turbulence intensity (TI). tools are needed to understand the implications of flow abnormalities on the risk of thrombogenesis and ischemic events. Numerical simulations using fluid dynamics (CFD) can supplement DUS studies, providing higher resolution, timeresolved of 3-D flow fields. CFD is also able to quantify factors that indicate thromboembolic or plaque potential. We report a CFD analysis of an ellipsoidal model and a matched non-ulcerated model in a moderately carotid bifurcation, with the same vessel geometries and conditions used in our previous DUS studies. The CFD used a spatial finite element discretization of over 160,000 tetrahedral elements to adequately resolve the flow . Pulsatile flow simulations with boundary conditions and waveforms matching DUS experimental conditions were for five cardiac cycles. Turbulence intensity was for the CFD models and compared with DUS results. The CFD models were able to capture in flow patterns between cardiac cycles. As observed the empirical DUS results, the CFD ulcer model displayed levels of TI in the post-stenotic region than the CFD nonulcerated . The extent and magnitude of TI was to the DUS results, after modeling for the effects of volume geometry and intrinsic spectral broadening, and a high pass filter. Furthermore, the CFD results indicate that post-stenosis is likely transitional, with both disturbed and flow present. CFD facilitates the comparison of parameters between ulcer models and may help to the risks of embolism or plaque rupture posed by atherosclerotic plaques in the carotid bifurcation.