Hemodynamic remodeling of the carotid bifurcation after endarterectomy
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Carotid artery stenosis (CAS) is a contributor to ischemic stroke, and its progression is influenced by local hemodynamic conditions beyond diameter reduction. This follow-up case study presents a computational analysis of geometric and hemodynamic remodeling before and after carotid endarterectomy (CEA) in two individuals, using CTA-derived vascular reconstructions. Computational fluid dynamics simulations were performed with patient-specific inflow waveforms and Windkessel outlet boundary conditions. Plaque components were projected onto the luminal surface for localized evaluation of wall shear stress (WSS) metrics. Established quantities derived from the WSS field (TAWSS, OSI, RRT, ECAP), and topology-derived descriptors (WSS divergence, TSVI) were assessed to characterize mechanobiological stimuli associated with atherosclerosis [1-3]. CEA altered lumen geometry and pressure-drop characteristics. In the patch-reconstructed case, stenosis removal eliminated the pressure gradient but generated an enlarged bulb region associated with distributed low-WSS and oscillatory environments. In the second case, a residual stenosis maintained a reduced pressure drop and preserved localized disturbed flow in the ICA bulb. Luminal data distributions showed that post-CEA TAWSS decreased and OSI became more dispersed in both cases, indicating a redistribution rather than normalization of the shear environment. Regions of elevated ECAP emerged following patch enlargement, suggesting increased susceptibility to oscillatory low-shear exposure. Although lumen-wide divWSS remained centered near zero, plaque-projected regions showed a persistent negative shift, indicating preferentially heterogeneous contracting WSS-traction patterns over plaque. TSVI was nonnegative and unimodal; in Case 1 it shifted post-CEA from a concentrated low-variability regime toward a broader, higher-variability distribution while retaining a similar high-end tail. These findings demonstrate that surgical reconstruction modifies hemodynamic conditions and that flow features strongly influence post-intervention biomechanical risk markers. Integrating classical and topology-based WSS metrics provides insight into the mechanistic links between vascular remodeling and endothelial mechanotransduction.
