Key result
Carotid stenosis throat shows ~4.7-fold higher wall shear stress than healthy upstream segments.
Absolute Event Rate: 107% vs 23%
p-value: p=<0.02
Patient-specific computational fluid dynamic analysis demonstrates that severe carotid stenoses create highly complex spatiotemporal variations in wall shear stress that vastly exceed forces captured in idealized geometric models.
Markedly elevated WSS at carotid stenosis may promote instability; hypothesis-generating and requires in vivo validation before clinical use.
Hemodynamic forces play a role in determining endothelial cell (EC) phenotype and influence vascular remodeling. We present a lesion-based computational fluid dynamic (CFD) pilot analysis to understand the complex spatial and temporal hemodynamic changes that prevail in patients with high-grade carotid artery stenosis (CS). High-resolution three-dimensional (3D) rotational angiography datasets were acquired in eight patients, and used to generate computational meshes. CFD analysis was carried out implementing realistic shear-dependent viscosity for blood. The mean wall shear stress (WSS) within the stenosis region was 107 ± 73 dyn/cm(2) rapidly followed by direction reversal and lower oscillating values in the recirculation zone at a mean of 19 ± 14 dyn/cm(2). WSS vectors exhibited complex dynamic directional and amplitude oscillations not seen in healthy segments, along with time-dependent convergence and divergence strips during the cardiac cycle. The spatial gradient of WSS revealed an elevated average magnitude at the throat of the stenosis of 1425 ± 1012 dyn/cm(3). In conclusion, patient-based CFD analysis of CS predicts a complex hemodynamic environment with large spatial WSS variations that occur very rapidly over short distances. Our results improve estimates of the flow changes and forces at the vessel wall in CS and the link between hemodynamic changes and stenosis pathophysiology.
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Schirmer et al. (2012) studied High-grade symptomatic carotid artery stenosis (n=8). Computational fluid dynamic (CFD) modeling of stenosis vs. Healthy CCA segment upstream was evaluated on Mean wall shear stress (WSS) (p=<0.02). Patient-based computational fluid dynamic analysis predicted a mean wall shear stress of 107 ± 73 dyn/cm² at the stenosis throat compared to 23 ± 11 dyn/cm² in the healthy upstream segment (P<0.02).
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