Introduction:
There is still insufficient to determine which carotid stenosis is likely to progress. The carotid artery shape is an independent risk factor for intimal thickening. Although it is assumed that hemodynamic factors are strongly involved in the mechanisms, the details are unknown. Here, we removed carotid plaques in unilateral carotid stenotic cases, and reproduced the vessel shape without plaques as after carotid endarterectomy, and compared hemodynamic distributions with the non-stenotic side.
Methods:
We used 30 cases of unilateral carotid stenosis (area stenosis rate > 60%) registered in the National Hospital Organization Prospective Clinical Study; Carotid CFD Study. The plaques in DICOM images were artificially removed (Figure 1), and the vessel shape without plaque was reproduced. Patient-specific arterial geometries and inflow velocities were obtained from 3D-CTA and carotid doppler examinations.We compared distributions of hemodynamic indices (time-averaged wall shear stress (WSS), time-averaged WSS gradient, normalized WSS, normalized WSS gradient, OSI and NtransWSS) at 3 regions; the stenotic site, its proximal and distal sites (10 mm).
Results and Conclusions:
The average age was 71.6 years, male 23 cases, hypertension 20, diabetes 7, dyslipidemia 15, smoking history 22, and average area stenosis rate 72.6%. Normalized WSS was lower (p<0.0001, Wilcoxon signed rank test), and NtransWSS (p=0.0242) and OSI (p=0.0355) were higher in the stenotic sites of vessels after plaque removal (Figure 2). The data suggest that low and disturbed WSS caused by differences in carotid shape may contribute to the progress in stenosis at the carotid bifurcation.
Effects of progressive carotid stenosis on cerebral haemodynamics: aortic-cerebral 3D patient-specific simulation
