OBJECTIVE

To evaluate the effect of different types of internal carotid artery (ICA) tortuosity on wall shear stress (WSS) in ICA and ophthalmic artery (OA), and to establish the correlation between areas of pathological WSS in these vessels with and without ICA ostial stenosis.

MATERIAL AND METHODS. A

Retrospective single-center study included 50 patients divided into 5 groups: 1) control group — normal ICA anatomy; 2) C-type ICA tortuosity; 3) S-type ICA tortuosity; 4) ICA coiling; 5) ICA kinking. All patients underwent CT angiography of supra-aortic arteries followed by 3D reconstruction and segmentation of common carotid artery, ICA and external carotid artery, as well as OA. CFD modeling was performed to calculate WSS at baseline and ICA ostial stenosis ~70%. Total areas of low (<5 Pa) shear stress zones were determined. Correlation of WSS in ICA and OA was analyzed. These values were compared between groups using descriptive statistics, correlation and ROC analysis.

RESULTS

Personalized CFD modeling revealed significantly larger areas of low WSS (<0.5 Pa) in ICA tortuosity. S-type tortuosity and kinking form the largest areas in ICA with 70% stenosis and OA. ICA ostial stenosis synergistically exacerbates hemodynamic disturbances in all groups. Correlation of low WSS areas (ICA-OA): r=0.68 (without stenosis), r=0.73 (with stenosis) (p<0.001). ROC analysis revealed moderate prognostic value of low WSS areas in ICA for predicting high hemodynamic load on OA: AUC=0.68 (without stenosis), AUC=0.73 (with stenosis).

CONCLUSION

Each type of ICA tortuosity has a different impact on hemodynamics in ICA and OA. S-type tortuosity and kinking cause the most severe hemodynamic disturbances with extensive areas of low WSS, especially when superimposed with ICA ostial stenosis. The correlation between pathological zones in ICA and OA supports hemodynamic hypothesis of ocular ischemic syndrome associated with carotid artery tortuosity. These results substantiate the need for surgical treatment of hemodynamically significant tortuosity, especially when combined with stenosis.