Flow Patterns in Carotid Webs: A Patient-Based Computational Fluid Dynamics Study

Area of Science:

• Vascular Neurology
• Biomedical Engineering
• Cardiovascular Research

Background:

• Carotid webs are increasingly recognized as a cause of recurrent ischemic stroke, particularly in patients lacking other cardiovascular risk factors.
• Altered hemodynamic flow patterns near carotid webs may contribute to thrombus formation.

Purpose of the Study:

• To evaluate the hemodynamic flow patterns associated with carotid webs using computational fluid dynamics (CFD).
• To investigate the relationship between carotid web morphology and disturbed blood flow characteristics.

Main Methods:

• Utilized CFD models based on CT angiography lumen segmentations from patients with carotid webs (from the MR CLEAN trial).
• Assessed hemodynamic parameters including recirculation zone area, wall shear stress (WSS), and oscillatory shear index (OSI).
• Compared CFD-derived parameters between the carotid web and the contralateral carotid bifurcation.

Main Results:

• Significantly larger recirculation zones were observed distal to carotid webs compared to contralateral bifurcations (63 vs 43 mm²).
• Higher transverse WSS and OSI were found in recirculation zones of carotid webs.
• Time-averaged WSS was significantly higher at the minimal lumen area of the carotid web compared to the contralateral side (0.58 vs 0.45 Pa).

Conclusions:

• Carotid webs are associated with significantly disturbed flow, characterized by increased recirculation zones and elevated regional WSS metrics.
• These hemodynamic alterations suggest that carotid webs may promote thrombus formation.
• The disturbed flow patterns associated with carotid webs likely contribute to the increased risk of acute ischemic stroke.