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Shear stress in cerebral arteries carrying saccular aneurysms. A preliminary study
1Department of Diagnostic Radiology, University Hospital, Uppsala, Sweden.
Insights
Branching geometry in cerebral arteries with aneurysms increases shear stress (SS) and SS gradients. This finding may indicate altered vessel regulation in patients with intracranial saccular aneurysm.
Area of Science:
- Neuroscience
- Biomedical Engineering
- Cardiovascular Research
Background:
- Intracranial saccular aneurysms are often associated with hemodynamic forces.
- Shear stress (SS) on vessel walls is a key factor in aneurysm etiology.
- Aneurysms occur in both major and peripheral cerebral arteries.
Purpose of the Study:
- To determine if branching geometry increases shear stress (SS) in cerebral arteries of patients with aneurysms.
- To investigate SS in arteries distal to the circle of Willis.
Main Methods:
- Estimated the ratio of SS in branches to the parent vessel at bifurcations using vessel caliber relations.
- Calculated SS gradients at bifurcation apices.
- Analyzed cerebral angiograms from 10 patients with distal anterior cerebral artery aneurysms and compared to normal values.
Main Results:
- Branching geometry significantly increases SS in arterial branches.
- A notable increase in SS gradients at bifurcation apices was observed in patients with aneurysms.
Conclusions:
- The observed increase in SS may be linked to elevated cerebral vessel tone post-subarachnoid hemorrhage.
- Alternatively, it could suggest a regulatory disorder of cerebral arterial caliber and SS in aneurysm patients.
Purpose:
To investigate whether the branching geometry determines an underlying increase of shear stress (SS) on the vessel wall in cerebral arteries of patients with aneurysms located distally to the circle of Willis. Increased SS is regarded as a major factor in the etiology of intracranial saccular aneurysm. Aneurysms occur commonly in the Willisian arteries, where the role of hemodynamic forces are evident, but they occur also in more peripheral arteries.
Material And Methods:
The ratio between SS in the branches and SS in the parent vessel at bifurcations was estimated using exponential relations of vessel caliber. The absolute difference of SS branch ratios in every bifurcation represents the SS gradient at the apex. Cerebral angiograms of 10 patients with aneurysm of the distal anterior cerebral artery were analyzed and compared with normal values from an earlier study.
Results:
The branching geometry determines a relatively small but significant increase of SS in branches and of SS gradients at bifurcation apices in cerebral arteries of patients with aneurysm.
Conclusion:
The results may reflect increased cerebral vessel tone after subarachnoidal hemorrhage, or alternatively an underlying derangement of the regulation of cerebral arterial caliber and SS in these patients.