The Circle of Willis (CoW) is the most effective collateral
circulation to the brain during internal carotid artery (ICA) occlusion.
Carotid stump pressure (CSP) is an established surrogate measure of the
cerebral collateral circulation. This study aims to use hemodynamic and
computed tomography angiography measurements to determine the strongest
influences upon the dependent variable, CSP. These findings could help
clinicians noninvasively assess the adequacy of the collateral circulation
and facilitate surgical risk assessment in an outpatient setting.
CSP and mean arterial pressure were measured during carotid
endarterectomy or during carotid balloon test occlusion in 92 patients.
Intracranial arterial diameters were measured on computed tomography
angiography at 16 different locations. Univariate and multivariate analyses
were used to determine the key factors associated with CSP. In a subgroup of
individuals (n=27) with severe (>70% North American Symptomatic Carotid
Endarterectomy Trial) contralateral stenosis or occlusion, the same analysis
The contralateral anterior cerebral artery proximal to anterior
communicating artery (A1) of the CoW had the strongest influence upon CSP,
followed by the mean arterial pressure, the contralateral ICA diameter, and
the anterior communicating artery diameter (R
2=0.364). In the subgroup with high-grade contralateral ICA
stenosis, the ipsilateral posterior communicating artery exerted the
strongest influence (R
During ICA occlusion, the anterior CoW dominates in preserving
collateral flow, especially the contralateral A1 segment. In individuals
with high-grade contralateral carotid stenosis, the posterior communicating
artery calibre becomes a dominant influence. The most favourable anatomy
consists of large contralateral A1 and anterior communicating arteries, and
no contralateral carotid stenosis.