Circle of Willis Collateral During Temporary Internal Carotid Artery Occlusion I: Observations From Digital Subtraction Angiography
Abstract Introduction: Impaired collateral circulation can lead to stroke during carotid endarterectomy. Carotid stump pressure (CSP) is used as a surrogate measure of collateral flow. The objective was to determine whether anatomical features obtained from digital subtraction angiography correlate with CSP during temporary internal carotid artery occlusion. The second objective was to use these features in combination to predict CSP. Methods: Digital subtraction angiographies from 102 patients obtained before endarterectomy were reviewed for anatomical variables including: degree of ipsilateral and contralateral carotid artery stenosis; patency of the anterior communicating artery; presence of cross flow into ipsilateral middle cerebral artery branches; and size or =1 mm calibre) of the ipsilateral proximal anterior cerebral (A1) the contralateral A1, and the ipsilateral posterior communicating arteries. At surgery, systemic mean arterial pressure (MAP) and CSP were recorded. Multiple regression analysis was used to assess for anatomical features significantly associated with CSP. A "predicted CSP" equation was applied to 54 subsequent patients and correlated with measured CSP. Results: Variables correlating with CSP included MAP (p=0.001) the presence of severe contralateral carotid stenosis (p=0.002) patency of the anterior communicating artery (p=0.013) and the size of the contralateral A1 segment (p=0.029) Angiographic cross flow, ipsilateral A1 size, and ipsilateral posterior communicating artery size were not significant. Predicted CSP correlated significantly with measured CSP (p<0.0001; R 2=0.34) Conclusions: Anatomical features and systemic MAP are associated with carotid stump pressure during internal carotid artery occlusion and account for a significant amount of its variation. RESUME Circulation collaterale dans le cercle arteriel de Willis pendant une occlusion temporaire de la carotide interne. 1 observations a l'angiographie numerique. Contexte: Pendant une endarterectomie carotidienne, une alteration de la circulation collaterale peut donner lieu a un accident vasculaire cerebral. La pression dans le moignon carotidien (PMC) est utilisee comme mesure substitutive du flux collateral. Le but de cette etude etait de determiner si les caracteristiques anatomiques obtenues a l'angiographie numerique correspondent a la PMC pendant une occlusion temporaire de la carotide interne. Le deuxieme objectif etait d'utiliser une combinaison de ces caracteristiques pour predire la PMC. Methodologie: Nous avons revu l'angiographie numerique obtenue chez 102 patients avant l'endarterectomie pour documenter les variables anatomiques dont le degre de stenose homolateral et controlateral de la carotide, la permeabilite de la communicante anterieure, la presence de flux transversal dans les branches de l'artere cerebrale moyenne homolaterale et la taille (calibre ou 1mm) de l'artere cerebrale anterieure proximale homolaterale (A1) de l'A1 controlaterale et des arteres communicantes posterieures homolaterales. Au moment de la chirurgie, la pression arterielle moyenne systemique (PAM) et la PMC ont ete enregistrees. L'analyse de regression multiple a ete utilisee pour identifier les caracteristiques anatomiques associees de facon significative a la PMC. La PAM predite a ete calculee prospectivement au moyen d'une equation chez 54 patients consecutifs et correlee a la PMC mesuree. Resultats: Les variables correlees a la PMC etaient les suivantes la PAM (p=0,001) la presence d'une stenose carotidienne controlaterale severe (p=0,002) la permeabilite de l'artere communicante anterieure (p=0,013) et la taille du segment A1 controlateral (p=0,029) Le flux angiographique transversal, la taille de l'A1 homolaterale et la taille de l'artere communicante posterieure homolaterale n'etaient pas des variables significatives au point de vue statistique. La PMC predite etait correlee de facon significative a la PMC mesuree (p<0,0001 R2=0,34) Conclusions: Les caracteristiques anatomiques et la PAM systemique sont associees a la pression dans le moignon carotidien pendant l'occlusion de la carotide interne et expliquent une grande partie de sa variation.
Canadian Journal of Neurological Sciences Journal Canadien des Sciences Neurologiques