Compensatory patterns of collateral flow in stroke patients with unilateral and bilateral carotid stenosis

Abstract

BackgroundCollateral pathways are important in maintaining adequate cerebral blood flow in patients with carotid stenosis. We aimed to evaluate the hemodynamic patterns in relation to carotid stenosis in acute stroke patients.MethodsConsecutive 586 stroke patients in a hospital based cohort were included in the present study. Carotid duplex was performed to identify patients with absolute minimal diameter reductions of 50 % or greater in their internal carotid arteries (ICAs). Color velocity imaging quantification ultrasound (CVIQ) was used to measure extracranial arterial blood flow volume (BFV) in bilateral common carotid arteries (CCAs) and bilateral vertebral arteries (VAs). The absolute values of BFV and the ratios were compared between patients with and without ICA stenosis.ResultsAmong 586 acute ischemic stroke patients (mean age: 67.5 ± 12.4y), ICA stenosis was detected in 112 patients (19.1 %), including unilateral ICA stenosis in 81 patients (13.8 %) and bilateral ICA stenosis in 31 patients (5.3 %). Among patients with unilateral ICA stenosis, the BFV in contralateral CCA was significantly higher than that in ipsilateral CCA (325.5 ± 99.8 mL/min vs. 242.2 ± 112.2 mL/min, P < 0.001). Among patients with bilateral ICA stenosis, the sum of BFV in bilateral VAs accounted for 22 % of the whole cerebral blood flow, which was significantly higher than that in those without ICA stenosis (14.8 %, P < 0.001) or with unilateral ICA stenosis (16.9 %, P = 0.007).ConclusionsIn patients with unilateral carotid stenosis, contralateral carotid blood flow increases to compensate decreased blood flow, while posterior circulation may compensate for the decreased brain perfusion in those with bilateral carotid stenosis.

Cerebrovascular reactivity recovery following carotid angioplasty and stenting

“…Cerebrovascular reactivity improved, as well, on the contralateral side despite being within normal range before stenting. It can be explained by the active contribution of the contralateral carotid system in collateral supply through an increase in its flow volume [18]. This finding points to a hemodynamic stress on the contralateral side also that is corrected following revascularization.…”

Automatic flow analysis of digital subtraction angiography using independent component analysis in patients with carotid stenosis

“…Cerebral perfusion has been reported to be influenced by multiple factors such as proximal luminal stenosis, collateral circulation, and brain parenchyma viability [ 29 , 30 ]. Therefore, the carotid degree of stenosis alone could not approximate cerebral perfusion deficits.…”

Incomplete circle of Willis and cerebrovascular reactivity in asymptomatic patients before and after carotid endarterectomy

“…In asymptomatic patients with significant carotid artery stenosis reduced cerebrovascular reactivity increases risk of stroke 13-25% per year [7][8][9][10][11]. Decreased circulatory reserve and lack of collateralization may increase the risk of stroke by the mechanism of impaired hemodynamics and due to the fact that arterio-arterial embolization from diseased carotid artery occurs more often in the zone of reduced circulatory reserve [12,13].…”

“…Circle of Willis (CoW) provides the most significant collateral flow in the presence of significant stenosis or occlusion of internal carotid artery (ICA). Anterior collateral segment of CoW (ACA1, AcomA) is a connection between opposite carotid arteries and posterior collateral segment (ACP1, AcomP) provides collateral from posterior cerebral circulation [1].…”