Bone and Joint Institute
Heterogeneous patterns of vasoreactivity in the middle cerebral and internal carotid arteries
Document Type
Article
Publication Date
1-1-2015
Journal
American Journal of Physiology - Heart and Circulatory Physiology
Volume
308
Issue
9
First Page
H1030
Last Page
H1038
URL with Digital Object Identifier
10.1152/ajpheart.00761.2014
Abstract
© 2015 the American Physiological Society. This study compared changes in cross-sectional area (CSA) and flow (Q) between the middle cerebral artery (MCA) and the internal carotidartery (ICA) at baseline and during 5 min of hypercapnia (HC; 6% CO2) and hypocapnia (HO; hyperventilation) and quantified how these changes contribute to estimates of cerebrovascular reactivity (CVR). Measures of MCA CSA were made using 3T magnetic resonance imaging. On a separate day, MCA flow velocity was measured with transcranial Doppler ultrasound and ICA diameters and flow velocity were measured with duplex ultrasound. Fourteen subjects (23 ± 3 yr, 7 females) participated, providing data for 11 subjects during HC and 9 subjects during HO. An increase in MCA CSA (P < 0.05) was observed within the first minute of HC. During HO, the decrease in MCA CSA (P < 0.05) was delayed until minute 4. No changes were observed in ICA CSA during HC or HO. The relative changes in QICA and QMCA were similar during HC and HO. Therefore, the MCA, but not ICA, dilates and constricts during 5 min of HC and HO, respectively. The consequent impact on QMCA significantly affects estimates of CVR, and reactivity cannot be attributed solely to changes in smaller arterioles.
Notes
Article is freely available from the publisher