Carotid Blood Flow Assessment during Dynamic Respiratory Maneuvers Demonstrates a Shift toward Vasoconstriction with...

Area of Science:

• Vascular Physiology
• Neuroimaging
• Cardiovascular Research

Background:

• Internal carotid artery (ICA) blood flow offers a potential alternative for measuring cerebrovascular reactivity (CVR).
• Endothelium-dependent vasodilatory dysfunction is a key area of investigation.
• Assessing CVR in the ICA during routine carotid investigations is explored.

Purpose of the Study:

• To investigate the feasibility of testing CVR in the ICA during routine clinical carotid investigations.
• To evaluate CVR using breath-hold (BH) and rapid-breathing (RB) challenges.
• To determine the validity of ICA CVR assessment through data quality, inter-challenge agreement, and age association.

Main Methods:

• CVR assessed via BH and RB effects on ICA diameter, blood velocities (PSV, EDV, MV), and volume flow.
• Measurements correlated with end-tidal CO2 (etCO2) changes.
• Feasibility and validity determined by recording quality, challenge agreement, and age correlation.

Main Results:

• High-quality recordings (96% for rest, 90% for BH, 88% for RB) were achieved in 50 patients (68 ± 13 years).
• Age-related reductions in ICA blood velocities were observed at rest and during BH and RB.
• Differential age associations were noted between BH (hypocapnic) and RB (hypercapnic) stimuli, suggesting varying vasoconstriction tendencies.

Conclusions:

• Assessing CVR in the ICA during routine carotid duplex is feasible, practical, and yields high-quality data.
• The study highlights differential age-related responses to hypercapnic and hypocapnic stimuli.
• Findings suggest a greater tendency towards vasoconstriction in older individuals.