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Heterogeneity in conduit artery function in humans: impact of arterial size
Dick H J Thijssen1, Ellen A Dawson, Mark A Black
1Research Institute for Sport and Exercise Science, Liverpool John Moore's University, Henry Cotton Campus, 15-21 Webster St., Liverpool L3 2ET, United Kingdom. d.thijssen@fysiol.umcn.nl
Insights
Artery size impacts vascular function. Smaller conduit arteries show greater flow-mediated dilation (FMD) and glyceryl trinitrate (GTN)-mediated responses, suggesting size influences vascular health. This study highlights artery size as a key factor in functional responses.
Area of Science:
- Cardiovascular Physiology
- Vascular Biology
- Biomedical Engineering
Background:
- Conduit artery size is a potential determinant of vascular function.
- Understanding this relationship is crucial for assessing cardiovascular health and disease.
- Previous research has not fully elucidated the impact of artery size on functional responses.
Purpose of the Study:
- To investigate the relationship between conduit artery size and functional vascular responses.
- To compare flow-mediated dilation (FMD) and glyceryl trinitrate (GTN)-mediated responses across different artery sizes.
- To determine if artery size influences the shear rate stimulus for FMD.
Main Methods:
- Simultaneous assessment of FMD and GTN responses in upper and lower limb arteries using high-resolution ultrasound.
- Continuous calculation of artery diameter, blood flow, and shear rate.
- Analysis of the correlation between baseline artery size and vascular function metrics.
Main Results:
- Baseline artery size inversely correlated with FMD response (r = -0.57, P < 0.001).
- Smaller arteries (radial, brachial, popliteal) exhibited significantly greater FMD% and GTN responses.
- The relationship between artery size and function persisted even after normalizing for shear rate.
Conclusions:
- Systematic differences exist in the vascular function of conduit arteries based on their size.
- Artery size is an independent factor influencing vascular responses, not solely explained by shear rate.
- These findings suggest that individual differences in artery size may significantly impact vascular health and functional capacity.
Abstract:
To determine whether conduit artery size affects functional responses, we compared the magnitude, time course, and eliciting shear rate stimulus for flow-mediated dilation (FMD) in healthy men (n = 20; 31 +/- 7 yr). Upper limb (brachial and radial) and lower limb (common and superficial femoral) FMD responses were simultaneously assessed, whereas popliteal responses were measured in the same subjects during a separate visit. Glyceryl trinitrate (GTN)-mediated responses were similarly examined. Edge detection and wall tracking of high-resolution B-mode arterial ultrasound images, combined with synchronized Doppler waveform envelope analysis, were used to calculate conduit artery diameter, blood flow, and shear rate continuously across the cardiac cycle. Baseline artery size correlated inversely with the FMD response (r = -0.57, P < 0.001). Within-artery comparisons revealed a significant inverse correlation between artery size and FMD% for the radial (r = -0.66, P = 0.001), brachial (r = -0.55, P = 0.01), and popliteal artery (r = -0.48, P = 0.03), but not for the superficial and common femoral artery. Normalization of FMD responses for differences in eliciting shear rate did not abolish the between-artery relationship for artery function and size (r = -0.48, P < 0.001), suggesting that differences between artery function responses were not entirely due to size-related differences in shear rate. This was reinforced by a significant between-artery correlation for GTN responses and baseline artery size (r = -0.74, P < 0.001). In summary, systematic differences exist in vascular function responses of conduit arteries that differ in size. This raises the possibility that differences in artery size within or between individuals may influence functional responses.
