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Updated: May 24, 2026
08:42
Ultrasound Assessment of Endothelial-Dependent Flow-Mediated Vasodilation of the Brachial Artery in Clinical Research
Published on: October 22, 2014
Velocity acceleration as a determinant of flow-mediated dilation
1School of Sport and Exercise, Massey University, Wellington, New Zealand. L.Stoner@massey.ac.nz
Ultrasound in Medicine & Biology
|February 21, 2012
Summary
Velocity acceleration, not just mean blood velocity, significantly impacts flow-mediated dilation (FMD). Accounting for acceleration reveals FMD is not significantly different between conditions, suggesting mean velocity alone is insufficient to characterize shear stress.
Area of Science:
- Physiology
- Cardiovascular Research
- Biomedical Engineering
Background:
- Flow-mediated dilation (FMD) is a key indicator of vascular health.
- Shear stress, primarily estimated by mean blood velocity, is the established stimulus for FMD.
- Pulsatile blood flow introduces velocity acceleration, potentially influencing the shear stimulus.
Purpose of the Study:
- To investigate the role of velocity acceleration in FMD.
- To determine if velocity acceleration is a critical factor in characterizing shear stress for FMD.
- To assess the impact of increased velocity acceleration on FMD measurements.
Main Methods:
- Defined FMD as the brachial artery shear rate-diameter slope.
- Recruited 14 healthy, young, physically active males.
- Induced controlled increases in velocity acceleration using a forearm tourniquet (40 mm Hg).
- Utilized hierarchical linear modeling to analyze shear stress and diameter changes.
- Measured FMD before and after inducing velocity acceleration.
Main Results:
- A 40 mm Hg tourniquet increased velocity acceleration by 14% (p=0.001).
- FMD was initially attenuated by 11.0% (p=0.015) in the acceleration condition.
- After including velocity acceleration as a covariate, FMD differences between conditions became non-significant (p=0.619).
Conclusions:
- Mean blood velocity alone may inadequately represent the shear stress stimulus for FMD.
- Velocity acceleration is an important component of the shear stimulus that influences FMD.
- Future studies should consider velocity acceleration for a more accurate assessment of FMD.
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