Adjusting flow-mediated dilation for shear stress stimulus allows demonstration of endothelial dysfunction in a population with moderate cardiovascular risk

J Vasc Res. 2009;46(6):592-600. doi: 10.1159/000226227. Epub 2009 Jun 30.


Background/aims: Although normalization of brachial artery flow-mediated dilation (FMD) to individual shear stress (FMD:shear stress ratio) has been proposed to improve this measure of endothelial function, the clinical utility of FMD normalization has not yet been demonstrated. We tested (1) whether following conventional 5-min forearm occlusion, the FMD:shear stress ratio would discriminate a population with moderate cardiovascular risk (MR) from a low-risk (LR) population, and (2) whether the dose-response profile relating shear stress to FMD would be different between the 2 populations.

Methods: Five different magnitudes of reactive hyperemia-induced shear stress were applied to 20 MR and 20 LR subjects by manipulating forearm cuff occlusion duration. Brachial artery diameters and velocities were measured via high-resolution ultrasound. To quantify the hyperemic stimulus, shear stress area under the curve was individually calculated for the duration of time-to-peak dilation.

Results: Following 5-min of forearm occlusion, FMD:shear stress ratio (p = 0.041), but not FMD (p = 0.286), discriminated MR from LR. The slope of the shear stress-FMD regression line was lower in MR compared to the LR (p < 0.001).

Conclusion: The FMD:shear stress ratio distinguished reduced endothelial function in a population with MR. The dose-response profile of the shear stress-FMD relationship appears to differ between populations of distinct cardiovascular risk.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Blood Flow Velocity
  • Brachial Artery / diagnostic imaging
  • Brachial Artery / physiopathology*
  • Cardiovascular Diseases / diagnostic imaging
  • Cardiovascular Diseases / etiology*
  • Cardiovascular Diseases / physiopathology
  • Endothelium, Vascular / diagnostic imaging
  • Endothelium, Vascular / physiopathology*
  • Female
  • Forearm / blood supply*
  • Humans
  • Hyperemia
  • Laser-Doppler Flowmetry
  • Linear Models
  • Male
  • Middle Aged
  • Regional Blood Flow
  • Risk Assessment
  • Risk Factors
  • Stress, Mechanical
  • Time Factors
  • Ultrasonography
  • Vasodilation*