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Updated: Jul 5, 2026
A Methodological Approach to Non-invasive Assessments of Vascular Function and Morphology
Published on: February 7, 2015
Conduit artery constriction mediated by low flow a novel noninvasive method for the assessment of vascular function
Tommaso Gori1, Saverio Dragoni, Monica Lisi
1Department of Internal, Cardiovascular and Geriatric Medicine, University of Siena, Siena, Italy. Tommaso.gori@utoronto.ca
Insights
A new noninvasive method, low-flow-mediated constriction (L-FMC), complements traditional flow-mediated dilation (FMD) by measuring resting arterial tone. This accurate technique provides additional vascular reactivity insights, aiding cardiovascular disease assessment.
Area of Science:
- Vascular biology and cardiovascular research
- Noninvasive diagnostic techniques
- Arterial reactivity assessment
Background:
- Peripheral vascular reactivity is crucial for diagnosing and predicting cardiovascular disease risk.
- Traditional flow-mediated dilation (FMD) assesses endothelial function but has limitations.
- Novel methods are needed to complement existing vascular reactivity assessments.
Purpose of the Study:
- To describe and validate a novel noninvasive method, low-flow-mediated constriction (L-FMC), that complements traditional FMD.
- To assess the repeatability and diagnostic utility of L-FMC and FMD.
- To investigate the impact of various physiological and pharmacological interventions on L-FMC and FMD.
Main Methods:
- High-resolution ultrasound and automated analysis measured radial artery diameter under varying shear stress conditions (L-FMC and FMD).
- Repeatability was assessed, and a composite endpoint (L-FMC + FMD) was calculated.
- 196 studies were performed, including assessments after smoking, in patient cohorts, and following pharmacological interventions.
Main Results:
- The L-FMC and FMD methods demonstrated good repeatability (intraclass correlation coefficients 0.80 and 0.68, respectively).
- Both L-FMC and FMD were significantly blunted in smokers, coronary artery disease patients, and hypertensive patients compared to controls.
- Specific pharmacological agents differentially affected L-FMC and FMD, highlighting distinct underlying mechanisms.
Conclusions:
- Low-flow-mediated constriction (L-FMC) is a simple, rapid, and accurate measure of resting arterial tone.
- L-FMC provides complementary information to FMD by assessing responses to resting shear stress.
- This novel method enhances the noninvasive evaluation of peripheral vascular reactivity.
Objectives:
We describe and validate a novel noninvasive method that complements the data from "traditional" flow-mediated dilation (FMD) studies.
Background:
The study of peripheral vascular reactivity provides important diagnostic and prognostic information in patients with (or at risk for) cardiovascular disease.
Methods:
High-resolution ultrasound and automatic computerized analysis were used to measure the diameter of the radial artery at rest and in conditions of locally decreased and increased shear stress (respectively, low-flow-mediated constriction [L-FMC] and flow-mediated dilation [FMD]). A composite end point (L-FMC + FMD) was also calculated. A total of 196 studies were performed.
Results:
When the repeatability of the method was tested, the range of variation across measurements was 1.1% for L-FMC and 1.7% for FMD; the intraclass correlation coefficient was 0.80 and 0.68, respectively. Low-flow-mediated constriction, FMD, and their composite end point were significantly blunted after acute smoking, in coronary artery disease patients, and in hypertensive patients as compared with that seen in healthy age-matched volunteers (p < 0.01, analysis of variance). Low-flow-mediated constriction, but not FMD, was blunted (p < 0.05) after administration of fluconazole (an inhibitor of a cytochrome P450-derived endothelium-derived hyperpolarization factor) and aspirin (an inhibitor of cyclooxygenase). Flow-mediated dilation, but not L-FMC, was blunted (p < 0.05) by nitric oxide synthase inhibition.
Conclusions:
Low-flow-mediated constriction is a simple, rapid, and accurate measure of resting arterial tone that does not require further procedures as compared with "traditional" FMD measurements. While FMD measures endothelial responses to sudden increases in shear stress, L-FMC is a measure of the response to resting shear stress levels, and, therefore, it provides additional information that is complementary to FMD.
