Conduit Artery Constriction Mediated by Low Flow: A Novel Noninvasive Method for the Assessment of Vascular Function Original Research Article

Conduit Artery Constriction Mediated by Low Flow: A Novel Noninvasive Method for the Assessment of Vascular Function Original Research Article Pages 1953-1958 Tommaso Gori, Saverio Dragoni, Monica Lisi, Giuseppe Di Stolfo, Serena Sonnati, Massimo Fineschi, John D. Parker Close Close preview | PDF (1123 K) | Related articles | Related reference work articles AbstractAbstract | Figures/TablesFigures/Tables | ReferencesReferences 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. Article Outline Methods Population Measurement of arterial diameter, L-FMC, and FMD Mechanistic studies The Role of Nitric Oxide (NO) The Effect of Fluconazole and Aspirin The Role of Blood Pressure Changes and Distending Pressure The Role of Systemic Reflexes Statistical analysis Results Reproducibility of L-FMC and FMD Repeatability of L-FMC and FMD Mechanistic studies The Role of NO The Role of EDHF and Cyclooxygenase Products The Role of Blood Pressure Changes L-FMC in health and disease Discussion Conclusions References