title: Measurement of flow-mediated dilatation of the brachial artery is affected by local elastic vessel wall properties in high-risk patients.
abstract: OBJECTIVE
  To assess whether the validity of endothelial function measurement by flow-mediated dilatation (FMD) is affected by local brachial artery stiffness (distensibility coefficient; DC) and arterial wall thickness (intima-media thickness, IMT).
  
  
  BACKGROUND
  FMD measurement relies on assessment of arterial diameter change. Increased IMT and decreased DC might physically limit dilatation of the brachial artery in spite of healthy endothelium.
  
  
  METHODS
  DC, IMT and FMD of the brachial artery were simultaneously measured in 349 patients with advanced atherosclerosis or cardiovascular risk factors. The relations between FMD and age, and FMD and current smoking were regarded as a proxy for the relation between FMD and true endothelial function.
  
  
  RESULTS
  The relations between FMD and age, and FMD and smoking, were significantly modified by brachial artery DC. No modification was found for IMT. The interaction terms were statistically significant (p=0.03 and 0.04, respectively). The relation between FMD and age, and FMD and smoking was progressively more pronounced in patients with more elastic arteries.
  
  
  CONCLUSIONS
  The results of our study indicate that increased arterial stiffness may interfere with valid measurement of FMD and that patients with stiff arteries may be considered for exclusion from analyses involving FMD to ensure its validity.
authors.affiliation: Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Str 6.131, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Witte
authors.forename: Yolanda
authors.initials: Y
authors.lastname: van der Graaf
authors.forename: Diederick E
authors.initials: DE
authors.lastname: Grobbee
authors.forename: Michiel L
authors.initials: ML
authors.lastname: Bots
mesh_terms: D000328:Adult; D000368:Aged; D050197:Atherosclerosis / Q000453:epidemiology / Q000473:pathology* / Q000503:physiopathology*; D001916:Brachial Artery / Q000473:pathology / Q000502:physiology*; D003935:Diagnostic Techniques, Cardiovascular / Q000592:standards*; D004548:Elasticity; D004730:Endothelium, Vascular / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012039:Regional Blood Flow / Q000502:physiology; D015203:Reproducibility of Results; D012307:Risk Factors; D014664:Vasodilation / Q000502:physiology*