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This Article Full Text Full Text (PDF) All Versions of this Article: 295/4/H1594    most recent 00669.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Thijssen, D. H. J. Articles by Green, D. J. Search for Related Content PubMed PubMed Citation Articles by Thijssen, D. H. J. Articles by Green, D. J.

The impact of baseline diameter on flow-mediated dilation differs in young and older humans

¹Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, United Kingdom; ²Department of Physiology, Radboud University Nijmegen Medical Centre, The Netherlands; and ³School of Sport Science, Exercise and Health, The University of Western Australia, Crawley, Western Australia

Submitted 25 June 2008 ; accepted in final form 8 August 2008

Flow-mediated dilation (FMD) has become a commonly applied approach for the assessment of vascular function and health, but methods used to calculate FMD differ between studies. For example, the baseline diameter used as a benchmark is sometimes assessed before cuff inflation, whereas others use the diameter during cuff inflation. Therefore, we compared the brachial artery diameter before and during cuff inflation and calculated the resulting FMD in healthy children (n = 45; 10 ± 1 yr), adults (n = 31; 28 ± 6 yr), and older subjects (n = 22; 58 ± 5 yr). Brachial artery FMD was examined after 5 min of distal ischemia. Diameter was determined from either 30 s before cuff inflation or from the last 30 s during cuff inflation. Edge detection and wall tracking of high resolution B-mode arterial ultrasound images was used to calculate conduit artery diameter. Brachial artery diameter during cuff inflation was significantly larger than before inflation in children (P = 0.02) and adults (P < 0.001) but not in older subjects (P = 0.59). Accordingly, FMD values significantly differed in children (11.2 ± 5.1% vs. 9.4 ± 5.2%; P = 0.02) and adults (7.3 ± 3.2% vs. 4.6 ± 3.3%; P < 0.001) but not in older subjects (6.3 ± 3.4% vs. 6.0 ± 4.2%; P = 0.77). When the diameter before cuff inflation was used, an age-dependent decline was evident in FMD, whereas FMD calculated using the diameter during inflation was associated with higher FMD values in older than younger adults. In summary, the inflation of the cuff significantly increases brachial artery diameter, which results in a lower FMD response. This effect was found to be age dependent, which emphasizes the importance of using appropriate methodology to calculate the FMD.

methodology

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