P6.07 METHODOLOGICAL ASPECT OF BRACHIAL FLOW MEDIATED DILATION: IMPROVEMENT OF REPRODUCIBILITY

Abstract

Brachial artery flow-mediated dilation (FMD) is the most widely used technique for assessing endothelial function in humans. FMD is reduced in the presence of cardiovascular risk factors and diseases and it is an independent predictor of events. However, its major limitation is the relatively low reproducibility. One of the main challenge is to maintain a stable scan plane during examinations, especially when the forearm cuff is inflated/deflated. The aim of this study was to evaluate the FMD reproducibility when resting diameter is calculated as the mean value measured from 8th to 9th minute after reactive hyperemia, when the vasodilation is concluded (BAS_POST), and to compare the results with those obtained with a standard assessment of resting diameter over 1minute before cuff inflation (BAS_PRE). Thirty healthy subjects (age 25–45 years) underwent two FMD examinations 30minutes apart. FMD to 5minutes forearm ischemia was assessed by one trained operator using a clamp to hold the ultrasound probe in the same position and calculated as maximum percentage increase in diameter with respect to BAS_PRE and BAS_POST, by a real-time automatic edge-detection system (FMD Studio, Institute of Clinical Physiology, Pisa, Italy). FMD% variability was assessed as intra-session coefficients of variation (CV). Diameter was 3.56+0.66mm in BAS_PRE and 3.57+0.66mm in the BAS_POST. FMD% was 7.4+3.8% with BAS_PRE and 7.1+3.7% with BAS_POST. CV of FMD% was 15.61+10.9% in BAS PRE and 9.22+5.93% with BAS_POST calculation. These results suggest that FMD% calculated with BAS_POST can ensure a more reproducible measure of conduit artery endothelial function.