New Methodological Approach to Improve Reproducibility of Brachial Artery Flow-mediated Dilatation

Background: Measurement of flow-mediated dilation (FMD) is well known as a noninvasive method for an assessment of vascular endothelial function. However, the reproducibility is a major issue of FMD measurement. The purpose of this study is to examine the reproducibility of the new FMD measurement with medial epicondyle method.

Methods: First, to evaluate the variability of the brachial artery diameter, 23 volunteers recruited from 32 healthy volunteers were examined for a brachial artery diameter at rest using with FMD equipment. Second, to evaluate the reproducibility of the FMD measurement, all volunteers underwent the FMD measurement, which was repeated at 2-week interval using the traditional method and the medial epicondyle method. The reproducibility in both methods was evaluated by 2 independent observers who measured on the same subject to assess the inter-observer reproducibility, and 1 observer who measured the same subject twice to assess the intra-observer reproducibility regarding the baseline value of arterial diameter and FMD.

Results: The variability of brachial artery diameter was 0.57 ± 0.27 mm in 23 healthy volunteers. In the study of inter- and intra-observer reproducibility, 2 parameters including intra-class correlation coefficient and Pearson's correlation coefficient by medial epicondyle method are superior to those by traditional method.

Conclusions: These results suggest that medial epicondyle methodological approach to measure FMD is superior to traditional method.