Comparison of ultrasound assessment of flow-mediated dilatation in the radial and brachial artery with upper and forearm cuff positions

In the published literature relating to flow-mediated dilatation (FMD), the re are substantial differences between centres in terms of normal FMD among st healthy subjects. This present study attempts to identify the effect of differing methodologies on FMD. High frequency ultrasound was used to measu re blood flow and percentage brachial and radial artery dilatation after re active hyperaemia induced by forearm or upper arm cuff occlusion in 24 heal thy subjects, less than 40 years, without known cardiovascular risk factors . FMD of the brachial artery was significantly higher after upper arm occlu sion, compared with forearm occlusion, 6.4 (3.3) and 3.9 (2.6)% (P <0.05), respectively. FMD of the radial artery was significantly higher after forea rm occlusion, compared with upper arm occlusion, 10.0 (4.6) and 7.9 (3.5)% (P <0.05), respectively. The percentage blood flow increase in the brachial and radial arteries after forearm and upper arm occlusion were similar. Af ter forearm and upper arm occlusion, the radial artery percentage dilatatio n was greater than the brachial artery. In conclusion dilatation of the bra chial artery, after reactive hyperaemia induced by upper arm occlusion, was significantly more pronounced compared with dilatation of the brachial art ery after forearm occlusion, despite a similar percentage blood flow increa se. The local ischaemia of the brachial artery with a proximal occlusion ma y explain why the brachial artery dilated more after upper arm occlusion co mpared with after forearm occlusion. The study has also shown that FMD of t he radial artery could be assessed by B-mode ultrasound technique. FMD was greater using the radial artery compared with the brachial artery, suggesti ng that the radial artery may be a useful way to assess FMD in future clini cal studies.