The Moens-Korteweg equation predicts changes in pulse wave velocity (PWV) following changes in arterial radius, therefore an increase in arterial radius, as seen in a reactive hyperaemia (RH) condition, should slow PWV over a given arterial segment. If this assumption is true, than the deceleration of PWV over the brachial artery (flow-mediated slowing – FMS) should be an equivalent signal of endothelial function during a conventional RH flow-mediated dilation (FMD) procedure. Our aim was to compare FMS with FMD after RH in healthy subjects, as part of a study that seeks to evaluate the clinical usefulness of FMS.Objective:
Figure 1. Correlation of FMS and FMD.Design and method:
Cross-sectional study including 25 healthy participants (72% females), mean age 21.12 ± 0.73 years. FMD and FMS were simultaneously measured at baseline and 1 min after a ischemia period. Ischemia was induced by inflating a cuff for 5 min on the right forearm, 50mmHg above each participant's systolic blood pressure. FMS was measured as the absolute (δ) and percentual (%) change in carotid-radial PWV (PWV), measured with the Complior Analyse.Results:
Mean baseline brachial diameter was 3.46 ± 0,59 mm, and was smaller in females compared with males (3.12 ± 0,22 mm versus 4.17 ± 0,43 mm, respectively; p < 0.001). Mean FMD was 8.18 ± 3.65%, δPWV was −0.83 ± 0.70 m/s, and % PWV was 9.45 ± 8.31%, and were similar in males and females. A significant correlation was observed between both measures of FMS (δPWV and % PWV) and echo FMD: R = −0,42 (p = 0,04) and R = 0,46 (p = 0,02), respectively (cf. figure). FMS was shown to be dependent on the baseline brachial diameter, with smaller variations depicted for smaller baseline brachial diameters.Conclusions:
FMS measured with the Complior Analyse device appears to be a promising and feasible method for measuring changes following RH, showing a significant correlation with FMD in young and healthy individuals, although further studies are needed to demonstrate the clinical usefulness of this method.