Endothelium function dependence of acute changes in pulse wave velocity and flow-mediated slowing

Flow-mediated slowing (FMS), defined as the minimum pulse wave velocity (PWV_min) during reactive hyperemia, is potentially a simple, user-objective test for examining endothelial function. The purpose of the current study was to determine the effects of a known endothelial dysfunction protocol on arm PWV and PWV_min. Complete data were successfully collected in 22 out of 23 healthy adults (23.8 years [SD 4.1], 16 F, 22.8 kg/m² [SD 2.8]). Local endothelial dysfunction was induced by increasing retrograde shear stress in the upper arm, through inflation of a distal (forearm) tourniquet to 75 mmHg, for 30 min. Pre- and post-endothelial dysfunction, PWV was measured followed by simultaneous assessment of PWV_min and flow-mediated dilation (FMD). PWV was measured between the upper arm and wrist using an oscillometric device, and brachial FMD using ultrasound. FMD (%) and PWV_min (m/s) were calculated as the maximum increase in diameter and minimum PWV during reactive hyperemia, respectively. Endothelial dysfunction resulted in a large effect size (ES) decrease in FMD (∆ = -3.10%; 95% CI: -4.15, -2.05; ES = -1.3), and a moderate increase in PWV (∆ = 0.38 m/s; 95% CI: 0.07, 0.69; ES = 0.5) and PWV_min (∆ = 0.16 m/s; 95% CI: 0.05, 0.28; ES = 0.6). There was a large intra-individual (pre- vs post-endothelial dysfunction) association between FMD and PWV_min (r = -0.61; 95% CI: -0.82, -0.24). In conclusion, acute change in PWV and PWV_min are at least partially driven by changes in endothelial function.