Flow-mediated vasodilation in response to matched levels of shear stress was significantly greater in the radial artery compared to the brachial artery (15.7% vs. 5.4%, P < 0.001).
Does the flow-mediated vasodilation response to matched levels of shear stress differ between the radial and brachial arteries in healthy young men?
The flow-mediated vasodilation response to shear stress is not uniform across differently sized vessels, being greater in the smaller radial artery compared to the brachial artery.
Absolute Event Rate: 15.7% vs 5.4%
p-value: p=<0.001
An inverse relationship between baseline artery diameter (BAD) and flow-mediated vasodilation (FMD) has been identified using reactive hyperemia (RH) to create a shear stress (SS) stimulus in human conduit arteries. However, RH creates a SS stimulus that is inversely related to BAD. The purpose of this study was to compare FMD in response to matched levels of SS in two differently sized upper limb arteries brachial (BA) and radial (RA) artery. With the use of exercise, three distinct, shear rate (SR) stimuli were created (SR = blood velocity/vessel diameter; estimate of SS) in the RA and BA. Artery diameter and mean blood velocity were assessed with echo and Doppler ultrasound in 15 healthy male subjects (19-25 yr). Data are means ± SE. Subjects performed 6 min of adductor pollicis and handgrip exercise to increase SR in the RA and BA, respectively. Exercise intensity was modulated to achieve uniformity in SR between arteries. The three distinct SR levels were as follows: steady-state exercise 39.8 ± 0.6, 57.3 ± 0.7, and 72.4 ± 1.2 s(-1) (P < 0.001). %FMD and AbsFMD (mm) at the end of exercise were greater in the RA vs. the BA at each shear level at the highest level: RA = 15.7 ± 1.5%, BA = 5.4 ± 0.8% (P < 0.001). The mean slope of the within-subject SR-%FMD regression line was greater in the RA (RA = 0.33 ± 0.04, BA = 0.13 ± 0.02, P < 0.001), and a strong within-subjects relationship between %FMD and SR was observed in both arteries (RA: r(2) = 0.92 ± 0.02; BA: r(2) = 0.90 ± 0.03). Within the RA, there was a significant relationship between baseline diameter and %FMD; however, this relationship was not present in the BA (RA: r(2) = 0.76, P < 0.001; BA: r(2) = 0.03, P = 0.541). These findings suggest that the response to SS is not uniform across differently sized vessels, which is in agreement with previous studies.
Jazuli et al. (Sat,) conducted a other in Healthy (n=15). Matched levels of shear stress in radial artery vs. Brachial artery was evaluated on %FMD at the highest shear level (p=<0.001). Flow-mediated vasodilation in response to matched levels of shear stress was significantly greater in the radial artery compared to the brachial artery (15.7% vs. 5.4%, P < 0.001).