BRACHIAL AND FEMORAL ARTERY BLOOD VELOCITY PROFILES ARE QUASI‐PARABOLIC DURING PHYSIOLOGIC STRESS

Fluid dynamics in conduit arteries are dependent upon physiologic state and vessel anatomy and it is often assumed constant laminar flow is always present. Aim To determine what extent antegrade and retrograde blood flow maintains a laminar velocity profile. Methods 3 subjects (22±2 yrs) completed a graded knee extension exercise test and a cold pressor test (CPT). Doppler ultrasound was used to determine the time‐average‐peak (TAP) and mean velocity (Vmean) for both antegrade and retrograde flow in the femoral (FA) and brachial arteries (BA). The slope of the TAP:Vmean relationship represented the velocity profile index (VPI). During laminar flow Vmean is 50% of TAP, therefore, changes in the velocity profile can be determined from changes in VPI (laminar, VPI = 0.5; plug‐like, VPI=1.0). Results During exercise, VPI of antegrade flow in the FA was 0.51±0.06. During CPT, VPI of antegrade flow (0.52±0.04) was similar to retrograde flow (0.50±0.05, P>0.05) in FA. Similarly, the VPI of antegrade flow (0.57±0.08) and retrograde flow (0.46±0.03) in BA during CPT were not different (P>0.05). There was no significant difference between VPI of FA and BA in any condition (P>0.05). Conclusion Our data suggests blood flow through two different conduit arteries under two different physiological stressors maintains a laminar velocity profile even when alternating between antegrade and retrograde flow.