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Repeatability of Superficial Femoral Artery Flow Mediated Dilation as induced by Calf Exercise
Author(s) -
King Trevor,
Schmitter Sarah,
Pyke Kyra
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.lb600
Subject(s) - medicine , repeatability , brachial artery , cardiology , blood flow , femoral artery , superficial femoral artery , ultrasound , shear stress , blood pressure , radiology , mathematics , materials science , statistics , composite material
In the brachial artery, a sustained (via handgrip exercise) shear stress stimulus elicits flow mediated dilation (FMD) which is stable and may relate to vascular health. The legs experience different patterns of shear stress than the arms, and are prone to different manifestations of cardiovascular disease, however a protocol to assess leg FMD as stimulated by exercise has yet to be established. The study purpose was to determine the repeatability of superficial femoral artery (SFA) FMD created using a sustained shear stress stimulus via calf exercise (LEX). 19 subjects (9 females) (age: 24 ± 2) performed 4 trials of dynamic LEX for 6 minutes to reach an individually determined shear rate (SR=blood velocity/artery diameter) target in a specially designed machine. SFA blood velocity and diameter were assessed via echo and Doppler ultrasound. FMD was quantified as the % change from baseline to peak 1 min mean diameter during LEX. Values are mean ± SD. There were no differences between trials in mean SR produced during the last 5 min of LEX (p = 0.17) or during the minute with the highest SR during LEX (p = 0.73). Trial 1 (T1) LEX FMD was significantly lower than T3, but not T2 or T4 (T1: 3.6 ± 2.7 %, T2: 3.9 ± 3.0 %, T3: 4.9 ± 3.4 %, T4: 4.5 ± 2.6 % FMD, p = 0.023). There was a trend for declining baseline diameter from T1 to T4 (impact of Trial p = 0.049), but no trials were significantly different (pairwise posthoc testing all p > 0.10), and there was no difference in peak 1 min diameter between trials (p=0.74). The interpretation of %FMD is complicated by changing baseline diameter, however these results suggest that when shear stress is controlled, the artery may dilate to a consistent peak diameter. Further research is required to determine the reasons for the instability in baseline SFA diameter and the utility of SFA LEX FMD. NSERC CFI