E-38 Free Communication/Poster - Vascular Function: JUNE 3, 2011 7:30 AM - 12:30 PM: ROOM: Hall B
Flow-mediated dilation (FMD) is a surrogate marker for endothelial function. The traditional calculation of FMD involves baseline arterial diameter prior to cuff inflation and peak arterial diameter following cuff release. Generally, arterial response during cuff inflation is not taken into consideration.
PURPOSE: To determine 1) the prevalence of brachial vasoconstriction during cuff inflation in a diverse population of subjects, 2) the impact of the vasoconstriction on the subsequent calculation of FMD, and 3) a role of arterial stiffness in determining the vasoconstriction.
METHODS: Low flow-mediated constriction (L-FMC), "traditional" FMD, and "modified" FMD that accounts for L-FMC by using inflation diameter in place of baseline diameter in calculating FMD, were studied in a total of 84 subjects. Subjects varied in age (18-62 years) and risk factor profiles for coronary artery disease.
RESULTS: During cuff inflation, 67% of subjects demonstrated vasoconstriction in the brachial artery whereas 33% showed vasodilation. When subjects were divided into young (≤35 years old) and older (≥50 years old) or into healthy and multiple risk factors, L-FMC and FMD were not different between the groups but modified FMD was significantly higher in young than in older groups (7.4±0.6% vs. 3.9±0.6%) and lower in the multiple risk factor group than in the healthy group (4.9±0.6% vs. 7.6±0.9%). L-FMC was modestly but significantly associated with FMD (r=0.26) and positively correlated with brachial artery pulse wave velocity (r=0.30).
CONCLUSIONS: Our results indicate that modified FMD that takes vasoconstriction into account may be a better indicator for discriminating high-risk populations and that arterial stiffening may play a role in determining L-FMC.