Abstract 19657: Brachial Microvascular Reactivity Measured With Near Infrared Spectroscopy Does Not Correlate With Brachial Vascular Reactivity Measured via Echographic Flow-Mediated Dilatation
Objective: Near infrared spectroscopy (NIRS) is used to evaluate peripheral microvascular reactivity. Whether NIRS correlates with brachial flow-mediated dilatation (FMD) is currently unknown. We studied the relationship between brachial vascular reactivity using FMD and brachial microvascular reactivity using NIRS in patients with various cardiovascular (CV) risk profiles.
Methods: Sixty nine patients with 3 different CV risk profiles (n=25 healthy subjects, n=19 metabolic syndrome patients, n=25 coronary heart disease patients) were recruited. Subjects were in the supine position and NIRS optodes were placed on the brachio-radialis muscle, on the right arm. Percent FMD and post-occlusive hypermia measured with NIRS were performed simultaneously during a 5-min arterial occlusion at 100 mmHg over the resting systolic blood pressure. High-resolution ultrasound examination of the brachial artery above the antecubital fossa was performed using a 7.5-MHz transducer during 1 minute at rest and 45 to 120 seconds after cuff release. Maximal % FMD, measured after cuff deflation, was used as the index of endothelium-dependent dilatation. Post-occlusive NIRS parameters included mVO2 (muscle oxygen consumption, ml O2/min/100 g) Hbmax (maximal total haemoglobin (Hb) hyperaemic response in %), O2Hb max (maximal oxyhaemoglobin amplitude in %), Tr O2Hb (time of recovery O2Hb signal, sec), T O2Hb max and Hbmax (time to max responses of O2Hb and total Hb, sec).
Results: Maximal % FMD values were 12.62±3.57 % for healthy patients, 10.82±3.68 % for patients with metabolic syndrome and 9.45±4.82 % for patients with coronary heart disease. No correlations were found between brachial % FMD and NIRS parameters when patient groups were analysed separately.
Conclusions: Microvascular reactivity as measured with NIRS is not related to brachial vascular reactivity measured by FMD following brachial artery occlusion.
- © 2010 by American Heart Association, Inc.