ECG Gating is Not Required for Brachial Artery Flow-Mediated Dilation Measurement

Abstract

Objectives Brachial artery flow-mediated dilation is a well-established technique in the noninvasive assessment of endothelial function. Endothelial dysfunction is thought to be a potential precursor of atherosclerosis. In this study we compared the electrocardiogram (ECG) R-wave-gated acquisition of brachial artery measurement versus averaged measurement throughout the cardiac cycle. Study Design Cohort study: participant data was analyzed by use o the ECG-gated and nongated techniques and then analyzed. Materials and Methods Patients with peripheral vascular disease were studied. Upper limb ischemia was caused by inflating a blood pressure cuff at the right upper arm for 3 minutes. Brachial artery diameter measurements were taken in longitudinal section using a Sonosite Titan ultrasound machine with a 38 mm 5–10 MHz broadband linear array transducer. Results Twenty-three participants were tested (10 lower limb claudicants and 13 healthy volunteers). There was good correlation between ECG R-wave gated and nongated measurement R2 = 0.58 and Pearson's correlation coefficient was 0.762 ( p < 0.0001). Bland and Altman's method demonstrated good agreement and no heteroscedastic error. Conclusions We suggest that the use of automated image acquisition and analysis throughout the cardiac cycle to be preferable to ECG-gated acquisition. This may be important in the design of clinical trials involving noninvasive assessment of endothelial function.