Accurate quantitative measurements of brachial artery cross-sectional vascular area and vascular volume elastic modulus using automated oscillometric measurements: comparison with brachial artery ultrasound

Increasing vascular diameter and attenuated vascular elasticity may be reliable markers for atherosclerotic risk assessment. However, previous measurements have been complex, operator-dependent or invasive. Recently, we developed a new automated oscillometric method to measure a brachial artery's estimated area (eA) and volume elastic modulus (V-E). The aim of this study was to investigate the reliability of new automated oscillometric measurement of eA and V-E. Rest eA and V-E were measured using the recently developed automated detector with the oscillometric method. eA was estimated using pressure/volume curves and V-E was defined as follows (V-E = Delta pressure/(100 x Delta area/area) mmHg/%). Sixteen volunteers (age 35.2 +/- 13.1 years) underwent the oscillometric measurements and brachial ultrasound at rest and under nitroglycerin (NTG) administration. Oscillometric measurement was performed twice on different days. The rest eA correlated with ultrasound-measured brachial artery area (r=0.77, P<0.001). Rest eA and V-E measurement showed good reproducibility (eA: intraclass correlation coefficient (ICC)=0.88, V-E: ICC=0.78). Under NTG stress, eA was significantly increased (12.3 +/- 3.0 vs. 17.1 +/- 4.6mm(2), P<0.001), and this was similar to the case with ultrasound evaluation (4.46 +/- 0.72 vs. 4.73 +/- 0.75 mm, P<0.001). V-E was also decreased (0.81 +/- 0.16 vs. 0.65 +/- 0.11mmHg/%, P<0.001) after NTG. Cross-sectional vascular area calculated using this automated oscillometric measurement correlated with ultrasound measurement and showed good reproducibility. Therefore, this is a reliable approach and this modality may have practical application to automatically assess muscular artery diameter and elasticity in clinical or epidemiological settings.