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

Abstract

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 (VE). The aim of this study was to investigate the reliability of new automated oscillometric measurement of eA and VE. Rest eA and VE were measured using the recently developed automated detector with the oscillometric method. eA was estimated using pressure/volume curves and VE was defined as follows (VE=Δ pressure/ (100 × Δ area/area) mm Hg/%). 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 VE measurement showed good reproducibility (eA: intraclass correlation coefficient (ICC)=0.88, VE: ICC=0.78). Under NTG stress, eA was significantly increased (12.3±3.0 vs. 17.1±4.6 mm2, 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). VE was also decreased (0.81±0.16 vs. 0.65±0.11 mm Hg/%, 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.

Anatomical and Functional Estimations of Brachial Artery Diameter and Elasticity Using Oscillometric Measurements with a Quantitative Approach

“…The newly developed device is the Health Chronos TM-2771 prototype (A&D Company, Tokyo, Japan; fig. 1 , 2 ) [22,25] . This system estimates the absolute value of cross-sectional vascular area instead of vascular volume.…”

“…Vascular elastic modulus (V E ) is the pressure change required for 100% increase in vascular diameter or pressure change per square centimeter for 100% extension [21] . V E is defined as the change in the BP-CP (cuff pressure) difference (transmural pressure) per 1% increase in the cross-sectional area at P1, where P1 = P0 + 40 mm Hg [22] . The highest CP can cause complete collapse of the brachial artery.…”

“…These approaches obtained BP through arterial catheter or applanation tonometry, approaches that were either complex or invasive and therefore not suitable for clinical practice. For these reasons, we aimed to develop new vascular anatomical and functional measurements using an oscillometric approach [22] .…”

“…The highest CP may be slightly greater than BP. Therefore, P0 at diastole on the transmural pressure axis was set at less than zero and is associated with complete vascular occlusion [22] . Therefore, vascular elasticity is only minimally influenced by BP at the time of measurement and can be measured through an oscillometric approach [11,21] .…”

“…In contrast, vascular elasticity is not considered to be influenced by a patient's BP at the time of measurement and can be measured through an oscillometric approach [11,21] . We therefore aimed to make new vascular anatomical and functional measurements using an oscillometric approach [22] .…”