Volume Elastic Modulus, Vascular Function, and Vascular Structure in Patients with Cardiovascular Risk Factors

Abstract

Aims: Volume elastic modulus (V_E), an index of arterial elasticity, and arterial diameter of the brachial artery can be automatically measured by a newly developed oscillometric device. We investigated the associations of V_E with flow-mediated vasodilation (FMD), an index of endothelium-dependent vasodilation, nitroglycerine-induced vasodilation (NID), an index of endothelium-independent vasodilation, and intima-media thickness (IMT) of the brachial artery and association of oscillometrically measured brachial artery diameter with ultrasonographically measured brachial artery diameter in patients with cardiovascular risk factors.

Methods: Oscillometric measurements of V_E and brachial artery diameter and ultrasound measurements of brachial artery diameter, FMD, NID, and IMT of the brachial artery were performed in 50 patients with cardiovascular risk factors.

Results: The mean values were 2.1±0.4 mmHg/% for V_E, 0.31±0.05 mm for brachial IMT, 4.48±0.70 mm for oscillometric brachial artery diameter, and 4.30±0.55 mm for ultrasound brachial artery diameter. V_E significantly correlated with brachial IMT (r=0.51, P＜0.001), whereas there was no significant correlation of V_E with FMD (r=-0.08, P=0.58) or NID (r=0.07, P=0.61). Multivariate analysis revealed that V_E was significantly associated with brachial IMT (β=0.33, P=0.04). Oscillometric brachial artery diameter significantly correlated with ultrasound brachial artery diameter (r=0.79, P＜0.001). The Bland-Altman plot showed good agreement between oscillometric brachial artery diameter and ultrasound brachial artery diameter (mean difference, -0.17 mm; limits of agreement, -1.03 mm to 0.69 mm).

Conclusions: In patients with cardiovascular risk factors, V_E may represent atherosclerotic structural alterations of the vascular wall but not vascular function. The accuracy of oscillometric measurement of brachial artery diameter is acceptable.

Keywords: Brachial artery diameter; Endothelium-dependent vasodilation; Endothelium-independent vasodilation; Intima-media thickness; Volume elastic modulus.