Endothelial Function Assessment by Ultrasonography. Effect of Age, Sex and Cardiovascular Risk Factors

pp 523-532

Abstract

Background

The hyperemic flow is the responsible for the endothelium-dependent post-ischemic vasodilation through the nitric oxide release in the brachial artery. The aim of the present study was to assess the endothelium-dependent arterial dysfunction in a general population without symptoms or clinical manifestation of cardiovascular disease, with or without cardiovascular risk factors, and the influence of age, sex and the cardiovascular risk factors.

Material and method

Brachial artery diameter and flow were measured by echo-Doppler ultrasonography before and after reactive hyperemia in 165 subjects (mean age 52.15 ± 16.59 years), 87 men, 60 of them without cardiovascular risk factors and 105 with high cholesterol(LDL > 160 mg%), smoking (+ 1 cigarette daily), arterial hypertension (> 140/90 mmHg), obesity (body mass index > 30) and sedentarism. After allowing the return to baseline, 0.3 mg sublingual nitroglycerin was administered and brachial artery diameter and flow were measured again. Multiple comparisons were made by ANOVA and matched comparisons by "t" test and Mann Whitney test. Simple and multiple linear regression were performed to evaluate age changes.

Results

In general population post-ischemic arterial diameter increased by 14.5 ± 12%, p < 0.001 (men 14.2 ± 14%, women 14.9 ± 10%, NS), and flow by 50.3 ±66.6% (men 50.8 ±74.3, women 41.8 ± 57.3%, NS). In60 subjects with no risk factors arterial diameter increased by 11.9 ± 9% while in 105 subjects with one or more risk factors arterial diameter increased by 19.1 ± 15% (p < 0.002). Arterial dilatation was impaired principally by: smoking 6.41% (p <0.0005), high cholesterol 9.14% (p < 0.001) and hypertension 11.7% (p < 0.01). Post-ischemic arterial dilatation was independently related to age. Post nitroglycerin diameter and flow increased significantely, with the same magnitude in both groups.ConclusionsPost-ischemic vasodilation and hyperemic flow of the brachial artery assess endothelial function.Cardiovascular risk factors showed lower response of the reactive hyperemia in subjects with no symptoms or clinical manifestation of cardiovascular disease. The response was highly impaired mainly in smokers, hypercholesterolemic and hypertensive subjects. The vasodilation showed decrease values with age, independent of sex or cardiovascular risk factors. Artery responses to endothelium-dependent dilation is a non-invasively and reproductible technique, that permits detect cardiovascular risk for primary and secondary prevention treatments.