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Correlates of aortic compliance and brachial artery flow mediated vasodilatation in normal subjects
© Kodali et al; licensee BioMed Central Ltd. 2010
Published: 21 January 2010
Vascular endothelial dysfunction appears in early atherosclerosis and is associated with adverse cardiovascular outcomes, while decreased aortic compliance (AC) is associated with aging, systolic hypertension and left ventricular diastolic dysfunction. It is believed that diabetes, hypertension, hyperlipidemia and obesity contribute to endothelial dysfunction, often measured using brachial artery flow mediated vasodilation (F). However, the determinants of AC and its relationship to abnormal F are not well understood.
We developed techniques to non-invasively quantify both AC and F in a single MR study and used this approach to examine their concordance and correlates in normal and hyperlipidemic subjects.
Fifty one volunteers (26 females, 24 hyperlipidemics (11(46%) treated), age: 48.0 ± 4.3 yrs, body mass index (BMI) <28, LVEF:56.9 ± 5.7%), with informed consent were screened to exclude diabetes, hypertension, clinical cardiovascular disease and significant valvular dysfunction. Aortic pulse wave velocity (PWV) was assessed using through-plane phase-contrast gradient echo CMR imaging of ascending and descending aorta at the pulmonary artery level with VENC of 1.5 m/sec and AC derived: AC = 1/(ρ*PWV2). F was assessed using steady-state free precession bright blood imaging at rest and serially after blood pressure (BP) cuff deflation. A trained image analyst blinded to clinical variables manually planimetered lumen areas using commercial software (Circle CVI) with subpixel quantitation. F was calculated as maximal % brachial lumen area increase. Pearson's correlation coefficient was used to examine associations between C and F and their relationship to age, BMI, BP and cholesterol levels. Multivariate regressions were used to confirm univariate findings.
Mean ± Std deviation
55.3 ± 14.7
23.6 ± 2.6
Total Cholesterol mg/dl
210.7 ± 39.9
132.1 ± 35.2
56.8 ± 5.8
Systolic BP mm Hg
122.9 ± 20.4
Diastolic BP mm Hg
75.9 ± 10.2
Compliance (AC) 10-5/Pa
3.8 ± 3.9
Pearson's Correlation Coefficients for Aortic Compliance (AC)
Total Population (n = 51)
Females (n = 26)
Males (n = 25)
Hyperlipidemics (n = 24)
In normal and hyperlipidemic non-obese subjects, age is the most consistent correlate of reduced aortic compliance, while BMI, lipid levels and BP are significant correlates of reduced aortic compliance only in males. Brachial F appeared unrelated to age, gender, BP, lipid status and aortic compliance in this population. Larger studies are needed to further evaluate gender differences in aortic compliance.
This article is published under license to BioMed Central Ltd.