1. Repeatability of measurements of arterial compliance and flow-mediated dilation of the brachial artery has been infrequently reported, despite increasing use in interventional and risk-factor modification studies. Furthermore, little is known about the interrelationships of the various indices. The purposes of this study were to determine the repeatability and interrelationships of a range of arterial indices.2. Fifty healthy volunteers, 20 men and 30 women, aged 20-70 (mean 46.5) years, were studied on two occasions, using an identical protocol, at a mean interval of 2.5 weeks. Tonometry, ultrasound and Doppler technique were used to measure the following: carotid wall intima-media thickness (IMT), total systemic artery compliance (SAC), arterial pulse wave velocity [PWV aorto-femoral (A-F), and femoral-dorsalis pedis (F-D)], carotid distensibility coefficient (DC) and carotid augmentation index (AI). Brachial flow-mediated dilation was measured in 30 subjects with analysis of diameter change for 4 min post ischaemia.3. There were no systematic differences over the observed range of measurements for any of the reported parameters. Coefficients of variation were as follows: IMT 2.8%, SAC 9.2%, PWV(A-F) 3.2%, PWV(F-D) 5.0%, DC 10.0%, AI 1.3%. Brachial flow-mediated dilation curves were not different between visits; changes were maximum 60-s post ischaemia. All indices of arterial compliance were significantly correlated with age. The three different indices of central arterial compliance [SAC, PWV(A-F) and AI] were significantly correlated with carotid intima-media thickness.4. Under controlled experimental conditions there was good repeatability of measurements of indices between sessions of both intrinsic and functional arterial mechanical properties (central and carotid arterial compliance, intima-media thickness and brachial flow-mediated dilation). Sample size tables for clinical trials using these indices are presented.
Abstract-Hormone replacement therapy (HRT) appears to be cardioprotective in postmenopausal women; however, concerns exist over its thrombogenic effects. To address the effects of combined HRT on coagulation and fibrinolysis, we have measured circulating markers of these processes in a double-blind placebo-controlled trial. Forty-two healthy postmenopausal women aged 50 to 75 years received continuous combined HRT with 2 mg estradiolϩ1 mg norethisterone or placebo for 6 weeks. Hormone profiles were measured at baseline, and lipid and hemostatic parameters were measured at baseline and after 6 weeks of therapy. Baseline characteristics were similar in the 2 groups. With change from baseline the main outcome measure, HRT increased the markers of coagulation (prothrombin fragments 1ϩ2, 0.
Abstract-In the present study, we examined the relationships among carotid blood pressure, arterial geometry, and wall stress and determined the impact of hypertension, smoking status, and their interaction on these relationships. The study involved 679 subjects aged 49 to 82 years: 372 smokers (190 men and 182 women) and 307 nonsmokers (110 men and 197 women). Blood samples were taken to determine total cholesterol levels. Central pulse pressure was derived from measured brachial artery pressure with a linear regression equation from data obtained in a subgroup of 276 subjects that related brachial and carotid pulse pressures; the latter was measured with applanation tonometry. Carotid intima-media thickness (IMT), lumen diameter (D), and stiffness index (SI) were determined with high-resolution B-mode ultrasound. Mean and pulsatile circumferential stress ( C ) was calculated according to the Laplace relationship. Indexes of arterial geometry and function were adjusted for age, height, and heart rate. Hypertension (treated and/or screening blood pressure of Ͼ140/90 mm Hg) was present in 71 nonsmokers and 186 smokers. Nonsmokers and smokers did not differ in blood pressure and cholesterol levels. Hypertension and smoking individually and interactively significantly increased adjusted IMT, D, and SI. The radius-to-wall thickness ratio (R/IMT) (where RϭD/2) and C were increased in hypertensives. SI was correlated with IMT (rϭ0.56, PϽ0.001); radius-to-wall thickness ratio was inversely correlated with central pulse pressure (rϭϪ0.38, PϽ0.001). Smoking did not influence these relationships. In conclusion, carotid artery wall remodeling appears to follow Laplace's law but is insufficient to prevent an increase in circumferential stress in hypertensive subjects. Unlike hypertension, smoking does not influence the lumen-to-wall ratio but has a significant effect on wall stiffness. (Hypertension. 2001;37:6-11.)
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