Background and hypothesis: Brachial artery flow-mediated dilation (FMD), a noninvasive, widely used clinical index of endothelial function and magnitude of FMD, has been reported to be closely related to many coronary risk factors and coronary atherosclerosis. However, there has been no study that examines the diurnal change of FMD. We designed this study to reveal the diurnal variation of FMD in healthy volunteers. Methods:We examined FMD in response to reactive hyperernia by high resolution ultrasound in 13 healthy young men (age 25-32) at four different times over the course of a day.Results: Mean measures of brachial artery FMD was 4.0% at 8:00, 5.3% at 12:00, 9.7% at 17:OO, and 6.9% at 2190 hours. Flow-mediated dilation at 8:OO and at 12:OO hours was significantly lower than that at 17: OO (p c 0.05).Conclusions: These results show that endothelial function has diurnal variation and is significantly attenuated in the morning. Morning attenuation of endothelial function should be recognized in clinical research and may play an important role in the circadian variation of the occurrence of acute cardiovascular events.

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Background: While both flow-mediated vasodilation (FMD) in the brachial artery (BA), which measures endothelium-dependent vasodilatation, and intima-media thickness (IMT) in the carotid artery are correlated with the prognosis of coronary artery disease (CAD), it is not clear which modality is a better predictor of CAD. Furthermore, it has not been fully determined whether either of these modalities is superior to conventional ST-segment depression on exercise stress electrocardiogram (ECG) as a predictor. Thus, the goal of the present study was to compare the predictive value of FMD, IMT, and stress ECG for CAD prognosis.

SummaryBackground: Carotid intima-media thickness (IMT), pulse wave velocity (PWV), and the ankle brachial index (ABI) are widely used noninvasive modalities for evaluating atherosclerosis.Hypothesis: The aim of this study was to determine the relationship of carotid IMT, PWV, and ABI with the severity of coronary artery disease (CAD), expressed as the Gensini score, and the presence of coronary risk factors.Methods: We examined 205 consecutive patients (mean age 65 ± 12 years) who were clinically suspected of having CAD and were scheduled to undergo coronary angiography. Carotid intima-media thickness, brachial-ankle PWV (baPWV), and ABI were measured in all subjects before they underwent coronary angiography.Results: Of the 205 patients, 124 patients were diagnosed as having CAD based on the presence of > 50% stenosis in a major coronary artery; the remaining 81 patients did not have CAD. A relatively good correlation was obtained between carotid IMT and the Gensini score (R = 0.411, p < 0.0001), whereas baPWV correlated only weakly with the Gensini score (R = 0.203, p = 0.0035), and ABI did not correlate with it. A multiple regression analysis revealed that the Gensini

Cigarette smoking has been associated with endothelial dysfunction including impaired endothelium-dependent flow-mediated dilation (FMD). In cigarette smokers, increased oxygen-derived free radicals have been suspected of being one of the major causes of endothelial dysfunction, owing possibly to the inactivation of nitric oxide by free radicals. Vitamins C and E are widely used antioxidant vitamins, which have also been reported to effectively improve the endothelial function in several conditions. To test the effect of moderate-term oral antioxidant vitamin supplementation on the endothelial function in smokers, the authors evaluated the combined effect of vitamins C and E, administered in normal dosages, on FMD in young male smokers. A prospective interventional study was performed. In 15 healthy male subjects (mean age, 24.4 +/-2.5 years old). They studied FMD in the brachial artery by using high-resolution ultrasound. The vascular effects of moderate-term oral supplementation with vitamin C (1.0 g/day) and vitamin E (500 mg/day) were determined during reactive hyperemia, which causes endothelium-dependent FMD. They performed a vascular function study 3 times including before vitamin supplement, after 25 days of vitamin supplement, and 4 weeks after the cessation of the vitamin supplement. The flow-mediated dilator response measurements were repeated twice a day before vitamin supplements, and the repeatability obtained from these measurements was found acceptable (variability of FMD <2%). The oral antioxidant vitamin supplement significantly restored FMD (3.8 +/-2.2% vs 5.9 +/-2.5%; p<0.05), however, this effect disappeared 4 weeks after the vitamin supplementations ended. The combined usual dosage of vitamins C and E supplements was found to improve the endothelial function in chronic smokers.