Pujia A

Prognostic significance of endothelial dysfunction in hypertensive patients.

Background—Forearm endothelial dysfunction, characterized by an impaired vasodilating response to acetylcholine (ACh), may be associated with several cardiovascular risk factors, including essential hypertension. Although the prognostic value of coronary endothelial dysfunction has been demonstrated, that of forearm endothelial dysfunction is still unknown. Methods and Results—Endothelium-dependent and -independent vasodilation was investigated in 225 never-treated hypertensive patients (age, 35 to 54 years) by intra-arterial infusion of increasing doses of ACh and sodium nitroprusside. Patients were divided into tertiles on the basis of their increase in ACh-stimulated forearm blood flow (FBF) from basal: group 1, from 30% to 184%; group 2, from 185% to 333%; and group 3, from 339% to 760% increase from basal. During a mean follow-up of 31.5 of months (range, 4 to 84 months), there were 29 major adverse events at the cardiac (n=19), cerebrovascular (n=9), or peripheral vascular (n=1) level. Events included myocardial infarction, angina, coronary revascularization procedures, stroke, transient cerebral ischemic attack, and aortoiliac occlusive disease. Event rate per 100 patient-years was 8.17, 4.34, and 2.02 in the first, second, and third tertiles of peak percent increase in FBF during ACh infusion. The excess risk associated with an FBF increase in the first tertile was significant (relative risk, 2.084; 95% CI, 1.25 to 3.48;P =0.0049) after controlling for individual risk markers, including 24-hour ambulatory blood pressure. Conclusions—Our data suggest that forearm endothelial dysfunction is a marker of future cardiovascular events in patients with essential hypertension.

Association Between Intima-Media Thickness and Wall Shear Stress in Common Carotid Arteries in Healthy Male Subjects

BACKGROUND Atherosclerotic lesions lie in regions of low wall shear stress. No relationship between wall shear stress and intima-media thickness in vivo has been reported. Aims of the present study were to verify the reproducibility of wall shear stress measurement in vivo and to evaluate its association with intima-media thickness in the common carotid artery in healthy subjects. METHODS AND RESULTS Wall shear stress was calculated according to the following formula: Shear Stress = Blood Viscosity x Blood Velocity/Internal Diameter. Blood viscosity was measured by use of a cone/plate viscometer. Blood velocity, internal diameter, and intima-media thickness were measured by high-resolution echo Doppler. Twenty-one healthy male subjects were investigated. Peak and mean shear stress values were 29.5 +/- 8.2 and 12.1 +/- 3.1 dynes/cm-2 (mean +/- SD), respectively. Peak shear stress was inversely related to intima-media thickness (r = .62), age (r = .77), systolic blood pressure (r = .61), and body mass index (r = .59) (P < .001 for all coefficients). Mean shear stress yielded similar results. The relationship between shear stress and intima-media thickness was independent of age, blood pressure, and body mass index. The reproducibility, calculated by Kendalls W test, was statistically significant. CONCLUSIONS Our results demonstrate that common carotid artery wall shear stress measurement in vivo is reproducible. It inversely relates to intima-media thickness, age, systolic blood pressure, and body mass index. These findings confirm in vivo the role of shear stress in intima-media thickening.

In Vivo Association Between Low Wall Shear Stress and Plaque in Subjects With Asymmetrical Carotid Atherosclerosis

BACKGROUND AND PURPOSE It is known that atherosclerosis does not involve both carotid arteries to the same extent. Pathological investigations have demonstrated that lesions develop in regions of low wall shear stress. The aims of the present study were to verify the degree of carotid atherosclerosis asymmetry in a population-based study and to evaluate whether wall shear stress is lower in carotids with atherosclerotic lesions than in carotids without lesions. METHODS Participants in a cardiovascular disease prevention campaign (n = 1166) were screened for carotid atherosclerosis by echo-Doppler examination. Of these, 23 subjects who presented plaque in the common carotid or bulb of one side and no plaque in the contralateral carotid tree were enrolled for common carotid wall shear stress measurement. Shear stress was calculated according to the following formula: Shear Stress = Blood Viscosity x Blood Velocity/Internal Diameter. RESULTS Of the 1166 subjects screened, 400 (34%) had plaque and/or stenosis in the carotids. Ninety subjects had lesions exclusively in the right carotid, 111 had lesions exclusively in the left, 70 had lesions in both carotids but with different degrees of severity, and only 129 had similar lesions in both carotids. In the 23 subjects in whom wall shear stress was measured, peak shear stress was 18.7 +/- 4.1 and 15.3 +/- 4.0 dynes.cm-2 (mean +/- SD) (P < .0001) in the side without and the side with plaque, respectively. Mean shear stress yielded similar results. CONCLUSIONS The present results demonstrate that the atherosclerotic involvement of carotid arteries is usually asymmetrical and that wall shear stress is lower in the carotid arteries where plaques are present than in plaque-free arteries. These findings provide in vivo evidence for a strong association between shear stress and atherosclerotic lesions.

Evaluation of Common Carotid Hemodynamic Forces: Relations With Wall Thickening

The localization of atherosclerotic lesions is influenced by hemodynamic factors, namely, shear stress and tensive forces. The present study investigated the relationships between shear stress and circumferential wall tension and between these hemodynamic factors and the intima-media thickness (IMT) of the common carotid artery in healthy men. Fifty-eight subjects were studied. Shear stress was calculated as blood viscosityxblood velocity/internal diameter. Circumferential wall tension was calculated as blood pressurexinternal radius. Blood velocity, internal diameter, and IMT were measured by high-resolution echo-Doppler. Mean shear stress was 12.6+/-3.3 dynes/cm(2) (mean+/-SD; range, 4.8 to 20.4) and was inversely related with age, blood pressure, and body mass index (BMI). Mean circumferential wall tension was 3.4+/-0.6x10(4) dynes/cm (range 2.4 to 5.6) and was directly associated with age and BMI. IMT was inversely associated with shear stress (r=0.55, P<0. 0001) and directly associated with circumferential wall tension (r=0. 43, P<0.0001). Shear stress and circumferential wall tension were inversely correlated (r=0.66, P<0.0001). In multiple regression analysis, shear stress and (marginally) cholesterol were independently associated with IMT, whereas circumferential wall tension, age, and BMI were not. These findings confirm that common carotid shear stress varies among healthy individuals and decreases as age, blood pressure, and BMI increase. Our findings also demonstrate that circumferential wall tension is directly associated with wall thickness, age, and BMI and that shear stress is associated with common carotid IMT independent of other hemodynamic, clinical, or biochemical factors.

Awareness, treatment and control of hyperlipidaemia, hypertension and diabetes mellitus in a selected population of southern Italy

The purpose of the present study was to assess the degree of awareness, treatment and control of hyperlipidaemia compared with hypertension and diabetes mellitus in a selected population of southern Italy. All participants to a cardiovascular disease prevention campaign examined between April 1994 and July 1995 were screened for hyperlipidaemia, hypertension and diabetes mellitus. Subjects received also ECG, echo-Doppler of carotid arteries and filled in a questionnaire concerning personal and familial cardiovascular diseases, smoking habit and drug consumption. Of the 742 participants, 327 were found to have hypertension, 73 to have diabetes mellitus, 287 to have mild hyperlipidaemia and 322 to have moderate-severe hyperlipidaemia. Among hypertensive subjects, 60.2% were aware of their condition, 53.5% were treated and 15.6% had their blood pressure controlled at the recommended level (> 140/90 mmHg). Among diabetic subjects, 76.7% were aware, 64.4% treated and 19.2% reached fasting blood glucose level of less than 7.77 mmol/l (140 mg/dl). Only 24.0% of subjects with mild hyperlipidaemia were aware of their condition. Of the subjects found to have moderate-severe hyperlipidaemia, 64.9% were aware, 32.3% were treated and 9.0% had plasma cholesterol and triglycerides concentration of less than 6.45 and 5.65 mmol/l (250 and 500 mg/dl), respectively (cutoffs chosen to separate mild from moderate-severe hyperlipidaemia). These results show that mild hyperlipidaemia is almost neglected whereas awareness of moderate-severe hyperlipidaemia is quite widespread and comparable to that of hypertension and diabetes mellitus. Prevalence of treatment and control of moderate-severe hyperlipidaemia is, however, much lower than that of hypertension and diabetes.