Brachial artery dilatation responses in healthy children and adolescents

Relation of apolipoprotein E polymorphism to markers of early atherosclerotic changes in young adults--the Cardiovascular Risk in Young Finns Study

BACKGROUND

Carotid artery intima-media thickness (IMT), which is measured by ultrasound, is used in the assessment of early atherosclerotic changes, and has been associated with apolipoprotein E (APOE) polymorphism in many studies comprising elderly subjects. However, results are still inconclusive and data relating to young adults are missing. Whether common APOE polymorphism is related to carotid IMT was studied in a population of young adults. Also brachial flow-mediated dilatation (FMD) and carotid artery compliance (CAC) were determined to clarify their relation to this genetic factor.

METHODS AND RESULTS

A total of 1,188 young adults (aged 24-39 years) participating in the Cardiovascular Risk in Young Finns Study with complete data of common APOE polymorphism underwent a carotid and brachial ultrasound. Patients' lipid levels and blood pressure were also examined. There was no significant association between the APOE phenotypes and carotid IMT, brachial FMD or CAC either in young men or in young women. The results were similar for systolic and diastolic blood pressure. In the same population, the well-known association between APOE phenotypes and lipids was seen.

CONCLUSIONS

Common APOE polymorphism does not seem to be an independent genetic determinant of carotid IMT, brachial FMD or CAC.

Tobacco Smoke Exposure Is Associated With Attenuated Endothelial Function in 11-Year-Old Healthy Children

BACKGROUND

Passive smoking is associated with early arterial damage in adults, but its effect on endothelial function in children is unknown.

METHODS AND RESULTS

Serum cotinine concentration was measured annually in children between 8 and 11 years of age who had participated since infancy in a randomized, prospective atherosclerosis prevention trial (Special Turku Coronary Risk Factor Intervention Project for children [STRIP]). At age 11, endothelium-dependent flow-mediated vasodilatory responses of the brachial artery were examined with high-resolution ultrasound in 402 children. These children were divided into 3 groups according to serum cotinine concentrations: the noncotinine group (nondetectable cotinine, n=229), the low cotinine group (cotinine between 0.2 and 1.6 ng/mL, n=134), and the top decile cotinine group (cotinine > or = 1.7 ng/mL, n=39). Longitudinal cotinine data in children aged 8 to 11 years and ultrasound studies were available in 327 children. At age 11, the increase in cotinine concentration was associated with attenuated peak flow-mediated dilation response (mean+/-SD: the noncotinine group 9.10+/-3.88%, the low-cotinine group 8.57+/-3.78%, and the top-decile cotinine group 7.73+/-3.85%; P=0.03 for trend). Similarly, total dilation response (the area under the dilation response versus time curve between 40 and 180 seconds after hyperemia) was affected by the cotinine level (P=0.02 for trend). These trends were not explained by traditional atherosclerosis risk factors. Arterial measures and passive smoking showed even stronger associations when longitudinal cotinine data were used (peak flow-mediated dilation, P=0.01 for trend; total dilation response, P=0.008 for trend).

CONCLUSIONS

Exposure to environmental tobacco smoke confirmed by serum cotinine concentrations impairs endothelial function in a dose-dependent manner in 11-year-old children.

Carotid artery compliance in users of plant stanol ester margarine

OBJECTIVE

To investigate the effects of stanol ester margarine use in healthy subjects on arterial compliance, endothelial function and intima-media thickness.

DESIGN

Case-control study comparing regular stanol ester margarine users to non-users.

SETTING

Occupational health service clinic.

SUBJECTS

We recruited 50 cases and 50 controls (mean age 51+/-8, range 26-65 years). All subjects were non-smokers and the study groups were matched for age and sex. As cases, we invited subjects who had been using regularly (daily) plant stanol ester margarine for a period of 2 years or longer. Non-invasive ultrasound was used to measure carotid artery compliance, carotid intima-media thickness and brachial artery flow-mediated endothelial dependent vasodilatation.

RESULTS

The carotid artery compliance was non-significantly higher in cases compared with controls, 1.84+/-1.02 vs 1.58+/-0.76 %/10 mm Hg (P=0.13). The difference in compliance became statistically significant (P=0.04) when the unbalance between the groups in family history of coronary artery disease and years of education were taken into account. There was also a significant dose-response relationship between stanol margarine use and carotid compliance, longer use being associated with higher compliance. Serum lipoproteins, blood pressure, flow-mediated dilation and intima-media thickness values did not differ between cases and controls.

CONCLUSION

These data raise the possibility that regular stanol ester margarine use may be associated with beneficial changes in arterial compliance. Intervention studies are needed to test this hypothesis and to reveal possible mechanisms.

Decreased nitrate-mediated dilatation in patients with coronary artery ectasia: an ultrasonographic evaluation of brachial artery

BACKGROUND

Coronary artery ectasia has been defined as localized or diffuse nonobstructive lesions of the epicardial coronary arteries with a luminal dilation exceeding the 1.5-fold of normal adjacent segment or vessel diameter. Although coronary artery disease is supposed to be responsible for more than 50% of coronary ectasia, the precise pathology of coronary artery ectasia is not clearly understood. The brachial artery ultrasound test for flow-mediated endothelial-dependent vasodilatory function includes administration of sublingual nitrates to examine the vasodilating effect of an exogenous source of nitric oxide. In the present study, we aimed to compare flow-mediated and nitrate-mediated responses of brachial artery in patients with coronary artery ectasia and patients with coronary artery disease.

MATERIALS AND METHODS

Thirty-six consecutive patients with coronary artery ectasia in combination with coronary artery disease and 42 age-matched and sex-matched patients with coronary artery disease alone were included in the study. Flow-mediated and nitrate-mediated dilatations were measured in all patients using a high-resolution B-mode ultrasonographic system.

RESULTS

Baseline brachial artery diameters in patients with coronary artery ectasia were not statistically different from those in patients with coronary artery disease (4.2+/-0.6 vs. 4.0+/-0.6 mm, respectively, P=0.16). Although the forearm flow-mediated dilatation of the patients with coronary artery ectasia did not differ from that of patients with coronary artery disease alone (5.5+/-3.8 vs. 4.8+/-3.6%, respectively, P=0.41), nitrate-mediated dilatation was significantly lower than that of patients with coronary artery disease alone (7.9+/-5.2 vs. 10.9+/-5.4%, respectively, P=0.02).

CONCLUSION

We have shown that patients with coronary artery ectasia have decreased nitrate-mediated response of brachial artery compared with patients with coronary artery disease alone, suggesting more severe dysfunction or, possibly, destruction of the media layer in coronary artery ectasia than in coronary artery disease.

Myocardial and peripheral vascular functional adaptation to exercise training

Exercise training seems to restore impaired vascular function in both peripheral and myocardial vessels in patients with coronary artery and peripheral vascular disease or in patients with risk factors for these diseases. However, the results on the effects of exercise training on vascular function in apparently healthy subjects are controversial. We studied the effects of long-term volitionally increased physical activity on peripheral and myocardial vascular function in nine young healthy male monozygotic twin pairs discordant for physical activity and fitness. The brothers were divided into more (MAG) and less active groups according to physical activity and fitness. The difference between groups in VO(2max) was 18+/-10% (P<0.001). Myocardial perfusion at rest, during adenosine-induced vasodilatation and during cold-pressor test and myocardial oxygen consumption were measured with positron emission tomography. In addition, endothelial function was measured using ultrasound in brachial and left anterior descending coronary arteries, and standard echocardiographic measures were taken. No differences were observed in myocardial perfusion measurements between groups. MAG tended to have a lower oxygen extraction fraction (P=0.06), but oxygen consumption was similar between the groups. No differences were found in coronary artery, myocardial resistance vessel or peripheral endothelial function between groups. These results suggest that when the effects of heredity are controlled, myocardial perfusion reserve and endothelial function, both in peripheral arteries and myocardial vessels, are not enhanced by increased physical activity and fitness in young healthy adult men.

Omega-3 fatty acids: role in cardiovascular health and disease

Dietary omega-3 polyunsaturated fatty acids, eicosapentaenoic and docosahexaenoic acids, play an important role in cardiovascular health and disease. Clinical trials provide substantial evidence to support current dietary recommendations for omega-3 fatty acids in cardiovascular disease management. The cardioprotective benefits of omega-3 fatty acids may be attributed to multiple physiological effects on lipids, blood pressure, vascular function, cardiac rhythms, platelet function, and inflammatory responses. The metabolism of omega-3 fatty acids, physiological effects, and clinical considerations with current dietary recommendations and sources of omega-3 fatty acids are presented.

Determinants of short-term variation in arterial flow-mediated dilatation in healthy young men

Brachial artery FMD (flow-mediated dilatation) is widely used as a marker of systemic arterial endothelial function. FMD, however, shows considerable 25% day-to-day variation that hinders its clinical use. The reasons for this variability are poorly characterized. Therefore the present study was designed to clarify factors responsible for the hourly variation in endothelial function, including consuming a low-fat meal and circadian rhythms in endogenous hormonal levels. Brachial artery FMD, along with serum glucose, triacylglycerols (triglycerides) and levels of several hormones were measured six times per day on two separate days 1 week apart. On one day, the subjects (healthy males: n=12, mean age, 24 years) ate a light breakfast and a standardized lunch (23.5% fat, 48.7% carbohydrate and 27.8% protein). On the other day, they had a similar breakfast after which they fasted. Postprandial FMD values (both after breakfast and after lunch) were similar to baseline FMD. FMD showed a 28% hourly variation and 27% weekly variation. Variation in plasma levels of insulin (P=0.02) associated negatively and DHPG (3,4-dihydroxyphenylglycol) (P=0.001), a marker of sympathetic nervous activation, associated positively with variation in FMD. The effects of DHPG and insulin on FMD were independent of changes in baseline brachial artery diameter, although DHPG was also inversely associated with baseline diameter. Eating a regular low-fat meal does not have any measurable effects on brachial artery endothelial function. These data suggest that strict requirements for fasting conditions may be unnecessary when measuring peripheral endothelial function using the ultrasound technique. Circadian variation in serum insulin and sympathetic tone are physiological determinants of endothelial function.

Endothelial Function in Healthy 11-Year-Old Children After Dietary Intervention With Onset in Infancy

Background— Early childhood introduction of nutritional habits aimed at atherosclerosis prevention reduces children’s serum total cholesterol concentration, but its effect on vascular endothelial function is unknown.

Methods and Results— Between 1990 and 1992, we randomized healthy 7-month-old infants (n=1062) to intervention (low-saturated-fat diet) and control (unrestricted diet) groups. At the age of 11 years, endothelium-dependent (flow-mediated) and endothelium-independent (nitrate-mediated) vasodilatory responses of the brachial artery were measured with high-resolution ultrasound in 179 intervention and 190 control children. The effect of intervention on endothelial function was significant in boys ( P =0.0034) but not in girls ( P =0.69). The maximum endothelium-dependent dilation response (mean±SD) was 9.62±3.53% and 8.36±3.85% in intervention boys and control boys and 8.84±4.00% and 8.44±3.60% in intervention girls and control girls, respectively. Intervention had no effect on nitrate-mediated dilation. The difference in endothelial function in boys remained significant after adjustment for current serum total or LDL cholesterol but became nonsignificant after adjustment for mean cholesterol measured under 3 years of age (adjusted means: 9.46% [CI 8.68% to 10.24%] versus 8.54% [CI 7.75% to 9.32%], P =0.11).

Conclusions— A low-saturated-fat diet introduced in infancy and maintained during the first decade of life is associated with enhanced endothelial function in boys. The effect is explained in part by the diet-induced reduction in serum cholesterol concentration.

Increased arterial stiffness in children on haemodialysis

BACKGROUND

Measures of aortic stiffness--aortic pulse wave velocity (PWV) and augmentation index (AIx)--have been shown to be powerful predictors of survival in adult haemodialysis (HD) patients. Very few data have been reported regarding arterial stiffness in paediatric renal populations.

METHODS

PWV and aortic AIx were determined from contour analysis of arterial waveforms recorded by applanation tonometry using a SphygmoCor device in 14 children on HD (age = 14.1 years) and in 15 age, height matched children controls.

RESULTS

Pre-HD AIx (29.7 +/- 15.4%) and PWV (6.6 +/- 1.0 m/s) were significantly higher compared with children controls (8.3 +/- 8.0% and 5.4 +/- 0.6 m/s, respectively, P < 0.0001). The only significant difference between normal and HD children was BP level: 103/61 vs 114/72 mmHg, P < 0.05. In children of HD patients, a multiple linear regression model including BP, age, height, weight, Ca and P levels as independent variables accounted for 57% of the variability in AIx. Dialysis had no impact on AIx (post-HD: 28.5 +/- 12.7%) or on PWV (post-HD: 6.7 +/- 0.8 m/s).

CONCLUSIONS

We show, in this first-ever report of increased arterial stiffness in children on dialysis, that end-stage renal disease is associated with abnormalities in arterial wall elastic properties, comparable with adult levels, even in childhood. Most importantly, the absence of a discernible amelioration with dialysis implies that purely structural and not functional alterations lie behind the increased arterial stiffness.

Arterial intima-media thickening and endothelial dysfunction in obese Chinese children

We studied ultrasonographic signs of early atherosclerosis in relation to established risk factors of cardiovascular disease in 43 obese school-age children compared to 28 non-obese controls. The groups did not show significant differences in age, gender ratio and body height. Mean carotid intima-media-thickness (IMT), carotid haemodynamic parameters, flow-mediated dilatation of the brachial artery (FMD), and biochemical markers of dyslipidaemia were measured and correlated. IMT was significantly increased (0.62 mm vs. 0.46 mm, P <0.001) and FMD was markedly reduced (10.9% vs. 18.8%, P <0.001) in the obesity group. Differences in IMT and FMD persisted after adjustment for Body Mass Index (BMI) and blood pressure on ANCOVA. BMI was highly associated with increased IMT ( r =0.58, P <0.01) and reduced FMD ( r =-0.42, P <0.01), as were blood levels of total cholesterol, LDL cholesterol and Apo B.

CONCLUSION

Childhood obesity seems to contribute to the development and progression of early atherosclerosis, particularly in combination with hypertension and dyslipidaemia. In order to prevent coronary atherosclerosis and other cardiovascular complications, it is vital to control obesity starting from childhood. Ultrasonography of the arterial wall may be used in a clinical setting to identify high-risk patients among severely obese children.

Inflammation, insulin, and endothelial function in overweight children and adolescents: the role of exercise

OBJECTIVES

To assess subclinical inflammation, fasting insulin, and endothelial function before and after exercise in overweight children and adolescents.

STUDY DESIGN

Twenty-five children (body mass index [BMI] >85th percentile) were assessed for brachial artery flow-mediated dilation (FMD), nitroglycerin-induced dilation, C-reactive protein (CRP), lipids, glucose, insulin, oral glucose tolerance, body composition, aerobic fitness (peak oxygen uptake [VO 2 peak]), and blood pressure. Twenty of these persons were equally and randomly assigned to either 8 weeks of stationary cycling or to a non-exercising control group.

RESULTS

A baseline correlation was found between CRP and fasting insulin (r = 0.62; P < .001), which remained significant after adjusting for baseline variables (r = 0.53; P < .05). After 8 weeks, significant improvements were observed in the exercise group compared with the control group for VO 2 peak (exercise group = 21.8 +/- 2.1 to 23.2 +/- 1.5 mL/kg/minute vs control group = 23.4 +/- 1.6 to 20.9 +/- 2.2 mL/kg/minute; P < .05), high-density lipoprotein (HDL) cholesterol (exercise group = 1.02 +/- 0.03 to 1.10 +/- 0.04 mmol/L vs control group = 1.08 +/- 0.07 to 0.99 +/- 0.09 mmol/L; P < .05), and FMD area under the curve (AUC) (exercise group = 746 +/- 66 to 919 +/- 94 %*sec vs control group = 731 +/- 102 to 515 +/- 73 %*sec; P < .05).

CONCLUSIONS

In overweight children and adolescents, CRP is independently associated with fasting insulin. Eight weeks of aerobic exercise improves fitness, HDL cholesterol, and endothelial function in this group.

Interrelations between brachial endothelial function and carotid intima-media thickness in young adults: the cardiovascular risk in young Finns study

BACKGROUND

Endothelial vasodilator dysfunction and carotid intima-media thickening (IMT) are 2 indicators of subclinical cardiovascular disease. We examined their correlation and interaction with risk factors in a large, community-based cohort of young adults.

METHODS AND RESULTS

As part of the longitudinal Cardiovascular Risk in Young Finns Study, we measured endothelium-dependent brachial artery flow-mediated dilatation (FMD) and carotid artery IMT by ultrasound in 2109 healthy adults aged 24 to 39 years. FMD was inversely associated with IMT (P< or =0.001) in a multivariate model adjusted for age, sex, brachial vessel size, and several risk variables. The subjects with age- and sex-specific FMD values in the extreme deciles were classified into groups of impaired (n=204, FMD=1.1+/-1.4%, mean+/-SD) and enhanced (n=204, FMD=16.3+/-2.9%) FMD response. The number of risk factors was correlated with increased IMT in subjects with an impaired FMD response (P<0.05) but not in subjects with an enhanced FMD response (P>0.2).

CONCLUSIONS

Brachial FMD is inversely associated with carotid IMT. The number of risk factors in young adults is correlated with increased IMT in subjects with evidence of endothelial dysfunction, but not in subjects with preserved endothelial function. These observations suggest that endothelial dysfunction is an early event in atherosclerosis and that the status of systemic endothelial function may modify the association between risk factors and atherosclerosis.

Gender influences endothelial-dependent arterial dilatation via arterial size in youth

BACKGROUND

Reduced endothelial-dependent arterial dilatation (EDAD) has been suggested as an early marker of arteriosclerosis, since it has been reported to correlate with known cardiovascular disease (CVD) risk factors. It is unclear, however, whether gender plays a mediating or a moderating role in these relationships. The aim of this study was to evaluate the influence of gender on EDAD in youth at risk for CVD.

METHODS

The sample population of 261 individuals (mean age, 20 yr; SD, 3 yr) consisted of 148 African Americans, 113 European Americans, 133 males, and 128 females, all with a verified family history of CVD (ie, hypertension, myocardial infarction). Anthropometrics, sociometrics, hemodynamics, brachial artery diameter, left ventricular mass, and relative wall thickness were measured and used as independent variables. EDAD (dependent variable) was expressed as percent (%) change of brachial artery diameter to reactive hyperemia induced by pressure cuff occlusion and release. Artery diameters were calculated via an automated border detection system.

RESULTS

Percent EDAD change was inversely related to initial diameter of the brachial artery. Mean percent EDAD change was 14.37% for female subjects compared with 10.48% for male subjects. The gender difference was a function of smaller initial artery size in the female subjects. When initial diameter and gender were considered simultaneously within a multivariate model, the gender effect was eliminated. Although a large prediameter effect remained, the relationship between prediameter and EDAD was greater in female than in male subjects (ie, interaction/moderating effect).

CONCLUSION

The data suggest that the smaller the artery is, the more it will dilate. Further EDAD investigations are needed to predict arteriosclerosis, taking into account of the gender difference in vessel size.

Determinants of arterial nitrate-mediated dilatation in children: role of oxidized low-density lipoprotein, endothelial function, and carotid intima-media thickness

BACKGROUND

Impaired arterial dilatation response to nitroglycerin has been observed in adults with risk factors for atherosclerosis and in patients with established atherosclerotic disease. This defect parallels changes in vascular endothelial function and may be attributed to increased oxidative stress. Because atherosclerosis begins in childhood, we examined the correlates of nitrate-mediated dilatation (NMD) in children, including brachial artery endothelial function, oxidized LDL, and carotid artery intima-media thickness (IMT).

METHODS AND RESULTS

Brachial artery flow-mediated endothelium-dependent dilatation (FMD) and nitrate-mediated smooth muscle function, IMT of the carotid bulb, and brachial artery and oxidized LDL were measured in 142 children (mean age, 11 years; range, 8 to 17 years), including 87 healthy children, 41 diabetic children, and 14 children with familial hypercholesterolemia. NMD correlated directly with FMD (r=0.46, P<0.001) and inversely with brachial artery baseline diameter (r=-0.36, P<0.001), age (r=-0.25, P=0.003), body mass index (r=-0.31, P<0.001), diabetes (r=-0.22, P=0.008), oxidized LDL (r=-0.18, P=0.045), and IMT (r=-0.33, P<0.001). In a multivariate regression model, the significant correlates for NMD were FMD response (beta=0.003, P<0.001), brachial artery diameter (beta=-0.03, P=0.01), oxidized LDL (beta=-0.07, P=0.02), and IMT (beta=-0.15, P=0.03).

CONCLUSIONS

Reduced endothelial function, increased oxidative stress, and preclinical carotid atherosclerosis are independent determinants of impaired NMD in children. These data thus suggest that primary nitrate tolerance occurs in children at risk for atherosclerosis.

Folic acid improves endothelial function in children and adolescents with type 1 diabetes

OBJECTIVE

To evaluate the effect of folate supplementation on endothelial function in children and adolescents with type 1 diabetes.

STUDY DESIGN

Thirty-six subjects with type 1 diabetes age 13.6+/-2.6 years completed a randomized, double-blind, placebo-controlled crossover trial. Each subject received 8 weeks of oral folic acid (5 mg/d) and 8 weeks of placebo, with an 8-week washout period. Before and after each intervention, we assessed endothelial function by using brachial artery responses to flow (flow-mediated dilatation [FMD]) and glyceryl trinitrate, von Willebrand factor, glucose, hemoglobin A1c, total plasma homocyst(e)ine (tHcy), vitamin B(12), serum folate, and red cell folate (RCF).

RESULTS

Folic acid increased FMD by 2.58 (3.1-5.7) % (95% confidence interval, 1.28-3.88), whereas placebo did not change FMD (-0.42%; 95% confidence interval, -1.67 to 0.83; P<.001). Folic acid increased serum folate by 14 nmol/L (6.2 ng/mL, P<.001) and RCF by 467.2 nmol/L (206 ng/mL, P<.001). Change in FMD was related to change in serum folate (r=0.46, P=.005) and RCF (r=0.39, P=.02). Glyceryl trinitrate responses, von Willebrand factor, tHcy, and hemoglobin A1c were not affected by the intervention.

CONCLUSIONS

Short-term high-dose folic acid improves endothelial function in children and adolescents with type 1 diabetes and normal folate status independently of tHcy.

Endothelial dysfunction and increased arterial intima-media thickness in children with type 1 diabetes

BACKGROUND

Endothelial dysfunction may play a pathophysiological role in the development of atherosclerosis in subjects with type 1 diabetes. We examined whether alterations in vascular endothelial function exist in children with type 1 diabetes and tested the hypothesis that endothelial dysfunction is associated with early structural atherosclerotic vascular changes in these children.

METHODS AND RESULTS

Noninvasive ultrasound was used to measure brachial artery flow-mediated dilation (FMD) responses and carotid artery intima-media thickness (IMT) in 75 children (mean age 11+/-2 years), 45 with type 1 diabetes (diabetes duration 4.4+/-2.9 years) and 30 healthy control children. Children with diabetes had lower peak FMD response (4.4+/-3.4% versus 8.7+/-3.6%, P<0.001) and increased IMT (P<0.001) compared with controls. Sixteen children with diabetes (36%) had endothelial dysfunction defined as total FMD response in the lowest decile for normal children. These children had increased carotid IMT (0.58+/-0.05 versus 0.54+/-0.04 mm, P=0.01) and higher LDL cholesterol concentration (2.63+/-0.76 versus 2.16+/-0.60 mmol/L, P=0.03) compared with diabetic children without endothelial dysfunction. Multivariate correlates of increased IMT included diabetes group (P=0.03), low FMD (P=0.03), and high LDL cholesterol (P=0.08).

CONCLUSIONS

Impaired FMD response is a common manifestation in children with type 1 diabetes and is associated with increased carotid artery IMT. These data suggest that endothelial dysfunction in children with type 1 diabetes may predispose them to the development of early atherosclerosis.

Peripheral sympathetic control during dobutamine infusion

OBJECTIVES

We assessed the effects of beta-adrenergic agonism on muscle sympathetic nerve activity (MSNA) in patients with congestive heart failure (CHF) and young and matched controls.

BACKGROUND

Myocardial response to beta-adrenergic stimulation decreases with aging and with CHF.

METHODS

In CHF patients, we measured cardiac hemodynamics and MSNA (microneurography) before, with short-term (n = 5), and after 48-h (n = 9) of dobutamine infusion (10 microg/kg/min). In eight young controls and nine controls matched to the CHF patients, we measured cardiac hemodynamics and MSNA during randomized short-term dobutamine (10 microg/kg/min) and placebo infusions.

RESULTS

In CHF patients, short-term dobutamine infusion did not modify mean blood pressure (MBP), MSNA, or heart rate (HR). Moreover, 48-h dobutamine infusion increased cardiac index (3.1 +/- 0.2 vs. 2.2 +/- 0.2 l/min/m(2), p = 0.006), decreased mean pulmonary pressure (28 +/- 7 vs. 38 +/- 7 mm Hg, p = 0.0001) and peripheral resistance (1,099 +/- 112 vs. 1,759 +/- 263, p = 0.03), but did not change MBP, HR, or MSNA in the patients. In matched controls, dobutamine increased HR (87 +/- 5 vs. 65 +/- 2 beats/min, p = 0.0009) but did not change MBP or MSNA. In young controls, dobutamine increased MBP (102 +/- 2 vs. 90 +/- 2 mm Hg, p = 0.0003) and decreased MSNA (28 +/- 5 vs. 35 +/- 3 bursts/min, p = 0.03) but did not change HR (p = 0.054). In the controls, the largest increases in MBP with dobutamine were associated with the most marked reductions in MSNA (r = -0.49, p = 0.04) and the smallest increases in HR (r = -0.70, p = 0.001).

CONCLUSIONS

Arterial baroreceptor activation during increases in MBP inhibits MSNA and limits the HR response to dobutamine in controls. This mechanism, together with peripheral vasodilation, probably contributes to the absence of peripheral sympathetic withdrawal despite substantial hemodynamic improvements in CHF patients.

Antioxidant vitamins C and E improve endothelial function in children with hyperlipidemia: Endothelial Assessment of Risk from Lipids in Youth (EARLY) Trial

BACKGROUND

Hyperlipidemia is associated with endothelial dysfunction, an early event in atherosclerosis and predictor of risk for future coronary artery disease. Epidemiological studies suggest that increased dietary intake of antioxidants reduces the risk of coronary artery disease. The purpose of this study was to determine whether antioxidant vitamin therapy improves endothelial function and affects surrogate biomarkers for oxidative stress and inflammation in hyperlipidemic children.

METHODS AND RESULTS

In a randomized, double-blind, placebo-controlled trial, the effects of antioxidant vitamins C (500 mg/d) and E (400 IU/d) for 6 weeks and the National Cholesterol Education Program Step II (NCEP-II) diet for 6 months on endothelium-dependent flow-mediated dilation (FMD) of the brachial artery were examined in 15 children with familial hypercholesterolemia (FH) or the phenotype of familial combined hyperlipidemia (FCH). Antioxidant vitamin therapy improved FMD of the brachial artery compared with baseline (P<0.001) without an effect on biomarkers for oxidative stress (autoantibodies to epitopes of oxidized LDL, F2-isoprostanes, 8-hydroxy-2'-deoxyguanosine), inflammation (C-reactive protein), or levels of asymmetric dimethylarginine, an endogenous inhibitor of nitric oxide.

CONCLUSIONS

Antioxidant therapy with vitamins C and E restores endothelial function in hyperlipidemic children. Early detection and treatment of endothelial dysfunction in high-risk children may retard the progression of atherosclerosis.

Elevated serum C-reactive protein levels and early arterial changes in healthy children

OBJECTIVE

Elevated serum concentration of C-reactive protein (CRP) predicts cardiovascular events in adults. Because atherosclerosis begins in childhood, we undertook a study to determine whether changes in brachial artery endothelial function and the thickness of the carotid intima-media complex, 2 markers of early atherosclerosis, are related to CRP levels in healthy children.

METHODS AND RESULTS

Brachial artery flow-mediated dilatation (FMD) and carotid artery intima-media thickness (IMT) were measured with ultrasound in 79 children (aged 10.5+/-1.1 years). Compared with the children with CRP levels under the detection limit (<0.1 mg/L, n=40, group 1), the children with higher CRP (0.1 mg/L< or =CRP< or =0.7 mg/L, n=20, group 2; CRP >0.7 mg/L, n=19, group 3) had lower FMD (9.0+/-4.4% versus 7.8+/-3.3% versus 6.5+/-2.6%, respectively; P=0.015 for trend) and greater carotid IMT (0.45+/-0.03 versus 0.46+/-0.04 versus 0.49+/-0.06 mm, respectively, P=0.002 for trend). CRP level remained a statistically significant independent predictor for brachial FMD and carotid IMT in multivariate analyses.

CONCLUSIONS

These data suggest that CRP affects the arteries of healthy children by disturbing endothelial function and promoting intima-media thickening. The findings support the hypothesis that CRP plays a role in the pathogenesis of early atherosclerosis.