Effects of childhood primary hypertension on carotid intima media thickness: a matched controlled study

Different BMI cardiovascular risk thresholds as markers of organ damage and metabolic syndrome in primary hypertension

Obesity is the main intermediate phenotype of primary hypertension (PH), and increased fat mass is directly related to target organ damage (TOD) and metabolic syndrome (MS). The aim of the study was to assess the sensitivity and specificity of body mass index (BMI), percentile-based, definitions of obesity [BMI > 95th percentile (pc)], and overweight (BMI > 85th pc), and BMI thresholds for cardiovascular (cv) complications (BMIcv) described by Katzmarzyk et al. (Pediatrics 114:198-205, 2004) in predicting risk of TOD and MS in 122 adolescents with PH. Our results indicated that the prevalence of left ventricular hypertrophy (LVH) and carotid intima-media thickness (cIMT) above 2 standard deviations (SDS) was the same, irrespective of the criteria used. BMIcv was more sensitive as a marker of LVH than were the cut-off values of the 85th pc and 95th pc of BMI (87.5%, 75%, 62.5%, respectively; P < 0.0001). BMIcv thresholds and cut-off values of the 85th pc of BMI were of the same sensitivity in predicting the presence of MS (95.8% and 95.8%, respectively) and were more sensitive than the cut-off values of the BMI 95th pc (87.5%; P = 0.02). Metabolic abnormalities, including insulin resistance, were more marked in patients with greater BMI, irrespective of cut-off value. However, only when a stratification system using the 85th pc of BMI was used, were the differences significant for a homoeostasis model assessment for insulin resistance (HOMA-IR) and for serum concentrations of high-density lipoprotein (HDL)-cholesterol, triglycerides and adiponectin. We concluded that BMIcv is more sensitive for diagnosing the presence of LVH and that the cut-off value of the 85th pc of BMI is more sensitive for predicting presence of MS in children with PH.

Albumin excretion rate in normal adolescents: relation to insulin resistance and cardiovascular risk factors and comparisons to type 1 diabetes mellitus patients

BACKGROUND AND OBJECTIVES

Although albumin excretion rates have been related to cardiovascular morbidity and mortality in both diabetic and nondiabetic adults, little is known about the relation between albuminuria and either cardiovascular risk factors or the insulin resistance syndrome in adolescents. A normal range for albumin excretion in adolescents was established, correlations between albumin excretion and cardiovascular risk factors were evaluated, and albumin excretion in normal adolescents was compared with that in type 1 diabetes mellitus adolescents.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Albumin excretion rate was measured in 368 normal and 175 diabetic adolescents. Multiple regression analysis was used to predict the relation of age, sex, Tanner stage, body mass index, and systolic blood pressure to albumin excretion in both cohorts. In addition, correlations between albumin excretion and age, blood pressure, body mass index, lipids, and measurements of insulin resistance were performed in the normal adolescents.

RESULTS

Mean albumin excretion was significantly lower in normal adolescents (4.0 microg/min) than in type 1 diabetic adolescents (5.0 microg/min). Albumin excretion increased with age in diabetics. Albumin excretion did not significantly correlate with any measure of cardiovascular risk or insulin resistance but did significantly correlate with fasting insulin.

CONCLUSIONS

Albumin excretion rate is not related to insulin resistance or traditional cardiovascular risk factors in adolescence but is related to fasting insulin. Diabetic adolescents have increased albumin excretion compared with normal adolescents.

Increase in carotid intima-media thickness in grade I hypertensive subjects: white-coat versus sustained hypertension

We studied 74 never-treated grade I hypertensive subjects aged 18 to 45 years and 20 normotensive control subjects to define the rate of increase in carotid intima-media thickness (IMT) and the potential role played by the various risk factors. IMT was assessed as mean IMT and as maximum IMT in the right and left common carotid artery, carotid bulb, and internal carotid artery at baseline and at the 5-year follow-up. In grade I hypertensive subjects, both mean IMT and mean of maximum IMT were significantly higher compared with baseline values. Compared with normotensive subjects, both mean IMT and maximum IMT increased significantly (at least P<0.01) in each carotid artery segment. The increase in cumulative IMT was 3.4-fold for mean IMT and 3.2-fold for mean of maximum IMT. Levels of mean arterial pressure at 24-hour monitoring and total serum cholesterol were factors potentially linked to the increment in mean IMT and mean of maximum IMT. Age was also relevant for the increment in mean of maximum IMT, whereas body mass index played some role in the increment of mean IMT. During the follow-up, mean IMT and mean of maximum IMT increased to a greater degree in white-coat hypertensive subjects (n=35) and sustained hypertensive subjects (n=39) than in normotensive control subjects. No differences were found between white-coat hypertensive subjects and sustained hypertensive subjects for both mean IMT and maximum IMT. Levels of mean arterial pressure at 24-hour monitoring affected the increment in IMT in both white-coat hypertensive subjects and sustained hypertensive subjects. In conclusion, our findings indicate that carotid IMT is greater and grows faster in white-coat hypertensive subjects than in normotensive subjects without significant differences with sustained hypertensive patients.

Reproducibility of carotid intima-media thickness measurements in young adults

PURPOSE

To prospectively compare the reproducibility of carotid intima-media thickness (CIMT) measurements obtained from the right and left carotid arteries in young adults by using ultrasonographic (US) images acquired at the maximum dimension, minimum dimension, and electrocardiographically (ECG)-triggered cardiac end diastole.

MATERIALS AND METHODS

This study was HIPAA compliant and approved by the institutional review board; all participants provided informed consent. Medical history, anthropometric measurements, and blood pressure (BP) values were obtained from 50 men and 50 women aged 18-25 years. Images of the common carotid arteries were acquired from three independent complete cardiac cycles by using a 15L8-MHz US transducer. CIMT was measured on the images of each cycle that depicted the narrowest and widest vessel diameters, and at the R wave of the ECG. Measurements from the right and left carotid arteries were analyzed by using paired t tests; possible sex differences, by using unpaired t tests. Reproducibility was determined by using coefficients of variation and intraclass correlations (ICCs). Pearson correlations and multiple regression analyses were used to compare CIMT, body mass index (BMI), and BP.

RESULTS

CIMT values were 7.2% and 7% greater in frames showing the narrowest lumen diameter and in R-wave ECG-triggered frames, respectively, than in those with the widest diameter. CIMT measurements were 2.2%-3.1% greater in the right carotid artery than in the left (P < .001) and were significantly related to BMI (r = 0.40, P < .001) and systolic BP (r = 0.34, P < .001). ICCs were stronger when assessments were obtained in three different cardiac cycles (0.92-0.98), rather than in one (0.79-0.91).

CONCLUSION

In healthy young adults, reproducibility of CIMT measurements is greatest when combining values from both carotid arteries and/or from the maximal and minimal arterial diameters.

Controversies in vascular screening art versus science

Whether or not to screen asymptomatic members of the general public for various forms of vascular disease is a controversial issue with huge medical, social, and financial ramifications. This article reviews several criteria for determining the appropriateness of vascular screening, including: (1) is it possible to detect occult vascular disease ;early'?; (2) what should we screen for, and how should we do it?; (3) who should be screened?; and (4) what standards for vascular screening should be set? While some of these controversies may ultimately be resolvable using an evidence-based approach, it is apparent that there are issues which will not be amenable to strict scientific analysis. Individualized approaches to screening will therefore remain the rule for the foreseeable future.

Prevalence of hypertension in schoolchildren based on repeated measurements and association with overweight

OBJECTIVE

Most studies assess the prevalence of hypertension in pediatric populations based on blood pressure (BP) readings taken on a single visit. We determined the prevalence of hypertension measured on up to three visits in a Swiss pediatric population and examined the association between hypertension and overweight and selected other factors.

METHODS

Anthropometric data and BP were measured in all children of the sixth school grade of the Vaud canton (Switzerland) in 2005-2006. 'Elevated BP' was defined according to sex-specific, age-specific and height-specific US reference data. BP was measured on up to two additional visits in children with elevated BP. 'Hypertension' was defined as 'elevated BP' on all three visits.

RESULTS

Out of 6873 children, 5207 (76%) participated [2621 boys, 2586 girls; mean (SD) age, 12.3 (0.5) years]. The prevalence of elevated BP was 11.4, 3.8 and 2.2% on first, second and thirds visits, respectively; hence 2.2% had hypertension. Among hypertensive children, 81% had isolated systolic hypertension. Hypertension was associated with excess body weight, elevated heart rate and parents' history of hypertension. Of the children, 16.1% of boys and 12.4% of girls were overweight or obese (CDC criteria, body mass index >or= 85th percentile). Thirty-seven percent of cases of hypertension could be attributed to overweight or obesity.

CONCLUSIONS

The proportion of children with elevated BP based on one visit was five times higher than based on three measurements taken at few-week intervals. Our data re-emphasize the need for prevention and control of overweight in children to curb the global hypertension burden.

Ambulatory blood pressure monitoring and target organ damage in pediatrics

The prevalence of hypertension in children and adolescents is rising in association with the increasing rate of childhood obesity, and it is associated with early target organ damage. Published guidelines on high blood pressure in children and adolescents, focused on the early and accurate diagnosis of hypertension, resulted in improved ability to identify children with hypertension. Although auscultation using a mercury sphygmomanometer remains the method of choice for evaluation of hypertension in children, accumulating evidence suggests that ambulatory blood pressure monitoring is a more accurate method for diagnosis, and it is more closely associated with target organ damage. In addition, ambulatory blood pressure monitoring is a valuable tool in the assessment of white-coat hypertension, and masked hypertension in children and adolescents. Masked hypertension in children and adolescents is associated with a similar risk of target organ damage as in established hypertension.

Ability of blood pressure to predict left ventricular hypertrophy in children with primary hypertension

OBJECTIVE

To determine whether casual blood pressure (BP) or ambulatory BP monitoring (ABPM) measurements obtained at the initial visit of a child with confirmed hypertension (HTN) might predict left ventricular hypertrophy (LVH), possibly obviating the need for echocardiography.

STUDY DESIGN

We conducted a cross-sectional study of 184 children aged 3 to 20 years who were referred for initial evaluation of elevated BP at 3 tertiary care centers. Casual BP and various ambulatory BP variables were analyzed to determine their association with LVH, defined after echocardiography by cardiologist diagnosis or a left ventricular mass index equal to or greater than the sex-specific 95th percentile.

RESULTS

A total of 41% of children who had echocardiograms had LVH. Children with LVH were significantly more likely to be non-white and have a higher body mass index z-score. There was no difference in casual systolic or diastolic BP index in children with hypertension who had LVH and children with hypertension without LVH. Children with systolic or diastolic BP loads > or = 50% were no more likely to have LVH than children with loads < 50%.

CONCLUSION

LVH is common in children with newly diagnosed HTN. The initial examination of these children should include echocardiography, because neither the severity of casual BP elevation nor the presence of abnormal ambulatory BP results at initial diagnosis are predictive of LVH.

Metabolic risk-factor clustering estimation in children: to draw a line across pediatric metabolic syndrome

BACKGROUND

The diagnostic criteria of the metabolic syndrome (MS) have been applied in studies of obese adults to estimate the metabolic risk-associated with obesity, even though no general consensus exists concerning its definition and clinical value. We reviewed the current literature on the MS, focusing on those studies that used the MS diagnostic criteria to analyze children, and we observed extreme heterogeneity for the sets of variables and cutoff values chosen.

OBJECTIVES

To discuss concerns regarding the use of the existing definition of the MS (as defined in adults) in children and adolescents, analyzing the scientific evidence needed to detect a clustering of cardiovascular risk-factors. Finally, we propose a new methodological approach for estimating metabolic risk-factor clustering in children and adolescents.

RESULTS

Major concerns were the lack of information on the background derived from a child's family and personal history; the lack of consensus on insulin levels, lipid parameters, markers of inflammation or steato-hepatitis; the lack of an additive relevant effect of the MS definition to obesity per se. We propose the adoption of 10 evidence-based items from which to quantify metabolic risk-factor clustering, collected in a multilevel Metabolic Individual Risk-factor And CLustering Estimation (MIRACLE) approach, and thus avoiding the use of the current MS term in children.

CONCLUSION

Pediatricians should consider a novel and specific approach to assessing children/adolescents and should not simply derive or adapt definitions from adults. Evaluation of insulin and lipid levels should be included only when specific references for the relation of age, gender, pubertal status and ethnic origin to health risk become available. This new approach could be useful for improving the overall quality of patient evaluation and for optimizing the use of the limited resources available facing to the obesity epidemic.

C-reactive protein and incident left ventricular hypertrophy in essential hypertension

Elevated C-reactive protein (CRP) levels have been associated with increased cardiovascular risk in hypertensive adults. The aim of this study was to determine whether plasma CRP level is more predictive of left ventricular hypertrophy (LVH) than is ambulatory blood pressure (BP) in hypertensive children. Baseline and 12-month follow-up measures of BP, body mass index (BMI), low-density lipoprotein/high density lipoprotein cholesterol, left ventricular mass (LVM), and CRP data collected from 48 newly diagnosed, untreated hypertensive children were analyzed. CRP was measured by a highly sensitive nephelometric method. Left ventricular mass index (LVMI) was calculated as LVM/height2.7, and LVH was defined as LVMI>38.6 g/m2.7 being the cut-point for the 95th percentile found in healthy children. Average systolic BP (SBP), diastolic BP (DBP), SBP index, and DBP index were calculated. All patients received hydrochlorothiazide therapy in combination with angiotensin converting enzyme inhibitor treatment. Five patients also had angiotensin receptor blocker therapy to reach the target BP (<95th percentile corrected for age and gender). In a multiple regression analysis, LMVI was correlated with CRP, BMI, SBP, and SBP index. CRP alone explained 77% of the variance of LVMI, whereas BMI, SBP, and SBP index explained only 1.3, 0.3, and 0.4% of the variance, respectively. CRP was also the most significant correlate of follow-up LVH. In conclusion, elevated CRP level is significantly associated with LVH in children with essential hypertension. BP reduction with renin-angiotensin system blocker and hydrochlorothiazide therapy reduces LVH while lowering CRP level.

Evaluation of hypertension by the general pediatrician

PURPOSE OF REVIEW

To summarize the recommended work-up in a child who presents with elevated blood pressure as well as innovative evaluation techniques under development.

RECENT FINDINGS

'The fourth report on the diagnosis, evaluation, and treatment of high blood pressure in children and adolescents' contains several updates on the diagnosis, evaluation and treatment of childhood hypertension. New risk factors for hypertension have been identified and include obesity, sleep apnea, and low birth weight. The roles of uric acid, leptin and C-reactive protein in the pathophysiology of hypertension have been examined. The presence of hypertensive end-organ damage has been demonstrated in hypertensive children.

SUMMARY

Current knowledge emphasizes the need to diagnose and treat hypertension when it develops in childhood to decrease the risk of cardiovascular morbidity in adulthood. End-organ injury is evident, illustrated by the presence of left ventricular hypertrophy, even in young children. Assessment for the presence of comorbidities and end-organ damage should be emphasized. Further study is needed to isolate the etiologic factors for childhood hypertension, improve evaluation techniques, and determine if end-organ damage is reversible with proper therapy.

Prevalence of elevated blood pressure and association with overweight in children of a rapidly developing country

We assessed the prevalence of elevated blood pressure (BP) and the association with excess body weight among a large sample of children in the Seychelles, a middle-income rapidly developing country in the African region. Weight, height and BP were measured in all children of four school grades in the Seychelles (Indian Ocean). Excess weight categories ('overweight' and 'obesity') were defined according to the criteria of the International Obesity Task Force. Two BP readings were obtained on one occasion. 'Elevated BP' was defined based on US reference tables. Data were available in 15,612 (86%) of 18,119 eligible children aged 5-16 years in 2002-2004. In all, 13.0% of Boys and 18.8% of girls were overweight or obese. The prevalence of elevated BP was 9.1% in boys and 10.1% in girls. Both systolic and diastolic BP were strongly associated with body mass index (BMI) in boys and in girls. In children with 'normal weight', 'overweight (and not obesity)' and 'obesity', respectively, proportions with elevated BP were 7.5, 16.9 and 25.2% in boys, and 7.5, 16.1 and 33.2% in girls. Overweight (including obesity) could account for 18% of cases of elevated BP in boys and 26% in girls. Further studies should examine the impact of the relationship between BMI and elevated BP on the burden of hypertension in the context of the epidemic of paediatric obesity.

Hypertension in children

Essential, or primary, hypertension is detectable in childhood. Due to the rising rates of childhood obesity, the expression of essential hypertension in childhood is increasing. Despite this trend, the possibility of secondary hypertension should be considered in a child with documented hypertension. Children and adolescents with suspected secondary hypertension may require a more extensive evaluation compared with those expressing characteristics of essential hypertension. Whether the hypertension is determined to be secondary or essential, these children require careful monitoring, interventions to control the blood pressure, and long-term follow-up. Considering the long-term morbidity and mortality associated with essential hypertension, interventions, including preventive interventions, that focus on blood pressure control beginning in the young are an important component of healthcare for children and adolescents.