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

Prevalence of left ventricular hypertrophy in children and young people with primary hypertension: Meta-analysis and meta-regression

BACKGROUND

Left ventricular hypertrophy (LVH) is the main marker of HMOD in children and young people (CYP). We aimed to assess the prevalence of LVH and its determinants in CYP with primary hypertension (PH).

METHODS

A meta-analysis of prevalence was performed. A literature search of articles reporting LVH in CYP with PH was conducted in Medline, Embase, and Cochrane databases. Studies with a primary focus on CYP (up to 21 years) with PH were included. Meta-regression was used to analyze factors explaining observed heterogeneity.

RESULTS

The search yielded a total of 2,200 articles, 153 of those underwent full-text review, and 47 reports were included. The reports evaluated 51 study cohorts including 5,622 individuals, 73% male subjects, and a mean age of 13.6 years. LVH was defined as left ventricle mass index (LVMI) ≥ 95th percentile in 22 (47%), fixed cut-off ≥38.6 g/m2.7 in eight (17%), sex-specific fixed cut-off values in six (13%), and miscellaneously in others. The overall prevalence of LVH was 30.5% (95% CI 27.2-33.9), while heterogeneity was high (I 2 = 84%). Subgroup analysis including 1,393 individuals (76% male subjects, mean age 14.7 years) from pediatric hypertension specialty clinics and LVH defined as LVMI ≥95th percentile only (19 study cohorts from 18 studies), reported prevalence of LVH at 29.9% (95% CI 23.9 to 36.3), and high heterogeneity (I 2 = 84%). Two studies involving patients identified through community screening (n = 1,234) reported lower LVH prevalence (21.5%). In the meta-regression, only body mass index (BMI) z-score was significantly associated with LVH prevalence (estimate 0.23, 95% CI 0.08-0.39, p = 0.004) and accounted for 41% of observed heterogeneity, but not age, male percentage, BMI, or waist circumference z-score. The predominant LVH phenotype was eccentric LVH in patients from specialty clinics (prevalence of 22% in seven studies with 779 participants) and one community screening study reported the predominance of concentric LVH (12%).

CONCLUSION

Left ventricular hypertrophy is evident in at least one-fifth of children and young adults with PH and in nearly a third of those referred to specialty clinics with a predominant eccentric LVH pattern in the latter. Increased BMI is the most significant risk association for LVH in hypertensive youth.

The Relationship between the Waist Circumference and Increased Carotid Intima Thickness in Obese Children

Background: This study aimed to evaluate the cardiometabolic risk factors in normotensive obese and hypertensive obese (HT-obese) children by comparison of anthropomorphic measurements, fat distribution, carotid artery intima-media thickness (CIMT), and inflammatory markers. Methods: Fifty-three obese patients 10-18 years of age with a BMI-for-age/gender >95th percentile and 20 age- and gender-matched healthy volunteers enrolled in the study. Obese patients were divided into two groups according to the presence of hypertension (HT), as follows: HT-obese subgroup (n = 30) and nonhypertensive obese (non-HT-obese) subgroup (n = 23). Results: Weight standard deviation score (SDS), BMI-SDS, waist circumference (WC) SDS, and the fat tissue z-score were significantly higher (p < 0.001 for all) in the obese patients than the control groups. Obese patients had higher 24-hour systolic blood pressure (SBP) SDS and leptin, high-sensitivity C-reactive protein, tumor necrosis factor-alpha, and interleukin-6 levels. Furthermore, CIMT and CIMT-SDS were significantly higher in them. HT-obese patients (n = 30) had significantly higher WC-SDS and lower serum leptin and adiponectin levels than those of non-HT-obese group (n = 23). Finally, an association between increased CIMT-SDS and WC-SDS (β = 0.399, p = 0.002) and 24-hour SBP-SDS (β = 0.272, p = 0.009) was shown. Conclusions: Association between increased WC and HT implies the importance of central obesity in atherosclerosis. We concluded that WC measurement could be used to define risk groups since it is related to cardiometabolic complications.

Autonomic nervous system dysregulation in pediatric hypertension

Historically, primary hypertension (HTN) has been prevalent typically in adults. Recent data however, suggests an increasing number of children diagnosed with primary HTN, mainly in the setting of obesity. One of the factors considered in the etiology of HTN is the autonomous nervous system, namely its dysregulation. In the past, the sympathetic nervous system (SNS) was regarded as a system engaged mostly in buffering major acute changes in blood pressure (BP), in response to physical and emotional stressors. Recent evidence suggests that the SNS plays a much broader role in the regulation of BP, including the development and maintenance of sustained HTN by a chronically elevated central sympathetic tone in adults and children with central/visceral obesity. Consequently, attempts have been made to reduce the SNS hyperactivity, in order to intervene early in the course of the disease and prevent HTN-related complications later in life.

Subclinical atherosclerosis and ambulatory blood pressure in children with metabolic syndrome

BACKGROUND

The metabolic syndrome (MS) has reached epidemic proportions worldwide. This syndrome is associated with cardiovascular risk factors, including functional and structural cardiac and vascular changes. The aim of our study was to evaluate subclinical atherosclerosis and its associated risk factors in children with MS.

METHODS

The study cohort comprised 52 children with MS and 38 age- and sex-matched healthy children. The diagnosis of MS was made according to criteria adopted by the World Health Organization. Blood pressure based on 24-h ambulatory blood pressure monitoring (ABPM), carotid intima-media thickness (cIMT), carotid distensibility coefficient (DC) and flow-mediated endothelium-dependent dilation (EDD) were assessed in all children.

RESULTS

We found a significantly higher cIMT in children with MS than in healthy children, but carotid DC and flow-mediated EDD were lower in the former. Multivariate analysis revealed that a higher cIMT was independently associated with a higher nighttime systolic blood pressure (SBP) and lower high-density lipoprotein-cholesterol (β = 0.386, p = 0.011 and β = 0.248, p = 0.042, respectively). Also, higher nighttime SBP remained an independent predictor of lower DC (β = 0.495, p = 0.009), and higher 24-h SBP was the only independent predictor for a lower EDD (β = 0.532, p = 0.004).

CONCLUSIONS

Atherosclerotic vascular changes were common among our pediatric patients with MS and easily determined by high-resolution ultrasound imaging. In particular, subclinical atherosclerosis was clearly associated with nocturnal or 24-h systolic hypertension as measured by ABPM. We therefore recommend that subclinical vascular changes and AMBP measurements should be used as diagnostic markers to predict atherosclerotic risks in this pediatric patient group.

Associations of cardiac structure with obesity, blood pressure, inflammation, and insulin resistance in African-American adolescents

To determine if obesity, blood pressure (BP), markers of inflammation, and insulin resistance are associated with cardiac structure in African-American adolescents, a cross-sectional study was performed on a cohort oversampled for high BP and obesity. Measurements included the following: anthropometrics, BP, homeostasis model assessment (HOMA) to assess insulin resistance, high-sensitivity C-reactive protein, and plasma adipokines (adiponectin, interleukin-6, plasminogen activator inhibitor-1). Echocardiogram measurements were left-ventricular mass index (LVMI) (g/m(2.7)), LV relative wall thickness (LVRWT), left-atrial diameter index [LADI (mm/m)], and LV diastolic time intervals. LADI (r (2) = 0.25) was associated with body mass index (BMI) systolic BP (SBP) and female sex. LVMI (r (2) = 0.35) variation was associated with BMI SBP, heart rate, age, and male sex. LVRWT (r (2) = 0.05) was associated with HOMA. Tissue diastolic intervals were not associated with any risk factor. Inflammatory markers and adipokines were associated with BMI but were not independently associated with any echocardiographic measures. In African-American adolescents, BMI and SBP, but not inflammatory markers or adipokines, are important correlates of LA size and LVM.

The prodromal phase of obesity-related chronic kidney disease: early alterations in cardiovascular and renal function in obese children and adolescents

Childhood overweight and obesity is a relevant health condition with multi-organ involvement. Obesity shows significant tracking into adult life and is associated with an increased risk of serious adverse health outcomes both during childhood and later adulthood. The classical sequelae of obesity such as hypertension, metabolic syndrome and inflammation do develop at a paediatric age. Cardiovascular consequences, such as increased carotid intima-media thickness, and left ventricular hypertrophy, as well as functional alterations of the heart and arteries, are commonly traceable at an early age. Renal involvement can occur at a young age and is associated with a high probability of progressive chronic kidney disease. There is solid evidence suggesting that consequent treatment including both lifestyle changes and pharmacological therapy can reduce cardiovascular, metabolic and renal risks in obese children and adolescents.

Primary hypertension in children and adolescents is an immuno-metabolic disease with hemodynamic consequences

With the rise in obesity epidemic primary hypertension (PH) is now one of the most common chronic diseases in adolescence. In contrast to hypertensive adults, hypertensive children usually are not exposed to other comorbidities such as diabetes, chronic kidney disease and atherosclerosis. Thus, PH in children and adolescents can be treated as the early stage of development of cardiovascular disease. There is increasing amount of data indicating that PH is not only hemodynamic phenomenon but a complex syndrome involving disturbed activity of sympathetic nervous system, metabolic abnormalities and activation of innate and adaptive immune system. We discuss results of the studies on clinical, metabolic and immunological phenotype of hypertensive children, associations between metabolic and immunological abnormalities with target organ damage and results of antihypertensive treatment.

Carotid artery intima-media thickness and distensibility in children and adolescents: reference values and role of body dimensions

Carotid intima-media thickness (cIMT) and carotid artery distensibility are reliable screening methods for vascular alterations and the assessment of cardiovascular risk in adult and pediatric cohorts. We sought to establish an international reference data set for the childhood and adolescence period and explore the impact of developmental changes in body dimensions and blood pressure (BP) on carotid wall thickness and elasticity. cIMT, the distensibility coefficient, the incremental modulus of elasticity, and the stiffness index β were assessed in 1155 children aged 6 to 18 years and sex-specific reference charts normalized to age or height were constructed from 1051 nonobese and nonhypertensive children. The role of body dimensions, BP, and family history, as well as the association between cIMT and distensibility, was investigated. cIMT increased and distensibility decreased with age, height, body mass index, and BP. A significant sex difference was apparent from the age of 15 years. Age- and height-normalized cIMT and distensibility values differed in children who are short or tall for their age. By stepwise multivariate analysis, standardized systolic BP and body mass index were independently positively associated with cIMT SD scores (SDS). Systolic BP SDS independently predicted all distensibility measures. Distensibility coefficient SDS was negatively and β SDS positively associated with cIMT SDS, whereas incremental modulus of elasticity was independent of cIMT. Morphological and functional aspects of the common carotid artery are particularly influenced by age, body dimensions, and BP. The reference charts established in this study allow to accurately compare vascular phenotypes of children with chronic conditions with those of healthy children.

Health impact in children and adolescents

Obesity in children and adolescents is associated with multiple comorbidities, including metabolic, cardiovascular, gastrointestinal, pulmonary, orthopedic and psychological disorders. In fact, cardiovascular and metabolic impairments in childhood and adolescence constitute major risk factors for developing cardiovascular disease in adulthood. Thus, obesity in childhood and adolescence leads to a higher morbidity and mortality in adulthood. Therefore, strong emphasis must be laid on the prevention and therapy of childhood obesity. Treatment requires a multidisciplinary and multiphase approach including dietary management, physical activity, pharmacotherapy and bariatric surgery. This paper reviews the different comorbidities of childhood obesity supporting the notion of a multidisciplinary therapy concept.

Adiponectin and hypertension in normal-weight and obese children

BACKGROUND

Adiponectin (AD) reduces the risk of hypertension because of its anti-inflammatory, antiatherogenic, and insulin-sensitizing properties. The study described here was done to evaluate the interrelationships of AD, blood pressure (BP), obesity, body-fat distribution, puberty, and insulin resistance in a selected group of children.

METHODS

The study was a cross-sectional, observational study of 186 children ranging in age from 5-18 years and grouped according to weight class (obese (OB), n = 100; normal weight (NW), n = 86) and BP category (hypertensive (HT) n = 79; normotensive (NT); n = 107). The children were also classified on the basis of fat distribution (waist circumference/height ratio). Their blood glucose, insulin, and AD concentrations were assayed, and their homeostatic model assessment (HOMA) index was calculated as an estimate of insulin resistance.

RESULTS

Serum AD was lower in OB-HT (7,111±4,163ng/ml) than in NW-NT (12,622±6,276ng/ml) children (P < 0.0001). Intermediate values of AD were found in OB-NT (9,099±3,988ng/ml) and NW-HT (9,808±4,211ng/ml) children. Weight and waist circumference-to-height ratio, BP category, and pubertal stage were all independently and inversely associated with serum levels of AD (P < 0.02). In a logistic regression model, after adjustment for body mass index (BMI) and waist circumference/height ratio, serum levels of AD maintained an independent association with hypertension (P < 0.05), as did also the HOMA index (P < 0.05). A reduction of 10 times (i.e., one unit on the log(10) scale) in AD serum levels was associated with a 50% increased probability of having hypertension.

CONCLUSIONS

In childhood, serum levels of AD are inversely related to hypertension. This relationship is partly independent of obesity, fat distribution, and insulin resistance. Low values of AD in both OB and NW children are associated with a higher probability of hypertension.

Ambulatory blood pressure monitoring and cardiac hypertrophy in children with metabolic syndrome

BACKGROUND

The metabolic syndrome (MS), a cluster of potent risk factors for cardiovascular disease, is composed of insulin resistance, obesity, hypertension and hyperlipidemia. The aim of our study was to investigated the relationships between MS and left ventricular mass index (LVMI) in childhood MS. This study included 50 children and adolescents with MS aged between 7-18 years.

METHODS

Thirty age- and sex-matched healthy children served as a control group. The diagnosis of MS was made according to the criteria adapted from the World Health Organization. They underwent clinical examination with causal blood pressure (BP) measurements, 24-hour ambulatory blood pressure monitoring (ABPM) and echocardiogram. Patients underwent echocardiography to detect left ventricular hypertrophy (LVH). LVMI was calculated as left ventricular mass/height(2.7).

RESULTS

The mean age of MS group was 12.0 ± 3.1 years. The mean value of LVMI was 46.5 ± 11.5 g/m(2.7) in the MS group and it was significantly higher than those in the healthy children. The prevalence of severe LVH was 12 % using adult criteria (LVM > 51 g/m(2.7)) and 44 % using pediatric criteria (LVM > 95th percentile). The mean daytime systolic BP load (β = 0.315, p = 0.003) and HOMA-IR (β = 0.368, p = 0.006) were found as the independent predictors of LVMI.

CONCLUSIONS

In conclusion, LVH occurs commonly in pediatric MS and is associated with systolic hypertension and insulin resistance. LVMI should be measured routinely for the predicting of cardiovascular risks in these patients.

Left ventricular mass in normotensive, prehypertensive and hypertensive children and adolescents

The purpose of this study was to investigate differences in left ventricular mass index (LVMI) and the prevalence of left ventricular hypertrophy (LVH) in children and adolescents classified as normotensives, prehypertensives and hypertensives by ambulatory blood pressure (BP) levels. A total of 124 consecutive children and adolescents aged 5 to 18 years were analysed. Patients underwent 24 h ambulatory blood pressure monitoring (ABPM) and echocardiography. Hypertensive and prehypertensive subjects had significantly higher LVMI than normotensives (36.8 +/- 8.4 g/m(2.7) and 34.1 +/- 3.4 g/m(2.7) vs. 29.5 +/- 8.3 g/m(2.7), P < 0.01 and P < 0.05, respectively). In multivariate analysis predictors for LVMI were body mass index (BMI) z score and hypertension (R-squared = 0.31). LVMI values in hypertensive subjects were significantly higher than those of normotensives even after adjustment for age, sex and BMI z score. The prevalence of LVH was significantly higher in the prehypertensive compared to normotensive subjects, and was equal to that of the hypertensive subjects. Hypertension and prehypertension in children and adolescents were associated with pathologically elevated LVMI values. If confirmed in a larger group prehypertensive children may be at risk for target organ damage similar to the condition of established hypertension.

Intima-media thickness measurements in children with cardiovascular risk factors

Measuring intima-media thickness (IMT) is now a standard diagnostic procedure in assessing cardiovascular risk and hypertensive target-organ damage (TOD) in adults. There is also an increasing number of pediatric publications evaluating IMT in children from high-risk groups, such as those with arterial hypertension, diabetes, chronic kidney disease, obesity, dyslipidemia, and homocystinurias. It has been shown that carotid IMT is strongly related with other markers of TOD in children with arterial hypertension and with metabolic cardiovascular risk factors. In children with coarctation of the aorta, carotid IMT correlated both with blood pressure and even with mild residual aortic gradient. On the other hand, studies in children with high cardiovascular risk have shown that normalization of blood pressure and metabolic abnormalities led to regression of arterial changes and decrease of IMT. Although not yet accepted as standard pediatric procedure, IMT measurement is emerging as a promising method of assessing TOD and cardiovascular risk and monitoring treatment efficacy. From a practical point of view, clinical utility of IMT measurements seems to be similar to use of echocardiography in assessing left ventricular mass. However, IMT measurements in children and adolescents should be standardized to avoid bias caused by the use of different measurement methods.