Ambulatory blood pressure monitoring in childhood and adult obesity

Cardiovascular rhythmicity in overweight and obese children

INTRODUCTION

Obesity is thought to play a role in the disruption of cardiac rhythmicity in obese children, but this is mostly an unexplored field of investigation. We aimed to evaluate the impact of overweight and obesity on circadian and ultradian cardiovascular rhythmicity of prepubertal children, in comparison with normal weight counterparts.

METHODS

We performed a cross sectional study of 316 children, followed in the birth cohort Generation XXI (Portugal). Anthropometrics and 24-hour ambulatory blood pressure were measured and profiles were examined with Fourier analysis for circadian and ultradian blood pressure (BP) and heart rate (HR) rhythms.

RESULTS

Overweight/obese children presented more frequently a non-dipping BP pattern than normal weight counterparts (31.5% vs. 21.6%, p = 0.047). The prevalence of 24-hour mean arterial pressure (MAP) and 8-hour HR rhythmicity was significantly lower in obese children (79.3% vs. 88.0%, p = 0.038 and 33.3% vs. 45.2%, p = 0.031, respectively). The prevalence of the remaining MAP and HR rhythmicity was similar in both groups. No differences were found in the median values of amplitudes and acrophases of MAP and HR rhythms.

DISCUSSION

The alterations found in rhythmicity suggest that circadian and ultradian rhythmicity analysis might be sensitive in detecting early cardiovascular dysregulations, but future studies are needed to reinforce our findings and to better understand their long-term implications.

Hemoglobin A1c and C-reactive protein are independently associated with blunted nocturnal blood pressure dipping in obesity-related prediabetes

Blunted nocturnal dipping in blood pressure (BP) is associated with increased cardiovascular disease (CVD) risk in middle-aged/older adults. The prevalence of blunted nocturnal BP dipping is higher in persons with obesity and diabetes, conditions that are also associated with elevated aortic stiffness and inflammation. Therefore, we hypothesized that elevated glycemia, inflammation and aortic stiffness would be inversely associated with the magnitude of nocturnal systolic BP dipping among middle-aged/older adults with obesity at high CVD risk. Twenty-four hour ambulatory BP monitoring, aortic stiffness (carotid-femoral pulse wave velocity, CF-PWV), hemoglobin A1c (HbA1c) and inflammation (C-reactive protein, CRP) were measured in 86 middle-aged/older adults with obesity and at least one other CVD risk factor (age 40-74 years; 34 male/52 female; body mass index=36.7±0.5 kg m^-2; HbA1c=5.7±0.04%). In the entire cohort, CRP (β=0.40±0.20, P=0.04), but not HbA1c or CF-PWV was independently associated with systolic BP dipping percent (Model R²=0.07, P=0.12). In stratified (that is, presence or absence of prediabetes) multiple linear regression analysis, HbA1c (β=6.24±2.6, P=0.02) and CRP (β=0.57±0.2, P=0.01), but not CF-PWV (β=0.14± 2.6, P=0.74), were independently associated with systolic BP dipping percent (Model R²=0.32, P<0.01) in obese adults with prediabetes but were absent in obese adults without prediabetes (Model R²=0.01 P=0.95). However, nocturnal systolic BP dipping percent (P=0.65), CF-PWV (P=0.68) and CRP (P=0.59) were similar between participants with and without prediabetes. These data suggest that impaired long-term glycemic control and higher inflammation may contribute partly to blunted BP dipping in middle-aged/older adults with obesity-related prediabetes.

Association of myeloperoxidase levels with cardiometabolic factors and renal function in prepubertal children

INTRODUCTION

Myeloperoxidase (MPO), an enzyme linking obesity and cardiovascular (CV) risk in adults, has rarely been studied in young children and no studies assessed its association with renal function. We sought to explore a possible association between serum MPO levels, obesity, CV risk factors and renal function in prepubertal children.

MATERIALS/METHODS

Cross-sectional evaluation of 309 children aged 8-9 years (161 normal weight, 148 overweight/obese), members of the birth cohort Generation I (Portugal). Anthropometrics (body mass index (BMI), waist-to-height ratio (WHtR) and % body fat mass (%BFM) by bioelectrical impedance analysis), 24-h ambulatory blood pressure monitoring and pulse wave velocity (PWV) were measured. Insulin resistance was estimated by the HOMA index (considering serum fasting glucose and insulin determinations). Serum MPO levels were assessed by immunoenzymatic assay.

RESULTS

MPO levels were positively associated with obesity indices (BMI z-score, WHtR and %BFM). Higher MPO levels were associated with higher 24-h and night-time mean arterial pressure, with nondipping and with higher values of insulin resistance. In normal weight children, the endothelial function, as evaluated indirectly by PWV, was an independent predictor of MPO levels. In overweight/obese children, estimated glomerular filtration rate increased significantly across tertiles of MPO (Ptrend = 0·031) and this association held after adjustment for age, sex, neutrophil and monocyte counts and CV risk factors.

CONCLUSIONS

Our results reinforce the role of MPO as a risk marker in obesity and related CV morbidities in young children. MPO levels associate with the dipping pattern and PWV and, among overweight/obese children, an association exists between MPO and renal function.

Is Daytime Systolic Load an Important Risk Factor for Target Organ Damage in Pediatric Hypertension?

The aim of this study was to compare ambulatory blood pressure (BP) monitoring (ABPM) data and determine which hypertension type is a risk factor in target organ damage. A total of 82 children (47 boys) with suspected hypertension based on office BP measurements and considered hypertensive by ABPM were studied. Target organ damage included the following: 35.3% hypertensive retinopathy, 25.6% microalbuminuria, 15.8% increased left ventricular mass index, 29.2% increased carotid intima-media thickness (cIMT), 24.3% high augmentation index (AIx), and 19.5% high pulse wave velocity (PWV). The association between BP load, PWV, and cIMT was statistically significant. There were significant correlations between daytime systolic BP load, PWV, AIx, and cIMT. A statistically significant difference was also detected between nighttime systolic BP load, PWV, and cIMT values and nighttime diastolic BP load levels and values of AIx and cIMT. There was also a statistically significant difference between the high level of nighttime diastolic BP load and cIMT. The authors found that target organ damage was seen more often in children with primary hypertension who had systolic loads.