Cardiac autonomic dysfunction in obese normotensive children and adolescents

Abstract

OBJECTIVE:To test the hypothesis that obese normotensive children and adolescents present impaired cardiac autonomic control compared to non-obese normotensive ones. METHODS:For this cross-sectional study, 66 children and adolescents were divided into the following groups: Obese (n=31, 12±3 years old) and Non-Obese (n=35, 13±3 years old). Obesity was defined as body mass index greater than the 95th percentile for age and gender. Blood pressure was measured by oscillometric method after 15 minutes of rest in supine position. The heart rate was continuously registered during ten minutes in the supine position with spontaneous breathing. The cardiac autonomic control was assessed by heart rate variability, which was calculated from the five-minute minor variance of the signal. The derivations were the index that indicates the proportion of the number of times in which normal adjacent R-R intervals present differences >50 miliseconds (pNN50), for the time domain, and, for the spectral analysis, low (LF) and high frequency (HF) bands, besides the low and high frequencies ratio (LF/HF). The results were expressed as mean±standard deviation and compared by Student's t-test or Mann-Whitney's U-test. RESULTS: Systolic blood pressure (116±14 versus 114±13mmHg, p=0.693) and diastolic blood pressure (59±8 versus 60±11mmHg, p=0.458) were similar between the Obese and Non-Obese groups. The pNN50 index (29±21 versus 43±23, p=0.015) and HF band (54±20 versus 64±14 normalized units - n.u., p=0.023) were lower in the Obese Group. The LF band (46±20 versus 36±14 n.u., p=0.023) and LF/HF ratio (1.3±1.6 versus 0.7±0.4, p=0.044) were higher in Obese Group. CONCLUSIONS: Obese normotensive children and adolescents present impairment of cardiac autonomic control.

Autonomic Nervous System Derangement as a Predictor of Cardiovascular Disease in Obese Postmenopausal Women

“…16 In this study, an increase in anthropometric parameters such as body fat percentage, waist and hip circumferences, and WHR were observed with increasing BMI in obese patients, which is consistent with previous studies. [16][17][18][19][20] In our study, we also observed that the SBP and DBP were higher in obese women than in the nonobese, which is consistent with other studies done previously. 21,22 Heart rate variability is less in obese individuals as obesity is associated with marked sympathetic activation and reduced parasympathetic activation.…”

Cardiac Autonomic Function at Baseline and under Stress and Its Relationship to Circulatory Markers of Inflammation in Obese Compared to Nonobese Children: A Pilot Study

“…Firstly, it is possible that our obese subjects may differ in aspects of their disease compared to subjects in other studies. Indeed, compared to prior childhood obesity HRV studies, a striking difference with our cohort is that all but two of the prior studies that included blood pressure measurements documented significantly higher levels of blood pressure in the obese group [9,23,24,25,27,29,31,34,35,36]. In our study, however, despite dramatic differences in BMI between groups, subjects in both groups had normal median resting blood pressures and heart rates.…”

“…To first address the autonomic testing, in a well-characterized cohort, we detected no ANS difference between obese and nonobese children. A review of published studies regarding HRV in childhood obesity indicates that the most common findings include increased SNS and decreased PNS tone; however, there is considerable variability in HRV results, study quality, and methodology [9,15,23,24,25,26,27,28,29,30,31,32,33,34,35,36]. In previous pediatric studies using similar HRV measures, the most common finding was decreased HF (natural log, raw, or normalized units) and increased LF:HF, and the interpretation of findings in these studies varies widely [9,15,23,24,25,26,27,28,29,30,31,32,33,34,35,36].…”

Análise Da Atividade Autonômica Cardíaca Sobre O Fator Obesidade Em Crianças: Uma Revisão Integrativa

“…The search of Freitas et al 22 analyzed cardiac autonomic dysfunctions in normotensive obese children, finding that indexes such as LF and HF in absolute units, standard deviation of all normal RR intervals and the square root of the average square of differences between adjacent normal RR intervals, showed no significant differences between the obese and non-obese groups. The indexes of percentage of adjacent RR intervals with difference of duration greater than 50 milliseconds and HF in normalized units showed significant reduction and LF in normalized units and LF/HF were higher in the obese group.…”