Obesity is characterized by hemodynamic and metabolic alterations. Autonomi
c control on cardiac function involvement is controversial. The aim of the
study was to assess early sign of cardiac autonomic dysfunction in obesity,
using time- and frequency-domain heart rate variability (HRV) analysis in
a pediatric population. Methods: 32 obese children (OB) (17 M, 15 F; 13.9 /- 1.7 y) were compared with 13 healthy lean subjects (7 M, 6 F; 12.9 +/- 1
.6 y). For each participant, the authors performed a clinical examination,
laboratory testing, blood pressure (BP) measurements, and 24-hour electroca
rdiograph/ambulatory BP monitoring. The spectral power was quantified in to
tal power, low-frequency (LF) power, index of sympathetic tone, high-freque
ncy (HF) power, index of vagal tone, and LF/HF ratio. Low frequency and HF
were averaged to obtain 3 measures: 24-hour, daytime, and nighttime levels.
Total, long-term, and short-term time-domain HRV values were calculated. R
esults: The obese children had higher casual and ambulatory BP, and higher
fasting glucose, insulin, and triglyceride levels. Overall HRV values were
not significantly lower in OB. The obese children had significantly lower 2
4-hour and nighttime high-frequency normalized units, and time-domain measu
res of vagal activity. Low-frequency power showed an inverse but not signif
icant pattern. The OB group had significantly greater 24-hour and nighttime
LF/HF ratios. Conclusions: The authors found an increase in heart rate and
in BP associated with parasympathetic heart rate control decrease in stabi
lized obese normotensive children.