台灣花蓮12-13歲之兒童約有15%肥胖,相較於正常體重者其BMI,血壓,及胰島素阻力較高,其副交感HF較低且LF%及LF/HF較高

Heart Rate Variability in Taiwanese Obese Children

Chen-Chung Fu, Yin-Ming Li1, Dee Pei, Chien-Lin Chen, Huey-Ming Lo2, Du-An Wu, Terry BJ Kuo3

Department of Internal Medicine, Family Medicine1, Buddhist Tzu Chi General Hospital, Hualien, Taiwan; Department

of Internal Medicine2, Shin Kong Wu Ho Su Memorial Hospital, Taipei, Taiwan; Institute of Neuroscience3, Tzu Chi

University, Hualien, Taiwan

www.tzuchi.com.tw/file/tcmj/95-3/18-3-199-204.pdf

ABSTRACT

Objective: The primary purpose of the present community-based study was to investigate early changes in cardiac autonomic function in obese children. Materials and Methods: A survey of juvenile obesity in Hualien in eastern Taiwan was performed in

2002. A total of 1,724 adolescents who were 12 or 13 years old were recruited. The overall prevalences of normal weight, overweight

and obese adolescents were 71.5% 13.1%, and 15.4%, respectively. A stratified random sampling scheme was performed.

We selected 100, 50 and 75 subjects from the above-mentioned three groups, and invited them to join this study. Totally, 170

students (normal-weight: overweight: obese= 81: 34: 55) participated in this study. They received blood checks and a heart rate

variability (HRV) examination. The homeostasis model assessment of insulin resistance (HOMA-IR) was used to evaluate insulin

sensitivity. Results: Compared with the normal-weight group, the obese children had significantly elevated body mass indexes

(BMI), HOMA-IR, and systolic and diastolic blood pressure levels. In addition, compared to their normal weight counterparts,

obese children had significantly reduced high-frequency power (HF) but elevated low-frequency power in normalized units (LF %),

and elevated ratios of low-frequency power to high-frequency power (LF/HF ratio). Further analyses revealed that compared with

the normal weight counterparts; obese boys had significantly reduced HF but elevated LF % and LF/HF ratios. Among obese girls,

the HF was reduced significantly, and LF% and the LF/HF ratio were increased, though not significantly. In stepwise multiple

regression analysis, the BMI and heart rate were negatively associated with the HF component and positively associated with the

LF/HF ratio and LF %. For every 1 kg/m2 increment in the BMI, the LF/HF ratio and LF % components of HRV increased ln(0.02)

and 0.42% respectively, while HF decreased 0.03 ln(ms2). Boys had a higher LF/HF ratio and LF % than girls. Conclusions: The

obese boys and girls had increased insulin resistance and changes in autonomic nervous function that included reduced parasympathetic

control and obese boys had elevated sympathovagal modulation. Gender-related autonomic differences, such as girls having

lower sympathetic modulations of HRV, were also noted. ( Tzu Chi Med J 2006; 18:199-204)

Key words: obese children, heart rate variability, autonomic nerve dysfunction