目的 对学龄期肥胖儿童的心率减速力（DC）、心率加速力（AC）及心率变异性（HRV）进行分析，并观察肥胖儿童体重指数（BMI）与DC、AC及HRV的相关性。方法 选取学龄期肥胖儿童108例，其中血脂正常组75例，血脂异常组33例，另选取103例学龄期健康儿童为对照组。对所有受试者行24 h动态心电图检查，分别将肥胖组与对照组、肥胖儿童中血脂异常组与血脂正常组的DC、AC及HRV进行比较，并将肥胖儿童的BMI与DC、AC及HRV进行相关性分析。结果 肥胖组的DC、RR间期总体标准差（SDNN）、RR间期平均值的标准差（SDANN）、相邻RR间期差值的均方根（RMSSD）、低频功率（LF）、高频功率（HF）均低于对照组，AC高于对照组（P < 0.05）。肥胖儿童中血脂异常组的DC、SDNN、SDANN、RMSSD、LF、HF均低于血脂正常组，AC、BMI高于血脂正常组（P < 0.01）。肥胖儿童BMI与DC、SDNN、SDANN、RMSSD、HF呈明显负相关（P < 0.05）；与AC呈明显正相关（P < 0.05）。结论 学龄期肥胖儿童的自主神经功能受损，表现为迷走神经张力减低，其中合并血脂异常者以上表现尤为突出。肥胖程度越高，迷走神经张力越低，发生心血管疾病的危险性可能越大。

Objective To analyze the deceleration capacity (DC) of heart rate, acceleration capacity (AC) of heart rate, and heat rate variability (HRV) in obese school-age children, and to observe the correlations of BMI with DC, AC, and HRV in these children. Methods A total of 108 obese school-age children were selected, including 75 cases of ortholiposis and 33 cases of dyslipidemia. A total of 103 healthy school-age children were selected as control group. All the subjects underwent 24-hour ambulatory electrocardiography. The comparisons of DC, AC, and HRV were made between the obese and control groups, as well as between children with ortholiposis and dyslipidemia in the obese group. The correlations of BMI with DC, AC, and HRV were analyzed in the obese group. Results The obese group showed lower DC, standard deviation of normal-to-normal R-R intervals (SDNN), standard deviation of the average normal-to-normal intervals (SDANN), root mean square of successive differences (RMSSD), low-frequency power (LF), and high-frequency power (HF) than the control group. The AC of the obese group was significantly higher than that of the control group (P < 0.05). In the obese group, children with dyslipidemia had significantly lower DC, SDNN, SDANN, RMSSD, LF, and HF, but significantly higher AC and BMI, as compared with those with ortholiposis (P < 0.01). In the obese group, BMI was negatively correlated with DC, SDNN, SDANN, RMSSD, and HF (P < 0.05), but positively correlated with AC (P < 0.05). Conclusions Obese school-age children have impaired autonomic nerve function, presenting with reduced vagal tone, which is particularly prominent in those with dyslipidemia. The more obese the children, the lower the vagal tone, which may increase the risks of cardiovascular diseases.