目的　监测小儿甲状腺功能亢进症 (简称甲亢 ) 2 4h心率变异性 (HRV)的昼夜规律 ,探讨其自主神经功能异常的意义。方法　 2 4h动态心电图记录后 ,分别对 13例甲亢和 2 6例正常小儿 (对照组 )的HRV进行分析。结果　① 2 4h总HRV时域和频域指标提示甲亢组与对照组比较均有显著差异 (P <0 0 1)。②清醒期和睡眠期频域指标比较 :对照组低频标准单位 (LFNU)、低频 /高频比率 (LF/HF)在清醒期明显增高 (P <0 0 1) ,高频带 (HF)、高频标准单位 (HFNU)在睡眠期明显增高 (P <0 0 1) ;甲亢组总功率谱密度 (TP)、极低频带 (VLF)、低频带 (LF)、HF、LFNU、HFNU、LF/HF在清醒期和睡眠期比较无显著差异。③各组 2 4h的HRV时域动态变化比较 :对照组 2 4h的HRV时域变化有明显昼夜节律 ,以相邻正常RR间期差值均方根 (RMSSD)和相邻正常RR间期差值 >5 0ms占RR间期总数的百分比 (PNN50 )指标最敏感 ;甲亢组 2 4h的HRV时域各指标明显低于对照组 (P <0 0 1) ,失去昼夜规律。结论　甲亢患儿心脏自主神经受损 ,以迷走神经更严重。由于持续性的甲状腺素刺激 ,而表现为持续性交感神经占优势 ,失去昼夜规律 ,及时控制甲亢 ,并重新调整自主神经平衡对甲亢性心脏病发生有不可忽视的价值 Objective To monitor the circadian rhythm of heart rate variability (HRV) at 24 hours in children with hyperthyroidism (Hyperthyroidism) and to explore the significance of abnormal autonomic nervous function. Methods After 24 h Holter recording, the HRVs of 13 cases of hyperthyroidism and 26 normal children (control group) were analyzed respectively. Results ① The 24 h total HRV time-domain and frequency-domain indexes indicated that there was significant difference between hyperthyroidism group and control group (P <0.01). (2) Compared with LFNU and LF / HF in the control group, the frequency of LF / HF increased significantly in awake period (P <0.01), high frequency (HF) The frequency of high frequency standard unit (HFNU) was significantly increased during sleep (P <0.01). The total power spectral density (TP), very low frequency band (VLF), low frequency band / HF in the awake and sleep no significant difference. (3) Comparison of HRV time domain changes at 24 hours of each group: The circadian rhythm of HRV in 24 hours of the control group had obvious circadian rhythm. The RMSSD of adjacent normal RR interval and the difference of adjacent normal RR interval The value of> 5 0ms was the most sensitive to the index of the total number of RR intervals (PNN50). The indexes of HRV in 24 h of hyperthyroidism group were significantly lower than those in control group (P <0.01), and the circadian rhythm was lost. Conclusion The autonomic nervous system in children with hyperthyroidism is impaired and the vagus nerve is more serious. Due to persistent thyroid hormone stimulation, which is characterized by persistent dominant sympathetic, loss of circadian rhythm, timely control of hyperthyroidism, and readjust the balance of autonomic nervous hyperthyroidism heart disease can not be ignored