目的　探讨小儿单纯性室性早搏 (VPC)的昼夜变化规律及其临床意义。方法　对单纯性VPC患儿进行 2 4小时动态心电图 (DCG)监测、运动试验、自主神经功能及心室晚电位 (VLP)检查。结果　 30例中 ,13例(4 3 3 % )为日间型 ,其中 12例属交感性VPC ;10例 (33 3 % )为夜间型 ,均属迷走性VPC。日间型VPC在夜间睡眠时 ,VPC的频率、严重度下降 ,而夜间型则相反。日间型组 8/13例 (6 1 5 % )运动后早搏增加 ,2 /13例 (15 4% )无变化 ,而夜间型仅 1/10例 (10 0 % )无变化 (P <0 0 1)。本组 2 0例做VLP检查均正常。结论　单纯性日间型VPC可能是交感神经张力增高所致 ;而夜间型与迷走神经张力增高有关。运动试验对夜间型VPC的病理性判断较有意义 Objective To investigate the regular pattern of diurnal changes in children with simple ventricular premature beats (VPC) and its clinical significance. Methods 24-hour ambulatory electrocardiogram (DCG) monitoring, motor test, autonomic nerve function and ventricular late potentials (VLP) were performed in children with simple VPC. Results Among the 30 cases, 13 cases (43.3%) were daytime type. Twelve of them were symptomatic VPCs and 10 cases (33.3%) were nocturnal ones, all of which were vagal VPCs. Daytime VPC Sleep at night, VPC frequency, severity decreased, while the night is the opposite. In the daytime group, 8/13 cases (65.1%) had increased premature beats, 2/13 (15.4%) had no change, while only 1/10 of 10 cases (10%) had no change at daytime 0 1). The group of 20 cases of VLP were normal. Conclusions Simple daytime VPC may be caused by increased sympathetic tone, while nighttime type is associated with increased vagal tone. Exercise test on the pathological VPC night-time more meaningful