Murakawa Y, Inoue H, Nozaki A, Sugimoto T
Second Department of Internal Medicine, Tokyo University Hospital, Japan.
Am J Cardiol. 1992 Feb 1;69(4):339-43. doi: 10.1016/0002-9149(92)90230-v.
To elucidate the role of sympathovagal interaction in diurnal variation of QT interval, 24-hour ambulatory electrocardiographic recordings from 56 subjects (23 control subjects, 18 patients with atherosclerotic coronary artery disease, and 15 patients with diabetes mellitus) were studied. The QT interval at a heart rate of 60 beats/min (QT60) was determined for each of the day and night periods by regression analysis. Sympathetic and parasympathetic activities were assessed by spectral analysis of heart rate variability and represented by the low- and high-frequency components, respectively. The proportion of high-frequency component to the sum of low- and high-frequency components was used as an index of sympathovagal balance. The relative increase in QT60 at night (delta QT60 [%]) was larger in control subjects (4.2 +/- 2.1%) than in patients with coronary artery disease (2.2 +/- 1.8%; p less than 0.01) and diabetes mellitus (-1.5 +/- 4.0%; p less than 0.001). When the data from the 3 subject groups were pooled and analyzed, delta QT60 was correlated with the change in the sympathovagal balance (r = 0.554; p less than 0.001). Low-frequency component in the day alone was also related with delta QT60 (r = 0.554; p less than 0.001), but the ratio or difference of the high-frequency component value between day and night was not. These results indicate that although change in sympathovagal balance was responsible for the diurnal variation in QT interval, the enhanced sympathetic activity in the day was a major determinant of this phenomenon.
为阐明交感迷走神经相互作用在QT间期昼夜变化中的作用，对56名受试者（23名对照者、18名动脉粥样硬化性冠状动脉疾病患者和15名糖尿病患者）的24小时动态心电图记录进行了研究。通过回归分析确定每个白天和夜间时段心率为60次/分钟时的QT间期（QT60）。通过心率变异性频谱分析评估交感神经和副交感神经活动，分别用低频和高频成分表示。高频成分占低频和高频成分总和的比例用作交感迷走神经平衡指数。对照者夜间QT60的相对增加（ΔQT60 [%]）（4.2±2.1%）大于冠状动脉疾病患者（2.2±1.8%；p<0.01）和糖尿病患者（-1.5±4.0%；p<0.001）。当将3组受试者的数据汇总并分析时，ΔQT60与交感迷走神经平衡的变化相关（r = 0.554；p<0.001）。仅白天的低频成分也与ΔQT60相关（r = 0.554；p<0.001），但白天和夜间高频成分值的比值或差值则不然。这些结果表明，虽然交感迷走神经平衡的变化是QT间期昼夜变化的原因，但白天交感神经活动增强是这一现象的主要决定因素。
