Boudreau Philippe, Dumont Guy, Kin N M K Ng Ying, Walker Claire-Dominique, Boivin Diane B
Centre for Study and Treatment of Circadian Rhythms, Douglas Mental Health University Institute, McGill University, Montreal, Quebec, Canada.
Annu Int Conf IEEE Eng Med Biol Soc. 2011;2011:681-2. doi: 10.1109/IEMBS.2011.6090153.
The frequency of adverse cardiovascular events is greater in the morning compared to its 24-hour average. A circadian variation in the regulation of the cardiovascular system could contribute to this increased cardiovascular risk in the morning. Indeed, circadian rhythms have been shown for a wide array of physiological processes. Using an ultradian sleep-wake cycle (USW) procedure, we sought to determine how heart rate (HR) and heart rate variability (HRV) correlate with the well-characterized circadian rhythms of cortisol and melatonin secretion. Specific HRV components, namely the low frequency (LF) power, high frequency (HF) power, and the LF:HF ratio can be used as markers of the autonomic modulation of the heart. Cross-correlation between HRV parameters and hormonal rhythms demonstrated that mean RR interval is significantly phase-advanced relative to salivary cortisol and urinary 6-sulfatoxy-melatonin (UaMt6s). Parasympathetic modulation of the heart (HF power) was phase-advanced relative to cortisol, but was in-phase with UaMt6s levels. Maximal correlation of the sympathovagal balance (the LF:HF ratio) had no significant lag compared to cortisol secretion and UaMt6s excretion. The protective effect of the parasympathetic nervous system at night, combined with the putative risk associated with the sympathetic nervous system peaking in the morning, could be associated with the increased cardiovascular risk observed in the morning hours.
与24小时平均水平相比，早晨不良心血管事件的发生频率更高。心血管系统调节中的昼夜节律变化可能导致早晨心血管风险增加。事实上，昼夜节律已在一系列生理过程中得到证实。我们采用超日睡眠-觉醒周期（USW）程序，试图确定心率（HR）和心率变异性（HRV）如何与皮质醇和褪黑素分泌的特征性昼夜节律相关。特定的HRV成分，即低频（LF）功率、高频（HF）功率和LF:HF比值，可作为心脏自主调节的标志物。HRV参数与激素节律之间的交叉相关性表明，平均RR间期相对于唾液皮质醇和尿6-硫酸氧褪黑素（UaMt6s）显著相位提前。心脏的副交感神经调节（HF功率）相对于皮质醇相位提前，但与UaMt6s水平同相。交感神经与迷走神经平衡（LF:HF比值）的最大相关性与皮质醇分泌和UaMt6s排泄相比无显著滞后。夜间副交感神经系统的保护作用，加上早晨交感神经系统假定的风险峰值，可能与早晨时段观察到的心血管风险增加有关。
