Keselbrener L, Akselrod S, Ahiron A, Eldar M, Barak Y, Rotstein Z
Abramson Center of Medical Physics, Tel Aviv University, Israel.
Clin Auton Res. 2000 Aug;10(4):169-75. doi: 10.1007/BF02291352.
Time-dependent frequency decomposition of fluctuations in cardiovascular signals (heart rate [HR], blood pressure, and blood flow) provides noninvasive and quantitative evaluation of autonomic activity during transient and steady-state conditions. This method was applied during a change of position from supine to standing in patients with multiple sclerosis (MS) who experienced unexplained fatigue and in age-matched control subjects. No difference in response to standing, as reflected in the time domain parameters (mean HR, mean blood pressure, and mean blood flow), was observed between patients with MS and control subjects. Moreover, no difference was observed in very-low-frequency and low-frequency (related to sympathetic activity) content of HR, blood pressure, blood flow, or high-frequency content of HR (related to parasympathetic activity). The only spectral estimates that showed a significant difference between groups were the ratio of low-frequency to high-frequency content of HR and low-frequency content of HR normalized to total power. Both these parameters provide an estimate of the sympathovagal balance. A significant increase in these two estimates on standing was observed in control subjects only, indicating possible impairment of the sympathovagal balance response to standing in patients with MS who experienced fatigue. The authors observed a significant age dependence between close age subgroups, which occurred in the MS group only and was observed in some of the investigated spectral estimates that reflect vagal activity. Therefore, the authors assumed that age-related reduction in vagal activity occurred earlier in patients with MS who experienced fatigue. This reduction could also explain the lack of increase in the sympathovagal balance on standing. To validate this enhanced age dependence, further investigation should be performed in a larger group of subjects with a wider age range.
心血管信号（心率[HR]、血压和血流）波动的时间依赖性频率分解为瞬态和稳态条件下的自主神经活动提供了无创且定量的评估。该方法应用于患有无法解释的疲劳的多发性硬化症（MS）患者以及年龄匹配的对照受试者从仰卧位到站立位的体位变化过程中。在MS患者和对照受试者之间，未观察到在时域参数（平均心率、平均血压和平均血流）中所反映出的对站立的反应差异。此外，在心率、血压、血流的极低频和低频（与交感神经活动相关）成分或心率的高频成分（与副交感神经活动相关）方面也未观察到差异。两组之间唯一显示出显著差异的频谱估计值是心率的低频与高频成分之比以及归一化至总功率的心率低频成分。这两个参数均提供了交感迷走神经平衡的估计值。仅在对照受试者中观察到站立时这两个估计值显著增加，这表明经历疲劳的MS患者对站立的交感迷走神经平衡反应可能受损。作者观察到在年龄相近的亚组之间存在显著的年龄依赖性，这仅在MS组中出现，并且在一些反映迷走神经活动的研究频谱估计值中观察到。因此，作者推测经历疲劳的MS患者迷走神经活动与年龄相关的降低出现得更早。这种降低也可以解释站立时交感迷走神经平衡缺乏增加的现象。为了验证这种增强的年龄依赖性，应在年龄范围更广的更大规模受试者群体中进行进一步研究。
