Age-related alterations in the fractal scaling of cardiac interbeat interval dynamics
Age-related alterations in the fractal scaling of cardiac interbeat interval dynamics
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DOI：
10.1152/ajpregu.1996.271.4.r1078
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发表时间：
1996-10-01
影响因子：
2.8
通讯作者：
Lipsitz, LA
中科院分区：
文献类型：
--
作者：
Iyengar, N;Peng, CK;Lipsitz, LA
我们推测，衰老与健康窦性心律心搏间期动力学特征的碎裂状长程相关性的破坏有关。对10名青年(21~34岁)和10名老年(68~81岁)经过严格筛选的健康受试者进行了连续120min的仰卧位静息心电图记录。我们使用标准的时间域和频域统计量来分析节拍间隔时间序列，并使用去趋势波动分析来量化长程相关特性。在健康的年轻受试者中，节拍间期显示出分形标度，波动分析的标度指数(α)接近1.0。在健康老年人组中，心搏间期时间序列有两个标度区域。在短距离上，节拍间隔波动类似于随机行走过程(布朗噪声，α=1.5)，而在较长范围内，它们类似于白噪声(α=0.5)。老年组的短尺度指数(α(S))和长程尺度指数(α(1))与青年组比较有显著差异(α(2)=1.12+/-0.19vs.0.90+/-0.14，P=0.009；α(1)=0.75+/-0.17vs.0.99+/-0.10，P=0.002)。从一个标度区域到另一个标度区域的交叉行为可以被建模为一阶自回归过程，这与来自四个老年受试者的数据非常吻合。这意味着，在这些受试者中，一个单一的特征时间尺度可能主导着心跳控制。心跳动力学中与年龄相关的分形组织的丧失可能反映了整合的生理调节系统的退化，并可能损害个体适应压力的能力。
We postulated that aging is associated with disruption in the fractallike long-range correlations that characterize healthy sinus rhythm cardiac interval dynamics. Ten young (21-34 yr) and 10 elderly (68-81 yr) rigorously screened healthy subjects underwent 120 min of continuous supine resting electrocardiographic recording. We analyzed the interbeat interval time series using standard time and frequency domain statistics and using a fractal measure, detrended fluctuation analysis, to quantify long-range correlation properties. In healthy young subjects, interbeat intervals demonstrated fractal scaling, with scaling exponents (alpha) from the fluctuation analysis close to a value of 1.0. In the group of healthy elderly subjects, the interbeat interval time series had two scaling regions. Over the short range, interbeat interval fluctuations resembled a random walk process (Brownian noise, alpha = 1.5), whereas over the longer range they resembled white noise (alpha = 0.5). Short (alpha(s))- and long-range (alpha(1)) scaling exponents were significantly different in the elderly subjects compared with young (alpha(2) = 1.12 +/- 0.19 vs. 0.90 +/- 0.14, respectively, P = 0.009; alpha(1) = 0.75 +/- 0.17 vs. 0.99 +/- 0.10, respectively, P = 0.002). The crossover behavior from one scaling region to another could be modeled as a first-order autoregressive process, which closely fit the data from four elderly subjects. This implies that a single characteristic time scale may be dominating heartbeat control in these subjects. The age-related loss of fractal organization in heartbeat dynamics may reflect-the degradation of integrated physiological regulatory systems and may impair an individual's ability to adapt to stress.