Physiotherapy Department, Federal University of São Carlos, São Carlos, São Paulo, Brazil.
Intern Emerg Med. 2012 Jun;7(3):229-35. doi: 10.1007/s11739-011-0512-z. Epub 2011 Jan 21.
Increasing age is associated with a reduction in overall heart rate variability as well as changes in complexity of physiologic dynamics. The aim of this study was to verify if the alterations in autonomic modulation of heart rate caused by the aging process could be detected by Shannon entropy (SE), conditional entropy (CE) and symbolic analysis (SA). Complexity analysis was carried out in 44 healthy subjects divided into two groups: old (n = 23, 63 ± 3 years) and young group (n = 21, 23 ± 2). It was analyzed SE, CE [complexity index (CI) and normalized CI (NCI)] and SA (0V, 1V, 2LV and 2ULV patterns) during short heart period series (200 cardiac beats) derived from ECG recordings during 15 min of rest in a supine position. The sequences characterized by three heart periods with no significant variations (0V), and that with two significant unlike variations (2ULV) reflect changes in sympathetic and vagal modulation, respectively. The unpaired t test (or Mann-Whitney rank sum test when appropriate) was used in the statistical analysis. In the aging process, the distributions of patterns (SE) remain similar to young subjects. However, the regularity is significantly different; the patterns are more repetitive in the old group (a decrease of CI and NCI). The amounts of pattern types are different: 0V is increased and 2LV and 2ULV are reduced in the old group. These differences indicate marked change of autonomic regulation. The CE and SA are feasible techniques to detect alteration in autonomic control of heart rate in the old group.
随着年龄的增长，心率总体变异性降低，生理动力学的复杂性也发生变化。本研究旨在验证衰老过程中引起的心率自主调节改变是否可以通过香农熵（SE）、条件熵（CE）和符号分析（SA）检测到。在 44 名健康受试者中进行了复杂性分析，分为两组：老年组（n=23，63±3 岁）和年轻组（n=21，23±2 岁）。分析了 SE、CE[复杂性指数（CI）和归一化 CI（NCI）]和 SA（0V、1V、2LV 和 2ULV 模式），这些分析是在仰卧位休息 15 分钟期间从 ECG 记录中获得的短心脏周期序列（200 个心搏）中进行的。具有三个无显著变化的心脏周期的序列（0V），以及具有两个显著不同变化的序列（2ULV），分别反映了交感神经和迷走神经调节的变化。在统计分析中使用了配对 t 检验（或适当情况下的曼-惠特尼秩和检验）。在衰老过程中，模式（SE）的分布与年轻受试者相似。然而，规律性明显不同；老年组的模式更具重复性（CI 和 NCI 降低）。模式类型的数量不同：老年组 0V 增加，2LV 和 2ULV 减少。这些差异表明自主调节明显改变。CE 和 SA 是检测老年组心率自主控制改变的可行技术。
