Department of Physiology, Jessenius Faculty of Medicine, Comenius University, Martin, Slovak Republic.
Physiol Meas. 2011 Sep;32(9):1425-37. doi: 10.1088/0967-3334/32/9/006. Epub 2011 Jul 28.
Cardiovascular control acts over multiple time scales, which introduces a significant amount of complexity to heart rate and blood pressure time series. Multiscale entropy (MSE) analysis has been developed to quantify the complexity of a time series over multiple time scales. In previous studies, MSE analyses identified impaired cardiovascular control and increased cardiovascular risk in various pathological conditions. Despite the increasing acceptance of the MSE technique in clinical research, information underpinning the involvement of the autonomic nervous system in the MSE of heart rate and blood pressure is lacking. The objective of this study is to investigate the effect of orthostatic challenge on the MSE of heart rate and blood pressure variability (HRV, BPV) and the correlation between MSE (complexity measures) and traditional linear (time and frequency domain) measures. MSE analysis of HRV and BPV was performed in 28 healthy young subjects on 1000 consecutive heart beats in the supine and standing positions. Sample entropy values were assessed on scales of 1-10. We found that MSE of heart rate and blood pressure signals is sensitive to changes in autonomic balance caused by postural change from the supine to the standing position. The effect of orthostatic challenge on heart rate and blood pressure complexity depended on the time scale under investigation. Entropy values did not correlate with the mean values of heart rate and blood pressure and showed only weak correlations with linear HRV and BPV measures. In conclusion, the MSE analysis of heart rate and blood pressure provides a sensitive tool to detect changes in autonomic balance as induced by postural change.
心血管控制作用于多个时间尺度，这给心率和血压时间序列带来了很大的复杂性。多尺度熵（MSE）分析已被开发出来，以量化时间序列在多个时间尺度上的复杂性。在以前的研究中，MSE 分析确定了在各种病理条件下心血管控制受损和心血管风险增加。尽管 MSE 技术在临床研究中越来越被接受，但缺乏自主神经系统参与心率和血压 MSE 的信息。本研究的目的是探讨直立挑战对心率和血压变异性（HRV、BPV）的 MSE 的影响，以及 MSE（复杂性度量）与传统线性（时域和频域）度量之间的相关性。在 28 名健康年轻受试者中，在仰卧和站立位置下对 1000 个连续心跳进行了 HRV 和 BPV 的 MSE 分析。样本熵值在 1-10 的尺度上进行评估。我们发现，心率和血压信号的 MSE 对由仰卧位变为直立位引起的自主平衡变化敏感。直立挑战对心率和血压复杂性的影响取决于所研究的时间尺度。熵值与心率和血压的平均值没有相关性，仅与线性 HRV 和 BPV 测量值有较弱的相关性。总之，心率和血压的 MSE 分析提供了一种敏感的工具，可以检测由体位变化引起的自主平衡变化。
