The application of methods drawn from nonlinear and stochastic dynamics to the analysis of cardiovascular time series is reviewed, with particular reference to the identification of changes associated with ageing. The natural variability of the heart rate (HRV) is considered in detail, including the respiratory sinus arrhythmia (RSA) corresponding to modulation of the instantaneous cardiac frequency by the rhythm of respiration. HRV has been intensively studied using traditional spectral analyses, e.g. by Fourier transform or autoregressive methods, and, because of its complexity, has been used as a paradigm for testing several proposed new methods of complexity analysis. These methods are reviewed. The application of time–frequency methods to HRV is considered, including in particular the wavelet transform which can resolve the time-dependent spectral content of HRV. Attention is focused on the cardio-respiratory interaction by introduction of the respiratory frequency variability signal (RFV), which can be acquired simultaneously with HRV by use of a respiratory effort transducer. Current methods for the analysis of interacting oscillators are reviewed and applied to cardio-respiratory data, including those for the quantification of synchronization and direction of coupling. These reveal the effect of ageing on the cardio-respiratory interaction through changes in the mutual modulation of the instantaneous cardiac and respiratory frequencies. Analyses of blood flow signals recorded with laser Doppler flowmetry are reviewed and related to the current understanding of how endothelial-dependent oscillations evolve with age: the inner lining of the vessels (the endothelium) is shown to be of crucial importance to the emerging picture. It is concluded that analyses of the complex and nonlinear dynamics of the cardiovascular system can illuminate the mechanisms of blood circulation, and that the heart, the lungs and the vascular system function as a single entity in dynamical terms. Clear evidence is found for dynamical ageing.

中文翻译：

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心血管衰老的非线性动力学

回顾了从非线性和随机动力学中提取的方法在心血管时间序列分析中的应用，特别参考了与衰老相关的变化的识别。心率 (HRV) 的自然变异性被详细考虑，包括呼吸性窦性心律失常 (RSA) 对应于呼吸节律对瞬时心脏频率的调制。HRV 已经使用传统的频谱分析进行了深入研究，例如通过傅立叶变换或自回归方法，并且由于其复杂性，已被用作测试几种提出的复杂性分析新方法的范例。审查这些方法。考虑将时频方法应用于 HRV，特别包括小波变换，它可以解析 HRV 的时间相关频谱内容。通过引入呼吸频率变异性信号 (RFV)，注意力集中在心肺相互作用上，该信号可以通过使用呼吸努力传感器与 HRV 同时获得。回顾了分析相互作用振荡器的当前方法并将其应用于心肺数据，包括用于量化同步和耦合方向的方法。这些通过瞬时心脏和呼吸频率的相互调制的变化揭示了衰老对心肺相互作用的影响。回顾了用激光多普勒血流仪记录的血流信号的分析，并与目前对内皮依赖性振荡如何随年龄演变的理解相关：血管的内衬（内皮）被证明对新兴图片至关重要。结论是，对心血管系统复杂和非线性动力学的分析可以阐明血液循环的机制，并且心脏、肺和血管系统在动力学方面作为一个整体起作用。发现了动态老化的明确证据。结论是，对心血管系统复杂和非线性动力学的分析可以阐明血液循环的机制，并且心脏、肺和血管系统在动力学方面作为一个整体起作用。发现了动态老化的明确证据。结论是，对心血管系统复杂和非线性动力学的分析可以阐明血液循环的机制，并且心脏、肺和血管系统在动力学方面作为一个整体起作用。发现了动态老化的明确证据。