Keselbrener L, Akselrod S
Abramson Institute of Medical Physics, Sackler Faculty of Exact Sciences, Tel Aviv University, Israel.
IEEE Trans Biomed Eng. 1996 Aug;43(8):789-802. doi: 10.1109/10.508542.
The Selective Discrete Fourier transform (DFT) Algorithm [SDA] method for the calculation and display of time-frequency distribution has been developed and validated. For each time and frequency, the algorithm selects the shortest required trace length and calculates the corresponding spectral component by means of DFT. This approach can be extended to any cardiovascular related signal and provides time-dependent power spectra which are intuitively easy to consider, due to their close relation to the classical spectral analysis approach. The optimal parameters of the SDA for cardiovascular-like signals were chosen. The SDA perform standard spectral analysis on stationary simulated signals as well as reliably detect abrupt changes in the frequency content of nonstationary signals. The SDA applied during a stimulated respiration experiment, accurately detected the changes in the frequency location and amplitude of the respiratory peak in the heart rate (HR) spectrum. It also detected and quantified the expected increase in vagal tone during vagal stimuli. Furthermore, the HR time-dependent power spectrum displayed the increase in sympathetic activity and the vagal withdrawal on standing. Such transient changes in HR control would have been smeared out by standard heart rate variability (HRV), which requires consideration of long trace lengths. The SDA provides a reliable tool for the evaluation and quantification of the control exerted by the Central Nervous System, during clinical and experimental procedures resulting in nonstationary signals.
用于计算和显示时频分布的选择性离散傅里叶变换（DFT）算法[SDA]方法已经得到开发和验证。对于每个时间和频率，该算法选择所需的最短迹线长度，并通过DFT计算相应的频谱分量。这种方法可以扩展到任何与心血管相关的信号，并提供与时间相关的功率谱，由于它们与经典频谱分析方法密切相关，因此直观上易于理解。选择了针对类心血管信号的SDA的最佳参数。SDA对平稳模拟信号执行标准频谱分析，并可靠地检测非平稳信号频率内容的突然变化。在刺激呼吸实验中应用SDA，准确检测了心率（HR）谱中呼吸峰值的频率位置和幅度变化。它还检测并量化了迷走神经刺激期间迷走神经张力的预期增加。此外，HR随时间变化的功率谱显示了站立时交感神经活动的增加和迷走神经的撤离。心率控制中的这种瞬态变化会被标准心率变异性（HRV）掩盖，而HRV需要考虑较长的迹线长度。SDA为评估和量化中枢神经系统在导致非平稳信号的临床和实验过程中所施加的控制提供了一种可靠的工具。
