分形维数在头低位期间心率变异分析中的应用

Application of Fractal Dimension in Heart Rate Variability Analysis during Head-down Tilt.

目的将分形维数应用于心率变异性分析,分析头低位实验过程中心血管系统的非线性变化趋势。方法对10名被试者进行头低位模拟失重实验,每个人前后做2次,共20组实验数据,记录心电信号并用分形维数进行分析。结果与平卧位相比,头低位15～20min、20～25min、25～30min和恢复期的R R间期的标准差显著升高;头低位20～25min的相邻R R间期差值的均方根显著升高;头低位0～5min、5～10min、10～15min、20～25min、25～30min和恢复期的分形维数显著高于平卧位。结论头低位期间心率变异性升高,心血管系统复杂性升高;分形维数应用于心率变异性的分析是可行的。

Objective The paper applies the fractal dimension to heart rate variability(HRV), and discusses the changes of the fractal dimension of cardiovascular system during head down tilt(HDT). Method ECG of 10 subjects were recorded during HDT, the experiment was repeated in each subject. Fractal dimension was used to analyze the HRV. Result Compared to supine before HDT, the standard deviation of all normal to normal RR intervals(SDNN) at 15～20 min,20～25 min,25～30 min and restoration increased significantly; the root mean square of successive differences between adjacent normal cycles(rMSSD) at 20～25 min increased significantly; the fractal dimension at 0～5 min,5～10 min,10～15 min,20～25 min,25～30 min and restoration increased significantly.Conclusion The result shows that HRV and the nonlinearity of cardiovascular system increase during HDT. It is feasible that the fractal dimension can be used for analyzing HRV.