基于关联维数和最大Lyapunov指数的运动HRV信号的研究

Analysis of EHRV based on Correlation Dimension and Largest Lyapunov Exponent

采用非线性方法研究了应激条件下心血管系统的调节功能状况。以30例中老年高血压患者和30例年轻健康者作为研究对象,首先采集阶梯试验中的动态心电信号,通过信号预处理获得运动心率变异性(exercise heart rate variability,EHRV),然后从运动前静息期和运动后恢复期EHRV中提取两个非线性指标——关联维数和最大Lyapunov指数,最后进行了统计分析。发现在两组测试对象中,除了运动前的最大Lyapunov指数,其余三个指标均有显著差异性,可有效区分高血压患者和健康者两组人群。对于健康者,运动前与运动后的关联维数、最大Lyapunov指数分别都具有显著差异性,而高血压患者运动前后的两个非线性指标都不具有显著差异性。说明健康者的交感神经系统在应激状态下能作出适应性的调节,而高血压患者此调节功能不明显。

To study function of cardiovascular system in stress status with non - linear analysis. Two groups including 30 elder hypersentives and 30 young healthy controls were tested as subjects. Firstly EHRV was obtained by preprocessing the exercise ECG recorded in step exercise. Then correlation dimension （CD） and Largest Lyapunov exponent （LLE） were extracted from two stages in exercise, which contained the rest period before exercise （AES） and the recovering period after exercise （PES）. Finally statistics analysis was operated. Statistics indicated that except AES-LLE,the other three non - linear indexes namely AES-CD,PES-CD and PES-LLE had significant difference respectively between two groups, which could be used to classify two groups effectively. For healthy controls, there was significant difference for two indexes between AES and PES, while no difference for hypertensive group.Results indicate that sympathetic system of healthy controls can give adjustment respond to stress status compared with hypersentives.