心率变异和RT变异频域分析的方法学研究

心率变异作为检测自主神经系统功能平衡状态的无创性指标，日益受到重视，已成为心电信号处理中的研究热点之一。ＱＴ是心室肌复极化时间，从另一方面来反映自主神经系统的平衡状态。ＱＴ变异分析在临床应用上与心率变异分析是否有互补作用，目前这方面研究工作开展得不多。由于ＱＴ间期检测困难，一般以ＲＴ间期代替ＱＴ间期。建立了心率变异和ＱＴ变异测定方法。在采集２４ｈ心电信号后，首先要完成标志点的检测。较好地实现了心电Ｒ波标志点的检测和异位心跳的剔除，并采用以相关系数为条件的模板匹配方法检测出Ｔ波标志点。频域分析方法分别通过快速傅里叶变换法（ＦＦＴ）和自回归谱估计法（ＡＲ）实现了２４ｈ三维频谱显示图以及２４ｈＨＦ／ＬＦ和高频能量变化趋势图。以不同的频率控制受试者的呼吸，采集其心电数据，从ＲＲ间期和ＲＴ间期谱分析的结果可以看到，高频峰受到呼吸频率的调制，高频峰可能与迷走神经活动有关。这一过程也检验了心电信号采集、检测和谱分析方法的可靠性。建立的方法为今后进一步深入研究打下了基础。随着心率变异和ＱＴ变异的检测和分析技术的日趋成熟，一定会在一些疾病的早期诊断、监护及预后评估等方面发挥更大的作用

A Methodological Study of Frequency Domain Analysis on Heart Rate Variability and RT Interval Variability

Recently,heart rate variability (HRV) as a non invasive measure for assessing the balance of autonomic nervous system has drawn more attentions and HRV analysis has become a focus of the ECG signal processing.QT interval represents the ventricular repolarization duration.QTV might reflect the balance of autonomic nervous system in other way.QTV analysis might complement HRV analysis.Because of the difficulty in detecting QT interval,RT interval is often used instead of QT interval.HRV and QTV detecting methods have been presented in this paper.After recording 24h ECG signals,R fiducial marks are detected correctly and ectopic beats are removed.T peaks are detected on the basis of templet matching and correlation.The analysis in frequency domain consists of 24h 3 dimensional frequency chart,as well as trends of HF/LF and HF,with fast Fourier tansform and autoregressive techniques.We acquired ECG signals from subjects under controlled respiration in different frequencies.The results of HRV and RTV spectral analysis have shown that HF peak is modulated at the frequency of controlled respiration,which proves that HF peak is dependent on the vagal activity and our method is correct.The establishment of these methods has provided a basis for further research,and the development of HRV and QTV analysis techniques will be more helpful for early diagnosis,monitoring and prognostic assessment of some diseases.