小鼠急性心肌缺血ECG的小波分析

Wavelet Analysis of ECG in Rats with Acute Myocardial Ischemia

结扎小鼠冠状动脉前降支造成心肌缺血 10 m in,采集小鼠在正常和急性心肌缺血下的 ECG信号。采样频率选为 5 0 0 Hz,连续采集 2 0 s的数据。用具有对数频率分辨率的小波变换技术来分析 ECG信号。选 Mexican Hat小波为母函数 ,尺度因子 a在区间 [0 .0 0 12 5 ,2 .5 ]取值 ,则相应的带通滤波器中心频率为 2 0 0～ 0 .1Hz。计算出 ECG信号在相应尺度下的小波分解系数 ,然后求出在频率 f处带宽为Δf内的信号能量 ,得出了小鼠急性心肌缺血前后ECG信号能量随频率 f的变化规律。结果表明 :小鼠急性心肌缺血时 ECG信号平均能量在 0 .1～ 1.0 Hz和 1～ 10Hz段是增加的 ,在 10～ 2 0 0

The myocardial ischemia model was established by ligating the left anterior descending artery of rat for 10 min. The ECG signal were collected from the rats with acute myocardial ischemia and from the healthy rats as controls. The frequency of data acquisition was 500 Hz. The measurement time around 20 seconds was chosen. The wavelet transform technique, a time frequency method with logarithmic frequency resolution, was used to analyze the ECG signal. Mexican Hat wavelet was used and the scale factor was chosen from an interval [0.00125,2.5] for evaluating its wavelet coefficient at corresponding scale respectively, thus the central frequency of the bandpass filter was within a range of 200 0 1Hz. Then we evaluated the signal energy in the bandwidth Δ f at frequency f . A variational rule was obtained,i.e. rat's ECG signal energy varies with frequency before and after myocardial ischemia. The results showed that in the rat suffering from acute myocardial ischemia the average signal energy increases in 0.1 1.0Hz and 1 10Hz segments and decreases in 10 200Hz segment.