北京生物醫(yī)學(xué)工程

基于最大Lyapunov指數(shù)的心音信號(hào)混沌特性分析

Chaotic characteristics of heart sound signals based on the largest Lyapunov exponent

作者：孫麗莎孫麗麗彭響華

單位：                      汕頭大學(xué)電子工程系(廣東汕頭 515063)        

關(guān)鍵詞：相空間重構(gòu)；最大Lyapunov指數(shù)；S1心音；S2心音；混沌特性

分類號(hào)：

出版年·卷·期（頁碼）：2014·33·1（41-46）

摘要：

目的尋求無創(chuàng)傷的且能自適應(yīng)信號(hào)變化的方法區(qū)分正常和異常的心音信號(hào)，為臨床診斷提供更簡捷的參考方法。方法本文以心音信號(hào)非線性時(shí)間序列最大Lyapunov指數(shù)為主線，根據(jù)心音信號(hào)不同階段特性的統(tǒng)一性，提出了對信號(hào)分階段進(jìn)行研究的方法。首先對7種具有代表性的正常和異常心音信號(hào)的S1、S2心音分別分3階段進(jìn)行相空間重構(gòu)，然后結(jié)合各階段求得的相空間重構(gòu)參數(shù)計(jì)算對應(yīng)的最大Lyapunov指數(shù)，最后對正常、異常心音信號(hào)最大Lyapunov指數(shù)均值進(jìn)行比較分析。結(jié)果正常S1心音信號(hào)的最大Lyapunov指數(shù)均值0.1450，遠(yuǎn)大于異常S1心音信號(hào)，正常S2心音信號(hào)的最大Lyapunov指數(shù)均值也比異常S2心音信號(hào)大很多。結(jié)論心音信號(hào)中確實(shí)存在混沌現(xiàn)象，且正常(健康)心臟運(yùn)動(dòng)到S1和S2階段的混沌程度要比異常(病態(tài))時(shí)高。

Objective To seek a way non-invasive and adaptive to differentiate the normal and abnormal heart sound signals in order to provide more valuable reference method for clinical diagnosis.Methods This paper made the largest Lyapunov exponent as the mainline.According to the unity of the whole signal in different stages，a method to study the characteristic in stage was proposed.First of all，we made phase space reconstitution for the seven typical normal and abnormal heart sound signals in S1 and S2.Then，we calculated the largest Lyapunov exponents according to the phase space reconstitution parameters.At last，we analyzed the mean values of the largest Lyapunov exponents.Results The mean value of the normal heart sound signals in S1 was 0.145，which was much larger than the abnormal ones，and the mean value of the normal heart sound signals in S2 was also larger than the abnormal ones.Conclusions There are chaotic characteristic in heart sound signals exactly and the degree of chaos in normal heart sound signals is higher than that in abnormal ones.

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