The Detection Technology Of T-wave Alternans Based On ARM

Frenquent occurrence of Sudden Cardiac Death (SCD) accidents cause human highly attention. SCD has the characteristics of chance and randomicity,it is important to interference and precaution in early. Malignant ventricular arrhythmias are the main reasons of leading to SCD. Lots of studies show that T-wave alternans exist in malignant ventricular arrhythmias. TWA is a cardiac electron variational phenomenon, it reflects that T-wave morphology, polarity and amplitude occur beat to beat alternans. TWA is an important index for ventricular arrhythmias prediction, it has great clinical value.Study emphases on this article is TWA algorithm, we have completed four aspects as follows;First is preprocessing for ECG signals. We use simple integer coefficient method, digital filtering and double-orthogonal wavelet function bior2.2 for ECG filtering process, combination of three methods can remove power interference, EMG interference and baseline drift. We can get ECG signals with clear characteristics.The second is ECG characteristics demarcation. Based on a-trous algorithm, Marr wavelet, which has the advantage of accurate positioning and simple calculation, is used to multilevel wavelet transform and demarcate ECG characteristic points.The third is the study of TWA detection algorithm. Make use of emulation database to describe poincare mapping shapes and TWA values. According to T-wave window and comparing with four modes for T-wave alignment, an improved T-wave window of TWA Poincare Mapping method is put forward. According to ECG characteristic points, we choose an improved T-wave window in every cardiac cycle, then average division about T-wave window and get 7 location points. We compose a series with consecutive 128-beat cycles. Difference values of series neighbor points compose a new series. Based on the new series, we can draw TWA Poincare Mapping. This series is divided into odd and even series. TWA amplitude Dt wais calculated and judged that TWA is exist or not. Then, make use of Spectrum Method and Poincare Mapping Method to simulate data files from American MIT/BIH standard arrhythmia database and European ST-T ECG database. We can get strong linear correlation between Dt wa and Vt wa , which are made the least square fit line. It proves that TWA Poincare Mapping has good feasibility.The fourth is the introduction for implementation scheme of TWA detection technique based on ARM. This implementation subject, which uses embedded operating system, includes two parts of hardware platform and software system. The core chip of system is S3C44B0X, which is based on ARM7TDMI,at the same time, we introduce hardware circuit, ARM ADS development environment and TWA detection programming flowchart.This article emphasis on Poincare Mapping for TWA detection algorithm, which is a method based on nonlinear dynamics theory system. T-wave window is improved to increase detection ratio. Poincare Mapping has the advantages of simple calculation, picture and convenient analysis. Nowadays, the relevant articles about TWA Poincare Mapping are not common in worldwide. The future study of TWA Poincare Mapping is very amplitude and has upper study value. We can make more study from Poincare Mapping pattern and parameter.