ST VARIABILITY ASSESSMENT BASED ON COMPLEXITY FACTOR USING INDEPENDENT COMPONENT ANALYSIS, HILBERT TRANSFORM AND REGRESSION ANALYSIS

S. Thulasi Prasad, S. Varadarajan

Abstract: In recent days the computerized ECG has become the most effective and convenient diagnostic tool to identify cardiac diseases such as Myocardial Ischemia (MI). Among the Cardio vascular diseases (CVDs) the Myocardial Ischemia (MI) is one of the leading causes of heart attacks. The Myocardial Ischemia (MI) occurs due to the difficulties in the flow of the electrical impulses from SA node to bundle branches because of the abnormalities in the conduction system. Normally the ECG is used as a main diagnostic tool to identify the cardiac diseases. In order to obtain accurate information from ECG it is necessary to remove all the artifacts and extract the pure ECG from noise background. In this paper the removal of the artifacts is achieved with linear filtering and the extraction of the clean ECG signal is performed using Independent Component Analysis (ICA). After preprocessing and ECG extraction, the QRS complex of each beat is detected by using Hilbert Transform and simple threshold detection algorithm. Next the Instantaneous Heart Rate (IHR) from RR interval and Complexity Factor (CF) from time series ST segment are computed for each beat to form desired feature sets. Later a linear regression model is designed using Instantaneous heart rate (IHR) and ST segment Complexity Factors (STCFs) based on Linear Regression analysis. The proposed ICA-STCFR model is used to identify the ischemic beats from the test feature sets of ECG signal to assess the ST-Segment Variability (STV). The ECG data sets obtained from a local hospital were used to design and test the model. The evaluation parameters, Ischemic Intensity Factor (IIF), Ischemic Activity Factors (IAF) and Peak to Average Value (PAV) were used to evaluate the proposed method and compared with Wavelet Transform based method. The proposed ICA-STCFR was found to be yielding better results than WT-ST method.

Keywords: Myocardial Ischemia, ICA, HT, QRS Complex, RR interval, ST segments, IHR, STCF, Scatter-plo

DOI: https://doi.org/10.15623/ijret.2015.0410077