| Popis: |
Reliable ECG classification can potentially lead to better detection methods and increase\ud accurate diagnosis of arrhythmia, thus improving quality of care. This thesis investigated the\ud use of two novel classification algorithms: CSVM and SIMCA, and assessed their\ud performance in classifying ECG beats. The project aimed to introduce a new way to\ud interactively support patient care in and out of the hospital and develop new classification\ud algorithms for arrhythmia detection and diagnosis. Wave (P-QRS-T) detection was performed\ud using the WFDB Software Package and multiresolution wavelets. Fourier and PCs were\ud selected as time-frequency features in the ECG signal; these provided the input to the\ud classifiers in the form of DFT and PCA coefficients. ECG beat classification was performed\ud using binary SVM. MSVM, CSVM, and SIMCA; these were subsequently used for\ud simultaneously classifying either four or six types of cardiac conditions. Binary SVM\ud classification with 100% accuracy was achieved when applied on feature-reduced ECG\ud signals from well-established databases using PCA. The CSVM algorithm and MSVM were\ud used to classify four ECG beat types: NORMAL, PVC, APC, and FUSION or PFUS; these\ud were from the MIT-BIH arrhythmia database (precordial lead group and limb lead II).\ud Different numbers of Fourier coefficients were considered in order to identify the optimal\ud number of features to be presented to the classifier. SMO was used to compute hyper-plane\ud parameters and threshold values for both MSVM and CSVM during the classifier training\ud phase. The best classification accuracy was achieved using fifty Fourier coefficients. With the\ud new CSVM classifier framework, accuracies of 99%, 100%, 98%, and 99% were obtained\ud using datasets from one, two, three, and four precordial leads, respectively. In addition, using\ud CSVM it was possible to successfully classify four types of ECG beat signals extracted from\ud limb lead simultaneously with 97% accuracy, a significant improvement on the 83% accuracy\ud achieved using the MSVM classification model. In addition, further analysis of the following\ud four beat types was made: NORMAL, PVC, SVPB, and FUSION. These signals were\ud obtained from the European ST-T Database. Accuracies between 86% and 94% were obtained\ud for MSVM and CSVM classification, respectively, using 100 Fourier coefficients for\ud reconstructing individual ECG beats. Further analysis presented an effective ECG arrhythmia\ud classification scheme consisting of PCA as a feature reduction method and a SIMCA\ud classifier to differentiate between either four or six different types of arrhythmia. In separate\ud studies, six and four types of beats (including NORMAL, PVC, APC, RBBB, LBBB, and\ud FUSION beats) with time domain features were extracted from the MIT-BIH arrhythmia\ud database and the St Petersburg INCART 12-lead Arrhythmia Database (incartdb) respectively.\ud Between 10 and 30 PCs, coefficients were selected for reconstructing individual ECG beats in\ud the feature selection phase. The average classification accuracy of the proposed scheme was\ud 98.61% and 97.78 % using the limb lead and precordial lead datasets, respectively. In addition,\ud using MSVM and SIMCA classifiers with four ECG beat types achieved an average\ud classification accuracy of 76.83% and 98.33% respectively. The effectiveness of the proposed\ud algorithms was finally confirmed by successfully classifying both the six beat and four beat\ud types of signal respectively with a high accuracy ratio. |
