Detection and quntification of T-wave alternans within microvolt range

number: 
3193
إنجليزية
Degree: 
Author: 
Ahmed Saad Ibrahim
Supervisor: 
Dr. Ziad T. Al-Dahan
Dr. Abbas F. Al-Hashimi
year: 
2013
Abstract:

T wave alternans (TWA) is an electrocardiogram phenomenon illustrating inhomogeneity in cardiac electrical repolarization. It can be measured from the surface ECG as microvolt level beat-to-beat alternation in the shape, timing, or amplitude of the T wave. This phenomenon related to the mechanisms leading to ventricular arrhythmias. Moreover, positive TWA testing has been shown to predict cardiovascular mortality as well as sudden cardiac death (SCD) in diverse patient populations. The aim of the project is to detect and quantify T wave alternans in microvolt and present the methodological steps related to it. To achieve this, implementation of TWA analysis method is done. Preprocessing stages are necessary such as noise filtration, baseline wander cancellation, QRS detection, T wave extraction and alignment. The method that has been used in this work is the Modified Moving Average Method. The TWA magnitude is obtained by means of the absolute difference between even and odd heartbeat series averages computed at T-waves at the apex. This method performs well for different levels of TWA, noise, and sequence reversal, but it is sensitive to the alignment of the T-waves. Different ECG database have been used for this work which include Physionet/Challenge 2008 data base which contains simulated ECG with and without TWA and real ECG with TWA. Real ECG data without TWA has been recorded from normal person with no history of cardiac attack. Sensitivity and specificity test have been use for the evaluation of the result. For real ECG the sensitivity of the method was 0.792 while the specificity was 0.801. For the simulated ECG the sensitivity of the method was 0.867 while the specificity was 1.