Inverse 3-D Heart Model for ECG Signal Simulation and Analysis

The most important health problem affecting large groups of people is related to the malfunction of the heart, usually caused by heart attack, rhythm disturbances and pathological degenerations. One of the main goals of health study is to predict these kinds of tragic events, and to identify the patients situated in the most dangerous states, to make it possible to apply a preventing therapy. This paper presents an event recognition study performed with ECG signal analysis and 3D heart model. The signal resource was a 192-electrode measurement (BSPM) database containing various malfunction cases like WPW syndrome, atrial and ventricular fibrillation and flutter. The preliminary ECG analyzer system (PAS) is based on detailed, a priori knowledge of human anatomy and physiology, developed by an ANN, tested and validated by physicians in clinical environment. In this study the PAS was used to obtain initial information on the site of origin of cardiac activation. The ANN output provides the initial heart model parameters. Then the BSPMs were simulated by the ECG generator unit, and the objective functions that assess the similarity between the measured and simulated signals were determined. The heart model parameters are adjusted with the aid of optimization algorithms, or physicians in certain cases. The simulation procedure is performed until the objective functions satisfy the given convergence criteria. Finally the parameters are validated. During the simulation, a parameter classification algorithm was applied to distinguish normal QRS complexes from abnormal ones, in order to determine the specific differences between the normal and abnormal parameter values. For normal cases the detection ratio was practically 100%, while in pathological cases, such as ventricular fibrillation, bypass tracts, the estimation accuracy varies from 90% to 98%. At present, the performance of personal computers does not make possible the real-time determination of parameter values. The practical application is possible only in case of strongly parallel systems.