Model-based Analysis and Interpretation of Human Intramyocardial Electrograms

The aim of this thesis was to develop and use both a schematic and a realistic anatomical heart model to simulate the propagation of electrical excitation and subsequent repolarization. The main goal was to interpret and analyze the morphology of intramyocardial electrograms. For this reason, a slab model approximating a human ventricular free wall and a biventricular model based on ultrafast computer tomography data from a patient were developed. The fiber architecture of the ventricular tissue was modeled using a rule-based approach. Transmural action potential heterogeneity was implemented using a parameterizable human membrane kinetic model. The progressing depolarization and repolarization processes in the myocardium could be identified as the cause of the formation of the typical signal morphology. Furthermore the impact of the intrinsic conduction system, several tissue parameters and simulation setups on the electrograms were analyzed. A special focus of this thesis was the investigation of fusion beats, which are the result of colliding depolarization wavefronts that originate from different sites of the ventricles and result in a characteristic alteration of the signal course. To compare the obtained simulation results with examination results, various sequences of intramyocardial electrograms were recorded from the aforementioned patient.