RESUMO
This study analyses forward problem of electrocardiology. Premature beats originated from subepicardial layer of myocardium were simulated in order to analyse their shape dependence on the site of origin. The equation governing the propagation of the electrical wave through human thorax together with transition and boundary conditions is derived under the clearly stated simplifying assumptions. The weak formulation of the forward problem of electrocardiology is introduced, too. The Galerkin method as a convenient tool for looking for the numerical solution is mentioned and its practical implementation--finite element method--then used in order to obtain numerical results. The obtained results were presented in the form of isopotential maps and compared with actually measured body surface isopotential maps of the depolarization phase. The parameters of the model were then optimalized in accordance with the measured data. In spite of the lack of quantitative data the model has proved that the presented method was able to be used for the simulation studies of ventricular ectopic beats. It was shown that only a small difference between the site of beat origin can be well distinguished on the simulated body surface maps. (Fig. 3, Ref. 3.)