Differences in intracardiac signals on a realistic catheter geometry using mono- and bidomain models

The correct interpretation of intracardiac electrograms is a key issue in the diagnosis and treatment of cardiac arrhythmias. Recent studies have suggested a link between local effects of substrate modification and the morphology of catheter signals. Studying these situations goes beyond the scope of most simulation studies as geometrical parameters and electrode conductivity are not taken into account. In this work a catheter model with realistic dimensions and conductivities is studied, comparing two approaches for the computation of extracellular potentials. One uses a monodomain simulation followed by a forward calculation of extracellular potentials. The other one is based on bidomain calculations that consider the influence of a metal electrode on the spread of depolarization. Calculated signals are compared to in-vivo signals reported in literature. Both approaches are capable of reproducing the morphology of clinical signals. Amplitudes are in the mV range and therefore in the right order of magnitude. Bidomain signals reproduce the time course more accurately, which could be related to wavefront curvature. Changes in transmembrane voltage were found due to the presence of the catheter in the bidomain case. Concluding from this study, for most cases the monodomain simulation seems to be sufficient, however for the investigation of small-scale changes bidomain simulations better represent in-vivo data.