Modelling the influence of cardiac motion on electrical excitation and the magnetocardiogram

Simulations of cardiac excitation were performed for cross sections of the human heart. To create computer models, magnetic resonance images (MRI) and magnetocardiograms (MCG) were acquired for a healthy human. The effect of geometry on properties of the magnetic field was investigated by running static simulations for two extreme cases - the relaxed state (diastole) and the contracted state (systole). The shape of the QRS complex and the T-wave substantially changes showing a weak QRS complex and elevated T-waves for the systolic geometry. In a second step we incorporated the dynamical aspect by implementing an interpolation algorithm to emulate cardiac contraction. The resulting simulated biosignals resembled the MCG showing a pronounced QRS complex as well as a T-wave of approx. the right amplitude. Hence, modelling cardiac excitation should also account for detailed geometry changes in order to quantiatively reproduce the shape of measured biosignals.