Simulation of high-resolution QRS complex using a ventricular model with a fractal conduction system. Effects of ischemia on high-frequency QRS potentials

Recent studies have analyzed the high-fidelity surface electrocardiographic signal, and efforts have been made to increase the diagnostic sensitivity of the electrocardiogram by observing its high-frequency components. It was found that the high-frequency (150--250-Hz) electrocardiogram appears to detect evidence of transient ischemia with greater sensitivity than visual inspection of the surface electrocardiogram. A finite-element three-dimensional model of the ventricles with a self-similar (fractal) conduction system has been introduced as a bridge to the understanding of electrocardiographic phenomena related to high-frequency potentials. The model was activated, and the dipole potential generated by adjacent activated and resting cells was calculated to obtain a high-resolution QRS complex. Normal and ischemic activation processes were simulated by regional reduction in conduction velocity. It was found that although the resulted low-frequency QRS complex was not significantly altered from normal conditions, the high-frequency components exhibited morphological changes similar to the ones observed during animal experiments and human studies. Based on the results obtained from the model, it can be concluded that these morphological changes can be attributed to a slowing of conduction velocity in the region of ischemia and that the model is adequate for meeting the challenges imposed by the requirements of high-frequency methods applied in clinical cardiology.