Waves in Two Dimensional Models of Myocardium
Normal heart function is directly connected with periodic propagation of excitation waves initiated by the pacemaker heart system. Electrophysiological experiments show that distortions in heart rhythm such as tachycardia are a precursor to ventricular fibrillation (see Fig. 5A and 5B in Chapter 1, Introduction). Ventricular fibrillation may occur in either already damaged or initially healthy hearts. The mechanisms of ventricular fibrillation are not fully understood. In current literature , monomorphic tachycardia is associated with stationary propagation of spiral excitation waves, while polymorphic tachycardia is thought to be due to nonstationary propagation. The breakup of a wavefront of a non-stationary propagating spiral wave obtained in computer simulation with tissue formed of AP models without Ca dynamics is considered fibrillation . Spiral waves were discovered during computer simulations . Their existence was confirmed, years later, in the course of physiological experiments  in 2D normal atrium cardiac tissue by properly applied premature stimulation.
KeywordsCardiac Tissue Excitable Medium Spiral Wave Action Potential Duration Restitution Normal Conduction Velocity
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