Competition of Two Stimulation Generators in Isolated Atrium

Abstract

Spontaneous parasystolic arrhythmia in a rabbit isolated right atrium are detected and analyzed. The experimental results areexplained by a model of two uncoupled oscillators acting in an excitable medium. The model describes a beat phenomenon that takesinto account a refractory period of the excitable medium. To get more insight into parasystolic effect additional experiments in isolatedatria with removed sinus nodes have been performed. The parasystolic dynamics has been artificially induced by using two externalelectrostimulators. It is shown that by spectral analysis of myocytes AP’s periods one can simply recover the characteristic periods ofexternal electrostimulators (in the case of artificially induced parasystolic dynamics) or intrinsic autonomic oscillatory sources (in thecase of spontaneous parasystolic dynamics). By matching the experimental myocytes AP’s dynamics to that obtained from the modelone can estimate the atrium refractory period. For parasystolic diagnose in real cardiac systems, we propose to use the spectral analysisof ECG. Ill. 5, bibl. 11 (in Lithuanian; summaries in Lithuanian, English and Russian).