Interconnection between the number of ectopic focuses and degree of chaoticity of ventricular fibrillation

Abstract

Electrical activity of a heart in ventricular fibrillation is registered on an electrocardiogram as chaotic alternating different in amplitude and duration of exaltations. For the quantitative analysis of these irregularities methods of mathematical modeling and chaos theory are widely used. The aim of the present investigation is application of mathematical modeling methods for studying interrelation between the degree of chaoticity of ventricular fibrillation and number of the ectopic focuses functioning in a myocardium. Electrical activity of a heart in ventricular fibrillation was modeled as a sum of N independent pulse streams with various amplitude-frequency and phase characteristics. Degree of chaoticity of electrical activity of a heart was estimated by entropy and phase portraits of fibrillar oscillations. Theoretical dependences between degree of chaoticity of ventricular fibrillation and number of pulse streams were calculated by computer modeling. Results of computer experiments were compared with those of real physiological experiments on rats and dogs. It was shown that degree of chaoticity of fibrillar oscillations is different in rats and dogs and depends on the number of the ectopic focuses functioning in a myocardium. For rats two-focal types of models of ventricular fibrillation were characteristic, for dogs - multifocal (4-5 focuses) types.