Suppression Of Spiral Waves And Turbulence By Applying Electric Field

For almost half a century, vigorous developments in the nonlinear science researches have been made. People take further step for formation and application of the nonlinear phenomenon and obtain significant results. Pattern dynamics appeared as a transverse science form gradually along with the development of nonlinear science. Spiral wave is one kind of spatiotemporal pattern which is away from equilibrium in the nature and it’s break is harmful in many real systems shown in studies. Ventricular fibrillation can be induced in patients who have heart disease by the instability of spiral wave and leads them to die rapidly. Therefore, it is necessary for us to find several effective methods to prevent and control spiral wave in many practical problems including the treatment of ventricular fibrillation.Based on the pattern dynamics theory, this thesis is mainly about the nonlinear dynamics mechanism of arrhythmia in myocardial system and control strategy by applying different forms of electric field with modified FHN model. This thesis chapters and structure are arranged as follows:The pattern dynamics theory, reaction-diffusion system and the formation of spiral wave are introduced briefly in Chapter 1. Besides, several partial differential equation models which are used commonly in numerical simulation will also be given in this chapter.Chapter 2 shows control strategy of spiral wave and turbulence in two kinds of typical heterogeneous excitable media. The developed strategy by combining local-low-amplitude and high-frequency pacing (LHP) with radial electric field (REF) can terminate turbulence in excitable media with high degree of inhomogeneity, and the underlying mechanisms of successful control which are based on dispersion relation will be illustrated.Chapter 3 mainly studies the generation of spiral wave in a vortex electric field to suppress the turbulence and the meandering behavior of spiral by imposing a vortex electric field.Chapter 4 focuses on how to suppress turbulence and spiral wave by applying a rotating electric field to make wave emission from heterogeneities. The results obtained in numerical simulation are compared with the effect of pulse electric field and show the advantage of rotating electric field.In the Chapter 5, one makes a brief summary about this thesis, and prospects for future studies.In this thesis, a series of effective control strategies are put forward. Because the electric field is easily realized in the experiment, we hope these results can be verified in the experiment.