- Spiral waves evolving in various excitable media are governed by similar reaction-diffusion mechanisms. They also have an important impact on human health conditions. Spiral waves of electrical excitation in the heart and their instabilities are involved in causing certain types of cardiac arrhythmia, such as ventricular tachycardia and fibrillations, which can potentially lead to sudden cardiac death. The Belousov-Zhabotinsky (BZ) reaction is one of the most popular model systems to study the dynamics of spiral waves experimentally, because of both its easy preparation and the convenient detection of the wave patterns occurring in this reaction. The results from this project are catagorized into 4 parts. First, We found proper initial concentrations of reagents of an improved version of the BZ reaction with pyrogallol for further studies on the wave dynamics. This BZ reaction does not produce bubbles which potentially perturb wave dynamics. Second, we discovered influence of the reagent concentrations on the dynamics of spiral waves in thin layers of the BZ reaction with pyrogallol. The wavelength and the wave period increase with the concentration of pyrogallol. In contrast, the wave speed decreases when the concentration of pyrogallol is increased. However, H2SO4 and NaBrO3 affect the wave propagation in opposite to pyrogallol. Third, we studied the effect of an obstacle on a spiral wave and elimiantion of the spiral wave pinned to the obstacle by electrical forcing. An obstacle repels a far spiral wave, however attracts a nearby wave. Once the spiral wave gets attached to the obstacle, its wavelength, wave period and wave speed increase with the obstacle size. The pinned spiral wave can be released by an applied electrical current whose density higher than a critical value. Furthermore, the critical current density increases with the obstacle size. Finally, we have started experiments to investigate the influence of obstacles on spiral waves in three-dimensional (3D) BZ media. Preliminary results show that a vertical straight tube lying through the center of the close-loop filament does not affect the lifetime of the scroll ring. Experiments on other situations in the 3D systems are in progress.