When a brief current pulse is incident on excitable cells in cardiac and other nervous tissue, a change in phase of the cell's response is usually observed. In cardiac tissue, the cells are bared to external stimulation of generally positive currents, which depolarize the cells. In this paper an overview of the application of the phase resetting technique (PRT) in several cardiac models is presented. We discuss the effects of external stimuli in several cardiac cell models and we provide the phase transition curves (PTCs) resulted from the application of PRT with the Zhang et al. sinoatrial node model