The role of the human heart is to circulate the blood in order to provide every cell with vital nutritions via the cardiovascular system. Any irregularities might lead to the loss of life quality, and even sudden death. Therefore, stable circulation in the cardiovascular system is important. The steady and healthy circulation can be performed by the well-balanced harmonization between Excitation Contraction Coupling (ECC) and Mechano-electric feedback (MEF). In contrast to ECC, by which electrical activation of cardiac cells triggers the mechanical contraction of the heart, is well characterized, less is studied about the cellular mechanisms of MEF, where mechanical alterations in the heart influence back cardiac electrical activity. The goal of this study is to investigate the role of MEF in healthy cardiac cycles and in cardiac arrhythmia using human ventricular models. The effect of MEF is manifested by stretch-activated channels (SACs). The numerical formulation of SACs in terms of the fibre stretch of the myocardium is embedded in the modified Hill model that describes the myocardium as an electro-visco-active material [1]. In addition to the existing models of SACs in terms of the stretch along fibre direction [2], we propose models of SACs formulated in terms of the rate of stretch along fibre direction and the stretch along sheet direction. The influences of the three different models for SACs and different material properties on the regular cycles are analyzed by using the electrocardiogram and volume-time curves, and show that the each model of SACs leads to regionally varying reactions on the heart model. Moreover, we simulate ‘commotio cordis’ and ‘precordial thump’ and demonstrate that MEF take a vital role in fibrillation and defibrillation without the structural impairment in the heart. Furthermore, we study the role of MEF in premature ventricular contraction when the heart is hemodynamically disturbed.