چكيده به لاتين
Mathematical model of cardiac cell is an important tool for simulating the natural and unnatural behavior of cardiac cell. Today, Several electrophysiological models for simulating cardiac cell behavior has been proposed. Unfortunately these models are so complicated and spent a lot of time to run. For this reason researchers try to propose a model in order to decrease complexity of calculations. Studies has shown presence of restitution property in cardiac muscle cell is the main reason of many arrhythmias such as cardiac ventricular fibrillation that is one of the most dangerous heart disease. Restitution hypotheses has the main role in starting and continuing of ventricular fibrillation, and its modeling could take a significant step forward in the treatment of this disease. In this study, with using minimal model which consists of three state variables, restitution property is investigated. For this purpose, first, the parameters affecting the existence of restitution is determined, and then, the way these parameters effect on restitution curve is investigated. In order to drawing restitution curves, S1-S2 method and dynamical method has been used. For avoiding cardiac alternans and resolving it, it is tried to get the restitution curve flat with controlling models parameters. To verification the accuracy of results, examinations which are applied on the model, are compared with HR and LR-I model. Finally, the model chaotic behavior is examined, and with analyzing the proportion of time constants of model, the effectiveness of these proportions on chaotic behavior of model which its physiological mean is the presence of alternans in cardiac muscle, has been studied. With fulfilling the purpose of getting restitution curve flat, and therewith avoiding cardiac alternans which is a part of this study result, it is possible to avoid ventricular fibrillation.
Keywords: Ventricular action potential – Minimal model – Restitution property – modeling- Action potential duration
