In this paper, an observer based sliding mode method is used to control the heart rhythm system. For this purpose, nonlinear and uncertain dynamics of a sick human heart are considered. The output of the three main parts of the heart is assumed to be the output of the controlled system and the electrical signal applied to the three main parts of the heart is also considered as the input vector. Hence the controller is designed using the MIMO sliding mode method. The control signals applied to the three points of the heart are determined in such a way that the electrocardiogram signal behaves desirable. An observer is also used to estimate unmeasurable state variables and uncertain functions of the heart. Continuous approximation method has been used to produce smooth control signals and remove chattering. The simulation results show the good performance of the proposed control system to control the heart rate behavior of a person with tachycardia disease. تفاصيل المقالة