A proposed model consisting of coupled ordinary differential equations is considered as a description of the heart’s action potential. System with time delay is used to recreate pathological behaviour in the heart’s conducting system such as slow/fast and slow/slow type of atrioventricular nodal reentrant tachycardia (AVNRT). In our study, introducing the feedback loops and couplings entails the creation of waves which can correspond to the re-entry waves occurring in the AVNRT. Our main aim is to study solutions of the given equations and take into consideration the influence of feedback and delays which occur in these pathological modes. Analytical results are illustrated by some numerical examples of the model dynamics.