In this work, we developed a closed loop model of the interaction between the heart and a cardiac pacemaker. The main novelty of our framework is the employment of a reaction-diffusion heart model, which could enhance the assessment of cardiac pacing. Additionally, we provided a specific hardware setup for the deployment of our framework. Our results show that the heart model reproduces the healthy activation sequence and is feasible for closed loop simulations. Furthermore, we successfully simulated the interaction between heart and pacemaker models during the insurgence of endless loop tachycardia. Finally, we believe that our closed loop system could be an effective supporting tool to evaluate the safety and efficacy of the therapeutic effect of cardiac pacemakers.