Clinical techniques for the restoration of a failing heart are mainly based on the use of mechanical assist devices. In recent years, with the growing need for mechanical circulatory support, these devices have been shown to be a useful therapeutic tool, thanks to their intrinsic capability to unload the failing ventricle, allowing the heart to recover. Mechanical circulatory support systems (MCSS) require an accurate biomechanical characterization of the complex interaction that occurs between the patient and the mechanical support. A protocol for MCSS testing is proposed which takes into account several working conditions, in a modified test mock loop apparatus able to mimic various pathological conditions. Both physiological and pathological conditions can be replicated to show the actual efficacy of a MCSS device in correctly supporting a wide spectrum of ventricular conditions. The test bench is able to simulate the recovery of the pathological condition quite accurately, showing, at the same time, that this set up can be a reliable choice to characterize cardiac support devices. Thus the results of this experimentation can be useful to clinicians in forecasting the response of the heart affected by a cardiac disease and to set appropriate parameters for suitable assistance.