In this paper, we propose an improvement of a dielectric elastomer actuator (DEA) based augmented aorta. The actuator is a multi-layered tubular DEA subject to the internal pressure of the blood. When activated in synchronisation with the heart, the DEA supplies energy and limits the load on the left ventricle. The improvement consists in implementing a constraint on the radial displacement of the actuator. This addition allows to increase the electromechanical stability of the device by avoiding snap-through of the material leading to irreversible breakdown. By increasing the stability of the device, it allows to reach higher activation voltages and thus, a higher energy. In order to help the design of this new actuator, we have developed an analytical model of the inflation of a tubular DEA. In addition to previous works, the new model takes into account the multi-layered structure of the device as well as the constraint on the radial displacement to obtain accurate characteristics of the DEA. After validation with specially design experiments, the modelling is used to study the influence of the radial limitation value on the performances of the DEA.