A theoretical analysis of temperature distribution on an artificial ventricular assist device is performed using three-dimensional finite element modelling. The model consists of 6000 solid elements representing all the ventricle components. In order to find out the maximum Joule's losses allowed for the motor design, the simulation is able to propose the temperature distribution in each ventricular component. The model is based on thermal-electrical analogy, allowing an equivalent thermal conductivity for composite material. Two modes of heat transfer (conduction and convection) are used in this model. Results show the temperature distribution in each component and particularly on the bag housing. Maximum temperature should not be over 41°C which is possible with a limit of 4 W motor Joule's losses