Simulated experience was performed through a computational haemodynamic fluid-structure solution, with the implementation of a mechanical bio-pump as a functional element of a ventricular assistance device, in which the mechanical dynamics of latissimus dorsi muscle is represented. The influence of chamber geometry and constituent material parameters is evaluated upon the pumping functionality. By analysis of haemodynamic variables, it is found that geometry and elasticity are parameters influencing the determination of the pump outflow. In conclusion, the computational haemodynamic model helps evaluate the mechanical behaviour of the functional cardiac assist device through haemodynamic variables.