—This paper studies the cardiovascular response under heart failure condition supported by two types of ventricular assist devices (VADs): the positive displacement pump and the impeller pump. The cardiovascular system is modeled using the concentrated parameter method developed previously, by considering flow resistance, vessel elasticity and inertial effects of blood in individual conduit segments. The dynamic modeling of displacement and impeller pumps is represented by VAD inlet/outlet flow-rate changes. Results show that in each simulation, the diseased ventricle is effectively unloaded, and the physiological variables of arterial pressure and systemic flow are adequately maintained. The numerical model is under further development for more sophisticated studies of the interaction of the native cardiovascular system with VAD support and other cardiac prosthetic devices.