We report on a new tool for simulating cardiovascular physiology and pathophysiology with computer based equivalent electronic circuits (EEC) that protmotes qualitative as well as quantitative understanding about time-dependent physiological phenomena.The main advantage of this computer based simulation is its ability to demonstrate in real time transient cardiovascular changes and their progression to a steady-state.An EEC of the adult cardiovascular system with aortic stenosis was developed and used to simulate cardiovascular changes during rest, exercise and exertion syncope.