a trainer for cardiac surgery and other similar procedures includes an organ model such as a cardiac model , an animation network adapted to impart to the model a motion similar to the corresponding natural organ and a control device used to control the operation of the animation network . the cardiac model is made of two sections , an inner cast simulating the myocardium and an external shell simulating the pericardium . the model is made by forming an inner cast , dressing the cast and then forming the shell around the cast . the model is preferably made of silicon rubber .