Determinants of cardiac function: simulation of a dynamic cardiac pump for physiology instruction.

A computer model is described that simulates the cardiac cycle of a mammalian heart. The model emphasizes the pressure-volume plot as a teaching tool to explain the behavior of the heart as a pump. It exhibits realistic responses to changes in preload, afterload, contractility, and heart rate while displaying time-dependent changes in pressure and volume in addition to the pressure versus volume plot. It differs from previous models by graphing these parameters on a beat-to-beat basis, allowing visualization of the dynamic adaptation of the pumping heart to various stimuli. A system diagram is also included to further promote student understanding of the physiology of cardiac function. The model is useful for teaching this topic to medical, graduate, or undergraduate students. It may also be used as a self-directed computer laboratory exercise.