The interrelationship of factors controlling cardiac output

Our understanding of the mechanics of circulation may be broadened by testing old and new concepts on a new hydraulic model made possible by a unique pump which resulted from the evolution of open heart surgical equipment. Findings in human physiology which have corollaries in the model can be analyzed more easily in the model, with the resulting conclusions transferable with reasonable validity. Factors thought to control cardiac output were tested. The results indicate that there are two separate and distinct sets of control factors, with only one set being operative at a time. It is the set that is potentially limiting cardiac output the most that is the determinant at any time. Past paradoxes in our perception of human circulatory physiology are accommodated by the resulting concept.