On the role of optimization in the cardiovascular system

This essay discusses in a very simple manner several aspects of the meaning of optimization in general and, particularly, the role of optimization in relation to the work and action of the heart. Starting out with historical considerations the role of the properties of the heart as a pump, its relation to the arterial system, the problem of pulsatility and blood pressure and the role of time intervals and coronary perfusion is discussed. Mathematical methods permit the calculation of the time course of the cardiac ejection which, under certain constraints, minimizes the energy consumption of the heart. The saving of energy by this optimization compared with a nonoptimal ejection pattern is rather small--in the order of a few percent. It is therefore interesting and important to discuss the physiological meaning of small variations of the cost-effect function. It seems that unexplained phenomena like synchronization of heart beat and respiration have something to do with an optimization process. The most important conclusion is that any optimization has to be seen as a process related to the functioning of the organism as a whole.