A Theoretical Study about Optimal Control Mechanisms of Cardiovascular System with Performance Function Involving Time Dependent Changes in Ventricular Ejection Pressure, Aortic Flow Rate and the Work of Ventricle

We challenged to explain how the cardiovascular system was organized and what was the control strategy by optimal control theory. The performance function minimized included the time dependent change of ventricular ejection pressure, time dependent change in the aortic flow rate and the work of ventricle. The reconstructed ventricular ejection pressure and aortic flow curves were comparable with actual measured data obtained from normal human subject and isolated canine left ventricle. The effects of changes in arterial resistance and aortic compliance on ventricular pressure and aortic flow were well reconstructed by present theory. The effects of changes by the end diastolic ventricular volume with stroke volume and the ejection duration on the aortic flow were well reproduced by present study. The behavior of the end ejection pressure could not be represented because of probable change in kinetics of Ca2+ionic and in dynamical properties of cardiac muscle fiber. The changes in weighting coefficients relating to the time dependent changes in ejection pressure and the work of ventricular affected not only the ejection pressure but also aortic flow.An optimal control theory with present performance function was useful to explain the total control strategy that cardiovascular system would be subjected. A limitation, however, existed that the optimal control theory could not describe. Those were the phenomenons that happening upon molecular level such as kinetic changes in Ca2+ions and individual cardiac muscle fiber.