Simulation and prediction of cardiotherapeutical phenomena from a pulsatile model coupled to the Guyton circulatory model.

In order to use simulation prediction for cardiotherapeutical purposes, the well-documented and physiologically validated circulatory Guyton model was coupled to a cardiac pulsatile model which comprises the hemodynamics of the four chambers including valvular effects, as well as the Hill, Frank-Starling, Laplace, and autonomic nervous system (ANS) effects. The program is written in the "C" language and available for everybody. The program system was submitted to validation and plausibility tests both as to the steady-state and the dynamic properties. Pressures, volumes and flows and other variables turned out to be compatible with published experimental and clinical recordings both under physiological and pathophysiological conditions. The results from the application to cardiac electrotherapy emphasize the importance of atrial contraction to ventricular filling, the adequate atrio-ventricular delay, the effect of impaired ventricular relaxation, and the significance of the choice of the adequate cardiac pacemaker, both with respect to the stimulation site and the adequate sensor controlling pacing rate. The simulation will be further developed, tested and applied for cardiological purposes.