抄録
An analysis of the circulatory equilibrium with natural and artificial heart including the afterload effects on cardiac output was proposed as an extension of the Guyton's theory not including the afterload effects, in which the equilibrium condition of circulation was obtained by equating cardiac output and venous return curves.
The results of this analysis showed that the venous pressure and cardiac output were given by equating the effective cardiac output curve, which was obtained as the points of intersection of the afterload characteristic curves and a peripheral conductance curve, and a venous return curve corresponding to a peripheral conductance. Then arterial pressure was given as a point of intersection of a peripheral conductance curve and the cardiac output obtained above. The circulatory autoregulation with applying an artificial heart to circulatory system was also analysed graphycally. Generally, the cardiac output sensitivity of an artificial heart to venous pressure changes was less greater than that of the natural heart, therefore the circulatory equilibrium during an artificial heart pumping was physiologically different from the natural heart. Farthermore, the resistance of the outflow cannula caused a depressive effect on cardiac output curve and an increased effect on venous pressure.
