Simulation of catecholamine action in an improved electrical model

A further development of an electrical model of circulation is presented. The progress consists in: (1) the ventricles are represented as a changing capacity; (2) a constant amount of charge is re-circulating in the system; (3) the contractility of the heart can be varied; (4) the valves are represented by relays, and (5) the pulse wave velocity can be represented. Catecholamine action is studied by changing the heart rate, contractility, elastic resistance and peripheral resistance; the influence on systolic, diastolic pulse pressure and flow pulse in different parts of the arterial system is measured. In the discussion the importance of the concept of deformation-capacity-internal surface of the ventricles for the understanding of the cardiovascular system as a unity is stressed.