A microcomputer-based control system for a pneumatically driven artificial heart is developed in which the control philosophy consists of P-wave synchronization and stabilization of atrial pressures at desired levels. A self-tuning algorithm based on pole-placement for a two-input, two-output PI-controller is proposed. An electrical analogue model of the circulatory system is used to illustrate the coupling effect of the systemic and pulmonary circulations by decoupling the whole system into subsystems.