An in-series ventricular assist system for assisting the circulation of blood in a patient is disclosed. A pumping bladder is disposed in the thoractic aorta of the patient and selected physiologic events relating to each heart beat are monitored by appropriate sensors. A gas handling subsystem inflates and deflates the pumping bladder in accordance with the detected physiologic events and a predetermined set of assist system parameters. A microprocessor evaluates the effects of inflation and deflation of the pumping bladder and the corresponding assistance on the patient for each heart beat. The microprocessor is operable to alter or adjust the assist system parameters for each subsequent heart beat in accordance with the effects of assistance of the pumping bladder on the patient. In the preferred embodiment, the assist system parameters which are set by the microprocessor for inflating and deflating the pumping bladder during the immediately preceding heart beat are used as the base line for making small adjustments in those parameters for the present heart beat. Alternatively, the microprocessor may be made operable to store the assist system parameters associated within an immediately preceding predetermined number of prior heart beats to compare the detected physiologic events from each of the stored preceding heart beats with those of the current heart beat.