A demand responsive physiological control system for use with a rotary blood pump； said system including a pump controller which is capable of controlling pump speed of said pump； said system further including a physiological controller, and wherein said physiological controller is adapted to analyse input data relating to physiological condition of a user of said pump； and wherein said physiological controller determines appropriate pumping speed and sends a speed control signal to said pump controller to adjust pump speed； said system further including a physiological state detector which provides said input data indicative of at least one physiological state of said user, in use, to said physiological controller.
