There is disclosed a controller for controlling the inflation of a balloon in a balloon stent catheter system including (i) a transducer adapted to receive a source of intracoronary arterial pressure in a patients coronary artery and to provide arterial pressure waveform data indicative of the status of a patients cardiac cycle based upon the intracoronary arterial pressure, and (ii) an inflation pump adapted to inflate the balloon. The controller has a central processor programmed to cause the inflation pump to inflate the balloon in diastole, corresponding to about 55% to about 85% of a single R-R interval of the cardiac cycle, by an amount sufficient to achieve fixation of the stent at a target site in the coronary artery.
