An apparatus for assisting the cardiac function of a patient, comprising: an inflatable chamber operably positionable with respect to an aorta of the patient; a catheter connectable in fluid communication with the inflatable chamber; and a drive unit connectable to the catheter for selectively inflating and deflating the inflatable chamber in accordance with a control program, the control program including a process of determining time delays in the apparatus between the occurrence of a blood pressure in the patient at a point in time and the display of a pressure value corresponding to the blood pressure in the patient at the point in time on a blood pressure waveform, the process including: (a) determining a nominal time to issue an inflate command for inflating the inflatable chamber based on an ECG waveform of the patient's heartbeat; (b) adding a dither time interval to the nominal inflate command time to obtain an actual inflate command time; (c) determining a time to issue a deflate command for deflating the inflatable chamber based on the blood pressure waveform; (d) processing an inflation/deflation cycle in which the inflatable chamber is inflated at the actual inflate command time and deflated at the deflate command time (116,118); (e) acquiring blood pressure data from the patient during the inflation/deflation cycle (116, 119); (f) analyzing the acquired blood pressure data to determine a realization time at which the effects of inflating the inflatable chamber are realized on the blood pressure waveform (130, 132); and (g) determining a delay time between the actual inflate command time and the realization time (134,138, 140). an inflatable chamber operably positionable with respect to an aorta of the patient; a catheter connectable in fluid communication with the inflatable chamber; and a drive unit connectable to the catheter for selectively inflating and deflating the inflatable chamber in accordance with a control program, the control program including a process of determining time delays in the apparatus between the occurrence of a blood pressure in the patient at a point in time and the display of a pressure value corresponding to the blood pressure in the patient at the point in time on a blood pressure waveform, the process including: (a) determining a nominal time to issue an inflate command for inflating the inflatable chamber based on an ECG waveform of the patient's heartbeat; (b) adding a dither time interval to the nominal inflate command time to obtain an actual inflate command time; (c) determining a time to issue a deflate command for deflating the inflatable chamber based on the blood pressure waveform; (d) processing an inflation/deflation cycle in which the inflatable chamber is inflated at the actual inflate command time and deflated at the deflate command time (116,118); (e) acquiring blood pressure data from the patient during the inflation/deflation cycle (116, 119); (f) analyzing the acquired blood pressure data to determine a realization time at which the effects of inflating the inflatable chamber are realized on the blood pressure waveform (130, 132); and (g) determining a delay time between the actual inflate command time and the realization time (134,138, 140). (a) determining a nominal time to issue an inflate command for inflating the inflatable chamber based on an ECG waveform of the patient's heartbeat; (b) adding a dither time interval to the nominal inflate command time to obtain an actual inflate command time; (c) determining a time to issue a deflate command for deflating the inflatable chamber based on the blood pressure waveform; (d) processing an inflation/deflation cycle in which the inflatable chamber is inflated at the actual inflate command time and deflated at the deflate command time (116,118); (e) acquiring blood pressure data from the patient during the inflation/deflation cycle (116, 119); (f) analyzing the acquired blood pressure data to determine a realization time at which the effects of inflating the inflatable chamber are realized on the blood pressure waveform (130, 132); and (g) determining a delay time between the actual inflate command time and the realization time (134,138, 140).