A patient who had had two coronary artery bypass grafts and an aneurysmectomy required intra-aortic balloon pump (IABP) assistance to allow discontinuation of cardiopulmonary bypass (CPBP). An indwelling electromagnetic flow probe on the ascending aorta was used to monitor IABP over the following 8 days of assistance. Stroke volume (SV), Cardiac output (CO), stroke work (SW), and ventricular afterload (VA) were measured directly. Recovery was indicated as the discrepancy between CO and SV on and off IABP decreased. VA depended upon the degree of augmentation. SW bore an incostant relationship to IABP.