This study examined the effects of inira-aortic balloon counterpulsation on left ventricular (LV) performance in 12 patients with coronary artery disease (CAD) using a multiwire camera and Ta178 (tVi'9.5 min). First-pass radionuclide angiograms were obtained at baseline, 1:1 and 1:2 balloon pumping at both 50% and 100% balloon inflation. The changes in LV ejection fraction (EF), cardiac output (CO by (hermodilution); peak filling rate (PFR, EDV/sec); puhnonary artery diastolic pressure (PAD); aortic systolic (AO) and augmented diastolic pressure (AD) are shown in the table. 100 50 Bastlint lil IS 1-1 IS? PAD 26±10 23±9 25±9 25±H 24±10 LVEF 37±15 42±10% 34±11 36±13 36±13 PFR 2.0±0.6 2.2±0.6 1.7±0.4 1.8±OJ 1.8±0.7 AO 109±12 99±J8 101±19 101±17 107±19 AD 66±11 112±12' 116±13< 95±15 93±12 P < O.OS vs 50% inflation The results show that 1:1 counterpulsation at 100% inflation produced improvement in both systolic and diastolic LV performance. These effects were not seen with other modes of counterpulsation. Thus, intra-aortic balloon counterpulsation results in improvement in systolic and diastolic LV performance in patients with CAD at a set up of 100% inflation and 1:1 counterpulsation. These effects are not seen with 1:2 counterpulsation or with 50% balloon inflation. The multiwire camera and short half-lived Ta-178 is ideally suited for these serial measurements at the bedside.