Effects of timing on ventriculoarterial coupling and mechanical efficiency during intraaortic balloon pumping

To evaluate the effects of deflation timing of an intraaortic balloon (IAB) on ventriculoarterial (VA) coupling and left ventricular (LV) mechanics, we assessed contractility: Emax (mmHg/ml); VA coupling: Ea/Ees; myocardial oxygen consumption: LV pressure-volume area (PVA); and energy efficiency: external work (EW)/PVA during IAB pumping, using four different timing intervals of IAB deflation in eight dogs weighing 19.8 +/- 3.8 kg. In the conventional timing group (G-conv), the IAB was deflated before LV systole. In the real time group (G-1, 2, 3), the IAB was deflated during isovolumic contraction (ICP), and the group was subdivided into three groups based on time of deflation: G-1 at the onset of ICP, G-2 at the midpoint of ICP, and G-3 at the end of ICP. Percent changes in values with IAB compared to those without assist were calculated. Based on the results, IAB deflation during ICP reduces LV end-systolic pressure and significantly optimizes VA coupling and LV efficiency during IAB support, compared with conventional timing.