Ventriculoarterial coupling with intra-aortic balloon pump in acute ischemic heart failure

Purpose: We analyzed the mechanism of effects of intra-aortic balloon pumping using the pressure-volume relationship and ventriculoarterial coupling in the normal and failing hearts. Materials: In 12 anesthetized Holstein calves (weight, 94 ± 8 kg), the ventricular end-systolic and arterial elastances, pressure-volume area, and external work were analyzed during steady-state contractions with traditional hemodynamic parameters with intra-aortic balloon pumping-off and -on (1:1 synchronous ratio). An acute ischemic heart failure was induced by injecting 10 pm microspheres (4.2 ± 1.8 x 10⁷ · 100 g left ventricular weight-;) into the left main coronary artery; all measurements were repeated. Results: Intraaortic balloon pumping did not change hemodynamic parameters ill the control. However, during heart failure, intra-aortic balloon pumping decreased the arterial elastance from 3.6 ± 1.3 mm Hg to 2.9 ± 1.2 mm Hg · mL^-1 while not affecting the ventricular end-systolic elastance, this resulted in an improvement of the ventriculoarterial coupling ratio from 3.1 ± 0.8 to 2.3 ± 0.8. Intra- aortic balloon pumping decreased not only end-systolic pressure (from 69 ± 16 mm Hg to 64 ± 19 mm Hg) but end-diastolic volume and pressure (from 139 ± 38 mL to 137 ± 37 mL and from 13.9 mm Hg to 12.8 mm Hg, respectively) with the leftward shift of the pressure-volume loop. Pressure-volume area decreased (from 914 ± 284 mm Hg to 849 ± 278 mm Hg · mL) although stroke volume increased (from 21 ± 6 mL to 24 ± 6 mL). Conclusion: Reduction of the arterial elastance with intra-aortic balloon pumping improved the ventriculoarterial coupling ratio and increased stroke volume. Leftward shift of the pressure-volume loop resulted in the reduction of pressure-volume area, which suggests the conservation of the myocardial oxygen consumption.