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

We analyzed the mechanism of effects of intra-aortic balloon pumping using the pressure-volume relationship and ventriculoarterial coupling in the nor mal and failing hearts. Materials: In 12 anesthetized Holstein calves ( wei ght, 93 +/- 8 kg), the ventricular end-systolic and arterial elastances, pr essure-volume area, and external work were analyzed during steady-state con tractions with traditional hemodynamic parameters with intra-aortic balloon pumping-off and -on (1:1 synchronous ratio). An acute ischemic heart failu re was induced by injecting 10 mu m microspheres (4.2 +/- 1.8 x 10(7 .)100g left ventricular weight(-1)) into the left main coronary artery; all measu rements were repeated, Results: Intraaortic balloon pumping did not change hemodynamic parameters in the control. However, during heart failure, intra -aortic balloon pumping decreased the arterial elastance from 3.6 +/- 3.3 m m 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 ventriculoarteri al coupling ratio from 3.1 +/- 0.8 to 2.3 +/- 0.8, Intra-aortic balloon pum ping 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 mt to 1 37 +/- 37 mt and from 13.9 mm Hg to 12.8 mm Hg, respectively) with the left ward shift of the pressure-volume loop. Pressure-volume area decreased (fro m 914 +/- 284 mm Hg to 849 +/- 278 mm Hg mt) although stroke volume increas ed (from 21 +/- 6 mt to 24 +/- 6 mL). Conclusion: Reduction of the arterial elastance with intra-aortic balloon pumping improved the ventriculoarteria l coupling ratio and increased stroke volume. Leftward shift of the pressur e-volume loop resulted in the reduction of pressure-volume area, which sugg ests the conservation of the myocardial oxygen consumption.