RESUMO
OBJECTIVES: We tested the hypothesis that unloading the left ventricle with intra-aortic balloon counter-pulsation just prior to reperfusion provides infarct salvage compared with left ventricular (LV) unloading postreperfusion or reperfusion alone. BACKGROUND: Previous reports demonstrated infarct salvage with complete LV unloading with an LVAD prior to reperfusion; however, partial LV unloading using intra-aortic balloon pumps (IABPs) has not been evaluated. METHODS: Twenty-eight Yorkshire pigs were subjected to 1 hr of left anterior descending artery occlusion and 4 hr of reperfusion. An IABP was inserted and activated just prior to reperfusion (IABP-Pre), or 15 min after reperfusion (IABP-Post), or not at all (control). RESULTS: At baseline, the hemodynamic data were similar in the three groups. Myocardial infarct size expressed a percentage of zone at risk in control animals was 44.9% +/- 4.8%, IAPB-Pre group 20.9% +/- 5.1% (P < 0.05 compared to control), and IABP-Post group 33.2 +/- 6.1% (P = 0.16 vs. control group). There was a correlation between transcardiac endothelin-1 release at 15 min postreperfusion and infarct size (r = 0.59). CONCLUSION: LV unloading with an IABP prior to reperfusion reduces the extent of myocardial necrosis in hearts subjected to 1 hr of left anterior descending artery occlusion and 4 hr of reperfusion compared with either reperfusion alone or LV unloading after reperfusion. Inhibition of myocardial ET-1 release by LV unloading may be a significant mechanism of myocardial protection. These data suggest that in high-risk STEMI patients, IABP unloading prior to reperfusion might be more beneficial than IABP placement postreperfusion.