Role of percutaneous bypass in reducing infarct size after revascularization for acute coronary insufficiency

This study compares the effectiveness of percutaneous bypass (PB) with that of the intra-aortic balloon pump (IABP) in reducing infarct size and ischemic damage after revascularization for acute coronary occlusion. In 30 adult pigs, the second and third diagonal vessels were occluded with snares for 1 1/2 hours, followed by 1/2 hour of cardioplegic arrest and 3 hours of reperfusion with the snares released. During the period of coronary occlusion before the institution of cardiopulmonary bypass, 10 pigs were placed on PB, 10 pigs received IABP, and 10 others received no intervention (unmodified). Ischemic damage in the area at risk was assessed by echo wall motion scores (ranging from 4 indicating normal to -1 indicating dyskinesia), changes in myocardial tissue pH (delta pH) from preischemia, and the area of necrosis/area of risk (AN/AR) ratio. Hearts treated with the IABP had the highest wall motion scores (1.27 +/- 0.33 for unmodified versus 1.40 +/- 0.30 for PB versus 2.04 +/- 0.30 for IABP), the least change in pH values from preischemia (delta pH: 0.41 +/- 0.13 for unmodified versus 0.60 +/- 0.10 for PB versus 0.25 +/- 0.09 for IABP, p less than 0.05 for IABP versus PB), and the least amount of myocardial necrosis (AN/AR ratio: 73 +/- 4% for unmodified versus 43 +/- 2 for PB versus 27 +/- 4 for IABP, p less than 0.05 for PB and IABP versus unmodified and for IABP versus PB). Although the PB group experienced less myocardial necrosis than did the unmodified group, the most optimal recovery occurred in the IABP group.