Free radical scavengers improve functional recovery of stunned myocardium in a model of surgical coronary revascularization

This study examined whether treatment with the oxygen free radical scavengers, superoxide dismutase and catalase, could improve functional recovery in hearts subjected to regional ischemia and global cardioplegic arrest. Regional left ventricular (LV) function was assessed in open chest pigs with sonomicrometry and micromanometry to calculate an index of regional work from the LV pressure-segment length relationship. After measuring baseline preischemic function, the left anterior descending artery was occluded, creating a region-at-risk in 20% of the LV mass. Cardiopulmonary bypass was begun 15 minutes after initiation of regional ischemia and was followed immediately by cardioplegic arrest for 45 minutes, after which time the coronary artery occluder was removed to simulate coronary revascularization. Starting just before removal of the aortic cross-clamp and continuing for the first 30 minutes of reflow, animals received an aortic root infusion of either superoxide dismutase (3600 U/kg) and catalase (20,000 U/kg) or a control saline solution infusion. In each group, seven animals were successfully weaned from cardiopulmonary bypass without inotropic support. After 2 hour of reperfusion, the recovery of baseline function in the region-at-risk was 44% ± 7% in the treated animals and 4% ± 13% in the untreated animals (p < 0.05). In this experimental model, oxygen free radical scavengers were effective in preserving functional recovery in regionally ischemic myocardium reperfused under conditions simulating surgical revascularization in the setting of acute myocardial ischemia.