Experimental off-pump coronary artery revascularization with adenosine-enhanced reperfusion

Objective: Although beating heart coronary artery bypass grafting has recen tly gained popularity, it eliminates the protective strategies tie, cardiop legia) developed for use in conventional cardiac operations. We recently in troduced the technique of perfusion-assisted direct coronary artery bypass to perfuse the grafted vessels during multivessel off-pump coronary artery bypass grafting. In the present study we tested the hypothesis that intraco ronary reperfusion with the cardioprotective agent adenosine during simulat ed perfusion-assisted direct coronary artery bypass attenuates reperfusion injury. Methods: In anesthetized dogs the heart was exposed, and the left anterior descending coronary artery was ligated for 75 minutes. Reperfusion was achi eved through a catheter in the left anterior descending coronary artery by means of a computer-controlled pump. Intracoronary left anterior descending coronary artery perfusion pressure was continuously matched to mean arteri al blood pressure. In one group (adenosine group) 10 mu mol/L adenosine was added to the blood during the first 30 minutes of reperfusion, whereas ano ther group (vehicle group) received a comparable volume of saline solution. Results: During the first 30 minutes of reperfusion, blood flow through the left anterior descending coronary artery was significantly greater (P < .0 5) in the adenosine group than in the vehicle group (150.6 <plus/minus> 21. 9 vs 50.2 +/- 11.3 mL/min at 15 minutes of reperfusion). Although there wer e no group differences in postischemic wall motion, infarct size was signif icantly smaller in the adenosine group than in the vehicle group (11.1% +/- 3.0% vs 28.0% +/- 4.0% of area at risk, P < .05). Myeloperoxidase activity in the necrotic tissue, an index of neutrophil accumulation, tended to be lower in the adenosine group than in the vehicle group (58.6 <plus/minus> 1 4.2 vs 91.0 +/- 21.6 Delta AbsUnits . min(-1) . g(-1) tissue). In isolated postischemic left anterior descending coronary artery rings, the maximal re laxation response to the endothelium-dependent vasodilator acetylcholine wa s significantly greater in the adenosine group than in the vehicle group (9 7.9% +/- 5.6% vs 64.7% +/- 6.5%, P < .05). Conclusion: This novel reperfusion strategy for off-pump coronary artery by pass grafting can be used not only in cases requiring multiple grafting but also to attenuate necrosis and endothelial dysfunction in acute evolving i nfarction.