Inhalation of hydrogen gas protects against myocardial stunning and infarction in swine

Objectives. The present study was carried out to determine whether inhalation of hydrogen (H-2) gas protects myocardium against ischemia-reperfusion (I/R) injury in swine. Design. In anesthetized open-chest swine, myocardial stunning was produced by 12-minute occlusion of left anterior descending coronary artery (LAD) followed by 90-minute reperfusion in the first study. Group A inhaled 100% oxygen, and group B inhaled 2% H-2 plus 98% oxygen during ischemia and reperfusion. In the second study, myocardial infarction was produced by 40-minute occlusion of LAD followed by 120-minute reperfusion. Group C inhaled 100% oxygen during ischemia and reperfusion. Group D inhaled 2% H-2 plus 98% oxygen. Group E inhaled 4% H-2 plus 96% oxygen. Results. The change of segment shortening (%SS) from baseline at 90 minutes after reperfusion in group B was 74 +/- 13 (mean +/- SD) %, which was significantly higher than that in group A (48 +/- 15%). Myocardial infarct size in group E (32 +/- 10%), but not in group D (40 +/- 9%) was smaller than that in group C (46 +/- 6%). Conclusions. Inhalation of 2% H-2 gas improves myocardial stunning, and inhalation of 4% but not 2% H-2 gas reduces myocardial infarct size in swine.