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.