In recent several clinical trials, remote preconditioning showed very powerful myocardial protection. However, the myocardial protective effect by remote preconditioning was not evaluated on the patients undergoing off pump coronary artery bypass graft surgery (OPCAB).

The investigators hypothesized that the lower limb remote preconditioning could protect the myocardium during the OPCAB. In this study, the investigators will try to evaluate whether remote preconditioning could induce myocardial protection on the OPCAB patients.

In recent two clinical trials on the patients undergoing cardiac surgery, remote preconditioning showed very powerful myocardial protection by simple and safe procedures such as the brief inflation of pneumatic tourniquet on the upper or lower limb. However, despite these impressive results, the clinical studies are lacking yet. Moreover, two previous studies were done on the cardiac surgery with cardiopulmonary bypass. Considering different mechanism, level of myocardial injury and the increasing popularity of OPCAB, we need the clinical study on remote preconditioning with the OPCAB patients.

In this study, we will conduct randomized controlled clinical trials in which the remote preconditioning was induced by lower limb ischemia with double-blinded technique. Myocardial injury will be assessed by postoperative serum troponin I levels and they will be compared with those of control group.

Inclusion Criteria:

• Adult patients undergoing elective off pump coronary artery bypass graft surgery

Exclusion Criteria:

• unstable angina
• preoperative use of inotropics or mechanical assist device,
• left ventricular ejection fraction less than 30%,
• major combined operation such as aortic surgery or carotid endarterectomy,
• severe liver, renal and pulmonary disease,
• recent myocardial infarction (within 7 days),
• recent systemic infection or sepsis (within 7 days)
• peripheral vascular disease affecting lower limbs
• amputation of the lower limbs