Percutaneous trans-arterial angioplasty(PTA) is one of the peripheral arterial occlusive disease(PAOD) treatment. During and after PTA, ischemia-reperfusion pain is induced so proper analgesia is important. ischemia-reperfusion injury is due to reactive oxygen species. Dexmedetomidine has analgesic, sedative and anti oxidant effect. So the investigators research the patient's satisfaction that are given the dexmedetomidine during PTA procedure.