Preoperative and intraoperative exclusion criteria Preoperative exclusion criteria 1) urgent or emergent surgery, 2) left ventricle (LV) ejection fraction < 50%, 3) application of intraaortic balloon pump (IABP), 4) myocardial infarction, 5) neurologic deficit, 6) hepatic or renal impairment, 7) pacing, 8) inotropic medication, 9) neurologic deficit.