Ketamine-lidocaine Versus Ketamine-fentanyl for Induction of Anesthesia in Patients With Left Ventricular Systolic Dysfunction Undergoing Elective Coronary Artery Bypass

Inclusion Criteria: * patients with coronary artery disease * with moderate to severe left ventricular dysfunction (ejection fraction \< 40%), * scheduled for elective CABG surgery Exclusion Criteria: * associated chronic stroke, TIA , carotid occlusive disease( due to abnormal vasomotor activity), patients with known neurological impairment (cerebral infarction , dementia ), significant carotid artery stenosis , * valvular heart disease, * persistent arrhythmias, * congestive cardiac failure, * on mechanical ventilation, * intra-aortic balloon pump, * emergency surgery, * and those with known allergy to any of the study's drugs, * severe systemic non-cardiac disease and * patients with baseline NIRS reading \< 60% * Patients with dementia or visual or auditory impairment