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

This study compares ketamine/fentanyl versus ketamine/lidocaine in term of their impact on cerebral perfusion during CABG. No prior data address these effects, and the goal is to identify the induction regimen that better preserves cerebral oxygenation.

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