Inclusion Criteria:  90 adult patients of both sexes aged (21-60) scheduled for cardio-pulmonary bypass cardiac surgery (valve replacement) with midline sternotomy  Exclusion Criteria:  Patients' refusal. Cognitive impairment. History of drug abuse& chronic analgesic use History of allergy to local anesthetics. Emergency surgery Pre-existing major organ dysfunction including hepatic or renal failure, pulmonary insufficiency and left ventricular ejection fraction < 30% Known coagulopathy