Inclusion Criteria:  Subjects scheduled for cardiac surgery (CABG, CABG + single valve) involving primary median sternotomy and left-sided pleural chest tube Age 18-85 years of age BMI 18-50 kg/m2 Weight > 60 kg  Exclusion Criteria:  Left ventricular ejection fraction (LVEF) < 30% Preoperative, intraoperative, or immediate post-operative placement of intra-aortic balloon pump or deployment of extra-corporeal membrane oxygenation (ECMO) Inability to understand or speak English Allergy to bupivacaine or other amide local anesthetic Contraindication to peripheral nerve block (e.g. local infection, previous trauma to the block site) Chronic opioid consumption (daily oral morphine equivalent of >20 mg) in the past three months Severe pulmonary or hepatic disease Neurological deficit or disorder Suspected or known addiction to or abuse of illicit drug(s), prescription medicine(s), or alcohol within the past two years Uncontrolled anxiety, schizophrenia, or other severe psychiatric disorder