This is a prospective double-blinded and randomised study involving patients undergoing cardiac surgery with median sternotomy, the effects on postoperative analgesia of a 48-hr continuous infusion of ropivacaine 2 mg.mL-1, at the rate of 4 mL.hr-1 through two catheters inserted at the lateral edges of the sternum will be studied, versus a control group in which normal saline will be infused in the same conditions.

Diverse methods for infusion of local anaesthetics after cardiac surgery have been proposed, but none of them provided high-level evidence of efficacy. The catheters studied here are designed for a surgical insertion before closure of the sternotomy, with the aim of infusing the drug the closest possible of the terminations of intercostal nerves.

Inclusion Criteria:

• Scheduled cardiac surgery.

Exclusion Criteria:

• - surgery in emergency
• thoracotomy
• cardiac graft
• redo
• pregnancy
• patient's refusal
• minor or adult under legal protection
• psychiatric ongoing disease
• addiction to opiates
• ongoing opiate treatment
• inability to use a PCA device
• respiratory insuffiency (Vital capacity or maximal expired volume per sec. < 50% of the expected value, or mean PAP > 50 mmHg)
• intra-aortic balloon
• severe renal insuffiency
• history of allergy or intolerance to: morphine, acetaminophen, bupivacaine.