We aim to determine whether pectoral nerve block (PECS) performed after induction of anesthesia but before surgical incision results less opioid use in the post operative period compared with local infiltration alone in children undergoing Cardiac Implantable Electronic Device (CIED) surgery.

The current anaesthetic management of CIED surgery at Sickkids is local anaesthetic infiltration by the EP cardiologist or a Pectoral nerve block (PECS) on an ad-hoc basis depending on the anaesthesiologist on a case by case basis. It is not known whether one technique provides better post- operative pain control and fewer adverse events than the other. In either case, the patient receives opioids as required during and after the procedure. Patients typically go home with a prescription for opioids to be taken for the first few days after surgery.

The PECS block is a recognized effective anaesthetic technique used for both intraoperative and postoperative pain control in adult breast surgery, chest wall procedures as well as one case report for CIED implantation and a small series in paediatric cardiac surgery. The advantages of the PECS block in these surgical procedures includes improved analgesia and reduced opioid use.

The investigators plan to conduct an RCT with two groups.

Group 1 will receive a PECS block (using 0.8 ml/kg of 0.25% bupivacaine with epinephrine 1: 200000 divided in two equal volumes between the two planes) by the anaesthesiologist and local infiltration (up to 0.2 ml/kg of 0.25% bupivacaine with epinephrine 1:200000) by the surgeon.

Group 2 will receive local infiltration (up to 0.8 ml/kg 0.25 % bupivacaine with epinephrine 1:200000) by the surgeon alone.

Both groups will be given opioids as rescue analgesics as deemed necessary during their procedure and as rescue analgesia postoperatively, so that no patient will have untreated pain.

Inclusion Criteria:

• All patients 3-18 years undergoing CIED surgery in the chest

Exclusion Criteria:

• Children < 3 years of age at time of procedure as bupivacaine is not licensed for this age group.
• No parental or patient consent
• Allergy to bupivacaine
• Pregnancy or lactation
• Any condition or diagnosis, that could in the opinion of the Principal Investigator or delegate interfere with the participant's ability to comply with study instructions, might confound the interpretation of the study results, or put the participant at risk.

The nursing staff in the post anesthesia care unit, patient and outcome assessors will be blinded to the patient allocation.