This study is to evaluate whether the administration of ultrasound-guided paravertebral block (PVB) after surgery would produce better postoperative pain control and fast postoperative recovery after Robotic cardiac surgery. Half of participants will receive PVB before surgery, while the other half will receive PVB at the end of surgery.

Ultrasound-guided PVB (either before surgery, or after surgery) is the standard postoperative pain management for Robotic cardiac surgery. This technique is to inject local anesthetic (numb medication) around nerve to decrease pain. But the optimal time of PVB is unknown.

The administration of PVB before surgery can help pain control during the surgery and after surgery. But the duration of PVB could be reduced because surgery itself can last 5-6 hrs.

The PVB after surgery will not provide pain control during surgery, but may provide longer pain control after surgery, and may help participants faster recovery after surgery.

Inclusion Criteria:

1. Age ≥ 18 yrs
2. ASA I-IV
3. Either gender

Exclusion Criteria:

1. Refusal to participate in the study

2. Age< 18 yrs

3. Contraindications to regional blockage including but not limited to:

   1. Patient refusal to regional blockade
   2. Infection at the site of needle insertion
   3. Systemic infection
   4. Bleeding diathesis or coagulopathy

Outcomes assessor will be blinded to study group