The goal of this randomized double blind study is to evaluate the analgesic efficacy of Transversus Thoracis Muscle Plane Block in patients undergoing cardiac surgery with median sternotomy.

one group of participants will receive multimodal analgesia plus ultrasound-guided Transversus Thoracis Muscle Plane Block with ropivacaine 0.5 % after induction of general anesthesia, the other group will receive multimodal analgesia without a bloc.

The investigators want to know if participants who receive the Transversus Thoracis Muscle Plane Block with ropivacaine have less pain than participants who do not receive a block.

Participants who undergo elective cardiac surgery with median sternotomy are eligible. They will receive general anaesthesia with multimodal analgesia as is standard in our institution. For study purposes participants will be randomized in a double blinded fashion to receive a Transversus Thoracis Muscle Plane Block with 30 mL of ropivacaine 0.5 %, or no block. As the block is carried out after induction of general anesthesia the participants will not know to which group they are assigned.

all blocks will be carried out after induction of general anesthesia, under full sterile precautions, and with ultrasound guidance. multimodal analgesia intra- and postoperatively is standardized and consists of: sufentanil, ketamine, dexmedetomidine, dexamethasone, paracetamol, metamizole, IV morphine in ICU.

The investigators aim for fast track surgery, i.e. extubation either in the operating room or in ICU within the first 6 postoperative hours.

the primary outcome is postoperative opioid consumption over the first 24 h postoperatively, secondary outcomes are pain scores and opioid-related side effects. all outcomes will be assessed by blinded investigators.

Inclusion Criteria:

• • Informed consent

  • Major adult (≥ 18 years old)
  • Body weight ≥ 50 kg. 50 kg is the minimal weight to ensure that participants will not receive an overdose of local anesthetic (ropivacaine 3 mg/kg)
  • Primary cardiac surgery via a sternotomy approach
  • Planned for fast-track procedure (i.e. postoperative extubation time of maximum six hours)

Exclusion Criteria:

• • Participation in another study within the 30 days preceding and during the present study

  • Refusal and/or inability to understand or sign the informed consent
  • Emergency cardiac surgery
  • Previous cardiac surgery
  • Hypersensitivity or allergy to ropivacaine and other amide-class LA
  • History of chronic pain
  • History of substance abuse
  • Severe cardiac dysfunction (i.e. LVEF ≤ 35%)
  • Severe obesity (BMI > 40kg/m2)

syringes with the study drug will be prepared by a study nurse. the patient, investigators and all carers will be blinded