The goal of this clinical trial is to evaluate the analgesic effect of locoregional anaesthesia, specifically the interpectoral pectoserratus plane (IPP-PSP) block, in comparison to a placebo (sham block) after Aortic Valve Replacement via Right Anterior Minithoracotomy (AVR-RAT). The main question the trial aims to answer is: Can the IPP-PSP block effectively reduce opioid consumption within the first 48 hours after AVR-RAT surgery? The purpose is to understand the impact of the IPP-PSP block on postoperative pain. Therefore, the aim is to investigate the influence of the IPP-PSP block on the amount of pain medication administered during the patients' first 48 hours after surgery.

Participants, who are scheduled for AVR-RAT surgery, will be randomly assigned to receive either the IPP-PSP block or the sham block. Researchers will compare opioid consumption among other outcomes, including differences in pain scores, incidence of nausea and vomiting, quality of recovery, quality of life, and the length of hospital stay between the two groups.

Patients will be monitored during their hospitalization, and a follow-up phone call will be conducted 30 days after surgery.

This clinical trial aims to evaluate the analgesic effect of an interpectoral-pectoserratus plane (IPP-PSP) block compared to a placebo (sham block) in patients undergoing aortic valve replacement via right anterior minithoracotomy (AVR-RAT). The primary objective is to determine whether the IPP-PSP block effectively reduces opioid consumption during the first 28 hours post-surgery.

The trial is designed as a single-center, prospective, double-blind, randomized controlled superiority trial. It will enroll adult patients aged 18 years or older who are scheduled for minimally invasive AVR-RAT and meet specific inclusion criteria. Exclusion criteria are established to ensure the safety and integrity of the trial.

Patients undergoing minimally invasive AVR-RAT will be randomly assigned to either the IPP-PSP block group or the sham block group.

The primary endpoint of the trial is the cumulative opioid consumption (in oral morphine milligram equivalents (OMEs)) within the first 48 postoperative hours after completion of the surgical procedure. Secondary outcomes include the number of episodes of postoperative pain, time to need for rescue medication, incidence of respiratory complications, PaCO2 levels, postsurgical recovery, episodes of postoperative nausea and vomiting, time to extubation in the Intensive Care Unit (ICU), ICU length of stay, hospital length of stay, quality of life, number of days alive and at home after surgery, and vital status at 30 days post-operative.

The trial aims to enroll a total of 144 patients, with 72 patients randomized into each group. Blinding will be implemented, meaning neither the participant, anesthesiologist, study nurse, surgeon, nor the doctors and nurses in the Intensive Care Unit will know the participant's group assignment.

The anesthesia and monitoring proceed as usual for such procedures. After the anesthesiologist administered the IPP-PSP block or a placebo at the end of the procedure, the participant will be transferred to the ICU. During the hospital stay, they will be regularly asked to assess their pain level, and additional pain relief will be administered, if necessary.

To assess quality of recovery and quality of life differences between groups, participants will complete two questionnaires the day before surgery. A recovery questionnaire will be completed at three time points post-surgery (day 1, day 2, and day 7 after the surgery). Participants will be involved in the trial for a total of 31 days, with follow-up during hospitalization and a follow-up phone call 30 days post-surgery.

Inclusion Criteria:

• Adult patients (18 years of age or older);
• Patients scheduled for minimally invasive aortic valve replacement via right anterior minithoracotomy;
• Patients with American Society of Anesthesiologists (ASA) physical status classification II, III or IV;
• Patients with European System for Cardiac Operative Risk Evaluation (EuroSCORE) 2 ≤ 4%;
• Patient has given written, free and informed consent.

Exclusion Criteria:

• BMI > 35;
• Patients under legal protection (curatorship, guardianship);
• Patients subject to a legal protection measure;
• An adult who is incapable or unable to give consent;
• Patients requiring emergency surgery within 24 hours;
• Chronic opioid use (> 3 administrations per week or continuous transdermal therapy, longer than the last 3 months);
• Patients known with chronic pain;
• Patients known with an allergy to levobupivacaine or drugs used as standard of care, including amongst others piritramide, dexamethasone, propofol, remifentanil, rocuronium, acetaminophen, ondansetron;
• Patients who receive medication that could possibly interact with levobupivacaine (mexiletine, ketoconazole, theophylline);
• Patients who took monoamine oxidase (MAO) inhibitors within the last 2 weeks before surgery;
• Patients with chronic renal failure (dialysis dependent, estimated glomerular filtration rate (eGFR) < 30 ml.min-1.(1,73 m²)-1) ;
• Patients with severe hepatic impairment (Model for End-Stage Liver Disease (MELD) score ≥ 20);
• Patients with preoperative cognitive dysfunction (Mini Mental State Examination (MMSE) score < 24);
• Patients with uncontrolled epilepsy;
• Patients with severe arterial hypotension (Systolic Arterial Pressure (SAP) < 90 mmHg, cardiogenic shock);
• Patients who simultaneously participate in another interventional clinical trial;
• Soft tissue infection in the area of the procedure;
• Patients who are pregnant, parturient or breast-feeding women;
• Patients who are unable to sufficiently speak and write in the Dutch language.

Neither the participant, anesthesiologist, study nurse, surgeon, nor the doctors and nurses in the Intensive Care Unit will know the participant's group assignment.