Intervention description {11a}
pain
After obtaining written informed consent, all patients will be taught to assess pain using the visual analog scale (VAS; 0–100 mm). According to institutional standards, patients will be fasted for 6 h for solids and 2 h for fluids and receive oral premedication with midazolam 0.05–0.1 mg /kg if requested.Before the arrival of the patient in the operating room, a study nurse will open an opaque envelope and prepare the study medication (30 ml ropivacaine 0.5% for the intervention group and 30 ml sodium chloride 0.9% for the placebo group) according to the study randomization and hand it to the blinded anesthetist.Upon arrival at the operating room, standard monitoring (5-channel electrocardiogram, pulse oximetry (SpOA five-lumen central venous catheter will be inserted in the right subclavian or internal jugular vein, depending on the indication of a bicaval extracorporeal venous drainage for cardiopulmonary bypass. Immediately afterward, the ultrasound-guided PECS II block will be performed under aseptic conditions on the right hemithorax using the technique described by Blanco et al. [According to our institutional standards, a trans-esophageal echocardiographic probe will be inserted in all patients to control and assess cardiac function.All PECS II blocks will be performed under ultrasound guidance by five consultant anesthetists experienced in the technique (