This randomized controlled clinical trial investigates the efficacy of the serratus posterior superior intercostal plane block (SPSIPB) in patients undergoing cardiac implantable electronic device (CIED) implantation. Participants will be randomized to receive either SPSIP block with local anesthetic or a sham procedure with saline injection. Pain intensity will be evaluated intraoperatively and at 3, 6, 12, and 24 hours postoperatively using the Visual Analog Scale (VAS). Secondary outcomes include sleep quality at 24 hours assessed with the Sleep Quality Numeric Rating Scale (SQ-NRS), and patient and clinician satisfaction assessed with a 5-point Likert scale. The study is designed as prospective, double-blind, and parallel-group, aiming to improve perioperative pain management in CIED procedures.

Cardiac implantable electronic device (CIED) implantation is a common procedure for the management of arrhythmias and prevention of sudden cardiac death. Although routinely performed under local anesthesia, patients may experience intraoperative and postoperative pain, which can affect hemodynamic stability, recovery, and satisfaction. Effective perioperative analgesia is therefore critical in this patient group, who often present with multiple comorbidities and advanced age. Conventional systemic analgesics may be insufficient or associated with side effects, highlighting the need for alternative approaches.

The serratus posterior superior intercostal plane block (SPSIPB) is a recently described regional anesthesia technique targeting the interfascial plane between the rhomboid major and serratus posterior superior muscles. Previous studies have shown its efficacy in thoracic, breast, clavicular, and minimally invasive cardiac surgeries. However, its role in the context of CIED implantation has not been systematically studied.

This study is designed as a prospective, double-blind, randomized controlled trial. A total of 60 patients scheduled for first-time CIED implantation will be randomized into two groups: the intervention group (SPSIPB with 30 mL 0.25% bupivacaine) and the control group (sham injection with 1 mL saline). All procedures will be performed under standard local anesthesia. The primary outcome is perioperative pain assessed by VAS intraoperatively and at 3, 6, 12, and 24 hours postoperatively. Secondary outcomes include postoperative sleep quality (SQ-NRS) and both patient and clinician satisfaction (5-point Likert scale). The trial will provide evidence regarding the potential of SPSIP block to improve perioperative analgesia and patient-centered outcomes in CIED implantation.

Inclusion Criteria:

• Adults ≥18 years of age
• Scheduled for first-time cardiac implantable electronic device (CIED) implantation (pacemaker or ICD)
• Able to provide written informed consent
• Normal coagulation profile
• No local infection at the planned block site

Exclusion Criteria:

• Severe heart failure (NYHA class IV)
• Morbid obesity (BMI >35 kg/m²)
• Known allergy to local anesthetics (e.g., bupivacaine)
• Coagulopathy or ongoing anticoagulant therapy contraindicating regional block
• An established history of chronic pain, or diagnosed sleep disorders requiring active treatment (e.g., obstructive sleep apnea syndrome, insomnia)
• Local infection at injection site
• Psychiatric or neurologic disorders interfering with pain/sleep assessment
• Revision or replacement CIED implantation (not first-time)

Participants, care providers, and outcome assessors will be blinded to group allocation. The block (bupivacaine or sham saline) will be prepared and administered by an anesthesiologist not involved in outcome assessment.