Pain is considered to be subjective, however, in children, it is believed to be felt rather than expressed because they often depend on the caregiver for their safety and well-being.

There is significant pain after thoracotomy surgery because of pleural and muscular damage, ribcage disruption, and intercostal nerve damage during surgery, which if not effectively managed, will lead to various systemic complications; pulmonary (atelectasis, pneumonia, and stasis of bronchial secretions), cardiovascular (increased oxygen consumption and tachycardia), musculoskeletal (muscle weakness), increased neurohormonal response and prolonged hospital stay. So adequate and sufficient post-operative analgesia for pediatric patients is mandatory.

The use of highly potent opioids for pediatric cardiothoracic anesthesia has gained widespread popularity during the last 20 years. In addition to the important advantage of hemodynamic stability, the large-dose opioid-based anesthetic techniques also blunt the stress response, However, large doses can cause oversedation, respiratory depression, and prolonged mechanical ventilation after surgery.

serratus anterior plane block guided by ultrasound was developed by Blanco et al, it is a novel technique in the management of pain following thoracic procedures.

Local anesthetic inserted into these planes will spread throughout the lateral chest wall, resulting in paresthesia of the T2 through T9 dermatomes of the anterolateral thorax. It became popular because it is much safer and easily administered than other alternative regional techniques such as thoracic paravertebral and thoracic epidural blocks.

The Erector Spinae Plane Block (ESPB) is also one of the recently known pain-controlling techniques used in pediatric cardiothoracic surgeries. It became popular because it is much safer and easily administered than other alternative regional techniques such as thoracic paravertebral and thoracic epidural blocks. Chin et al. documented the cadaveric spread of local anesthetic and noted that, radiologically, the local anesthetic spread extended 3 or 4 levels cranially and caudally from the site of injection.

These two blocks have been compared in a study by wang HJ et al in patients undergoing radical mastectomy.

To our knowledge, the comparison of serratus Plane Block versus erector spinae plane block in aortic coarctectomy operations in pediatric patients has not been investigated yet. This has encouraged the performance of the present study.

Inclusion Criteria:

• Age: 3 months-2 years.
• RACHS-1 score 3.
• Patients undergoing aortic coarctectomy operation with Lateral thoracotomy incision.

Exclusion Criteria:

• Patients whose parents or legal guardians refuse to participate.
• Preoperative mechanical ventilation.
• Preoperative inotropic drug infusion.
• Perioperative cardiopulmonary arrested patients.
• Patients undergoing aortic coarctectomy operation with midline sternotomy incision.
• History of mental retardation or delayed development that may interfere with pain intensity assessment.
• Known or suspected coagulopathy. (PT < 75% of control)
• Any congenital anomalies or any infection at the site of injection.
• Known or suspected allergy to any of the studied drugs.
• liver enzymes elevated more than the normal values.
• Renal function impairment (Creatinine value more than 1.2mg/dl or BUN more than 20mg/dl).
• Heart failure patients
• Redo patients and previous catheter dilatations