In this study, the investigators aim to compare the pressure gradient obtained by transesophageal echocardiography across the restrictive peri membranous VSD with direct catheter-based measurements of such gradient.

Ventricular septal defect is the most common congenital heart defect, occurring in 50% of all children with congenital heart disease (CHD) and in 20% as an isolated lesion.

The peri membranous (also called Para membranous or Cono ventricular) VSD is a communication adjacent to a portion of the membranous septum and the fibrous trigone of the heart, where the, and tricuspid valves are in fibrous continuity. These infracristal defects (below the crista supra- ventricularis) are the most common VSD subtype, accounting for approximately 80% of VSDs.

The ventricular septum can be well imaged by TEE. Starting from the standard transverse plane at 0° or so in the mi esophageal four-chamber (ME 4-Ch) view, the crux of the heart, the inlet septum and most of the muscular trabecular septum can be well seen from the AV valves down to the apex.

In this study, the investigators aim to compare the pressure gradient obtained by transesophageal echocardiography across the restrictive peri membranous VSD with direct catheter-based measurements of such gradient.

During the pre-anesthetic evaluation, demographic variables will be collected from each patient. ASA physical status and relevant comorbidities will be documented, and a recent echocardiogram will confirm the presence of VSD, its size, pressure gradient and estimated PAP.

Patients will be taken to the operating room and monitored with ASA standard monitors: ECG, NIBP, pulse oximetry, and capnography. Preoxygenation will be performed with FiO₂ adjusted to maintain normal oxygen saturation Anesthesia inhalational induction will be performed with sevoflurane until IV access is secured. Once IV access is established, transition to IV agents, fentanyl (1-2 mcg/kg), and rocuronium (0.8 mg/kg). Ventilation with oxygen and sevoflurane 1.5% for 3 min.

Direct laryngoscopy and intubation will be performed by an attending anesthesiologist (with more than two years of experience post-qualification) along with femoral arterial and venous line along with internal jugular central venous line insertion.

Using the previously inserted lines, the pressure gradient across VSD along with RVSP and PASP are directly measured using catheters under guidance of fluoroscopy along with the hemodynamics it was obtained with. This entails that this should be performed in a hybrid theatre otherwise, the confirmation of catheter placement by TEE should be done. TEE inserted in the same setup under the same hemodynamics, RV inflow outflow view obtained with best alignment for CWD interrogation and pressure gradient obtained along with its respective hemodynamics, this step is to be repeated with different personnel with different levels of experience. Care should be taken that both measurements should be taken with the same hemodynamics. TEE measurements of pressure gradient across the VSD are to be measured in the ME five chamber view and ME aorta long axis view as well.

The surgeon will then perform median sternotomy, cpb cannulation, VSD repair. Any considerable events during weaning from cpb shall be recorded along with the doses needed for vasopressors and inotropic support. TEE post bypass will be done by senior attending confirming VSD closure, RV function and PAP if possible.

Inclusion Criteria:

• Pediatric patients (6 months to 5 years).
• Patients with isolated peri-membranous VSD.
• Scheduled for surgical VSD closure.

Exclusion Criteria:

• Refusal of legal guardians.
• Patients with other types of VSD.
• Patients with pulmonary vascular diseases.
• Patients with unrestrictive VSD.
• Recent or active upper respiratory tract infection.
• Any relative or absolute contraindication for TEE.

The study will include pediatric patients aged 6 months to 5 years diagnosed with isolated peri membranous ventricular septal defect (VSD) who are scheduled for elective surgical VSD closure under general anesthesia. All patients will undergo intraoperative assessment of the pressure gradient across the VSD using both transesophageal echocardiography (TEE)-derived measurements and direct intraoperative measurement techniques.

Patients with other types of VSD, unrestrictive VSD, associated pulmonary vascular disease, recent or active upper respiratory tract infection, or any relative or absolute contraindication to TEE will be excluded. Informed consent will be obtained from legal guardians prior to enrollment.