Effect of Parenteral Alpha-Tocopherol in the Definitive Surgery of Tetralogy of Fallot

Change in Serum Malondialdehyde (MDA) Concentration (ng/mL)

Serum malondialdehyde (MDA), a biomarker of oxidative stress, will be measured at baseline (before surgery), 1 hour after surgery, and 8 hours after surgery to evaluate oxidative injury associated with cardiopulmonary bypass during Tetralogy of Fallot repair.

Time frame: Before surgery, 1 hour after surgery, and 8 hours after surgery

Change in Serum Lactate Concentration (mmol/L)

Serum lactate levels will be measured at baseline (before surgery), and at 1 hour, 6 hours, 12 hours, and 24 hours after surgery to evaluate tissue perfusion and metabolic response associated with cardiopulmonary bypass during Tetralogy of Fallot repair.

Time frame: Before surgery, 1 hour, 6 hours, 12 hours, and 24 hours after surgery

Myocardial Injury Score (Histopathology, Scale 0-3)

Myocardial tissue injury will be assessed from biopsy samples collected 15 minutes after release of the aortic cross-clamp. Injury will be graded on a histopathological scale ranging from 0 to 3, where 0 = no injury and 3 = severe injury. Higher scores indicate worse myocardial damage.

Time frame: 15 minutes after release of the aortic cross-clamp

Apoptotic Index (% of Apoptotic Cardiomyocytes)

The apoptotic index will be calculated from myocardial tissue samples collected 15 minutes after release of the aortic cross-clamp. Sections are stained with TUNEL and examined at 40× magnification across 6 hotspot areas. The index is expressed as the percentage of TUNEL-positive cardiomyocytes per 100 cardiomyocytes. The scale ranges from 0% (no apoptosis) to 100% (all cells apoptotic). Higher values indicate greater myocardial apoptosis.

Time frame: tissue sample is collected 15 minutes after releasing the aortic cross clamp

Duration of Mechanical Ventilation (hours)

Duration of postoperative mechanical ventilation will be recorded in hours.

Time frame: From end of surgery until extubation

anti-cTnI

Time frame: tissue sample is collected 15 minutes after releasing the aortic cross clamp

GPx expression

Time frame: tissue sample is collected 15 minutes after releasing the aortic cross clamp

Intensive Care Unit Length of Stay (days)

ICU length of stay will be recorded in days from ICU admission until ICU discharge.

Time frame: From ICU admission until ICU discharge, assessed up to 14 days

Hospital Length of Stay (days)

Hospital length of stay will be recorded in days from hospital admission until discharge.

Time frame: From hospital admission until hospital discharge, assessed up to 30 days

Vasoactive-Inotropic Score (VIS, Scale 0-X)

Vasoactive-Inotropic Score (VIS) will be calculated to quantify the amount of vasoactive support required after surgery. The VIS scale ranges from 0 to an open-ended maximum value; higher scores indicate greater need for vasoactive support and worse hemodynamic status.

Time frame: First 24 hours after surgery