What is the repair of Tetralogy of Fallot (TOF)?

From the Guidelines

Tetralogy of Fallot repair typically consists of ventricular septal defect closure and relief of right ventricular outflow tract obstruction, usually by placement of a transannular patch, which may result in severe pulmonary regurgitation and right ventricular volume overload. The repair of Tetralogy of Fallot (TOF) is a surgical procedure that aims to correct the four heart defects present in this congenital condition: ventricular septal defect, pulmonary stenosis, right ventricular hypertrophy, and overriding aorta [ 1 ]. The surgery is typically performed on infants or young children and involves closing the hole between the ventricles with a patch, removing muscle overgrowth that obstructs blood flow from the right ventricle, and widening the pulmonary valve and arteries to improve blood flow to the lungs.

Key Points

• The main pathologic basis of TOF is antero-cephalad deviation of the developing conal septum, which causes a malalignment type ventricular septal defect and right ventricular outflow tract obstruction [ 1 ].
• Definitive repair is generally performed in infancy with survival rates of > 98% in multiple series [ 1 ].
• After surgery, patients need lifelong cardiac follow-up as they may develop complications like pulmonary valve regurgitation, arrhythmias, or residual ventricular septal defects [ 1 ].
• The timing of repair depends on the severity of symptoms, but complete repair is usually performed within the first year of life to prevent long-term complications such as cyanosis, exercise intolerance, and right ventricular dysfunction [ 1 ].

Considerations

• The procedure is done through open-heart surgery requiring cardiopulmonary bypass.
• In some cases, a patch may be placed across the right ventricular outflow tract or an RV to pulmonary artery conduit may be used instead of a transannular patch, which may also result in pulmonary regurgitation and right ventricular volume overload [ 1 ].

From the Research

Repair of Tetralogy of Fallot (TOF)

The repair of Tetralogy of Fallot (TOF) is a surgical procedure that aims to correct the congenital heart defect. The key components of the repair include:

• Closure of the ventricular septal defect
• Alleviation of the pulmonary stenosis
• Removal of the pulmonary valve if it is stenotic and not well-developed, which may lead to severe pulmonary regurgitation as a sequela 2
• Pulmonary valve replacement may be indicated in the ensuing years if signs of damage to the right ventricle are proven 2

Surgical Approach

The surgical approach to TOF repair has evolved over the years, with different strategies being employed depending on the patient's age, size, and anatomy. Some studies suggest that:

• Early complete repair is beneficial, with some centers promoting total correction in neonates irrespective of anatomy and symptoms 3
• A management protocol focused on patient size, systemic arterial saturations, and anatomy can help optimize outcomes 3
• Palliative modified Blalock-Taussig shunt (BTS) may be used in symptomatic patients weighing less than 4 kg, followed by complete repair at 6 to 12 months 3
• Transannular patch and monocusp reconstruction may be used in some cases, with the goal of preserving right ventricular and pulmonary valve function 4

Outcomes

The outcomes of TOF repair have improved significantly over the years, with:

• Low perioperative and long-term mortality rates 4
• Excellent long-term results, with most patients remaining well and leading normal lives 5
• However, late morbidity and mortality can occur due to right ventricular dysfunction, exercise intolerance, arrhythmia, and sudden cardiac death 5
• Reintervention rates are substantial, with a pooled estimate of 2.26%/year 4