What is the treatment for Tetralogy of Fallot?

Treatment of Tetralogy of Fallot

Complete surgical repair should be performed in infancy, typically between 3-6 months of age, consisting of VSD closure and relief of right ventricular outflow tract obstruction, achieving survival rates exceeding 98%. 1

Definitive Surgical Management

Primary Repair Approach

The definitive treatment is surgical repair addressing all four anatomic components simultaneously: [2, 2, 1

• VSD closure using a patch 1
• Relief of RVOT obstruction through resection of infundibular or sub-infundibular muscles and pulmonary valvotomy 2, 2
• Pulmonary valve management with valve-sparing techniques when anatomically feasible 1
• Extracardiac conduit placement when necessary 1, 3

Timing of Surgical Intervention

• Symptomatic neonates (hypercyanotic spells, ductal-dependent pulmonary circulation) weighing <4 kg should undergo palliative modified Blalock-Taussig shunt followed by complete repair at 6-12 months 4
• Asymptomatic patients weighing <4 kg with threatened pulmonary artery isolation should undergo BTS and repair at 6-12 months 4
• All other patients should undergo complete repair after 6 months of age 4
• Contemporary practice favors early complete repair at 3-6 months over staged palliation, with 30-year survival rates above 90% 1

Surgical Technique Selection

Two main approaches exist for RVOT reconstruction: 1

• Transannular patch repair remains the most commonly used approach when valve preservation is not feasible, though this invariably results in severe pulmonary regurgitation 2, 2, 1
• Transatrial approach with pulmonary valve preservation is associated with significantly lower early and late morbidity (P=0.009 for postoperative complications, P=0.022 for late adverse events) and should be employed when anatomically feasible 5
• RV to pulmonary artery conduit is used when other options are not feasible 1

Critical surgical consideration: Transannular patch is required in approximately 50-60% of primary repairs but only 13% when initial palliation allows pulmonary artery growth 6, 5

Preoperative Assessment

Required Imaging

Prior to surgery, the following imaging is essential: 1

• Cardiac MRI to evaluate detailed anatomy, ventricular function, valve function, hemodynamics, and tissue characterization with late gadolinium enhancement for prognostication 1
• Coronary angiography in patients with suspected anomalous coronary artery to delineate the course before RVOT interventions, as this is critical to avoid coronary compression during repair 2, 2
• Echocardiography by staff with expertise in congenital heart disease to confirm diagnosis and assess severity 7

Special Considerations

• Screen all patients for 22q11.2 deletion syndrome, as it is commonly associated with hypocalcemia and hypoparathyroidism that requires perioperative management 7
• Check ionized calcium, magnesium, parathyroid hormone, and creatinine levels in neonates to assess for hypocalcemia 7

Expected Surgical Outcomes

Contemporary surgical results demonstrate: 1

• Hospital mortality of 0-2.1% 1, 4
• 30-year survival >90% 1
• Mean RVOT gradient of 15 mm Hg postoperatively 1

Lifelong Surveillance Requirements

All patients require lifelong annual follow-up with an adult congenital heart disease specialist, as these patients are not "cured" and remain at significant risk for electrical and hemodynamic problems: 3, 8

Annual Evaluation Components

• History and physical examination by ACHD cardiologist 3
• 12-lead ECG to monitor for conduction abnormalities 3
• Comprehensive echocardiography assessing RV size/function, pulmonary regurgitation severity, residual RVOT obstruction, tricuspid regurgitation, and aortic root dilation 3
• Cardiac MRI for precise RV volume quantification and pulmonary regurgitation assessment 1, 3
• Periodic Holter monitoring with frequency individualized based on hemodynamics and clinical suspicion to detect exertional arrhythmias and prevent sudden cardiac death 3

Common Postoperative Complications

Nearly universal long-term complications include: 1

• Pulmonary regurgitation developing in 40-85% of patients 5-10 years after repair, leading to RV volume overload 2, 2
• RV systolic and diastolic dysfunction as a consequence of chronic volume overload 1
• LV dysfunction secondary to ventricular interdependence 1
• Decreased exercise capacity 1
• Ventricular arrhythmias as a risk factor for sudden death 2, 2
• Residual or recurrent RVOT obstruction 1
• Tricuspid regurgitation 1

Critical pitfall: The severity of pulmonary regurgitation is often underestimated by clinical examination and requires serial CMR imaging for accurate assessment 1

Reintervention Criteria

Pulmonary valve replacement is indicated for: 3

• Symptomatic patients with severe pulmonary regurgitation 3
• Asymptomatic patients with severe pulmonary stenosis or pulmonary regurgitation PLUS progressive or severe RV enlargement or dysfunction 3
• Residual RVOT obstruction with RV/LV pressure ratio >0.7 3

Reintervention Options

• Pulmonary valve replacement is the most common reintervention, with heterograft or homograft preferred 3
• Mechanical PVR only for patients requiring warfarin for other indications 3
• Percutaneous approaches should be performed before irreversible RV remodeling occurs but ideally after growth is completed to decrease need for repeated interventions 2, 2
• Cardiac catheterization allows simultaneous therapeutic interventions such as pulmonary artery balloon dilation and stent placement 2, 2

Arrhythmia Management

For documented sustained ventricular tachycardia or cardiac arrest: 3

• Implantable cardioverter defibrillator placement is mandatory 3
• Preoperative EP testing and catheter ablation in the catheterization laboratory 3

Critical Pitfalls to Avoid

• Transannular patch repair inevitably causes severe pulmonary regurgitation—valve-sparing techniques should be employed when anatomically feasible to minimize long-term RV volume overload 1
• Delayed recognition of RV dysfunction is common—serial CMR imaging is essential as clinical examination underestimates severity 1
• Avoid hypothermic circulatory arrest when possible, as individualized management based on patient size and anatomy optimizes outcomes 4
• Monitor for prolonged QT interval on ECG in patients with 22q11.2 deletion syndrome, as this predisposes to ventricular arrhythmias 7