What is the recommended treatment for a pediatric patient with Tetralogy of Fallot (TOF), a congenital heart defect?

Tetralogy of Fallot: Recommended Treatment

Complete surgical repair should be performed within the first year of life, addressing VSD closure and RVOT obstruction relief, with lifelong surveillance by an adult congenital heart disease specialist mandatory for all patients. 1

Surgical Management Strategy

Primary repair is the definitive treatment for Tetralogy of Fallot, with timing and approach determined by patient weight, symptoms, and anatomy. 1

Timing of Surgical Intervention

• Symptomatic infants (hypercyanotic spells, ductal-dependent pulmonary circulation) weighing <4 kg should undergo palliative modified Blalock-Taussig shunt followed by complete repair at 6-12 months 2
• Asymptomatic infants weighing <4 kg with threatened pulmonary artery isolation require BTS and repair at 6-12 months 2
• All other patients should undergo complete repair after 6 months of age, ideally within the first year of life 1, 2
• Delaying repair into adulthood results in chronic hypoxia complications including arrhythmias and ventricular dysfunction, though correction remains beneficial even in adults 3

Surgical Technique Components

The complete repair addresses all four anatomic components: 1

• VSD closure via patch 4
• RVOT obstruction relief through infundibular muscle resection and pulmonary valvotomy 1
• Transannular patch placement when pulmonary annulus is inadequate, though this universally results in severe pulmonary regurgitation 4
• RV-to-pulmonary artery conduit as alternative approach, which also leads to pulmonary regurgitation and RV volume overload 4

Surgical Outcomes

• Operative mortality for complete repair in infancy is <2% in contemporary series, with survival rates >98% 4
• 30-year survival exceeds 90% 4
• Long-term survival ranges from 68.5% to 90.5% depending on residual lesions 5

Lifelong Surveillance Requirements

Annual follow-up with an ACHD specialist is mandatory for life, as pulmonary regurgitation, RV dysfunction, and arrhythmias determine long-term morbidity and mortality. 1

Required Monitoring Components

• Clinical assessment focused on exercise tolerance, palpitations, dizziness, or syncope 1
• 12-lead ECG to monitor QRS duration—QRS ≥180 ms identifies high risk for sustained ventricular tachycardia and sudden cardiac death 1
• Comprehensive transthoracic echocardiography assessing RV size/function, pulmonary regurgitation severity, residual RVOT obstruction, tricuspid regurgitation, and aortic root dilation 1
• Cardiac MRI every 2-3 years for precise RV volume quantification and pulmonary regurgitation assessment, as echocardiography underestimates RV dysfunction 4, 1
• Periodic Holter monitoring with frequency individualized based on hemodynamics and clinical suspicion to detect ventricular arrhythmias 1
• Exercise testing to objectively assess functional capacity and detect exertional arrhythmias 1

Reintervention Criteria

Pulmonary valve replacement is required in 40-85% of patients 5-10 years after initial repair due to chronic pulmonary regurgitation causing progressive RV dilation and dysfunction. 1

Indications for Pulmonary Valve Replacement

• Symptomatic patients with severe pulmonary regurgitation require intervention 1
• Asymptomatic patients with severe pulmonary stenosis or pulmonary regurgitation PLUS progressive or severe RV enlargement or dysfunction require intervention 1
• Residual RVOT obstruction with RV/LV pressure ratio >0.7 or RV systolic pressure >50 mmHg requires intervention 1

Critical timing consideration: Intervention must occur before irreversible RV remodeling develops—delaying PVR until this threshold substantially worsens outcomes 1

Arrhythmia Management and Sudden Death Prevention

The incidence of sudden death in adult TOF patients is approximately 2.5% per decade, with ventricular tachycardia as the primary mechanism. 1

Risk Stratification and Intervention

• Documented sustained VT or cardiac arrest requires ICD placement 4, 1
• Inducible VT/VF or spontaneous sustained VT warrants ICD implantation if meaningful survival >1 year is expected 4, 1
• Worrisome symptoms (palpitations, dizziness, syncope) mandate immediate evaluation with hemodynamic catheterization and electrophysiology study 1
• Asymptomatic patients with nonsustained VT should undergo electrophysiology study to refine arrhythmia risk, with consideration for surgery if significant pulmonary regurgitation exists 1
• Recurrent sustained monomorphic VT or recurrent ICD shocks can be effectively treated with catheter ablation 4, 1
• Beta blockers should be used in patients with frequent or complex ventricular arrhythmias to reduce sudden cardiac arrest risk 4, 1

High-Risk Features Requiring Electrophysiology Study

• QRS duration ≥180 ms on ECG 1
• Unexplained syncope with at least moderate ventricular dysfunction or marked hypertrophy 4
• Severe ventricular dysfunction (LVEF <35%) with heart failure symptoms despite optimal medical therapy 4

Critical Management Pitfalls

• Never underestimate RV dysfunction even in asymptomatic patients—decompensation can occur under physiologic stress 1
• Never ignore QRS duration >180 ms—this substantially increases arrhythmia risk and mandates enhanced monitoring 1
• Never delay PVR until irreversible RV remodeling occurs—intervention should occur before this threshold 1
• Never assume repaired TOF patients are "normal"—residual hemodynamic abnormalities are nearly universal and affect tolerance to physiologic stress 4, 1
• Never use prophylactic class Ic antiarrhythmics (flecainide, propafenone) or amiodarone in asymptomatic patients with VA—this is potentially harmful 4

Special Populations

Pregnancy Considerations

• Pregnancy is contraindicated in patients with unrepaired TOF 1, 6
• After repair, pregnancy is usually well tolerated if no important hemodynamic residua exist, functional capacity is good, and RV function is no more than mildly depressed with maintained sinus rhythm 1
• Fetal risk: 4-6% risk of congenital heart disease in offspring; screening for 22q11.2 microdeletion should be performed before pregnancy 4, 1
• Fetal echocardiography should be offered in the second trimester 1

Perioperative Management for Non-Cardiac Surgery

• Maintain RV function by optimizing preload, reducing afterload, and supporting contractility 1
• Minimize increases in pulmonary vascular resistance by avoiding hypoxia, hypercarbia, acidosis, hypothermia, and excessive positive pressure ventilation 1
• Prevent tachycardia which reduces diastolic filling time and coronary perfusion 1
• Maintain systemic vascular resistance to prevent right-to-left shunting if residual ASD/VSD present 1
• Defibrillator must be immediately available with antiarrhythmic medications prepared 1