What is the best management approach for Tetralogy of Fallot (TOF)?

Management of Tetralogy of Fallot

Early complete surgical repair is the preferred approach for tetralogy of Fallot regardless of patient age, with timing and technique individualized based on anatomy, symptoms, and patient size. 1

Initial Diagnosis and Evaluation

• Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease, characterized by:

  • Ventricular septal defect (VSD)
  • Overriding aorta
  • Right ventricular outflow tract obstruction (RVOTO)
  • Right ventricular hypertrophy 2

• Diagnostic workup should include:

  • Echocardiography as first-line imaging to assess RVOT obstruction, VSD, pulmonary valve anatomy, and coronary artery anatomy 1
  • Cardiac MRI for accurate RV volume quantification and pulmonary regurgitation assessment 2, 1
  • Genetic screening for 22q11.2 microdeletion (present in approximately 15% of TOF patients) 2, 1

Surgical Management

Primary Repair Approach

• Complete surgical repair is indicated for most patients and should be performed by surgeons with specific expertise in congenital heart disease 2, 1
• Key components of surgical repair include:
  • VSD closure
  • Relief of RVOTO (infundibular resection and pulmonary valvotomy)
  • Possible RVOT or transannular patch placement 2

Timing of Repair

• Early complete repair (between 6-18 months of age) is now common practice with perioperative mortality of approximately 1% 2
• For symptomatic neonates weighing <4 kg (hypercyanotic spells, ductal-dependent pulmonary circulation):
  • Palliative modified Blalock-Taussig shunt followed by complete repair at 6-12 months 3
• For asymptomatic patients <4 kg with threatened pulmonary artery isolation:
  • Blalock-Taussig shunt followed by repair at 6-12 months 3
• For all other patients:
  • Complete repair after 6 months of age 3

Special Considerations

• Coronary artery anatomy must be assessed before surgical intervention, particularly for anomalous anterior descending coronary artery crossing the RVOT 2
• Valve-sparing approaches should be considered when possible to minimize future pulmonary regurgitation 2

Long-term Follow-up and Management of Complications

Monitoring Requirements

• Annual follow-up with a cardiologist experienced in adult congenital heart disease (ACHD) 2
• Regular assessment of:
  • RV function and size
  • Pulmonary valve function
  • RVOT gradient
  • QRS duration
  • Exercise capacity 1

Management of Common Complications

1. Pulmonary Regurgitation:

   • Pulmonary valve replacement is indicated for:
     • Severe pulmonary regurgitation with symptoms or decreased exercise tolerance 2
     • Moderate to severe RV dysfunction or enlargement 2
     • Development of symptomatic or sustained arrhythmias 2
     • Moderate to severe tricuspid regurgitation 2

2. Residual RVOT Obstruction:

   • Intervention recommended for:
     • Peak instantaneous echocardiography gradient >50 mm Hg 2
     • RV/LV pressure ratio >0.7 2
     • Progressive/severe RV dilatation with dysfunction 2, 1

3. Arrhythmias:

   • Electrophysiology testing for suspected arrhythmias 1
   • ICD implantation for documented sustained VT, VF, or cardiac arrest 2
   • Risk factors for sudden cardiac death include QRS duration >180 ms, RV dilation and dysfunction, history of syncope, older age at surgery, and residual hemodynamic lesions 2, 1

Pregnancy Considerations

• Comprehensive cardiovascular evaluation before pregnancy is recommended 1
• Pregnancy is generally well-tolerated if:
  • RV function is no more than mildly depressed
  • Sinus rhythm is maintained 1
• Risk of CHD in offspring is approximately 4-6% in the absence of 22q11 deletion 1

Common Pitfalls and Caveats

• Pulmonary regurgitation is often missed on clinical examination (short, quiet murmur) and may be overlooked on echocardiography 2
• Patients presenting with arrhythmias or cardiomegaly should undergo thorough evaluation for underlying hemodynamic abnormalities 2
• Prophylactic antiarrhythmic therapy with class Ic medications (flecainide, propafenone) or amiodarone is potentially harmful in patients with asymptomatic ventricular arrhythmias 2
• Timing of pulmonary valve replacement is critical - should be performed before irreversible RV remodeling occurs but ideally after growth is completed to reduce need for repeated interventions 2