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

Management of Tetralogy of Fallot

The management of Tetralogy of Fallot requires a staged approach with early complete surgical repair as the primary intervention, followed by lifelong surveillance for complications including arrhythmias, pulmonary valve dysfunction, and right ventricular abnormalities. 1, 2

Diagnosis and Initial Assessment

• Diagnostic Evaluation:

  • Echocardiography: First-line assessment to evaluate RVOT obstruction, pulmonary regurgitation, RV function, and VSD 2
  • Cardiac MRI: Gold standard for RV volume quantification and pulmonary regurgitant fraction measurement 2, 3
  • Cardiac catheterization: For direct pressure measurements when non-invasive tests are inconclusive 2
  • ECG: To assess for arrhythmias and QRS duration (>180 ms indicates risk for ventricular arrhythmias) 2

• Key Anatomical Features to Assess:

  • VSD type and size
  • Degree of RVOT obstruction
  • Pulmonary valve anatomy
  • Branch pulmonary artery anatomy
  • Coronary artery anatomy (to avoid interruption during surgery) 1, 2

Surgical Management

• Timing of Repair:

  • Complete repair is typically performed between 3-6 months of age 4, 5
  • For symptomatic neonates <4 kg (hypercyanotic spells, ductal-dependent pulmonary circulation): Initial palliative modified Blalock-Taussig shunt followed by complete repair at 6-12 months 6
  • For asymptomatic patients <4 kg with threatened pulmonary artery isolation: Blalock-Taussig shunt followed by repair at 6-12 months 6

• Surgical Approach:

  • Complete repair involves:
    • VSD closure
    • Relief of RVOT obstruction (infundibular muscle resection)
    • Pulmonary valvotomy or valve-sparing techniques when possible
    • Patch augmentation of RVOT/pulmonary arteries as needed 4

Long-term Follow-up and Management

• Regular Surveillance:

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

• Imaging Schedule:

  • Echocardiography at each visit
  • CMR every 2-3 years or when clinical status changes 2

• Arrhythmia Management:

  • Periodic Holter monitoring (individualized based on hemodynamics and clinical suspicion) 1
  • Electrophysiology testing for suspected arrhythmias 1
  • ICD implantation for documented sustained VT or cardiac arrest 1
  • Avoid class Ic antiarrhythmic medications and amiodarone in asymptomatic patients with VA 1, 2

Indications for Reintervention

• Pulmonary Valve Replacement:

  • Severe pulmonary regurgitation with symptoms
  • RV dilation/dysfunction
  • Exercise intolerance 2

• Branch Pulmonary Artery Intervention:

  • Stenosis causing unbalanced pulmonary blood flow 2

• RVOT Obstruction:

  • Peak instantaneous echocardiography gradient >50 mm Hg
  • RV/LV pressure ratio >0.7 2

Special Considerations

• Genetic Testing:

  • Screen for 22q11.2 microdeletion (present in many TOF patients)
  • Important for genetic counseling before pregnancy 1

• Pregnancy Management:

  • Comprehensive cardiovascular evaluation before pregnancy
  • Generally well-tolerated if RV function is no more than mildly depressed and sinus rhythm is maintained 1
  • High-risk antepartum care may be warranted 1
  • Risk of CHD in offspring is approximately 4-6% in the absence of 22q11 deletion 1

• Risk Factors for Sudden Cardiac Death:

  • QRS duration >180 ms
  • RV dilation and dysfunction
  • History of syncope
  • Older age at surgery
  • Residual hemodynamic lesions 1, 2

Common Pitfalls to Avoid

• Underestimation of pulmonary regurgitation by echocardiography (use multiple imaging modalities)
• Failure to recognize branch pulmonary artery stenosis
• Overlooking coronary artery anomalies that may affect RVOT interventions
• Misinterpreting RV dilation as primarily volume overload when residual RVOT obstruction may be contributing 2

The long-term survival rate for patients with repaired TOF is greater than 85%, though complications including pulmonary regurgitation, recurrent pulmonary stenosis, and ventricular arrhythmias require ongoing management throughout adulthood 4.