What is the treatment for Tetralogy of Fallot (TOF)?

Treatment for Tetralogy of Fallot (TOF)

The treatment for Tetralogy of Fallot requires complete surgical repair, with timing and approach individualized based on patient age, symptoms, and anatomy, typically performed between 3-11 months of age for optimal outcomes. 1

Initial Assessment and Management

• Patients with TOF should be evaluated by a cardiologist with expertise in Adult Congenital Heart Disease (ACHD) at least annually 2
• Comprehensive echocardiographic imaging should be performed at a regional ACHD center to evaluate anatomy and hemodynamics 2
• Genetic screening for heritable causes (e.g., 22q11 deletion) should be offered to all patients 2

Surgical Management Based on Presentation

Unoperated Adults ("Pink Tetralogy")

• Patients with mild pulmonary obstruction and mild cyanosis may not be diagnosed until adulthood 2
• All unoperated or palliated adults should undergo formal evaluation at an ACHD center regarding suitability for complete repair 2

Symptomatic Neonates and Infants

• For symptomatic neonates <4kg with hypercyanotic spells or ductal-dependent pulmonary circulation:

  • Palliative procedure followed by complete repair at 6-12 months 3
  • Options include:
    • Modified Blalock-Taussig shunt (surgical systemic-to-pulmonary artery connection) 3
    • Right ventricular outflow tract (RVOT) stent (considered first-line palliative option) 1
    • Ductal stent or balloon pulmonary valvuloplasty 1

• For asymptomatic infants <4kg with threatened pulmonary artery isolation:

  • Palliative shunt followed by repair at 6-12 months 3

• For all other patients:

  • Complete repair after 6 months of age 3

Complete Surgical Repair

Complete repair consists of:

1. Ventricular septal defect (VSD) closure 2
2. Relief of right ventricular outflow tract (RVOT) obstruction, which may include: 2
   • Resection of infundibular stenosis (muscle)
   • Pulmonary valvotomy if valve is abnormal
   • Patch augmentation of RVOT
   • Transannular patch if pulmonary annulus is small
   • Placement of RV-to-pulmonary artery conduit if anomalous coronary artery crosses RVOT
3. Closure of patent foramen ovale or small atrial septal defect if present 2

Surgical Approach Options

• Transatrial approach: Used in approximately 10.6% of cases 4
• Transatrial-transpulmonary approach: Used in approximately 52.2% of cases 4
• Transatrial-transventricular approach: Used in approximately 31.8% of cases 4
• Homograft conduit: Used in approximately 5.3% of cases 4

Special Considerations

• For TOF with unilateral absence of pulmonary artery:

  • Pulmonary arterial Nakata index >200 mm²/m² and Z-score >-4 are criteria for successful complete repair 5
  • Most patients require palliative intervention as first step 5

• For TOF with small pulmonary arteries:

  • Collaborative approach between cardiac surgeons and interventional cardiologists is reasonable 2
  • May include preoperative stenting, intraoperative stenting, or intraoperative patch angioplasty 2

Post-Repair Management

Follow-up and Monitoring

• Annual follow-up with ACHD specialist 2
• Regular echocardiography and/or MRI performed by staff with ACHD expertise 2
• Periodic Holter monitoring individualized based on hemodynamics and clinical suspicion of arrhythmia 2
• Annual surveillance with history, ECG, assessment of RV function, and periodic exercise testing for patients with pacemakers/ICDs 2

Management of Post-Repair Complications

• Residual RVOT obstruction: Surgery indicated for: 2

  • Peak instantaneous gradient >50 mmHg
  • RV/LV pressure ratio >0.7
  • Progressive/severe RV dilatation with dysfunction

• Pulmonary regurgitation: Most common problem after repair 2

  • Surgical intervention indicated for symptomatic patients with severe pulmonary regurgitation or asymptomatic patients with signs of progressive/severe RV enlargement or dysfunction 2
  • Options include pulmonary valve replacement with heterograft, homograft, or mechanical valve 2

• Residual VSD: Intervention indicated for left-to-right shunt >1.5:1 2

  • Can be addressed via catheterization in appropriate anatomic locations 2

• Branch pulmonary artery stenosis: 2

  • Balloon angioplasty considered when RV pressure >50% of systemic level or with RV dysfunction
  • Also considered with unbalanced pulmonary blood flow >75%, 25%, or unexplained dyspnea

Pitfalls and Caveats

• Cardiomegaly on chest x-ray should prompt search for residual hemodynamic lesion (commonly pulmonary regurgitation) 2
• Development of arrhythmias should prompt search for underlying hemodynamic abnormality 2
• Coronary artery anatomy must be delineated before any intervention for RVOT to avoid interruption of important coronary vessels 2
• Diagnostic confusion may occur with double-outlet right ventricle, requiring careful exclusion of subaortic obstruction 2
• QRS duration ≥180 ms has been identified as a risk factor for sustained ventricular tachycardia and sudden cardiac death 2