What is the recommended management for a toddler or preschool‑aged child with tetralogy of Fallot?

Management of Tetralogy of Fallot in Toddlers and Preschool Children

Complete surgical repair between 3-6 months of age is the definitive treatment for tetralogy of Fallot, achieving survival rates exceeding 98%, and any toddler or preschool-aged child who remains unrepaired or palliated should undergo immediate formal evaluation at an adult congenital heart disease (ACHD) center for suitability for complete repair. 1, 2

Primary Management Strategy by Clinical Presentation

For Previously Unrepaired or Palliated Children

• Immediate referral to an ACHD center is mandatory for any toddler or preschool child with unrepaired or palliated tetralogy of Fallot to determine suitability for complete surgical repair 1
• The definitive repair consists of VSD closure using a patch and relief of right ventricular outflow tract (RVOT) obstruction through resection of infundibular/sub-infundibular muscles and pulmonary valvotomy, with transannular patch placement if needed 1, 2
• Contemporary surgical mortality is 0-2.1% with 30-year survival exceeding 90%, making delayed repair still highly successful even in this age group 2, 3

For Previously Repaired Children

All children with repaired tetralogy require at least annual follow-up with a cardiologist who has expertise in ACHD, as postoperative complications develop progressively over years. 1

Essential Surveillance and Monitoring

Imaging Requirements

• Comprehensive echocardiographic imaging must be performed at an ACHD center to evaluate anatomy and hemodynamics, assessing for residual RVOT obstruction, pulmonary regurgitation severity, tricuspid regurgitation, RV pressure (via tricuspid regurgitant velocity), residual VSD, and aortic root dilation with AR 1
• Cardiac MRI is the reference standard for RV volume quantification and systolic function assessment, and should be used when echocardiography is inadequate or to precisely evaluate pulmonary regurgitation severity and pulmonary artery anatomy 1, 2
• MRI provides superior assessment of branch pulmonary arteries, which are commonly deficient on transthoracic echocardiography 1

Key Postoperative Complications to Monitor

The following complications develop in 40-85% of patients 5-10 years after repair and require systematic surveillance 1:

• Pulmonary regurgitation leading to progressive RV dilation and dysfunction, which is the most common problem encountered and a risk factor for ventricular arrhythmias, right heart failure, and sudden death 1
• Residual RVOT obstruction at the infundibulum, pulmonary valve, main pulmonary trunk, or branch pulmonary arteries 1
• RV dilation and dysfunction due to chronic pulmonary regurgitation, often with associated tricuspid regurgitation that begets further RV dilation 1, 2
• Arrhythmias including sustained ventricular tachycardia, AV block, atrial flutter, and atrial fibrillation 1
• Progressive aortic root dilation with AR, seen in 15% of adults late after repair due to intrinsic aortic abnormalities 1
• Residual VSD from partial patch dehiscence leading to LV volume overload 1

Indications for Reintervention

Pulmonary Valve Replacement (Most Common Reintervention)

Reoperation is indicated in the following scenarios 2:

• Symptomatic patients with moderate or greater pulmonary regurgitation and cardiovascular symptoms (Class I indication)
• Asymptomatic patients with moderate or greater pulmonary regurgitation PLUS progressive or severe RV enlargement or dysfunction (Class IIa indication)
• Severe pulmonary stenosis with residual RVOT obstruction and RV/LV pressure ratio >0.7

Timing is critical: PVR should be performed before irreversible RV remodeling occurs but ideally after growth is completed to decrease need for repeated interventions 1

Catheter-Based Interventions

Interventional catheterization at an ACHD center is reasonable for 1:

• Elimination of residual ASD or VSD with left-to-right shunt >1.5:1 if anatomically appropriate
• Dilation (with or without stent) of RVOT obstruction
• Elimination of residual shunts or aortopulmonary collateral vessels in patients with unexplained LV/RV dysfunction, fluid retention, chest pain, or cyanosis

Critical caveat: Coronary artery compression testing is mandatory before RV-to-PA conduit stenting or transcatheter valve placement, as coronary compression with balloon-expandable stent inflation is a major concern 1, 2

Genetic Screening and Counseling

• Screen all patients for 22q11.2 deletion (present in ~15% of TOF patients), as this has implications for autosomal dominant inheritance, early-onset psychiatric disease, and family planning 1, 4
• Arrange consultation with a geneticist before pregnancy or if a genetic syndrome is identified 1
• The familial recurrence risk is approximately 3%, rising to 4-6% for offspring of affected individuals without 22q11.2 deletion 4

Critical Pitfalls to Avoid

• Do not rely on clinical examination alone to assess pulmonary regurgitation severity, as it is frequently underestimated; serial cardiac MRI is essential for accurate assessment 2
• Do not delay evaluation for reintervention in children with progressive RV dilation, as irreversible RV remodeling can occur and worsen outcomes 1
• Recognize that transannular patch repair (the most common surgical approach) inevitably causes severe pulmonary regurgitation, making long-term surveillance mandatory 1, 2
• Branch pulmonary artery stenosis or hypoplasia may be missed on echocardiography and requires MRI or catheter angiography for complete assessment 1