What is the approach to managing Tetralogy of Fallot (TOF)?

Management Approach to Tetralogy of Fallot

All patients with repaired Tetralogy of Fallot require lifelong annual follow-up with an adult congenital heart disease (ACHD) specialist, with comprehensive imaging to monitor for pulmonary regurgitation, RV dysfunction, and arrhythmias—the primary determinants of long-term morbidity and mortality. 1

Initial Surgical Management Strategy

Timing and Approach for Primary Repair

Complete surgical repair should be performed after 6 months of age in most patients, with earlier palliation reserved only for specific high-risk scenarios. 2

• Symptomatic neonates (hypercyanotic spells, ductal-dependent pulmonary circulation) weighing <4 kg should undergo modified Blalock-Taussig shunt (BTS) followed by complete repair at 6-12 months 2
• Asymptomatic patients weighing <4 kg with threatened pulmonary artery isolation require BTS and delayed repair at 6-12 months 2
• All other patients should proceed directly to complete repair after 6 months of age, avoiding the need for circulatory arrest and minimizing morbidity 2, 3

This staged approach achieves mortality rates of approximately 2% with only 3% requiring reoperation after complete repair, compared to higher morbidity with universal neonatal repair 2

Components of Complete Surgical Repair

The operation addresses all four anatomic components simultaneously 1:

• VSD closure using direct suture or patch technique 1
• RVOT obstruction relief through resection of infundibular stenosis (muscle bundles) 1
• Pulmonary valve management with preservation whenever possible; transannular patch placement when annulus is severely hypoplastic 1
• Extracardiac conduit placement from RV to pulmonary artery only when anomalous coronary artery crosses the RVOT 1
• PFO/small ASD closure to prevent paradoxical embolism 1

Critical pitfall: Always obtain coronary artery delineation before any RVOT intervention to avoid interrupting an anomalous vessel 1

Long-Term Surveillance Protocol

Mandatory Annual Monitoring

Every patient requires annual evaluation including: 1

• History and physical examination by ACHD cardiologist 1
• 12-lead ECG with attention to QRS duration (>180 ms indicates high risk for ventricular tachycardia and sudden death) 4
• Comprehensive echocardiography assessing RV size/function, pulmonary regurgitation severity, residual RVOT obstruction, tricuspid regurgitation, and aortic root dimensions 1, 4
• Cardiac MRI for precise RV volume quantification and pulmonary regurgitation assessment 1, 4
• Periodic exercise testing to evaluate functional capacity and detect exertional arrhythmias 1, 4

Arrhythmia Surveillance

Periodic Holter monitoring should be performed, with frequency individualized based on hemodynamics and clinical suspicion. 1

• Annual surveillance with ECG and assessment of RV function is mandatory for all patients 1
• Electrophysiology testing in an ACHD center may be reasonable to define suspected arrhythmias 1
• The incidence of sudden death is approximately 2.5% per decade, primarily from ventricular tachycardia 1

Key Postoperative Complications to Monitor

Most Common: Pulmonary Regurgitation

Pulmonary regurgitation is the most frequently encountered problem in adults after TOF repair and is often missed on clinical examination because the murmur is short and quiet. 1, 4

This leads to progressive RV dilation and dysfunction, often with associated tricuspid regurgitation 1

Other Critical Residual Lesions

Monitor systematically for 1:

• Residual RVOT obstruction (valvular or subvalvular) with RV/LV pressure ratio >0.7 1, 4
• Branch pulmonary artery stenosis or hypoplasia 1
• Progressive aortic regurgitation often with aortic root dilatation 1
• Sustained ventricular tachycardia and sudden cardiac death risk 1
• AV block, atrial flutter, and atrial fibrillation 1

Indications for Reintervention

Class I Surgical Indications

Reoperation is indicated for: 1

• Symptomatic patients with severe pulmonary regurgitation 1
• Asymptomatic patients with severe pulmonary stenosis or pulmonary regurgitation PLUS progressive or severe RV enlargement or dysfunction 1
• Residual RVOT obstruction with RV/LV pressure ratio >0.7 1
• Residual VSD with left-to-right shunt >1.5:1 1
• Severe aortic regurgitation with symptoms or more than mild LV dysfunction 1
• Combination of multiple residual lesions causing RV enlargement or reduced function 1

Surgical Options for Rerepair

Pulmonary valve replacement is the most common reintervention 1:

• Heterograft (porcine or pericardial) or homograft preferred 1
• Mechanical PVR only for patients requiring warfarin for other indications (risk of late pannus formation) 1
• Patch augmentation of pulmonary annulus for proper prosthetic valve sizing 1

Additional procedures as needed 1:

• Resection of subvalvular obstruction and/or patch augmentation of RVOT, main or branch pulmonary arteries 1
• Residual/recurrent VSD closure via direct suture or patch revision 1
• AVR (tissue or mechanical) for significant aortic regurgitation 1
• Tricuspid valve repair or replacement for significant regurgitation 1

Arrhythmia Management Algorithm

Evaluation of Worrisome Symptoms

Any patient presenting with palpitations, dizziness, or syncope requires immediate comprehensive evaluation: 1

• Hemodynamic catheterization to identify repairable lesions 1
• Electrophysiology study for risk stratification and potential catheter ablation 1
• Echocardiography to assess for residual VSD or valve regurgitation 1

Treatment Strategy

For documented sustained ventricular tachycardia or cardiac arrest, implantable cardioverter defibrillator placement is mandatory. 1

• Preoperative EP testing and catheter ablation in the catheterization laboratory 1
• If unsuccessful, intraoperative mapping and ablation (VT focus typically in RVOT between VSD patch and pulmonary annulus) 1
• Postoperative ICD placement for patients at high risk of sudden death 1
• Maze procedure or modifications for atrial arrhythmias 1

Critical consideration: Even when ablation is acutely successful, recurrence risk remains too high not to place an ICD in patients with life-threatening arrhythmias 1

Genetic Screening

Screening for 22q11 deletion should be offered to all patients with TOF before pregnancy for appropriate genetic counseling. 1

• In absence of 22q11 deletion, offspring CHD risk is approximately 4-6% 1
• Fetal echocardiography should be offered in second trimester 1

Catheterization Indications

Catheterization should be performed in regional ACHD centers and is indicated for: 1

• Coronary artery delineation before any RVOT intervention (Class I) 1
• Better definition of potentially treatable causes of unexplained LV or RV dysfunction, fluid retention, chest pain, or cyanosis 1
• Branch pulmonary artery angioplasty when RV pressure >50% systemic or at lower pressures with RV dysfunction 1

Perioperative Management for Non-Cardiac Surgery

Preoperative Assessment Essentials

Obtain comprehensive echocardiography assessing RV size/function, pulmonary regurgitation severity, residual RVOT obstruction, tricuspid regurgitation, and aortic root dilation. 4

• Review recent cardiac MRI for RV volume and systolic function 4
• Analyze ECG for QRS duration >180 ms (high arrhythmia risk requiring enhanced monitoring) 4
• Assess exercise tolerance objectively through formal testing 4

Intraoperative Goals

Maintain RV function by optimizing preload, reducing afterload, and supporting contractility. 4

• Minimize increases in pulmonary vascular resistance by avoiding hypoxia, hypercarbia, acidosis, hypothermia, and excessive positive pressure ventilation 4
• Prevent tachycardia which reduces diastolic filling time and coronary perfusion 4
• Maintain systemic vascular resistance to prevent right-to-left shunting if residual ASD/VSD present 4
• Have defibrillator immediately available with antiarrhythmic medications prepared 4

Critical Pitfalls to Avoid

• Never underestimate RV dysfunction even in asymptomatic patients—decompensation can occur under anesthesia 4
• Avoid excessive positive pressure ventilation which increases RV afterload and impairs venous return 4
• Do not ignore QRS duration >180 ms as this significantly increases arrhythmia risk 4
• Ensure adequate pain control to prevent tachycardia and increased oxygen consumption 4