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

Management of Tetralogy of Fallot

Definitive Surgical Repair

All patients with TOF require complete surgical repair addressing all four anatomic components: VSD closure, RVOT obstruction relief, pulmonary valve management, and extracardiac conduit placement when necessary, ideally within the first year of life. 1, 2

• Surgeons with specialized training and expertise in congenital heart disease must perform all operations in TOF patients, as this directly impacts morbidity and mortality outcomes. 3
• The surgical approach typically involves infundibulotomy, resection of obstructive muscle bundles, and patch enlargement of the pathway from right ventricle to pulmonary arteries. 3
• Coronary artery anatomy must be definitively established before any operative intervention, specifically identifying anomalous anterior descending coronary arteries crossing the RVOT to prevent catastrophic coronary injury. 3

Lifelong Surveillance Requirements

Every patient requires annual evaluation by an adult congenital heart disease (ACHD) specialist for life, as 35-year survival is approximately 85% but residual lesions are nearly universal. 3, 1

Mandatory Annual Testing:

• Comprehensive echocardiography assessing RV size/function, pulmonary regurgitation severity, residual RVOT obstruction, tricuspid regurgitation, and aortic root dilation. 3, 1
• 12-lead ECG with specific attention to QRS duration >180 ms, which indicates significantly increased risk of ventricular tachycardia and sudden cardiac death. 4, 1
• Cardiac MRI for precise RV volume quantification and pulmonary regurgitation assessment, as this is the reference standard and echocardiography commonly underestimates these parameters. 3, 5
• Periodic Holter monitoring with frequency based on hemodynamics and clinical suspicion to detect exertional arrhythmias. 1

Indications for Pulmonary Valve Replacement

Class I (Must Perform):

Pulmonary valve replacement (surgical or percutaneous) is mandatory for symptomatic patients with moderate or greater pulmonary regurgitation and cardiovascular symptoms not otherwise explained. 3

Class IIa (Should Strongly Consider):

Pulmonary valve replacement is strongly indicated in asymptomatic patients with moderate or greater pulmonary regurgitation plus any of the following: 3

• Moderate to severe RV dysfunction 3
• Moderate to severe RV enlargement 3
• Development of symptomatic or sustained atrial and/or ventricular arrhythmias 3
• Moderate to severe tricuspid regurgitation 3

Additional Surgical Indications:

Surgery is strongly indicated for residual RVOT obstruction when: 3

• Peak instantaneous echocardiography gradient >50 mm Hg 3
• RV/LV pressure ratio >0.7 3
• Progressive and/or severe RV dilatation with dysfunction 3

Residual VSD with left-to-right shunt >1.5:1 requires surgical closure. 3

Arrhythmia Management and Sudden Death Prevention

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

• Primary prevention ICD therapy is strongly indicated in adults with TOF and multiple risk factors for sudden cardiac death, including QRS duration >180 ms, severe RV dysfunction, or LV ejection fraction ≤35% with NYHA class II-III symptoms. 3
• Programmed ventricular stimulation can risk-stratify adults with TOF and additional risk factors for sudden cardiac death. 3
• Prevalence of atrial and ventricular arrhythmias is approximately 20% and 15% respectively, with steep increases after age 45. 3

Medical Management

Most patients require no regular medication in the absence of significant residual hemodynamic abnormality. 3

• Heart failure medications are necessary only in the setting of documented RV and LV dysfunction. 3

Diagnostic Catheterization Indications

Cardiac catheterization with angiography is indicated when adequate hemodynamic data cannot be obtained noninvasively, specifically for: 3

• Assessment in the setting of arrhythmia, heart failure, unexplained ventricular dysfunction 3
• Suspected pulmonary hypertension or cyanosis 3
• Coronary artery compression testing before RV-to-PA conduit stenting or transcatheter valve placement 3
• Simultaneous therapeutic interventions including pulmonary artery balloon dilatation, stent placement, and pulmonary valve replacement 3

Critical Pitfalls to Avoid

Never underestimate RV dysfunction even in asymptomatic patients, as decompensation can occur rapidly under physiologic stress. 4

• Inadequate preoperative assessment without recent echocardiography and knowledge of residual lesions significantly increases perioperative risk. 4
• Ignoring QRS duration >180 ms dramatically increases arrhythmia risk and mandates enhanced monitoring and consideration for ICD placement. 4
• The incidence of sudden cardiac death after surgical repair is approximately 2% per decade, making vigilant surveillance essential. 3