Management of Tetralogy of Fallot
Surgical Repair Strategy
All patients with Tetralogy of Fallot require complete surgical repair, ideally performed within the first year of life, addressing all four anatomic components: VSD closure, RVOT obstruction relief, pulmonary valve management, and extracardiac conduit placement when necessary. 1
Timing and Approach
- Symptomatic neonates (hypercyanotic spells, ductal-dependent circulation) weighing <4 kg should undergo palliative modified Blalock-Taussig shunt followed by complete repair at 6-12 months 2
- Asymptomatic patients weighing <4 kg with threatened pulmonary artery isolation require BT shunt and repair at 6-12 months 2
- All other patients should undergo complete repair after 6 months of age, with current practice favoring repair before 6 months with mortality <2% 3, 4
- Complete repair includes VSD closure and relief of RVOT obstruction through infundibular muscle resection, pulmonary valvotomy, and transannular patch when the pulmonary annulus is inadequate 5
Lifelong Surveillance Requirements
Every patient with repaired TOF requires mandatory annual follow-up with an adult congenital heart disease (ACHD) specialist for life, as pulmonary regurgitation, RV dysfunction, and arrhythmias determine long-term morbidity and mortality. 1
Annual Evaluation Components
- Clinical assessment by ACHD cardiologist with focused history on exercise tolerance, palpitations, dizziness, or syncope 5, 1
- 12-lead ECG to monitor QRS duration—QRS ≥180 ms identifies high risk for sustained ventricular tachycardia and sudden cardiac death 5, 6
- Comprehensive transthoracic echocardiography assessing RV size/function, pulmonary regurgitation severity, residual RVOT obstruction, tricuspid regurgitation, and aortic root dilation 1, 6
- Cardiac MRI for precise RV volume quantification and pulmonary regurgitation assessment, as echocardiography underestimates RV dysfunction 5, 1, 6
- Periodic Holter monitoring with frequency individualized based on hemodynamics and clinical suspicion to detect ventricular arrhythmias 5, 1
- Exercise testing to objectively assess functional capacity and detect exertional arrhythmias 5, 6
Arrhythmia Management and Sudden Death Prevention
The incidence of sudden death in adult TOF patients is approximately 2.5% per decade, with ventricular tachycardia as the primary mechanism. 5
Risk Stratification and Intervention
- Worrisome symptoms (palpitations, dizziness, syncope) mandate immediate evaluation with hemodynamic catheterization and electrophysiology study 5
- Documented sustained ventricular tachycardia or cardiac arrest requires implantable cardioverter defibrillator (ICD) placement—this is now standard at all centers with little debate 5
- Asymptomatic patients with nonsustained VT on surveillance monitoring should undergo electrophysiology study to refine arrhythmia risk, with consideration for surgery if significant pulmonary regurgitation exists 5
- Inducible VT/VF or spontaneous sustained VT warrants ICD implantation if meaningful survival >1 year is expected 5
- Recurrent sustained monomorphic VT or recurrent ICD shocks can be effectively treated with catheter ablation, though ICD remains necessary due to uncertain recurrence risk after ablation 5
- Beta blockers should be used in patients with frequent or complex ventricular arrhythmias to reduce sudden cardiac arrest risk 5
Critical Warning
Prophylactic antiarrhythmic therapy with class Ic medications (flecainide, propafenone) or amiodarone in asymptomatic patients with VA is potentially harmful and should not be used. 5
Reintervention Criteria
Pulmonary valve replacement (PVR) is the most common reintervention, required in 40-85% of patients 5-10 years after initial repair due to chronic pulmonary regurgitation causing progressive RV dilation and dysfunction. 5
Indications for Reoperation
- Symptomatic patients with severe pulmonary regurgitation require intervention 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 or RV systolic pressure >50 mmHg 1, 6
- Hemodynamic abnormalities identified during evaluation for arrhythmias, such as residual VSD or significant valve regurgitation, may benefit from surgical intervention combined with intraoperative VT mapping and ablation 5
Valve Selection
- Heterograft or homograft preferred for pulmonary valve replacement 1
- Mechanical PVR only for patients requiring warfarin for other indications 1
- Percutaneous approaches should be performed before irreversible RV remodeling but ideally after growth completion to minimize repeated interventions 5
Perioperative Management for Non-Cardiac Surgery
Preoperative Assessment
- Comprehensive echocardiography must assess RV size/function, pulmonary regurgitation severity, residual RVOT obstruction, tricuspid regurgitation, and aortic root dilation 6
- Review cardiac MRI for RV volume, systolic function, and pulmonary regurgitation severity 6
- Analyze ECG for QRS duration >180 ms, which mandates enhanced monitoring due to significantly increased arrhythmia risk 6
- Coronary anatomy must be defined before any RVOT intervention to avoid interrupting important coronary vessels 5
Intraoperative Goals
- Maintain RV function by optimizing preload, reducing afterload, and supporting contractility 1, 6
- Minimize increases in pulmonary vascular resistance by avoiding hypoxia, hypercarbia, acidosis, hypothermia, and excessive positive pressure ventilation 6
- Prevent tachycardia which reduces diastolic filling time and coronary perfusion 6
- Maintain systemic vascular resistance to prevent right-to-left shunting if residual ASD/VSD present 6
- Defibrillator must be immediately available with antiarrhythmic medications prepared 1, 6
Critical Pitfalls to Avoid
- Underestimating RV dysfunction even in asymptomatic patients can lead to decompensation under anesthesia 6
- Inadequate preoperative assessment without recent echocardiography and knowledge of residual lesions significantly increases risk 6
- Excessive positive pressure ventilation increases RV afterload and impairs venous return 6
- Ignoring QRS duration >180 ms substantially increases arrhythmia risk and should prompt enhanced monitoring 6
- Delaying PVR until irreversible RV remodeling occurs worsens outcomes—intervention should occur before this threshold 5
Pregnancy Considerations
- Pregnancy is contraindicated in patients with unrepaired TOF 5
- After repair, pregnancy is usually well tolerated if no important hemodynamic residua exist, functional capacity is good, and RV function is no more than mildly depressed with maintained sinus rhythm 5
- Fetal risk: 4-6% risk of congenital heart disease in offspring; screening for 22q11.2 microdeletion should be performed before pregnancy for appropriate genetic counseling 5, 4
- Fetal echocardiography should be offered in the second trimester 5