Managing Arrhythmias in Adults With Congenital Heart Disease
Adults with congenital heart disease (ACHD) increasingly survive into later decades, but repaired anatomy rarely becomes electrically normal. Surgical scars, prosthetic material, chamber enlargement, abnormal pressure loading, hypoxemia, and progressive ventricular dysfunction can create a substrate for atrial and ventricular arrhythmias. The clinical task is therefore broader than terminating an episode: it involves identifying the underlying anatomy, assessing hemodynamic consequences, reducing sudden-death risk, and preserving long-term cardiac function.
A practical strategy combines congenital cardiology, clinical electrophysiology, advanced imaging, and device expertise. Arrhythmia presentations may be subtle, including reduced exercise capacity, palpitations, syncope, chest discomfort, or unexplained cyanosis. In some patients, an apparently routine atrial tachycardia is the first sign of failing surgical repair or rising filling pressures.
The Journal of Arrhythmia provides a useful setting for current evidence, educational resources, and specialist perspectives; its journal resources support clinicians and trainees working across electrophysiology and congenital heart disease.
Define The Substrate Before Treating The Rhythm
The first assessment should establish the congenital diagnosis, operative history, current anatomy, and prior rhythm procedures. Important details include the type and timing of repair, systemic and subpulmonary ventricles, conduit or valve prostheses, baffle pathways, residual shunts, coronary anatomy, and previous sternotomies. Operative reports and imaging from childhood may be more informative than a broad diagnostic label such as “repaired tetralogy of Fallot.”
A 12-lead electrocardiogram should be compared with earlier tracings, looking for QRS duration, bundle-branch block, atrioventricular conduction disease, atrial enlargement, ventricular hypertrophy, and repolarization abnormalities. Ambulatory monitoring helps quantify premature beats, atrial tachycardia, atrial fibrillation, nonsustained ventricular tachycardia, pauses, and chronotropic response. Exercise testing can reveal exertional arrhythmia, impaired cardiac output, or a mismatch between symptoms and resting findings.
Echocardiography is usually the starting point for structural assessment, but cardiac magnetic resonance is often essential when right ventricular volume, scar, conduit function, or biventricular performance is uncertain. Computed tomography may be valuable for complex vascular pathways, venous access, calcified conduits, and procedural planning. The rhythm diagnosis should be interpreted alongside these findings rather than treated as an isolated electrical problem.
Recognize Common Arrhythmia Patterns
Atrial arrhythmias are frequent in ACHD and include intra-atrial reentrant tachycardia, scar-related macroreentrant atrial tachycardia, focal atrial tachycardia, atrial flutter, and atrial fibrillation. Risk rises with atrial dilation, valve disease, elevated filling pressures, pulmonary hypertension, and prior atriotomy. Fontan circulation, atrial switch repairs, and extensive atrial surgery create particularly complex circuits.
Symptoms may be poorly tolerated because a rapid atrial rhythm can sharply reduce ventricular filling in a stiff or hypertrophied ventricle. In Fontan physiology, loss of atrioventricular synchrony and increased venous pressure can produce an abrupt decline in exercise capacity or protein-losing enteropathy. Atrial arrhythmia should prompt evaluation for ventricular dysfunction, valve obstruction or regurgitation, baffle problems, thrombus, and worsening cyanosis.
Ventricular ectopy and ventricular tachycardia are especially important in repaired tetralogy of Fallot, systemic right ventricular conditions, left-sided obstructive lesions, and patients with significant ventricular scar. Risk markers include ventricular dysfunction, extensive late gadolinium enhancement, prolonged QRS duration, syncope, frequent ventricular ectopy, inducible sustained ventricular tachycardia, and prior cardiac arrest. No single marker provides a complete risk estimate, so decisions should integrate the whole clinical picture.
Stabilize The Patient And Correct Triggers
Acute management begins with hemodynamic status. Synchronized cardioversion is appropriate for an unstable tachyarrhythmia, while stable patients require rhythm identification, electrolyte correction, treatment of fever or infection, and review of medications. Hypokalemia, hypomagnesemia, thyroid disease, anemia, sleep-disordered breathing, stimulant exposure, alcohol, and decompensated heart failure can initiate or sustain arrhythmia.
Drug selection requires attention to anatomy and ventricular function. Class Ic agents are generally unsuitable in significant structural heart disease, while sotalol and other QT-prolonging drugs require renal and electrocardiographic monitoring. Amiodarone may suppress atrial or ventricular arrhythmias but carries important thyroid, hepatic, pulmonary, ocular, and drug-interaction risks. In patients with a systemic right ventricle, Fontan circulation, or advanced heart failure, even modest negative inotropy can be clinically consequential.
Anticoagulation should be individualized. Conventional atrial fibrillation risk scores may underestimate thromboembolic risk in certain congenital lesions, particularly with Fontan physiology, residual shunts, atrial dilation, prosthetic material, or prior thromboembolism. The decision should consider the arrhythmia burden, anatomy, bleeding risk, liver function, cyanosis, pregnancy potential, and planned interventions. Cardioversion requires appropriate imaging and anticoagulation precautions when arrhythmia duration or thrombus status is uncertain.
Choose Ablation With Anatomical Precision
Catheter ablation can provide durable control for many macroreentrant atrial tachycardias, but procedural success depends on understanding the circuit and the access route. Atrial tachycardia after atriotomy often involves channels between scar and anatomic barriers. Intra-atrial reentry may require entrainment, high-density mapping, and confirmation of bidirectional block across the critical isthmus. Ablation should address the mechanism rather than relying on empiric linear lesions alone.
The approach may be complicated by baffles, interrupted venous pathways, surgically created conduits, mechanical valves, or limited femoral access. Transseptal puncture, retrograde access, transbaffle puncture, or hybrid approaches may be considered according to the anatomy and operator experience. Preprocedural imaging, three-dimensional electroanatomic mapping, and careful anticoagulation management can reduce avoidable risk.
For highly altered anatomy, three-dimensional planning illustrates how patient-specific models may help teams understand chambers, scars, conduits, and access routes before a complex ablation. Such tools complement, rather than replace, intracardiac mapping and real-time imaging.
| Clinical setting | Key concerns | Practical management focus |
|---|---|---|
| Repaired tetralogy of Fallot | RV dilation, pulmonary regurgitation, scar-related VT, atrial tachycardia | CMR, pulmonary valve assessment, VT risk stratification, targeted ablation |
| Fontan circulation | Atrial reentry, thromboembolism, low output, protein-losing enteropathy | Urgent rhythm control, anticoagulation assessment, specialist ablation planning |
| Atrial switch repair | Systemic RV dysfunction, baffle obstruction, sinus-node disease | Baffle imaging, rhythm monitoring, systemic RV optimization, device planning |
| Congenitally corrected transposition | Systemic RV failure, progressive AV block, atrial arrhythmias | Conduction surveillance, heart-failure care, pacing strategy |
| Prosthetic valve or conduit | Access limitations, infection risk, obstruction, ventricular loading | Multimodality imaging and coordinated electrophysiology–structural review |
Plan Pacing And Defibrillator Therapy Carefully
Bradyarrhythmia may result from sinus-node dysfunction, atrioventricular block, surgical injury, aging conduction tissue, or antiarrhythmic medication. Symptoms, ventricular function, escape rhythm, and the likelihood of progression should guide pacing decisions. In patients with complex venous anatomy, standard transvenous implantation may be difficult or impossible, and chronic leads can complicate future surgery, venous drainage, or valve interventions.
Device selection should account for the systemic ventricle, anticipated pacing burden, ventricular synchrony, shunts, cyanosis, infection history, and future access. Conduction-system pacing or cardiac resynchronization may be considered when conventional right ventricular pacing could worsen dyssynchrony, although evidence in ACHD remains more limited than in acquired heart disease. Epicardial systems, leadless pacemakers, subcutaneous defibrillators, and hybrid strategies may have roles in selected patients.
Lead extraction is particularly complex when abandoned or fractured leads coexist with congenital venous pathways, baffles, intracardiac shunts, or prior surgical material. A dedicated review of lead management emphasizes why extraction decisions should be individualized, balancing infection, vascular access, embolic risk, procedural injury, and the need for future device therapy.
Primary-prevention implantable cardioverter-defibrillator decisions require shared evaluation of ventricular function, scar, syncope, ventricular tachycardia, hemodynamics, and lesion-specific risk. Standard ejection-fraction thresholds may not capture the risk in ACHD. Conversely, device implantation carries substantial long-term burdens, including inappropriate shocks, lead failure, infection, venous obstruction, and repeated procedures over a young patient’s lifetime.
Build Long-Term Rhythm Surveillance
Follow-up should be organized around the patient’s lesion, repair, ventricular function, and previous arrhythmia rather than a fixed annual template. Monitoring frequency increases after cardioversion, ablation, device implantation, hospitalization, or a change in ventricular performance. Remote device monitoring, wearable sensors, and intermittent ambulatory ECG can detect asymptomatic recurrence, but symptoms and exercise tolerance remain essential clinical measures.
Lifestyle and comorbidity management support rhythm control. Patients should receive individualized advice about exercise, sleep, alcohol, stimulant medications, pregnancy, contraception, and dental or surgical procedures. Exercise is usually beneficial when tailored to anatomy and hemodynamics; blanket restriction can worsen conditioning and quality of life. Pregnancy planning requires preconception assessment of ventricular function, pulmonary pressures, anticoagulation, medication safety, and arrhythmia history.
Every care plan should identify warning signs that require urgent review, including syncope, sustained palpitations, new cyanosis, rapid weight gain, worsening edema, chest pain, severe breathlessness, or repeated device therapies. Coordination between an ACHD cardiologist, electrophysiologist, imaging specialist, heart-failure team, and, when needed, congenital cardiac surgeon is especially important for patients with Fontan physiology, systemic right ventricles, or complex device anatomy.
Practical Priorities For Clinical Care
- Confirm the congenital anatomy and operative history before selecting antiarrhythmic, ablation, or device therapy.
- Use cardiac magnetic resonance, computed tomography, and three-dimensional mapping when echocardiography cannot define the substrate or access route.
- Treat atrial arrhythmia as a possible marker of hemodynamic deterioration, valve disease, baffle dysfunction, or ventricular failure.
- Reassess thromboembolic risk individually, including cyanosis, Fontan physiology, prosthetic material, and prior thrombosis.
- Refer complex ablation, lead extraction, and defibrillator decisions to teams experienced in adult congenital electrophysiology.
Effective arrhythmia care in ACHD is a continuing process of anatomical reassessment, rhythm surveillance, and coordinated intervention. Clinicians can use the Journal of Arrhythmia’s peer-reviewed research, guidelines, and educational collections to refine decisions as evidence evolves. Explore the journal’s specialist content and apply a structured, lesion-specific approach in practice to improve rhythm control, procedural safety, and lifelong cardiac care.