Do you give beta (beta blockers) to patients with Fontan circulation who develop tachycardia?

Management of Tachycardia in Fontan Circulation Patients

Beta blockers can be used cautiously in Fontan patients who develop tachycardia, but careful monitoring is essential due to potential risks of decreased cardiac output and ventricular dysfunction.

Understanding Fontan Circulation and Tachycardia

Patients with Fontan circulation have a unique cardiovascular physiology where systemic venous return flows passively to the pulmonary arteries without a subpulmonary ventricle. This makes them particularly vulnerable to rhythm disturbances:

• Atrial arrhythmias occur in up to 35% of Fontan patients during follow-up 1
• Tachycardia can significantly compromise cardiac output in this population
• Intra-atrial reentrant tachycardia (IART) is a common arrhythmia in these patients

Treatment Approach for Tachycardia in Fontan Patients

First-Line Management

1. Identify and treat underlying causes:

   • Evaluate for Fontan pathway obstruction (hepatic distension and jugular venous distension may indicate this) 2
   • Check for electrolyte abnormalities
   • Rule out infection or other systemic illness

2. Anticoagulation:

   • Warfarin should be initiated for patients with atrial arrhythmias to prevent thromboembolism (Class I recommendation) 2

Pharmacological Management

For acute tachycardia management:

• Beta blockers can be used with caution in hemodynamically stable patients 2
• Calcium channel blockers (diltiazem, verapamil) may be considered as alternatives in stable patients without ventricular dysfunction 2
• Avoid medications that may depress sinus node function or AV conduction, as venous access for pacing may be limited due to complex anatomy 2

For chronic management:

• ACE inhibitors and diuretics are reasonable for single ventricle dysfunction (Class IIa recommendation) 2
• Antiarrhythmic drugs should be selected carefully due to potential negative inotropic effects

Important Considerations and Risks

• Cardiac output dependence: Fontan circulation is preload-dependent and relies heavily on heart rate for adequate cardiac output
• Ventricular function: Beta blockers may further compromise already reduced cardiac output
• Monitoring requirements:
  • Regular assessment of ventricular function
  • Evaluation for signs of decreased cardiac output (fatigue, hypotension)
  • Close follow-up with a specialist in adult congenital heart disease

Evidence for Beta Blocker Use in Fontan Patients

Research on beta blocker use in Fontan patients shows mixed results:

• A 2023 study found that lower heart rates with beta blockers could potentially improve diastolic function in some Fontan patients by optimizing the E-wave and A-wave relationship 3
• However, a 2021 randomized crossover trial showed that carvedilol did not improve exercise performance in Fontan patients and was associated with increased NT-proBNP levels 4

Expert Recommendations

The ACC/AHA guidelines for adults with congenital heart disease recommend:

1. Management of patients with Fontan circulation should be coordinated with a regional Adult Congenital Heart Disease center (Class I recommendation) 2
2. Arrhythmia management requires consultation with an electrophysiologist (Class I recommendation) 2
3. New-onset atrial tachyarrhythmias should prompt comprehensive imaging to identify potential Fontan pathway abnormalities or ventricular dysfunction (Class I recommendation) 2

Conclusion

When managing tachycardia in Fontan patients, beta blockers can be used with careful monitoring, but treatment must be individualized based on the specific arrhythmia, hemodynamic stability, and ventricular function. Consultation with specialists in adult congenital heart disease and cardiac electrophysiology is essential for optimal management.