What are the benefits of closing a fenestration in a Fontan circulation?

Benefits of Closing Fontan Fenestration

Closing a Fontan fenestration significantly improves systemic oxygen saturation (by approximately 8-9%), reduces the risk of paradoxical thromboembolism, and allows for complete separation of systemic and pulmonary circulations—the ultimate physiologic goal in single-ventricle patients. 1, 2

Primary Benefits

Improved Oxygenation

• Resting oxygen saturation increases from approximately 85-87% to 94-95% following fenestration closure, representing a mean improvement of 7.9-9.4% 3, 4, 5
• Exercise oxygen saturation improves dramatically, rising from approximately 66% to 87% during physical activity 6
• These improvements in oxygenation are sustained long-term, with saturation remaining elevated at 94.5% even after 7+ years of follow-up 3

Reduced Thromboembolic Risk

• Patent fenestrations create an obligatory right-to-left shunt in the setting of cyanosis and low-flow venous circulation, substantially increasing the risk of paradoxical thromboembolism 1, 2
• Closure eliminates this pathway for systemic embolization, addressing a critical long-term safety concern 2

Physiologic Completion of Fontan Circulation

• The ultimate goal in single-ventricle patients is complete partitioning of systemic and pulmonary circulations 1
• Fenestration closure achieves this goal when hemodynamics permit, restoring more normal circulatory physiology 2

Secondary Clinical Benefits

Symptomatic Improvement

• Clinical symptomatology improves and remains sustained in long-term follow-up after closure 1
• Reduced need for anticongestive medications: patients require less digoxin and diuretics following closure 5
• Improved somatic growth: both height and weight percentiles increase significantly after fenestration closure 5

Exercise Capacity

• Exercise duration increases modestly by approximately 1.7-2 minutes, though this may be clinically marginal 4, 6
• The evidence on objective exercise testing improvements is mixed and inconsistent across studies 1

Hemodynamic Trade-offs

Acceptable Pressure Changes

• Fontan pressure increases modestly by approximately 1.4 mmHg following closure 4
• This small pressure elevation is generally well-tolerated when patients meet appropriate closure criteria 2, 7
• Cardiac index decreases from approximately 4.0 to 2.9 L/min/m² immediately after closure, but this is acceptable when test occlusion is tolerated 3

Safety Profile

Low Complication Rates

• Procedural success rates are high with transcatheter closure techniques 1
• Major complications occur in only 4% of patients, with minor complications in 6.3% 4
• Long-term adverse outcomes are rare: death (1.3-2%), transplant (2%), and protein-losing enteropathy (2%) over 7-10 years of follow-up 3, 5

Critical Decision-Making Algorithm

Test Occlusion Protocol

• Perform complete hemodynamic catheterization with temporary balloon occlusion for 10-20 minutes 1, 2
• Acceptable hemodynamic criteria for closure include:
  • Improved systemic oxygen saturation
  • Only modest rise in Fontan pressure
  • Minimal fall in cardiac output 1, 2

Contraindications to Closure

• High baseline left atrial pressure predicts poor outcomes with closure 7
• Significant increase in Fontan pressure during balloon occlusion testing (odds ratio 2.2 for non-closure) 7
• Moderate-to-severe atrioventricular valve regurgitation is associated with non-closure decisions 7
• NYHA Class III symptoms at baseline suggest closure may not be tolerated 7

Guideline Recommendation

The American Heart Association provides a Class IIa recommendation (Level C evidence) that transcatheter closure of a chronic Fontan fenestration is reasonable when the patient demonstrates favorable hemodynamics and tolerates test occlusion 1, 2

Common Pitfalls to Avoid

• Never close without adequate hemodynamic assessment: thorough testing with temporary occlusion is essential to prevent Fontan failure 2, 7
• Do not leave fenestrations permanently patent without justification: this increases thromboembolic risk without proven long-term benefit 2
• Avoid closure in patients with elevated left atrial pressure or significant pressure rise during test occlusion: these patients are at high risk for adverse outcomes 7
• Recognize that no patient in major series required fenestration re-creation after closure, supporting the safety of closure when appropriate criteria are met 3