What is the approach to managing pulmonary arterial hypertension (PAH) in patients with atrial septal defect (ASD)?

Management of Pulmonary Arterial Hypertension in Atrial Septal Defect

Patients with atrial septal defect (ASD) and severe irreversible pulmonary arterial hypertension (PAH) should not undergo ASD closure, while those with reversible PAH should receive targeted PAH therapy followed by defect closure once pulmonary pressures improve. 1

Understanding PAH in ASD

PAH develops in ASD patients due to chronic left-to-right shunting, which causes:

• Increased pulmonary blood flow
• Progressive pulmonary vascular remodeling
• Eventual elevation of pulmonary vascular resistance (PVR)
• Right ventricular volume and pressure overload

Without intervention, up to 5-10% of ASD patients (predominantly female) may develop pulmonary vascular disease 1.

Assessment and Risk Stratification

Diagnostic Evaluation

• Echocardiography to assess:
  • RV size and function
  • Pulmonary artery pressure
  • Direction and magnitude of shunt
• Right heart catheterization to measure:
  • Pulmonary artery pressure
  • PVR
  • Pulmonary-to-systemic vascular resistance ratio
  • Response to vasodilator testing

Decision-Making Parameters

1. Favorable for ASD closure:

   • Pulmonary artery pressure less than two-thirds systemic levels
   • PVR less than two-thirds systemic vascular resistance
   • Evidence of significant left-to-right shunt (Qp:Qs ≥1.5:1)

2. Contraindication to ASD closure:

   • Severe irreversible PAH
   • No evidence of left-to-right shunt (Eisenmenger physiology)

Management Algorithm

1. For ASD with Mild-to-Moderate PAH

• Direct ASD closure (percutaneous or surgical) is indicated when:
  • Right atrial and RV enlargement are present
  • Pulmonary pressures are less than two-thirds systemic 1

2. For ASD with Severe PAH (but potentially reversible)

• "Treat-and-repair" strategy:

  1. Initial PAH-specific therapy:

     • For high-risk patients: IV epoprostenol as first-line therapy 2, 3
     • For intermediate risk: Oral combination therapy with endothelin receptor antagonist plus PDE-5 inhibitor (e.g., sildenafil) 2, 4

  2. Reassessment of hemodynamics after 3-6 months of PAH therapy

  3. ASD closure when:

     • PVR decreases by >20% 1
     • Mean PAP decreases significantly
     • Qp:Qs increases (indicating improved left-to-right shunt) 5

3. For ASD with Severe Irreversible PAH

• ASD closure is contraindicated 1
• Continue PAH-specific therapy:
  • Oral combination therapy with endothelin receptor antagonists and PDE-5 inhibitors
  • Prostacyclin analogues for severe cases
  • Consider lung transplantation for end-stage disease 1

Evidence for the "Treat-and-Repair" Strategy

Recent studies demonstrate that PAH-specific medications followed by ASD closure can be effective:

• In a study of 42 patients with ASD and severe PAH, targeted therapy reduced mean PAP from 45±15 to 35±9 mmHg and PVR from 6.9±3.2 to 4.0±1.5 Wood units, enabling successful transcatheter closure with good outcomes 5

• Case reports show that sildenafil therapy can improve oxygenation, exercise capacity, and pulmonary hemodynamics in patients with ASD and severe PAH 6

Practical Management Considerations

Perioperative Management

• Optimize PAH therapy before any procedure
• Avoid abrupt withdrawal of PAH medications
• Maintain adequate oxygenation (oxygen saturation >91%) 1
• Consider multidisciplinary approach with pulmonary hypertension specialists for perioperative management 1

Long-term Follow-up

• Annual clinical follow-up for patients with:

  • Persistent PAH after ASD repair
  • Atrial arrhythmias
  • RV or LV dysfunction 1

• Continue PAH-specific therapy after ASD closure until hemodynamics normalize

Common Pitfalls to Avoid

1. Closing ASD in patients with irreversible PAH - can lead to right heart failure and increased mortality

2. Failing to close ASD in patients with reversible PAH - missing the opportunity to prevent disease progression

3. Inadequate assessment of PAH severity - comprehensive hemodynamic evaluation is essential

4. Not considering "treat-and-repair" strategy - PAH-specific therapy can make previously inoperable patients candidates for closure 7, 5

5. Inappropriate use of calcium channel blockers - should only be used in vasoreactive patients 2

The management of PAH in ASD requires careful assessment of hemodynamics and pulmonary vascular reactivity, with decisions regarding closure based on objective parameters. The emerging "treat-and-repair" strategy offers hope for patients previously considered inoperable, but requires expertise in both PAH management and congenital heart disease.