What is the role of atrial septostomy in treating severe pulmonary hypertension?

Role of Atrial Septostomy in Severe Pulmonary Hypertension

Atrial septostomy should be considered in select patients with severe pulmonary arterial hypertension who are unresponsive to maximal medical therapy, but should only be performed at institutions with significant procedural and clinical experience. 1

Mechanism and Rationale

Atrial septostomy is the iatrogenic creation of an atrial septal defect that:

• Decompresses the failing right ventricle
• Increases left ventricular preload
• Improves cardiac index and systemic blood flow
• Increases systemic oxygen transport despite arterial oxygen desaturation 1

The procedure is based on observations that PAH patients with Eisenmenger syndrome or a patent foramen ovale tend to have better long-term outcomes 1.

Patient Selection

Appropriate Candidates:

• Patients with severe PAH who are:
  • NYHA/WHO functional class III or IV 1
  • Experiencing recurrent syncope despite maximal medical therapy 1, 2
  • Suffering from refractory right heart failure 1, 2
  • Awaiting lung transplantation (as a bridge) 1, 2

Contraindications/High-Risk Features:

• Impending death or severe right ventricular failure on maximal cardiorespiratory support 2
• Mean right atrial pressure >20 mmHg 2, 3
• Pulmonary vascular resistance index >55 units/m² 2
• Baseline systemic oxygen saturation <90% on room air 2
• Predicted 1-year survival <40% 2
• Advanced age and poor renal function (creatinine clearance <50 ml/min) 4

Procedural Considerations

The procedure is typically performed by experienced interventional cardiologists using:

• Blade septostomy approach with a series of balloon dilatations 1
• Fluoroscopic guidance 4
• Careful monitoring of left atrial pressure, oxygen saturation, and mean right atrial pressure 2

Clinical Benefits

Successful atrial septostomy can provide:

• Improved cardiac index (15-58% increase) 1
• Decreased right atrial pressure 1
• Enhanced systemic oxygen transport 4
• Improved NYHA functional class and exercise tolerance 1, 4
• Potential improvement in survival compared to predicted natural history 3

In a recent study, patients showed 100% 1-year and 83.3% 3-year survival rates after the procedure 5.

Risks and Complications

The procedure carries significant risks:

• Overall procedure-related mortality: 13-16% 1, 2
• Potential complications include:
  • Cardiac tamponade
  • Arrhythmias
  • Refractory hypoxemia
  • Balloon rupture and embolization
  • Failure of balloon deflation
  • Cardiac perforation
  • Vascular injury
  • Embolic complications including stroke 1

Timing of Intervention

Early intervention is safer and potentially more effective than using atrial septostomy as a rescue therapy 1. The key to success is selecting patients with moderate to severe disease where the procedure can be performed electively rather than as an emergency measure 1.

Post-Procedure Management

After septostomy:

• Optimize oxygen delivery
• Consider transfusion of packed red blood cells or erythropoietin if needed to increase oxygen content 2
• Continue optimal PAH-specific medical therapy
• Monitor for potential closure of the septal defect, which may require repeat procedures 1

Role in Overall Treatment Strategy

Atrial septostomy should be considered:

1. As part of a comprehensive treatment plan for severe PAH
2. When medical therapy has failed to achieve adequate clinical response
3. As a bridge to lung transplantation 1, 6
4. As a palliative measure when no other options exist 2

The procedure should be viewed as palliative rather than curative, as it does not affect the underlying disease process 2.