What is the summary of Atrial Septal Defects (ASDs) from diagnosis to treatment?

Atrial Septal Defect (ASD): Comprehensive Management from Diagnosis to Treatment

Closure of an ASD is indicated for all patients with right atrial and right ventricular enlargement, with or without symptoms, provided pulmonary arterial pressure is less than two-thirds systemic pressure and pulmonary vascular resistance is less than two-thirds systemic resistance. 1, 2

Types of Atrial Septal Defects

ASDs are persistent communications between the atria and include several anatomical types:

1. Secundum ASD (most common, 80-90%)

   • Located in the region of the fossa ovalis
   • Only type amenable to percutaneous closure

2. Primum ASD

   • Located inferiorly near the crux of the heart
   • Part of partial atrioventricular septal defect
   • Requires surgical repair

3. Sinus Venosus ASD

   • Superior type: near superior vena caval entry
   • Inferior type: near inferior vena caval entry
   • Often associated with partial anomalous pulmonary venous return
   • Requires surgical repair

4. Coronary Sinus ASD

   • Uncommon defect causing shunting through the coronary sinus ostium
   • Requires surgical repair

Pathophysiology and Clinical Presentation

The primary hemodynamic consequence of an ASD is left-to-right shunting leading to:

• Right ventricular volume overload
• Pulmonary overcirculation
• Right atrial enlargement

Common symptoms include:

• Fatigue and exercise intolerance
• Palpitations (from atrial arrhythmias)
• Frequent pulmonary infections
• Paradoxical embolism (in right-to-left shunting)
• Orthodeoxia-platypnea (in some cases)

Many patients with small defects remain asymptomatic for decades, with symptoms developing in adulthood due to:

• Decreased left ventricular compliance (from hypertension, coronary disease)
• Development of atrial arrhythmias
• Progressive right ventricular dysfunction

Diagnostic Approach

Initial Evaluation

• Transthoracic echocardiography (TTE) is the first-line imaging modality 1, 2
  • Identifies defect location and size
  • Assesses right heart enlargement
  • Estimates pulmonary pressures
  • Quantifies shunt magnitude (Qp:Qs ratio)

Advanced Imaging

• Transesophageal echocardiography (TEE) is indicated when: 1, 2

  • TTE is inadequate
  • Superior sinus venosus defects are suspected
  • Anomalous pulmonary venous connections need evaluation
  • Detailed atrial septal anatomy is required for device closure planning

• Cardiac catheterization is recommended when: 1

  • Pulmonary hypertension is suspected
  • Coronary artery disease risk exists in older patients
  • Hemodynamic data is needed before closure in borderline cases

• Maximal exercise testing can be useful to: 1

  • Document exercise capacity in patients with discrepant symptoms
  • Detect changes in oxygen saturation with exercise
  • NOT recommended in severe pulmonary arterial hypertension

Indications for ASD Closure

Class I Indications (Strong) 1, 2

• Right atrial and RV enlargement with or without symptoms
• Paradoxical embolism
• Documented orthodeoxia-platypnea

Contraindications for Closure 2

• Severe irreversible pulmonary arterial hypertension with:
  • PA systolic pressure >2/3 systemic
  • Pulmonary vascular resistance >2/3 systemic
  • Net right-to-left shunt

Small ASDs

• Small defects (<5mm) without RV volume overload generally don't require closure
• Exception: paradoxical embolism history

Treatment Approaches

Percutaneous Closure

• Preferred for secundum ASDs with adequate rims for device anchoring 1, 2
• Advantages over surgery:
  • Shorter hospital stay
  • Avoidance of sternotomy
  • Lower cost
  • More rapid recovery
• Available devices include:
  • Amplatzer Septal Occluder (most commonly used)
  • Gore HELEX device (for small to medium defects)
  • Amplatzer Cribriform device (for fenestrated ASDs)

Surgical Closure

• Indicated for: 1, 2
  • Sinus venosus, coronary sinus, or primum ASDs
  • Secundum ASDs with inadequate rims for device placement
  • Large secundum ASDs (>38mm)
  • Need for concomitant cardiac surgery (e.g., tricuspid valve repair)
• Techniques include:
  • Pericardial patch closure
  • Direct suture closure
  • Warden procedure (for sinus venosus ASD with anomalous pulmonary venous drainage)

Post-Closure Management

Monitoring for Complications

• Device migration/erosion
• Residual shunting
• Thrombus formation
• Pericardial effusion
• Arrhythmias

Follow-up Schedule 2

• Echocardiographic evaluation at:
  • 24 hours post-closure
  • 1 month
  • 6 months
  • 1 year
  • Regular intervals thereafter

Medication

• Low-dose aspirin for at least 6 months after device closure 2
• Antiarrhythmic therapy if atrial arrhythmias develop
• Anticoagulation for atrial fibrillation 1

Special Considerations

Atrial Arrhythmias

• Common in adults with longstanding ASDs
• Treatment should aim to restore and maintain sinus rhythm 1
• Consider anticoagulation for atrial fibrillation
• Consider concomitant Maze procedure during surgical repair for chronic atrial fibrillation/flutter

Pulmonary Hypertension

• Accurate evaluation of pulmonary pressures is crucial before closure
• In select patients with pulmonary arterial hypertension unresponsive to medical management, atrial septostomy may be considered to preserve cardiac output 1

Long-term Outcomes

Closure of ASDs provides significant benefits:

• Improved functional capacity
• Reduced right ventricular dimensions and pressure
• Prevention of right heart failure
• Reduced risk of atrial arrhythmias
• Protective effect on mortality rate

Early closure (before age 25) yields better long-term outcomes than delayed repair, highlighting the importance of timely diagnosis and intervention 1, 2.