What are the considerations for transcatheter closure of large atrial septal defects (ASDs) greater than 40 mm in size?

Transcatheter Closure of Large ASDs >40 mm

For ASDs ≥40 mm, surgical closure should be strongly preferred over transcatheter closure, as procedural success rates drop dramatically to only 17% with significantly higher complication rates including device embolization. 1

Size-Based Treatment Algorithm

ASDs 20-39 mm

• Transcatheter closure is highly successful (97% success rate) and should be the preferred approach when anatomically suitable with adequate rims 1
• Device closure is recommended for secundum ASDs with stretched diameter <38 mm and adequate rim ≥5 mm in most locations 2, 3
• The majority of secundum ASDs can be closed percutaneously when appropriate morphology exists 4

ASDs ≥40 mm (Extremely Large Defects)

• Surgical closure is strongly recommended as the primary treatment modality 1
• Transcatheter closure success rate plummets to only 17% (1 out of 6 patients) in this size range 1
• Device embolization and other major complications are significantly more common, particularly during the learning curve period 1, 5
• When transcatheter closure is not feasible or appropriate, surgical closure should be performed 4

Critical Anatomic Considerations Beyond Size

A single diameter measurement does not adequately reflect true ASD size, as many defects are oval or crescentric rather than round 6. Key anatomic factors include:

• Rim adequacy: Presence or absence of aortic rim does not significantly influence procedural success for defects <40 mm, but deficient postero-inferior rims increase complication risk 1
• Septal aneurysm or multifenestrated septum: Requires careful evaluation and consultation with interventional cardiologists before device closure 4
• 3-dimensional imaging is essential for proper defect characterization rather than relying solely on maximum diameter 6

Modified Techniques for Large Defects

For defects in the 30-39 mm range where transcatheter closure is attempted:

• Balloon-assisted technique (BAT) can facilitate successful device deployment by supporting the left atrial disk and preventing prolapse into the right atrium 6, 7
• BAT has demonstrated successful closure of defects up to 40 mm in selected cases, though this remains at the extreme limit of feasibility 7
• Experience matters significantly—complication rates decline substantially after the initial learning curve 5

Hemodynamic Prerequisites for Any Closure

Regardless of size or technique, closure should only proceed when:

• Qp:Qs ≥1.5:1 with evidence of RV volume overload 2, 3
• PA systolic pressure <50% of systemic pressure 2
• PVR <1/3 systemic resistance (<5 Wood units) 2
• Net left-to-right shunt is present 2

Absolute Contraindications

Do not close ASDs in patients with:

• Severe irreversible pulmonary arterial hypertension with no evidence of left-to-right shunt (Eisenmenger physiology) 4, 3
• PA systolic pressure >2/3 systemic pressure 3
• Net right-to-left shunt 3

Surgical Approach for Large Defects

When surgical closure is performed for large ASDs:

• Early mortality is approximately 1% in the absence of PAH or major comorbidities 4, 2
• Pericardial patch closure or direct suture closure are standard techniques 4
• Concomitant tricuspid valve repair should be performed for significant regurgitation 4
• Long-term outcomes are excellent with symptom improvement 4

Common Pitfalls to Avoid

• Attempting transcatheter closure of defects ≥40 mm leads to high failure rates and increased complications 1
• Relying solely on 2D measurements without 3D imaging assessment may underestimate true defect complexity 6
• Proceeding without adequate experience with large device deployment increases complication risk, particularly device embolization 5
• Ignoring deficient rims in the postero-inferior region increases risk of device dislodgement 1

Post-Procedure Monitoring

For any ASD closure (transcatheter or surgical):

• Monitor immediately for postpericardiotomy syndrome symptoms: fever, fatigue, vomiting, chest pain, or abdominal pain requiring urgent echocardiography to assess for tamponade 2, 3
• Evaluate for device migration, erosion, or other complications at 3 months 4
• Annual follow-up is recommended if PAH, atrial arrhythmias, or ventricular dysfunction persist 4