When to Close an Atrial Septal Defect (ASD)
Close an ASD when there is right atrial and/or right ventricular enlargement with a hemodynamically significant left-to-right shunt (Qp:Qs ≥1.5:1), provided pulmonary pressures and vascular resistance are not prohibitively elevated. 1
Primary Indications for Closure
Symptomatic Patients with Secundum ASD (Class I Recommendation)
Closure is definitively indicated for adults with isolated secundum ASD who have:
- Impaired functional capacity (symptoms) 1
- Right atrial and/or RV enlargement 1
- Qp:Qs ≥1.5:1 (hemodynamically significant shunt) 1
- No cyanosis at rest or exercise 1
- PA systolic pressure <50% of systemic pressure 1
- PVR <1/3 systemic vascular resistance 1
This represents the strongest recommendation from the 2018 AHA/ACC guidelines, with the goal of reducing RV volume and improving exercise tolerance. 1
Asymptomatic Patients with Secundum ASD (Class IIa Recommendation)
Closure is reasonable even in asymptomatic adults when:
- Right atrial and RV enlargement is present 1
- Qp:Qs ≥1.5:1 1
- Same hemodynamic criteria as above (PA pressure <50% systemic, PVR <1/3 systemic) 1
The rationale is to prevent long-term complications including atrial arrhythmias, progressive RV dysfunction, and pulmonary vascular disease that develop in 5-10% of patients. 1, 2 Research demonstrates that closure in adults >40 years results in decreased RV dimensions and symptomatic improvement. 3
Non-Secundum ASDs (Class I Recommendation)
Surgical repair is indicated for primum ASD, sinus venosus defect, or coronary sinus defect when:
- Same hemodynamic criteria apply (impaired function, RV enlargement, Qp:Qs ≥1.5:1) 1
- These defects are not amenable to percutaneous closure and require surgical intervention 1, 2
Critical Hemodynamic Thresholds
Borderline Pulmonary Hypertension (Class IIb - May Consider)
Closure may be considered when: 1
- Qp:Qs ≥1.5:1 AND
- PA systolic pressure 50-67% of systemic OR
- PVR 1/3 to 2/3 of systemic resistance
This requires careful evaluation by pulmonary hypertension specialists, as the risk-benefit ratio becomes less favorable. 1
Absolute Contraindications (Class III - Harm)
Do NOT close the ASD when: 1
- PA systolic pressure >2/3 systemic OR
- PVR >2/3 systemic resistance OR
- Net right-to-left shunt (Eisenmenger physiology)
Closure in these circumstances causes clinical deterioration and is contraindicated. 1
Special Clinical Scenarios
Small ASDs
Do not close defects <5 mm without RV volume overload, as they do not impact natural history. 1, 2 The exception is paradoxical embolism, where closure is reasonable regardless of size. 1
Concomitant Cardiac Surgery
Surgical closure is reasonable during another cardiac procedure if Qp:Qs ≥1.5:1 and RV enlargement are present, even if the ASD was not the primary indication for surgery. 1
Critical Pitfalls to Avoid
Never assume small shunts are benign in older adults - acquired conditions (hypertension, coronary disease, valvular disease) can increase left-to-right shunting over time, making previously insignificant ASDs hemodynamically relevant. 1
Always exclude severe PAH before closure - this is the most critical assessment, as closure with established severe pulmonary vascular disease causes acute RV failure and death. 1 Pulse oximetry at rest and with exercise helps identify patients with elevated PVR and shunt reversal. 1
Recognize that age alone is not a contraindication - closure benefits extend to elderly patients, with research showing successful outcomes in patients >40 years and even into the 8th decade. 3, 4
Closure Method Selection
Percutaneous device closure is preferred for secundum ASDs when anatomically suitable, offering equivalent efficacy to surgery with shorter hospital stays and faster recovery. 2, 5 Devices up to 40mm can be safely deployed for large defects (24-39mm), though careful technique is required. 6
Surgical closure is mandatory for sinus venosus, primum, and coronary sinus defects, as these are not amenable to transcatheter techniques. 1, 2, 5