What is the management approach for a patient with an atrial septal defect (ASD)?

Management of Atrial Septal Defect

Diagnostic Approach

ASD diagnosis requires imaging demonstration of the defect with evidence of right ventricular volume overload, followed by assessment of hemodynamic significance to determine closure candidacy. 1

Essential Diagnostic Studies

• Transthoracic echocardiography (TTE) is the primary imaging modality to visualize the defect location (secundum, primum, sinus venosus, coronary sinus), demonstrate left-to-right shunting with color Doppler, and assess RV enlargement 1
• Transesophageal echocardiography (TEE), cardiac MRI, or cardiac CT are required to evaluate pulmonary venous connections and precisely measure defect size and septal rims for device closure planning 1
• Pulse oximetry at rest and during exercise is mandatory to detect right-to-left shunting (cyanosis), which would contraindicate closure 1
• Echocardiographic assessment must quantify the Qp:Qs ratio (pulmonary-to-systemic blood flow), RV size/function, and estimate pulmonary artery pressures 1

When Cardiac Catheterization is Needed

• Cardiac catheterization is reasonable when pulmonary hypertension is suspected or noninvasive data are equivocal, to directly measure PA pressures and calculate pulmonary vascular resistance 1
• Catheterization is NOT indicated in younger patients with uncomplicated ASD when noninvasive imaging is adequate 1
• Vasoreactivity testing during catheterization should be performed in patients with elevated PA pressures to assess candidacy for closure 1

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Indications for ASD Closure

Class I Recommendations (Must Close)

Closure (percutaneous or surgical) is indicated for secundum ASD causing RV enlargement and Qp:Qs ≥1.5:1 in symptomatic patients, provided PA systolic pressure is <50% of systemic pressure and PVR is <1/3 systemic vascular resistance. 1, 2

• This applies to patients with impaired functional capacity, fatigue, exercise intolerance, or frequent respiratory infections 1
• The goal is to reduce RV volume overload and improve exercise tolerance before irreversible complications develop 1

Primum ASD, sinus venosus defects, and coronary sinus defects require surgical repair (not amenable to percutaneous closure) when causing RV enlargement and Qp:Qs ≥1.5:1, using the same hemodynamic thresholds 1, 3

Class IIa Recommendations (Reasonable to Close)

Closure is reasonable in asymptomatic adults with secundum ASD when RV enlargement and Qp:Qs ≥1.5:1 are present, meeting the same hemodynamic criteria (PA pressure <50% systemic, PVR <1/3 systemic) 1, 2

• Natural history data show that Qp:Qs increases over time in medium-sized ASDs during childhood and adolescence, with progressive RV volume overload 4
• Delaying closure based on absence of symptoms is a critical pitfall, as symptoms lag behind objective cardiopulmonary dysfunction 3
• Nearly 25% of patients with unoperated ASDs die before age 27, and 90% by age 60 3

Surgical closure during another cardiac procedure is reasonable when Qp:Qs ≥1.5:1 and RV enlargement are present, even if the ASD was not the primary surgical indication 1, 2

Special Indications

Closure may be considered for paradoxical embolism or documented orthodeoxia-platypnea syndrome, even with smaller shunts 1, 2

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Absolute Contraindications to Closure

Do NOT close the ASD when:

• PA systolic pressure >67% of systemic pressure 2
• PVR >2/3 of systemic vascular resistance 2
• Net right-to-left shunt at rest (Eisenmenger physiology) 2
• Cyanosis at rest or during exercise 1

Closing an ASD with established severe pulmonary vascular disease causes acute RV failure and death. 2 This is the most critical assessment before any closure procedure.

Borderline Pulmonary Hypertension

When PA systolic pressure is 50-67% of systemic and PVR is 1/3 to 2/3 of systemic resistance, closure may be considered only after careful evaluation by pulmonary hypertension specialists with expertise in congenital heart disease 2, 3

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Closure Method Selection

Percutaneous Device Closure

Transcatheter device closure is preferred for secundum ASD when anatomically suitable, as it is less invasive with excellent outcomes 3, 5

• 3D-TEE is essential to guide device selection, measure defect size, and assess adequacy of septal rims 1, 6
• The correlation between 3D-TEE and balloon-stretched diameter is excellent for single defects (r=0.85) but poor for multiple defects (r=0.45) 6
• Echocardiographic imaging during the procedure is required to guide device deployment 1

Surgical Closure

Surgical repair is mandatory for:

• Primum ASD, sinus venosus defects, and coronary sinus defects (not amenable to device closure) 1, 3
• Secundum ASD with inadequate septal rims for device placement 1
• Concomitant tricuspid valve repair/replacement 1
• Associated cardiac lesions requiring surgical correction 1

Surgery should be performed by surgeons with training and expertise in congenital heart disease. 1 Early mortality is approximately 1% in the absence of PAH or major comorbidities 3

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Medical Management

Small ASDs Not Requiring Closure

ASDs <5 mm without RV volume overload do not require closure unless paradoxical embolism occurs 2, 3

• Follow-up echocardiography every 2-3 years to assess RV size, function, and PA pressure 1
• Monitor for symptoms, particularly arrhythmias and paradoxical embolic events 1
• Critical pitfall: In older adults, acquired conditions (hypertension, coronary disease, valvular disease) reduce LV compliance and increase left-to-right shunting, making previously insignificant ASDs hemodynamically relevant 1, 2

Arrhythmia Management

Atrial arrhythmias (flutter, fibrillation) should be treated to restore and maintain sinus rhythm. 1

• Cardioversion after appropriate anticoagulation is recommended if atrial fibrillation occurs 1
• Rate control and anticoagulation are required if sinus rhythm cannot be maintained 1
• Atrial arrhythmias result from long-standing RV volume and pressure overload 1

Heart Failure Management

ACE inhibitors and/or diuretics may be indicated in patients with AV valve regurgitation and symptoms of chronic heart failure 1

Pulmonary vasodilator therapy (endothelin-receptor antagonists, PDE-5 inhibitors) may be indicated in patients with PAH and no significant left-to-right shunt who are deemed high-risk for surgical repair, but this requires extreme caution 1

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Post-Closure Monitoring

After device or surgical closure, monitor for:

• Postpericardiotomy syndrome: fever, fatigue, vomiting, chest pain, or abdominal pain suggesting pericardial effusion/tamponade 3
• Echocardiography to assess device position/stability, residual shunting, pericardial effusion, and RV function 3
• Expected improvements: NYHA functional class, RV systolic pressure, RV volumes and dimensions 3

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Timing Considerations

Surgery performed after age 25 years results in reduced survival compared to age-matched controls, emphasizing the importance of earlier intervention 3, 5

Closure before age 25 is associated with normal life expectancy, while untreated defects reduce life expectancy with increasing rates of exercise intolerance, atrial arrhythmias, RV dysfunction, and pulmonary hypertension with advancing age 5, 7