What is the management approach for a patient with a left to right intraatrial shunt?

Management of Left-to-Right Intraatrial Shunt

Closure is indicated for hemodynamically significant left-to-right intraatrial shunts when right atrial and right ventricular enlargement are present, regardless of symptoms, with percutaneous device closure preferred for secundum defects and surgical closure required for all other anatomic subtypes. 1, 2

Initial Diagnostic Assessment

Hemodynamic Evaluation Required

• Confirm hemodynamic significance by demonstrating Qp:Qs ≥1.5:1 with right ventricular enlargement on echocardiography 1, 2
• Measure pulmonary artery systolic pressure and pulmonary vascular resistance via cardiac catheterization, particularly in older adults or when pulmonary hypertension is suspected 1, 2
• Perform resting and ambulatory pulse oximetry to identify dynamic shunt reversal with exercise 1
• Assess for left atrial hypertension from diastolic dysfunction in older adults, as closure may worsen symptoms if the left atrium can no longer decompress into the right atrium 1

Anatomic Classification

• Identify defect type (secundum, primum, sinus venosus, coronary sinus) as this determines closure method 1, 2
• Evaluate for associated anomalies including anomalous pulmonary venous connections, atrioventricular valve abnormalities, and tricuspid regurgitation 1

Treatment Algorithm by Defect Type

Secundum ASD with Favorable Anatomy

• Percutaneous device closure is first-line treatment when right atrial and RV enlargement are present 1, 2
• Device closure achieves excellent success rates with minimal complications 1
• Baseline echocardiogram should be performed at least 72 hours post-procedure to assess hemodynamics and exclude complications (severe mitral regurgitation, LV dysfunction, residual shunt) 1

Secundum ASD Requiring Surgical Approach

• Surgical closure is indicated when concomitant tricuspid valve repair/replacement is needed (moderate or greater TR) or anatomy precludes percutaneous device use 1, 2
• Surgery should be performed by a congenital heart surgeon with expertise in adult congenital heart disease 1
• Consider concomitant tricuspid annuloplasty for moderate or greater TR to improve RV remodeling 1

Non-Secundum Defects

• Sinus venosus, coronary sinus, and primum defects require surgical closure—percutaneous closure is not appropriate 1, 2
• These defects have proximity to atrioventricular valves and conduction system, requiring surgical expertise 1
• Evaluate for anomalous pulmonary venous connections, which commonly accompany these defects 1

Critical Hemodynamic Thresholds for Closure

Indications for Closure

• Pulmonary artery systolic pressure <50% of systemic pressure 1, 2
• Pulmonary vascular resistance <1/3 of systemic resistance 1, 2
• Net left-to-right shunt with Qp:Qs ≥1.5:1 1, 2
• Right atrial and RV enlargement on imaging 1, 2

Absolute Contraindications to Closure

• Severe irreversible pulmonary arterial hypertension with no evidence of left-to-right shunt (Eisenmenger physiology with net right-to-left shunting)—morbidity and mortality are prohibitively high 1, 2
• Pulmonary artery systolic pressure >2/3 systemic pressure 1, 2
• Pulmonary vascular resistance >2/3 systemic vascular resistance 1, 2

Borderline Pulmonary Hypertension

• Closure may be considered when pulmonary pressure is elevated but persistent left-to-right shunting remains, with pretreatment using pulmonary arterial hypertension therapies 1
• Demonstrated reduction in pulmonary vascular resistance >20% with PAH therapies portends favorable prognosis after closure 1
• Consultation with both adult congenital heart disease and pulmonary hypertension specialists is essential for complex decision-making 1

Special Clinical Scenarios

Paradoxical Embolism or Orthodeoxia-Platypnea

• Closure is reasonable for documented paradoxical embolism or orthodeoxia-platypnea syndrome, even without significant hemodynamic shunt 1

Atrial Arrhythmias

• Treat atrial arrhythmias to restore and maintain sinus rhythm when possible 1
• Anticoagulation is mandatory for atrial fibrillation, both before and after closure 1
• Consider concomitant Maze procedure for intermittent or chronic atrial tachyarrhythmias at time of surgical closure 1
• Pre-closure ablation is reasonable for supraventricular tachycardia 2

Post-Percutaneous Valvotomy Iatrogenic ASD

• Small left-to-right shunts at the atrial level after percutaneous mitral balloon valvotomy close spontaneously over 6 months in the majority of cases 1
• Large atrial septal defects or severe mitral regurgitation should be considered for early surgery 1

Post-Closure Management

Immediate Post-Procedure Surveillance

• Evaluate for device migration, erosion, or other complications at 3 months to 1 year after device closure and periodically thereafter 1
• Monitor for postpericardiotomy syndrome (fever, fatigue, chest pain) with immediate echocardiography if symptoms develop 1

Long-Term Follow-Up

• Annual clinical follow-up is required if ASD was repaired in adulthood and the following persist: pulmonary arterial hypertension, atrial arrhythmias, RV or LV dysfunction, or coexisting valvular lesions 1
• Perform comprehensive echocardiography with recurrent symptoms to evaluate hemodynamics, pulmonary artery pressure, and exclude significant mitral regurgitation or residual shunt 1

Critical Pitfalls to Avoid

• Do not assume small shunts are benign in older adults—acquired conditions (diastolic dysfunction, valvular disease) can increase left-to-right shunting over time, making previously insignificant ASDs hemodynamically relevant 1, 2
• Always exclude severe pulmonary arterial hypertension before closure, as closure with established severe pulmonary vascular disease is fatal 1, 2
• Do not rely solely on echocardiography for pulmonary pressure assessment in borderline cases—invasive hemodynamic assessment remains the gold standard for evaluating pulmonary vasoreactivity and confirming closure candidacy 1
• Recognize that older adults may have left atrial hypertension from diastolic dysfunction that could worsen after ASD closure when the decompression pathway is eliminated 1