What is the recommended workup and management for a 6-year-old child with a new diagnosis of Atrial Septal Defect (ASD)?

Workup for New Diagnosis of ASD in a 6-Year-Old

For a 6-year-old with newly diagnosed atrial septal defect, proceed with comprehensive echocardiography to define defect type, size, location, and assess for right ventricular volume overload—the key determinant of hemodynamic significance—along with ECG and chest X-ray, while reserving cardiac catheterization only for cases with elevated pulmonary artery pressure on echo. 1

Initial Diagnostic Evaluation

Echocardiography (Primary Diagnostic Tool)

Transthoracic echocardiography is the cornerstone diagnostic test and must assess the following specific parameters: 1

• Defect characteristics: Type (secundum, primum, sinus venosus, coronary sinus), exact size in millimeters, and precise location 1
• Hemodynamic significance: Presence and degree of right ventricular volume overload (this is more important than shunt ratio for determining clinical significance) 1
• Shunt quantification: Direction of shunt and Qp:Qs ratio (pulmonary-to-systemic flow ratio) 1
• Right heart assessment: Right atrial size, right ventricular size and function, tricuspid regurgitation severity 1
• Pulmonary artery pressure: Estimated PA systolic pressure to screen for pulmonary hypertension 1
• Associated anomalies: Pulmonary venous connections (especially for sinus venosus defects), mitral valve cleft (in primum ASD), other structural abnormalities 1

For sinus venosus defects specifically, transesophageal echocardiography may be required for accurate diagnosis and assessment of pulmonary venous drainage, as these are frequently missed on routine transthoracic imaging. 1, 2

Electrocardiogram

Obtain a 12-lead ECG to identify type-specific patterns: 1, 2

• Secundum ASD: Look for incomplete right bundle branch block (rSR' pattern in V1), right axis deviation (mean QRS axis ~108 degrees), and tall peaked P waves in leads II, III, aVF indicating right atrial enlargement 2
• Primum ASD: Superior left axis deviation is the distinguishing feature, along with incomplete RBBB and possible first-degree AV block 2
• Sinus venosus ASD: Abnormal P-wave axis (superiorly directed, often negative in inferior leads) due to superior location near SVC 2

Critical caveat: Absence of typical ECG findings does not exclude hemodynamically significant ASD, as only 57% of patients with significant defects show ECG criteria for right ventricular enlargement. 2

Chest X-Ray

Obtain to assess for increased pulmonary vascular markings (often overlooked but indicates significant left-to-right shunt) and cardiomegaly. 1

When Cardiac Catheterization IS Indicated

Cardiac catheterization should be performed when: 1

• Echocardiography demonstrates elevated pulmonary artery pressure to measure pulmonary vascular resistance index (PVRI) and determine operability 1
• PVRI measurement is critical if PA systolic pressure appears elevated, as repair decisions depend on whether PVRI is <6 Wood units·m² or PVR/SVR <0.3 1

When Cardiac Catheterization IS NOT Indicated

Do not perform diagnostic cardiac catheterization in younger patients with uncomplicated ASD when noninvasive imaging (echocardiography) provides adequate information. 1 This is a Class III recommendation (should not be done).

Management Algorithm Based on Findings

If Right Ventricular Volume Overload Present (Hemodynamically Significant)

Closure is indicated regardless of symptoms when there is evidence of RV volume overload and PVR <5 Wood units. 1, 3

• Secundum ASD: Device closure is the preferred method if anatomically suitable (stretched diameter <38mm with adequate rim ≥5mm) 1, 3
• Primum, sinus venosus, or coronary sinus ASD: Surgical repair required as these are not amenable to device closure 3, 4
• Optimal timing: Closure typically performed at 4-5 years of age in asymptomatic patients, but at 6 years with RV volume overload, proceed without delay 4

If Small Defect Without RV Volume Overload

For defects ≤5-6mm without RV enlargement: 1, 5

• No intervention required initially 1
• Serial echocardiographic follow-up every 2-3 years to monitor RV size, function, and pulmonary pressure 1
• Monitor for symptoms including arrhythmias and paradoxical embolic events 1
• Spontaneous closure occurs in 81% of small defects in this age group 5

If Pulmonary Hypertension Detected

When echo suggests elevated PA pressure: 1

• Proceed to cardiac catheterization to measure PVRI 1
• If PVRI <6 WU·m² or PVR/SVR <0.3: Repair should be performed 1
• If PVRI ≥6 WU·m² or PVR/SVR ≥0.3 with minimal AVT responsiveness: Repair is contraindicated; consider PAH-targeted therapy with repeat catheterization in 4-6 months 1

Critical Pitfalls to Avoid

Do not delay closure based on absence of symptoms. Symptoms lag behind objective cardiopulmonary dysfunction and cannot guide therapy—25% of unoperated patients die before age 27, and outcome is best with repair before age 25. 3

Do not miss sinus venosus defects. These are frequently overlooked due to their superior location and require careful assessment of pulmonary venous drainage, often with TEE. 1, 2

Do not perform maximal exercise testing if severe pulmonary hypertension is present (Class III recommendation). 1

Do not assume all secundum defects can undergo device closure. Verify anatomic suitability including defect size and adequate rims before planning percutaneous approach. 1, 3