In a patient with shortness of breath and a confirmed diagnosis of Atrial Septal Defect (ASD) secundum, is a left or right heart catheterization indicated?

Right Heart Catheterization is Indicated for ASD Secundum with Shortness of Breath

In a patient with shortness of breath and confirmed ASD secundum by TEE with bubble study, right heart catheterization is indicated to assess pulmonary artery pressures and pulmonary vascular resistance before making closure decisions, unless the patient is young with clearly normal pulmonary pressures on noninvasive imaging. 1, 2

When Right Heart Catheterization is Required

Right heart catheterization must be performed in the following scenarios before proceeding with ASD closure:

• Elevated or uncertain pulmonary artery pressures on echocardiography, specifically when PA systolic pressure appears ≥50% of systemic pressure or pulmonary vascular resistance may be >1/3 systemic resistance 1, 2
• Adults over 40 years old, regardless of echo findings, due to frequent acquired left ventricular diastolic dysfunction that can paradoxically worsen after ASD closure 1, 2
• Symptomatic patients with shortness of breath where the mechanism is unclear or pulmonary pressures appear elevated 1, 2
• Discrepant or inconclusive noninvasive imaging data that does not clearly demonstrate right ventricular volume overload, shunt magnitude, or pulmonary pressures 2

When Right Heart Catheterization Can Be Avoided

Diagnostic catheterization is not routinely indicated (Class III recommendation) when all of the following criteria are met 1, 2:

• Patient is young (typically <40 years)
• TEE clearly demonstrates defect morphology and right ventricular volume overload
• Echocardiography shows adequate estimation of pulmonary artery pressures that are clearly normal (<50% systemic)
• Shunt magnitude is clearly assessed (Qp:Qs ≥1.5:1)
• No exercise-induced desaturation is present

Critical Hemodynamic Thresholds That Require Catheterization

The decision to close an ASD depends on specific hemodynamic parameters that can only be accurately measured by right heart catheterization 3, 1:

• Closure is indicated when PA systolic pressure is <50% of systemic pressure AND pulmonary vascular resistance is <1/3 systemic resistance 3, 1
• Closure may be considered when PA systolic pressure is 50-67% of systemic pressure OR pulmonary vascular resistance is 1/3 to 2/3 systemic resistance 3
• Closure is contraindicated when PA systolic pressure is >2/3 systemic OR pulmonary vascular resistance is >2/3 systemic OR net right-to-left shunt is present 3, 1, 4

Practical Algorithm for Your Patient

For a patient presenting with shortness of breath and confirmed ASD secundum by TEE:

1. First, assess age and echo findings 1, 2:

   • Is the patient >40 years old? → Proceed to right heart catheterization
   • Does echo show PA pressure >50% systemic? → Proceed to right heart catheterization
   • Is there exercise-induced desaturation? → Proceed to right heart catheterization

2. If patient is young (<40) with reassuring echo 1, 2:

   • Clear RV enlargement present
   • PA pressures clearly <50% systemic
   • Qp:Qs ≥1.5:1
   • No desaturation → Can proceed directly to closure planning without diagnostic catheterization

3. If any uncertainty exists → Perform right heart catheterization 1, 2

Common Pitfalls to Avoid

The most critical pitfall is proceeding to ASD closure without catheterization in patients with elevated pulmonary pressures. Closure with established severe pulmonary vascular disease causes acute right ventricular failure and is fatal 4. The presence of shortness of breath in your patient raises concern for either pulmonary hypertension or other cardiopulmonary pathology that requires hemodynamic clarification 1.

Adults over 40 frequently have acquired left ventricular diastolic dysfunction that may not be apparent on standard echocardiography but becomes clinically significant after ASD closure when the left ventricle suddenly receives increased preload 1, 2. This is why catheterization is recommended regardless of echo findings in this age group.

Echocardiographic estimation of pulmonary pressures can be inaccurate, particularly when tricuspid regurgitation is absent or minimal, making direct measurement via catheterization essential when closure decisions hinge on these values 1, 2, 5.

Why Right Heart Catheterization Specifically

Right heart catheterization (not left heart catheterization) is the appropriate procedure because it directly measures 3, 1, 6:

• Mean pulmonary artery pressure
• Pulmonary artery wedge pressure
• Pulmonary vascular resistance
• Cardiac output and shunt calculation (Qp:Qs ratio)
• Right ventricular pressures and function

These measurements are essential to determine whether the ASD can be safely closed and to exclude pulmonary arterial hypertension that would contraindicate closure 3, 1, 4.