Referral to Cardiology for Intracardiac Shunt Found on TTE
Yes, you should refer this patient to cardiology, specifically to an Adult Congenital Heart Disease (ACHD) specialist if available, as intracardiac shunts require specialized evaluation to determine hemodynamic significance, assess for complications, and guide management decisions including potential closure. 1
Why Cardiology Referral is Essential
Intracardiac shunts are among the most common cardiac lesions in adults with congenital heart disease and require specialized assessment beyond initial TTE findings. 2 The detection of an intracardiac shunt on TTE is only the beginning of the diagnostic workup—not the end.
Key Reasons for Specialist Involvement:
Hemodynamic assessment is required to determine shunt magnitude (Qp:Qs ratio), pulmonary artery pressures, and right heart volume overload, which cannot be fully assessed by TTE alone 1
Additional imaging is typically needed because TTE has significant limitations in adults—poor visualization of the superior and posterior atrial septum, inability to adequately assess pulmonary venous connections, and limited assessment of atrial rim adequacy for potential device closure 1
Risk stratification for complications including paradoxical embolism, atrial arrhythmias, pulmonary arterial hypertension, and Eisenmenger syndrome requires specialized expertise 1
What the Cardiologist Will Do
Advanced Diagnostic Evaluation:
Transesophageal echocardiography (TEE) provides superior visualization of the entire atrial septum (51% sensitivity vs 32% for TTE), pulmonary venous connections, and can identify anomalous drainage patterns that TTE misses 1, 3, 4
Cardiac MRI or cardiac CT is ideal for delineating pulmonary venous anatomy, quantifying shunt fraction, and assessing right ventricular volumes and function without ionizing radiation (for MRI) 1
Cardiac catheterization may be necessary to determine detailed hemodynamics, measure pulmonary vascular resistance, and clarify discrepant or inconclusive noninvasive data before making treatment decisions 1
Treatment Decision-Making:
Closure indications depend on multiple factors: shunt size, right heart volume overload, pulmonary artery pressures, symptoms, history of paradoxical embolism, and presence of pulmonary hypertension 1
Device vs surgical closure requires assessment of defect morphology, size, rim adequacy, and associated anomalies—decisions that require ACHD expertise 1
Contraindications to closure must be identified, particularly severe pulmonary arterial hypertension with shunt reversal (Eisenmenger physiology), which would make closure harmful 1
Critical Clinical Context That Affects Urgency
Refer Urgently (Within Days) If:
History of stroke or TIA (especially cryptogenic)—the shunt may have caused paradoxical embolism and closure could prevent recurrence 3, 4
Hypoxemia with oxygen saturation <90% at rest or with exertion—suggests significant right-to-left shunting or pulmonary hypertension 1
Signs of right heart failure—peripheral edema, elevated jugular venous pressure, hepatomegaly 1
Concurrent pulmonary embolism—presence of intracardiac shunt significantly increases risk of death (relative risk 2.4), stroke (relative risk 5.9), and peripheral arterial embolism (relative risk 15) 1
Routine Referral (Within Weeks) If:
Asymptomatic patient with incidental finding on TTE 1
No history of embolic events or unexplained hypoxemia 1
Common Pitfalls to Avoid
Do not assume the shunt is "small" or "insignificant" based on TTE alone—TTE systematically underestimates shunt severity compared to TEE and cannot adequately assess many anatomic features critical for management 1, 5
Do not order a "bubble study" yourself without cardiology input—while bubble studies help detect and semi-quantify shunts, the cardiologist will determine the appropriate timing and technique (TTE vs TEE) based on clinical context 3, 4
Do not delay referral waiting for symptoms to develop—patients with moderate-to-large shunts who don't undergo closure have worse long-term outcomes including more atrial arrhythmias, reduced functional capacity, and progressive pulmonary hypertension 1
Do not assume all shunts need closure—some patients have contraindications (severe pulmonary hypertension with reversed shunting) where closure would be harmful, which is why specialist evaluation is essential 1
Special Populations Requiring Heightened Attention
Women of childbearing age—pregnancy significantly increases hemodynamic burden and shunt-related complications; pre-pregnancy counseling by ACHD specialist is critical 1
Patients with unexplained dyspnea on exertion—exercise testing with pulse oximetry may reveal shunt-related desaturation not apparent at rest 1
Older adults (>40 years)—must be evaluated for left atrial hypertension from diastolic dysfunction, which may cause similar symptoms but could worsen with shunt closure 1