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Ebstein anomaly is a rare congenital heart disease (CHD). It involves a malformation of the tricuspid valve (TV) and the right ventricle (RV). The anomaly occurs in approximately 1 per 200,000 live births and accounts for less than 1% of all congenital heart defects. Ebstein anomaly is characterized by apical displacement of the tricuspid valve leaflets (primarily the septal and posterior leaflets) into the right ventricle, resulting in a malformed tricuspid valve, an atrialized portion of the right ventricle, and a small functional right ventricle. This anomaly often includes tricuspid regurgitation (TR), right atrial enlargement, and, in severe cases, associated defects like atrial septal defect (ASD) or patent foramen ovale (PFO). In neonates, severe forms can present with cyanosis/hypoxia, or hemodynamic instability, particularly when complicated by circular shunt physiology.
Circular shunting is a unique and critical phenomenon in some neonates with Ebstein anomaly, where blood flows in a cyclical, non-productive loop between the right heart, lungs, and left heart without effective systemic or pulmonary circulation. This occurs primarily in the presence of severe tricuspid regurgitation, a right-to-left inter-atrial shunt, right left to right patent ductus arteriosus, elevated pulmonary vascular resistance (PVR) favouring blood from from the PDA to reach the main pulmonary artery, and significant pulmonary insufficiency leading to MPA-RV flow.
Ebstein's anomaly has been associated with maternal lithium use during pregnancy, although most cases are sporadic. It is characterized by various degree of displacement of the tricuspid valve towards the apex of the RV, with the posterior and septal leaflets being displaced. This leads to "atrialization" of the RV segment included in the right atrium, with subsequent enlargement of the RA and decreased RV functional cavity. Ebstein's anomaly is associated with atrial septal defect, Wolff-Parkinson-White (and supra-ventricular tachycardia) and risk of strokes. Often, these patients present with an enlarged cardiac silhouette on chest radiography (“Wall to Wall" heart).
Severe Ebstein's can be associated with the "Circular shunt physiology" (or "Circle of death"), a flow physiology by which blood flow goes from Right to Left atrium (via the ASD/inter-atrial shunt), to the Left ventricle, to the Aorta, to the Pulmonary artery (by the PDA) to the right ventricle (by pulmonary insufficiency), to the right atrium (via the tricuspid regurgitation), to the left atrium by the ASD.
Circular shunt physiology in Ebstein:
Aorta → Ductus → Pulmonary artery → Pulmonary Insufficiency → Right Ventricle → Tricuspid insufficiency → Right atrium → Foramen Ovale → Left atrium → Mitral valve → Left ventricle → Aortic valve → Aorta → Ductus arteriosus (Learn more here, and here). It refers to a recirculating loop of blood that bypasses systemic perfusion, often involving the right atrium, right ventricle, pulmonary arteries, ductus arteriosus, aorta, and back into the right heart—creating a futile circulatory loop. In Ebstein anomaly, the tricuspid valve is displaced apically, leading to a massive right atrium and an often severely dysfunctional or hypoplastic right ventricle. This causes severe tricuspid regurgitation, elevated right atrial pressure, and ineffective forward flow into the pulmonary artery. The functional pulmonary atresia seen in severe cases occurs because the RV cannot generate enough pressure to open the pulmonary valve. Some have described the use of maternal NSAIDs as a way to constrict the fetal duct in an attempt to address this fatal physiology for the fetus / newborn. Article here on "Surgical Management of Neonatal Ebstein’s Anomaly Associated With Circular Shunt".
Effective pulmonary blood flow is significantly reduced due to the following mechanisms:
Low right ventricular (RV) output, resulting from decreased RV capacitance caused by atrialization of the RV.
Severe pulmonary valve insufficiency, which leads to regurgitation and further reduces forward flow.
As a result, the pulmonary artery (PA) is underfilled, and the ductus arteriosus (PDA) provides flow to the PA via a left-to-right shunt. However, this flow comes at the expense of systemic perfusion, effectively “stealing” blood from the systemic circulation. The PDA jet is directed toward the incompetent pulmonary valve, allowing blood to flow retrogradely from the PDA into the PA and back into the RV. Pulmonary vascular resistance (PVR) is typically elevated due to low pulmonary blood flow, which triggers reflex vasoconstriction in an attempt to preserve perfusion pressure. Additionally, hypoxemia and acidosis, which are often present, further raise PVR. This hemodynamic environment favors the abnormal circuit of flow: from the PDA to the PA, through the insufficient pulmonary valve, and into the RV. Some of the treatment strategies may involve: pulmonary vascular relaxation (iNO, oxygen exposure, titrated mechanical ventilation), restriction of the duct to break the circular shunt (NSAIDs or ligation), supporting the cardiac function in the context of acidosis, hypoxemia and likely low coronary perfusion pressure (high RA pressure in which the coronary sinus drains), while avoiding too much increase in PVR or SVR. As such, many of those infants require some low dose epinephrine, or milrinone (if the BP is not low).
More on Ebstein's anomaly by clicking here (outside article).
Key Anatomical Features:
Downward (apical) displacement of the septal and posterior leaflets of the tricuspid valve into the right ventricular cavity.
Failure of delamination of the septal and posterior leaflets from the underlying myocardium. This is the main pathophysiological abnormality.
Dilation of the atrialized portion of the right ventricle (aRV). This is the inlet portion of the RV that is functionally integrated with the right atrium. The wall of the aRV is often thinned.
Redundancy, fenestrations, and tethering of the anterior tricuspid leaflet. The anterior leaflet can be described as "sail-like" and may prolapse into the RV outflow tract (RVOT), potentially causing obstruction.
The remaining part of the RV (trabecular and outlet portions) constitutes the functional right ventricle (fRV). The size and function of the fRV vary.
The anatomical severity has a wide spectrum, from minimal displacement to severe forms where the RV cavity is significantly compromised. Classification systems like Carpentier's categorize the anomaly based on the size and function of the atrialized and functional RV and leaflet mobility. In neonates, an echocardiographic grading score by Celermajer et al. compares the area of the RA and aRV to the fRV and left heart.
Physiology and Hemodynamics:
The functional disturbances vary greatly depending on the severity of the malformation and associated anomalies. Key issues include tricuspid regurgitation (TR), right ventricular failure, and arrhythmias.
Tricuspid regurgitation occurs to varying degrees in almost all patients. Severe TR interferes with RV output and leads to increased right atrial pressure.
Elevated right atrial pressure can cause a right-to-left shunt through an atrial septal defect (ASD) or patent foramen ovale (PFO). PFOs often remain open due to high RA pressure. ASDs are present in approximately 30% of cases.
Reduced right ventricular output can lead to decreased pulmonary blood flow, particularly when pulmonary vascular resistance (PVR) is still elevated after birth.
Severe TR and an enlarged RA/aRV can compress the left ventricle (LV), reducing its filling and potentially impacting systemic output.
In severe cases, the RV may not generate sufficient pressure to open a morphologically normal pulmonary valve, leading to "functional pulmonary atresia". This is different from true anatomic atresia and requires different treatment. With functional pulmonary atresia, pulmonary blood flow relies on the ductus arteriosus (DA). Constriction of the DA can reduce pulmonary blood flow and worsen hypoxemia.
Associated Anomalies:
Besides ASD/PFO, Ebstein anomaly can be associated with other cardiac defects, although less commonly:
Pulmonary valve stenosis or atresia.
Ventricular septal defects (VSD).
Tetralogy of Fallot (TOF).
Transposition of the great arteries (TGA).
Atrioventricular canal defects.
Left-sided heart abnormalities, including mitral valve anomalies and LV dysfunction/dysplasia.
Fetal Presentation:
Ebstein anomaly is a common reason for fetal echocardiography. Severe forms diagnosed in utero may lead to cardiomegaly, hydrops fetalis (fetal and placental edema), tachyarrhythmias, and even fetal demise.
Neonatal Presentation:
Neonates with Ebstein anomaly may present with cyanosis, congestive heart failure due to TR, and marked cardiomegaly. Symptoms depend on the severity of the anomaly and the degree of right-to-left shunting. Severe forms can present with progressive cyanosis and hypoxemia as the DA constricts. The heart may be enlarged on examination. Murmurs vary and may be absent in severe cases.
Diagnostic Evaluation:
Echocardiography is essential for diagnosis. It allows assessment of valve morphology, leaflet displacement, severity of TR, size of the RV components, and associated defects. Differentiating functional from anatomical pulmonary atresia can be challenging but crucial for management.
Chest X-ray may show cardiomegaly, particularly involving the right atrium, although it can be normal in mild cases.
Electrocardiogram (ECG) is abnormal in most patients. It may show tall P waves (right atrial enlargement) and right bundle-branch block. PR interval prolongation is common (first-degree AV block).
Management in Neonates:
Management strategies in neonates depend on the severity and physiology at presentation.
Conservative medical management may be an option.
Maintenance of DA patency with prostaglandin E1 (PGE1) may be necessary if there is ductal-dependent pulmonary blood flow (e.g., with functional or anatomical pulmonary atresia).
Surgical options for severe neonatal Ebstein anomaly often involve single ventricle palliation, such as the Starnes procedure (right ventricular exclusion), which is associated with a high mortality rate. This commits the patient to a staged palliation pathway (Glenn, Fontan).
Tricuspid valve repair (like the cone reconstruction) is the mainstay of management in older children and adults, but exact indications and timing in neonates are debated.
Prognosis:
Mortality is highest in the neonatal period, approximately 25%, even with surgical intervention. Starnes procedure and subsequent single ventricle palliation yield a 10-year survival of about 80%. Predictors of death in neonates include the echocardiographic grade of severity, fetal presentation, and RVOT obstruction. Arrhythmias: Arrhythmias are common in Ebstein anomaly, even in neonates. Accessory pathways are present in a significant number of patients and increase the risk of protracted arrhythmias.
References
Khalid O, Awad S. Pediatric Electrocardiography. Cham: Springer International Publishing; 2016. Available from: https://doi.org/10.1007/978-3-319-26258-1
Dipchand AI, et al. Manual of Cardiac Care in Children. Cham: Springer Nature Switzerland AG; 2024. Available from: https://doi.org/10.1007/978-3-031-70973-9
Park IS. An Illustrated Guide to Congenital Heart Disease: From Diagnosis to Treatment – From Fetus to Adult. Singapore: Springer Nature Singapore Pte Ltd.; 2019. Available from: https://doi.org/10.1007/978-981-13-6978-0
Rudolph AM. Congenital Diseases of the Heart: Clinical-Physiological Considerations. 3rd ed. Chichester: Wiley-Blackwell; 2009.
Scientific Software Solutions. Ebstein’s Anomaly. PedHeart Resource. 2016. Available from: https://pcics.org/wp-content/uploads/Ebsteins-Anomaly.pdf
Singh DP, Hussain K, Horenstein MS, Mahajan K. Ebstein Anomaly and Malformation. Treasure Island (FL): StatPearls Publishing; 2025 Jan. Available from: https://www.ncbi.nlm.nih.gov/books/NBK534824/
Attenhofer Jost CH, Connolly HM, Dearani JA, Edwards WD, Danielson GK. Ebstein’s Anomaly. Circulation. 2007;115(2):277-85. Available from: https://doi.org/10.1161/CIRCULATIONAHA.106.619338
Pasqualin G, Boccellino A, Chessa M, Ciconte G, Marcolin C, Micaglio E, Pappone C, Sturla F, Giamberti A. Ebstein’s anomaly in children and adults: multidisciplinary insights into imaging and therapy. Heart. 2023 Oct 11. Available from: https://doi.org/10.1136/heartjnl-2023-322420 (Epub ahead of print)
Neumann S, Rüffer A, Sachweh J, Biermann D, Herrmann J, Jerosch-Herold M, Hazekamp M, Sinning C, Zengin E, Blankenberg S, Girdauskas E, Reichenspurner H, Kehl T, Müller G, Kozlik-Feldmann R, Rickers C. Narrative review of Ebstein’s anomaly beyond childhood: Imaging, surgery, and future perspectives. Cardiovasc Diagn Ther. 2021 Dec;11(6):1310-1323. Available from: https://cdt.amegroups.org/article/view/66625/html
Apical view indicating the enlarged right atrium with the abnormal implantation of the tricuspid valve
Apical view showing the tricuspid insufficiency.
Subcostal view showing the enlarged right atrium and the downward displacement of the tricuspid valve.
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