Ebstein Anomaly: Anatomy, Physiology, and Surgical Pathway

1. Core concept

Ebstein anomaly is a congenital malformation of the tricuspid valve–right ventricular unit, not simply a displaced valve. Its defining developmental error is failure of normal delamination of the tricuspid leaflets from the underlying right ventricular myocardium, most prominently affecting the septal and posterior leaflets. This results in apical displacement of the functional tricuspid orifice, variable leaflet tethering or “plastering” to the RV wall, an atrialized proximal RV, and a small functional RV of variable capacity [1,2]. (PubMed)

Accordingly, the lesion should be understood as a combined disorder of:

• Valve morphology
• Right ventricular geometry and function
• Right atrial volume/pressure load
• Atrial-level shunting
• Age-dependent cardiopulmonary physiology [1-3]. (PubMed)

2. Embryologic and anatomic basis

2.1 Delamination failure: the foundational lesion

In the normal heart, the tricuspid leaflets separate from the ventricular wall and develop a mobile subvalvular apparatus. In Ebstein anomaly, this delamination is incomplete, producing:

• Apical displacement of the septal/posterior leaflet hinge points
• Restricted leaflet mobility
• Leaflet adherence to the RV wall
• Variable chordal and papillary muscle abnormalities
• Distortion of the inlet portion of the right ventricle [1,2] (PubMed)

The valve may therefore appear large in tissue area yet function poorly, because competence depends not only on leaflet surface area, but on mobility, coaptation geometry, and ventricular support.

2.2 Chamber consequences

The proximal RV above the displaced functional valve becomes atrialized—thin-walled, poorly contractile, and hemodynamically incorporated into the right atrium. Distal to this is the functional RV, which may be adequate, marginal, or severely hypoplastic. Meanwhile, the right atrium often becomes massively enlarged because it receives both systemic venous return and severe tricuspid regurgitant volume [1,2]. (PubMed)

2.3 Associated lesions and rhythm substrate

Common associated lesions include:

• PFO/ASD
• Severe tricuspid regurgitation (TR)
• Pulmonary valve dysfunction or functional pulmonary atresia
• Accessory pathways and supraventricular tachyarrhythmias
• Less commonly, other congenital lesions such as VSD or left-sided abnormalities [1,2] (PubMed)

This explains why Ebstein anomaly ranges from a critically ill cyanotic neonate to an incidentally diagnosed adult. The anatomy is heterogeneous, and the physiology is highly stage-dependent [1,2].

3. Pathophysiology changes with age

A central teaching point is that Ebstein physiology is not static. The same anatomic lesion behaves differently in the fetus, neonate, infant, child, and adult. Contemporary management therefore relies less on a single morphologic label and more on the interaction between:

1. Severity of TR
2. Size and contractile capacity of the functional RV
3. Pulmonary vascular resistance (PVR)
4. Presence and direction of atrial-level shunting
5. Pulmonary valve competence and RV-PA forward flow
6. Clinical stability and trajectory over time [2,3] (PubMed)

4. Neonatal physiology without a ductus: high-PVR, low-forward-flow state

In the immediate postnatal period, PVR is physiologically high. In a neonate with severe Ebstein anomaly, the combination of severe TR, a small functional RV, and high afterload to the pulmonary circuit may severely limit effective antegrade pulmonary blood flow. Right atrial pressure rises, and blood preferentially crosses the atrial septum right-to-left, producing cyanosis [3]. (PubMed)

Hemodynamic sequence

1. RV systolic output is lost backward because of severe TR.
2. The remaining functional RV may be too small or inefficient to sustain RV-to-PA forward flow.
3. Elevated RA pressure promotes right-to-left shunting across the PFO/ASD.
4. Systemic oxygen saturation falls.

This neonatal cyanosis is therefore not simply “valve leakage.” It is a combined problem of RV inefficiency, TR, high PVR, and atrial decompression physiology [1,3]. (PubMed)

A practical point is that some neonates improve as PVR falls over the first hours to days of life. This is why early management often includes intensive stabilization and serial reassessment rather than immediate uniform surgery in every symptomatic newborn [3].

5. Neonatal physiology with a PDA: functional pulmonary atresia and circular shunt

5.1 Functional pulmonary atresia

In the sickest neonates, the RV may fail to generate effective opening of the pulmonary valve despite the absence of true anatomic atresia. This creates functional pulmonary atresia, in which pulmonary blood flow becomes largely ductal-dependent rather than RV-driven [3,4]. (PubMed)

5.2 Circular shunt: the most dangerous physiology

The most lethal hemodynamic pattern is the circular shunt. In this situation:

• Blood passes from the aorta through the PDA into the pulmonary arteries
• It regurgitates through an incompetent pulmonary valve back into the RV
• Severe TR returns it to the RA
• It crosses the atrial septum and re-enters the systemic circulation

This creates a recirculating loop that consumes systemic output without efficiently supporting systemic perfusion, leading to systemic steal, profound hemodynamic instability, and high mortality if not interrupted [3,4]. (PubMed)

This is the critical reason why prostaglandin is not automatically beneficial in every neonatal Ebstein patient. In some patients, ductal patency supports pulmonary blood flow; in others, especially with circular shunt physiology, it worsens systemic compromise. Management must therefore be physiology-driven, not protocol-driven [3,4]. (PubMed)

6. Physiology after infancy

Once PVR normalizes, many patients transition from a ductal-dependent cyanotic state to a chronic volume-overload state. At that stage, antegrade pulmonary flow is often present, and the dominant pathophysiology becomes:

• Persistent moderate/severe TR
• Progressive RA and RV dilation
• Ongoing atrial-level shunting if RA pressure remains elevated
• Reduced exercise tolerance
• Increasing arrhythmia burden [1,2] (PubMed)

Thus, the post-infancy problem is usually not circulatory collapse, but rather the long-term consequences of chronic right-sided volume load: chamber enlargement, ventricular interdependence, reduced functional reserve, cyanosis in selected patients, and rhythm-related morbidity [1,2]. (PubMed)

7. Clinical phenotypes: a practical surgeon-facing framework

A useful framework is to think of Ebstein anomaly in three major phenotypes.

7.1 Critically ill neonate

Typical features:

• Severe TR
• Tiny functional RV
• Functional pulmonary atresia
• Ductal dependence
• Circular shunt and/or cardiogenic shock

This group requires urgent hemodynamic rescue and often cannot tolerate a conventional “wait and see” approach [3,4]. (PubMed)

7.2 Infant/child with salvageable RV and reparable valve

Typical features:

• Some meaningful antegrade RV-to-PA flow
• Less extreme RV hypoplasia
• Valve tissue suitable for reconstruction
• TR-driven volume overload rather than pure neonatal collapse

This group is the principal substrate for biventricular repair, especially cone reconstruction [5,6]. (PubMed)

7.3 Older child/adult with chronic TR, dilation, cyanosis, and/or arrhythmia

Typical features:

• Progressive severe TR
• RA/RV enlargement
• Reduced exercise tolerance
• Cyanosis in the presence of atrial-level shunting
• Arrhythmia burden

In these patients, contemporary management generally favors repair before the onset of irreversible ventricular dysfunction or advanced rhythm complications [1,2]. (PubMed)

8. Starnes procedure: rationale, indications, and physiologic goal

The Starnes procedure remains the classic rescue operation for the most severe neonatal phenotype. Contemporary thinking increasingly views it not merely as an endpoint toward Fontan circulation, but often as a stabilizing bridge that buys time for later reassessment [3,10]. (PubMed)

Indications

The strongest indications include:

• Extreme Ebstein morphology
• Tiny functional RV
• Severe TR
• Poor RV-generated forward flow
• Functional pulmonary atresia
• Circular shunt
• Refractory cyanosis or cardiogenic shock [3,4] (PubMed)

Operative principle

The operation is designed to:

1. Exclude the failing RV from the circulation
2. Eliminate severe TR as a major energy sink
3. Interrupt circular shunt physiology
4. Provide reliable pulmonary blood flow via a systemic-to-pulmonary shunt
5. Decompress the right-sided chambers

Typical components include:

• Patch closure of the tricuspid orifice, usually with fenestration
• Atrial septectomy
• Main pulmonary artery interruption/division when needed
• Systemic-to-pulmonary artery shunt
• Optional right atrial reduction [3,6] (PubMed)

Why the fenestration matters

Fenestration of the tricuspid patch is important because it permits controlled egress of residual RV/coronary venous return and avoids the problem of a blind, pressurized excluded RV chamber. This is a physiologic safeguard, not a minor technical detail [3]. (PubMed)

9. From single-ventricle palliation to staged biventricular thinking

One of the major conceptual shifts in the modern literature is that Starnes palliation is no longer always viewed as a definitive commitment to the Glenn-Fontan pathway. Instead, in selected patients, it may serve as a bridge to later reassessment and even delayed cone reconstruction with biventricular or 1.5-ventricle conversion [3,10]. (PubMed)

This staged philosophy is supported by several strands of evidence:

• Neonatal consensus documents increasingly advocate individualized strategy selection based on morphology, hemodynamics, and institutional expertise rather than one universal pathway [3].
• Selected centers have reported acceptable results with primary neonatal biventricular repair when RV function and valve substrate are favorable [5,6,9].
• Commentary from high-volume congenital programs explicitly frames neonatal Starnes as a paradigm strategy to be followed, in selected cases, by later biventricular repair [10]. (PubMed)

This is probably the most important modern upgrade to the traditional teaching.

10. Neonatal biventricular repair: who may be suitable?

Although the sickest neonates still often require Starnes-type rescue, primary or early biventricular repair is increasingly feasible in selected patients.

Favorable features

• A functional RV with some useful contractile capacity
• Enough leaflet tissue for reconstruction
• Meaningful antegrade RV-PA potential
• Hemodynamics suggesting the RV can be recruited
• Less destructive circular-shunt physiology after stabilization [5,6,9] (PubMed)

Huang and colleagues reported 7 neonates/young infants with severe Ebstein anomaly treated with tricuspid valvuloplasty based on cone principles, with 6 of 7 survivors (86%) and preserved potential for complete biventricular repair [5]. Sano and colleagues similarly emphasized that the key early question is not whether every neonate needs the same operation, but whether biventricular repair versus RV exclusion is feasible in that specific anatomy and physiology [6]. Mizuno and colleagues further suggested that in severe neonatal TR with pulmonary atresia physiology, a TR jet velocity >3.0 m/s may help identify patients more likely to tolerate biventricular repair [9]. (PubMed)

Thus, neonatal decision-making should be framed around RV recruitability and repairability of the valve, not simply severity labels.

11. Cone repair: the dominant reconstructive strategy beyond the unstable neonate

For older infants, children, and adults with reparable anatomy, cone reconstruction has become the preferred operation.

Principle

Cone repair mobilizes available leaflet tissue circumferentially and reattaches it at the true annulus to create a 360-degree cone of leaflet coaptation. This is fundamentally different from older monocusp or partial-coaptation repairs because it aims for a more anatomic restoration of tricuspid inflow [1,7]. (PubMed)

Why cone repair has changed the field

The modern cone era has shown:

• Marked reduction in TR
• Improved leaflet coaptation
• Better chamber remodeling
• Lower reoperation rates than many historical repair strategies [7,8] (PubMed)

Holst and colleagues reported 235 consecutive cone repairs with 0.4% early mortality, early reoperation in 5.9%, and excellent mid-term durability, establishing cone reconstruction as a highly reproducible modern standard in experienced hands [7]. Phillips and colleagues showed similarly strong early outcomes, with less than 10% complication and reoperation rates and very low mortality, while also suggesting that in stable children with good RV function and no major symptoms, waiting until approximately 4 years of age may reduce early postoperative morbidity [8]. (PubMed)

Long-term remodeling perspective

The more recent pediatric literature suggests that successful cone repair may do more than reduce TR. It can also support:

• Durable annular growth relative to somatic growth
• Low long-term mortality and morbidity
• Progressive left ventricular reverse remodeling after relief of right-sided volume burden [11] (PubMed)

This is important because Ebstein anomaly is a biventricular interaction problem, not purely a right-sided lesion.

12. Imaging and preoperative assessment

A high-quality preoperative assessment should answer a practical surgical question: What circulation is sustainable now, and what circulation may be achievable later?

Key issues to define include:

1. True size and contractility of the functional RV
2. Leaflet quantity, mobility, and tethering
3. Degree of TR
4. Presence of functional pulmonary atresia
5. Whether a PDA is beneficial or harmful
6. Evidence of circular shunt
7. Atrial-level shunt direction and restriction
8. Pulmonary valve competence
9. Arrhythmia substrate / accessory pathways [2,3] (PubMed)

Echocardiography remains the primary tool, especially in neonates. In older children and adults, cardiac MRI adds important information regarding RV size, RV/LV interaction, and remodeling. Modern management relies on integrated anatomic-physiologic assessment, not annular displacement alone [2,3].

13. Practical management logic

Neonate with severe instability

• Stabilize ventilation and systemic output
• Reduce PVR when possible
• Determine whether the PDA is helping or worsening physiology
• Identify functional pulmonary atresia and circular shunt early
• Use Starnes-type palliation when RV output is inadequate and hemodynamic collapse persists [3,4,10] (PubMed)

Neonate/infant with recruitable RV and reparable valve

• Consider biventricular repair
• Preserve atrial decompression when needed
• Add shunt support selectively
• Tailor the operation to RV competence and pulmonary outflow physiology rather than age alone [5,6,9] (PubMed)

Child or adult with chronic TR and progressive remodeling

• Favor cone repair before severe irreversible chamber dilation, progressive RV dysfunction, or advanced arrhythmia burden develop [1,2,7,8] (PubMed)

14. Surgical take-home points

• Ebstein anomaly is a disease of the tricuspid valve, right ventricle, right atrium, and cardiopulmonary interaction, not just a valve displacement lesion [1,2].
• The neonatal problem is dominated by high PVR, severe TR, poor RV forward flow, functional pulmonary atresia, and sometimes circular shunt [3,4].
• The post-infancy problem is dominated by chronic volume overload, chamber enlargement, cyanosis in selected patients, ventricular interdependence, and arrhythmia [1,2].
• The Starnes procedure remains the key rescue operation for the most unstable neonates with nonrecruitable RV physiology [3,4,6].
• Modern care has shifted toward individualized staged management, with increasing recognition that neonatal palliation can sometimes be followed by later biventricular conversion [3,5,10].
• Cone reconstruction is now the dominant reconstructive strategy once the anatomy and physiology permit durable biventricular repair [7,8,11]. (PubMed)

References

[1] Dearani JA, Mora BN, Nelson TJ, Haile DT, O'Leary PW. Ebstein anomaly review: what's now, what's next? Expert Rev Cardiovasc Ther. 2015;13(10):1101-1109.

[2] Ramcharan TKW, Goff DA, Greenleaf CE, Shebani SO, Salazar JD, Corno AF. Ebstein's Anomaly: From Fetus to Adult-Literature Review and Pathway for Patient Care. Pediatr Cardiol. 2022;43(7):1409-1428.

[3] Konstantinov IE, Chai P, Bacha E, Caldarone CA, Da Silva JP, Da Fonseca Da Silva L, Dearani J, Hornberger L, Knott-Craig C, Del Nido P, Qureshi M, Sarris G, Starnes V, Tsang V. The American Association for Thoracic Surgery (AATS) 2024 expert consensus document: Management of neonates and infants with Ebstein anomaly. J Thorac Cardiovasc Surg. 2024;168(2):311-324.

[4] Elzein C, Subramanian S, Ilbawi M. Surgical Management of Neonatal Ebstein's Anomaly Associated With Circular Shunt. World J Pediatr Congenit Heart Surg. 2019;10(1):116-120.

[5] Huang SC, Wu ET, Chen SJ, Huang CH, Shih JC, Chou HW, Chang CI, Chiu IS, Chen YS. Surgical Strategy Toward Biventricular Repair for Severe Ebstein Anomaly in Neonates and Infancy. Ann Thorac Surg. 2017;104(3):917-925.

[6] Sano S, Fujii Y, Kasahara S, Kuroko Y, Tateishi A, Yoshizumi K, Arai S. Repair of Ebstein's anomaly in neonates and small infants: impact of right ventricular exclusion and its indications. Eur J Cardiothorac Surg. 2014;45(3):549-555.

[7] Holst KA, Dearani JA, Said SM, Pike RB, Connolly HM, Cannon BC, Sessions KL, O'Byrne MM, O'Leary PW. Improving Results of Surgery for Ebstein Anomaly: Where Are We After 235 Cone Repairs? Ann Thorac Surg. 2018;105(1):160-168.

[8] Phillips KA, Dearani JA, Wackel PL, Stephens EH, Krishnan P, Weaver AL, Cetta F, Johnson JN, Van Dorn CS. Contemporary Early Postoperative Cone Repair Outcomes for Patients With Ebstein Anomaly. Mayo Clin Proc. 2023;98(2):290-298.

[9] Mizuno M, Hoashi T, Sakaguchi H, Kagisaki K, Kitano M, Kurosaki K, Yoshimatsu J, Shiraishi I, Ichikawa H. Application of Cone Reconstruction for Neonatal Ebstein Anomaly or Tricuspid Valve Dysplasia. Ann Thorac Surg. 2016;101(5):1811-1817.

[10] Konstantinov IE, Dearani J, Knott-Craig C, Da Silva JP, Da Fonseca Da Silva L. Commentary: Neonates with Ebstein anomaly: A paradigm strategy of Starnes procedure to be followed by biventricular repair. J Thorac Cardiovasc Surg. 2024;168(1):e5-e8.

[11] Park I, Jun TG, Yang JH, Kang IS, Huh J, Song J, Lee OJ. Long-Term Outcomes of Modified Cone Reconstruction for Ebstein's Anomaly in Pediatric Patients in a Single Center. Korean Circ J. 2024;54. (PubMed)