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Ebstein anomoly radiology

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Ebstein anomaly radiology chest X-ray echocardiography

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Here is a comprehensive radiology overview of Ebstein Anomaly:

Ebstein Anomaly — Radiology

Anatomy (Pathological Basis)

Ebstein anomaly is a congenital tricuspid valve and right ventricular (RV) malformation with six key components:
  1. Failure of delamination (adherence of tricuspid leaflets to underlying myocardium)
  2. Apical/anterior displacement of the functional tricuspid annulus
  3. Dilation of the "atrialized" RV with variable wall thinning
  4. Redundant, fenestrated, sail-like anterior leaflet
  5. Dilation of the true tricuspid annulus (right AV junction)
  6. Variable RV myocardial dysfunction
Diagram of Ebstein anomaly showing apically displaced tricuspid orifice, massively enlarged RA, and small functional RV
Diagram: The tricuspid orifice is displaced apically into the RV. The true annulus level is at the AV groove, leaving a large "atrialized" RV between them. — Braunwald's Heart Disease

Plain Chest Radiograph (CXR)

The CXR is often the first imaging modality and has classic findings:
FeatureDescription
Massive cardiomegalyMarkedly elevated cardiothoracic ratio (often ≥0.65)
"Box-shaped" / globular heartCharacteristic silhouette; smooth, rounded borders
Prominent right heart borderDue to massive right atrial (RA) enlargement
Decreased pulmonary vascularityOligemic lung fields (reduced pulmonary blood flow)
Small aortic knobLow cardiac output, reduced systemic flow
Small pulmonary trunk shadowCompared to the giant cardiac silhouette
AP CXR showing massive cardiomegaly with globular "box-shaped" heart, prominent right heart border, and oligemic lung fields in Ebstein anomaly
AP CXR: Massive cardiomegaly with rounded right heart border (RA enlargement), oligemic lungs, and small aortic knuckle — classic Ebstein.
A cardiothoracic ratio ≥0.65 is a prognostic marker for decreased survival in unrepaired cases.

Echocardiography (Primary Diagnostic Tool)

Echocardiography is the cornerstone of diagnosis and assessment:
  • Apical displacement of the septal tricuspid leaflet >8 mm/m² from the AV junction (or >20 mm absolute in adults) — diagnostic criterion
  • The inferior and occasionally anterior leaflets may also be displaced
  • The anterior leaflet is elongated, "sail-like," and may be fenestrated or tethered
  • Atrialized RV: the basal portion of the RV between the true AV groove and the displaced valve orifice behaves hemodynamically as part of the RA
  • Tricuspid regurgitation: typically severe and eccentric
  • ASD/PFO: present in the majority; direction of shunting (right-to-left = cyanosis) must be assessed with color Doppler
  • TEE may be needed to fully characterize anterior leaflet distal tethering
Key echocardiographic imaging goals (Grainger & Allison's Diagnostic Radiology):
  • Describe apical displacement of septal leaflet
  • Assess mobility of anterosuperior and inferior leaflets
  • Note eccentric coaptation
  • Quantify tricuspid regurgitation
  • Quantify RA dilation and size of atrialized RV
  • Assess RV and LV volume, function, and mass
  • Exclude RVOT obstruction

Cardiac MRI (CMR)

CMR is increasingly used for comprehensive functional assessment, especially pre-operatively:
  • Quantifies degree of tricuspid valve displacement and rotation
  • Measures RV volumes and systolic function (RVEF) — RV dysfunction predicts mortality and sustained VT
  • Quantifies tricuspid regurgitation severity
  • Assesses LV volumes (may be small due to interventricular septal shift)
  • Calculates Qp:Qs ratio for atrial-level shunt quantification
  • Detects LV non-compaction (an associated finding)

CT

CT is less commonly used but can characterize:
  • Enlargement of the tricuspid annulus (see axial CT below)
  • Overall cardiac chamber dimensions
  • Associated anomalies (RVOT, pulmonary arteries)
Multi-panel: ECG showing RBBB, CXR with right heart enlargement, and CT showing enlarged tricuspid annulus (arrow) in Ebstein anomaly
Panel B: CXR with right heart border enlargement (CTR ~0.5). Panel C: Axial CT — arrow points to enlarged tricuspid annulus. Panel A: ECG with RBBB pattern.

Associated Radiological/Imaging Findings

ModalityFinding
ECGTall/peaked "Himalayan" P waves, prolonged PR, RBBB, delta waves (WPW), atrial flutter/fibrillation
CXRBox-shaped cardiomegaly, oligemia, small aorta
EchoDisplaced septal leaflet, TR, atrialized RV, ASD
CMRRV dysfunction, quantify TR, Qp:Qs
AllASD/PFO, accessory pathways, pulmonary stenosis, VSD

Key Numbers

  • Diagnostic threshold: septal leaflet displacement >8 mm/m² (or >20 mm in adults)
  • Incidence: 1 per 200,000 live births
  • Poor prognosis markers on imaging: cardiothoracic ratio ≥0.65, RV/LV systolic dysfunction, severe TR
— Braunwald's Heart Disease, Grainger & Allison's Diagnostic Radiology
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