Embryology · Heart and vessels
Ebstein anomaly !
- Malformation
The tricuspid valve is set too far toward the tip of the heart: the right atrium grows and the right ventricle stays small.
Updated 2026-11-01
See it in 3D: Tricuspid septal leaflet · Tricuspid posterior leaflet · Tricuspid anterior leaflet · Right atrium · Right ventricle · Interatrial septum
What it is
In Ebstein anomaly the septal and posterior tricuspid leaflets fail to peel away from the right ventricular wall and attach lower than normal. Part of the ventricle becomes 'atrialized', the valve leaks and the right atrium dilates. It can be cyanotic if an ASD or patent foramen ovale is present, and it is associated with lithium and Wolff-Parkinson-White syndrome.
Embryological cause
- Weeks 5–8: tricuspid leaflets form as myocardium beneath the cushion tissue is hollowed out (delaminates).
- In Ebstein anomaly this hollowing fails for the septal and posterior leaflets, which stay stuck to the wall.
- The valve's functional hinge is displaced toward the apex.
- The ventricular portion above the leaflets behaves like atrium (atrialized).
Markers
- Lithium (prenatal exposure)
- Accessory pathways (WPW)
How it presents
- Wide spectrum: from neonatal cyanosis and heart failure to an incidental adult finding.
- Cyanosis from right-to-left flow across the foramen ovale or an ASD.
- Palpitations and tachycardias from accessory pathways (WPW).
- Tricuspid regurgitation murmur; hepatomegaly in severe cases.
Diagnosis
- Prenatal or postnatal echocardiography: apical displacement of the septal leaflet and a huge right atrium.
- ECG: pre-excitation (delta wave) in WPW; right bundle branch block.
- Chest X-ray: a very large, box-shaped heart.
Test yourself
Think of the answer, then tap the question to see it.
What is the embryological cause of Ebstein anomaly?
Failed delamination of the septal and posterior tricuspid leaflets, which stay attached to the wall and displaced toward the apex.
Which drug is classically associated with Ebstein anomaly?
Lithium in the first trimester.
Which rhythm disorder is associated with Ebstein anomaly?
Wolff-Parkinson-White syndrome, from accessory pathways.
See it in 3D
The structures of Durgical's 3D anatomy where it is found.
- Tricuspid septal leaflet
- Tricuspid posterior leaflet
- Tricuspid anterior leaflet
- Right atrium
- Right ventricle
- Interatrial septum
Related
- Ventricular septation and the endocardial cushions
- Lithium and Ebstein anomaly
- Atrial septal defect and patent foramen ovale
- Principles of teratology: critical periods, dose and genotype
Related conditions
Educational content on embryonic development; not a guide to prenatal diagnosis or to medicines in pregnancy and no substitute for a health professional's advice. No doses are given.
Sources: Langman's Medical Embryology, 13th ed., ch. 13: Cardiovascular System (Wolters Kluwer, 2015); Ebstein anomaly: MedlinePlus Medical Encyclopedia (National Library of Medicine (MedlinePlus), 2026).
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Representative model, for educational purposes only.