[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Embryology](https://durgical.com/en/embryology/) › [Teratology and prenatal diagnosis](https://durgical.com/en/embryology/#a-teratology) › Lithium and Ebstein anomaly [Embryology](https://durgical.com/en/embryology/) · [Teratology and prenatal diagnosis](https://durgical.com/en/embryology/#a-teratology) # Lithium and Ebstein anomaly - Teratogen Lithium, used for bipolar disorder, is linked to heart defects, mainly of the tricuspid valve; the risk is real but small. Updated 2026-11-01 **See it in 3D:** [Tricuspid septal leaflet](https://durgical.com/en/anatomy/septal-leaflet-of-right-atrioventricular-valve/) · [Tricuspid posterior leaflet](https://durgical.com/en/anatomy/inferior-leaflet-of-right-atrioventricular-valve/) · [Tricuspid anterior leaflet](https://durgical.com/en/anatomy/superior-leaflet-of-right-atrioventricular-valve/) · [Right atrium](https://durgical.com/en/anatomy/right-atrium/) · [Right ventricle](https://durgical.com/en/anatomy/right-ventricle/) ## Key points - First trimester: congenital heart defects, mainly Ebstein anomaly; the absolute risk is small. - Ebstein: the septal and posterior tricuspid leaflets fail to separate from the myocardium and are displaced toward the apex. - Result: a small, 'atrialized' right ventricle, tricuspid regurgitation and a large right atrium. - Late pregnancy: neonatal toxicity (hypotonia, cyanosis), nephrogenic diabetes insipidus and hypothyroidism or goitre. - Fetal echocardiography after first-trimester exposure. ## What it is First-trimester lithium exposure is linked to congenital heart defects, especially Ebstein anomaly, in which the tricuspid valve forms displaced toward the apex of the right ventricle. Recent studies show the risk is smaller than once thought. Because a bipolar relapse is also dangerous, treatment is planned with the psychiatry and obstetric team. ## Key facts - Ebstein anomaly often comes with an atrial septal defect or patent foramen ovale. - It is the congenital heart defect most associated with Wolff-Parkinson-White syndrome. - Lithium's teratogenic mechanism is unclear; interference with developmental signalling pathways has been proposed. - The anterior leaflet is usually large and 'sail-like'. - Large recent studies confirmed the link with a smaller effect than estimated in the 1970s. ## Critical period and mechanism - Critical period: first trimester, while the heart and its valves form. - The tricuspid leaflets form by 'peeling off' (delaminating) from the right ventricular wall. - In Ebstein anomaly delamination fails for the septal and posterior leaflets, which stay stuck and displaced downward. - Lithium's mechanism: unclear; effects on signalling pathways such as Wnt have been proposed. ## Prevention - Preconception planning with psychiatry and obstetrics to balance fetal risk and relapse risk. - Medicines in pregnancy are decided with the treating professional; they are not stopped on one's own. - Fetal echocardiography and monitoring of the exposed newborn. ## What it does to the embryo and fetus - Ebstein anomaly and other congenital heart defects. - Newborn: cyanosis, cardiomegaly from a large right atrium, arrhythmias (accessory pathways). - Late exposure: floppy, lethargic infant; nephrogenic diabetes insipidus; goitre and hypothyroidism. - Polyhydramnios from fetal polyuria. ## In the lab - Fetal echocardiography: tricuspid valve displaced toward the apex and tricuspid regurgitation. - Postnatal ECG: pre-excitation when an accessory pathway is present. ## Memory aid Lithium 'sinks the tricuspid': the leaflets never peel off and slide down toward the right ventricular apex. ## Test yourself Think of the answer, then tap the question to see it. ## Which heart defect is classically linked to first-trimester lithium? Ebstein anomaly. ## What is the embryological error in Ebstein anomaly? The septal and posterior tricuspid leaflets fail to delaminate from the right ventricular wall and are displaced toward the apex. ## What effects can lithium have on a newborn exposed late in pregnancy? Hypotonia and lethargy, nephrogenic diabetes insipidus and hypothyroidism or goitre. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/embryology/lithium-and-ebstein-anomaly/) ## See it in 3D The structures of Durgical's 3D anatomy where it is found. - [Tricuspid septal leaflet](https://durgical.com/en/anatomy/septal-leaflet-of-right-atrioventricular-valve/) - [Tricuspid posterior leaflet](https://durgical.com/en/anatomy/inferior-leaflet-of-right-atrioventricular-valve/) - [Tricuspid anterior leaflet](https://durgical.com/en/anatomy/superior-leaflet-of-right-atrioventricular-valve/) - [Right atrium](https://durgical.com/en/anatomy/right-atrium/) - [Right ventricle](https://durgical.com/en/anatomy/right-ventricle/) ## Related - [Ebstein anomaly](https://durgical.com/en/embryology/ebstein-anomaly/) - [Heart tube: formation and looping](https://durgical.com/en/embryology/heart-tube-formation-and-looping/) - [Ventricular septation and the endocardial cushions](https://durgical.com/en/embryology/ventricular-septation-and-the-endocardial-cushions/) - [Atrial septation: septum primum, septum secundum and foramen ovale](https://durgical.com/en/embryology/atrial-septation-septum-primum-septum-secundum-and-foramen-ovale/) - [Principles of teratology: critical periods, dose and genotype](https://durgical.com/en/embryology/principles-of-teratology-critical-periods-dose-and-genotype/) ## Related conditions - [Bipolar disorder](https://durgical.com/en/conditions/bipolar-disorder/) - [Wolff-Parkinson-White syndrome](https://durgical.com/en/conditions/wolff-parkinson-white-syndrome/) - [Diabetes insipidus (central and nephrogenic)](https://durgical.com/en/conditions/diabetes-insipidus/) - [Goitre](https://durgical.com/en/conditions/goitre/) - [Hypothyroidism](https://durgical.com/en/conditions/hypothyroidism/) [← All of embryology](https://durgical.com/en/embryology/) 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: [Ebstein Anomaly and Malformation](https://www.ncbi.nlm.nih.gov/books/NBK534824/) (StatPearls Publishing (NCBI Bookshelf), 2023); Langman's Medical Embryology, 13th ed., ch. 9: Birth Defects and Prenatal Diagnosis (Wolters Kluwer, 2015). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/embryology/lithium-and-ebstein-anomaly/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/embryology/lithium-and-ebstein-anomaly/