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KEY POINTS
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Key Points

  • Ebstein anomaly is a malformation of the tricuspid valve, causing tricuspid insufficiency and atrialization of a significant portion of the right ventricle.

  • When it progresses it can be associated with right ventricular outflow tract obstruction and arrhythmias.

  • It is rarely associated with extracardiac malformations or fetal aneuploidy.

  • Prognosis for prenatally diagnosed cases is much worse than for those diagnosed later in childhood, with less than 50% of cases surviving to 5 years of age.

  • Pregnancy management rarely needs to be altered significantly, other than to arrange for prompt referral for postnatal cardiac evaluation and likely surgical repair, either by means of valve repair or replacement.

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CONDITION
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Congenital downward displacement of the septal and posterior leaflets of the tricuspid valve is known as Ebstein anomaly. This downward displacement is associated with valvular dysplasia, resulting in tricuspid insufficiency (Schiebler et al., 1968). The displaced septal and posterior leaflets become adherent to the right ventricular walls, which may also be dysplastic. This results in division of the right ventricle into two segments, a proximal atrialized portion that forms a common enlarged chamber with the right atrium and a distal functional right ventricular chamber (Attenhoffer Jost et al., 2007). Significant right atrial enlargement is common, and atrial septal defects or patent foramen ovale is commonly seen during neonatal life (Attenhoffer Jost et al., 2007). Other cardiac malformations coexist with Ebstein anomaly in approximately one-third of cases (Celermajer et al., 1994). The most common additional malformations are pulmonary stenosis, pulmonary atresia with intact ventricular septum, ventricular septal defect, mitral-valve prolapse, aortic coarctation, patent ductus arteriosus, and right ventricular hypoplasia. Rarer coexisting malformations include tetralogy of Fallot, atrioventricular septal defect, aortic atresia, mitral dysplasia, and left ventricular diverticulum (Celermajer et al., 1994).

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INCIDENCE
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The incidence of Ebstein anomaly in the general population is approximately 1 in 10,000 livebirths (Hoffman and Kaplan, 2002). It accounts for 0.3% to 0.6% of congenital heart defects in children and occurs equally in males and females (Rao, 1990).

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First trimester maternal lithium ingestion has been implicated in the occurrence of Ebstein anomaly for more than 20 years. Based on data from an international registry of mothers exposed to lithium during pregnancy it was suggested that the risk of Ebstein anomaly was 400 times greater in lithium-exposed infants than in the general population (Weinstein, 1976). From the registry of 225 infants born to women treated with lithium during the first trimester, there was an 8% incidence of all cardiac malformations and a 2.7% incidence specifically of Ebstein anomaly.

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Subsequent controlled studies have suggested that the actual risk of Ebstein anomaly is considerably less than originally estimated from population registries. A total of two cohort studies and four case–control studies did not demonstrate as high a ...

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