Ebstein's anomaly is characterised by downward displacement of the tricuspid 
valve into the right ventricle. The most deformed leaflets are the septal and 
mural ones. The abnormally situated tricuspid orifice produces a portion of the 
right ventricle lying between the atrioventricular ring and the origin of the 
valve. This proximal segment is atrialized. Commonly associated anatomical 
defects include a atrial septal second defect, a ventricular septal defect, 
pulmonary stenosis or atresia, and mitral valve prolapse. An accessory 
conduction pathway (Wolf-Parkinson White syndrome) was found in this 
malformation. It is thought that this malformation is due to a direct 
teratogenic effect of lithium on the atrioventricular junction. Ebstein's 
anomaly can be accurately identified by echocardiography and angiography.