Fetal Ebstein Anomaly

Ebstein anomaly is an anomay in which the tricuspid valve is displaced downward into the right ventricle. This may be associated with significant atrealisation of the right ventricle, leading to significant reduction in the right ventricular capacitance, potentially resulting in functional RV hypoplasia. These infants have typically an enlarge right atrium, and a potential right to left shunting at the atrial level (postnatally) with significant tricuspid insufficiency. They are at risk of arrhytmia (such as re-entry tachycardia). 

Severe Ebstein can be associated with circular shunt physiology, in which the blood flow enter the Pulmonary Artery via the ductus arteriosus, following which it returns to the RV by significant pulmonary insufficiency. The blood flow then enters the right atrium secondary to tricuspid valve insufficiency and to the left atrium via the patent foramen ovale. Following which, it enters the left ventricle (LV) and is pumped into the aorta, to eventually re-enter the ductus arteriosus. This physiology leads to a low cardiac output state and may compromise organ oxygenation.

Circular shunt physiology in Ebstein: Aorta → Ductus → Pulmonary artery → Pulmonary Insufficiency → Right Ventricle → Tricuspid insufficiency → Right atrium → Foramen Ovale → Left atrium → Mitral valve → Left ventricle → Aortic valve → Aorta → Ductus arteriosus (Learn more here, and here). Some have described the use of maternal NSAIDs as a way to constrict the fetal duct in an attempt to address this fatal physiology for the fetus / newborn. Article here on "Surgical Management of Neonatal Ebstein’s Anomaly Associated With Circular Shunt".

Case by Dr Wadi Mawad - Pediatric Cardiology at the Montreal Children's Hospital