Ebstein anomaly is a rare heart defect that’s present at birth (congenital). In this condition, your tricuspid valve is in the wrong position and the valve’s flaps (leaflets) are the incorrect shape. As a result, the valve does not work properly. Blood might leak back through the valve, making your heart work less efficiently.
https://www.mayoclinic.org/diseases-conditions/ebsteins-anomaly/symptoms-causes/syc-20352127

