Ebstein's anomaly is a malformation of the tricuspid valve and right ventricle. The classic description is something along the lines of: a tethered and displaced septal (and posterior) leaflet, a "sail-like" anterior leaflet, and a variable "atrialized" portion of the right ventricle. Echocardiographically, it is important to understand the measurable parameters that help describe the spectrum of disease, and thus help guide the management.
At one end of the spectrum is a tricuspid valve that is apically displaced just slightly more than normal:
Tricuspid Valve Offset Calculator:
At the other end of the spectrum are the critically ill neonates whose biventricular circulation— and very survival— are not certain:
Great Ormond Street Ebstein Index Calculator:
Ultimately, it is the actual leaflet and right ventricle morphology which dictates just how much and what kind of repair can be attempted, and 3D echo seems best suited to describing these.
Source: Ebstein's Anomaly
Attenhofer Jost et al. Circulation.2007; 115: 277-285