Morphology
 Carpentier
described five anatomic characteristics of Ebstein’s anomaly that are relevant to the
surgical management of the condition:
- There is displacement of the septal and posterior leaflets of the tricuspid valve toward
the apex of the right ventricle.
- The anterior leaflet is attached to the appropriate level of the tricuspid valve
annulus, however, it is larger than normal and may have multiple chordal attachments of
the ventricular wall
- The segment of the right ventricle from the level of the true tricuspid annulus to the
level of attachment of the septal and posterior leaflets is unusually thin and dysplastic
and is described as "atrialized". The tricuspid annulus and the right atrium are
extremely dilated.
- The cavity of the right ventricle beyond the atrialized portion is reduced in size,
usually lacks an inlet chamber, and has a small trabecular component.
- The infundibulum is often obstructed by the redundant tissue of the anterior leaflet as
well as by the chordal attachments of the anterior leaflet to the infundibulum.
In addition, he described four clinical variants with progressively increasing
severity.
In type A, the volume of the true right ventricle is adequate; in type B,
the volume of the right ventricle is small, and there is a large atrialized portion of the
right ventricle; in type C, the volume of the right ventricle is small, and there
is obstruction of the right ventricular outflow tract; and in type D, there is
almost complete atrialization of the right ventricle with the exception of a small
infundibular component, and the only communication between the atrialized ventricle and
the infundibulum is through the antero-septal commissure of the tricuspid valve.
Associated cardiac anomalies
The most common associated anomaly is an atrial septal defect, which occurs in
about 50% of cases. In symptomatic neonates, survival is dependent on the presence of a patent
arterial duct. As alluded to above, there is a variable degree of right ventricular
outflow tract obstruction. A Wolff-Parkinson-White type of accessory pathway,
often with associated pre-excitation, is present in about 10% of cases. Rarely, an
abnormality of ventriculoarterial connection is associated, including ventricular septal
defect and {S,D,D} or {S,L,L} transposition of the great arteries. |
