Ebstein's Anomaly At A Glance

Ebstein's Anomaly (EA) is a rare defect of the right side of the child's heart that develops while the child is in the womb; this is also known as a congenital heart defect. 

There are three heart defects involved in EA[1]:

1. Abnormal tricuspid valve
2. Abnormal small right ventricle  
3. Hole in the atrial septum. 

Abnormal tricuspid valve: The tricuspid valve separates the upper (atrium) and lower (ventricle) chambers or rooms on the right side of the heart. In EA, as the baby grows in the womb, the three flaps on the tricuspid valve become longer than normal and are pushed down into the right ventricle (lower chamber). The abnormal shape and position of the tricuspid valve causes a "leak." This allows blood to flow backwards from the ventricle into the atrium.

Abnormal small right ventricle: Due to the tricuspid valve being pushed down the right ventricle, or lower chamber of the heart, is smaller in EA. The right ventricle is responsible for sending blood to the lungs where it gets oxygen by a process called "gas exchange." There is much less blood in the right ventricle in an EA heart, so not enough blood reaches the lungs for gas exchange. Oxygen is required to give the body's cells energy.

Hole in the atrial septum:  A backward flow of blood through the leaky tricuspid valve keeps a hole, called the foramen ovale, in the wall (septum) between the left and right atria open. Normally this hole closes just after birth as the new baby takes life's first breaths. In EA, atrial septum does not close (this is also known as an atrial septal defect). The hole in the atrial septum allows blood to flow into the left atrium from both the lungs and the right atrium. The result is a mix of oxygen-rich blood from the lungs and oxygen-poor blood from the right side of the heart being pushed to the body from the left ventricle. As a result, the cells of the body do not receive all of the oxygen they need to work properly. 

Figure 1. A summary of the defects in a heart with
Ebstein's Anomaly (EA).[1]

References

1. What is Ebstein's Anomaly. Ebstein Anomaly Website. Published January 2011. Available from: https://www.youtube.com/watch?v=jFn0dyU5wUw. Accessed January 7, 2015.