Mild forms of Ebstein anomaly may not cause symptoms until later in adulthood. If signs and symptoms are present, they may include:

• Shortness of breath, especially with exertion
• Fatigue
• Heart palpitations or abnormal heart rhythms (arrhythmias)
• A bluish discoloration of the lips and skin caused by low oxygen (cyanosis)

Ebstein anomaly is a heart defect that you have at birth (congenital). Why it occurs is still unknown. To understand how Ebstein anomaly affects your heart, it helps to know a little about how the heart works to supply your body with blood.

How your heart works

Your heart is made up of four chambers. The two upper chambers (atria) receive blood. The two lower chambers (ventricles) pump blood.

Four valves open and close to let blood flow in one direction through the heart. Each valve consists of two or three strong, thin flaps (leaflets) of tissue. When closed, a valve prevents blood from flowing to the next chamber or from returning to the previous chamber.

Oxygen-poor blood returns from your body and flows into the right atrium. Blood then flows through the tricuspid valve and into the right ventricle, which pumps the blood to your lungs to receive oxygen. On the other side of your heart, oxygen-rich blood from your lungs flows into the left atrium, through the mitral valve and into the left ventricle, which then pumps the blood to the rest of your body.

What happens in Ebstein anomaly

In Ebstein anomaly, the tricuspid valve sits lower than normal in the right ventricle. This makes it so that a portion of the right ventricle becomes part of the right atrium (becomes atrialized), causing the right atrium to be larger than usual. Because of this, the right ventricle can't work properly.

Also, the tricuspid valve's leaflets are abnormally formed. This can lead to blood leaking backward into the right atrium (tricuspid valve regurgitation).

The placement of the valve and how poorly it's formed may vary among people. Some people may have a mildly abnormal valve. Others may have a valve that is extremely displaced, and it may leak severely.

The more the tricuspid valve leaks, the more the right atrium enlarges as it receives more blood. At the same time, the right ventricle enlarges (dilates) as it tries to cope with the leaky valve and still deliver blood to the lungs. Thus, the right-sided chambers of the heart enlarge, and as they do, they weaken, which may lead to heart failure.

Other heart conditions associated with Ebstein anomaly

Several other heart conditions may be associated with Ebstein anomaly. A few common conditions include:

• Holes in the heart. Many people with Ebstein anomaly have a hole between the two upper chambers of the heart called an atrial septal defect or a small flap-like opening called a patent foramen ovale (PFO). A PFO is a hole between the upper heart chambers that is present in all babies before birth but usually closes after birth, although it may remain open in some people without causing issues.

These holes may allow oxygen-poor blood in the right atrium to mix with oxygen-rich blood in the left atrium, decreasing the amount of oxygen available in your blood. This causes a bluish discoloration of the lips and skin (cyanosis).

• Abnormal heartbeats (arrhythmias). Some people with Ebstein anomaly have an abnormal heart rhythm (arrhythmia) characterized by rapid heartbeats (tachycardia).

These types of arrhythmias can make your heart work less effectively, especially when the tricuspid valve is leaking severely. In some cases, a very fast heart rhythm may cause fainting spells (syncope).

• Wolff-Parkinson-White (WPW) syndrome. Some people with Ebstein anomaly may also have a condition known as Wolff-Parkinson-White syndrome — an abnormal electrical pathway in the heart. The presence of WPW syndrome can lead to very fast heart rates and fainting spells.

Congenital heart defects, such as Ebstein anomaly, happen early in the development of a baby's heart.

It's uncertain what risk factors might cause the defect. Genetic and environmental factors are both thought to play a role. People with a family history of heart defects may be more likely to have Ebstein anomaly. A mother's exposure to certain medications, such as lithium, may be associated with Ebstein anomaly in the child.

Many people with mild Ebstein anomaly have few complications. However, you may need to take some precautions in certain situations:

• Being active. If you have mild Ebstein anomaly with a nearly normal heart size and no heart rhythm disturbances, you can probably participate in most physical activities.

Depending on your signs and symptoms, your doctor may recommend that you avoid certain competitive sports, such as football or basketball. Your doctor can help you decide which activities are right for you.

• During pregnancy. In many cases, women with mild Ebstein anomaly can safely have children. But pregnancy does have risks.

If you plan on becoming pregnant, be sure to talk to your doctor ahead of time. He or she can tell you if it's safe for you to become pregnant and help decide how much extra monitoring you may need throughout pregnancy and childbirth. He or she may also suggest other treatments for your condition or symptoms before you become pregnant.

Being pregnant puts additional strain on your heart and circulatory system not only during pregnancy, but also during labor and delivery. However, vaginal delivery may be possible. Rarely, severe complications can develop that can cause death to the mother or baby.

Other complications that may result from Ebstein anomaly include heart failure, heart rhythm problems and, less commonly, sudden cardiac arrest or stroke.