EA: The Diagnosis

EA: How it is Diagnosed?

Ebstein's Anomaly (EA) can be diagnosed by the healthcare provider in the prenatal period, before birth, or in the postnatal period, following birth. The method of diagnosing EA is different in each of these periods. Regardless of what period EA is detected in, it is useful to know the severity in order to plan treatment.

Diagnosis in the Prenatal Period

During the second or third trimester of pregnancy, a health care provider will view the fetus' heart by ultrasound. This will reveal information related to the size, shape and general condition of the baby's heart. If the healthcare provider has concerns, an echocardiogram often with a color doppler to visualize the blood flow will be ordered. Click here to see an echocardiogram with color doppler of a 20 week fetus with EA heart. The right atrium will appear enlarged with the tricuspid valve pushed down into the right ventricle and a great amount of backward blood flow through the tricuspid valve with each heart beat. It is very important to identify EA in the prenatal period because without surgical treatment there is an 85% mortality rate in early infancy. [1]

Diagnosis in the Postnatal Period

The above video shows a Magnetic Resonance Imaging (MRI) view of the heart. This is a useful imaging technique and the technique preferred for diagnosing EA in the postnatal period (childhood and adulthood). An MRI of the heart offers a comprehensive view of the motion of the heart walls, blood flow through the heart, and function of the heart valves. Often an MRI is ordered along with a color doppler echocardiogram following an abnormal ECG. Additional heart stress tests may also be performed. In these tests, the patient exercises and the movement of blood between the right atrium and left atrium through the atrial septal defect increases causing the patient's performance at exercise to decrease due to lack of oxygen to the body. [1]

References
1.  Galea J, Ellul S, Schembri A, et al. Ebstein Anomaly: A Review. Neonat Network.  September 2014: 33(5): 268-274.

EA: What to Look For

EA: The Signs and Symptoms
Ebstein's Anomaly (EA) is usually identified before or just after birth, but can be identified in childhood, adolescence, or adulthood depending on how severe the tricuspid abnormality is. The signs and symptoms of EA vary depending on the age of the individual. 

Before Birth: EA can be detected before birth during routine ultrasounds. The backward flow of blood through the tricuspid valve can lead to symptoms of heart failure, incomplete lung development, or an enlarged heart.[1]

Newborn: A blue tone to the skin (cyanosis) in newborns indicates a low supply of oxygen in the blood and is a common sign of EA in newborns. When the blood pressure rises, such as when the newborn cries, the cyanosis may become more noticeable. Additional signs are abnormal heart beats (arrythmias), enlargement of the right side of the heart.[1]

Figure 1. A newborn with blue skin around the mouth (cyanosis)
which indicates a low oxygen supply in the blood. [2]

Infancy and Adolescence: In infancy and adolescence the symptoms of EA include cough, fatigue, shortness of breath, rapid and shallow breathing with great effort, fast heartbeat, and failure to thrive (difficulty gaining weight and growing appropriately). These symptoms are usually caused by failure of the right side of the heart to pump enough blood to the lungs and failure of the left side of the heart to pump enough blood to the body. The severity of these symptoms depends on how displaced the tricuspid valve is.[1]

Figure 2. The child at the left suffers from failure to thrive,
while the child at the right is a normal weight child of the
same age. The energy children expend to get enough oxygen
in the blood while suffering from EA can lead to the wasted
appearance of the child on the left. [3]

Adulthood: In adult patients EA may be detected by an abnormal electrocardiogram (ECG). Abnormal heart rythyms on the ECG are due to the stress of EA making the right side of the heart bigger than normal. The most common type of irregular rhythm of the heart in a patient with EA is supraventricular tachycardia (SVT), where the heartbeat is abnormally fast and prevents the lower chambers from completely filling with blood, decreasing the amount of blood that is pushed to the body. They may also show signs of atrial enlargement on the ECG.[1}

Figure 3. An ECG showing supraventricular tachycardia,
a rhythm common in adults with EA. [4]

References:

1. Galea J, Ellul S, Schembri A, et al. Ebstein Anomaly: A Review. Neonat Network.  September 2014: 33(5): 268-274.
2. Perioral Cyanosis. Stanford School of Medicine Web site. Available from: http://newborns.stanford.edu/PhotoGallery/PerioralCyanosis1.html. Accessed January 23, 2015.
3. Failure to Thrive. Mr. Doctor Web site. Available from: http://mrdoctor.org/failure-to-thrive-in-infants-and-children/ Accessed January 23, 2015.
4. Supraventricular Tachycardia (SVT). Still image from YouTube Web site. Available from; https://www.youtube.com/watch?v=zLzJUOa54fc. Accessed January 23, 2015.

EA: But, what is it exactly?

A NORMAL HEART:

Before we discuss how the heart develops incorrectly in Ebstein's Anomaly (EA), we need to understand how the heart normally functions in a newborn and child.

Before birth, a hole called the ductus arteriosis, is present between the upper rooms of the heart so that blood can flow through the heart without getting to the lungs. After a baby is born and using their lungs, that hole closes to form a wall called the atrial septum which separates the right and left sides.  

Oxygen-poor blood from the body flows from the right atrium through the tricuspid valve (a door which prevents the blood from flowing backwards) to the right ventricle. From the right ventricle, the heart squeezes blood into the lungs so that it can get oxygen. Then the oxygen rich blood flows back into the left side of the heart at the left atrium where it passes to the left ventricle, and is eventually squeezed out of the heart and carried to all the cells of the body. The cells of the body need oxygen in order to function properly. 

Click here to watch how blood flows through a normal heart.

Figure 1. A normal heart. The tricuspid valve

closes properly, preventing blood from flowing

backwards into the right atrium, and the

atrial septum is fully formed. [1]

A HEART WITH EBSTEIN'S ANOMALY:

 Ebstein's Anomaly (EA) is a 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. 

In EA, the door that separates the right atrium and right ventricle, the tricuspid valve, is pushed downward.[2]

As a result, the right atrium is much larger than normal and the the right ventricle much smaller than normal. This results in less blood flowing to the lungs to get oxygen. Tricuspid valve door also does not close properly, and the oxygen poor blood is allowed to flow backwards into the right atrium.[2] 

The backward flow of blood keeps the hole (ductus arteriosis) in the wall between the left and right atria open, so the atrial septum does not fully form (this is also known as an atrial septal defect),  to allow blood to flow into the left atrium from both the lungs and the right atrium.[2]

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. The child may have a characteristic blue appearance to the skin, known as cyanosis, due to a lack of oxygen to the cells of the body. 

Click here to watch blood flow through the heart in EA. 

Figure 2. This is a heart with EA. The tricuspid valve 

is pushed into the left atrium and the atrial septal 

defect is shown. Blood can flow backwards

 from the left ventricle and into the left atrium 

through the tricuspid valve and hole between the 

right and left atria. [1]

What Causes EA?

Although the exact causes of EA are not well understood, EA has been linked to the following [2,3]:

• Inherited genetic defects.
• Infants born to women over the age of 35.
• Marijuana use during pregnancy.
• Exposure to "organic solvents" (paint, varnish, cleaning agents) during pregnancy.
• Use of lithium during pregnancy.

Lithium is considered the major factor in development of EA in newborns. Lithium is commonly used to treat bipolar mania and other manic disorders. Lithium is very toxic when not used properly and these toxic effects can be transferred to the fetus if the woman uses Lithium during pregnancy. If a woman is pregnant or planning to become pregnant and taking Lithium to treat mania, she should discuss the safety of Lithium in pregnancy and other treatment options with her health care provider. 

References:

1. Ebstein's Anomaly. The Mayo Clinic Web site. Available from: http://www.mayoclinic.org/diseases-conditions/ebsteins-anomaly/multimedia/ebsteins-anomaly/img-20007245. Accessed January 21, 2015. 
2. Osiro S, Tiwari KJ, Mathenge N, et al. When Lithium Hurts: A Look at Ebstein Anomaly. Cardio in Rev.           October 2013: 21(2): 257-263. doi: 10.1097/CRD.0b013e318280c966
3. Galea J, Ellul S, Schembri A, et al. Ebstein Anomaly: A Review. Neonat Network.  September 2014: 33(5): 268-274. 

How Common is EA?

EA: How Common Is it?

Ebstein's Anomaly (EA) is a very rare heart condition which affects the tricuspid valve separating the upper and lower chambers on the right side of the heart. EA occurs in less than one newborn out of 200,000.[2]

More than half of all EA cases are first identified by an ultrasound of the mother's pelvic region before birth.

Of the cases detected before birth, 3 out of 10 of the infants will not survive the first year and 5 out of 10 will not survive until the age of 30. If EA is detected after birth, meaning there are no signs of EA until childhood or during the teenage years, survival rates are much better; more than 8 out of 10 of these individuals live into their 30s.[3]

Due the low occurrence of EA in the population and other heart conditions that also occur in people with EA, the exact number of individuals with EA is difficult to assess. The Centers for Disease Control and Prevention (CDC) often includes EA in the category of "critical congenital heart defects." The CDC includes EA in the list of important congenital heart defects that the medical team checks for in newborn ultrasound screenings. These screenings are usually done in the first 24 hours of the baby's life, before they are sent home from the hospital. The true number of individuals born with Ebstein's Anomaly each year in the United States needs to be further studied.

What other medical problems might be present in a child with EA?
EA often does not occur alone. Most individuals with EA have other heart problems, too. Other diseases that also be present in infants or children with EA are:

• Pulmonary atresia - This occurs when the valve that lets blood flow from the right ventricle to the lungs (pulmonic valve) does not form correctly. No blood is allowed to enter the lungs from the heart to get oxygen and the cells of the body, which depend on oxygen, suffer. This defect requires surgery.[4]
• Coarctation of the aorta - The aorta, a large vessel that carries oxygen-rich blood to the body, is narrowed in coartation of the aorta. So the heart has to pump much harder to get enough oxygen-rich blood to the body. [5]
• Ventricular septal defect - A hole in the wall that separates the lower chambers of the right and left sides of the heart (the ventricle). This causes some of the oxygen-rich blood to be pumped back into the lungs, rather than being pumped to the body's cells through the aorta.[6] 
• Tetralogy of Fallot - A rare condition caused by four heart defects which affect the structure of the heart. The result, like EA, is that oxygen-poor blood reaches the cells of the body. Children with this condition usually have blue-tingled skin. [7]
• Atrioventricular septal defect - Holes in the walls separating the upper chambers of the heart (atria) and lower chambers of the heart (ventricles). This results in extra blood flowing to the lungs and overwork of the heart. Eventually the heart may enlarge. [8]
• Mitral valve prolapse - The mitral valve separates the upper and lower left chambers of the heart. In mitral valve prolapse the flaps of the valve bulge upward into the left upper chamber as the heart contracts so oxygen-rich blood sometimes leaks backwards from the left ventricle to the left atrium. [9]

Figure 2. An ultrasound image of a heart with Ebstein's Anomaly (EA). This
image shows the displacement of the tricuspid valve (TV) into the right ventricle
 (RV). the right atrium (RA) is bigger than normal. This is how a baby's heart
would appear on an ultrasound when diagnosed with EA. [10]

References

2. Osiro S, Tiwari KJ, Mathenge N, et al. When Lithium Hurts: A Look at Ebstein Anomaly. Cardio in Rev. 

          October 2013: 21(2): 257-263. doi: 10.1097/CRD.0b013e318280c966

3. Lupo PJ, Langlois PH, Mitchell LE. Epidemiology of Ebstein Anomaly: Prevalence and patterns in Texas, 1999-2005.            Am J Med Gen Pt A. May 2011: 155(5): 1007-1014. doi: 10.1002/ajmg.a.33883
4. Pulmonary atresia. The Mayo Clinic Web site. Availabe from: http://www.mayoclinic.org/diseases-conditions/pulmonary-atresia/basics/definition/con-20030896. Accessed January 15, 2015. 
5.Coarctation of the aorta. The Mayo Clinic Web site. Available from: http://www.mayoclinic.org/diseases-conditions/coarctation-of-the-aorta/basics/definition/con-20031772. Accessed January 15, 2015.
6. Ventricular septal defect. The Mayo Clinic Web site. Availabe from: http://www.mayoclinic.org/diseases-conditions/ventricular-septal-defect/basics/definition/con-20024118. Accessed January 15 ,2015. 
7. Tetraology of Fallot. The Mayo Clinic Web site. Available from: http://www.mayoclinic.org/diseases-conditions/tetralogy-of-fallot/basics/definition/con-20043262. Accessed January 15, 2015. 
8. Atrioventricular Canal Defect. The Mayo Clinic Web site: http://www.mayoclinic.org/diseases-conditions/atrioventricular-canal-defect/basics/definition/con-20024932. Accessed January 15, 2015.
9. Mitral Valve Prolapse. The Mayo Clinic Web site. Available from: http://www.mayoclinic.org/diseases-conditions/mitral-valve-prolapse/basics/definition/con-20024748. Accessed January 15, 2015.
10. Ultrasound of Ebstein's Anomaly. The Ultrasound of Life Web site. Available from: http://www.fetalultrasound.com/online/text/7-070.HTM. Accessed January 15, 2015.

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.