Ebstein anomaly is a type of congenital heart disease characterized by the abnormal development of the tricuspid valve and the right ventricle. Depending on the severity of these abnormalities, the symptoms experienced by those born with Ebstein anomaly can vary tremendously.
Some infants with this condition are critically ill at birth. Others with Ebstein anomaly live into adulthood without any symptoms at all. However, almost everyone born with this condition will develop cardiac problems sooner or later.
What Is Ebstein Anomaly?
Primarily, Ebstein anomaly is caused by a failure of the tricuspid valve to develop normally in the fetus. The leaflets of the tricuspid valve do not move into their normal position, at the junction of the right atrium and the right ventricle, during development. Instead, the leaflets are displaced downward, within the right ventricle. Further, the leaflets themselves are often laminated (“stuck”) to the wall of the right ventricle, and thus do not open and close appropriately.
Because the tricuspid valve in Ebstein anomaly is displaced downward, the portion of the right ventricle that is located above the abnormal tricuspid valve is “atrialized.” That is, the atrial chamber of the heart will contain not only the normal atrial tissue but also part of the right ventricular tissue.
Because of the abnormal positioning and the distortion of the tricuspid valve that occurs in Ebstein anomaly, the valve is usually “leaky.” As a result, tricuspid regurgitation is typically the chief manifestation of this condition.
In addition, the atrialization of the portion of the right ventricle that lies above the displaced tricuspid valve also causes problems. The atrialized portion of the right ventricle beats when the rest of the right ventricle beats, and not when the right atrium beats. This discordant muscular action within the atrial chamber exaggerates the tricuspid regurgitation and also creates a tendency for the blood within the right atrium to stagnate—a condition that may produce blood clots.
The severity of Ebstein anomaly is related to the degree of the displacement and malformation of the tricuspid valve, and the amount of right ventricular tissue that is subsequently atrialized. People born with Ebstein anomaly who have relatively few (or no) symptoms usually have very little valvular displacement.
People born with Ebstein anomaly also have a high incidence of having other congenital heart problems. These include patent foramen ovale, atrial septal defect, pulmonary outflow obstruction, patent ductus arteriosus, ventricular septal defect, and extra electrical pathways in the heart that can produce cardiac arrhythmias. If one or more of these other congenital problems are present, the symptoms and the outcomes of people with Ebstein anomaly are often substantially worsened.
Ebstein anomaly occurs in about 1 of 20,000 live births. While certain genetic mutations have been associated with Ebstein anomaly, no particular mutation is thought to be a major cause of this condition. An association between Ebstein anomaly and the pregnant mother’s use of lithium or benzodiazepines has been reported, but no causal association has been proven. For the most part, Ebstein anomaly appears to occur randomly.
The symptoms experienced by people with Ebstein anomaly vary tremendously, depending both on the degree of the tricuspid valve abnormality and on the presence or absence of other congenital heart problems.
Children born with severe tricuspid valve dysfunction caused by Ebstein anomaly often have other congenital heart problems as well, and may be critically ill from birth. These babies often have severe cyanosis (low blood oxygen levels), dyspnea, weakness, and edema (swelling).
Children born with Ebstein anomaly who have significant tricuspid regurgitation, but no other serious congenital heart problems, may be healthy babies but will often develop right-sided heart failure either during childhood or adulthood.
On the other hand, if the tricuspid valve dysfunction is only mild, a person with Ebstein anomaly can remain without symptoms their whole lives.
There is a strong association between Ebstein anomaly and anomalous electrical pathways in the heart. These so-called “accessory pathways” create an abnormal electrical connection between one of the atria and one of the ventricles; in Ebstein anomaly, they almost invariably connect the right atrium with the right ventricle.
These accessory pathways often cause a type of supraventricular tachycardia called atrioventricular reentrant tachycardia (AVRT). Sometimes these same accessory pathways can cause Wolff Parkinson White syndrome, which can lead not only to AVRT, but also to far more dangerous arrhythmias, including ventricular fibrillation. As a result, these accessory pathways can create an increased risk for sudden death.
Because Ebstein anomaly often produces sluggish blood flow within the right atrium, blood clots tend to form there. If these blood clots embolize (that is, break off), they can travel through the circulation and cause tissue damage. So Ebstein anomaly is associated with an increased incidence of pulmonary embolus, and (because clots from the right atrium can move through a patent foramen ovale into the left atrium), they can also cause a stroke.
The major causes of death from Ebstein anomaly are heart failure and sudden death.
The key test in diagnosing Ebstein anomaly is the echocardiogram—usually, a transesophageal echo test gives the most accurate results. With an echocardiogram, the presence and the degree of a tricuspid valve abnormality can be accurately assessed, and most other congenital cardiac defects that may be present can also be detected.
In adults and older children who are receiving their initial evaluation for Ebstein anomaly, exercise testing is usually done to assess their exercise capacity, the blood oxygenation during exercise, and the response of their heart rate and blood pressure to exercise. These measurements are helpful in judging the overall severity of their cardiac condition, and the necessity and the urgency of surgical treatment.
It is also important to evaluate people who have Ebstein anomaly for the presence of cardiac arrhythmias. In addition to annual electrocardiograms (ECG) and ambulatory ECG monitoring, most of these people should be evaluated by a cardiac electrophysiologist once they are diagnosed, to assess their likelihood of developing potentially dangerous arrhythmias.
In general, if Ebstein anomaly is producing significant symptoms, the treatment is surgical repair.
Surgery in newborns with severe Ebstein anomaly is usually delayed as long as possible, because of the high risk of repairing this problem in infants. These babies are usually managed with aggressive medical support in an intensive care unit, in the attempt to delay surgery until they have a chance to grow. Whenever possible, surgery is delayed for at least several months.
In older children and adults newly diagnosed with Ebstein anomaly, surgical repair is strongly recommended as soon as any symptoms develop. However, if they have a significant degree of heart failure, an attempt is made to stabilize them with medical therapy before operating.
The surgical procedures used for Ebstein anomaly can be quite complicated, and the specific surgical interventions that are performed vary from person to person, depending on the state of the tricuspid valve, on the presence or absence of additional congenital heart defects, on whether or not severe heart failure is present, and on the patient’s age.
In general, the goal of surgery is to normalize (as much as possible) the position and the function of the tricuspid valve, and to reduce the atrialization of the right ventricle. In milder cases this goal can be approached using techniques to surgically repair and reposition the tricuspid valve. In more severe cases, tricuspid valve replacement with an artificial valve is necessary. Surgery for Ebstein anomaly also incorporates the repair of atrial and/or ventricular septal defects if present, and any of the other congenital heart problems that are diagnosed.
Children and adults who are diagnosed with only mild Ebstein anomaly, and who do not have any symptoms, often do not require surgical repair at all. However, they still need careful monitoring for the rest of their lives for any change in their cardiac condition. Furthermore, despite their “mild” Ebstein anomaly, they still may have accessory electrical pathways and therefore a risk of cardiac arrhythmias, including an increased risk of sudden death. So a careful evaluation should be done to check for this risk. If a potentially dangerous accessory pathway is identified, ablation therapy should be strongly considered to get rid of the abnormal electrical connection.
The prognosis of Ebstein anomaly depends on the severity of the tricuspid valve problem, and on the presence or absence of other congenital heart problems. In babies with this condition who are born critically ill, the risk of mortality is high—over 30 percent die before they can be discharged from the hospital.
The risk of early death when Ebstein anomaly is diagnosed in later childhood or adulthood also depends on the severity of the condition. However, in recent decades, aggressive surgical management, and the prophylactic treatment of potential cardiac arrhythmias, have greatly improved the prognosis of people with Ebstein anomaly.
A Word From Tips For Healthy Living
Ebstein anomaly is a congenital malformation and malpositioning of the tricuspid valve. The significance of this condition varies from person to person, and ranges from being extremely severe to relatively mild. It is important for anyone with Ebstein anomaly, even those with the very mild forms, to receive a full cardiac evaluation and lifelong monitoring. With modern surgical techniques and careful management, the prognosis of people with Ebstein anomaly has improved substantially in recent decades.