What Is Ebstein's Anomaly?

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Ebstein's anomaly (sometimes referred to as Ebstein anomaly) is a congenital heart disease in which the tricuspid valve and the right ventricle do not develop normally. As a result, the valve does not function as it should to keep blood flowing in the right direction, allowing it to leak back from the lower to the upper chambers on the right side of the heart.

Symptoms of Ebstein's anomaly depend on the severity of the abnormality and so can range from virtually no symptoms at all to low blood oxygen levels, dyspnea (difficulty breathing), and, weakness. In extreme cases, the condition can be fatal. Imaging tests of the heart are used to diagnose and assess the extent of Ebstein's anomaly. People who have symptoms typically must undergo corrective surgery.

An Uncommon Condition

Ebstein's anomaly occurs in about 1 of 20,000 live births, accounting for 1% of all birth defects.

Symptoms of Ebstein's Anomaly

The symptoms of Ebstein's anomaly vary tremendously, depending on the degree to which the tricuspid valve is malformed. Some babies with this condition die before birth, while others have such mild cases they do not develop symptoms until later in childhood or even adulthood. Ultimately, however, most people with any degree of Ebstein's anomaly develop heart problems sooner or later.

Babies with severe malformation of the tricuspid valve often have co-occuring heart defects and may have severe cyanosis (low blood oxygen levels), a bluish tint to their skin, dyspnea, weakness, and edema (swelling).

Ebstein's anomaly is associated with a high incidence of additional congenital heart problems including:

Children born with Ebstein's anomaly who have significant tricuspid regurgitation but no other severe congenital heart problems, may be healthy babies but will often develop right-sided heart failure during childhood or adulthood.

Adults who have mild Ebstein's anomaly tend to:

  • Have shortness of breath
  • Experience occasional chest pain
  • Get easily winded easily during exercise
  • Have heart rhythm disturbances (arrhythmia)

Complications

There are numerous complications associated with Ebstein's anomaly that require a doctor's care and careful monitoring.

Anomalous Electrical Pathways

There is a strong association between Ebstein's anomaly and anomalous electrical pathways in the heart. These so-called “accessory pathways” create an abnormal electrical connection between one of the atria (the atria are the two upper chambers of the heart) and one of the ventricles; in Ebstein's 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.

Blood Clots

Ebstein's anomaly can slow the flow of blood within the right atrium so much that clots can form and embolize (break off) and then travel through the body and cause tissue damage. For this reason, Ebstein's anomaly is associated with an increased incidence of pulmonary embolus as well as stroke.

The major causes of death from Ebstein's anomaly are heart failure and sudden death from cardiac arrhythmias.

Leaky Valve

Because of the abnormal positioning and distortion of the tricuspid valve that occurs in Ebstein's anomaly, the valve tends to be regurgitant (“leaky").

In addition, the atrialized portion of the right ventricle beats when the rest of the right ventricle beats, but not when the right atrium beats. This discordant muscular action exaggerates the tricuspid regurgitation and also creates a tendency for the blood within the right atrium to stagnate, increasing the risk of clotting.

Enlarged Heart

In Ebstein's anomaly, the tricuspid valve is displaced downward and the atrium contains part of what would normally be the right ventricle as well as normal atrial tissue. These factors make for an oversized right atrium and also cause the right ventricle to enlarge as it works harder to push blood to the lungs. Over time, the enlarged right side of the heart weakens and heart failure may occur.

Causes

Ebstein's anomaly is a congenital birth defect, which means it results because of a mutation in a gene. This mutation causes the tricuspid valve in the heart of a fetus to develop abnormally. Specifically, the leaflets (flaps) that open and close in order to allow for the flow of blood do not move into their normal position at the junction of the right atrium and the right ventricle.

Instead, the leaflets are displaced downward within the right ventricle. Further, the leaflets often adhere to the right ventricle wall, and therefore do not open and close correctly.

Among the mutations that have been associated with Enstein's anomaly are myosin heavy chain 7 and NKX2.5.

There is evidence associating Ebstein's anomaly in some babies with the use of lithium or benzodiazepines by their mothers while pregnant. However, there's been no research showing a direct causal relationship.

Diagnosis

Diagnosing Ebstein's anomaly is a matter of visualizing the heart in order to observe the abnormality. The imaging test used most often is a transesophageal echo test, a type of echocardiogram (echo) in which ultrasound is used to provide images of the heart as it beats.

An echo can accurately assess the presence and the degree of a tricuspid valve abnormality and detect most other congenital cardiac defects that may be present. Magnetic resonance imaging (MRI) may be used to assess the dimensions and functionality of the ventricle.

For adults and older children, a cardiac stress test may be used to assess exercise capacity, blood oxygenation during physical activity, and the response of heart rate and blood pressure to exercise. These measurements help judge the overall severity of their cardiac condition and whether surgery the necessity and the urgency of surgical treatment.

Ongoing evaluation of the progression of Ebstein's anomaly typically requires testing for the presence of cardiac arrhythmias, usually with annual electrocardiograms (ECG) and ambulatory ECG monitoring.

Treatment

Surgery is required to treat symptomatic cases of Ebstein's anomaly. The goal of surgery is to normalize (as much as possible) the position and the function of the tricuspid valve and reduce the atrialization of the right ventricle. Procedures used to treat Ebstein's anomaly include:

  • Repair or repositioning the tricuspid valve
  • Atrial septal defect repair: Many people with Ebstein’s anomaly have a hole in the septum (the tissue between the heart’s upper chambers [the atria]). This hole will be surgically closed along with the valve repair.
  • Arrhythmia surgery (maze procedure): Maze surgery may be recommended in combination with valve surgery. During maze surgery, new electrical pathways in the heart are created to reestablish a normal heart rhythm.
  • Heart transplant: This may be necessary when the valve is seriously deformed, heart function is poor, and other treatments are not effective.

Surgery for newborns with severe Ebstein's anomaly is usually delayed as long as possible—at least several months. Meanwhile, these babies must be managed with aggressive medical support in a neonatal intensive care unit.

Ideally, older children and adults newly diagnosed with Ebstein's anomaly undergo surgical repair as soon as symptoms develop. However, for those with a significant degree of heart failure, an attempt is made to stabilize them with medical treatment before operating.

Children and adults who are diagnosed with only mild Ebstein's 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 changes in their cardiac condition.

Furthermore, despite their “mild” Ebstein's anomaly, they still may have accessory electrical pathways and therefore are at risk of cardiac arrhythmias, including an increased risk of sudden death. If a potentially dangerous accessory pathway is identified, ablation therapy may be advised.

For this procedure, catheters tipped with electrodes are used to identifyaccessory electrical pathways responsible for arrhythmias and block them using heat, freezing energy, or radiofrequency energy.

A Word From Verywell

Ebstein's anomaly is a rare congenital heart condition. If you or your child has been diagnosed with this condition, it is possible your case or theirs is mild and easy to treat. However, even severe cases of Ebstein's anomaly can be managed and thanks to modern surgical techniques and careful management, the prognosis for people with Ebstein's anomaly has improved substantially in recent decades.

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Article Sources
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