What is Ebstein’s anomaly of the tricuspid valve?
Ebstein’s anomaly occurs when the tricuspid valve fails to develop normally while the baby is in the womb. This problem ranges widely from very mild to severe. It is quite rare affecting 1 in 210,000 births and occurs equally in boys and girls.
In the normal heart, the tricuspid valve is located on the heart’s right side between the atria (the upper chamber) and the ventricle (the lower chamber). A heart valve consists of thin flaps of tissue anchored in a fibrous ring. The valves ensure that the blood flows in a forward direction through the heart, opening to permit blood to flow forward, and closing as the heart contracts to prevent blood from flowing backwards. In Ebstein’s anomaly, the tricuspid valve leaflets (1) are attached below their usual place, down into the area that is usually part of the right ventricle (2). Two problems can result from their abnormal placement: the valve may leak and the small right ventricle may serve as a less effective pumping chamber.
In addition to the valve problem, most people (90%) with Ebstein’s anomaly also have a hole between the heart’s upper two chambers, the atria. This is called an atrial septal defect or ASD (3).
Between 10 and 25% of children with Ebstein’s anomaly also have Wolff-Parkinson-White syndrome. This can cause intermittent episodes of an abnormal fast heart rate called supraventricular tachycardia. In this situation, the child’s heart rate may be 200 to 250 beats per minute.
What are the effects of this defect on my child's health?
The health effects of Ebstein’s anomaly stem from the degree of valve displacement and leakage, the size of the atrial septal defect, and whether Wolff-Parkinson-White syndrome is present. The onset of symptoms is quite variable too, ranging from right after birth to adolescence. In mild Ebstein’s, with only mild displacement of the leaflets and very little valve leakage, the child may never develop heart-related symptoms.
If the valve is severely displaced and leaky, blood cannot move forward effectively and "backs-up" into the right atrium. This causes an increase in right atrial pressure so, in the presence of an ASD, blood will follow the path of least resistance and flow from the right atrium to the left atrium. From there, it flows to the left ventricle and out to the body. This means that blue blood (blood that never went to the lungs to pick up oxygen) flows out to the body. This causes the child’s nailbeds and lips to look blue. The medical term for this is cyanosis. Over time, the valve leakage and poor function of the right ventricle can cause symptoms of heart failure such as low energy levels, poor stamina, rapid breathing, clammy sweating, and low endurance levels.
The pooling of blood in the right atrium can also cause the atria to dilate or enlarge. This can lead to an abnormal fast heart rhythm called atrial flutter. Children with Ebstein’s are also more likely to have another type of abnormal fast heart rhythm called supraventricular tachycardia. This problem may occur whether or not they have Wolff-Parkinson-White syndrome.
How is this defect diagnosed?
Symptoms: The symptoms depend on how severely the valve is affected. In very mild cases, there are usually no heart-related symptoms. If the valve is more severely affected, the child’s lips and nailbeds may look blue and symptoms of congestive heart failure such as low energy, rapid breathing, sweating, poor feeding, irritability, and poor growth may be seen. Episodes of very fast heart rate (supraventricular tachycardia) may also occur. Palpitations or "skipped" beats are common.
Physical findings: Most babies with Ebstein’s anomaly are born at term and are a normal weight and length (since before birth the baby’s oxygen comes from the mother). The blood oxygen levels may be low causing the child’s lips and nailbeds to look blue. A heart murmur is usually heard.
Medical tests: The suspected diagnosis is confirmed by an echocardiogram. An oxygen saturation test is used to measure the blood oxygen levels. Other tests include an electrocardiogram and chest x-ray.
How is the problem treated?
Many children with Ebstein’s anomaly do very well with little or no treatment required. If symptoms of congestive heart failure develop, medications such as digoxin or lasix may be used. In some patients, however, heart surgery is needed. In a newborn, if the valve is very leaky and abnormal, the baby’s blood oxygen may be so low that surgery is needed during the first weeks of life. In this case, a Blalock-Taussig shunt (also called an aortopulmonary shunt) is done. In this operation, a Gortex tube is sewn between the subclavian artery and the right pulmonary artery. This ensures that enough blood will reach the lungs with each heartbeat.
In older children, if the valve is very leaky and there are symptoms of heart failure, surgery to repair or replace the tricuspid valve and close the atrial septal defect may be needed.
Supraventricular tachycardia may be treated with medications or radiofrequency ablation.
What are the long-term health issues for children with Ebstein’s anomaly?
Overall, the outlook for children with Ebstein’s is very good. Children with mild Ebstein’s may never have any symptoms or problems. Continued advancements in surgical and medical therapies have improved outcomes even for those children with the severest form of the defect.
SBE prophylaxis: Children with Ebstein’s anomaly are at increased risk for subacute bacterial endocarditis (SBE). SBE is an infection of the heart caused by bacteria in the blood stream. Children with heart defects are more prone to this problem because of the altered flow of blood through the heart. SBE can occur after dental work or medical procedures on the GI or respiratory tract because these procedures almost always result in some bacteria entering the blood. Fortunately, the problem can usually be prevented by giving an antibiotic before these procedures.
Exercise guidelines: An individual exercise program is best planned with the doctor so that all factors can be included. Children with mild Ebstein’s generally have no exercise restrictions. Those with more severe forms may be restricted from vigorous or competitive sports but can participate in recreational sports. It is important for them to always be able to self-limit their activity, that is, to rest whenever they feel the need to do so. These children can usually participate in gym class but should be allowed to self-limit their level of exertion and they should not be graded (which could increase the pressure to exceed their natural limits).
References
Maclellan-Tobert SG & Porter C. Ebstein’s anomaly of the tricuspid valve. In Garson A, Bricker JT, Fisher D & Neish S, eds. The Science and Practice of Pediatric Cardiology, Vol I, Philadelphia PA: Williams & Wilkins: Baltimore, MD. 1998: 1303-1315.
Written by: S. LeRoy RN, MSN, CPNP
Reviewed January, 2010