What is tricuspid atresia?
Tricuspid atresia occurs when the tricuspid valve fails to develop while the baby is in the womb. This problem is quite rare, affecting 1 in 15,000 births, and it 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). In babies born with tricuspid atresia, the tricuspid valve is absent (1) and the right ventricle is small (2). In about 25% of babies, the position of the great arteries is also reversed. In some babies, there is also a severe narrowing at the pulmonary valve (3), or there can be complete absence of the pulmonary valve. In all babies with tricuspid atresia, there is no direct pathway for blue blood returning from the body to get to the lungs to pick up oxygen. This is not a problem before the baby is born since oxygen is provided by the mother but after birth the baby’s oxygen levels are lower than normal so the baby’s lips and fingernails look blue or cyanotic. Cyanosis is the medical term used when the lips or nailbeds look blue from too little oxygen in the blood.
In a baby with tricuspid atresia, after birth, the blood must take an indirect pathway to reach the lungs. Most of the time, this pathway is through two holes in the heart. There is usually a hole between the upper chambers called an atrial septal defect (ASD) (4) and a hole between the lower two chambers of the heart called a ventricular septal defect (VSD) (5). Blue blood returning from the body to the heart’s right atrium flows across the ASD to the left upper chamber, through the mitral valve to the left lower chamber and then flows out the aorta to the body, as well as, across the VSD and out the pulmonary valve to the lungs.
If there is severe narrowing at the pulmonary valve, the only way blood can reach the lungs is through a patent ductus arteriosus (6). This a small blood vessel that, prior to birth, permits the blood to by-pass the baby’s fluid-filled lungs. Normally, one to two days after birth, this vessel closes. In a baby with tricuspid atresia with severe pulmonary narrowing, closure of the ductus arteriosus removes the baby’s means of getting blood to the lungs and can result in very low oxygen levels. In this case a medicine called prostaglandin is given to keep the ductus arteriosus from closing.
What are the effects of this defect on my child's health?
Like most heart defects, tricuspid atresia does not have an adverse effect until after the baby is born. It is a serious problem and without surgery, most children would not be able to survive the first year of life.
Before surgery, the health effects in infants include low blood oxygen, congestive heart failure, and/can slow growth. Most babies with tricuspid atresia have very low blood oxygen levels but this can vary depending on the presence of pulmonary narrowing and whether or not the great arteries are reversed. In some babies with tricuspid atresia there is too much blood flow to the lungs causing congestive heart failure and the associated symptoms of poor feeding, clammy sweating, fast breathing, low energy, and slow growth.
Children with tricuspid atresia will need 2 or 3 open-heart operations during childhood. If, after birth, the blood oxygen levels are very low, an aortopulmonary shunt is done, usually during the first one to two weeks of life. Between 6 to 12 months of age a hemi-Fontan operation is done and between 18 and 30 months of age a Fontan operation is done.
Please refer to each operation below to learn more about what to expect health-wise, for a child after each of these operations.
How is this defect diagnosed?
Prenatal diagnosis: Tricuspid atresia can be diagnosed before birth by a fetal echocardiogram or heart ultrasound as early as 18 weeks into the pregnancy. This test is done when there is a family history of congenital heart disease or when a question is raised during a routine prenatal ultrasound.
Symptoms: In a newborn baby, usually, cyanosis is what alerts parents or health care providers that the child may have a heart problem. This is most often noted during the first week of life. Later on, possible symptoms include rapid breathing, sweating, low energy and poor weight gain. If the baby depends on the ductus arteriosus for blood supply to the lungs, it may close during the first week of life causing sudden and profound cyanosis.
Physical findings: Most babies with tricuspid atresia are born at term and are a normal weight and length (since before birth the baby’s oxygen comes from the mother). After birth, the baby’s lips and fingernails may look blue. A heart murmur is almost always heard and congestive heart failure may develop. Symptoms of congestive heart failure in infants include rapid breathing, clammy sweating, poor feeding, and poor growth.
Medical tests: The suspected diagnosis is confirmed by an echocardiogram. Sometimes, a heart catheterization is needed to help the doctors plan the surgery. 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?
Tricuspid atresia is a serious heart problem requires two or three heart operations during the first three years of life. In these babies, the right side of the heart is unable to pump blood. So, the goal of the operations is to bypass the heart’s right side by redirecting blue blood, returning from the body, directly to the lungs via the pulmonary arteries. Experience has shown that the outcomes for children are much better if this type of repair is done one step at a time.
In addition, prior to operations, a heart catheterization may be needed. During this test, soft, thin plastic catheters (tubes) are placed in the large blood vessels in the leg and threaded carefully to the heart. The catheters are used to take pressure measurements inside the heart and to inject contrast or dye so pictures of the heart can be taken.
Systemic-pulmonary artery shunt (also called Blalock-Taussig shunt): This operation is needed in most babies born with tricuspid atresia during the first week or two of life. The goal is to provide a stable supply of blood to the lungs and it is needed when the oxygen levels are too low soon after birth or if the baby is dependent on a patent ductus arteriosus. The surgery involves sewing a Gortex tube between the subclavian artery and the right pulmonary artery (1). Through this tube, a fixed amount of blood reaches the lungs with each heartbeat.
Pulmonary artery band: In babies with tricuspid atresia and transposition of the great arteries without pulmonary stenosis, the problem is too much blood flow to the lungs. In this case, the oxygen levels may be normal but congestive heart failure may develop. Therefore, an operation called a pulmonary artery band may be done. In this operation, a band is placed around the pulmonary artery and tightened just enough to decrease blood flow through this area.
After these operations, the left-heart pumps a mixture of red and blue blood out to the body. It pumps blue blood coming back from the body and red blood coming back from the lungs. Since mixed blood is going out to the body, the oxygen level in the blood is lower than normal. This makes the baby’s lips look a little "dusky" or blue and is more noticeable when the baby cries. Since the baby’s body is used to a lower oxygen level, it does not hurt the child to cry even he/she looks more "blue".
Most babies go home ten days to two weeks after the operation is done. They often go home on three or four heart medicines. Some babies need to use a feeding tube for part of their feedings, at least for the first several weeks. Babies with heart problems often need extra calories in their milk. Breast milk is very good for children with heart problems as it is for all babies. Mothers of babies with heart defects can breast feed and breast milk can be given in the tube feedings. Supplements can be added to the breast milk if the baby needs more calories.
Parents learn about their baby’s care before discharge from the hospital. They will be able to feed their baby and give the medicines that will be needed at home. In this way, parents come to know that they can care for their baby’s special needs. Many parents choose to have a nurse visit their home after the baby leaves the hospital. The nurse can answer questions, assess how the baby is doing, and help parents learn more about their baby’s care.
During the first months of life, most babies grow well and learn to smile, roll over, and play with their toys like other babies. Some babies have trouble gaining weight and need richer milk to drink. Some are slow to learn motor skills. Babies who are slow to develop often benefit from special help that can be arranged through the local school district among other places.
Hemi-Fontan (sometimes called bidirectional Glenn procedure): The goal of this operation is reduce the work of the heart’s only effective pumping chamber, the left ventricle, which up to this point has been doing double-duty, pumping blood to the body and to the lungs. This operation cannot be done right after birth since newborn babies have high pressure in their pulmonary arteries that does not go down until about 6 to 8 weeks of age. Prior to surgery, a heart catheterization is often done to make sure, among other things, that the pressure in the pulmonary arteries is low enough to proceed.
In this operation, the superior vena cava (1) is cut and both ends are is sewn into the right pulmonary artery (2). Now blue blood returning from the upper body flows directly to the lungs (bypassing the heart). A patch is placed over the top part of the heart’s right upper chamber (3). This prevents blood from the upper body from entering the heart and blood from the lower body from entering the lungs. It also maintains a connection that is used for the final stage of the repair and greatly simplifies the last operation. If present, the aortopulmonary shunt is also removed (4).
Most children tolerate the hemi-Fontan operation very well and are able to return home about a week after surgery. The child usually looks about as "blue" as before the surgery since the blood returning from the lower body still bypasses the lungs. Children usually go home on several medicines that often can be stopped six to twelve months later.
After this operation, most children grow and develop normally. They are not highly prone to infections than other children and can be involved in all age appropriate activities. There are no activity restrictions for toddlers and no need to stop children from being too active. Children know when they have reached their limit and will stop and rest. In general, children can return to daycare two weeks after discharge from the hospital.
Fontan procedure: The Fontan procedure is the final operation done to repair tricuspid atresia. The patch placed over the heart’s right atrium (during the hemi-Fontan operation) is removed and a Gortex baffle is sewn in the right atrium. This creates a tunnel that guides blue blood returning from the lower body through the right atrium to the pulmonary artery. After this operation, most of the blue blood goes to the lungs so the child usually looks "pink".
Sometime a small hole, called a fenestration (2), is made in the baffle. This provides a pop-off valve or escape route for blood in case the pressure in the lungs is a little high right after the operation. If the hole does not close on its own, it may be closed at a later time during a heart catheterization. Over time, different methods have been used to close the hole. In the past, a suture was loosely sewn around the hole during the Fontan procedure and used later to pull the hole closed.. A newer method of closing the hole is using a closure device (1). In this method, the device is collapsed within a catheter so that it can be delivered to the site of the fenestration. After the catheter tip is moved into place, the device is pushed out of the catheter, across the fenestration, and secured in place. The child usually stays in the hospital for one night after this procedure.
What are the long-term health issues for children with tricuspid atresia?
After the operations, most children live quite normal lives and most have normal intelligence. They are able to go to daycare, school, play with friends, and participate in the usual recreational activities. They tend to have lower endurance levels than others their age and may require more rests during physical activities. These children are restricted from vigorous and competitive sports so it is important for parents to help them find other areas of interest.
Children with tricuspid atresia are at increased risk for subacute bacterial endocarditis (SBE). This 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 and or abnormalities of the valves. It 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. SBE can usually be prevented by taking an antibiotic before these procedures.
Possible long-term medical problems for children born with tricuspid atresia include abnormal heart rhythms, specifically, atrial flutter and/or sick sinus syndrome and congestive heart failure.
Exercise guidelines: An individual exercise program is best planned with the doctor so that all factors can be included. Children with tricuspid atresia are usually 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. The 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
Dick M, Rosenthal A. The clinical profile of tricuspid atresia. In Rao PS, ed. Tricuspid atresia. Mount Kisco NY: Futura, 1982;83-111.
Driscoll D. Tricuspid atresia. In Garson A, Bricker JT, Fisher D & Neish S, eds. The Science and Practice of Pediatric Cardiology, Vol II, Philadelphia PA: Williams & Wilkins: Baltimore, MD. 1998; 1579-1587.
Goldberg CS, Schwartz EM, Brunberg JA et al. Neurodevelopmental outcome of patients after the Fontan operation: A comparison between children with hypoplastic left heart syndrome and other functional single ventricle lesions. J Pediatr 2000; 137:646-652.
Uzark K, Lincoln A, Lamberti JJ et al. Neurodevelopmental outcomes in children with Fontan repair of functional single ventricle. Pediatrics 1998; 101: 630-633.
Written: S. LeRoy
Reviewed September, 2012