Tricuspid atresia is a rare heart defect in which the tricuspid valve is permanently closed during the development of an infant’s heart before birth. This condition rarely occurs in isolation. In other words, infants with tricuspid atresia frequently have other congenital heart defects that will also require surgical treatment. Because these problems can be complex, treatment usually begins within days of birth, to maintain adequate blood flow to the body, and may take several years. The patient will require specialized care for this form of heart defect for life. Even as an adult, he will need to be seen regularly by a cardiologist familiar with congenital heart defects.

The tricuspid valve is located between the upper right chamber (right atrium) and lower right chamber (right ventricle) of the heart. Under normal circumstances, it regulates the flow of oxygen-poor blood from the body between the right atrium and the right ventricle. From the right ventricle, blood is pumped through the pulmonic valve, into the pulmonary artery and to the lungs, where it receives fresh oxygen. In a baby with tricuspid atresia, returning oxygen-poor blood is blocked from reaching the lungs. This situation is incompatible with life, unless there is some way that oxygen-poor blood can reach the lungs and eventually be pumped out to nourish the body. Some infants are born with natural defects that allow this to happen. In other cases, physicians create temporary pathways for blood flow. Without rapid treatment, infants born with tricuspid atresia and no associated heart defects would die due to a lack of oxygen.

The most common symptoms associated with tricuspid atresia are failure to thrive and a bluish tint (cyanosis) in the skin, lips, fingernails and other parts of the body. This indicates a lack of blood flow to the lungs (a condition known as blue baby).

The condition may be diagnosed with several tests, including an electrocardiogram and an echocardiogram with ultrasound imaging. These tests may be performed shortly after birth. They may also identify tricuspid atresia before a child is born, although there is no in-utero treatment for the condition.

Children with tricuspid atresia need long-term medical and surgical treatment to survive. Almost all patients will need to undergo an initial shunt procedure to improve blood flow to the lungs. Subsequently, most patients will need to have the Fontan procedure done. This is a series of open-heart surgeries that are performed at two different stages in the young patient’s life. These surgeries restore a natural blood flow to the lungs by bypassing the right ventricle completely. Although surgery cannot rebuild the right side of the heart, children who have undergone the Fontan procedure are able to perform many normal activities.

Tricuspid atresia is a rare congenital heart defect in which the tricuspid valve is permanently closed or absent during the development of an infant’s heart before birth. The tricuspid valve is located between the upper right chamber (right atrium) and lower right chamber (right ventricle) of the heart. The valve is responsible for the smooth passage of blood from the right atrium to the right ventricle. From the right ventricle, blood is normally pumped through the pulmonic valve, into the pulmonary arteries and to the lungs. The complete closure of the tricuspid valve means that oxygen-poor blood cannot reach the lungs in order to become oxygenated.

This defect almost never occurs in isolation, meaning that children with tricuspid atresia usually have associated heart defects. The heart defects most commonly associated with tricuspid atresia include:

• Ventricular septal defect. A hole in the muscular wall (septum) that separates the lower chambers of the heart, or ventricles. In children with tricuspid atresia, this defect, commonly referred to as a VSD, allows blood from both sides of the heart to mingle.
  
  
• Pulmonary stenosis. This occurs when the pulmonic valve, which rests between the right ventricle and the pulmonary artery, is narrowed or obstructed.
  
  
• Transposition of the great arteries. In this condition, the positions of the pulmonary artery and aorta are switched, meaning that the aorta is connected to the right ventricle and the pulmonary artery is connected to the left ventricle.

The severity of tricuspid atresia depends on the presence of other heart defects. In the very rare case of an isolated tricuspid atresia, there is no blood flow between the right and left sides of heart within a few days of birth. Untreated, the infant would rapidly die due to lack of oxygen. However, a number of associated heart defects, including a VSD, actually serve to keep the infant alive by allowing a passageway for blood to travel between the right and left sides of the heart. These include:

• Patent foramen ovale. The foramen ovale is a hole in the wall of muscle (septum) that normally separates the upper chambers of the heart (atria) before birth. Under normal circumstances, the foramen ovale closes shortly after birth as the infant switches to a normal circulation and the lungs start to function. If the foramen ovale remains open, it is known as a patent foramen ovale. In an infant with tricuspid atresia, a patent foramen ovale allows oxygen-poor blood to pass from the right atrium into the left atrium. From there, the blood passes into the left ventricle and is pumped out to the aorta.
  
  
• Patent ductus arteriosus. The ductus arteriosus is an open blood vessel that normally links the pulmonary artery and the aorta in a fetus, thus allowing fetal blood to bypass the lungs during development. After birth, the ductus arteriosus naturally closes as the infant's lungs begin to function. If, however, the ductus arteriosus remains open, it is known as a patent ductus arteriosus. In an infant with tricuspid atresia, this heart defect allows some blood to travel from the aorta, through the ductus arteriosus and into the pulmonary artery to the lungs. Without this additional heart defect, the blood could not get fresh oxygen from the lungs.

Because of the blockage at the tricuspid valve, patients with tricuspid atresia and a VSD or patent foramen ovale suffer from a total right-to-left shunt. This means that blood from the right side of the heart is shunted from the right to left sides of the heart. As a result, the left ventricle performs all the work for circulation. Physicians call this a single ventricle condition. Also as a result, the right ventricle is frequently underdeveloped, or hypoplastic.

Like all congenital heart defects, the cause of tricuspid atresia is unknown. Recent studies have suggested that genetics may play a role. This does not necessarily mean that a parent born with a defect will definitely pass it along to his or her child. Recent studies have shown that tricuspid atresia is somewhat more common among children born to women with diabetes. Routine ultrasound screening is recommended for these women.

Tricuspid atresia produces symptoms similar to those that occur with other congenital heart defects. Because blood is unable to flow to the lungs properly, the infant is likely to be a blue baby at birth. Associated signs and symptoms of a blue baby include:

The infant may also have an unusually large right atrium, as detected by a chest x-ray.

The treatment of tricuspid atresia depends on the presence of associated heart defects. The immediate concern is establishing adequate flow of oxygen-rich blood to the tissues and organs of the body and relieving symptoms of cyanosis. A number of techniques may be performed within days of birth:

A Blalock-Taussig shunt may be performed to establish a blood flow between the aorta and the pulmonary artery. During this surgery, the physician will create a temporary connection between the aorta and pulmonary artery. This connection will be closed later.

Whether or not a patient requires a Blalock-Taussig shunt and/or a Rashkind atrial septostomy initially, all children born with tricuspid atresia will require the Fontan procedure, which is often performed in two stages during infancy and early childhood. The intent of this procedure is to completely bypass the right ventricle while keeping the oxygen-rich and oxygen-poor blood separated. As a result, symptoms and strain on the heart are relieved.

The first stage of the Fontan procedure is called the bidirectional Glenn shunt or hemi-Fontan procedure and is usually performed at 4 to 10 months of age. This procedure establishes a direct connection between the superior vena cava and the pulmonary artery. This connection allows the oxygen-poor blood from the head and arms to drain directly in to the lungs. If there is a Blalock-Taussig shunt, it will be closed at the time of this procedure.

The second stage of the Fontan procedure is performed between the ages of 2 and 5 years. In the second stage, the inferior vena cava, which carries oxygen-poor blood from the abdomen and legs, is connected directly to the pulmonary arteries. Once completed, the Fontan procedure allows the oxygen-poor blood to bypass the heart completely and passively drain directly into the lungs. The oxygen-rich blood returns normally to the left atrium, where it passes into the left ventricle, out the aorta and to the rest of the body.

Although short-term complications may develop, the long-term prognosis for children is good as long as they remain under careful, lifelong medical management. Patients who have had the Fontan procedure performed can generally perform regular children’s activities at about 65 percent of normal levels because they have only one functioning ventricle. Patients require long-term follow-up care by a cardiologist to monitor for abnormal heart rhythms (arrhythmias), heart failure, fluid retention (edema) and clot formation, although the occurrence of each of these problems is uncommon. In addition, both children and adults with tricuspid atresia are susceptible to life-threatening infections of the heart lining and the heart valves (endocarditis). Therefore, they need to take antibiotics before any dental, medical or surgical procedure. Good dental hygiene can also reduce the risk of endocarditis.

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their docto the following questions related to tricuspid atresia:

1. Does my baby have other heart problems in addition to tricuspid atresia?
   
   
2. Will my child’s heart condition affect any other organs or cause other problems?
   
   
3. What special care does an infant with tricuspid atresia require?
   
   
4. Tricuspid atresia was diagnosed during my pregnancy. Do I need to take any special measures before giving birth? Will this mean that the hospital I give birth to my baby must change?
   
   
5. Can medications help my baby’s heart defect instead of surgery?
   
   
6. Should I be alert to any symptoms that may indicate the condition is worsening?
   
   
7. If I have one child with tricuspid atresia, will my future children have it?
   
   
8. What changes will I notice in my baby after the Fontan procedure?
   
   
9. My child had surgery for tricuspid atresia as an infant. Why does he need medicine before dental appointments now?
   
   
10. How long does treatment with prostaglandin work? Is it preferred to septostomy?