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Tricuspid atresia is a heart defect where the tricuspid valve does not form properly, blocking blood flow from the atrium to the ventricle. It requires emergency medical attention and is usually treated in three surgical stages. The Fontan procedure can significantly delay the need for a transplant, but long-term survival is estimated to be 15 to 30 years. Children with tricuspid atresia should take low-dose aspirin every day and require antibiotics before dental procedures.
The tricuspid valve sits between the right ventricle and the atrium and opens to allow blood to flow from the atrium into the right ventricle. In tricuspid atresia, this valve does not form properly and usually completely blocks blood flow from the atrium to the ventricle. Tricuspid atresia causes immediate problems in the newborn and requires emergency medical attention.
Because blood cannot reach the right ventricle in tricuspid atresia, it cannot pass to the lungs for oxygenation. This may mean that the right ventricle is also malformed as in the hypoplastic right ventricle. Often there may be a ventricular septal defect and an atrial septal defect, which allows some blood to pass to the pulmonic valve, but this does not supply enough to adequately oxygenate the body.
Tricuspid atresia is usually treated in three surgical stages. It is not a repairable defect, but it can be alleviated with surgery. Alternatively, the parents can opt for the transplant. In general, however, parents opt for surgical alleviation because it has a better survival rate at onset and can significantly delay the need for a transplant. Sometimes it is possible to repair or replace the tricuspid valve, but it is usually not possible in tricuspid atresia due to its complete closure and its effects on the right ventricle.
Shortly after the baby with tricuspid atresia is born, a cardiothoracic surgeon places a small shunt into the heart to allow mixed blood to flow into the pulmonary valve. The Blalock-Taussig shunt will give the baby time to grow before returning to the hospital in about three months for Glenn’s shunt. Completion of Fontan usually occurs three to five years after Glenn’s shunt. At that time, the right side of the heart won’t need to function, as blood returning to the lungs will bypass the heart completely. The heart will just need to pump blood around the body, and while the right ventricle may be abnormal, the left ventricle is usually adequately sized and functioning well.
Babies with right-sided flow defects such as tricuspid atresia and hypoplastic right heart tend to have a slightly better survival rate than those born with left-sided defects. The left ventricle in the normal heart is larger and more muscle-bound than the right ventricle. It is ideal for the situation created by the completion of Fontan. Conversely, those babies who have tiny left ventricles must rely on the weaker right ventricle to pump blood around the body. Although in either case, the heart will eventually begin to fail and require a transplant, the left ventricles tend to survive as the only pumping chambers for a little longer.
In tricuspid atresia or right ventricular hypoplasia, long-term survival of the Fontan has been estimated to be 15 to 30 years before a transplant is needed. More recent studies have suggested longer times. Although children undergo three surgeries when they are still small, they are considered more vital and less risky than a transplant. Also, the availability of donor hearts, particularly for newborns, is minimal.
Fontan results in a peculiar arrangement of the “plumbing” of the heart, but does not usually restrict the child with tricuspid atresia from normal activities. Cardiologists can impose certain prohibitions regarding participation in competitive sports. Children also need to be followed up on an annual basis to make sure the Fontan is adequate.
Children with tricuspid atresia and most other heart flow defects should take low-dose aspirin every day and require antibiotics before dental procedures. In general, however, the child with surgically relieved tricuspid atresia can look forward to many years of health. Continued improvements in transplant technology can lead to much higher life expectancy rates than currently, since transplantation is now ultimately necessary.
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