Tricuspid atresia is a cyanotic congenital heart defect (blue baby), in which the valve between the right atrium and right ventricle fails to develop. The oxygen-poor blood that returns from the body to the right atrium, must pass through a hole in the middle wall of the heart (atrial septal defect or patent foramen ovale), into the left heart. The oxygen-poor blood mixes with the oxygen-rich blood coming from the lungs; therefore, the blood that pumps from the left heart into the aorta and into the body is not fully saturated (sub-normal oxygen levels).
There are several anatomic variations of tricuspid atresia in which there is usually a hole in the lower middle wall of the heart (ventricular septal defect). If this hole is too large it may produce symptoms of congestive heart failure. On the other hand, if the hole is too small, the baby will become more cyanotic (blue skin) and the right ventricle may be very under-developed. In addition, these babies may have significant obstruction (pulmonary valve stenosis). If the pulmonary stenosis is severe enough, there may not be enough blood going into the lungs to get oxygenated. In these babies, blood can reach the lungs to pick up oxygen as long as a communication between the aorta and pulmonary artery (patent ductus arteriosus) remains open. A medication called prostaglandin can keep this important vessel open while the infant is awaiting surgery.
The main arteries of the heart (aorta and pulmonary artery) may be normally positioned or they may be reversed, a condition called transposition of the great arteries.
The symptoms of tricuspid atresia depend on the presence and size of the atrial septal defect and ventricular septal defect, and the relationship of the great arteries. In addition, a baby may look more blue if there is a small hole accompanied with a significant obstruction inside the heart or at the level of the pulmonary valve (pulmonary valve stenosis).
Most commonly, there is a small ventricular septal defect. In this case, the baby may have a low oxygen level and may look blue. The cyanosis may get worse a few days later when the patent ductus arteriosus starts closing up. These babies can develop symptoms of poor oxygenation, fast breathing, poor feeding and looking extremely cyanotic. The baby may not survive if left untreated.
Occasionally, there are babies with tricuspid atresia with excessive blood flow to the lungs that develop congestive heart failure. Babies may present with only mild cyanosis, fast breathing, fast heart rate, poor feeding, and poor weight gain. They may also develop cold, clammy hands and feet, low blood pressure, paleness, and dusky skin color. Babies presenting with these symptoms are critically ill and require emergency treatment. Once they are stabilized, they are transferred to a surgical center.
Tests and Diagnosis:
Babies with tricuspid atresia are usually blue and may have a heart murmur. Low oxygen levels can be measured by using a pulse oximeter or blood gases. The Chest x-ray and electrocardiogram are often abnormal. The echocardiogram is very useful in diagnosis of tricuspid atresia and the associated heart defects that may be present. This test is also useful in determining the size of the right and left ventricles as well as heart function. The color-Doppler echocardiogram confirms the sizes of the patent ductus arteriosus and of the opening in the middle wall between the right and left atrium (patent foramen ovale). The echocardiogram helps the surgeon to determine which type of surgery is necessary.
Blue babies have excessively low levels of oxygen in their body and a medication called prostaglandin can be given intravenously to keep the patent ductus arteriosus wide open and improve blood flow to the lungs or body.
Children with tricuspid atresia and too little blood flow to the lungs will require surgery to establish a connection between the aorta and pulmonary artery. This type of operation is called modified Blalock-Taussig shunt and involves the placement of a small tube between the two arteries. In addition, they may require enlargement of the atrial septal defect.
Children can be expected to undergo further heart surgeries. Most patients with tricuspid atresia will undergo another surgery between three and eight months of age called a bi-directional Glenn or Norwood stage II. This may also be called a cavo-pulmonary anastomosis in which the superior vena cava is detached from its distal part and connected directly to a pulmonary artery. The Blalock-Taussig shunt is then removed. This surgery allows blood from the upper body to flow directly to the lungs to pick up oxygen and alleviates the workload of the heart.
Between the ages of one and four years, most children with tricuspid atresia will be ready for a Norwood stage III, which is also called a modified Fontan procedure. The surgery involves connection of the inferior vena cava directly to a pulmonary artery by means of a conduit (tube) or anastomosis (connection). That means that the blood returning from the lower part of the body will pass directly to the lungs, thus bypassing the heart and alleviating its workload. This connection results in establishment of a more normal oxygen level. Patients may require closure of a fenestration (hole) by means of interventional cardiac catheterization.
Finally, patients with a more complex type of tricuspid atresia, including those with transposition of the great arteries, may require a different type of surgery. For example, patients with transposition of the great arteries may require re-routing of the blood from the left ventricle into the aorta and the aorta will usually need to be reconstructed. If the problem is too much pulmonary blood flow (in cases of a large ventricular septal defect), blood flow to the lungs will usually need to be limited by a special type of operation that will limit the excessive blood flow to the lungs.
Patients with simple tricuspid atresia usually do well, with unexpected survival of 75% to 95% after surgery. Over two-thirds to three-fourths of the patients are alive 25 years after the surgeries.
All patients with this congenital heart defect will require lifelong follow-up by a cardiologist such as Dr. Villafañe. Long-term risks may include formation of clots, stroke, irregular heartbeats, heart failure, gastrointestinal problems, and formation of collateral vessels. These complications may require medication while others may require a pacemaker, interventional cardiac catheterization, heart surgery, and in exceptionally rare cases, heart transplantation.
The long-term quality of life following surgery is generally good, but there may be limitations to certain types of competitive sports. Women should consult prior to any pregnancy, as there may be risks involved, such as clot formation, stroke, irregular heartbeats, heart failure, and miscarriage. Certain medications used in long-term treatment may affect the fetus. It is recommended for you to consult with Dr. Villafañe and a high-risk obstetrician prior to family planning.
Patients with congenital heart defects such as this one may be at risk of endocarditis. The American Heart Association recommends optimal dental hygiene and semiannual dental appointments.