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Tricuspid Atresia (TA)
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Tricuspid atresia (TA) is a congenital (present at birth) heart defect that occurs due to abnormal development of the fetal heart during the first 8 weeks of pregnancy. The tricuspid valve, normally located between the right atrium and the right ventricle, does not develop properly during pregnancy.
Normally, oxygen-poor (blue) blood returns to the right atrium from the body, travels to the right ventricle, then is pumped through the pulmonary artery into the lungs where it receives oxygen. Oxygen-rich (red) blood returns to the left atrium from the lungs, passes into the left ventricle, and then is pumped through the aorta out to the body.
In tricuspid atresia, however, the following occurs:
- Improper development of the tricuspid valve prevents oxygen-poor (blue) blood from passing from the right atrium to the right ventricle and on to the lungs as it should.
- The right ventricle is also underdeveloped.
- Openings are also present in the atrial and ventricular walls (atrial and ventricular septal defects), allowing oxygen-poor (blue) blood and oxygen-rich (red) blood to mix with each other.
- A patent ductus arteriosus also allows blood to pass through from the aorta to the pulmonary artery and receive oxygen from the lungs.
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Tricuspid atresia makes up 1 to 2 percent of all cases of congenital heart disease. TA occurs equally in boys and girls.
The heart is forming during the first 8 weeks of fetal development. In TA, during the middle of this development period, the tricuspid valve does not develop properly. Ventricular development is influenced by blood flowing through it, and since no blood is able to pass through the tricuspid valve, the right ventricle remains small.
Some congenital heart defects may have a genetic link, either occurring due to a defect in a gene, a chromosome abnormality, or environmental exposure, causing heart problems to occur more often in certain families. Most of the time, this heart defect occurs sporadically (by chance), with no clear reason for its development.
This heart defect causes children to be cyanotic (blue) since a combination of oxygen-poor (blue) and oxygen-rich (red) blood leaves the heart and goes to the body. Just how much oxygen or how little oxygen will be in the bloodstream depends on a number of factors. Some children will only be mildly cyanotic, while others will not have enough oxygen in the blood to meet the body's needs.
Symptoms are noted shortly after birth. The following are the most common symptoms of tricuspid atresia. However, each child may experience symptoms differently. Symptoms may include:
- blue color of the skin, lips, and nail beds
- rapid breathing
- labored breathing
- rapid heart rate
- cool, clammy skin
The symptoms of TA may resemble other medical conditions or heart problems. Always consult your child's physician for a diagnosis.
A pediatric cardiologist and/or a neonatologist may be involved in your child's care. A pediatric cardiologist specializes in the diagnosis and medical management of congenital heart defects, as well as heart problems that may develop later in childhood. A neonatologist specializes in illnesses affecting newborns, both premature and full-term.
Cyanosis is the major indication that there is a problem with your newborn. Your child's physician may have also heard a heart murmur during a physical examination. A heart murmur is simply a noise caused by the turbulence of blood flowing through the openings that allow the blood to mix.
Other diagnostic tests are needed to help with the diagnosis, and may include the following:
- chest x-ray - a diagnostic test which uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film.
- electrocardiogram (ECG or EKG) - a test that records the electrical activity of the heart, shows abnormal rhythms (arrhythmias or dysrhythmias), and detects heart muscle stress.
- echocardiogram (echo) - a procedure that evaluates the structure and function of the heart by using sound waves recorded on an electronic sensor that produce a moving picture of the heart and heart valves.
- cardiac catheterization - a cardiac catheterization is an invasive procedure that gives very detailed information about the structures inside the heart. Under sedation, a small, thin, flexible tube (catheter) is inserted into a blood vessel in the groin, and guided to the inside of the heart. Blood pressure and oxygen measurements are taken in the four chambers of the heart, as well as the pulmonary artery and aorta. Contrast dye is also injected to more clearly visualize the structures inside the heart.
Specific treatment for TA will be determined by your child's physician based on:
- your child's age, overall health, and medical history
- extent of the disease
- your child's tolerance for specific medications, procedures, or therapies
- expectations for the course of the disease
- your opinion or preference
Your child will most likely be admitted to the intensive care unit (ICU) or special care nursery once symptoms are noted. Initially, your child may be placed on oxygen, and possibly even on a ventilator, to assist his/her breathing. Intravenous (IV) medications may be given to help the heart and lungs function more efficiently.
Other important aspects of initial treatment include the following:
- A cardiac catheterization procedure can be used as a diagnostic procedure, as well as initial treatment procedure for some heart defects. A cardiac catheterization procedure will usually be performed to evaluate the defect(s) and the amount of blood that is mixing.
- As part of the cardiac catheterization, a procedure called a balloon atrial septostomy may be performed to improve mixing oxygen-rich (red) blood and oxygen-poor (blue) blood.
- A special catheter with a balloon in the tip is used to create or enlarge an opening in the atrial septum (wall between the left and right atria).
- The catheter is guided through the foramen ovale (a small opening present in the atrial septum that closes shortly after birth) and into the left atrium.
- The balloon is inflated.
- The catheter is quickly pulled back through the hole, into the right atrium, enlarging the hole, allowing blood to mix between the atria.
- An intravenous (IV) medication called prostaglandin E1 is given to keep the ductus arteriosus from closing.
The ductus arteriosus (the normal connection between the aorta and the pulmonary valve) will likely close if the prostaglandin E1 infusion is stopped. Another pathway for blood to reach the lungs to receive oxygen must be surgically created.
A series of operations are performed in the first two years of life that will re-route blood so that enough oxygen is added to the bloodstream to meet the child's needs.
Each operation is performed under general anesthesia. Types of operations include the following:
- Blalock-Taussig shunt
The first operation creates a pathway for blood to reach the lungs. A connection is made between the first artery that branches off the aorta (called the right subclavian artery) and the right pulmonary artery. Some of the blood traveling through the aorta towards the body will "shunt" through this connection and flow into the pulmonary artery to receive oxygen. However, the child will still have some degree of cyanosis since oxygen-poor (blue) blood from the right atrium and oxygen-rich (red) blood from the left side of the heart mix and flow through the aorta to the body.
- Glenn shunt
A second operation, often performed at about 4 to 12 months of age, replaces the Blalock-Taussig shunt with another connection to the pulmonary artery. In this operation, the Blalock-Taussig shunt is removed, and the superior vena cava (the large vein that brings oxygen-poor blood from the head and arms back to the heart) is connected to the right pulmonary artery. Blood from the head and arms passively flows into the pulmonary artery and proceeds to the lungs to receive oxygen. However, oxygen-poor (blue) blood returning to the heart from the lower body through the inferior vena cava will still mix with oxygen-rich (red) blood in the left heart and travel to the body, so the child will remain mildly cyanotic. This operation helps create some of the connections necessary for the final operation, the Fontan procedure.
- Fontan procedure
This operation is often performed at about 18 to 36 months of age, and allows all the oxygen-poor (blue) blood returning to the heart to flow into the pulmonary artery, greatly improving the oxygenation of the blood. The Glenn shunt, connecting the superior vena cava to the right atrium, is left in place. A second connection is made directing blood from the inferior vena cava to the right pulmonary artery. This connection can be created in slightly different variations, depending on the method your child's surgeon prefers, and what is best for your child.
After surgery, infants will return to the intensive care unit (ICU) to be closely monitored during recovery period.
While your child is in the ICU, special equipment will be used to help him/her recover, and may include the following:
- ventilator - a machine that helps your child breathe while he/she is under anesthesia during the operation. A small, plastic tube is guided into the windpipe and attached to the ventilator, which breathes for your child while he/she is too sleepy to breathe effectively on his/her own. After a tricuspid atresia, children will benefit from remaining on the ventilator overnight or even longer so they can rest.
- intravenous (IV) catheters - small, plastic tubes inserted through the skin into blood vessels to provide IV fluids and important medicines that help your child recover from the operation.
- arterial line - a specialized IV placed in the wrist or other area of the body where a pulse can be felt, that measures blood pressure continuously during surgery and while your child is in the ICU.
- nasogastric (NG) tube - a small, flexible tube that keeps the stomach drained of acid and gas bubbles that may build up during surgery.
- urinary catheter - a small, flexible tube that allows urine to drain out of the bladder and accurately measures how much urine the body makes, which helps determine how well the heart is functioning. After surgery, the heart will be a little weaker than it was before, and, therefore, the body may start to hold onto fluid, causing swelling and puffiness. Diuretics may be given to help the kidneys to remove excess fluid from the body.
- chest tube - a drainage tube may be inserted to keep the chest free of blood that would otherwise accumulate after the incision is closed. Bleeding may occur for several hours, or even a few days after surgery.
- heart monitor - a machine that constantly displays a picture of your child's heart rhythm, and monitors heart rate, arterial blood pressure, and other values.
Your child may need other equipment not mentioned here to provide support while in the ICU, or afterwards. The hospital staff will explain all of the necessary equipment to you.
Your child will be kept as comfortable as possible with several different medications; some which relieve pain, and some which relieve anxiety. The staff will also be asking for your input as to how best to soothe and comfort your child.
After discharged from the ICU, your child will recuperate on another hospital unit for several days before going home. You will learn how to care for your child at home before your child is discharged. Your child may need to take medications for a while, and these will be explained to you. The staff will give you written instructions regarding medications, activity limitations, and follow-up appointments before your child is discharged.
Infants who spent a lot of time on a ventilator, or who were fairly ill while in the ICU, may have trouble feeding initially. These babies may have an oral aversion; they might equate something placed in the mouth, such as a pacifier or bottle, with a less pleasant sensation such as being on the ventilator. Some infants are just tired, and need to build their strength up before they will be able to learn to bottle-feed. Strategies used to help infants with nutrition include the following:
- high-calorie formula or breast milk
Special nutritional supplements may be added to formula or pumped breast milk that increase the number of calories in each ounce, thereby allowing your baby to drink less and still consume enough calories to grow.
- supplemental tube feedings
Feedings given through a small, flexible tube that passes through the nose, down the esophagus, and into the stomach, that can either supplement or take the place of bottle feedings. Infants who can drink part of their bottle, but not all, may be fed the remainder through the feeding tube. Infants who are too tired to bottle feed at all may receive their formula or breast milk through the feeding tube alone.
Pain medications, such as acetaminophen or ibuprofen, may be recommended to keep your child comfortable. Your child's physician will discuss pain control before your child is discharged from the hospital.
If any special treatments are to be given at home, the nursing staff will ensure that you are able to provide them, or a home health agency may assist you.
You may receive additional instructions from your child's physicians and the hospital staff.
Infants will remain cyanotic after the first two operations until the final operation (Fontan procedure) is performed. Your child will likely grow and develop more slowly than the average baby because of the lower amounts of oxygen available for the body's needs. Following the Fontan procedure, when oxygen levels improve, many children will see major improvements in growth and development, and can eventually catch up to normal children.
After each operation, your infant will need to be followed by a pediatric cardiologist who will make adjustments to medications, assist you with feeding problems, measure oxygen levels, and determine when it is time for the next operation.
Consult with your child's physician regarding the specific outlook for your child.
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