Pulmonary Atresia (PA)
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Pulmonary atresia (PA) is a complicated congenital (present at birth) defect that occurs due to abnormal development of the fetal heart during the first eight weeks of pregnancy.
The pulmonary valve is found between the right ventricle and the pulmonary artery. It has three leaflets that function like a one-way door, allowing blood to flow forward into the pulmonary artery, but not backward into the right ventricle.
With pulmonary atresia, problems with valve development prevent the leaflets from opening; therefore, blood cannot flow forward from the right ventricle to the lungs. Before birth, while the fetus is developing, this actually is not a threat to life, because the placenta provides oxygen for the baby and the lungs are not functional. Blood entering the right side of the fetal heart passes through an opening called the foramen ovale that allows oxygen-rich (red) blood to pass through to the left side of the heart and proceed to the body.
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In some cases, there may be a second opening, this time in the ventricular wall, that allows blood in the right ventricle a way out. This opening is called a ventricular septal defect (VSD). If there is no VSD, the right ventricle receives little blood flow before birth and does not develop fully.
After birth, the placenta no longer provides oxygen for the newborn—the lungs must provide it. However, with no pulmonary valve opening present, blood must find another route to reach the lungs and receive oxygen.
The foramen ovale normally shuts at birth, but may stay open in this situation, allowing oxygen-poor (blue) blood to pass from the right atrium to the left atrium. From there, it goes to the left ventricle, out the aorta, to the body. This situation cannot support life, since oxygen-poor (blue) blood cannot meet the body's demands. Newborns also have a connection between the aorta and the pulmonary artery, called the ductus arteriosus, that allows some of the oxygen-poor (blue) blood to pass into the lungs. Unfortunately, this ductus arteriosus normally closes within a few hours or days after birth.
Because of the low amount of oxygen provided to the body, pulmonary atresia is a heart problem that is labeled "blue-baby syndrome."
The problem occurs as the heart is forming during the first eight weeks of fetal development.
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.
Symptoms will be noted shortly after birth. The obvious indication of PA is a newborn who becomes cyanotic (blue) in the transitional first day of life when the maternal source of oxygen (from the placenta) is removed. The degree of cyanosis is related to the presence of other defects that allow blood to mix, including a patent (open) ductus arteriosus.
The following are the most common symptoms of pulmonary atresia. However, each child may experience symptoms differently. Symptoms may include:
- Rapid breathing
- Difficulty breathing
- Pale, cool, or clammy skin
The symptoms of pulmonary atresia 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 a 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.
Diagnostic testing for congenital heart disease varies by the child's age, clinical condition, and institutional preferences. Some tests that may be recommended include the following:
- Chest X-ray. A diagnostic test which uses invisible X-ray 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 pulmonary atresia 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 or her breathing. Intravenous 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), whether the foramen ovale or ductus arteriosus are still open, and the amount of blood that is mixing.
- As part of the cardiac catheterization, a procedure called balloon atrial septostomy may be performed to improve mixing of oxygen-rich (red) blood and oxygen-poor (blue) blood between the right and left atria.
- A special catheter with a balloon in the tip is used to create 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, and a hole is created, allowing blood to mix between the atria.
- An intravenous medication called prostaglandin E1 is given to keep the ductus arteriosus from closing.
These interventions will allow time for your baby to stabilize.
- Surgical repair. Ultimately, surgery is necessary to improve blood flow to the lungs on a permanent basis. The exact type of surgery needed depends on a number of factors including the size of the right ventricle and whether there is a communication between the right and left ventricles (a ventricular septal defect or VSD). If there is a VSD, then the operation may involve closure of the VSD and placement of a homograft conduit from the right ventricle to the pulmonary artery (which is an artery and a valve from another human being). This allows blood to leave the right ventricle through this conduit (homograft) into the lungs. If there is no VSD, then a series of three operations are usually recommended and performed shortly after birth. In this series of operations, blood flow is redirected to the lungs and the body with various surgical connections. The first operation is placement of a Blalock-Taussig shunt (or BT shunt) that allows blood to flow to the lungs after the patent ductus arteriosus closes. The second operation is a Glenn procedure, where the superior vena cava is connected directly to the right lung artery. The third and final operation is a Fontan procedure, where the inferior vena cava is connected to the right lung artery.
After surgery, infants will return to the ICU to be closely monitored during recovery.
While your child is in the ICU, special equipment will be used to help him or her recover, and may include the following:
- Ventilator. A machine that helps your child breathe while he or 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 or she is too sleepy to breathe effectively on his or her own. After a pulmonary 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 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 of which relieve pain, and some of which relieve anxiety. The staff will also be asking for your input as to how best to soothe and comfort your child.
After discharge from the ICU, your child will recuperate on another hospital unit 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 properly.
- 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.
The outlook varies from child to child. Follow-up care at a center offering pediatric congenital cardiac care should be carried out regularly. It is not unexpected for multiple re-operations to be performed to replace conduits or revise a palliation.
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.
There is significant risk for progressive development of complications such as heart failure, dysrhythmias, and protein-losing enteropathy (liver congestion).
Pregnancy and other non-cardiac surgeries pose major risks and require careful evaluation and discussion with a congenital cardiologist.
Regular follow-up care at a center offering pediatric or adult congenital cardiac care should continue throughout the individual's lifespan.
Consult your child's physician regarding the specific outlook for your child.
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