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Pulmonary Atresia
source: Children’s Heart Federation
Animation available at: http://www.childrens-heartfed.com/resources__and__info/heart_conditions/pulmonary_atresia
Pulmonary Atresia
What is pulmonary atresia?
Pulmonary atresia (PA) is a complicated congenital (present at birth) defect that
occurs when the pulmonary valve, located between the right ventricle and pulmonary
artery, is not formed properly.
The pulmonary valve 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 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, which allows oxygen-rich (red) blood to pass through to the left side
of the heart and proceed to the body.
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. With no pulmonary valve opening present, however, 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." Pulmonary atresia occurs in
about one out of every 10,000 live births.
What causes pulmonary atresia?
Pulmonary atresia occurs due to the improper development of the heart during the
first eight weeks of fetal growth. 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.
What are the symptoms of pulmonary atresia?
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
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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 ductus
arteriosus.
The following are the most common symptoms of pulmonary atresia. Each child,
however, may experience symptoms differently. Symptoms may include:
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rapid breathing
difficulty breathing
irritability
lethargy
pale, cool or clammy skin
What are the treatments for pulmonary atresia?
Specific treatment for pulmonary atresia will be determined by your child's physician
based on:
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your child's age, overall health and medical history
extent of the disease
your child's tolerance for specific medications, procedures or therapies
how your child's doctor expects the disease will progress
your opinion or preference
Your child most likely will 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 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:
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A cardiac catheterization procedure can be used as a diagnostic procedure, as
well as an 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.
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. Ultimately, surgery is
necessary to improve blood flow to the lungs on a permanent basis. A series of
operations are usually recommended and are performed in stages, usually starting
shortly after birth. In this series of operations, blood flow is redirected to the lungs
and the body with various surgical connections.
The surgical correction of pulmonary atresia with intact ventricular septum depends
on the degree of underdevelopment (hypoplasia of the tricuspid valve and right
ventricle). When hypoplasia is mild, the blocked pulmonary valve can sometimes be
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opened in the catheterization laboratory. More commonly, however, it is necessary to
undertake a surgical procedure with placement of a patch to enlarge the outflow part
of the right ventricle and the valve area. Generally, the patch is constructed using
the child's own natural tissue from around the heart (pericardium).
What is the long-term outlook after pulmonary atresia surgical repair?
The outlook varies from child to child. Follow-up care at a center 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.
Source: Children’s Hospital, Boston Cardiology Website, Accessible at:
http://www.childrenshospital.org/az/Site509/mainpageS509P0.html
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