Patent Ductus Arteriosus (PDA)
What is a patent ductus arteriosus (PDA)?
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PDA is a heart problem that is usually noted in the first few weeks
or months after birth. It is characterized by a connection between
the aorta and the pulmonary artery which allows oxygen-rich (red)
blood that should go to the body to recirculate through the lungs.
All babies are born with this connection between the aorta and
the pulmonary artery. While your baby was developing in the uterus,
it was not necessary for blood to circulate through the lungs
because oxygen was provided through the placenta. During pregnancy,
a connection was necessary to allow oxygen-rich (red) blood to
bypass your baby's lungs and proceed into the body. This normal
connection that all babies have is called a ductus arteriosus.
At birth, the placenta is removed when the umbilical cord is
cut. Your baby's lungs must now provide oxygen to his/her body.
As your baby takes the first breath, the blood vessels in the
lungs open up, and blood begins to flow through to pick up oxygen.
At this point, the ductus arteriosus is not needed to bypass the
lungs. Under normal circumstances, within the first few days or
weeks after birth, the ductus arteriosus closes and blood no longer
passes through it. Most babies have a closed ductus arteriosus
by 72 hours after birth.
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In some babies, however, the ductus arteriosus remains open (patent)
and becomes a problem, PDA. The opening between the aorta and
the pulmonary artery allows oxygen-rich (red) blood to pass back
through the blood vessels in the lungs.
PDA is the sixth most common congenital heart defect, occurring
in 5 to 10 percent of all children with congenital heart disease.
Patent ductus arteriosus occurs twice as often in girls as in
boys.
What causes patent ductus arteriosus?
In many children, there is no known reason for the ductus arteriosus
remaining open. However, PDA is seen more often in the following:
- premature infants
- infants born to a mother who had rubella during the first
trimester of pregnancy
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 often, a PDA occurs sporadically
(by chance), with no clear reason for its development.
PDA can also occur in combination with other heart defects.
Why is PDA a concern?
When the ductus arteriosus stays open, oxygen-rich (red) blood passes
from the aorta to the pulmonary artery, mixing with the oxygen-poor
(blue) blood already flowing to the lungs. The blood vessels in
the lungs have to handle a larger amount of blood than normal. How
well the lung vessels are able to adapt to the extra blood flow
depends on how big the PDA is and how much blood is able to pass
through it from the aorta.
Extra blood causes higher pressure in the blood vessels in the
lungs. The larger the volume of blood that goes to the lungs,
the higher the pressure. The lungs are able to cope with this
extra blood flow and pressure for a while, depending on exactly
how high the pressure is. Without medical treatment, however,
the blood vessels in the lungs become diseased by the extra pressure.
Further, because blood is pumped at high pressure through the
PDA, the lining of the pulmonary artery will become irritated
and inflamed. Bacteria in the bloodstream can easily infect this
injured area, causing a serious illness known as bacterial endocarditis.
What are the symptoms of a patent ductus arteriosus?
The size of the connection between the aorta and the pulmonary artery
will affect the type of symptoms noted, the severity of symptoms,
and the age at which they first occur. The larger the opening, the
greater the amount of blood that passes through that overloads the
lungs.
A child with a small patent ductus arteriosus might not have
any symptoms, and your child's physician may have only noted the
defect by hearing a heart murmur. Other infants with a larger
PDA may exhibit different symptoms. The following are the most
common symptoms of PDA. However, each child may experience symptoms
differently. Symptoms may include:
- fatigue
- sweating
- rapid breathing
- heavy breathing
- congested breathing
- disinterest in feeding, or tiring while feeding
- poor weight gain
The symptoms of a PDA may resemble other medical conditions or
heart problems. Always consult your child's physician for a diagnosis.
How is a patent ductus arteriosus diagnosed?
Your child's physician may have heard a heart murmur during a physical
examination, and referred your child to a pediatric cardiologist
for a diagnosis. A heart murmur is simply a noise caused by the
turbulence of blood flowing through the opening from the left side
of the heart to the right.
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. The cardiologist will perform
a physical examination, listening to the heart and lungs, and
make other observations that help in the diagnosis. The location
within the chest where the murmur is heard best, as well as the
loudness and quality of the murmur (harsh, blowing, etc.) will
give the cardiologist an initial idea of which heart problem your
child may have. However, other 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. With a PDA, the heart may be enlarged
due to larger amounts of blood flow through the lungs than normal.
Also, there may be changes that take place in the lungs due
to extra blood flow that can be seen on an x-ray.
- 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. An echo can show the pattern
of blood flow through the PDA, and determine how large the opening
is, as well as how much blood is passing through it.
- 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.
Treatment for patent ductus arteriosus:
Specific treatment for PDA 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
A small patent ductus arteriosus may close spontaneously as your
child grows. A PDA that causes symptoms will require medical management,
and possibly even surgical repair. Your child's cardiologist will
check periodically to see whether the PDA is closing on its own.
If a PDA does not close on its own, it will be repaired to prevent
lung problems that will develop from long-time exposure to extra
blood flow. Treatment may include:
- medical management
In premature infants, an intravenous (IV) medication called
indomethacin may help close a patent ductus arteriosus. Indomethacin
is related to aspirin and ibuprofen and works by stimulating
the muscles inside the PDA to constrict, thereby closing the
connection. Your child's physician can answer any further questions
you may have about this treatment.
As previously mentioned, some children will have no symptoms,
and require no medications. However, others may need to take
medications to help the heart and lungs work better. Medications
that may be prescribed include the following:
- digoxin - a medicine that helps strengthen the
heart muscle, enabling it to pump more efficiently.
- diuretics - the body's water balance can be affected
when the heart is not working as well as it could. These
medications help the kidneys remove excess fluid from the
body.
- adequate nutrition
Most infants with PDA eat and grow normally, but premature infants
or those infants with a large PDA may become tired when feeding,
and are not able to eat enough to gain weight. Options that
can be used to ensure your baby will have adequate 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,
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 may receive their formula
or breast milk through the feeding tube alone.
- surgical repair
The goal is to repair the patent ductus arteriosus before
the lungs become diseased from too much blood flow and pressure.
Repair is usually indicated in infants younger than 6 months
of age who have large defects that are causing symptoms, such
as poor weight gain and rapid breathing. For infants who do
not exhibit symptoms, the repair may often be delayed until
after 6 months of age. Your child's cardiologist will recommend
when the repair should be performed.
Your child's PDA may be repaired surgically in the operating
room or by a cardiac catheterization procedure. The surgical
repair, also called PDA ligation, is performed under general
anesthesia. The procedure involves closing the open PDA with
stitches to prevent the surplus blood from entering your child's
lungs.
The cardiac catheterization procedure may also be an option
for treatment. During the procedure, the child is sedated
and a small, thin, flexible tube (catheter) is inserted into
a blood vessel in the groin and guided to the inside of the
heart. Once the catheter is in the heart, the cardiologist
will pass a special device, called a coil or occluder, into
the open PDA preventing blood from flowing through it.
Postoperative care for your child:
Some children who undergo PDA ligation may need to spend some time
in the intensive care unit after surgery. Others may return to a
regular hospital room. Your child will be kept as comfortable as
possible with medications which relieve pain or anxiety. The staff
will also be asking for your input as to how best to soothe and
comfort your child.
You will also learn how to care for your child at home before your
child is discharged. The staff will give you instructions regarding
medications, activity limitations, and follow-up appointments before
your child is discharged. Most children will only need to stay in
the hospital for a few days after the operation.
Care for your child at home following PDA surgical repair:
Most infants and older children feel fairly comfortable when they
go home. 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.
Often, infants who fed poorly prior to surgery have more energy
after the recuperation period, and begin to eat better and gain
weight faster.
After surgery, older children usually have a fair tolerance for
activity. Your child will usually be allowed to play, while avoiding
blows to the chest that might cause injury to the incision or
breastbone. Within a few weeks, your child should be fully recovered
and able to participate in normal activity.
You will receive additional instructions from your child's physicians
and the hospital staff.
Long-term outlook after PDA surgical repair:
In premature infants, the outlook after PDA surgical repair depends
on the following:
- your child's gestational age
- any other illnesses present in your baby
In children born full-term, most who had a patent ductus arteriosus
repair will live healthy lives after recovering from the hospitalization.
Activity levels, appetite, and growth should return to normal.
Your child's cardiologist may recommend that antibiotics be given
to prevent bacterial endocarditis for a specific time period after
discharge from the hospital if the coil or occluder device was
used.
Consult your child's physician regarding the specific outlook
for your child.
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