Patent
Ductus Arteriosus (PDA)
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.
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 6 to 11 percent of all children with
congenital heart disease. Patent ductus arteriosus
occurs twice as often in girls as in boys.
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.
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.
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.
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.
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.
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.
- PDA repair or closure
The majority of infants and children with PDA
are candidates for repair in the cardiac cath
lab. The goal is to repair the PDA 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.
Transcatheter coil closure of the PDA is frequently
used because it is minimally invasive. However,
premature infants are not candidates for this
procedure.
Your child's PDA may be repaired surgically
in the operating room. 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. Alternately,
the vessel connecting the aorta and pulmonary
artery may be cut and cauterized (sealed off
by burning with an electrical instrument).
- cath lab repair/closure
procedure
When the procedure is complete, the catheter(s)
will be withdrawn. Several gauze pads and a
large piece of medical tape will be placed on
the site where the catheter was inserted to
prevent bleeding. In some cases, a small, flat
weight or sandbag may be used to help keep pressure
on the catheterization site and decrease the
chance of bleeding. If blood vessels in the
leg were used, your child will be told to keep
the leg straight for a few hours after the procedure
to minimize the chance of bleeding at the catheterization
site.
Your child will be taken to a unit in the hospital
where he/she will be monitored by nursing staff
for several hours after the test. The length
of time it takes for your child to wake up after
the procedure will depend on the type of medicine
given to your child for relaxation prior to
the test, and also on your child's reaction
to the medication.
After the procedure, your child's nurse will
monitor the pulses and skin temperature in the
leg or arm that was used for the procedure.
Your child may be able to go home after a specified
period of time, providing he/she does not need
further treatment or monitoring. You will receive
written instructions regarding care of the catheterization
site, bathing, activity restrictions, and any
new medications your child may need to take
at home.
- surgical repair
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.
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.
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 that had a patent ductus
arteriosus diagnosed and repaired early 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.
In children
whose PDA was diagnosed late and/or never repaired,
the outlook is uncertain. There is a risk for
pulmonary hypertension (increased blood pressure
in the blood vessels of the lungs). These individuals
should receive follow-up care at a center that
specializes in congenital heart disease.
Consult
your child's physician regarding the specific
outlook for your child.
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