What is a patent ductus arteriosus (PDA)?
Patent mean "open". The ductus arteriosus
is a blood vessel connecting the main vessel leading to the lungs (pulmonary
artery) to the main vessel of the body (aorta).
Why does a baby have a ductus
arteriosus?
Before birth, the mother and placenta take care of
the oxygen needs of the fetus (baby before birth). The fetus does not need to
use his/her lungs. Therefore, very little blood needs to go to the lungs to help
them grow. The ductus arteriosus allows most of the blood to bypass the lungs
and go the rest of the body. After birth, the baby must use his/her lungs to
take in oxygen and get rid of carbon dioxide. Now, the blood from the pulmonary
artery needs to go to the lungs to pick up oxygen instead of going through the
ductus arteriosus. Normally after birth the ductus gradually narrows and then
closes in the first few hours to days. In premature infants, especially those
who have had respiratory distress syndrome, this blood vessel may stay open.
What happens if this blood vessel stays open?
Blood goes in the opposite direction through this
vessel than it would in the fetus. It goes from the aorta to the lungs. In
addition, there is normal blood flow from the heart to the lungs. This is too
much blood into the baby's lung. Fluid in the lung increases and it makes it
harder for the baby to breathe. The PDA increases the work of the heart and the
baby can develop heart failure if the amount of blood flowing through the PDA is
large. How will doctors know if my baby has a PDA?
Your doctors may suspect your baby has a PDA if :
-
s/he needs more oxygen or help breathing when
s/he should be needing less
-
his/ her breathing is more difficult or there
is much more apnea
-
the doctor or nurse hears a murmur (an abnormal
noise over the heart)
-
the baby's heart rate increases and/or the
pulse changes
If a PDA is suspected, your baby will probably have
an ECHOCARDIOGRAM. In this test sound waves are used to give a picture of the
baby's heart and determine the amount of blood flow through the PDA. It is
painless and is similar in principle to the ultrasound that many women have when
they are pregnant.
How is a PDA treated?
-
If the ductus is very small and there is only a
tiny amount of blood flowing through it, your baby's doctors may wait to see
if it closes on its own.
-
The most common drug used to treat a PDA is
indomethacin. It causes the ductus to narrow. As the ductus narrows, less
blood flow can go through it. Indomethacin may also cause your baby to make
less urine. Sometimes more than one course of indomethacin is needed to
close a ductus. Some physicians use ibuprofen instead of indomethacin.
-
Your doctor might also decide to decrease the
amount of fluid that your baby is receiving while the PDA is open.
-
Occasionally another drug called a diuretic is
given to decrease the fluid in the lungs and increase the amount of urine
that your baby makes.
What happens if medical treatment doesn't work?
If the ductus will not close with medication, or if
your baby's doctors do not think your baby should have these drugs, the PDA may
be tied off (ligated) surgically through an incision in the baby's chest.
Does my baby have a heart malformation (abnormal
development)?
It is very rare for a baby to also have a heart
malformation. A PDA in a premature baby is not considered a malformation. The
echocardiogram will determine if your baby's heart is otherwise normal.
Will the PDA come back?
Sometimes drugs only close the ductus for hours or
a few days. A second course may be needed, or surgery may be required. However,
once the baby is over his/her problems of prematurity and the PDA has gone away,
it will not come back later in life.
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