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>> A patent ductus arteriosus or PDA
is a normal blood vessel that occurs in all infants
while they're still in their mother's womb.
It's a small blood vessel that allows the blood to bypass
the lungs that are not needed before they're born.
Once a baby is born, this blood vessel will normally
close down over the first two to three days of life.
This is stimulated by the increase in oxygen levels
and the drop in prostaglandins that are coming
from the placenta and inflation of the lungs.
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In premature infants, the PDA often is less likely
to close than it is in full-term infants.
This is due to a variety of reasons.
One is that there's less muscle
in the actual blood vessel wall to help it constrict down.
Also, in pre-term infants who have lung disease,
they don't get the same increase in oxygen
and drop in their pulmonary pressures.
PDAs are much more common, the more immature
and the smaller the babies are.
In infants who are born before 28 weeks gestation,
approximately two-thirds of these babies
will have a patent ductus arteriosus.
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If the PDA stays open, blood can flow
into the lungs causing over circulation
and potential congestive heart failure,
which can lead to worsening respiratory symptoms.
In addition, it can be a cause of severe hypotension
or low blood pressure.
In some cases, it can divert blood flow away
from vital organs such as the kidneys
and cause kidney failure.
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We have some medical therapies
that will close the PDA in our infants.
Medications we commonly use are indomethacin or ibuprofen.
These can be successful in about two-thirds of the cases.
Complications do occur with any medication
and can cause GI distress, decreased kidney function
and can also promote increased bleeding.
Other medications have been tried such as an acetaminophen,
but these have been shown to be less effective.
When medical treatment doesn't work
or the infant is too unstable to tolerate these medications,
we often proceed to a surgical procedure.
This requires the baby to have surgery to have
a ligation of this duct, so it's a opening of the chest.
Obviously, this can have lots of complications,
undergoing anesthesia, surgery, risk of infections
and bleeding, in addition to the concern
that there may be long-term developmental disabilities
associated with this procedure.
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Increase in evidence has been mounting,
but PDAs do not need to be treated as aggressively
as they have been historically.
As people have started to treat these less frequently,
they have found that looking at these infants
that they've tolerated not being treated,
and that they may have a better outcome.
But most of these studies have been criticized
because those infants not treated
may be the less sick infants
and thus be having the better outcome because of that.
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Research done at the John Hopkins Children's Center
is part of a multicenter trial was recently published.
This was a prospective randomized study
where infants who are born prematurely
who had a PDA were randomized
to either get the standard medical treatment
or to be monitored conservatively.
Those infants who were monitored conservatively
were allowed to have treatment
if they have showed evidence
of worsening respiratory symptoms,
hypotension or renal failure.
But what was interesting is that the need
for surgical ligation in both groups was identical.
And in fact, there was no increase risk in any
of the adverse outcomes such as necrotizing enterocolitis
or bronchopulmonary dysplasia,
that are often worried that they are associated with a PDA.
Those infants who were treated,
surprisingly ended up with higher rates of infection,
delays in their feeding and an increased mortality.
The result of the study is that it's now known
to be safe to monitor children who are asymptomatic
with a PDA to see if they'll allow them to slowly close
on their own without the worry of adverse long-term effects.
If they are symptomatic, such as the hypotension,
respiratory symptoms or renal failure,
it is appropriate to treat these infants.
Clearly for surgical treatment,
they need to be at a children's center
where the surgery can be done safely.
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