Patent Ductus Arteriosus (PDA): A Parent's Guide
Page 2 How is
a PDA treated?
There are several treatment strategies for a PDA. The
treatment that is best for any individual child depends
on several factors, the most important of which is the
child's age.
Premature Infants: Most children who become
seriously ill with congestive heart failure in the
newborn period are premature infants in whom the ductus
does not close at all. There are two treatment options
for these babies.
1. Indomethacin Therapy: This is a medication
that is in the same class of drugs as aspirin and
ibuprofen (Non-Steroidal Anti-Inflammatories). The
indomethicin (sometimes called "indocin") works
by indirectly stimulating the muscles of the ductus to
contract. This medicine works in a large percentage of
premature infants. As with any other medication,
indomethicin has side effects which may include internal
bleeding and kidney dysfunction. In many babies,
treatment with indomethicin may be repeated if the first
course is not successful, and if there are no side
effects.
2. Surgical Therapy: If indomethicin is
ineffective, or if the child cannot receive the
medication due to other medical problems, surgical
treatment of the PDA is indicated in almost all cases.
The first surgical closure of PDA was accomplished in
1938. The transcatheter techniques that will be described
below are not generally applicable in premature infants
due to the small size of the heart and blood vessels.
With the baby under general anesthesia, the surgeon
enters the chest from under the left arm, and isolates
the PDA. If the PDA has enough length to it, the optimal
surgical technique is to tie a suture (or place a
surgical staple) around the PDA at both ends, and to cut
the PDA between the two sutures. This prevents the PDA
from re-opening later on. In some cases, the PDA is very
short. In these newborns, the surgeon may only be able to
fit a single suture. A surgical series from Scandinavia
reported up to a 20% recurrence rate with this technique.
Surgical closure of PDA is very reliable, has few
complications, and is safe in even the smallest premature
infants.
Infants and Children with PDA: It is rare for
full term infants, or for older children to have
congestive heart failure symptoms from a PDA, though it
certainly can occur. Similar to the premature infants,
there are significant size issues in children less than 6
months of age, especially those who are growing poorly
due to congestive heart failure. Many institutions prefer
the surgical option for children under 6 months of age
who have signs of heart failure. For children older than
6 months who are otherwise well, surgery has been
virtually eliminated due to successes with the newer
transcatheter closure techniques.
Transcatheter Closure of PDA: There have been
many devices developed for the closure of a PDA without
surgery. These devices date back to the early 1970's when
Dr. Porstmann first described such a device. This device
was extremely bulky and carried very high complication
risks. Since that time, several other devices have been
developed for the purpose of closing the PDA.
Rashkind Device: The first device to gain
widespread popularity was developed by Dr. William
Rashkind. Though never approved by the FDA for use in the
United States, the device is still in use in other
countries. This device is made up of two tiny sponge
umbrellas which are attached to one another. When
positioned correctly, the device "straddles"
the PDA, with one umbrella on the aortic side of the PDA
and one on the pulmonary artery side. The size of each
umbrella is larger than the orifice of the PDA, so the
device cannot move. The umbrellas become coated with
blood and quickly become non-porous. Eventually the
natural tissue lining of the blood vessels grows to cover
the device so that blood travelling past it does not
"know" it is there.
This device was quite successful in closing small
PDA's (> 90% success rate), but was limited by the
large catheter sizes required for delivery. This
precluded its use in small children. The device was
removed from trials in the U.S. in 1992.
Coil Occlusion Techniques: In 1992, with the
Rashkind device unavailable for closure of PDA's, Dr.
John Moore first described the technique of closing a PDA
with a device called a Gianturco coil.
| The coil is essentially a spring made of
surgical steel which is imbedded with dacron
fibers over its entire length. The coil has been
in clinical use since 1972, and has a long record
of successful closure of other blood vessels
(bleeding ulcers, brain tumors, etc.). It was
only in 1992 however, that the coil was first
applied to a PDA. |
 |
 |
The principle of the coil is similar to that
of the Rashkind device. The coil loops are larger
than the size of the PDA opening. Once loops are
placed on each side of the PDA, the spring holds
it in position while the dacron fibers allow
formation of a clot which eliminates flow through
the PDA. The coil is then covered by the vessel
lining, as is the case with the Rashkind device. |
In contrast to the Rashkind device, the coil can be
delivered through a catheter as small as 1.3 mm in
diameter (4 French catheter), can be done in small
babies, and is usually done as an outpatient procedure.
The coil procedure has achieved success rates of over 95%
in most series. This procedure has gained extraordinary
world-wide support in a very short period of time.
There have been several techniques described for coil
delivery, each of which has its own set of advantages and
disadvantages:
1) Transarterial approach: The original
method of Dr. Moore. A single catheter is placed in the
artery of the leg, and advanced to the chest to deliver
the coil. With this technique, the most significant risks
in early publications related to coil positioning. With
no reliable method for repositioning or removing the
coil, inaccurate placement lead to incomplete closure,
and "embolization" of the coil into the lungs
(an unstable coil may be pushed out of the PDA by the
force of the blood flow trying to get through) in up to
15% of early procedures. As the catheterizing physicians
became more experienced, the risk of losing the coil into
the lungs decreased. Larger PDA's were too difficult to
attempt closure with this original technique. With a
catheter in the artery, a very small percentage of
children, particularly those under 10 kg, had
complications involving the circulation to the leg, a
transient problem.
2) Transvenous approach: Originally
described by Dr. Ziyad Hijazi, in this technique the
artery is not used. Rather the catheter(s) are introduced
through the vein in the leg, avoiding any potential
complications with the artery. While not using the artery
was seen as an advantage, this technique was originally
criticized for the increased potential to lose the coil
into the aorta, with the potential for blocking flow to a
vital structure (kidney, leg, intestinal artery, etc.).
This was an infrequent complication.
3) Snare-assisted delivery: This technique,
developed by Dr. Robert Sommer, uses a special snare
catheter (a catheter with a cowboy's lasso on the end of
it) to hold the coil while it is delivered. This allows
precise positioning and repositioning of the coil (if
necessary), resulting in higher closure rates. It allows
for the testing of the coil stability in the PDA prior to
release, and as a result, eliminates the complications of
coil "embolization", in which the coil is
pushed by the blood flow out of the PDA to the lungs.
This complication occurred in as many as 15% of cases in
early series. The use of the snare has been criticized as
an unnecessary cost in patients with small PDA's.
4) Retrievable coil techniques: Special coils
are used which can be detached only when they are stable
in the proper position. These coils, while less likely to
embolize, also seemed to have lower rates of complete
closure. Newer versions of these coils are soon to be on
the market.
5) Grifka-Gianturco "bag": For larger
PDA's that were not ideal for coil closure, Dr. Ron
Grifka developed a "bag" attached to the end of
the catheter into which the coils are placed. This
technique has been very successful, but is only
applicable in PDA's with substantial length.
6) 0.052 inch coils: Dr. Phillip Moore first
described the use of thicker coils for the closure of
larger PDA's. The principle of using a thicker coil was
that it would take up more space within the PDA, and
would therefore obstruct blood flow more effectively
within the PDA. This has been quite successful in closing
larger PDA's.
7) Latson Catheter: Dr. Larry Latson has
developed a delivery catheter which allows for reliable
coil removal and/or repositioning (similar to the
retrievable coils) in the event that the coil is not
optimally straddling the PDA.
Still other, newer devices are being developed for
closure of the PDA. None are yet approved for general use
by the FDA, but some have started testing in the U.S. and
abroad.
Any technique that can be used in older children is
equally applicable to the rare adult patient diagnosed
with a PDA. We have used the coil occlusion technique in
adults up to 76 years of age, when they presented with
symptoms for the first time in adulthood.
The specific technique of transcatheter PDA closure
that is best for your child depends on the PDA size and
shape, the size of your child, and the techniques with
which your pediatric cardiologists are most comfortable.
Surgical Techniques
Traditional Surgical Approach: An incision
5-7cm in length is made and the chest is entered by
spreading the fourth and fifth ribs apart. The PDA is
then identified by clearing away the surrounding tissue,
taking care to avoid injury to the nerves which go to the
voicebox and the diaphragm (the phrenic nerve). A stitch
is then tied around the PDA on both the aortic end and
the pulmonary artery ends of the ductus (ligation), which
is then cut in the middle (division) if there is enough
length. Ligation and division yields the lowest incidence
of recurrence (<1%).
Thoracoscopic Approach: Several centers have
published series in which a small telescope is used to
guide the surgical closure of the PDA. In the
thoracoscopic approach, two or three smaller incisions
(1cm) are made to facilitate the imaging and surgical
equipment, rather than the single larger incision of the
traditional approach. The results are comparable to the
standard thoracotomy approach that remains the gold
standard. This technique, however, requires special
equipment and surgical training not available at most
centers, and seems to offer few advantages over
traditional surgery.
Muscle Sparing Thoracotomy: Newer techniques
for cardiac surgery have resulted in the miniaturization
of instruments and have allowed significant reduction in
the size of the surgical incision. These
"muscle-sparing" or minimally invasive
techniques have resulted in faster patient recovery times
and shorter hospitalizations. In some centers, these
surgeries are being done on an ambulatory basis.
Regardless of the surgical approach, hospital stays are
seldom more than overnight.
Summary
The diagnosis of Patent Ductus Arteriosus (PDA) is
relatively common, affecting 1 in 2,000 children. While
the majority of children do not have symptoms, the risks
are nonetheless real. It is comforting for parents to
know that no matter which technique is employed for
treating this problem of their child's heart, after
closure of the PDA, the circulation is normal, and the
child will have a normal heart with no further risks for
the remainder of a normal life.
This article was reviewed prior to publication by:
Lucian A. Durham, III, M.D., Ph.D.
Director, Pediatric Cardiovascular Surgery
Strong Children's Heart Center
University of Rochester Medical Center
William B. Moskowitz, M.D.
Director of Pediatric Cardiac Catheterization
Laboratory
Medical College of Virginia
Parent/ACHD Reviewers:
Wanda and Ray Tinetti
Leah Weinstein
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