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PATENT DUCTUS ARTERIOSUS (PDA): CURRENT MANAGEMENT
PDA is relatively common, accounting for nearly 10% of congenital heart defects in childhood. It often
exists as an isolated defect and is mostly small to moderate in size. PDA presents in 2 general
circumstances: the pre-term neonate, and infants, children or adults with heart murmurs detected on
routine physical examination
Anatomy and Physiology
The PDA is a vascular communication between the descending thoracic aorta and the main pulmonary
artery, near the origin of the left pulmonary artery. Tt is an essential structure for normal development in
the fetus. In an infant delivered at term, the PDA closes normally within hours to days after birth. In
subjects with defects in the muscular wall of the PDA, the closure process fails to occur, and the ductus
arteriosus stays open, or patent. In infants born prematurely, the ductus may be unresponsive to the
physiologic stimuli and closure mechanisms operational at term. In that setting, persistent patency of
the ductus may complicate post-natal respiratory function, feeding and bowel perfusion.
PDA in the pre-term infant. In the very pre-term infant the PDA is often large. A large PDA not only
causes persistent pulmonary hypertension by equalizing aortic and pulmonary artery pressures, but also
can markedly increase pulmonary blood flow and rob the systemic circulation of flow and oxygen delivery.
Respiratory distress, ventilator dependence, poor systemic perfusion and necrotizing enterocolitis are all
consequences of a large PDA. Because the PDA is large, flow through it is non-turbulent, and a heart
murmur may not be present. For that reason, echocardiography is necessary to document or exclude a
PDA. Indomethacin may be prescribed by the neonatologist to interfere with the prostaglandin cascade
that helps maintain ductal patency prior to term. If one or more courses of indomethacin are not effective,
surgery (usually performed in the NICU) may be needed. Trans-catheter intervention is not used in this
setting.
PDA in the infant, child and adult
Postnatally, a PDA usually is small to moderate in size. When that is the case, pulmonary and aortic
pressures separate in systole and diastole, resulting in the characteristic machinery quality continuous
heart murmur characteristic of a PDA.
Why close a PDA if it is only small or moderate in size?
A PDA of moderate size can result in elevation of pulmonary artery pressure to the extent that pulmonary
vascular obstructive disease may develop over years or decades. In addition, a moderate PDA can
precipitate congestive symptoms and interfere with growth. With a small PDA, controversy existed until
recently about whether or not trans-catheter closure was justified. However, modern series of infective
endocarditis (IE) cases in children and adults have shown the PDA (often small and undiagnosed prior to
presentation with IE) is a cause of IE> These series from developing countries (Ethiopia, Pakistan), where
routine early screening examinations may not be available to all residents, show the most common cardiac
condition associated with IE is rheumatic valve disease, but the most common congenital cardiac lesion in
patients with IE is the unrecognized small PDA. For this reason, most pediatric cardiologists now
recommend PDA closure, even if the PDA is small. At weights over 6 kg (~13 lb.), the PDA can be closed
safely and completely with one of a variety of vascular occlusion devices delivered by a trans-catheter,
out-patient approach. These include vascular occlusion coils of varying size and configuration, nylon
bag-like devices containing a coiled stainless steel wire, and compressible plugs constructed of the
nickel-titanium alloy, nitinol.
Of the approximately 100 interventional procedures we perform each year at Presbyterian Hospital, about
25% involve closure of a PDA.
PDA in the infant or child with Down syndrome
Infants and children with Down syndrome have a high incidence of congenital cardiac disease. Although AV
canal/septation defects are most common, isolated PDA does occur in these patients. Moreover, the
pulmonary vascular resistance (and therefore pulmonary artery pressure) may remain elevated in infants
with Down syndrome for months to years after birth. This pulmonary hypertension may be exacerbated
by ventilation issues. Because of the elevated pulmonary artery pressure, flow through a large, medium or
small size PDA may be non-turbulent, resulting in no significant heart murmur. For this reason, it is
recommended that any infant with Down syndrome have an echocardiogram to exclude congenital heart
disease. If a child with Down syndrome is found to have a PDA, post occlusion treatment with oxygen or
drugs may be required to reduce persistent pulmonary hypertension.
In conclusion, PDA is a common congenital cardiac lesion that may complicate the course and survival of
small pre-term neonates or cause heart failure, pulmonary hypertension or IE in older infants, children and
adults. Out of the neonatal period, PDA closure is accomplished in nearly all instances by a trans-catheter
approach. The procedure has been a safe and definitive one in our hands. In the infant or child with Down
syndrome, echocardiography is often required to determine whether or not a PDA is present. Because of
the increased availability and use of echocardiograms in the pediatric population, the prevalence of
pulmonary vascular disease due to an unrecognized moderate or large PDA has fallen dramatically in the
modern medical era.
PDA is relatively common, accounting for nearly 10% of congenital heart defects in childhood. It often
exists as an isolated defect and is mostly small to moderate in size. PDA presents in 2 general
circumstances: the pre-term neonate, and infants, children or adults with heart murmurs detected on
routine physical examination
Anatomy and Physiology
The PDA is a vascular communication between the descending thoracic aorta and the main pulmonary
artery, near the origin of the left pulmonary artery. Tt is an essential structure for normal development in
the fetus. In an infant delivered at term, the PDA closes normally within hours to days after birth. In
subjects with defects in the muscular wall of the PDA, the closure process fails to occur, and the ductus
arteriosus stays open, or patent. In infants born prematurely, the ductus may be unresponsive to the
physiologic stimuli and closure mechanisms operational at term. In that setting, persistent patency of
the ductus may complicate post-natal respiratory function, feeding and bowel perfusion.
PDA in the pre-term infant. In the very pre-term infant the PDA is often large. A large PDA not only
causes persistent pulmonary hypertension by equalizing aortic and pulmonary artery pressures, but also
can markedly increase pulmonary blood flow and rob the systemic circulation of flow and oxygen delivery.
Respiratory distress, ventilator dependence, poor systemic perfusion and necrotizing enterocolitis are all
consequences of a large PDA. Because the PDA is large, flow through it is non-turbulent, and a heart
murmur may not be present. For that reason, echocardiography is necessary to document or exclude a
PDA. Indomethacin may be prescribed by the neonatologist to interfere with the prostaglandin cascade
that helps maintain ductal patency prior to term. If one or more courses of indomethacin are not effective,
surgery (usually performed in the NICU) may be needed. Trans-catheter intervention is not used in this
setting.
PDA in the infant, child and adult
Postnatally, a PDA usually is small to moderate in size. When that is the case, pulmonary and aortic
pressures separate in systole and diastole, resulting in the characteristic machinery quality continuous
heart murmur characteristic of a PDA.
Why close a PDA if it is only small or moderate in size?
A PDA of moderate size can result in elevation of pulmonary artery pressure to the extent that pulmonary
vascular obstructive disease may develop over years or decades. In addition, a moderate PDA can
precipitate congestive symptoms and interfere with growth. With a small PDA, controversy existed until
recently about whether or not trans-catheter closure was justified. However, modern series of infective
endocarditis (IE) cases in children and adults have shown the PDA (often small and undiagnosed prior to
presentation with IE) is a cause of IE> These series from developing countries (Ethiopia, Pakistan), where
routine early screening examinations may not be available to all residents, show the most common cardiac
condition associated with IE is rheumatic valve disease, but the most common congenital cardiac lesion in
patients with IE is the unrecognized small PDA. For this reason, most pediatric cardiologists now
recommend PDA closure, even if the PDA is small. At weights over 6 kg (~13 lb.), the PDA can be closed
safely and completely with one of a variety of vascular occlusion devices delivered by a trans-catheter,
out-patient approach. These include vascular occlusion coils of varying size and configuration, nylon
bag-like devices containing a coiled stainless steel wire, and compressible plugs constructed of the
nickel-titanium alloy, nitinol.
Of the approximately 100 interventional procedures we perform each year at Presbyterian Hospital, about
25% involve closure of a PDA.
PDA in the infant or child with Down syndrome
Infants and children with Down syndrome have a high incidence of congenital cardiac disease. Although AV
canal/septation defects are most common, isolated PDA does occur in these patients. Moreover, the
pulmonary vascular resistance (and therefore pulmonary artery pressure) may remain elevated in infants
with Down syndrome for months to years after birth. This pulmonary hypertension may be exacerbated
by ventilation issues. Because of the elevated pulmonary artery pressure, flow through a large, medium or
small size PDA may be non-turbulent, resulting in no significant heart murmur. For this reason, it is
recommended that any infant with Down syndrome have an echocardiogram to exclude congenital heart
disease. If a child with Down syndrome is found to have a PDA, post occlusion treatment with oxygen or
drugs may be required to reduce persistent pulmonary hypertension.
In conclusion, PDA is a common congenital cardiac lesion that may complicate the course and survival of
small pre-term neonates or cause heart failure, pulmonary hypertension or IE in older infants, children and
adults. Out of the neonatal period, PDA closure is accomplished in nearly all instances by a trans-catheter
approach. The procedure has been a safe and definitive one in our hands. In the infant or child with Down
syndrome, echocardiography is often required to determine whether or not a PDA is present. Because of
the increased availability and use of echocardiograms in the pediatric population, the prevalence of
pulmonary vascular disease due to an unrecognized moderate or large PDA has fallen dramatically in the
modern medical era.
Interventional Catheterization
THERAPEUTIC INTERVENTION DURING CARDIAC CATHETERIZATION
(Interventional Cardiac Catheterization)
William Berman, Jr., M.D.
HISTORY
Prior to the mid-1940’s, surgery was not an option for infants and children with
congenital heart disease. Development of cardio-pulmonary bypass in the mid-
50s made intracardiac surgical repairs an option. In 1961, Dr. John Kirklin at the
Mayo clinic performed the first VSD repair in an infant. Accurate pre-operative
diagnosis became essential for optimal surgical results. Beginning in the 1960’s,
prior to modern 2D echocardiography, cardiac catheterization was used in children
to provide accurate anatomic and hemodynamic diagnoses prior to surgery. Until
relatively recently, catheterization was a diagnostic tool, not a treatment modality.
That changed when Dr. William Rashkind at the Children’s Hospital of Philadelphia
performed a balloon atrial septostomy in an infant with transposition of the great
vessels. That procedure ushered in the age of therapeutic, or interventional,
cardiac catheterizations. These are procedures that provide treatment in addition
to invasive diagnosis. In 1982, Dr. Jean Kan at Johns Hopkins Hospital in
Baltimore performed the first balloon pulmonary valveplasty in a child with
pulmonic stenosis. During the intervening 24 years, the field of interventional
cardiac catheterization has grown in scope and complexity. At most institutions
with comprehensive pediatric cardiology practices, including our own, interventional
catheterization procedures outnumber purely diagnostic catheterizations. In many
programs, the number of therapeutic catheterizations approximates or exceeds
the number of cardiac surgical procedures performed in children. I would like to
review the experience of Pediatric Cardiology Associates (PCA) in this area and
indicate the direction of our growth.
Our interventional program began in 1985 when PCA physicians practiced at the
University Hospital. The vast majority of our experience has occurred at
Presbyterian Hospital where we have practiced since 1993. Currently, Dr. Bill
Berman performs all our interventional procedures.
PHILOSOPHY
We reserve therapeutic cardiac catheterization for cases
in which the anticipated outcome will be equal to or better,
and the risk will be equal to or less, than surgical
intervention.
OUR DATA
Through 2008, we have performed a total of 1196 interventional cardiac
catheterizations. Early during our experience, 20-30 cases were performed
annually. During the past several years, we have averaged approximately 90
interventional catheterizations per year in a program where approximately 130
pediatric cardiac surgeries are performed annually. Therapeutic catheterizations
now exceed diagnostic procedures performed in the catheterization laboratory.
CASE MIX
Early in our experience, dilatation of stenotic pulmonary and aortic valves with
balloon tipped catheters accounted for the majority of interventions. As the
discipline of interventional catheterization evolved, procedures were developed to
close communications such as the patent ductus arteriosus (PDA) and atrial septal
defect (ASD) with implantable devices passed through a cardiac catheter. More
recently, stents, constructed of expandable metal materials, have been used to
enlarge stenotic vessels including branch pulmonary stenosis and aortic
coarctation. Accordingly, the kinds of lesions treated in the catheterization
laboratory have changed. In 2008, 56% of cases involved implantation of a device
(ASD/PFO device, coil or stent). Whereas no PDA’s were closed at catheterization
prior to the mid-1990’s and no ASD’s were closed prior to the late 1990’s, those
2 procedures alone accounted for over 50% of our interventions in 2008.
AGE MIX
As the spectrum of conditions treated has changed with time, so has the age at
which we treat our patients. During our initial experience, predominantly infants
and children were treated during interventional catheterization. Currently, with the
availability of implantable devices and stents, more adults undergo intervention in
the “pediatric catheterization laboratory”. In 2008, 25% of patients who
underwent an interventional procedure were over 18 years old.
REPRESENTATIVE CASES IN 2008
Pulm. valve, conduit, RV outflow stenosis 17
Peripheral pulmonary stenosis 11
Aortic valve stenosis and coarctation 6
Atrial septal defect/patent foramen ovale 27/3
Patent ductus arteriosus/coil embolization 14/6
FURTURE DIRECTIONS
THE PATENT FORAMEN OVALE (PFO)
Currently, trans-catheter closure of the PFO is restricted by the FDA to a very
narrow spectrum of patients, namely individuals who sustain a paradoxical
embolus, have a patent foramen ovale with right to left shunting on trans-
esophageal echocardiographic study, and who sustain a subsequent embolic
episode or episodes while on anticoagulation with coumadin or aspirin and
clopidogrel. At this time, a single occult embolic stroke or myocardial infarction,
even with a confirmed PFO and right to left atrial level shunting, does not qualify a
patient to receive a trans-catheter closure device (even though surgery is an
option). Controlled trials are under way to test the safety and efficacy of the
trans-catheter approach, compared to historical surgical controls and patients
undergoing systemic anticoagulation with coumadin. Moreover, the PFO
increasingly is implicated in other conditions, most notably migraine headaches and
decompression illness. We anticipate our adult caseload will increase if and when
the trans-catheter closure device is approved for a broader spectrum of subjects.
VALVEPLASTIES AND STENT IMPLANTATIONS
Major recent advances have occurred in the equipment available to the pediatric
interventionalist. Catheters, sheaths and balloon dilatation devices have all been
downsized for application in neonates and small infants. Some investigators have
applied these devices to the fetal setting, where narrowed vessels or valves are
addressed in utero. Constraints that once existed related to vessel damage and
size limitation no longer are a major concern. These equipment options broaden
our scope of practice in the interventional laboratory.
HYBRID INTERVENTIONS
Currently, trans-catheter devices are being tested in selected centers for VSD
closure, palliation of infants with hypoplastic left heart, and completion of the
Fontan procedure for treatment of patients with a single functional ventricle. In
some centers, especially Chicago Children’s Hospital, Miami Children’s Hospital, and
Columbus Children’s Hospital, the practicality of hybrid procedures involving both
surgery and therapeutic catheterization is being tested. One such procedure is the
trans-cardiac closure of large muscular VSD’s, using an open chest approach
without cardiopulmonary bypass. Initial results are very impressive. The
cooperative efforts of surgeons and interventionalists during a single case is both
sensible and exciting as a future direction of the discipline.
TRANS-CATHETER VALVE REPLACEMENT
Dr. Philip Bonhoffer, initially from Germany but now working in London, has led the
development and implementation of tissue valves placed in the pulmonary position
by a trans-catheter approach. The valves, which are large venous valves obtained
from cows, are mounted inside expandable stents. The system has been refined
to the point that a clinical trial is underway in Great Britain to test the valves’
safety, effectiveness and durability. Again, initial results are promising.
BENEFITS OF INTERVENTIONAL CATHETERIZATION IN CHILDREN
The main benefit of interventional catheterization is that it obviates the need for
cardiac surgery in many instances. Of the 1200 interventional catheterizations
performed by our physicians, surgery was avoided entirely in an estimated 2/3 of
patients. The cost of an interventional catheterization is 1/3 to 1/2 that of
surgery. The vast majority of patients go home the same day, without the need
for hospitalization. While the overall mortality/morbidity risks are probably only
slightly less than for surgery, interventions are nearly painless, leave no scars and
don't require blood transfusions. To insure the highest quality and best
outcomes, the American Heart Association, the American College of Cardiology and
the Society of Cardiac Angiography and Interventions (SCAI) have stated (in
separate guidelines) that interventional procedures in infants and children must be
performed only at facilities where pediatric cardiology surgical back-up is
immediately available, and the volume of cases is high enough to permit
consistency and excellence. At Presbyterian Hospital, we meet or exceed all
published guidelines for a catheter-based interventional program.
(Interventional Cardiac Catheterization)
William Berman, Jr., M.D.
HISTORY
Prior to the mid-1940’s, surgery was not an option for infants and children with
congenital heart disease. Development of cardio-pulmonary bypass in the mid-
50s made intracardiac surgical repairs an option. In 1961, Dr. John Kirklin at the
Mayo clinic performed the first VSD repair in an infant. Accurate pre-operative
diagnosis became essential for optimal surgical results. Beginning in the 1960’s,
prior to modern 2D echocardiography, cardiac catheterization was used in children
to provide accurate anatomic and hemodynamic diagnoses prior to surgery. Until
relatively recently, catheterization was a diagnostic tool, not a treatment modality.
That changed when Dr. William Rashkind at the Children’s Hospital of Philadelphia
performed a balloon atrial septostomy in an infant with transposition of the great
vessels. That procedure ushered in the age of therapeutic, or interventional,
cardiac catheterizations. These are procedures that provide treatment in addition
to invasive diagnosis. In 1982, Dr. Jean Kan at Johns Hopkins Hospital in
Baltimore performed the first balloon pulmonary valveplasty in a child with
pulmonic stenosis. During the intervening 24 years, the field of interventional
cardiac catheterization has grown in scope and complexity. At most institutions
with comprehensive pediatric cardiology practices, including our own, interventional
catheterization procedures outnumber purely diagnostic catheterizations. In many
programs, the number of therapeutic catheterizations approximates or exceeds
the number of cardiac surgical procedures performed in children. I would like to
review the experience of Pediatric Cardiology Associates (PCA) in this area and
indicate the direction of our growth.
Our interventional program began in 1985 when PCA physicians practiced at the
University Hospital. The vast majority of our experience has occurred at
Presbyterian Hospital where we have practiced since 1993. Currently, Dr. Bill
Berman performs all our interventional procedures.
PHILOSOPHY
We reserve therapeutic cardiac catheterization for cases
in which the anticipated outcome will be equal to or better,
and the risk will be equal to or less, than surgical
intervention.
OUR DATA
Through 2008, we have performed a total of 1196 interventional cardiac
catheterizations. Early during our experience, 20-30 cases were performed
annually. During the past several years, we have averaged approximately 90
interventional catheterizations per year in a program where approximately 130
pediatric cardiac surgeries are performed annually. Therapeutic catheterizations
now exceed diagnostic procedures performed in the catheterization laboratory.
CASE MIX
Early in our experience, dilatation of stenotic pulmonary and aortic valves with
balloon tipped catheters accounted for the majority of interventions. As the
discipline of interventional catheterization evolved, procedures were developed to
close communications such as the patent ductus arteriosus (PDA) and atrial septal
defect (ASD) with implantable devices passed through a cardiac catheter. More
recently, stents, constructed of expandable metal materials, have been used to
enlarge stenotic vessels including branch pulmonary stenosis and aortic
coarctation. Accordingly, the kinds of lesions treated in the catheterization
laboratory have changed. In 2008, 56% of cases involved implantation of a device
(ASD/PFO device, coil or stent). Whereas no PDA’s were closed at catheterization
prior to the mid-1990’s and no ASD’s were closed prior to the late 1990’s, those
2 procedures alone accounted for over 50% of our interventions in 2008.
AGE MIX
As the spectrum of conditions treated has changed with time, so has the age at
which we treat our patients. During our initial experience, predominantly infants
and children were treated during interventional catheterization. Currently, with the
availability of implantable devices and stents, more adults undergo intervention in
the “pediatric catheterization laboratory”. In 2008, 25% of patients who
underwent an interventional procedure were over 18 years old.
REPRESENTATIVE CASES IN 2008
Pulm. valve, conduit, RV outflow stenosis 17
Peripheral pulmonary stenosis 11
Aortic valve stenosis and coarctation 6
Atrial septal defect/patent foramen ovale 27/3
Patent ductus arteriosus/coil embolization 14/6
FURTURE DIRECTIONS
THE PATENT FORAMEN OVALE (PFO)
Currently, trans-catheter closure of the PFO is restricted by the FDA to a very
narrow spectrum of patients, namely individuals who sustain a paradoxical
embolus, have a patent foramen ovale with right to left shunting on trans-
esophageal echocardiographic study, and who sustain a subsequent embolic
episode or episodes while on anticoagulation with coumadin or aspirin and
clopidogrel. At this time, a single occult embolic stroke or myocardial infarction,
even with a confirmed PFO and right to left atrial level shunting, does not qualify a
patient to receive a trans-catheter closure device (even though surgery is an
option). Controlled trials are under way to test the safety and efficacy of the
trans-catheter approach, compared to historical surgical controls and patients
undergoing systemic anticoagulation with coumadin. Moreover, the PFO
increasingly is implicated in other conditions, most notably migraine headaches and
decompression illness. We anticipate our adult caseload will increase if and when
the trans-catheter closure device is approved for a broader spectrum of subjects.
VALVEPLASTIES AND STENT IMPLANTATIONS
Major recent advances have occurred in the equipment available to the pediatric
interventionalist. Catheters, sheaths and balloon dilatation devices have all been
downsized for application in neonates and small infants. Some investigators have
applied these devices to the fetal setting, where narrowed vessels or valves are
addressed in utero. Constraints that once existed related to vessel damage and
size limitation no longer are a major concern. These equipment options broaden
our scope of practice in the interventional laboratory.
HYBRID INTERVENTIONS
Currently, trans-catheter devices are being tested in selected centers for VSD
closure, palliation of infants with hypoplastic left heart, and completion of the
Fontan procedure for treatment of patients with a single functional ventricle. In
some centers, especially Chicago Children’s Hospital, Miami Children’s Hospital, and
Columbus Children’s Hospital, the practicality of hybrid procedures involving both
surgery and therapeutic catheterization is being tested. One such procedure is the
trans-cardiac closure of large muscular VSD’s, using an open chest approach
without cardiopulmonary bypass. Initial results are very impressive. The
cooperative efforts of surgeons and interventionalists during a single case is both
sensible and exciting as a future direction of the discipline.
TRANS-CATHETER VALVE REPLACEMENT
Dr. Philip Bonhoffer, initially from Germany but now working in London, has led the
development and implementation of tissue valves placed in the pulmonary position
by a trans-catheter approach. The valves, which are large venous valves obtained
from cows, are mounted inside expandable stents. The system has been refined
to the point that a clinical trial is underway in Great Britain to test the valves’
safety, effectiveness and durability. Again, initial results are promising.
BENEFITS OF INTERVENTIONAL CATHETERIZATION IN CHILDREN
The main benefit of interventional catheterization is that it obviates the need for
cardiac surgery in many instances. Of the 1200 interventional catheterizations
performed by our physicians, surgery was avoided entirely in an estimated 2/3 of
patients. The cost of an interventional catheterization is 1/3 to 1/2 that of
surgery. The vast majority of patients go home the same day, without the need
for hospitalization. While the overall mortality/morbidity risks are probably only
slightly less than for surgery, interventions are nearly painless, leave no scars and
don't require blood transfusions. To insure the highest quality and best
outcomes, the American Heart Association, the American College of Cardiology and
the Society of Cardiac Angiography and Interventions (SCAI) have stated (in
separate guidelines) that interventional procedures in infants and children must be
performed only at facilities where pediatric cardiology surgical back-up is
immediately available, and the volume of cases is high enough to permit
consistency and excellence. At Presbyterian Hospital, we meet or exceed all
published guidelines for a catheter-based interventional program.
| Atrial septal dilatation |
| AMPLATZER® ASD Occluder |
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| |
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| |
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| |
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| |
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| |
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| |
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| |
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| Partially deployed |
| Fully deployed and released from delivery cable |
| PEDIATRIX CARDIOLOGY ASSOCIATES OF NEW MEXICO |
| PDA |
| After Coil Occlusion |
*
| PDA closure with Amplatzer PDA device |