Download Patent Ductus Arteriosus

Chris Burke, MD
PATENT DUCTUS ARTERIOSUS
What is the Ductus Arteriosus?
Ductus Arteriosus
 Allows blood from RV to bypass fetal lungs
 Between the main PA (or proximal left PA)
and the descending thoracic aorta
 Maintains patency in utero by low O2 tension
and high circulating prostaglandin levels
Ductus Arteriosus
 During final trimester, ductus becomes much
less sensitive to prostaglandins
 Following birth, rise in O2 tension and lack of
placental prostaglandins usually results in
closure
 Usually complete by 12-24 hours, but
sometimes days-weeks
 Becomes ligamentum arteriosum
Patent Ductus Arteriosum
 Roughly 1 out of 1200 live births, more
common in premature infants thought to
be related to immature ductal wall being less
sensitive to O2 tension
 Constitutes 7% of congenital heart defects
 Desirable in some defects including many
cyanotic heart lesions; this has led to the use
of PGE4 clinically
Pathophysiology
 Shunt volume
determined by the size
of ductus and ratio of
pulmonary to systemic
vascular resistance
 PVR declines over first
several weeks of life,
increasing left-to-right
shunt across PDA
 Excessive shunting can
lead to right heart
failure
Pathophysiology
 Over time, pulmonary
vascular obstructive
disease will develop
 Eisenmenger syndrome
is the end result, when
shunting reverses to
right-to-left; this is
associated with
irreversible pulmonary
hypertension and
cyanosis, eventually
leading to RV failure
Morphologies
Clinical Manifestations
 Infants with large shunt volume may develop
CHF leading to tachypnea, tachycardia, and
poor feeding
 Physical exam findings include: widened
pulse pressure and continuous “machinery
murmur”, heard best along the left sternal
border radiating to the back
Clinical Manifestations
 CXR may show increased pulmonary
markings and left heart enlargement
 EKG may have LVH and/or left atrial
enlargement
 Echo diagnostic method of choice
 Diagnostic cardiac catheterization generally
only performed in adults to evaluate for
pulmonary hypertension
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Treatment
 Pharmacologic
 Endovascular
 Surgical
Considerations
 Closure is performed for all symptomatic
patients with left-to-right shunt
 Indications for closure in Asx patients:
 signs of left heart volume overload
 reversible pulmonary hypertension
 murmur
 Closure NOT recommended when
Eisenmenger physiology is present or PDA is
silent (controversial)
Considerations
 In patients with PVR greater than 8 Woods
Units, closure is generally not recommended
 This is especially true when right-to-left or bidirection flow is present or elevated PVR not
reversed with high O2 or iNO
 This can lead to catastrophic RV failure, due
to loss of “pop-off” mechanism
Pharmacologic Closure
 Indomethacin, a prostaglandin inhibitor, can
be used to close a PDA
 0.1-0.2 mg/kg IV at 12 or 24- hour intervals for
a total of three doses
 Rarely effective in term infants
 80% effective in premature infants
Surgical Closure
 Dates back to 1939
 Generally reserved for infants and children
with lesions deemed unsuitable for
percutaneous closure
 Good choice for larger PDAs (~ 8mm)
 Posterolateral thoracotomy classically, but
VATS approach described
Percutaneous Closure
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First performed in 1967
Access via femoral artery or vein
Most commonly use coils or occlusion devices
Proven benefit with PDAs < 3mm
Major limitation of these techniques is ductus
size in one study a PDA diameter greater
than 4mm had a 24-fold increased risk of
incomplete closure
 Morphology is another significant issue!
Percutaneous Closure
Percutaneous Closure
Surgical Closure Still Has a
Role
 Galal et al reported a 20% conversion or
failure rate with 236 attempted percutaneous
closures
 Hsiao et al reported reduced number of
ventilator days and improved outcomes in
VLBW (<1500 g) premies that underwent
early (<14 days old) versus late (>14 days old)
surgical repair
Management Summary
 Who gets closed?
 Sxs with left-to-right shunt
 Audible murmur
 Reversible pulmonary HTN
 Left sided volume overload/heart failure
Management Summary
 Premies indomethacin; surgery if
unsuccessful
 Term infants medical treatment to
optimize for percutaneous closure; if this
fails, then surgery
 Children/Adults: in general, percutaneous
closure