Download 12/07 Atrial Septal Defects

Atrial Septal Defects
Ali Mahajerin
Non-Invasive Cardiology Conference
December 12, 2007
Introduction
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Atrial septal defect (ASD) is detected in 1 child
per 1500 live births, and accounts for 5-10% of
congenital heart defects.
ASDs make up 30-40% of all congenital heart
disease detected in adults (second only to
bicuspid aortic valve).
ASDs occur in women 2-3 times as often as
men.
Introduction
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ASDs can occur in different anatomic portions
of the atrial septum.
ASDs can be isolated or occur with other
congenital cardiac anomalies.
Functional consequences of ASDs are related to
the anatomic location of the defect, its size, and
the presence or absence of other cardiac
anomalies.
Embryology
Classification
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Primum ASD
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Secundum ASD
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Sinus venosus defects
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Coronary sinus defects
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(Patent foramen ovale)
Primum ASD
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Make up ~15% of all ASDs.
Occur if the septum primum does not fuse with the
endocardial cushions, leaving a defect at the base of
the interatrial septum that is usually large.
Usually not isolated – primum ASDs are typically
associated with anomalies of the AV valves (such as
cleft mitral valve) and defects of the ventricular
septum (VSDs) or a common AV canal.
Secundum ASD
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Make up ~70% of all ASDs.
Occur twice as often in females.
Typically located within the area bordered by the
limbus of the fossa ovalis.
Defects vary in size, from <3 mm to >20 mm.
Secundum ASD
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May be associated with other ASDs.
Multiple defects can be seen if the floor of the fossa
ovalis (AKA valve of the foramen ovale) is
fenestrated.
Ten to twenty percent have a functional mitral valve
prolapse
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May be related to changing LV geometry associated with
RV volume overload
Sinus venosus ASD
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Make up ~10% of ASDs.
Characterized by malposition of the insertion of the
SVC or IVC straddling the atrial septum.
Often associated with anomalous pulmonary venous
return – the RUL/RML pulmonary veins may connect
with the junction of the SVC and RA in the setting of
a superior sinus venosus ASD.
Coronary Sinus Septal Defects
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Less than 1% of ASDs
Defects in the inferior/anterior atrial septum
region that includes the coronary sinus orifice.
Defect of at least a portion of the common wall
separating the coronary sinus and the left atrium
– AKA “unroofed coronary sinus”
Can be associated with a persistent left SVC
draining into the coronary sinus.
Patent Foramen Ovale
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Not truly an “ASD” because no
septal tissue is missing.
Oxygenated blood from the IVC
crosses the foramen ovale in utero.
At birth, the flap normally closes
due to
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Reduced right heart pressure and PVR
Elevated LA pressure.
Flap fusion is complete by age two
in 70-75% of children; the
remainder have a PFO.
Pathophysiology of ASDs
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Not an issue in utero – flow is occurring through the
foramen ovale.
After birth, generally LA pressure > RA pressure:
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PVR falls (lungs have expanded)
SVR rises (placenta has been removed)
Pulmonary venous blood flow is increased; all flows into LA
Left-to-right shunting occurs across the ASD – this
depends on the size of the defect, the relationship of
PVR and SVR, and the compliance of RV and LV.
Brief R-to-L shunting also occurs during cardiac cycle
in children (during inspiration, LA pressure decreased
and RA pressure increased) – causes mild neonatal
cyanosis.
Pathophysiology of ASDs
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Generally L-to-R flow across ASD
Occurs mainly in late ventricular systole and
early diastole; some augmentation during atrial
systole.
The volume of pulmonary blood flow is greater
than systemic blood flow because of this circuit.
Qp/Qs can be as high as 8:1, though in
asymptomatic young adults is usually 2:1 to 5:1.
Pathophysiology - consequences
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Right-sided volume overload leads to dilation of
right-sided chambers.
Main pulmonary arteries dilate, and pulmonary
vascularity is increased.
Eventual development of pulmonary
hypertension.
RV function can become decreased.
Eisenmenger syndrome, with RV failure and
right-to-left shunting of blood.
Clinical Manifestations
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Children may be asymptomatic; may have easy
fatigability, exertional dyspnea. Underdeveloped, more
prone to respiratory infections.
Most patients with shunt flow ≥ 2:1 will be
symptomatic and require correction by age 40.
Exercise intolerance, fatigue, dyspnea, and overt heart
failure are the common presentations in adulthood.
Risk of atrial arrhythmias increases with age and PA
pressure.
Pulmonary hypertension and Eisenmenger syndrome –
50% occurrence in unoperated ASDs.
Physical Exam Findings
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Wide, fixed splitting of S2 (delayed closure of
pulmonic valve with reduced respiratory variation)
Midsystolic pulmonary flow or ejection murmur
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Usually over 2nd intercostal space
Peaks in early-to-mid systole, ends before S2
Palpable RV heave
Usually no audible murmur across the ASD
Eisenmenger’s sequellae: cyanosis, clubbing
Murmur of MR if cleft MV also present (primum
ASD)
EKG Findings
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Right atrial enlargement d/t vol overload (tall P wave)
RVH – RAD, RSR’ in V1, R>S in V1.
Atrial tachyarrhythmias – a.fib, atrial flutter
AV delay – often with primum ASD in association
with LAFB and RBBB (the rim of an ostium primum
defect is near the His bundle).
Chest X-Ray Findings
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Dilation of RA and RV
Enlarged main
pulmonary arteries and
pulmonary vessels,
without redistribution
to apical vessels.
Left atrial enlargement
if associated mitral
regurgitation.
Echocardiography and ASDs
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Some clues to the presence of ASD:
Abrupt discontinuity of the septum, and slight
thickening at its termination
 RA enlargement, RV enlargement/dilation
 Dilated pulmonary arteries
 Increased flow velocity in the PA and across TV
 Paradoxical motion and diastolic flattening of the
ventricular septum
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TTE is usually definitive in secundum ASDs.
TEE will help with sizing defects, and
identifying sinus venosus defects.
Two-Dimensional TTE
Apical four-chamber view
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Can often see ostium primum
ASD in this view.
Shadowing and echo dropout
(especially in the area of the fossa
ovalis) may lead to false positives.
Subcostal view
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Often more reliable - can
visualize entire atrial septum.
Sensitivity for ASD detection:
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Primum ASD: 100%
Secundum ASD: 89%
Sinus venosus ASD: 44%
Color Doppler TTE
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Can confirm the presence of the
ASD, estimate the defect size, and
evaluate the efficacy of surgery.
Flow extends from mid-systole to
mid-diastole; second phase of flow
coincident with atrial systole.
May have brief R-L shunting.
Usually not a high velocity jet.
Must avoid confusing the lowvelocity shunt flow with normal
venous and AV valve flow.
Contrast Echo
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Administer agitated saline contrast through IV.
Apical four-chamber view is usually optimal.
Bubbles in the LA suggests right-to-left shunting
at the atrial level if 3 bubbles within 3 cardiac cycles
following complete opacification of the RA. Delayed
bubbles may be due to pulmonary AVMs – may be less
phasic in appearance.
Large ASDs may have nearly continuous shunting, but
smaller ASDs may be more phasic with respiration.
May see “negative contrast effect” if mainly left-toright shunt.
Contrast Echo - PFOs
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Often a small, hemodynamically insignificant
left-to-right shunt present in PFO based on the
unsealed overlap of foraminal valve.
The shunt is often phasic with respiration.
Maneuvers such as Valsalva or cough, which
transiently increase R heart pressure, may allow
the occult R-to-L shunt component of a PFO to
become evident.
Contrast Echo
Negative contrast effect
Transesophageal Echo
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TEE is superior to TTE in visualizing the interatrial
septum and identifying all types of ASDs.
With contrast or Doppler, TEE can detect any brief
right-to-left shunting that may occur with transient
increases in right-sided pressure.
TEE is much more sensitive than TTE for detection of
left-to-right shunt as negative right atrial contrast (93%
vs. 58% in one study).
TEE can detect flow through multiple ASDs.
Transesophageal Echo
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Estimation of defect size using the diameter of the
Doppler color flow jet correlates with surgical findings.
Since ASDs are not necessarily round, TEE helps with
determining both their size and shape. This is
especially important when percutaneous closure is
being contemplated.
TEE is often used when contrast echo suggests
shunting, but a defect can’t be visualized on TTE. The
TEE then helps to differentiate between a PFO and a
true ASD.
TEE is particularly helpful for diagnosis of sinus
venosus ASDs.
TEE
TEE
Cardiac MR
Can provide excellent details
regarding:
 Shunt flow
 Defect size
 Pulmonary venous return
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Large sinus venosus ASD
Qp/Qs 2.7
Anomalous return of right
upper pulmonary vein to RA
Increased RV cavity size,
normal RV function
Cardiac MR
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Qp/Qs = 2.0
Dilated RA, increased RV cavity size,
evidence of RV volume overload
Normal pulmonary veins
Cardiac MR
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Severely increased RV size, mild
RV free wall hypokinesis, volume
overload, dilated RA
No significant AR or MR,
normal LV
Sinus venosus ASD with
significant L-to-R shunt
Qp/Qs 3.03
Normal pulmonary venous
return – the right upper
pulmonary vein enters the LA at
its junction with the RA and
empties in the region of the
ASD.
Cardiac MR
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Large primum ASD, Qp/Qs 2.3;
possible associated membranous
VSD.
Normal LV cavity size; LVEF 66%,
effective forward LVEF 43%.
Increased RV size, RVEF 51%.
Main PA diameter 37
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Paradoxical interventricular septal
motion c/w RV volume overload
Mod-severe MR with likely cleft
anterior leaflet of MV
Biatrial enlargement
3D Echo
Estimation of Shunt Flow Ratio
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Operative closure of an ASD traditionally recommended
when the ratio of pulmonary blood flow to systemic
blood flow (Qp/Qs) is greater than 1.5:1 or 2:1.
Can estimate Qp/Qs from TTE measurements using
Pulsed Doppler echocardiography. Cardiac MR is also
useful for further assessment of Qp/Qs ratio.
Correlation between Doppler imaging and cardiac
catheterization techniques for this measurement is good.
Estimation of Shunt Flow Ratio
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First measure stroke volume through each valve:
Stroke Volume (Q) = CSA x VTI
Left-sided stroke volume is measured from LVOT
(diameter measured in parasternal long axis view).
 Maximum Doppler flow velocity apical to aortic
valve (VTILVOT) taken in apical four-chamber view.
 Right-sided velocity time integral (VTIPA) measured
in PA well before bifurcation.
 PA diameter measured at the same level as VTIPA.
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Estimation of Shunt Flow Ratio
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Substitution into stroke volume ratio gives:
Qp/Qs =
(PAdiam)2 x VTIPA
------------------------------------(LVOTdiam)2 x VTILVOT
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Diameters of LVOT and PA are squared – exact
measurement of these values is especially important.
PA diameter can be difficult to assess in some patients; this is
the term that is most often responsible for inaccurate
estimates of the shunt ratio.
Natural History of ASDs
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Most ASDs <8mm close spontaneously in infants.
Spontaneous closure is unusual in children and
adults; defects often become progressively larger.
Most patients with a significant shunt flow ratio
(Qp:Qs > 2:1) will be symptomatic and require
closure by age 40.
Increasing size of the ASD may preclude
percutaneous closure.
Natural History of ASDs
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Life expectancy is not normal, though many
patients live to advanced age.
Natural survival beyond age 40-50 is <50%.
The attrition rate after age 40 is ~6% per year.
Advanced pulmonary hypertension seldom
occurs before the third decade.
Atrial fibrillation is a late complication; stroke is
a potential complication of ASD (ongoing
investigation into this issue).
Indications for Defect Closure
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1.) Symptoms
Exercise intolerance, fatigue, dyspnea, heart failure
 Atrial tachyarrhythmias?
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Occur in 20% and often the presenting symptom
 Not an indication by itself (incidence may not be reduced
after surgery).
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Indications for Defect Closure
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2.) Defect Size and Qp/Qs
Larger ASDs impose a greater hemodynamic burden
on the RV.
 In the absence of pulmonary hypertension, Qp/Qs
is closely correlated with the size of the ASD.
 Qp/Qs > 2:1 is a well-established indication, though
many authors advocate 1.7:1 or even 1.5:1.
 AHA recommends a threshold Qp/Qs ≥ 1.5:1, but
these guidelines exclude patients > 21 years of age.
 Canadian Cardiac Society recommends Qp/Qs >2:1,
or >1.5:1 in the presence of reversible pulmonary
hypertension.
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Surgical Closure
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Median sternotomy is the
traditional approach; minimally
invasive approaches are emerging.
Pericardial or Dacron patches
are used.
Primary closure of the defect is not recommended.
Can repair other defects at the same time (such as cleft
mitral valve if primum ASD).
Intraoperative TEE useful to assess adequacy of repair;
can also assess for any new TR or MR that is occurring
from tension of the repair.
Surgery: Efficacy
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Does surgery still benefit patients who are older at the
time of diagnosis?
Attie et al. prospectively evaluated 473 pts. over age 40
diagnosed with secundum ASDs, randomized to
surgery vs. medical Rx
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Mean age 51
Median follow-up of 7.3 years.
Qp/Qs ratio 2.3 ± 0.7
Primary endpoints = death, PE, major arrhythmia, embolic
CVA, recurrent pulmonary infection, functional class
deterioration, or heart failure.
Attie F, et al. JACC 2001; 38(7): 2035-42.
Attie F, et al. JACC 2001; 38(7): 2035-42.
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Composite primary endpoint occurred more frequently with
medical than surgical therapy (21 vs 11 percent, H.R. 2.0).
Overall mortality not statistically different, but there was a
nonsignificant trend toward higher sudden death rate with
medical treatment (2.9 vs 0.9 percent).
Multivariate analysis (adjusted for age at entry, mean PASP >
35 mmHg, previous atrial tachyarrhythmia, and C.I. < 3.5
L/m2) had a significantly higher mortality with medical
management (H.R. 4.1).
Surgery: Efficacy
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Konstantinides et al. retrospectively evaluated 179
patients with isolated ASDs diagnosed after age 40
(91% secundum, 3% primum, 6% sinus venosus)
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Compared 84 pts. (47%) who underwent surgery vs. 95
pts. (53%) who were treated medically.
Mean age 54±7 years for the surgery group, 57±10 years
for the medical therapy group.
Mean follow-up period 8.9±5.2 years
Cardiac symptoms reported in 94% at presentation.
“The decision not to operate was based on the judgment
of the cardiologists and cardiac surgeons involved in
each case.”
Konstantinides S, et al. NEJM 1995; 333(8): 469-73.
Konstantinides S, et al. NEJM 1995; 333(8): 469-73.
Surgery: Efficacy
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Multivariate analysis revealed a reduced mortality from
all cause in the surgical group (relative risk 0.31; 95%
C.I. 0.11-0.85).
Ten-year survival rate was 95% in surgical group, 84%
in medically treated group.
Surgical treatment prevented functional deterioration
(11% vs. 34%, relative risk 0.21, 95% C.I. 0.08-0.55)
and improved functional status (32% vs. 3%, p=0.002).
Incidence of new atrial arrhythmias or stroke was not
significantly different.
Konstantinides S, et al. NEJM 1995; 333(8): 469-73.
Long-Term Surgical Outcomes
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Surgery before the age of 25 yields in 30-year survival
rates comparable to age- and sex-matched controls.
At 25-40 years of age, surgical survival is reduced,
though not significantly if PA pressures are normal.
If PASP > 40 mmHg, late survival is 50% less than
control rates, though life expectancy in surgically
treated older patients is better than that of medically
treated patients.
No benefit of surgery in reducing the incidence of AF,
though the patient’s age at the time of closure is the
most important predictor of the development of atrial
arrhythmias.
Percutaneous Closure
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An alternative to surgical closure
for secundum ASDs with
appropriate anatomic
characteristics.
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Defect < 30mm diameter
Prefer a rim of tissue at least 5mm
around the defect to prevent
obstruction of coronary sinus, R
pulmonary veins, vena cavae, or AV
valves.
Approximately half to two-thirds
of secundum ASDs in adults
meet these criteria.
Amplatzer Occlusion Device
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Introduced in 1996.
Approved for percutaneous
ASD closure in 2001 by F.D.A.
Over 90,000 have been
manufactured and delivered to
date.
Consists of two round disks
made of Nitinol (nickel +
titanium) wire mesh linked
together by a short connecting
waist.
Amplatzer Occlusion Device
Advantages over other devices:
 Can be delivered through smaller
catheters
 It is self-centering but can be
repositioned easily
 Has round retention disks that
extend radially beyond the defect,
which results in a much smaller
overall size and firmer contact
with the atrial septum
 Shape enhances endothelialization
and reducing the risk of residual
shunting
Secundum ASD
Secundum ASD
Amplatzer - catheter
Amplatzer – crossing the septum
Amplatzer – deployment of left atrial
disc
Amplatzer – seating against
interatrial septum
Amplatzer – deployment of right
atrial disc
Amplatzer – releasing the device
Amplatzer – minimal residual shunt
Post-Procedure TTE
Post-Procedure TTE
Post-Procedure TTE
Post-Procedure TTE
Percutaneous Closure - Outcomes
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Chan et al. showed successful implantation of
Amplatzer device in 93 of 100 patients (mean age 13.3
years).
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Procedure time ranging 30 to 180 minutes.
Seven failures
Total ASD occlusion rate at 3 months = 99% for the 93
successes.
Masura et al. showed no deaths or significant
complications, along with all defects remaining
completely closed, in 151 patients (mean age 11.9 years)
at long-term follow-up (median time 78 months).
Chan KC, et al. Heart 1999; 82(3): 300-6.
Masura J, et al. JACC 2005; 45(4): 505-7.
Percutaneous Closure - Complications
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Early complications
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Thrombus formation (both in LA and RA)
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Device embolization or malposition requiring surgery (2.4%)
Atrial fibrillation (2.4%)
Heart block, effusion, thrombus in LAA (2.2%)
Need aspirin and plavix for at least 6 months
Rare complications: cardiac perforation, sudden death
Long-term complication: device erosion (0.1% of
cases) – risk factors include deficient aortic rim (25/28
cases), deficient superior rim, and oversized device.
Surgery vs. Percutaneous Repair?
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Du et al. evaluated 596 patients with secundum ASDs
and Qp/Qs ≥ 1.5:1 – surgery vs. Amplatzer ASO
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Nonrandomized; assigned according to patient’s option.
Median age 9.8 years in Amplatzer arm (442 patients), 4.1
years surgical arm (154 patients; p<0.001)
Twelve-month follow-up
Procedural success significantly higher with surgery
(100 vs. 96 percent, p=0.006).
Percutaneous closure had significant reduction in
complication rates (7 vs. 24 percent) and mean hospital
stay (1.0 vs. 3.4 days).
Mortality 0% for both groups.
Du ZD, et al. JACC 2002; 39(11): 1836-44.
Surgery vs. Percutaneous Repair?
Du ZD, et al. JACC 2002; 39(11): 1836-44.
Surgery vs. Percutaneous Repair?
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Bialkowski et al. prospectively compared closure
and complication rates in 91 children with
secundum ASDs over mean follow-up 3.9 years.
Mean age 8.1±4.7 years for surgery (44 pts.),
10.1±4.9 years for Amplatzer (47 pts.)
 Surgery if ASDs unsuitable for percutaneous
closure; 3 patients’ parents also requested surgery.
 Closure rate similar in the two groups (95.5% vs.
97.5%).
 Hospital stay 7.5 days vs. 2.2 days (p<0.001)
 No deaths reported.
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Bialkowski J, et al. Tex Heart Inst J 2004; 31: 220-3.
Surgery vs. Percutaneous Repair?
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Mild complications: small pericardial effusions,
headaches, AV delay, atrial rhythm disturbances
Moderate complications: pneumonia, paroxysmal SVT, AV
junctional rhythm
Severe complications: bleeding requiring reoperation,
transient neurologic events.
Bialkowski J, et al. Tex Heart Inst J 2004; 31: 220-3.
Surgery vs. Percutaneous Repair?
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Butera et al. retrospectively evaluated 1268 patients with
secundum ASDs.
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Surgical group: mean age 22.4±18.9 years (range 1-81 years), female-male
ratio 393:124.
Percutaneous group: mean age 29±19.8 years (range 9 mo-81 years),
female-male ratio 415:336.
No post-operative deaths.
Overall complications higher for surgery (44 vs. 6.9 percent,
p<0.0001).
Surgery was independently strongly related to the occurrence of
total complication (OR 8.13, 95% CI 5.75-12.20) and of major
complications (OR 4.03, 95% CI 2.38-7.35).
Hospital stay was shorter for percutaneous closure (3.2±0.9 vs.
8.0±2.8 days, p<0.0001).
Butera G, et al. AHJ 2006; 151: 228-34.
Surgery vs. Percutaneous Repair?
Butera G, et al. AHJ 2006; 151: 228-34.
Surgery vs. Percutaneous Repair?
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Most reports show comparable procedural
success.
Rate of complications is consistently lower with
percutaneous closure.
Percutaneous closure associated with shorter
hospital stays.
Many centers prefer implantation of
percutaneous device to surgical repair when
percutaneous approach seems feasible.
Stroke Risk?
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Data are widely conflicting on the relationship between
PFO, atrial septal aneurysm, and/or ASD and recurrent
cerebral emboli.
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Increased prevalence of PFO and ASA in cryptogenic stroke;
less clear for ASD.
The role of defect closure vs. medical therapy for
prevention of recurrent stroke is not well defined.
Aspirin is often used in setting of PFO or an isolated
atrial septal aneurysm, and especially if PFO + ASA.
Role of coumadin is not as clear – coumadin
recommended if patient has a documented DVT/PE.
Less data available for ASDs.
Surgical excision of an atrial septal aneurysm (without
PFO or ASD) may be considered if aspirin or coumadin
fail to prevent a recurrent embolic event.
Endocarditis Prophylaxis?
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The 2007 AHA guidelines do not recommend
antibiotic prophylaxis of endocarditis in isolated ASD,
with the following exceptions:
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Recently repaired ASD, whether by prosthetic material or
device, during the first 6 months after repair (to allow for
sufficient endothelialization).
Repaired ASD with a residual defect at the site or adjacent to
the site of a prosthetic device.
The updated guidelines no longer include associated
mitral regurgitation as an indication for prophylaxis.
Prophylaxis is no longer recommended for GI or GU
procedures; above criteria apply to dental procedures or
respiratory procedures that require biopsy of mucosa.
Wilson W, et al. Circulation 2007; 151: 1-19.
Thank You!
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Eli Gelfand
Jason Ryan