Atrial Septal Defects
By
Thomas Mutanikwa
Salem akram
Clinical Importance:
• Account for 10-15% of all congenital
anomalies
• Most common congenital defect to present
in adulthood
Types of ASD’s
• Ostium Secundum
• Ostium Primum
• Sinus Venosus
• Coronary sinus defects
Ostium Secundum ASD:
• Most common type (70-75%)
• 7% of all congenital heart defects = 5-6 cases per
10,000 live births
• Female predominance 2:1
• Two common mechanisms:
• Inadequate formation of septum secundum to not
completely cover ostium secundum
• Excessively large ostium secundum due to increased
resorption; septum secundum can therefore not cover
Associated findings:
• EKG abnormalities:
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RAE
Prolonged PR interval
RAD (+100°)
rSR1 V1
2D- Echocardiography:
Secundum ASD
Ostium Primum ASD:
• Mostly in trisomy 21--> 1/800 live births
• 40-50% Down’s pts have CHD: 65% of these are
AV canal defects
• Simplest form of AV canal defect (often associated
with more advanced/complicated forms)
• Female: male predominance is 2:1
• Located at most anterior and inferior aspect of the
atrial septum
• Formed by:
• Ostium primum remains from septum primum
• Usually sealed by fusion with endocardial cushions
• Failure to fuse endocardial cushions--> associated AV
valve abnormalities
Associated Findings:
• Cleft anterior leaflet of mitral valve: MR
• EKG findings:
• PR prolongation
• RAE- right atrium enlargement
• LAD-left axis deviation
Primum ASD by TEE:
Sinus Venosus Defect:
• Not truly considered an ASD
• Only accounts for 10% of all “ASD’s”; 1% of all
congenital defects in U.S.
• Abnormal resorption of sinus venosus in
development
• Two types:
• “Usual” type: upper atrial septum contingous with SVC
• Less common: at junction of RA and IVC
• Associated findings:
• anomalous pulm venous drainage into RA or vena
cavae
• junctional/low atrial rhythm
Associated Findings:
• Anomalous pulmonary venous drainage into
RA or vena cavae
• In “usual” type, RUPV drains to SVC
• In less common type, RLPV drains to IVC
• Junctional/low atrial rhythm
2D-Echocardiography:
Sinus Venosus Defect
Pathophysiology:
• Left to right shunting: Qp/Qs > 1.5/1.0
• Dependent on defect size and relative diastolic
filling properties of the ventricles
• Decreased ventricular compliance +/- increased
left atrial pressure --> increase in shunting
• Decrease ventricular compliance:
 Systemic hypertension
 Cardiomyopathy
 MI
• Increase LA pressure:
 Mitral valve disease
Pathophysiology continued:
• Flow in systole and diastole
• Bulk of flow in diastole
• Size of ASD determines volume of shunting
Presentation:
• Often asymptomatic until 3-4th decade for
moderate-large ASD
• Fatigue
• DOE:
• 30% by 3rd decade
• 75% by 5th decade
• Atrial arrhythmias/SVT and R sided HF:
• 10% by 4th decade
• Increase therafter with age
• Paradoxical Embolus:
• Transient flow reversal (Valsalva/strain)
• Pulmonary Hypertension
Echocardiographic Evaluation:
• Subcostal view most reliable: US beam
perpendicular to plane of IAS
• Other views may have loss of signal from the atrial
septum from parallel alignment
• Secundum ASD: central portion of atrial septum
(89% sensitivity)
• Primum ASD: adjacent to AV valve annuli (100%
sensitivity)
• Sinus Venosus defects: difficult to visualize on
TTE (44% sensitivity)
Echo in Secundum ASD:
• Identify the following:
• normal coronary sinus
• entrance of pulmonary veins
• intact primum portion of atrial septum
Echo in Primum ASD:
• “Drop-out” of inferior portion of IAS can be
seen on apical 4 or subcostal views
• TV NOT more apically positioned than
MV; at same horizontal level
• Color to differentiate from dilated coronary
sinus
• PW and CW Doppler to estimate RVSP and
PA pressures
2D-Echocardiography:
Associated findings by TTE:
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Significant L--> R shunt
Right atrial enlargement
Right ventricular enlargement
Paradoxical septal motion (R sided volume
overload)
Doppler Echocardiography:
• Color Doppler can identify left to right flow
• Subcostal view is best
• Multiple views needed:
• Low-velocity flow signal between atria
• SVC flow along IAS can be mistaken for
shunting
• TR jet directed toward IAS
Color Doppler:
• Location and timing of flow critical
• Flow from L--> R atrium in both systole and
diastole
• More prominent diastolic component
• Can extend across open TV in diastole into RV
• Flow acceleration on side of LA
• Absolute velocity of flow less important
Contrast Echocardiography:
• Microbubbles seen across IAS
• Even if shunting predominantly L to R
• RA pressure transiently > LA pressure
• “Negative” contrast jet:
• Flow from LA to RA appears as area with no
echo contrast
• Rarely needed for ASD - more useful for
smaller shunts (PFO’s)
Indications for Intervention:
• Asymptomatic in the presence of:
• Right-sided cardiac dilatation
• ASD > 5mm with no signs of spontaneous closure
• Hemodynamics reserved for “borderline” cases
 HD insignificant (Qp/Qs <1.5) - no closure required until
later in life for embolism prevention after CVA
 HD significant (Qp/Qs >1.5) - should be closed
Indications for Interventions
continued…
• Closure can be recommended IF:
• Net L--> R shunt of 1.5:1 or greater
• Pulmonary artery reactivity upon challenge with
pulmonary vasodilator
• Lung biopsy evidence of reversibility to pulmonary
arterial changes
Interventional Options:
• Percutaneous closure procedure of choice
when appropriate
• Similar indications for closure as discussed
• Only available for Secundum ASD with
stretched diameter < 41 mm
• Need adequate rims to enable secure device
deployment
• Cannot have anomalous pulm venous
connection, be too proximal to AV valves,
coronary sinus, or systemic venous drainage
Percutaneous Closure:
• Amplatzer device
• Introduced by AGA
Medical in 1996
• Nitinol wire mesh with
middle “waist”
• Amplatzer septal occluder
• Single defects
• Amplatzer fenestrated
septal occluder
(“Cribiform”)
• Multiple hole ASD
• Thinner central waist
Role of echo in percutaneous
closure:
• TEE used in past, but requires general anesthesia
• Intracardiac echo:
• Mullen et al, JACC 2003
• Feasability and accuracy of ICE in guiding
percutaneous closure of ASDs
• Prospective study of 24 pts; using ICE as primary
imaging modality
• Close agreement to TEE
• Successful guidance in 96% of cases
• Identify residual shunts in 98% of cases
• Detected 100% of adverse events
Evaluation by Echo postclosure:
• Assess residual shunting/flow
• Assess for complications
• Follow-up ventricular function
Complications/ Results:
• < 1% of cases with complications
• Includes device embolization, atrial
perforation, thrombus formation
• Clinical closure achieved in > 80% of cases
• Improves functional status and exercise
capacity
Early and Intermediate
Follow-up:
• Medical management:
• ASA
• Bacterial endocarditis prophylaxis x 6 months
• F/U Echo 1 year (after immediate post study
done to confirm success)
• Device vs Surgery:
• Overall similar costs and success/safety
• Likely due to expense of device
• Shorter hospital course with device
Surgical Treatment:
• Reserved for cases that are not candidates for
percutaneous closures:
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Non-secundum ASDs
Secundum ASDs with unsuitable anatomy
Primary suture vs tissue/synthetic patch
Symptomatic improvement seen
Does not prevent AF/aflutter in adults (especially >40
years old)
• Concomitant MAZE a consideration
THANK YOU!