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Atrial Septal Defects Atrial Septal Defects
Imaging Conference
December 10, 2008
Angela Morello, M.D.
Clinical Importance:Clinical Importance:
• Account for 10-15% of all congenital anomalies
• Most common congenital defect to present in adulthood
EmbryologyEmbryology
Braunwald, 6th Edition
Types of ASD’sTypes of ASD’s
• Ostium Secundum
• Ostium Primum
• Sinus Venosus
• Coronary sinus defects
Ostium Secundum ASD: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:Associated findings:
• MVP (10-20%)
• EKG abnormalities:• RAE
• Prolonged PR interval
• RAD (+100°)
• rSR1 V1
2D- Echocardiography:Secundum ASD
2D- Echocardiography:Secundum ASD
Ostium Primum 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 1:1• 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:Associated Findings:
• Cleft anterior leaflet of mitral valve: MR
• EKG findings:• PR prolongation• RAE• LAD• rSR1 in V1-V2
Associated Findings: EKGAssociated Findings: EKG
Primum ASD by TEE:Primum ASD by TEE:
Sinus Venosus Defect: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: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 Defect2D-Echocardiography:Sinus Venosus Defect
Pathophysiology: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 hypertensionCardiomyopathyMI
• Increase LA pressure:Mitral valve disease
Pathophysiology continued:Pathophysiology continued:
• Flow in systole and diastole
• Bulk of flow in diastole
• Size of ASD determines volume of shunting
Presentation: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
Physical Findings:Physical Findings:
• “Left atrialization” of JVP (A=V wave)
• Hyperdynamic RV impulse
• PA tap
• S2 wide/fixed split
• Grade II SEM: increased flow through TV
Echocardiographic Evaluation: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:Echo in Secundum ASD:
• Identify the following:• normal coronary sinus• entrance of pulmonary veins• intact primum portion of atrial septum
• RV and RA size and function
Echo in Primum ASD: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
Color Doppler:Color Doppler:
Large Secundum ASD:Large Secundum ASD:
2D-Echocardiography:2D-Echocardiography:
Associated findings by TTE:Associated findings by TTE:
• Significant L--> R shunt
• Right atrial enlargement
• Right ventricular enlargement
• Paradoxical septal motion (R sided volume overload)
Doppler Echocardiography: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
Doppler Echocardiography:Doppler Echocardiography:
• Volume Flow and Shunt calculation:
• SV = CSA x VTI x 100• SI = SV/BSA• CO = SV x HR/ 1000• CI = CO/BSA
Doppler Echocardiography:Doppler Echocardiography:
• Shunt calculation:• Can be performed utilizing these equations to
relate pulmonic CO and systemic CO• Qp = TVI pulm X PULd• Qs = TVI ot X LVOTd• Qp/Qs = shunt fraction• Significant usually if > 1.5/1.0 in ASD
Color Doppler: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
Color Doppler:Color Doppler:
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Color Doppler:Color Doppler:
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Color Doppler:Color Doppler:
QuickTime™ and aMicrosoft Video 1 decompressorare needed to see this picture.
Color Doppler:Color Doppler:
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QuickTime™ and aMicrosoft Video 1 decompressorare needed to see this picture.
Contrast Echocardiography: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:Indications for Intervention:
• Asymptomatic in the presence of:
• Right-sided cardiac dilatation
• ASD > 5mm with no signs of spontaneous closure
• Hemodynamics reserved for “borderline” casesHD insignificant (Qp/Qs <1.5) - no closure required until
later in life for embolism prevention after CVAHD significant (Qp/Qs >1.5) - should be closed
Indications for Interventions continued…
Indications for Interventions continued…
• In presence of PA HTN:• Defined as PAP > 2/3 systemic or PVR > 2/3
SVR• 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: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: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:
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
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QuickTime™ and aMicrosoft Video 1 decompressorare needed to see this picture.
QuickTime™ and aMicrosoft Video 1 decompressorare needed to see this picture.
QuickTime™ and aMicrosoft Video 1 decompressorare needed to see this picture.
Evaluation by Echo post-closure:
Evaluation by Echo post-closure:
• Assess residual shunting/flow
• Assess for complications
• Follow-up ventricular function
Complications/ Results: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:
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:Surgical Treatment:
• Reserved for cases that are not candidates for percutaneous closures:
• 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!THANK YOU!