atrial septal defects

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


• Volume Flow and Shunt calculation:

• SV = CSA x VTI x 100• SI = SV/BSA• CO = SV x HR/ 1000• CI = CO/BSA


• 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


• 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


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

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!

atrial septal defects

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