1. Imaging Conference December 10, 2008 Angela Morello, M.D.
Atrial Septal Defects
Imaging Conference
December 10, 2008
Angela Morello, M.D.

2. Clinical Importance: Account for 10-15% of all congenital anomalies
Most common congenital defect to present in adulthood

3. Embryology
Braunwald, 6th Edition

4. Types of ASD’s Ostium Secundum Ostium Primum Sinus Venosus
Coronary sinus defects

5. 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

6. Associated findings: MVP (10-20%) EKG abnormalities: RAE
Prolonged PR interval
RAD (+100°)
rSR1 V1

7. 2D- Echocardiography: Secundum ASD

8. 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

9. Associated Findings: Cleft anterior leaflet of mitral valve: MR
EKG findings:
PR prolongation
RAE
LAD
rSR1 in V1-V2

10. Associated Findings: EKG

11. Primum ASD by TEE:

12. 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

13. 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

14. 2D-Echocardiography: Sinus Venosus Defect

15. 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

16. Pathophysiology continued:
Flow in systole and diastole
Bulk of flow in diastole
Size of ASD determines volume of shunting

17. 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

18. 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

19. 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)

20. 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

21. 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

22. Color Doppler:

23. Large Secundum ASD:

24. 2D-Echocardiography:

25. Associated findings by TTE:
Significant L--> R shunt
Right atrial enlargement
Right ventricular enlargement
Paradoxical septal motion (R sided volume overload)

26. 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

27. Doppler Echocardiography:
Volume Flow and Shunt calculation:
SV = CSA x VTI x 100
SI = SV/BSA
CO = SV x HR/ 1000
CI = CO/BSA

28. 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

29. 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

30. Color Doppler:

31. Color Doppler:

32. Color Doppler:

33. Color Doppler:

35. 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)

36. 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

37. 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

38. 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

39. 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

40. 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

45. Evaluation by Echo post-closure:
Assess residual shunting/flow
Assess for complications
Follow-up ventricular function

46. 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

47. 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

48. 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

49. THANK YOU!