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

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

Embryology Braunwald, 6th Edition

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: MVP (10-20%) EKG abnormalities: 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 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: Cleft anterior leaflet of mitral valve: MR EKG findings: PR prolongation RAE LAD rSR1 in V1-V2

Associated Findings: EKG

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

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: 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 RV and RA size and function

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:

Large Secundum ASD:

2D-Echocardiography:

Associated findings by TTE: 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

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: 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: 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:

Color Doppler:

Color Doppler:

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… 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: 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 post-closure: 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: 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

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