Atrial septal defect
- Many ASDs go undiagnosed in childhood
- From superior to inferior, ASDs occur in:
- Sinus venosus (5%)
- Ostium secundum (75%), ostium primum (15-20%)
- Very rarely coronary sinus ASD
- Spontaneous closure in up to 40% of patients within the first 5 years of life
- By 40s, patients may develop symptoms
- Small ASDs < 5 mm in diameter may not generate symptoms
- 5-10 mm defects lead to symptoms in 4th and 5th decade of life
- > 10 mm defects present with symptoms in 3rd decade
- LV stiffness increases as a part of normal aging, impairing left heart diastolic filling
- Increases left to right shunt across ASD
- Produces RA and RV volume overload
- May predispose to paradoxical embolus, causing stroke, TIA, acute limb ischemia, mesenteric ischemia, etc.
- Right to left shunt may occur during coughing, for example
- Pulmonary hypertension produces this shunting pattern even at rest
- Unlike ventricular septal defects, uncomplicated ASDs are not associated with high risk of bacterial endocarditis (lower turbulence and velocity of blood flow)
A patient may be asymptomatic or have any of the following features:
Congenital Heart Disease Types
- Differentiation by pulmonary vascularity on CXR
- An ECG may show the “crochetage” pattern (92% specific)—a notch near the apex of the R wave in inferior limb leads
- Large notches signify a larger shunt
- Other ECG findings
- (Incomplete right bundle branch block, very sensitive
- Subcostal view preferred window, due to interatrial septum perpendicular to echo signal (apical four-chamber is parallel to ASD echo signal)
- Clues to ASD
- Hypermobile interatrial septum
- Abrupt septal irregularity
- RA and/or RV volume overload
- Pulmonary artery dilation
- High pulmonary artery pressures
- TTE with Doppler can demonstrate most shunting
- Agitated saline with Valsalva maneuver to increase right to left shunting is more diagnostic
- Medical management of complications (Afib, pulmonary HTN, etc.)
- Avoid pregnancy and exertional activity in ASD complicated by pulmonary hypertension
- Indications for ASD closure
- Right heart overload with RA or RV enlargement
- Complicated ASDs
- If no acute complications → discharge with outpatient follow-up
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