Tips on ASD

-As a rule, an ASD must be at least 10 mm in diameter to carry a significant left-to-right shunt.
• CAVEAT: symptoms may develop with increasing age even with small defects owing to an increase in shunting caused by a decrease in LV compliance secondary to coronary artery disease, acquired valvular disease, or hypertension

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-Although small ASDs of <5 mm and no evidence of RV volume overload do not impact the natural history of the individual and thus may not require closure because :
–Paradoxical embolism may occur
–Some small defects however may have progressive increase in left-to-right shunt depending on LV and LA pressures.

-Magnitude of and direction of flow depends on –Size of the defect
–Relative diastolic filling properties of the left and right ventricles.
• Increased left-to-right shunting results from reduced LV compliance (eg, LVH) and mitral stenosis.
• Reduced left-to-right shunt and/or reversal of shunt (rightto-left shunt) results from reduced RV compliance (eg, pulmonary hypertension or pulmonary stenosis) and tricuspid stenosis.

-Definite and Potential Benefits of ASD Closure :
•RV and RA size ↓
•LV size ↑
•PA pressure ↓
•Right-to-left shunting and embolism ↓
•Exercise capacity ↑
•NYHA class ↓
•Atrial arrhythmias ↓