It is a congenital defect in the septum between two atria.

Common in females M:F = 1:2.


There are 2 types of Atrial Septal Defect (ASD)

1. Ostium primum (15% cases)—results from atrioventricular defect in septum.
2. Ostium secundum (75% cases)—defect mainly at the fossa ovalis in the atrial mid septum.

Clinical Features


• May be asymptomatic.
• Breathlessness on exertion.
• Palpitation, weakness.


In precordium
• First heart sound is normal.
• Wide and fixed splitting of 2nd heart sound.
• An ejection systolic murmur in left 2nd and 3rd intercostal space.
• There is also a high-pitched MDM in tricuspid area.
NB: When there is reversal of shunt, features of Eisenmenger’s syndrome will be found.


• X ray chest—shows cardiomegaly.
• ECG.
• 2D echocardiography and colour Doppler.
• Cardiac catheterisation in some cases.
• MRI (or CMR) may be helpful.
ECG finding in ASD
• In primum type—RBBB with left-axis deviation.
• In secundum type—RBBB with right-axis deviation.

Complications of ASD

• Pulmonary hypertension with reversal of shunt (Eisenmenger’s
• Arrhythmia—atrial fibrillation (most common).
• Embolism (pulmonary and systemic) and brain abscess.


• Small ASD—Surgery is not needed, only follow-up.
• Moderate to large—Surgical closure.
• Angiographic closure is possible with transcatheter clamshell device.
• If Eisenmenger’s syndrome develops—surgical closer is contraindicated (see in Eisenmenger’s


MDM: Mid diastolic Murmum