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Pathology

Abnormal connection between the left and right atrium
There are two main types of ASD:
Ostium secundum (80%): defect in centre of atrial septum (foramen ovale)
Ostium primum (10%): defect in lower atrial septum (involving AV valve)

Aetiology

Congenital, more common in female. Down syndrome is associated with ostium 
primum

Signs

Soft systolic murmur, upper left sternal edge, fixed splitting of 2nd heart sound, 
left parasternal heave, clubbing 

Symptoms

Usually asymptomatic until adult hood
Heart failure (poor feeding, failure to thrive, tachypnoea, sweating, vomiting) or 
palpations and recurrent chest infections 

Investigations

ECG: Ostium primum – Left axis deviation
Ostium secundum - right axis deviation, right bundle branch block
Chest X-Ray: Cardiomegaly and increased pulmonary vasculature 
Echo: Assesses heart structure and confirms defect

Treatment

Conservative Management: Small defects with minima, shunting can be 
monitored
Surgical: Closure at 4-5 years of age

Prognosis

90% close achieved by insertion of an occlusion device in the catheter laboratory
Prognosis is good once defects corrected however development of Eisenmenger Syndrome is a life threatening complication
If surgical correction is not undertaken, heart failure or arrhythmias may occur
Eisenmenger Syndrome (reversal of left to right shunt resulting in cyanosis) 

Key Facts

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Key Images

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Key References

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