Last updated on: January 25th, 2023

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Atrial septal defect

Clinicals - History

No symptoms

Small atrial septal defects (ASD) (i.e., <5 mm in diameter) are generally asymptomatic during childhood—and possibly for the entire lifespan of the affected person. Even large ASDs (i.e., >10 mm in diameter) may be asymptomatic in childhood, only producing symptoms after the third decade of life.

Frequent respiratory infections

Infants with large ASDs may present with frequent respiratory infections. This is due to the increase in pulmonary blood flow secondary to left-to-right shunting.


In infants this may manifest as a difficulty in feeding; this is due to increased fatigability. Older children may complain of exertional dyspnea. In some cases, dyspnea may be the only clue to underlying heart failure. Dyspnea occurs due to the abnormal increase in pulmonary blood flow secondary to left-to-right shunting.


Palpitations secondary to arrhythmias mainly occur in adults; but can occur in children.


Rarely, cyanosis may occur if shunt reversal occurs. Shunt reversal occurs in severe pulmonary hypertension, when pressures of the right heart exceed those of the left heart.

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