8th March 2024

Clinical presentation

Patients commonly remain asymptomatic until adulthood, where 30% begin to develop breathlessness on exertion by the third decade and more than 75% of patients by the fifth decade. Late complications include supraventricular tachyarrhythmias, severe pulmonary hypertension and right-sided heart failure. Paradoxical embolism causing systemic events may be the first clue to an ASD. 

Auscultation will reveal fixed splitting of S2 and a systolic flow murmur at the left second intercostal space. A loud P2 component of the second heart sound indicates pulmonary hypertension. If cyanosis develops, this generally suggests reversal of the shunt (Eisenmenger syndrome).