Atrial Septal Defect Characteristics

Pathophysiological Basis

The left-to-right shunt across the atrial septal defect causes increased blood flow through the right side of the heart, leading to right ventricular volume overload and pulmonary overcirculation, as stated by the American Heart Association 1, 2
This increased flow creates a relative disproportion between the tricuspid valve orifice size and the diastolic blood flow volume, affecting valve closure dynamics, according to clinical guidelines 3

On auscultation, atrial septal defect typically presents with a fixed splitting of the second heart sound and a systolic pulmonary flow murmur, as recommended by the American College of Cardiology 1
With large shunts, a diastolic flow rumble across the tricuspid valve may also be present due to increased flow, as noted by the American Heart Association 1
The mid-diastolic murmur heard in atrial septal defect is a right-sided finding that typically increases with inspiration, as stated by the American College of Cardiology 3

Patients with unexplained right ventricular volume overload should be referred to an Adult Congenital Heart Disease center for further diagnostic studies, as recommended by the American Heart Association 4
The characteristic loud first heart sound with accentuated tricuspid component can be a helpful diagnostic clue in identifying atrial septal defect, and should prompt further evaluation with imaging techniques to demonstrate shunting across the defect and evidence of right ventricular volume overload, according to the American College of Cardiology 4

The intensity of heart sounds and murmurs in atrial septal defect may change during pregnancy due to increased cardiac output, as noted by the American College of Cardiology 2
In older patients with atrial septal defect, the development of pulmonary hypertension may alter the auscultatory findings, as stated by the American Heart Association 2