Pulmonary blood flow and RA and RV volume are increased. (NOTE: Intracardiac pressures generally remain in the normal range throughout childhood.) With a large defect, RA and LA pressures are equal.

AO = aorta; IVC = inferior vena cava; LA = left atrium; LV = left ventricle; PA = pulmonary artery; PV = pulmonary veins; RA = right atrium; RV = right ventricle; SVC = superior vena cava.