Atrial Septal Defect (ASD) Hole in interatrial septum Allow left atrial blood atrium (oxygenated to enter right Atrial septal atrium(lower pressure defect Increased work load of right Right ventricle atrium Small hole no significant effect Mixing blood from left (oxygenated Medium or large hole may and right (deoxygenated) atria require surgical repairAtrial Septal Defect (ASD) • Hole in interatrial septum • Allow left atrial blood (oxygenated) to enter right atrium (lower pressure) • Increased work load of right ventricle • Small hole, no significant effect • Medium or large hole may require surgical repair