In the apical / subcostal 4-chamber positions the dominance of the right chambers of the heart is seen, the defect is predominantly of the middle third of the IAS(interatrial septum) of 8-16 mm with a T-shaped margin(atrial septum defect - ASD - ostium secundum).
At the CFM: the indicated defect is stained in the direction from the LA(left atrium) to the RA(right atrium).
