ICE correctly detected 4/40 cases (10%) multiple - hole ASD that were missed by transthoracic echocardiography (TTE) or transesophageal echocardiography (TEE); help accurately identify atrial septal defect anatomy, the number of ASD holes and the proper technique to close ASD (1 case using ASO Cribiform device closure of many fenestrated holes, 3 cases of two - hole ASD using a larger ASO device to close both holes).