A middle aged lady was diagnosed to incidentally have a ejection systolic murmur at the pulmonary area. A fixed wide split of the second heart sound was also noted. The diagnosis is:-

Classically presents as an asymptomatic patient with a flow murmur in the pulmonary area and a fixed  wide split of S2. Atrial septal defects occur most commonly in the region of the fossa ovalis, referred to as secundum-type defects .Additional atrial  septal  defects  include  defects  of  the  sinus  venosus  and  atrium primum. Color flow Doppler echocardiography is usually sufficient for diagnosis of a secundum-type atrial septal defect, but agitated saline is generally needed for the diagnosis of other types of atrial septal defects.