A young female presents with history of dyspnoea on exeion. On examination, she has wide, fixed split S. with ejection systolic murmur (TJIAT) in left second Intercostal space. Her EKGshows left axil detion. The most probable diagnosis Is -

Examination Usually reveals a prominent RV impulse and palpable pulmonary aery pulsation. Midsystolic pulmonary outflow murmur. The second hea sound is widely split and is relatively fixed in relation to respiration. A mid-diastolic rumbling murmur, loudest at the fouh intercostal space and along the left sternal border Electrocardiogram In ostium primum ASD, the RV conduction defect is accompanied by left superior axis detion and counterclockwise rotation of the frontal plane QRS loop. Varying degrees of RV and right atrial (RA) enlargement or hyperophy may occur (Harrison's Principles of internal medicine, 18 th edition, page 1922 )