Figure 1: (a) Electrocardiogram revealed right bundle branch block pattern with left anterior hemiblock. (b) Chest X-ray was suggestive of cardiomegaly with pulmonary plethora and prominent proximal pulmonary arteries. (c) Two-dimensional echocardiography demonstrated a humungous 76 mm ostium secundum atrial septal defect. (d) Ostium secundum atrial septal defect with left-to-right shunt. (e) Pulmonary artery systolic pressure of 77 mm of Hg + right atrial pressure indicating severe pulmonary artery hypertension. (f) Moderate-to-severe mitral regurgitation