A nonrestrictive interatrial communication is mandatory in some patients with complex cyanotic heart disease. Up to the present time, Park blade atrial septostomy with a Park blade catheter is performed only under fluoroscopic guidance. We successfully monitored only under transthoracic 2-dimensional (2D) echocardiography (TTE), in a 7-week-old infant with d-Transposition of Great Arteries (d-TGA), a restrictive patent foramen ovale (PFO), and small ventricular septal defect (VSD), who presented with severe hypoxemia. TTE confirmed the position of the blade before and during pullback to the right atrium, followed by balloon septoplasty. There was an adequate enlargement of the interatrial communication with subsequent improvement in the oxygenation of the infant. This is the first reported case of the performance of blade atrial septostomy as a bedside TTE guided procedure here in the Philippines.