Atrial septostomy.
D006328:Cardiac Catheterization; D002675:Child, Preschool; D006325:Heart Atria / Q000601:surgery*; D006346:Heart Septum / Q000601:surgery*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D014188:Transposition of Great Vessels / Q000601:surgery*