A flexible tube with a collapsible blade at the distal end that, once in situ, can be raised to an acute angle by the surgeon operating an actuation lever at the proximal end for a blade atrial septostomy (BAS) procedure. It is used to enlarge the interatrial opening in cases of mitral atresia (a septal defect found in the hearts of infants) or unsuccessful or insufficient balloon atrial septostomy. This procedure allows interatrial blood mixing in infants with congenital cardiac malformations. It is typically made of plastic and high-grade stainless steel materials. This is a single-use device.