We describe a patient with severe pulmonary artery hypertension and refractory right heart failure who underwent "butterfly" stent atrial septostomy guided by intracardiac ultrasound. This technique may be superior to previously reported blade and balloon septostomy because it allows creation of an atrial septal defect of a precise predetermined diameter. The patient's systemic blood flow and clinical status improved significantly after the procedure, allowing her to be accepted as a candidate for lung transplantation.