A parent or legal guardian will need to sign a consent form that authorizes the procedure. Immediately before the procedure, the infant may need to be restrained for his or her own safety because too much movement during the procedure could complicate the process or injure the infant. Parents should be prepared to see their infant crying and resisting the procedure.

The balloon atrial septostomy is a catheter-based procedure. During the procedure, the area where the catheter is to be inserted is first numbed with a local anesthetic. The physician will then make a cut (incision) at that area. Guided by images created by a fluoroscope (a type of real-time x-ray), the physician inserts the catheter through the blood vessel and guides it all the way up to the atrial septal defect in the left atrium. A balloon at the tip of the catheter is then inflated to a diameter of about 15 millimeters and then pulled through the ASD and into the right atrium. The catheter is then withdrawn and the procedure is complete.

With the septal hole now enlarged, the infant’s cyanosis should be partially relieved, and the patient should be able to receive enough oxygen until surgical repair of the other congenital heart defects. The enlarged atrial septal defect will also be closed when it is no longer necessary.