Procedure
The majority of atrial septostomies are performed on infants with d-TGA or other cyanotic heart defects. In these cases, a balloon catheter is guided through a large vein into the right atrium, during cardiac catheterization. The catheter is threaded into the foramen ovale, a naturally-existing hole between the atria that normally closes shortly after birth. The balloon at the end of the catheter is inflated so as to enlarge the foramen ovale enough that it will no longer become sealed. This allows more oxygenated blood to enter the right heart (especially in the case of d-TGA) where it can be pumped to the rest of the body. The balloon is deflated and the catheter is removed.
Sometimes the initial surgery is not entirely successful, or there are other factors that make a simple balloon atrial septostomy impossible, such as an older patient whose foramen ovale has already closed. This is when a blade atrial septostomy is performed. The details of the procedure are largely the same, except that a small blade on the end of the catheter is first used to create an opening between the right and left atria, before the insertion of the balloon.
Read more about this topic: Atrial Septostomy