Atrial septostomy is a surgical procedure in which a small hole is created between the upper two chambers of the heart, the atria.

[1] The first atrial septostomy (then less precisely called a septectomy) was developed by Vivien Thomas in a canine model and performed in humans by Alfred Blalock.

The catheter is threaded into the foramen ovale, a naturally existing hole between the atria that normally closes shortly after birth.

[citation needed] 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.

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.

The Rashkind balloon atrial septostomy is performed during cardiac catheterization (heart cath), in which a balloon catheter is used to enlarge a foramen ovale, patent foramen ovale (PFO), or atrial septal defect (ASD) in order to increase oxygen saturation in patients with cyanotic congenital heart defects (CHDs).