Balloon septostomy is the widening of a foramen ovale

Foramen ovale

There are multiple structures in the human body with the name foramen ovale :* In the fetal heart, the foramen ovale is a shunt from the right atrium to left atrium....

, patent foramen ovale (PFO), or atrial septal defect

Atrial septal defect

Atrial septal defect is a form of congenital heart defect that enables blood flow between the left and right atria via the interatrial septum. The interatrial septum is the tissue that divides the right and left atria...

 (ASD) via cardiac catheterization

Cardiac catheterization

Cardiac catheterization is the insertion of a catheter into a chamber or vessel of the heart. This is done for both investigational and interventional purposes...

 (heart cath) using a balloon catheter

Balloon catheter

A balloon catheter is a type of "soft" catheter with an inflatable "balloon" at its tip which is used during a catheterization procedure to enlarge a narrow opening or passage within the body...

. This procedure allows a greater amount of oxygen

Oxygen

Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

ated blood

Blood

Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

 to enter the systemic circulation

Systemic circulation

Systemic circulation is the part of the cardiovascular system which carries oxygenated blood away from the heart to the body, and returns deoxygenated blood back to the heart. This physiologic theory of circulation was first described by William Harvey...

 in some cases of cyanotic

Cyanotic heart defect

A cyanotic heart defect is a group-type of congenital heart defects . The patient appears blue , due to deoxygenated blood bypassing the lungs and entering the systemic circulation...

 congenital heart defect

Congenital heart defect

A congenital heart defect is a defect in the structure of the heart and great vessels which is present at birth. Many types of heart defects exist, most of which either obstruct blood flow in the heart or vessels near it, or cause blood to flow through the heart in an abnormal pattern. Other...

 (CHD).

After the catheter is inserted, the deflated balloon catheter is passed from the right atrium

Right atrium

The right atrium is one of four chambers in the hearts of mammals and archosaurs...

 through the foramen ovale, PFO or ASD into the left atrium, it is then inflated

Inflatable

An inflatable is an object that can be inflated with a gas, usually with air, but hydrogen, helium and nitrogen are also used. One of several advantages of an inflatable is that it can be stored in a small space when not inflated, since inflatables depend on the presence of a gas to maintain their...

 and pulled back through to the right atrium, thereby enlarging the opening and allowing greater amounts of blood to pass through it. The resulting man-made opening is one of many forms of shunting

Shunt (medical)

In medicine, a shunt is a hole or a small passage which moves, or allows movement of fluid from one part of the body to another. The term may describe either congenital or acquired shunts; and acquired shunts may be either biological or mechanical.* Cardiac shunts may be described as...

, and is often referred to as an ASD.

This is normally a palliative procedure used to prepare a patient for, or sustain them until, a corrective surgery can be performed. At this time the ASD is closed using either sutures or a cardiac patch, depending on the size and/or nature of the opening.