A therapeutic cardiac catheterization is a procedure performed to treat your child's heart defect. A doctor will use special techniques and a thin plastic spaghetti-like tube or catheter that goes to the heart from blood vessels in the legs or the neck. These techniques allow the repair to be done without surgically opening the chest and heart. The types of defects that can be repaired include closing a hole in the wall that separates the heart's right and left sides, widening a narrowed vessel or stiff valve, and closing abnormal blood vessels using a variety of devices.