During a heart catheterization for congenital heart defects, a small tube (catheter) is threaded through a blood vessel in the groin or sometimes in the neck. The catheter moves through the blood vessel into the heart. Some procedures to correct congenital heart defects can be done during a heart catheterization. These include:

• Septostomy. For a septostomy, an opening is made in the wall of the heart between the upper chambers to allow blood to mix between the heart chambers. This procedure is generally used to treat transposition of the great vessels, tricuspid atresia, and hypoplastic left heart syndrome. It does not correct the congenital heart defect but allows oxygen-rich blood to get out to the body until surgery can be done to correct the defect.
• Closing a defect. During a heart catheterization, doctors may use a device called a septal occluder or coil to close an atrial septal defect, ventricular septal defect, or patent ductus arteriosus.
• Valvulotomy. For a valvulotomy, a small balloon is inflated in a heart valve, widening the heart valve. This procedure can be used to treat pulmonary valve stenosis and aortic valve stenosis.
• Balloon angioplasty. A balloon is inflated in an artery to widen the artery. This procedure can be used to treat coarctation of the aorta.
• Stents. Small wire-mesh coils (stents) can be placed in arteries to hold them open. Stents for treatment of congenital heart defects are often placed in arteries outside the heart, such as the pulmonary arteries or aorta.