What is cardiac catheterization? 

This is a procedure to examine blood flow to the heart and test how well the heart is pumping. A doctor inserts a thin plastic tube (catheter) (KATH'eh-ter) into an artery or vein in the arm or leg. From there it can be advanced into the chambers of the heart or into the coronary arteries.

This test can measure blood pressure within the heart and how much oxygen is in the blood. It's also used to get information about the pumping ability of the heart muscle. Catheters are also used to inject dye into the coronary arteries. This is called coronary angiography (an"je-OG'rah-fe) or coronary arteriography (ar-te"re-OG'rah-fe). Catheters with a balloon on the tip are used in the procedure called coronary angioplasty (commonly referred to as percutaneous coronary intervention [PCI]). Catheterization of the heart may also be done on infants and children to examine for congenital (kon-JEN'ih-tal) heart defects.