This is a procedure done on the heart. 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 percutaneous transluminal coronary intervention (PCI). Catheterization is also done on infants and children to examine or treat congenital (kon-JEN'ih-tal) heart defects.
Sometimes a special dye is put into the catheter to make the insides of your heart and blood vessels show up on x rays. The dye can show whether a material called plaque (plak) has narrowed or blocked any of your heart’s arteries (called coronary arteries).
Plaque is made up of fat, cholesterol, calcium, and other substances found in your blood. The buildup of plaque narrows the inside of the arteries and, in time, may restrict blood flow to your heart. When this happens, it’s called coronary artery disease (CAD).