Cardiac catheterization is a procedure used to diagnose and treat cardiovascular conditions. During cardiac catheterization, a long thin tube called a catheter is inserted in an artery or vein in your groin, neck or arm and threaded through your blood vessels to your heart. The catheter will deliver dye that will show up on an X-ray to visualize the coronary arteries.   This is one of the most accurate tests performed to detect the presence of coronary artery disease or blockages. It also helps to indicate which arteries have been narrowed by atherosclerosis.  This will help your cardiologist and family doctor determine the best course of action to be taken.