ELECTROCARDIOGRAPH. Doctors also use a method called radionuclide imaging to detect CAD. In this procedure, a doctor injects a radioactive element into a patient's bloodstream. The doctor can view the element on a screen as it spreads into the heart muscle. Areas that do not receive blood appear blank on the image. Doctors generally use radionuclide imaging with a stress ECG.

A type of computed tomography (CT), commonly called a heart scan, is sometimes used to detect calcium deposits in coronary arteries. Such calcium deposits may indicate a risk for heart disease in some people.

If these diagnostic techniques leave doubt about the presence of CAD, physicians may perform cardiac catheterization followed by coronary angiography. In these tests, doctors insert a long, flexible tube called a catheter through a large blood vessel, usually an artery in the area where the thigh and abdomen meet. They push the catheter up to the beginning of the coronary arteries, then inject a special dye. The dye clearly shows the condition of the arteries as it travels through them. An image of the arteries can be recorded on an X-ray film called an angiogram. Doctors perform angiography only when diagnosis is difficult, because it carries a small risk of injury or death.