Angiogram is an X-ray diagnostic procedure used to visualize the blood vessels following injection of a contrast substance into an artery. It is used to image arteries in the brain, heart, kidneys, gastrointestinal tract, aorta, neck (carotids), chest, limbs and pulmonary circuit. Coronary angiography is performed to detect obstruction in the coronary arteries, which can lead to heart attack. It may be performed if you have unstable angina, a typical chest pain, aortic stenosis, or unexplained heart failure.