A coronary angiogram is a procedure that uses X-ray imaging to see the inside of your heart`s blood vessels.Coronary angiograms are part of a general group of procedures known as cardiac catheterization. Catheterization refers to any procedure in which a long, thin, flexible plastic tube (catheter) is inserted into your body. Heart catheter procedures can both diagnose and treat heart and blood vessel conditions. A coronary angiogram, which can help diagnose heart conditions, is the most common type of heart catheter procedure. During a coronary angiogram, a type of dye that`s visible by X-ray machine is injected into the blood vessels of your heart. The X-ray machine rapidly takes a series of images (angiograms), offering a detailed look at the inside of your blood vessels. If necessary, your doctor can perform procedures such as angioplasty during your coronary angiogram.