A Coronary Angiogram is a special X-ray test performed to find out if your coronary arteries are clogged, where and by how much. During an angiogram, your doctor inserts a thin tube (catheter) into an artery and up to the heart. Once in place, a dye that is visible by X-rays (contrast dye) is injected into the bloodstream. The X-ray machine takes a series of images (angiograms) which will show any areas of narrowing. This procedure is done as part of the cardiac catheterization procedure.