It is a type of cardiac catheterization procedure. It is performed for both interventional and diagnostic purposes. In this procedure, a dye that is radiopaque is injected into the blood vessels of one’s heart. An X-ray machine is then used to take serial images (angiograms) that give a picture of how the blood vessels are. Based on the finding, an interventional cardiologist will open the clogged vessels (angioplasty).