False-colour angiogram (arteriogram) of an adult human heart revealing multiple stenoses (obstructions) in the left coronary artery (LCA). The image was made following treatment of coronary artery disease (CAD) using percutaneous transluminal coronary angioplasty - PTCA or balloon angioplasty". Coronary artery angiography is an X-ray technique in which a radio-opaque dye is injected via a catheter to outline the arteries which supply the heart. Here, the red trace of the LCA (running top centre to left) appears pinched at various points along its length, due to the build-up of fatty, atheroma plaques."