Coronary artery angiogram. Computerenhanced coloured Xray angiogram of coronary blood vessels (pinkblue) that feed the muscle of the heart. The left coronary artery and its branches are seen here. They follow the rounded shape of the heart (red). In the background, ribs (green) of the ribcage are visible. An angiogram is made by injecting the blood vessels of the patient with an Xray opaque substance and then taking an X ray. Blood vessels show up clearly, allowing conditions such as coronary artery disease (where the coronary artery narrows) to be identified. Blockages in the artery that lead to heart attack can also be identified.