MODEL RELEASED. Coronary angiography. Surgeon inserting a guide catheter into an artery in the arm of a 50-year-old man in a coronary angiography examination. This procedure is used to examine a patient's coronary arteries by passing the main catheter (a long thin wire) through the guide catheter and along the patient's arteries to a position close to the heart. A contrast medium is then injected to highlight the coronary arteries on an X-ray. If problems such as narrowed arteries due to coronary artery disease are discovered, then the same procedure can be used to carry out a coronary angioplasty treatment to widen the artery and prevent a heart attack. Photographed at the American Hospital of Paris, France.