Infant receiving anaesthetic gas through a mask prior to a cardiac catheterization procedure, a technique used to assess congenital heart defects. Under general anaesthetic, a catheter (a small tube) is inserted into an artery in the groin & guided by X-ray imaging into a coronary artery. Once in place an iodine-based dye is injected to outline the arterial blood flow on X-ray film. The technique is used in adults to image blood flow in the coronary arteries & diagnose coronary artery disease, where the arteries are obstructed by the formation of fatty atheroma plaques.