MODEL RELEASED: Cath Lab. View of a monitoring room of a cardiac catheterisation laboratory ('Cath Lab'). A technician uses X-rays to monitor the catheterisation procedure on a screen, and records the images obtained photographically and on digital tape. Through the window may be seen surgeons performing the procedure. A thin, hollow tube (catheter) is inserted into a blood vessel, normally in the thigh. The catheter is then guided to the heart. Once in place, a radio-opaque dye may be injected into the patient. This may reveal various heart problems, the most common of which would be occlusion of the coronary arteries - a cause of myocardial infarction (heart attack).