Close-up of the terminal part of a catheter provided with an argon laser, used for treating narrowing or blockage of blood vessels. This operation is known as angioplasty and the laser technique is especially used to remove atheroma (fatty deposits) from the arterial walls. The catheter carries two bundles of optic fibers: one is used to transmit the laser beam whereas the other one enables the accurate positioning of the laser beam onto the target. The arterial plaque is vaporized by the laser; the main danger is of accidentally burning a hole in the arterial wall.