Laser heart surgery. Laser being used during open heart surgery. Several small holes can be seen in the damaged (dark) section of heart muscle. A red point of laser light is seen below the emitter. This is a technique known as transmyocardial laser revascularisation (TMR). It is done to remedy angina pectoris, chest pain caused by a lack of a normal blood supply to the heart muscle. The laser makes several small holes in the starved heart muscle, allowing direct flow of oxygenated blood. Angina pectoris is caused by fatty deposits building up on the interior walls of the coronary arteries. If left untreated, part of the heart mu- scle may die (a heart attack), which may be fatal.