Laser heart surgery. Surgical team using a laser (down centre) during open heart surgery. A red point of laser light is seen by one surgeon's hand at lower centre. 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 area of heart muscle, which allow a direct flow of oxygenated blood. Angina is caused by fatty deposits building up inside the coronary arteries. If untreated, part of the heart muscle may die (a heart attack), which is often fatal.