Laser heart surgery. Surgeon's gloved hand using a laser to operate during open heart surgery. This technique is known as transmyocardial laser revas- cularisation (TMR). It is done to remedy coronary artery diseases such as angina pectoris, chest pain caused by a lack of a normal blood supply to the heart muscle. The laser is used to make several small holes in heart muscle, allowing oxygenated blood to flow directly to the starved area. Angina pectoris is caused by atheroma plaques (fatty deposits) on the interior walls of the coronary arteries. If left untreated, part of the heart muscle may die (a heart attack), which is often fatal.