Laser heart surgery. Surgeon's hand creating holes in a patient's heart muscle with an excimer laser probe. This procedure is known as transmyocardial revascularisation (TMR). The small holes increase the amount of blood reaching parts of the muscle that are supplied by narrowed or blocked coronary arteries. If an area of heart muscle does not get enough oxygen it will die, resulting in a heart attack. A coronary artery bypass has also been carried out. During this procedure, narrowed or blocked coronary arteries were bypassed by vein grafts from the legs.