The surgeon will make the incision and then split the sternum, or breastbone, with a vibrating saw. If this is a bypass operation, assistants will now begin harvesting vein grafts from your lower leg, which will be used to bypass the blocked arteries in the heart. Anti-coagulants will be then be introduced into your blood so that it can no longer clot, and you'll be connected to a cardiopulmonary bypass ma chin e, also called the heart pump. This ma chin e takes over your lung and heart functions - your blood is drawn into the ma chin e where it is cleansed and nourished before being fed back into your body.

Your body temperature will be dropped to 28 - 32°C, which slows your heartbeat almost to a stop, and the aorta is clamped to stop it completely, so the heart is soft and quiet to allow the surgeons to work on it.

From here on the procedure varies for bypass or valve replacement surgery.