Heart bypass surgery. Surgeon wearing a headlamp and camera whilst performing coronary artery bypass graft (CABG) surgery. During CABG, a healthy artery is attached to the diseased coronary artery in order to re-route the blood flow, bypassing the blocked coronary artery. This is usually to treat atherosclerosis, a build-up of fatty deposits that can lead to heart pain (angina) or a heart attack (myocardial infarction).