Heart bypass surgery. Image 6 of 18. Part of a magnet system being attached to a healthy artery before it is attached to a diseased coronary artery in coronary artery bypass graft (CABG) surgery. This re-routes the blood flow, bypassing the blocked coronary artery. The artery will be attached using this magnetic vascular positioner system, which is faster and less invasive than hand-sewing. Blood vessels can become blocked by the build-up of fatty plaques (atherosclerosis). This reduces blood flow to the areas served by the vessel. Inadequate blood flow to the heart can lead to heart pain (angina) or a heart attack (myocardial infarction). For a sequence showing the operation see M560/564-M560/581.