Then the cannulas and the catheter are placed, cardiopulmonary bypass is commenced (venous deoxygenated blood arriving to the heart is forwarded to the CBP machine to get oxygenated and delivered to aorta to keep rest of the body saturated, and often cooled to 32 - 34 degrees celsius in order to slow down the metabolism and minimize as much as possible the demand for oxygen. A clamp is placed on the Aorta between the cardioplegic catheter and aortic cannula, so the cardioplegic solution that the flow is controlled by the surgeon that clamps Aorta. Within minutes, heart stops beating. Anastomosis (grafting)With the heart still, the tip of the heart is taken out of pericardium, so the native arteries lying in the posterior side of the heart are accessible. Usually, distal anastomosis are constructed first (first to right coronary system, then to the circumflex) and then the sequential anastomosis if necessary. Surgeons check the anastomosis for patency or leaking and if everything is as it should be, surgeons insert the graft within the pericardium, sometimes attached to the cardioplegic catheter. The anastomosis of LIMA to LAD is usually the last one of the distal anastomoses to be constructed, while it is being constructed the rewarming process starts (by the CPB).. After the anastomosis is completed and checked for leaks, the proximal anastomoses of the conduits, if any, are next.
Which one is preferable for each patient is still a matter of debate, but it is clear that in the presence of complex lesions,  significant Left Main Disease and in diabetic patients, CABG seems to offer better results to patients than PCI. Strong indications for CABG also include symptomatic patients and in cases where LV function is impaired., CABG offers better results that PCI in left main disease and in multivessel CAD, because of the protection arterial conduits offer to the native arteries of the heart, by producing vasodilator factors and preventing advancement of atherotic plaques. The question which modality has been studied in various trials. Patients with unprotected LM Disease (runoff of LM is not protected by a patent graft since previous CABG operation) were studied in NOBLE and EXCEL trials. NOBLE, which was published in 2016 is a multi-European country that found that CABG outperforms PCI in the long run (5 years). EXCEL, also published in 2016, found that PCI has similar results to CABG at 3 years, but this similarity fades at 4th year and later (CABG is better to PCI).Diabetic patients were studied in the FREEDOM trial, first published in 2012 and a follow up. It demonstrated a significant advantage in this group of patients when treated with CABG (vs PCI). The superiority was evident in a 3.8 year follow up and, an even further followup at 7.5 years, of the same patients documented again the superiority of CABG, enphasazing the benefits in smokers and younger patients.