Coronary artery bypass graft (CABG) operations are one of the most commonly performed surgical procedures, with a worldwide prevalence of over 800,000 annually and more than 350,000 operations being performed in the United States each year.

The use of the left internal mammary artery (LIMA) is widely considered to be the gold standard for conventional CABG operations. Its use has been shown to result in a lower incidence of re-intervention, fewer myocardial infarctions, lower incidence of angina, and lower associated mortality rates than with the use of saphenous vein grafts alone. Also when compared to saphenous vein grafts, LIMA use has been shown to have greater longterm patency results.

For patients with multivessel coronary disease undergoing what is usually referred to as conventional CABG, the LIMA is typically grafted to the left anterior descending (LAD) artery with saphenous vein grafts often used to bypass the remaining coronary occlusions. 

However, arterial conduits are now being more frequently used as choices for the second and third conduits in place of saphenous vein grafts to achieve total arterial revascularisation ( TAR) of the myocardium due to superior patency and long-term survival results. This article provides a review of TAR using the right internal mammary artery (RIMA) and with the LIMA as a first choice conduit. The reported benefits of TAR when compared to conventional CABG procedures using the LIMA and saphenous vein grafts are discussed.

LIMA use in CABG at CARE Hospitals, Bhubaneswar: The LIMA is widely considered to be the best conduit for CABG procedures. In a study of the Society of Thoracic Surgeons National Cardiac Database performed by Tabata et al., data from 541,368 CABG surgeries taking place between 2002 and 2005 were analyzed. Among all procedures performed, 92.4 per cent of patients had at least one IMA graft, and the frequency of LIMA usage by each hospital ranged from 48.0% to 100% with a median of 94 per cent.

The presence of an IMA graft has also been identified as an independent predictor of survival and confers significantly better long-term survival rates than the use of saphenous vein grafts alone. While anatomically identical to the LIMA, the RIMA is rarely used in CABG procedures, and is almost always used as part of bilateral internal mammary artery (BIMA) grafts when it is utilized. Outcomes of BIMA in CABG: Despite its low prevalence of use, many studies have shown that RIMA use in conjunction with the LIMA can confer significantly better clinical outcomes when compared to conventional CABG procedures with the LIMA and saphenous vein grafts.

Survival benefits of BIMA versus Single Internal Mammary Artery (SIMA): Several observational, retrospective studies have found that there are significantly greater long-term survival benefits in patients who received BIMA grafting compared to SIMA grafting.

Lytle et al. studied 10,124 elective CABG patients receiving either SIMA or BIMA grafts with or without any additional vein grafts in a retrospective, non-randomized study with a mean follow-up of 10 post-operative years.

(The writer is MS, Mch, and chief CTVS Surgeon, CARE Hospitals, Prachi Enclave, Bhubaneswar)