Left internal mammary artery (LIMA): It is most often used for bypassing left anterior descending (LAD) coronary artery and its diagonal branch. The right internal mammary artery (RIMA) is used for bypassing right coronary artery (RCA) or its posterior descending branch (PDA). IMA can be used as in silu graft without disconnecting it from the subclavian artery, It can also be used as a free graft between aorta and the coronay artery. For total arterial revascularisation (TAR) using mammary arteries, free RIMA end is anastomosed to the side of LIMA as Y or T graft. The LIMA is then used for bypassing diagonal and LAD branches. RIMA is then taken around the heart for side-to-side anastomosed with obtuse marginal branches (OM) and its end is anastomosed to PDA, thereby achieving total arterial re-vascularisation (TAR). In the place of RIMA a radial artery graft can be used the same way for total arterial re-vasculru-isation (TAR).

Figure: Coronary artery bypasses grafting -Total arterial re-vuscularisution

The internal mammary artery is harvested as a pedicle with its venae comitantes, nerve bundles and parts of inter costal muscles. It can also be skeletonised leaving only the artery. The entire branches arc clipped with haemoclips.

After median sternotomy a special retmotor is used to raise the sternal edge and the mammary artery is harvested. At the upper end, care is taken not to injure phrenic nerve and subclavian vein while dissection is being done with electro cautery. The artery is sprayed with papavcrine solution (2 mmol/litre). The distal end is divided and flow checked. The conduit is covered with gauze soaked in papaverine solution.