Anatomical Location of the Left Internal Mammary Artery (LIMA)
The Left Internal Mammary Artery (LIMA), also known as the left internal thoracic artery, is a branch of the left subclavian artery that runs along the inner surface of the anterior chest wall, approximately 1-2 cm lateral to the sternum, descending behind the costal cartilages on the left side. 1
Anatomical Course and Relationship to the Heart
The LIMA originates from the left subclavian artery in the upper chest and descends vertically along the internal (posterior) surface of the anterior chest wall 2, 1
It runs parallel to the sternum, positioned approximately 1-2 cm lateral to the sternal border, traveling behind the first six costal cartilages 1, 3
The artery is located in the anterior mediastinum, anterior to the pericardium and heart itself, making it readily accessible during median sternotomy for cardiac surgery 2
The LIMA gives off multiple side branches (intercostal and perforating branches) as it descends, which are typically ligated during harvest for coronary bypass grafting 4
Surgical Relevance and Access
During coronary artery bypass grafting (CABG), the LIMA is harvested as a pedicled graft (left attached to its origin from the subclavian artery) or as a skeletonized graft, then brought down to reach the heart surface 5, 2
Its proximity to the left anterior descending (LAD) artery on the anterior surface of the heart makes it the ideal conduit for LAD revascularization, as it can reach this target vessel with minimal tension 2, 1
The in-situ LIMA (left attached proximally to the subclavian artery) provides excellent blood flow to the LAD territory when anastomosed distally to the LAD artery 6, 7