LIMA-Left internal mamary  artery is the most common arterial  graft used in CABG.It is anastomosed with LAD /and or diagonal artery. Routine visualisation of LIMA is advocated by many , but it is required only  in patients with critical CAD.

LIMA angiogram is done

1. To confirm the presence of LIMA .
2. To exclude subclavian  stenosis.(If present hand can steal blood from heart !)
3. To rule out disease of LIMA (Which is unlikely )
4. Diameter of LIMA should be matched with LAD .LIMA with large lumens can accelerate restenosis in LAD due excess flow induced endothelial reaction
5. To identify  any early branching of LIMA .This can divert the  blood flow and underperfuse LAD.
6. Terminal bifurcation  of LIMA can some times be used as a sequential graft to LAD/LCX/OM
7. Tortuosity and looping of  LIMA is common but generally has no hemodynamic significance.
8. LIMA may  provide vital  nutritional support to sternum through direct or   intercostal branches .If  LIMA dependent sternal  blood supply is found to be significant ,   sufficient precautions to be taken and anticipate sternal ischemia related complications.This is especially important in diabetic subjects.