LIMA (Left internal mammary or thoracic ) is an unique artery , incidentally runs close to heart , has a privilege of supporting of human heart in its hour of crises ! . CABG surgery was started with saphenous grafts in 1967 . We have since moved on , from venous grafts to total arterial grafts . LIMA as a graft for coronary artery was a great innovation for cardiac surgery .Now , it can be stated ” CABG should not be done without a LIMA graft “
Advantages of LIMA
LIMA has good anatomical match for LAD. The 10 year patency rate is very favorable (60-80%) .LIMA is also a live graft enriched with nitric oxide , as it has native communication with subclavian artery .
The internal mammary artery originates from the under surface of the first portion of the subclavian, opposite the thyrocervical trunk. It descends behind the upper six ribs at a distance of about 1.25 cm. from the margin of the sternum, and at the level of the sixth intercostal space divides into the musculophrenic and superior epigastric arteries.
|The branches of the internal mammary are:|
There are few Anatomical issues for LIMA
Subclavian -LIMA ostial stenosis : Rare
Looping of LIMA is rarely an issue in hemodynamic point of view. But some believe a looped up LIMA is slightly prone for graft disease.Complex looping are reported rarely.
Abnormal or premature branching pattern of LIMA needs clipping as it may divert blood supply to LAD.Terminal branches can be used as a sequential graft to a branch of LAD usually a diagonal. In spite of all these issues , LIMA is rarely unsuitable either anatomically or physiologically .It is a safest vessel to graft.
Future of LIMA graft assessment.
Currently selective LIMA angiogram is the gold standard.
MDCT (64 slice) gives stunning images of LIMA graft , but unfortunately , it has little value for functional assessment .
Functional assessment of LIMA graft By angiographic frame count is being attempted in our institute.Will be reported in 2012.