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What is the significance of looping and early branching of LIMA during CABG ?

Posted in cardiac surgery, tagged , , , , , on June 2, 2011| Leave a Comment »

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  .

Anatomy

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:
Pericardiacophrenic. Intercostal.
Anterior Mediastinal. Perforating.
Pericardial. Musculophrenic.
Sternal. Superior Epigastric.

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.

A loop and a early branch of LIMA : What is the implication ?

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.

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Why do we do LIMA angiogram routinely during coronary angiogram ?

Posted in cardiac surgery, cardiology-Anatomy, tagged , , , , , , , on December 11, 2010| Leave a Comment »

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.

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