LIMA as conduit has proved to be superior and better for early and late survival after CABG.
It is a first choice conduit because of its superior biologic characteristics, unparalleled long term patency, better clinical outcomes.
• 1. It arises from first portion of subclavian artery.
• 2. Travels downwards on the inside of ribcage from approximately a centimeter from sternum.
• 3. It is accompanied by IT vein.
• 4. It divides into musculophrenic artery and the superior epigastric artery at 6th ICS.
• 5. RITA is closer to sternal margin.
• 1. Mediastinal branches
• 2. Thymic branches
• 3. Pericardiophrenic artery
• 4. Sternal branches
• 5. Perforating branches
• 6. Twelve anterior intercostal branches, two on each side
• 7. Musculophrenic artery
• 8. Superior epigastric artery
• 1. It has resistance for atherosclerosis development, may be because of resistance of endothelium for injury.
• 2. The internal elastic lamina
inhibits cellular migration
prevents initiation of intimal hyperplasia.
• 3. Also, medial layer is thin with few SMCs
less proliferative response to mitogens like platelet derived growth factor and pulsatile muscular stretch.
• 4. Endothelium of ITA is unique. It produces vasodilators nitric oxide and prostacyclin in abundance
So has favorable response to drugs in postop period
eg. Milrinone – dilates it, noradrenaline – does not constrict it, NTG vasodilates it but not SVG.
• 5. “Downstream” effect on the coronary vasculature
coronary target appears protected distal to anastomosis
due to this endogenous secretion of vasodilators.
• 6. “Re modelling” seen in ITA
adapts to demand for flow by this diameter.
• 7. It increases flow in same way as normal coronary by increse in velocity and caliber mediated by endothelium.
Blood supply to:
• 1. ITA supplies blood to pericardium, phrenic nerve, sternum, anterior chest wall, pectoralis major, mammary gland, anterior abdominal wall, diaphragm.
• 2. Pedicle harvesting: into pedicled, semi skeletonized, skeletonized.
Sprayed / wrapped in papavarine solution.
Skeletonization – Only artery is mobilised leaving internal thoracic venous plexus intact, leads to decrease in sternal ischaemia which is seen on LIMA harvest.
ITA and veins also mobilized
Skeletonization has advantages:
• 1. It increases luminal diameter and free flow compared to pedicled graft.
• 2. Provides larger conduit
allows more sequential grafts
more targets are revascularized.
Limitations of skeletonization:
Concerns regarding vascular integrity, vasoreactivity and patency.
They demonstrated decreases in MI / reoperation / cardiac events in LIMA.
Patency LIMA –> LAD SVG -> LAD
1 yr 98% 87%
4 yr 91% 83%
10 yr 95% 61%
15 yr 88% 32%