Tennessee Medicine E-Journal


Internal Mammary Artery (IMA) is the best graft for Coronary Artery Bypass Graft surgery (CABG) in terms of long term survival rates and graft patency rates when compared to other grafts1,2. In traditional CABG, IMA is harvested from 1st inter-costal space and is skeletonized by ligating all the side branches, which is usually 10 cm long. In 1995, Benneti introduced Minimally Invasive Coronary Artery Bypass Graft surgery (MIDCAB) for various benefits. In this technique Left IMA (LIMA) is harvested from 5th inter-costal space and long enough to reach Left Anterior Descending Artery (LAD) around 4-6 cm 3. The later technique is used mostly for single vessel bypass and off pump CABG3. It is possible that with increased used of this technique the unligated side branches of IMA could lead to coronary steal phenomenon giving post CABG angina for which no other explanation is available.

Coronary steal syndrome secondary to subclavian stenosis proximal to LIMA bifurcation is well described4. A possibility of coronary steal phenomenon secondary to proximal large side branches of LIMA have been reported in literature5–8. These reports have proven the existence of steal phenomenon due to large secondary branches of LIMA on the basis of subjective evidence of angina free periods and documentation of occluded side branches. In 2005, Abdo et. al.,9 demonstrated radio nucleoside evidence of reversible ischemia and improvement after embolic occlusion of side branches, while in 2004 Guzon et al.,10 demonstrated no significant difference in coronary artery blood flow during rest or adenosine dilation after occlusion of side branches. Hence, the topic of coronary steal phenomenon due to side branches of IMA is inconclusive and review of existing literature is essential.