Reduced left internal mammary artery blood flow on normal sternal retraction

The left internal mammary artery is the conduit of choice for bypassing the left anterior descending artery. A 72-year-old man underwent off-pump triple-vessel coronary artery bypass. The left internal mammary artery was harvested with brisk blood flow from the distal artery on completion of harvesting, but normal sternal retraction with a Medtronic OctoBase retractor led to cessation of flow. A vein graft was utilized for the left anterior descending artery, and the internal mammary artery was grafted to the first diagonal branch. Computed tomography-angiography on postoperative day 5 demonstrated no possible cause of the reduced flow on sternal retraction.