The left and right internal thoracic arteries may not have equivalent histological structures.

in the LIMA-SVB. We believe that a valveless segment is preferable, and the diameter of the SVG should match the LIMA as closely as possible. In the ongoing prospective-randomized clinical trial AMI-PONT (ClinicalTrials.gov NCT01585285 [5], CIHR funded), we are assessing whether the LIMA-SVB patency is not inferior to the conventional CABG strategy combining a separated LIMA graft to the LAD and an SVG to the other coronary artery in the anterolateral territory. To avoid the risk of competitive flow that can jeopardize the LIMA-SVB patency, we require a significant stenosis of >70% of all the native coronaries connected to the LIMA-SVB. Intraoperative blood flow is measured quantitatively with the MediStim Flowmeter (Medtronic, MN, USA) in the LIMA pedicle with and without temporary occlusion of the SVB, and in the SVG itself. We found the graft flow in the LIMA pedicle to be higher in the LIMA-SVB compared with the LIMA-LAD alone [2]. If the venous segment is patent and there is no competitive flow, the sum of the measured flow into the SVB and the LIMA when the SVB is occluded should be similar to the flow in the LIMA pedicle without occlusion of the SVB. Moreover, during graft patency assessment by cardiac computed tomography angiography, we are also recording the presence of valves, if any, in the short venous segment used in the LIMA-SVB.