Proper orientation of the graft artery is important to ensure physiological flow direction

Arterial grafts such as right internal mammary artery (RIMA), radial artery (RA) or epigastric artery are being used with increasing frequency as free grafts or as composite grafts with left internal mammary artery (LIMA). Currently, there is no consideration of the orientation of the free artery graft to mimic the in vivo state. Hence, some grafts may be oriented such that the direction of blood flow exerted on the endothelium is reversed relative to the in vivo condition. Previous studies have shown that transient flow reversal lead to atherogenesis. A recent study demonstrated that nitric oxide is significantly reduced during reverse flow and the reduction is mediated through an increase in superoxide production. In light of these data, we suggest that the flow direction is important and recommend the assurance of proper orientation of the free arterial graft. Furthermore, we propose a new surgical procedure to modify the composite LIMA-RA or LIMA-RIMA configuration as a horseshoe or K composite graft to ensure proper orientation of the flow direction relative to the endothelium.