Competitive flow in coronary bypass surgery: Is it a problem?

PURPOSE OF REVIEW: Competition flow is a common finding in arterial grafting. This phenomenon can lead to graft occlusion. RECENT FINDINGS: Internal thoracic arteries are the best equipped arterial conduit to withstand the competition flow thanks to their endothelial function. Radial as well as right gastroepiploic arteries support much less flow competition because of their different anatomy, histology and endothelial function than that of internal thoracic artery, leading to spasm and occlusion. Therefore, these two arterial conduits should be used only in case of critical lesion to avoid graft occlusion. Saphenous vein graft is the only conduit that is not significantly affected by flow competition, mainly because of its nonresistivity and common reimplantation in the aorta. Graft configuration is the second important factor influencing the equation between graft flow and native coronary flow. Therefore, composite grafting should be reserved for the case of severely stenotic coronary target, especially if multiple arterial sequential anastomoses have to be performed on the lateral-inferior wall of the heart. Finally, an accurate tool such as the fractional flow reserve to evaluate the stenosis severity should be the milestone of coronary surgery in order to decrease the rate of flow competition and improve arterial grafting functionality. CONCLUSION: Competition flow plays a crucial role in arterial grafting functionality. Grafting strategy should address this by appropriate graft choice and configuration in order to avoid graft attrition.