RF95 VENOUS VS ARTERIAL COMPOSITE Y-GRAFT IN CABG: A COMPUTATIONAL FLUID-STRUCTURE STUDY

Abstract

Background and Aim: Arterial or venous conduits used for Y-graft have different outcomes in terms of risk of restenosis and subsequent graft failure in coronary artery bypass grafting (CABG). The aim of the study was to investigate how the choice of the graft conduit predicts the risk of graft failure. Methods: We performed a computational fluid dynamics numerical simulation (FSI) analysis to describe the blood flow in the coronary arteries and grafts. Different Y-grafts with radial artery (RA) or saphenous vein (SV) were investigated by changing their mechanical properties (Young's modulus) and geometric characteristics. Coronary artery stenosis degree was also virtually varied, to assess the fluid behaviour in relation to the severity of the stenosis. Relative Residence Time (RRT) and Von Mises (VM) stresses were used as indicators of disturbed fluid-dynamic and for the analysis of the wall mechanics, respectively. Results: A more disturbed fluid-dynamic was observed for lower stenosis degree. Retrograde flow was present in the RA graft for the 50% and 70% stenosis degree. RRT values were higher in lower stenosis degree and both grafts. RRT and VM stresses were higher for the SV graft. Conclusions: Venous Y-graft is characterized by a more disturbed flow at the anastomosis site with a higher vessel's wall shear stress compared to the arterial one. Because of the potentially negative effects of competitive flow in low-grade native coronary artery stenosis, we confirm the better long-term patency in arterial CABG for critical coronary stenosis.