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Anastomosis Angle Effects in Beating-Heart Coronary Bypass Grafts: A Fluid–Structure Interaction Study

Authors :

Mohammad Saleh Kazemi¹ Nasser Fatouraee² Aisa Rassoli³

1- دانشکده مهندسی پزشکی، دانشگاه صنعتی امیرکبیر (پلی‌تکنیک تهران)، تهران، ایران 2- دانشکده مهندسی پزشکی، دانشگاه صنعتی امیرکبیر (پلی‌تکنیک تهران)، تهران، ایران 3- دانشکده مهندسی مکانیک، دانشگاه صنعتی خواجه‌ نصیرالدین طوسی

Keywords :

Fluid-Structure Interaction Method،Radial Artery،Anastomosis Angle،Time-Averaged Wall Shear Stress (TAWSS)،Oscillatory Shear Index (OSI)،von Mises Stress

Abstract :

The geometry of coronary artery bypass grafting (CABG) strongly influences the long-term success of the procedure. Among the geometrical factors, the graft-to-coronary anastomosis angle is one of the most important. Many studies have investigated this parameter using computational fluid dynamics (CFD). However, most of them ignored arterial wall compliance and the displacement of the host coronary artery caused by the beating heart. This limitation reduces the physiological relevance of their findings. In this study, the effect of the anastomosis angle was examined using a fluid–structure interaction (FSI) framework that also included the physiological motion of the host coronary artery during the cardiac cycle. Three angles (30°, 45°, and 60°) were modeled using a 15.2 cm radial artery graft. Hemodynamic and structural parameters were analyzed to provide a more realistic evaluation of graft performance. The results showed that larger anastomosis angles increased coronary outflow, time-averaged wall shear stress (TAWSS), and oscillatory shear index (OSI). At the same time, von Mises stress on the graft wall near the anastomosis decreased with larger angles. These results indicate that higher angles may improve blood supply to myocardium and reduce the risk of mechanical graft failure. However, they also increase the risk of intimal hyperplasia and restenosis at the anastomosis site. Therefore, intermediate angles, such as 45°, provided more balanced outcomes and appears to be the best compromise and may represent a preferable surgical choice. Overall, this study emphasizes the importance of including both vascular wall compliance and coronary motion in graft modeling. The findings may help surgeons select optimal anastomosis geometries for improved CABG outcomes.