title: Impact of top end anastomosis design on patency and flow stability in coronary artery bypass grafting.
abstract: For coronary artery bypass grafting (CABG), free grafts such as a saphenous vein or radial artery are often used for grafts to the lateral and posterior walls. However, the relationship between top-end anastomosis design and long-term patency remains unknown. Because coronary artery blood flow is dominant during diastole, top-end anastomosis may work better if the graft is directed towards the apex, whereas the shortest graft pathway appears to be most efficient. Using computational fluid dynamic models, we evaluated the hemodynamic variables that were affected by the angle of the top-end anastomosis. We created three-dimensional geometries of the aortic root with coronary arteries that involved 75 % stenosis in the obtuse marginal and postero-lateral branches. Two bypass models under vasodilator administration were created: in a"Model A", the top-end anastomosis is parallel to the long axis of the ascending aorta and the graft passed over the conus directed towards the apex; in a "Model B", the top-end anastomosis is directed toward the shortest pathway, and form near the right angles to the long axis of the ascending aorta. Wall shear stress (WSS) and its fluctuation, an oscillatory shear index (OSI) were evaluated to predict fibrosis progression at the anastomosis site and graft flow. Graft flow was 197.3 ml/min and 207.3 ml/min in the "Model A" and "Model B", respectively. The minimal WSS value inside the graft with the "Model A" and "Model B" was 0.53 Pa and 4.09 Pa, respectively, and the OSI value was 0.46 and 0.04, respectively. The top-end anastomosis of a free graft should be directed vertically towards the aorta to achieve the shortest graft pathway to maintain a high graft flow rate and to avoid the risks of endothelial fibrosis and plaque progression over the long-term after CABG.
authors.affiliation: Department of Cardiovascular Surgery, Kitasato University School of Medicine, Sagamihara, Japan.|Department of Cardiovascular Surgery, Shin-Yurigaoka General Hospital, Kawasaki, Japan.|Department of Cardiac Surgery, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Sachi
authors.initials: S
authors.lastname: Koyama
authors.affiliation: Department of Cardiovascular Surgery, Kitasato University School of Medicine, Sagamihara, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kitamura
authors.affiliation: Department of Cardiovascular Surgery, Kitasato University School of Medicine, Sagamihara, Japan. keiichiitatani@gmail.com.|Department of Hemodynamic Analysis, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami, Sagamihara, Kanagawa, 252-0374, Japan. keiichiitatani@gmail.com.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Itatani
authors.affiliation: Department of Cardiology, Hokkaido Cardiovascular Hospital, Sapporo, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Yamamoto
authors.affiliation: Department of Hemodynamic Analysis, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami, Sagamihara, Kanagawa, 252-0374, Japan.
authors.forename: Shohei
authors.initials: S
authors.lastname: Miyazaki
authors.affiliation: Department of Cardiovascular Surgery, Kitasato University School of Medicine, Sagamihara, Japan.
authors.forename: Norihiko
authors.initials: N
authors.lastname: Oka
authors.affiliation: Department of Cardiovascular Surgery, Kitasato University School of Medicine, Sagamihara, Japan.|Department of Cardiovascular Surgery, Shin-Yurigaoka General Hospital, Kawasaki, Japan.
authors.forename: Kouki
authors.initials: K
authors.lastname: Nakashima
authors.affiliation: Department of Cardiovascular Surgery, Kitasato University School of Medicine, Sagamihara, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Horai
authors.affiliation: Department of Cardiac Surgery, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Ono
authors.affiliation: Department of Cardiovascular Surgery, Kitasato University School of Medicine, Sagamihara, Japan.
authors.forename: Kagami
authors.initials: K
authors.lastname: Miyaji
mesh_terms: D000714:Anastomosis, Surgical; D001783:Blood Flow Velocity; D003198:Computer Simulation; D001026:Coronary Artery Bypass / Q000009:adverse effects / Q000379:methods*; D003326:Coronary Circulation; D023921:Coronary Stenosis / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D018450:Disease Progression; D042783:Endothelial Cells / Q000473:pathology; D005355:Fibrosis; D006801:Humans; D008955:Models, Cardiovascular; D058226:Plaque, Atherosclerotic; D012720:Severity of Illness Index; D013314:Stress, Mechanical; D016896:Treatment Outcome; D014654:Vascular Patency
keywords: CABG; Computational fluid dynamics; Coronary artery bypass graft; Top-end anastomosis; Wall shear stress