title: Flow patterns in externally stented saphenous vein grafts and development of intimal hyperplasia.
abstract: BACKGROUND
  Low and oscillatory wall shear stress promotes endothelial dysfunction and vascular disease. The aim of the study was to investigate the impact of an external stent on hemodynamic flow parameters in saphenous vein grafts (SVGs) and their correlation with the development of intimal hyperplasia.
  
  
  METHODS
  We performed post hoc computational fluid dynamics analysis of the randomized Venous External Support Trial, in which angiography and intravascular ultrasound data were available for 29 patients, 1 year after coronary artery bypass grafting. Each patient received 1 external stent, to either the right or left coronary territories; ≥ 1 patients with nonstented SVGs served as control(s). Diffuse flow patterns were assessed using mean values of various hemodynamic parameters, including time-averaged wall shear stress and oscillatory shear index (OSI). Focal flow disturbances were characterized using percentile analysis of each parameter.
  
  
  RESULTS
  Angiography and intravascular ultrasound data were available for 53 and 43 SVGs, respectively. The stented versus nonstented SVG failure rates were significantly lower in the left territory (17.6% vs 27.5%; P = .02), and significantly higher in the right territory (46.2% vs 13.4%; P = .01). In both diffuse and focal flow-pattern analyses, OSI was significantly lower in the stented versus nonstented SVG group (P = .009 and P < .003, respectively), whereas no significant differences were observed in time-averaged wall shear stress values. High OSI values were correlated with the development of intimal hyperplasia (P = .01).
  
  
  CONCLUSIONS
  External stenting affects SVG's hemodynamics 1 year after coronary artery bypass grafting and may mitigate the progression of intimal hyperplasia by reducing oscillatory shear stress.
authors.affiliation: Department of Bio-Medical Engineering, Afeka Academic College of Engineering, Tel Aviv, Israel.
authors.forename: Tomer
authors.initials: T
authors.lastname: Meirson
authors.affiliation: Vascular Graft Solutions, Ltd, Tel Aviv, Israel. Electronic address: eyal@graftsolutions.com.
authors.forename: Eyal
authors.initials: E
authors.lastname: Orion
authors.affiliation: Department of Cardiology, Royal Brompton Hospital, London, United Kingdom.
authors.forename: Carlo
authors.initials: C
authors.lastname: Di Mario
authors.affiliation: Department of Cardiology, Royal Brompton Hospital, London, United Kingdom; National Heart & Lung Institute, Imperial College London, London, United Kingdom.
authors.forename: Carolyn
authors.initials: C
authors.lastname: Webb
authors.affiliation: Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom.
authors.forename: Niket
authors.initials: N
authors.lastname: Patel
authors.affiliation: Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom.
authors.forename: Keith M
authors.initials: KM
authors.lastname: Channon
authors.affiliation: Department of Cardiothoracic Surgery, Tel Aviv Sourasky Medical Center, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Yanai
authors.initials: Y
authors.lastname: Ben Gal
authors.affiliation: Nuffield Department of Surgery, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom.
authors.forename: David P
authors.initials: DP
authors.lastname: Taggart
mesh_terms: D001696:Biomechanical Phenomena; D001026:Coronary Artery Bypass / Q000379:methods*; D006439:Hemodynamics; D006801:Humans; D006965:Hyperplasia; D012501:Saphenous Vein / Q000473:pathology* / Q000503:physiopathology* / Q000637:transplantation; D015607:Stents; D017539:Tunica Intima / Q000473:pathology*
keywords: coronary artery bypass graft surgery; external stent; flow pattern; intimal hyperplasia; saphenous vein graft