title: Haemodynamic properties of PTFE femoropopliteal bypass grafts as determined by a new magnetic resonance technique.
abstract: OBJECTIVE
  To apply the automatic three dimensional paraboloid (3DP) method for measurement of wall shear stress (WSS), blood flow, blood velocity, and cross sectional graft lumen area to magnetic resonance phase contrast velocity mapping data acquired from polytetrafluoroethylene (PTFE) suprageniculate 6 mm femoropopliteal bypass grafts to determine the biomechanical and haemodynamic properties immediately and three years after implantation.
  
  
  METHODS
  Two patient cohorts, each of ten patients, with intermittent claudication were investigated by the 3DP method, one group (A) within 36 h after implantation of a femoropopliteal graft and the other group (B) 35 months after implantation.
  
  
  RESULTS
  The mean blood flow was 5.9 ml/s (SD: 1.6), and WSS at peak systole was 2.2 N/m2 (SD: 0.6) 5 cm upstream to the distal anastomosis for group A, and 3.7 ml/s (SD: 1.9) and 1.9 N/m2 (SD: 0.4) for Group B. The WSS varied according to the angular position of the graft circumference. The implanted grafts were not circular but had a slightly elliptical circumference with a greater anterior/posterior diameter.
  
  
  CONCLUSIONS
  The 3DP method is a precise tool with subpixel resolution for determining the biomechanical and haemodynamic properties of implanted PTFE grafts, and it can be used to assess graft function immediately after implantation. It is potentially applicable for routine graft surveillance.
authors.affiliation: Department of Cardiothoracic and Vascular Surgery T, Aarhus University Hospital, Skejby Sygehus, Denmark.
authors.forename: H D
authors.initials: HD
authors.lastname: Sørensen
authors.forename: W P
authors.initials: WP
authors.lastname: Paaske
authors.forename: E M
authors.initials: EM
authors.lastname: Pedersen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000714:Anastomosis, Surgical; D001696:Biomechanical Phenomena; D001783:Blood Flow Velocity; D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation; D004562:Electrocardiography; D005260:Female; D005263:Femoral Artery / Q000601:surgery*; D018056:Hemorheology; D006801:Humans; D021621:Imaging, Three-Dimensional; D007383:Intermittent Claudication / Q000503:physiopathology* / Q000601:surgery*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011138:Polytetrafluoroethylene; D011150:Popliteal Artery / Q000601:surgery*
chemical_list: D011138:Polytetrafluoroethylene