title: Maximal blood flow acceleration analysis in the early diastolic phase for aortocoronary artery bypass grafts: a new transit-time flow measurement predictor of graft failure following coronary artery bypass grafting.
abstract: OBJECTIVE
  Maximal graft flow acceleration (max df/dt) determined using transit-time flowmetry (TTFM) in the diastolic phase was assessed as a potential predictor of graft failure for aortocoronary artery (AC) bypass grafts in coronary artery bypass patients.
  
  
  METHODS
  Max df/dt was retrospectively measured in 114 aortocoronary artery bypass grafts. TTFM data were fitted to a 9-polynomial curve, which was derived from the first-derivative curve, to measure max df/dt (9-polynomial max df/dt). Abnormal TTFM was defined as a mean flow of <15 ml/min, a pulsatility index of >5 or a diastolic filling ratio of <50 %. Postoperative assessments were routinely performed by coronary artery angiography (CAG) at 1 year after surgery.
  
  
  RESULTS
  Using TTFM, 68 grafts were normal, 4 of which were failing on CAG, and 46 grafts were abnormal, 21 of which were failing on CAG. 9-polynomial max df/dt was significantly lower in abnormal TTFM/failing by the CAG group compared with abnormal TTFM/patent by the CAG group (1.08 ± 0.89 vs. 2.05 ± 1.51 ml/s(2), respectively; P < 0.01, Mann-Whitney U test, Holm adjustment).
  
  
  CONCLUSIONS
  TTFM 9-polynomial max df/dt in the early diastolic phase may be a promising predictor of future graft failure for AC bypass grafts, particularly in abnormal TTFM grafts.
authors.affiliation: Department of Surgery 2, Kochi University, Nankoku, Kochi, 783-8505, Japan. takemi@mpd.biglobe.ne.jp.
authors.forename: Takemi
authors.initials: T
authors.lastname: Handa
authors.affiliation: Department of Surgery 2, Kochi University, Nankoku, Kochi, 783-8505, Japan.
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Orihashi
authors.affiliation: Department of Surgery 2, Kochi University, Nankoku, Kochi, 783-8505, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Nishimori
authors.affiliation: Department of Surgery 2, Kochi University, Nankoku, Kochi, 783-8505, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Yamamoto
mesh_terms: D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology*; D001026:Coronary Artery Bypass; D003971:Diastole / Q000502:physiology*; D005260:Female; D006083:Graft Occlusion, Vascular / Q000175:diagnosis* / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012212:Rheology / Q000379:methods*
keywords: Coronary artery bypass; Decision support techniques; TTFM