title: Maximal blood flow acceleration analysis in the early diastolic phase for in situ internal thoracic 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 by transit-time flowmetry (TTFM) in the diastolic phase was assessed as a possible predictor of graft failure in coronary artery bypass patients.
  
  
  METHODS
  Max df/dt was retrospectively measured in 57 in situ left internal thoracic artery grafts. TTFM data were fitted to a 5-polynomial curve, which was derived from the first-derivative curve to measure max df/dt (5-polymial max df/dt). Abnormal TTFM was defined as a mean flow of <15 ml/min, pulsatility index of >5 or diastolic filling ratio of <50%. Postoperative coronary angiography (CAG) or multidetector computed tomography (MDCT) was performed within 1 year after surgery. The grafts were classified into four groups: Normal TTFM/Patent MDCT/CAG (N/P), Normal TTFM/Failing MDCT/CAG (N/F), Abnormal TTFM/Patent MDCT/CAG (Ab-N/P) and Abnormal TTFM/Failing MDCT/CAG graft (Ab-N/F).
  
  
  RESULTS
  By TTFM, 34 grafts were normal, 5 of which were occluded on CAG, and 23 grafts were abnormal, six of which were occluded on CAG. There were significant differences in 5-polynomial max df/dt between each group pair (P < 0.05, Mann-Whitney U-test) except for the N/F:Ab-N/P group pair; especially, 5-polynomial max df/dt was significantly lower in the Ab-N/F group compared with the other groups (Ab-N/F: 0.89 ± 0.41 vs N/P: 4.74 ± 3.18, N/F: 2.23 ± 0.65, Ab-N/P: 2.70 ± 1.31 ml/s(2), P < 0.01, Mann-Whitney U-test). The sensitivity and specificity of 5-polynomial max df/dt were, respectively, 72.7 and 80.4% (cut-off value, 1.918 ml/s(2)) for all grafts and 100 and 88.2% (cut-off value, 1.273 ml/s(2)) for abnormal TTFM grafts.
  
  
  CONCLUSIONS
  The TTFM 5-polymial max df/dt value in the early diastolic phase may be a promising predictor of future graft failure.
authors.affiliation: Department of Surgery 2, Kochi University, Nankoku, Japan takemi@mpd.biglobe.ne.jp.
authors.forename: Takemi
authors.initials: T
authors.lastname: Handa
authors.affiliation: Department of Surgery 2, Kochi University, Nankoku, Japan.
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Orihashi
authors.affiliation: Department of Surgery 2, Kochi University, Nankoku, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Nishimori
authors.affiliation: Department of Surgery 2, Kochi University, Nankoku, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Fukutomi
authors.affiliation: Department of Surgery 2, Kochi University, Nankoku, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Yamamoto
authors.affiliation: Department of Surgery 2, Kochi University, Nankoku, Japan.
authors.forename: Nobuo
authors.initials: N
authors.lastname: Kondo
authors.affiliation: Department of Surgery 2, Kochi University, Nankoku, Japan.
authors.forename: Miwa
authors.initials: M
authors.lastname: Tashiro
mesh_terms: D000054:Acceleration; D000368:Aged; D001783:Blood Flow Velocity; D017023:Coronary Angiography / Q000379:methods*; D003326:Coronary Circulation; D003331:Coronary Vessels / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery*; D003661:Decision Support Techniques; D003971:Diastole; D005260:Female; D006083:Graft Occlusion, Vascular / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D006801:Humans; D007387:Internal Mammary-Coronary Artery Anastomosis / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D061330:Multidetector Computed Tomography; D011237:Predictive Value of Tests; D011857:Radiographic Image Interpretation, Computer-Assisted; D012189:Retrospective Studies; D012212:Rheology; D012307:Risk Factors; D013997:Time Factors; D017211:Treatment Failure
keywords: Coronary artery bypass; Decision support techniques; Transit-time flowmetry