title: Do coronary bypass graft flows differ between on-pump and off-pump operations?
abstract: BACKGROUND
  The aim of this study is to compare hemodynamic factors in coronary bypass grafts on-pump and off-pump.
  
  
  METHODS
  Two propensity score-matched groups of 89 patients each including 408 dual beam Doppler flow measurements were compared. The study included only patent and single terminolateral bypass grafts.
  
  
  RESULTS
  Flow was 64.9 +/- 37.3 mL/min in the on-pump group versus 58.6 +/- 35.0 mL/min in the off-pump group (p = 0.063); velocity was 23.8 +/- 10.5 versus 20.5 +/- 10.4 cm/s (p = 0.004); resistance measured as mm Hg/(mL/min(-1)) was 1.50 +/- 1.09 versus 1.76 +/- 1.14 (p = 0.020); pulsatility index was 1.98 +/- 1.52 versus 2.44 +/- 1.62 (p = 0.004). The hematocrit was 23.5 +/- 3.8% in the on-pump and 32.9 +/- 4.1% in the off-pump groups (p < 0 0.001). Multivariate analysis showed that hematocrit was the most significant factor influencing flow (p < 0.001) and velocity (p < 0.001), along with resistance (p = 0.004) and pulsatility index (p < 0.001). In a subset of 50 hemodynamic measurements made on left internal thoracic arteries implanted onto left anterior descending arteries and matched for hematocrit, there were no differences between on-pump and off-pump groups regarding flow, velocity, resistance, or pulsatility index.
  
  
  CONCLUSIONS
  Off-pump compared with on-pump bypass surgery is associated with lower velocity and higher resistance in the grafts, mainly caused by changes in hematocrit and viscosity related to hemodilution.
authors.affiliation: Department of Cardiovascular and Thoracic Surgery, University Clinics of Mont Godinne, Université Catholique de Louvain, Yvoir, Belgium. louagie@chir.ucl.ac.be
authors.forename: Yves A G
authors.initials: YA
authors.lastname: Louagie
authors.forename: Jacques
authors.initials: J
authors.lastname: Jamart
authors.forename: André
authors.initials: A
authors.lastname: Gruslin
mesh_terms: D000368:Aged; D001809:Blood Viscosity; D001026:Coronary Artery Bypass; D047549:Coronary Artery Bypass, Off-Pump; D003324:Coronary Artery Disease / Q000601:surgery; D005260:Female; D006400:Hematocrit; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D014655:Vascular Resistance