title: Effects of atrial fibrillation on coronary artery bypass graft flow.
abstract: OBJECTIVE
  No detailed studies exist of coronary artery bypass graft flow during atrial fibrillation. We examined the effects on bypass graft flow of atrial fibrillation following coronary artery bypass grafting.
  
  
  METHODS
  Immediately after surgical revisualization, atrial fibrillation was induced in 18 patients by high frequency atrial pacing. Hemodynamic variables were measured in sinus rhythm and atrial fibrillation. The graft flow in pedicled left internal thoracic artery grafts and in saphenous vein grafts was also measured using transit-time flowmetry.
  
  
  RESULTS
  Left internal thoracic artery graft flow had a greater diastolic component than saphenous vein graft flow, as shown by the percent diastolic time-flow integral (86 +/- 10% in the left thoracic artery and 62 +/- 12% in the saphenous vein, P < 0.0001). The induced atrial fibrillation caused significant deterioration in hemodynamics: heart rate and central venous pressure increased, and mean arterial pressure and cardiac index decreased (all P < 0.0025). In left internal thoracic artery grafts (n = 18) and also in saphenous vein grafts (n = 20), graft flow decreased significantly with atrial fibrillation (44.3 +/- 26.2 to 26.2 +/- 20.7 ml/min in the left internal thoracic artery, P = 0.0003; 39.7 +/- 15.6 to 33.3 +/- 14.3 ml/min in the saphenous vein, P = 0.001). The reduction in graft flow due to atrial fibrillation was much larger in left internal thoracic artery grafts than in saphenous vein grafts (P = 0.0008).
  
  
  CONCLUSIONS
  Direct measurement of coronary artery bypass graft flow shows that atrial fibrillation after surgery significantly reduces graft flow. The effect is much larger in left internal thoracic artery grafts with their strong diastolic component than in saphenous vein grafts.
authors.affiliation: Division of Cardiovascular Surgery, Department of Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan. h-shin@sc.itc.keio.ac.jp
authors.forename: Hankei
authors.initials: H
authors.lastname: Shin
authors.forename: Kenichi
authors.initials: K
authors.lastname: Hashizume
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Iino
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Koizumi
authors.forename: Toru
authors.initials: T
authors.lastname: Matayoshi
authors.forename: Ryohei
authors.initials: R
authors.lastname: Yozu
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000150:complications*; D001026:Coronary Artery Bypass; D003326:Coronary Circulation; D003327:Coronary Disease / Q000150:complications* / Q000601:surgery; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012501:Saphenous Vein / Q000637:transplantation; D018709:Statistics, Nonparametric; D013895:Thoracic Arteries / Q000637:transplantation