title: Effects of heart rate on flow velocity of the left atrial appendage in patients with nonvalvular atrial fibrillation.
abstract: OBJECTIVE
  Flow velocity of the left atrial appendage (LAA) is thought to be important in thrombus formation in association with blood stasis and the development of spontaneous echo contrast. The effects of heart rate on peak flow velocity of LAA have not been studied in patients with nonvalvular atrial fibrillation.
  
  
  METHODS
  Using transesophageal Doppler echocardiography, peak flow velocity of the LAA was measured at the junction between the left atrium and the LAA during left ventricular (LV) systole and diastole in 21 patients with nonvalvular atrial fibrillation. In six cases, the average peak flow velocity of the LAA for 10 consecutive beats with moderately long R-R intervals (LI beats) was compared with those of 3-5 consecutive beats with extremely short R-R intervals (SI beats).
  
  
  RESULTS
  Average peak flow velocity of the LAA during LV diastole was significantly higher than that during LV systole (26.5 +/- 15.7 vs. 19.3 +/- 10.4 cm/s, p < 0.01). In SI beats, average peak flow velocity of the LAA was significantly lower than that in LI beats (17.1 +/- 12.1 vs. 21.2 +/- 12.9 cm/s, p < 0.01).
  
  
  CONCLUSIONS
  An increased heart rate reduced the peak flow velocity of the LAA in patients with nonvalvular atrial fibrillation, which would promote blood stasis in the LAA.
authors.affiliation: Second Department of Internal Medicine, Gifu University School of Medicine, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Noda
authors.forename: M
authors.initials: M
authors.lastname: Arakawa
authors.forename: H
authors.initials: H
authors.lastname: Miwa
authors.forename: Y
authors.initials: Y
authors.lastname: Ito
authors.forename: K
authors.initials: K
authors.lastname: Kagawa
authors.forename: K
authors.initials: K
authors.lastname: Nishigaki
authors.forename: S
authors.initials: S
authors.lastname: Hirakawa
authors.forename: H
authors.initials: H
authors.lastname: Fujiwara
mesh_terms: D000328:Adult; D000368:Aged; D001281:Atrial Fibrillation / Q000000981:diagnostic imaging / Q000503:physiopathology*; D016275:Atrial Function / Q000502:physiology*; D001783:Blood Flow Velocity / Q000502:physiology; D015150:Echocardiography, Doppler; D017548:Echocardiography, Transesophageal; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D012039:Regional Blood Flow; D016277:Ventricular Function, Left / Q000502:physiology