title: Influence of detomidine on atrial fibrillation cycle length measured by intracardiac electrogram recording and by colour tissue Doppler imaging in horses.
abstract: BACKGROUND
  Shortening of atrial fibrillation cycle length (AFCL) is a marker of atrial electrical remodelling due to atrial fibrillation (AF).
  
  
  OBJECTIVE
  To investigate the effect of administration of detomidine on AFCL measured invasively from an intra-atrial electrogram (AFCLEGM) and noninvasively by tissue Doppler imaging (AFCLTDI). We hypothesised that detomidine would have no effect on AFCL but would improve the ease of TDI measurements and facilitate noninvasive AFCL determination.
  
  
  METHODS
  Prospective clinical study.
  
  
  METHODS
  Measurements were performed before and after i.v. administration of 7.5 μg/kg bwt detomidine in 33 episodes of AF in 32 horses (582 ± 64 kg bwt, 10 ± 3 years old) referred for electrical cardioversion. The AFCLEGM was measured from a right atrial intracardiac electrogram. The AFCLTDI was measured from atrial colour tissue velocity curves in 5 atrial wall regions. Mean AFCLEGM and AFCLTDI without and with sedation were compared using a repeated-measures linear mixed model with Bonferroni correction for multiple comparisons and calculation of the Bland-Altman mean bias and limits of agreement between AFCLEGM and AFCLTDI.
  
  
  RESULTS
  The mean AFCL was significantly increased after sedation, but this increase was very small (mean difference +4 ms). For AFCLTDI measurements, sedation significantly improved the quality of the atrial myocardial velocity curves and the number of AF cycles that could be measured per cardiac cycle. The Bland-Altman bias between AFCLEGM without sedation and AFCLTDI with sedation ranged from -18 to +15 ms depending on wall region. Bland-Altman limits of agreement were similar between AFCLEGM without sedation and AFCLTDI without and with sedation. Therefore, noninvasive AFCLTDI measurements with sedation can be used to estimate the atrial fibrillatory rate.
  
  
  CONCLUSIONS
  Sedation facilitates noninvasive AFCL measurements but causes a slight increase in AFCL. Noninvasive AFCL measurements can be used as an indicator of atrial electrical remodelling, to study AF pathophysiology and to investigate the effect of anti-arrhythmic drugs.
authors.affiliation: Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Decloedt
authors.affiliation: Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
authors.forename: D
authors.initials: D
authors.lastname: de Clercq
authors.affiliation: Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
authors.forename: N
authors.initials: N
authors.lastname: van der Vekens
authors.affiliation: Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
authors.forename: T
authors.initials: T
authors.lastname: Verheyen
authors.affiliation: Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
authors.forename: S
authors.initials: S
authors.lastname: Ven
authors.affiliation: Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
authors.forename: G
authors.initials: G
authors.lastname: van Loon
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation / Q000628:therapy / Q000662:veterinary*; D018618:Echocardiography, Doppler, Color / Q000662:veterinary*; D004554:Electric Countershock / Q000662:veterinary; D022062:Electrophysiologic Techniques, Cardiac / Q000662:veterinary*; D006734:Horse Diseases / Q000628:therapy*; D006736:Horses; D006993:Hypnotics and Sedatives / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology*
chemical_list: D006993:Hypnotics and Sedatives; D007093:Imidazoles; C041255:detomidine
keywords: atrial remodelling; echocardiography; electrocardiography; electrophysiology; horse; sedation