title: Analysis of the atrial repolarization wave in dogs with third-degree atrioventricular block.
abstract: OBJECTIVE
  To characterize the electrocardiographic features of the atrial repolarization (Ta) wave in dogs with third-degree atrioventricular (AV) block.
  
  
  METHODS
  ECGs of 36 dogs with third-degree AV block and no identifiable structural heart diseases.
  
  
  METHODS
  Standard 12-lead ECGs were acquired with a digital system, and measurements were manually edited.
  
  
  RESULTS
  A Ta wave was detectable in all dogs for at least 1 ECG lead. The Ta wave had negative polarity in leads I, II, III, and aVF and positive polarity in leads aVL and aVR, with a mean electrical axis of -114.26°. Mean duration and mean amplitude of the Ta wave in lead II were 140.2 milliseconds and -0.09 mV, respectively, with the ratio for the Ta-to-P wave duration of 2.3 and the ratio of Ta-to-P wave amplitude of -0.35. Significant correlations were found between the Ta wave duration and duration of the P-Ta interval, Ta wave amplitude and the ECG lead, Ta wave duration and body weight, and duration of the P-Ta interval and atrial rate. Measurements of the Ta wave were repeatable.
  
  
  CONCLUSIONS
  Measurements of the Ta wave in dogs with third-degree AV block were repeatable. The values for the Ta wave reported here can be used as reference values for dogs with AV conduction disturbances and an echocardiographically normal atrial size. Further studies are needed to validate these results in dogs with structural heart diseases.
authors.affiliation: Cardiology Division, Clinica Veterinaria Malpensa, Viale Marconi 27, Samarate (VA) Italy.
authors.forename: Manuela
authors.initials: M
authors.lastname: Perego
authors.forename: Stefano
authors.initials: S
authors.lastname: Skert
authors.forename: Roberto A
authors.initials: RA
authors.lastname: Santilli
mesh_terms: D000818:Animals; D054537:Atrioventricular Block / Q000175:diagnosis / Q000503:physiopathology / Q000662:veterinary*; D004283:Dog Diseases / Q000175:diagnosis* / Q000503:physiopathology; D004285:Dogs; D004562:Electrocardiography / Q000379:methods* / Q000662:veterinary; D005260:Female; D006325:Heart Atria / Q000503:physiopathology*; D008297:Male; D012016:Reference Values