title: Oesophageal electrocardiography in healthy horses.
abstract: BACKGROUND
  In human medicine, oesophageal electrocardiography (ECG) is a well-established technique that magnifies P waves with respect to the QRS complex.
  
  
  OBJECTIVE
  To investigate the feasibility of oesophageal ECG recording in horses and its ability to produce larger P waves compared with base-apex and unipolar recordings.
  
  
  METHODS
  Bipolar and unipolar ECG were performed using oesophageal and surface electrodes. Oesophageal ECG was obtained from 6 different recording configurations at different oesophageal depths. Amplitudes of P, Q, R, S and T waves were measured from 3 different cardiac cycles for each recording configuration and depth.
  
  
  RESULTS
  Oesophageal ECG was feasible in all horses. For all oesophageal recording configurations, significantly larger P waves were recorded from a depth that equalled 'height of the withers + 10 cm' (HW(+10) ) than from any other depth. P/QRS(magn), the ratio between the P wave and QRS complex magnitudes, was largest for intraoesophageal recordings with an interelectrode distance of 10 cm, at HW(+10), where it was significantly larger than base-apex and unipolar recordings. Base-apex recording resulted in significantly smaller P waves than all other recording configurations and significantly smaller P/QRS(magn) ratios than all other recording configurations except one combined oesophageal-surface recording (E/S(low)).
  
  
  CONCLUSIONS
  Oesophageal ECG recording is feasible in horses and effective in magnifying P wave amplitude.
  
  
  CONCLUSIONS
  The procedure is promising for diagnosis of supraventricular tachydysrhythmias and might be used in electrophysiological studies and for cardiac pacing.
authors.affiliation: Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium. tinne.verheyen@ugent.be
authors.forename: T
authors.initials: T
authors.lastname: Verheyen
authors.forename: A
authors.initials: A
authors.lastname: Decloedt
authors.forename: D
authors.initials: D
authors.lastname: De Clercq
authors.forename: S
authors.initials: S
authors.lastname: Sys
authors.forename: G
authors.initials: G
authors.lastname: Van Loon
mesh_terms: D000818:Animals; D004562:Electrocardiography / Q000379:methods / Q000662:veterinary*; D004566:Electrodes; D004947:Esophagus; D006321:Heart / Q000502:physiology*; D006736:Horses / Q000502:physiology*