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Veterinary journal (London, England : 1997)2005; 170(1); 124-127; doi: 10.1016/j.tvjl.2004.08.013

Transient complete atrioventricular block following transvenous electrical cardioversion of atrial fibrillation in a horse.

Abstract: Transvenous electrical cardioversion was attempted in a horse with drug refractory atrial fibrillation. A temporary pacing catheter and two defibrillation catheters were inserted transvenously into the right ventricular apex, the right atrium and the pulmonary artery, respectively. Under general anaesthesia 100, 200, 300 and 360 J monophasic shocks were delivered between both defibrillation catheters but sinus rhythm could not be restored. Immediately after the 200, 300 and 360 J shock, transient third-degree atrioventricular block occurred for a period of, respectively, 15, 40 and 55 s. These periods of profound bradycardia were corrected by temporary right ventricular pacing until spontaneous conduction resumed. It is concluded that temporary right ventricular pacing should be available during electrical cardioversion of atrial fibrillation in horses.
Publication Date: 2005-07-05 PubMed ID: 15993796DOI: 10.1016/j.tvjl.2004.08.013Google Scholar: Lookup
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Summary

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This research examined a case where a horse with a heart disorder called atrial fibrillation, which was not responsive to drugs, underwent an electrical treatment. After the treatment, the horse showed signs of temporary heart block, which were then corrected with artificial pacing. The study suggests having an artificial heart pacemaker available during such procedures on horses.

Method and Procedure

  • The horse was suffering from a condition known as atrial fibrillation, which previous drug treatments had failed to correct.
  • To treat this, an approach called transvenous electrical cardioversion was attempted.
  • A temporary pacing catheter and two defibrillation catheters were inserted into the horse’s heart via veins. These devices are used to deliver electric shocks.
  • The horse was placed under general anaesthesia for the procedure.
  • Electric shocks of varying intensities were delivered between the defibrillation catheters. Despite these efforts, the horse’s regular heart rhythm was not restored.

Findings and Observations

  • Immediately after the shocks of 200, 300 and 360 joules, the horse experienced a temporary third-degree atrioventricular block that lasted 15, 40, and 55 seconds respectively.
  • Third-degree atrioventricular block is a severe type of heart block where the signals from the atria to the ventricles are completely interrupted.
  • Durning these periods, the horse’s heart rate dropped significantly (profound bradycardia).
  • This was corrected by using the temporary right ventricular pacemaker until the horse’s own heart conduction resumed.

Conclusions and Recommendations

  • The study concluded that right ventricular pacing should be available during electrical cardioversion for atrial fibrillation in horses.
  • This is because electrical cardioversion can potentially induce periods of profound bradycardia or atrioventricular block, which can be managed effectively with temporary right ventricular pacing.
  • Therefore, being prepared with the option of pacing can help to manage any complications during the procedure, ensuring the safety and health of the horse.

Cite This Article

APA
van Loon G, De Clercq D, Tavernier R, Amory H, Deprez P. (2005). Transient complete atrioventricular block following transvenous electrical cardioversion of atrial fibrillation in a horse. Vet J, 170(1), 124-127. https://doi.org/10.1016/j.tvjl.2004.08.013

Publication

ISSN: 1090-0233
NlmUniqueID: 9706281
Country: England
Language: English
Volume: 170
Issue: 1
Pages: 124-127

Researcher Affiliations

van Loon, G
  • Large Animal Internal Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium. Gunther.vanLoon@UGent.be
De Clercq, D
    Tavernier, R
      Amory, H
        Deprez, P

          MeSH Terms

          • Animals
          • Atrial Fibrillation / therapy
          • Atrial Fibrillation / veterinary
          • Diagnosis, Differential
          • Electric Countershock / adverse effects
          • Electric Countershock / veterinary
          • Electrocardiography / veterinary
          • Female
          • Heart Block / diagnosis
          • Heart Block / etiology
          • Heart Block / veterinary
          • Horse Diseases / therapy
          • Horses

          Citations

          This article has been cited 3 times.
          1. Avison A, Gelzer AR, Reef VB, Wulster Bills KB, de Solis CN, Kraus MS, Slack J, Stefanovski D, Deacon LJ, Underwood C. Twenty-four hour continuous transvenous temporary right ventricular pacing in healthy horses. J Vet Intern Med 2024 May-Jun;38(3):1751-1764.
            doi: 10.1111/jvim.17027pubmed: 38514200google scholar: lookup
          2. Vernemmen I, Van Steenkiste G, Dufourni A, Decloedt A, van Loon G. Transvenous electrical cardioversion of atrial fibrillation in horses: Horse and procedural factors correlated with success and recurrence. J Vet Intern Med 2022 Mar;36(2):758-769.
            doi: 10.1111/jvim.16395pubmed: 35246994google scholar: lookup
          3. Reef VB, Bonagura J, Buhl R, McGurrin MK, Schwarzwald CC, van Loon G, Young LE. Recommendations for management of equine athletes with cardiovascular abnormalities. J Vet Intern Med 2014 May-Jun;28(3):749-61.
            doi: 10.1111/jvim.12340pubmed: 24628586google scholar: lookup