Equis ISSN 2398-2977

Cardiovascular: ECG (electrocardiography)

Contributor(s): Christopher Brown, Wendy Furness, Lesley Young

Introduction

  • An electrocardiogram (ECG) is a recording of the changes in the electrical potential difference of the heart, which occur during depolarization and repolarization of the myocardial cells and are plotted against time.
  • The body itself is a conduction system therefore this activity can be monitored from electrodes placed on the surface.
Print off the Owner factsheet on Diagnostic imaging to give to your clients.

Uses

  • Documentation and analysis of cardiac arrhythmias.
  • Monitoring, eg heart rate and rhythm during general anesthesia or drug therapy.
  • Assessing the effect of training and exercise on heart rate and rhythm.
  • Has been used to assess LV size to predict racing performance, although there is little convincing data to support this practice.

Advantages

  • Non-invasive.
  • Relatively easy to perform.
  • Can permanently document arrhythmias that may also be difficult to definitively diagnose on auscultation alone.
  • Can be used for long-term heart rate and rhythm recording to diagnose intermittent dysrhythmia in the investigation of collapse   Heart: ventricular septal defect  .
  • Can be used to assess the exercising horse.

Disadvantages

  • Many potential sources of artifacts, eg:
    • Electrical interference, eg poor electrode contact, improper grounding, other electrical equipment, fluorescent lighting, patient in contact with damp or metal suface.
    • Patient movement, eg muscle tremor, shivering, breathing, moving.
    • Interference from holder.
  • There is limited useful information on cardiac chamber size from measurement of the height and duration of the components of the equine ECG in contrast to companion animal species.

Requirements

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Preparation

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Procedure

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Morgan R (2012) Practical equine electrocardiography. UK Vet 17 (4), 10-13 VetMedResource.
  • Verheyen T et al (2012) Oesophageal electrocardiography in healthy horses. Equine Vet J 44 (6), 640-645 PubMed.
  • Fregin G F (1992) Medical evaluation of the cardiovascular system. Vet Clin N A Equine Pract (2), 329-346 PubMed.
  • Reef V B (1985) Evaluation of the equine cardiovascular system. Vet Clin N A Equine Pract (2), 275-288 PubMed.
  • Gerring E L (1984) Clinical examination of the equine heart. Equine Vet J 16 (6), 552-555 PubMed.


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