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 8 (2), 329-346 PubMed.
- Reef V B (1985) Evaluation of the equine cardiovascular system. Vet Clin N A Equine Pract 1 (2), 275-288 PubMed.
- Gerring E L (1984) Clinical examination of the equine heart. Equine Vet J 16 (6), 552-555 PubMed.