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.

Uses

• Documentation and analysis of cardiac arrhythmias.
• Monitoring, eg heart rate and rhythm during general anesthesia or drug therapy (rarely).

Advantages

• Non-invasive.
• Relatively easy to perform.
• Can permanently document dysrhythmias 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 (rarely performed in cattle).
• Can be used throughout anaesthesia to monitor cardiac function.

Disadvantages

• Many potential sources of artefacts, e.g:
  • Electrical interference, e.g. poor electrode contact, improper grounding, other electrical equipment, fluorescent lighting, patient in contact with damp or metal surface.
  • Patient movement, e.g. muscle tremor, shivering, breathing, moving.
  • Interference from holder.
• There is no useful information on cardiac chamber size from measurement of the height and duration of the components of large animal ECG in contrast to companion animal species.

Requirements

Preparation

Procedure

Outcomes

Further Reading

Publications

Refereed Papers

• Recent references from PubMed and VetMedResource.