Lesson 5 of 6
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Electrocardiographic Evaluation

Can electrocardiography diagnose heart failure?

No. In many cases of heart failure the ECG is normal.

What abnormalities can be diagnosed by the ECG?

Based on the distribution of the Purkinje system throughout the heart, animals are divided into two classes:

A schematic diagram of the conduction system of the heart.

  • Class I Animals; horses and cattle:
    • extensive arborization of the Purkinje system within the ventricular wall from endocardium to epicardium
  • Class II Animals; man, dog and cat:
    • minimal branching of the Purkinje system within the ventricular wall with penetration of only the endocardium
  • In all domestic animals the ECG is the diagnostic test of choice to detect and diagnose dysrhythmias (arrhythmias).
  • In Class II animals – the ECG is also useful to provide clues to chamber enlargement.
  • ECGs can also suggest:
    • electrolyte imbalance
    • myocardial ischemia/hypoxemia
    • drug intoxication
    • thoracic effusion
    • pericardial effusion

Please refer to the course on Electrocardiography for further information.