References
How to interpret an electrocardiogram
Abstract
Electrocardiography is the ultimate tool for diagnosing suspected cardiac arrhythmia, and the required equipment is readily available to an equine practitioner. Careful interpretation is essential to determine whether an arrhythmia is significant, either as a cause of poor performance or as a risk for collapse and sudden death. A good quality echocardiography recording is essential, usually an exercising electrocardiogram and a recording over 24 hoursl. Echocardiographical interpretation is aided by modern electrocardiogram analysis software, and technology enables access to a second opinion when required. Vagally-mediated arrhythmias are common in horses at rest, but should be overridden by exercise. Atrial fibrillation or frequent ectopic beats during exercise warrants further cardiac evaluation.
It is important to consider why electrocardiography is being performed as this dictates what tests are required and how you interpret the findings. Electrocardiography is performed during the investigation of poor performance in athletes or during the investigation of an arrhythmia or cardiac murmur identified at routine examination. Important additional information includes any history of exercise intolerance, the horse's signalment and intended use.
This is easily achieved with basic equipment and is useful for investigating sustained arrhythmias present at rest. However, it may require follow up with an exercising electrocardiogram (ECG). An intermittent problem can be investigated using 24-hour Holter ambulatory ECG. A 24-hour recording generates a substantial amount of data to analyse.
This requires equipment that is able to record or transmit the ECG to a recording device. The exercise test should be representative of the horse's normal exercise level and should include the recovery period. It is used to assess whether an arrhythmia present at rest resolves during exercise or, conversely, whether an arrhythmia becomes apparent during exercise or recovery.
Register now to continue reading
Thank you for visiting UK-VET Equine and reading some of our peer-reviewed content for veterinary professionals. To continue reading this article, please register today.