Heart rate variability analysis in horses for the diagnosis of arrhythmias
Heart rate variability (HRV) analysis was initially carried out to identify changes in vago-symphathetic balance. More recently, taking the best advantage of the latest technology, it has been used to identify cardiac arrhythmias, particularly atrial fibrillation (AF).
HRV is the term used to describe oscillations in rate between consecutive cardiac cycles, monitored by ECG, heart rate monitoring devices or other technology. Increased variability can be detected in several situations: a normal and physiological response to wavering parasympathetic tone, in pathological conditions associated with particular breathing patterns or arrhythmias.
In human medicine, HRV analysis has been utilized in a wide variety of fields. In equine medicine, its investigation to diagnose arrhythmias is an emerging field of research. This review article summarizes the information currently available about HRV and its use in horses.
Among the main indications for performing HRV analysis in horses with arrhythmias are comparing the response of a medical or surgical therapy, detecting subtle arrhythmias, comparing changes in arrhythmia frequency over time and monitoring the evolution of the disease.
There are also a few important factors to consider when collecting data for HRV analysis, such as the type of recording devices, the timing, the length of the recordings, if the animal is resting or exercising, the selection of using RR interval or PP interval and post manual filtering of artefacts.
HRV analysis can be extremely useful when examining data sets acquired from individuals with arrhythmias. It will enable us to improve our understanding of disease mechanisms, predict adverse outcomes and improve the therapeutic approaches for horses with cardiac arrhythmias.
Mitchell K.J. and Schwarzwald C.C. (2021) Heart rate variability analysis in horses for the diagnosis of arrhythmias. The Veterinary Journal, Vol.268, 105590 https://doi.org/10.1016/j.tvjl.2020.105590
