CARDIOLOGY

Patch ECG Compares Well to Conventional Monitor for Long-Term Cardiac Tests

By Adam Marcus

A novel system of disposable electrocardiography (ECG) patches provides reliable information about equine arrhythmias for as long as a week, a recent study shows.

Researchers in the United Kingdom tested the Carnation Ambulatory Monitor on 21 horses to determine optimal positioning of the device and to assess its performance relative to telemetric electrocardiography. The array appeared to work best when located along the ventral midline caudal to the xiphisternum. Once placed, the patches generated high-quality signals for up to 7 days, according to the researchers. However, the disposable patches performed best while the animals were at rest, providing generally unreliable results during periods of exercise.

The researchers, who published their findings in a recent issue of the Journal of Veterinary Cardiology, said the new system is easier to use than conventional ECGs, such as the Holter monitor.

“The benefit of these over the traditional wirebased monitors is their convenience and disposable nature, meaning a clinic can send these out without worrying about their expensive monitors being rolled on and broken,” said John A. Keen, BVetMed, PhD, of the Department of Veterinary Clinical Studies at the The Royal (Dick) School of Veterinary Studies and the Roslin Institute, at the University of Edinburgh, in Midlothian, who led the study. “Also, because there are no long wires dangling around, it’s more convenient to have these on for a few days and you can easily ride the horse.”

What’s more, Dr. Keen said, clinics are reluctant to send out telemetric monitors for extended periods, because the devices are expensive and, in some cases, may be their only ECG equipment.

Since publishing the paper, Dr. Keen said he has performed another 15 to 20 exams. “These are clinical cases where there is episodic/intermittent collapse—either suspected or actually observed—that may be associated with an arrhythmia or cases where there is a perceived increased risk of arrhythmia, or where there is an arrhythmia that I feel warrants longer-term monitoring to fully characterize the frequency of the arrhythmia.”

Dr. Keen described the quality of the studies as “generally very good at rest, and these examinations have invariably been useful diagnostically,” but added that they are not a replacement for standard ECGs during exercise testing.

“The significant artefact associated with exercise drowns out the quality of the ECG signal. Even with a standard ECG the exercising trace can be a problem and one of the 'holy grails' for us equine cardiologists is artefact-free ECG traces at exercise—often a problem in anything other than racehorses! I’d like to play around with patch positioning some more to see if I can get these devices any better for exercise ECGs but my suspicion is it won’t get that much better with the current technology.” MeV

For more information:

Keen JA et al. Evaluation of a novel ambulatory electrocardiogram monitor (the Carnation Ambulatory Monitor) for use in horses. J Vet Cardiol. 2021;34:16-28. https://doi.org/10.1016/j.jvc.2020.12.005