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Home / Equine Research Bank / Animals (Basel) / Cartilaginous Intrusion of the Atrioventricular Node in a Qu...
Animals : an open access journal from MDPI2022; 12(21); 2915; doi: 10.3390/ani12212915

Cartilaginous Intrusion of the Atrioventricular Node in a Quarter Horse with a High Burden of Second-Degree AV Block and Collapse: A Case Report.

Abstract: Second-degree atrioventricular (AV) block is the most common cardiac arrhythmia in horses, affecting 40-90% depending on breed. Usually, the AV blocks occur while the horses are resting and disappear upon exercise and are, therefore, considered to be uneventful for horses. However, if the AV blocks occur frequently, this may result in syncope and collapse. Identifying the cause of second-degree AV block is difficult and often subscribed to high vagal tone. In this report, we present an eight-year-old Quarter horse with a high burden of second-degree AV blocks and multiple collapses. The clinical examination, including neurological examination, blood analysis, 24-h ECG recording and cardiac echocardiography, did not reveal any signs of general or cardiovascular disease besides a high burden of second-degree AV blocks (~300 blocks per hour) and a hyperechoic area in the AV nodal region. An implantable loop recorder (ILR) was inserted to monitor the cardiac rhythm. The ILR detected several consecutive second-degree AV blocks and pauses above 5 s. However, unfortunately, no recordings were available during the collapses. Eventually, the horse was euthanized and the heart inspected. The aortic root was severely cartilaginous and appeared to penetrate the AV node, especially in the His bundle region, possibly explaining the hampered AV conduction. Nevertheless, it is still uncertain if the AV nodal disruption caused the collapses and more knowledge on AV nodal diseases in horses is warranted.
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Publication Date: 2022-10-24 PubMed ID: 36359039PubMed Central: PMC9657453DOI: 10.3390/ani12212915Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research article discusses a case study of an eight-year-old Quarter horse suffering from frequent second-degree atrioventricular (AV) block and multiple collapses. The study investigates the potential relationship between these AV blocks and the horse’s overall cardiovascular health, leading to a discovery of an unusual condition in the horse’s heart.

Introduction to the Case and Condition

  • The article revolves around a Quarter horse that was dealing with a high occurrence of second-degree atrioventricular (AV) block. This is an abnormal heart rhythm that affects between 40% and 90% of horses, depending on the breed. It is generally an asymptomatic condition that occurs when the horse is resting and disappears with exercise.
  • However, in this particular case, it was observed that the horse was not only suffering from AV blocks more frequently than normal, resulting in about 300 blocks per hour, but it was also experiencing multiple collapses. This raised concerns about the potential implications of persistent AV block on the health and well-being of the horse.

Clinical Examination and Monitoring

  • In an attempt to identify the cause of the recurring AV blocks, the horse underwent a series of tests. These included a neurological examination, blood analysis, a 24-hour ECG recording, and cardiac echocardiography.
  • The results did not indicate any signs of general health issues or cardiovascular disease, except for the unusually high number of second-degree AV blocks.
  • An implantable loop recorder (ILR) was inserted to monitor the horse’s heart rhythm closely. The device recorded several consecutive second-degree AV blocks and pauses lasting more than 5 seconds. Unfortunately, no recordings were available during the horse’s collapses.

Post-Mortem Examination

  • Despite the monitoring efforts, the horse had to be euthanized. The post-mortem examination of the horse revealed that the aortic root was abnormally cartilaginous and appeared to be invading the AV node of the heart, particularly in the His bundle region.
  • This finding suggested that the hardened and intrusive structure could potentially be obstructing the normal conduction of signals in the heart, thus causing the instances of AV block.

Conclusion and Future Directions

  • Although an association can be drawn between the cartilaginous intrusion in the AV node and the horse’s condition, it remains inconclusive whether this was the sole cause of the horse’s collapses.
  • Additional research and knowledge about AV nodal diseases in horses are necessary to confirm this hypothesis and potentially uncover more information about the cause-effect relationship between heart structure abnormalities and cardiovascular conditions in horses.

Cite This Article

APA
Nissen SD, Saljic A, Kjeldsen ST, Jespersen T, Hopster-Iversen C, Buhl R. (2022). Cartilaginous Intrusion of the Atrioventricular Node in a Quarter Horse with a High Burden of Second-Degree AV Block and Collapse: A Case Report. Animals (Basel), 12(21), 2915. https://doi.org/10.3390/ani12212915

Publication

Animals : an open access journal from MDPI
ISSN: 2076-2615
NlmUniqueID: 101635614
Country: Switzerland
Language: English
Volume: 12
Issue: 21
PII: 2915

Researcher Affiliations

Nissen, Sarah Dalgas
  • Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Højbakkegaard Allé 5, 2630 Taastrup, Denmark.
Saljic, Arnela
  • Institute of Pharmacology, West German Heart and Vascular Centre, University of Duisburg-Essen, 45117 Essen, Germany.
  • Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark.
Kjeldsen, Sofie Troest
  • Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Højbakkegaard Allé 5, 2630 Taastrup, Denmark.
Jespersen, Thomas
  • Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark.
Hopster-Iversen, Charlotte
  • Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Højbakkegaard Allé 5, 2630 Taastrup, Denmark.
Buhl, Rikke
  • Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Højbakkegaard Allé 5, 2630 Taastrup, Denmark.

Conflict of Interest Statement

The authors declare no conflict of interest.

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