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Intrinsic atrioventricular conductive function in horses with a second degree atrioventricular block
1Laboratory of Veterinary Surgery, College of Bioresource Sciences, Nihon University, Kanagawa, Japan.
The Journal of Veterinary Medical Science
|March 1, 1997
Summary
Horses with frequent dropped beats show impaired intrinsic atrioventricular (AV) conductive functions. Pharmacological autonomic nervous blockade confirmed these horses have lower AV conductivity and longer conduction times, indicating reduced AV function.
Area of Science:
- Veterinary Cardiology
- Electrophysiology
- Equine Health
Background:
- Atrioventricular (AV) block is characterized by frequent dropped beats in horses.
- Autonomic nervous system influences cardiac conduction, but intrinsic AV conductive function in affected horses requires further elucidation.
Purpose of the Study:
- To investigate and compare the intrinsic atrioventricular (AV) conductive functions between horses with frequent dropped beats (AV block group) and healthy controls.
- To assess the impact of pharmacological autonomic nervous blockade (PAB) on AV conductive properties in both groups.
Main Methods:
- Electrophysiological studies were performed on six horses with frequent dropped beats and five control horses.
- Pharmacological autonomic nervous blockade (PAB) was administered to assess intrinsic cardiac conduction.
- Key parameters evaluated included AV conductivity, conduction time, and refractoriness.
Main Results:
- Horses in the AV block group exhibited significantly lower AV conductivity, longer AV conduction time, and higher AV refractoriness compared to the control group, even after PAB.
- These differences persisted post-PAB, suggesting intrinsic functional deficits in the AV block group.
Conclusions:
- Horses with frequent dropped beats possess intrinsically impaired atrioventricular (AV) conductive functions.
- The findings highlight a reduced capacity for AV conduction in horses experiencing significant arrhythmias.