Key result
After pharmacological autonomic nervous blockade, horses with second-degree AV block exhibited significantly longer mean PR intervals (495 vs 418 msec, p<0.01) than controls, suggesting intrinsic AV conductive dysfunction.
Why the study?
Does pharmacological autonomic nervous blockade reveal differences in intrinsic AV conductive function between horses with and without frequent second-degree AV block?
Population
11 horses: 6 with frequent second-degree AV block and 5 controls.
Comparison
Pharmacological autonomic nervous blockade with… vs Baseline and control group of horses without…
Design
Preclinical
Follow-up
5 minutes after injection
Authors
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Should not yet inform equine AV block management; leaves open intrinsic conduction defects for translational research.
Case-Control (n=11)
No
Does pharmacological autonomic nervous blockade reveal differences in intrinsic AV conductive function between horses with and without frequent second-degree AV block?
Absolute Event Rate: 495% vs 418%
p-value: p=<0.01
Intrinsic AV conductive function impairment, rather than just increased vagal tone, plays an important role in the mechanism of second-degree AV block in horses.
YAMAYA et al. (1997) conducted a case-control in Second degree Atrioventricular Block (n=11). Pharmacological autonomic nervous blockade (propranolol and atropine) vs. Control group was evaluated on Mean PR interval during atrial pacing after pharmacological autonomic nervous blockade (msec) (p=<0.01). After pharmacological autonomic nervous blockade, horses with second-degree AV block exhibited significantly longer mean PR intervals (495 vs 418 msec, p<0.01) than controls, suggesting intrinsic AV conductive dysfunction.
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