May 1, 1993Cardiovascular Research
Parasympathetic control of cycle length dependence of endocardial ventricular repolarisation in the intact feline heart during steady state conditions
Key result
Bilateral vagotomy reduced APDmax and CL50 in cats with intact or partially reduced sympathetic tone (P<0.05), but had no effect when beta-adrenergic blockade was applied.
Why the study?
Does bilateral vagotomy alter the rate dependence of ventricular repolarisation in anaesthetised cats?
Population
20 anaesthetised cats divided into three groups based on background sympathetic tone
Comparison
Bilateral vagotomy vs Control conditions prior to vagotomy within each…
Design
Preclinical
Authors
Discussion
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Implication
Indicates indirect vagal effects on repolarization via sympathetic antagonism in cats; leaves open direct influence and clinical translation.
Structured PICO
Does bilateral vagotomy alter the rate dependence of ventricular repolarisation in anaesthetised cats?
P
Population
20 anaesthetised cats divided into three groups to study the effects of removing vagal activity under different levels of background sympathetic tone.
I
Intervention
Bilateral vagotomy
C
Comparator
Control conditions prior to vagotomy within each group
O
Outcome
Left ventricular endocardial monophasic action potential duration (APD) parameters: APDmax and CL50surrogate
Main Result
p-value: p=<0.05
Parasympathetic modulation of ventricular repolarisation rate dependence appears to occur indirectly via vago-sympathetic reflexes or antagonism of circulating catecholamines rather than direct parasympathetic influence.
Cite This Study
Malfatto et al. (1993) studied Anaesthetised cats (animal model) (n=20). Bilateral vagotomy vs. Control conditions (before vagotomy) was evaluated on Duration of left ventricular endocardial monophasic action potential (APDmax and CL50) (p=<0.05). Bilateral vagotomy reduced APDmax and CL50 in cats with intact or partially reduced sympathetic tone (P<0.05), but had no effect when beta-adrenergic blockade was applied.