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Do lidocaine and verapamil affect overdrive-induced suppression of pacemakers in dogs with complete atrioventricular block?
Do lidocaine and verapamil affect overdrive-induced suppression of pacemakers in dogs with complete atrioventricular block?
In a canine model of complete AV block, lidocaine but not verapamil prolonged overdrive suppression, suggesting ventricular pacemaker automaticity is not slow channel-dependent.
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Supports lidocaine-sensitive but verapamil-insensitive ventricular automaticity in dogs; leaves open relevance to human complete AV block.
When the ventricle is electrically stimulated at a faster rate, the cessation of the drive is followed by a temporary suppression of automaticity (overdrive suppression). The effects of lidocaine and verapamil on overdrive suppression were studied in dogs. Lidocaine slowed the ventricular escape rate and prolonged the pause following overdrive; occasionally, it was about twice the next succeeding RR interval. On the contrary, verapamil influenced neither the ventricular escape rate nor the pause following overdrive. It is suggested that lidocaine not only suppresses the automaticity of ventricular escape pacemaker but also induces exit block and that the spontaneous depolarization of the ventricular pacemaker is not slow channel-dependent.
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Watanabe et al. (1983) studied this question.
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