Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Stark, U; Stark, G; Kasper, K; Schwarzl, I; Decrinis, M; Pilger, E; Tritthart, HA.
Influence of duration of rapid ventricular pacing on ventricular refractoriness in the presence of propafenone and lidocaine.
Pacing Clin Electrophysiol. 1997; 20(1 Pt 1):43-50
Doi: 10.1111/j.1540-8159.1997.tb04810.x
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- Co-Autor*innen der Med Uni Graz
- Pilger Ernst
- Tritthart Helmut
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- Abstract:
- Propafenone and lidocaine have a rate dependent negative dromotropic effect on intraventricular conduction. We investigated the use dependent actions of propafenone and lidocaine on intraventricular conduction in isolated guinea pig hearts perfused by the method of Langendorff. Of primary interest was how the number of stimuli of the conditioning train (S1) might influence the ventricular effective refractory period (VERP) when refractoriness is assessed at a high pacing rate. Propafenone (0.3 microM) and lidocaine (50 microM) caused a comparable prolongation of the intraventricular conduction time during sinus rhythm. During ventricular pacing in the presence of propafenone an abrupt decrease of the pacing cycle length (220 to 120 ms) resulted in an initial peak of rate dependent prolongation of the QRS interval that subsequently decreased to a stable steady-state level. Lidocaine also induced a rate dependent increase of the intraventricular conduction time up to a steady-state level. The time constant, characterizing the changes of the intraventricular conduction time after shortening the ventricular pacing cycle length from 220 to 120 ms was significantly (P < 0.01) longer in the presence of propafenone (tau = 31 +/- 4 beats; mean +/- SEM; n = 11) than for lidocaine (tau = 3 +/- 1; n = 10). Both drugs caused the greatest increase of the VERP when the number of conditioning stimuli (S1, interstimulus interval = 120 ms) was in the range of their respective time constant. However, when the number of conditioning stimuli was further increased, VERP progressively diminished. These effects may be explained by a shortening of the action potential during high rates that results in a decreased binding of propafenone to Na+ channels and by the direct shortening of repolarization period by lidocaine (Class IB drug).
- Find related publications in this database (using NLM MeSH Indexing)
- Action Potentials - drug effects
- Animals - drug effects
- Anti-Arrhythmia Agents - administration and dosage
- Atrioventricular Node - drug effects
- Bundle of His - drug effects
- Cardiac Pacing, Artificial - methods
- Electric Stimulation - methods
- Electrocardiography - drug effects
- Female - drug effects
- Guinea Pigs - drug effects
- Heart Conduction System - drug effects
- Heart Rate - drug effects
- Heart Ventricles - innervation
- Lidocaine - administration and dosage
- Male - administration and dosage
- Neural Conduction - drug effects
- Propafenone - administration and dosage
- Refractory Period, Electrophysiological - drug effects
- Regression Analysis - drug effects
- Sodium Channels - drug effects
- Time Factors - drug effects
- Find related publications in this database (Keywords)
- Lidocaine
- Propafenone
- Rate Dependency
- Refractoriness
- Time Constant