The effect of Verapamil on the cardiac conduction system in man

Abstract

Summary Using His bundle electrograms the effect of Verapamil on the specialized conduction system in eleven patients was studied during routine cardiac catheterization. In five patients, the absolute and relative refractory periods of the A-V node, and retrograde conduction through the A-V node was studied using programmed electrical stimulation techniques. Verapamil caused prolongation of anterograde and retrograde A-V nodal conduction times. The effect on anterograde conduction was only partly reversible with Atropine. No significant effect on the remainder of the conduction system was observed. It is concluded that Verapamil has a direct effect on A-V nodal conduction independent of any vagotonic effect.