Frequency-dependent effects of amitriptyline and maprotiline on conduction in the guinea pig His-Purkinje-system in vivo.

In the Cardiac Arrhythmia Suppression Trial antiarrhythmic drug therapy with slow kinetic sodium channel blockers (class Ic antiarrhythmic drugs) was associated with excess mortality, presumably due to drug induced proarrhythmia. It has been suggested that the degree of rate-dependent conduction slowing produced by agents that have sodium channel blocking properties may be related to the proarrhythmic propensity of these agents. In the present study, rate-dependent conduction slowing by the antidepressants amitriptyline and maprotiline was investigated in anesthetized guinea pigs.