Effects of Ouabain, Atropine, and Ouabain and Atropine, on A-V Nodal Conduction in Man

The prolongation of A-V transmission time that occurs with increasing rates of right atrial pacing has been used to study the effect of ouabain and of ouabain plus atropine on A-V nodal conduction in 14 patients with normal A-V nodes. Drugs were injected into the superior vena cava or pulmonary artery over a 1- to 2-min period. Atropine in a dose of 0.02 mg/kg shortened A-V conduction time by an average of 0.112 sec; ouabain alone in a dose of 0.01 mg/kg lengthened A-V conduction time by 0.053 sec. Ouabain given after large doses of atropine did not prolong A-V conduction at any paced rate. Thus, in these resting patients with normal A-V nodal function, usual digitalizing dosages of ouabain did not have an extravagal or antiadrenergic effect on A-V nodal conduction.