Effects of commonly used cardioactive drugs on atrial and sinoatrial conduction in man.
Atrial and sinoatrial conduction intervals were measured in patients before and after the intravenous administration of one of four cardioactive drugs: procainamide, atropine, ouabain, and propranolol. Procainamide uniformly prolonged atrial conduction and shortened sinoatrial conduction. Atropine also shortened sinoatrial conduction but did not significantly alter atrial conduction. Ouabain prolonged sinoatrial conduction in patients with normal control sinoatrial conduction intervals and did not affect atrial conduction. Propranolol did not significantly alter sinoartrial conduction and only prolonged interatrial conduction in patients with normal base line atrial conduction intervals. Of the cardioactive drugs tested, only procainamide and propranolol significantly altered the atrial conduction intervals; furthermore, the effects of these cardioactive drugs on sinoatrial conduction were disparate from their effects on atrial conduction.