AjmaTine, an alkaloid which contains the quinuclidine ring, is closely related to quinidine; in quinidine, the quinuclidine ring is joined to quinoline, while in ajmaline, which is derived from a species of Rauwolfia, it is combined with the reputedly less toxic indole nucleus. Ajmaline was administered by slow intravenous drip to patients with chronic, sustained atrial fibrillation, some of whom also had frequent premature ventricular sY5toles. Small doses of ajmaline eliminated the premature ventricular systoles although the atrial arrhythmia persisted. Larger doses of ajmaline restored normal P wave activity, but complete A-V block developed.When A-V block was prevented by small doses of procaine amide, ajmaline converted atrial fibrillation to regular sinus rhythm for short periods.