Acceleration of the ventricular response in paroxysmal lone atrial fibrillation following the injection of adenosine.

Treatment of a patient with new onset atrial fibrillation with intravenous adenosine was followed by transient but significant acceleration of the ventricular rate. This unexpected response to adenosine can be explained by a predominating increase in sympathetic discharge relative to the drug's direct atrial ventricular nodal-blocking action.