Enhanced accessory pathway conduction following intravenous amiodarone in atrial fibrillation. A case report.

We observed a dangerous increase of ventricular rate following the intravenous administration of amiodarone in a patient with atrial fibrillation and rapid ventricular response associated with the Wolff-Parkinson-White syndrome. The mechanism of enhanced accessory pathway conduction remains speculative. A possible explanation for the shortened antegrade effective refractory period of the accessory pathway is afforded by the hypotensive action of amiodarone or its dissolvent which might trigger beta-adrenergic reflexes. Intravenous amiodarone should be used with caution in patients with atrial fibrillation and rapid ventricular response via an accessory pathway.