Cardioversion with lidocaine of vagally associated atrial fibrillation in two dogs.

Two dogs with acute onset atrial fibrillation (AF) were cardioverted to sinus rhythm by the administration of 2mg/kg lidocaine given intravenously. Each dog was believed to have AF initiated because of elevated vagal tone. This report has potential clinical impact for a subset of dogs because it offers a treatment to circumvent persistent AF. Furthermore, this encouraging result of a pharmacologic cardioversion suggests that further investigation would be of interest to ascertain the effectiveness and mechanism of the antiarrhythmic action of lidocaine in vagally induced AF.