Development of rapid atrial fibrillation with a wide QRS complex after neostigmine in a patient with intermittent Wolff-Parkinson-White syndrome.

We report the case of a 67-yr-old man with intermittent Wolff-Parkinson-White (WPW) syndrome in whom neostigmine produced life-threatening tachyarrhythmias. The patient was scheduled for microsurgery for a laryngeal tumour. When he arrived in the operating room, the electrocardiogram showed normal sinus rhythm with a rate of 82 beat min-1 and a narrow QRS complex which remained normal throughout the operative period. On emergence from anaesthesia, the sinus rhythm (87 beat min-1) changed to atrial fibrillation with a rate of 80-120 beat min-1 and a normal QRS complex. We did not treat the atrial fibrillation because the patient was haemodynamically stable. Neostigmine 1 mg without atropine was then administered to antagonize residual neuromuscular block produced by vecuronium. Two minutes later, the narrow QRS complexes changed to a wide QRS complex tachycardia with a rate of 110-180 beat min-1, which was diagnosed as rapid atrial fibrillation. As the patient was hypotensive, two synchronized DC cardioversions of 100 J and 200 J were given, which restored sinus rhythm. No electrophysiological studies of anticholinesterase drugs have been performed in patients with WPW syndrome. We discuss the use of these drugs in this condition.