Propranolol-induced dysfunction of the sinus node in Wolff-Parkinson-White syndrome.

We report the findings in a patients with the Wolff-Parkinson-White syndrome (type A) who initially had recurrent fainting episodes. It appeared that they were caused by prolonged posttachycardiac depression of the sinus node, which was induced by treatment with propranolol. The possibility of covert dysfunction of the sinus node in patients with Wolff-Parkinson-White syndrome should be considered before commencing therapy with beta-adrenergic blocking agents.