Functional properties of accessory atrioventricular pathways in Wolff-Parkinson-White syndrome. Clinical implications

The Wolff-Parkinson-White syndrome is an uncommon cardiac disorder due to the presence of an accessory atrioventricular pathway resulting in ventricular pre-excitation and supraventricular tachycardias. The recognition of the Wolff-Parkinson-White syndrome is important because of the potential for the development of extremely rapid ventricular rates during atrial fibrillation that may lead to ventricular fibrillation and sudden death. The diagnosis of the Wolff-Parkinson-White syndrome is obvious when classic delta waves and short P-R intervals are present, but the electrocardiographic manifestations of the syndrome may be subtle and vary considerably from patient to patient. Certain commonly used antiarrhythmic medications may be useful for the treatment of reciprocating tachycardia in these patients and yet prove to be ineffective--or even deleterious--in preventing excessively rapid conduction to the ventricles during atrial fibrillation. An appreciation of the functional properties of the accessory pathways in the Wolff-Parkinson-White syndrome and how they are affected by pharmacologic agents should result in improved recognition of this entity and more effective medical management of patients with a risk of sudden death.