title: Linking: a mechanism of intermittent preexcitation in the Wolff-Parkinson-White syndrome.
abstract: Intermittent preexcitation in the Wolff-Parkinson-White syndrome has been equated with a long accessory pathway refractory period and long R-R interval between preexcited beats in atrial fibrillation and therefore a low risk for sudden death. A case of Wolff-Parkinson-White syndrome in which preexcitation became intermittent following procainamide infusion, with only moderate prolongation of the accessory pathway refractory period but marked prolongation of the shortest preexcited R-R interval in atrial fibrillation, is described. Programmed ventricular and atrial stimulation demonstrated that intermittent preexcitation was caused by concealed conduction producing a linking phenomenon, facilitated by the antiarrhythmic drug. Linking due to concealed retrograde penetration of a propagated impulse into the accessory pathway may contribute to the disparity between accessory pathway refractory period and shortest preexcited R-R interval in atrial fibrillation in some patients and may be a confounding factor in the interpretation of noninvasive tests of accessory pathway conduction.
authors.affiliation: Department of Medicine, UCLA School of Medicine 90024-1679.
authors.forename: H R
authors.initials: HR
authors.lastname: Middlekauff
authors.forename: W G
authors.initials: WG
authors.lastname: Stevenson
authors.forename: T S
authors.initials: TS
authors.lastname: Klitzner
mesh_terms: D000293:Adolescent; D002304:Cardiac Pacing, Artificial; D004562:Electrocardiography; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D014927:Wolff-Parkinson-White Syndrome / Q000503:physiopathology*