title: Demonstration of phase-3 and phase-4 retrograde block in a second concealed accessory pathway after an initial successful radiofrequency ablation of a 'normal' concealed accessory pathway.
abstract: We report a patient with concealed Wolff-Parkinson-White syndrome who, following catheter ablation, demonstrated phase-3 and phase-4 retrograde block in a concealed accessory pathway. After an initial 'apparently successful' ablation, retrograde conduction was through the atrioventricular node during constant ventricular pacing. Ventricular extrastimulus testing was performed at a basic drive cycle length of 600 ms. Unexpectedly, ventricular extrastimuli at coupling intervals of 440-380 ms were conducted retrogradely over an accessory pathway, consistent with a phase-3 and phase-4 retrograde block in the accessory pathway. Residual accessory pathway conduction was eliminated in a single ablation session.
authors.affiliation: Department of Allied Health Sciences, Tokyo Medical and Dental University School of Medicine, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Azegami
authors.forename: F
authors.initials: F
authors.lastname: Suzuki
authors.forename: M
authors.initials: M
authors.lastname: Kurabayashi
authors.forename: T
authors.initials: T
authors.lastname: Horikawa
authors.forename: H
authors.initials: H
authors.lastname: Ashikawa
authors.forename: K
authors.initials: K
authors.lastname: Motokawa
authors.forename: T
authors.initials: T
authors.lastname: Kawara
authors.forename: K
authors.initials: K
authors.lastname: Hiejima
mesh_terms: D017115:Catheter Ablation; D004562:Electrocardiography; D006327:Heart Block / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D014927:Wolff-Parkinson-White Syndrome / Q000503:physiopathology / Q000601:surgery