Intermittent Wolff-Parkinson-White syndrome due to phase 3 and phase 4 block: disappearance of rapid ventricular response during atrial fibrillation.
A 65-year-old man with Wolff-Parkinson-White syndrome type A had a rapid ventricular response over an accessory pathway during atrial fibrillation. Four months later, electrophysiological study revealed the following properties: 1) The antegrade accessory pathway conduction showed phase 3 and phase 4 block. 2) The retrograde concealed accessory pathway conduction eliminated phase 4 block in the antegrade accessory pathway conduction. 3) Premature ventricular excitation arose from the accessory pathway or from the ventricular muscle close to its distal end. 4) Atrial fibrillation during isoproterenol infusion did not show rapid ventricular response. Spontaneous impairment of accessory pathway conduction due to phase 3 and phase 4 block was suspected.
Fujiki
A
A
Second Department of Internal Medicine, Toyama Medical and Pharmaceutical University, Japan.
Yoshida
S
S
Tani
M
M
Sasayama
S
S
D000368:Aged; D001281:Atrial Fibrillation / Q000503:physiopathology*; D002304:Cardiac Pacing, Artificial; D004562:Electrocardiography; D006327:Heart Block / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D006329:Heart Conduction System / Q000503:physiopathology; D006352:Heart Ventricles / Q000187:drug effects / Q000503:physiopathology; D006801:Humans; D007545:Isoproterenol; D008297:Male; D014927:Wolff-Parkinson-White Syndrome / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology
D007545:Isoproterenol