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Pacing‐Induced Alternate Wenckebach Periods: Incidence and Clinical Significance
Author(s) -
LÉVY SAMUEL,
POUGET BERTRAND,
CLEMENTY JACQUES,
BEMURAT MARC,
BRICAUD HENRI
Publication year - 1979
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1111/j.1540-8159.1979.tb04281.x
Subject(s) - medicine , incidence (geometry) , clinical significance , cardiology , optics , physics
Alternate Wenckebach periods have been defined as episodes of 2:1 atrioventricular (AV) block in which conducted P waves exhibit progressive JH prolongation until two or three successively blocked P waves. Ocurrence of this phenomenon during atrial pacing has been established. 7'xshirty‐six patients were studied and right atrial pacing was achieved at increasing rates up to 350 beats/min in order to induce alternate Wenckebach periods. His bundle recordings were obtained in every patient. The patients were subdivided into three groups according to the AV nodni conduction time (AH interval): normal AH (75‐130 ms) was present in 15 patients, short AH (70 ms) in 13 patients and prolonged AH (130 ms) in eight patients. Alternate Wenckebach periods were observed in 29 patients (80.5%). In every patient alternate Wenckebach periods occurred at the AV node level. Atrial pacing failed to induce alternate Wenckebach periods in seven patients, six of whom belonged to the short AH group. In four patients 3:1 block never appeared because of block at the atrial level. Two patients presented 2:1 and 3:1 intrahissian block without significant AH prolongation. The remaining patient developed atrial fibrillation. Alternate Wenckebach periods were observed in six of nine patients after intravenous atropine. This study suggests: 1. pacing‐induced alternate Wenckebach periods at the AV node level are a physiologic phenomenon; and 2. total or partial bypass (or accelerated A V conduction) atrial refractoriness or vulnerability or block at a lower level may prevent its occurrence.