title: Pacemaker repetitive nonreentrant ventriculoatrial synchrony. Why did automatic mode switching occur?
abstract: Repetitive nonreentrant ventriculoatrial synchrony during dual-chamber pacing is characterized by long intervals alternating with short intervals. This arrangement activated automatic mode switching in a St Jude dual-chamber pacemaker in which the algorithm requires an atrial sensed event for automatic mode switching initiation. Automatic mode switching activation by an atrial sensed event (retrograde P wave) was puzzling because the programmed postventricular atrial period was longer than the retrograde ventriculoatrial conduction time. The explanation is presented in the form of questions and answers to facilitate the understanding of pacemaker function and complex timing cycles.
authors.affiliation: Florida Heart Rhythm Institute, Tampa, FL. Electronic address: ssbarold@aol.com.
authors.forename: S Serge
authors.initials: SS
authors.lastname: Barold
authors.affiliation: Heart Center, University Hospital of Ghent, Ghent, Belgium.
authors.forename: Roland X
authors.initials: RX
authors.lastname: Stroobandt
authors.affiliation: Heart Center, University Hospital of Ghent, Ghent, Belgium.
authors.forename: Frederic
authors.initials: F
authors.lastname: Van Heuverswyn
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial; D004562:Electrocardiography; D006329:Heart Conduction System / Q000503:physiopathology*; D006339:Heart Rate; D006801:Humans; D008297:Male; D010138:Pacemaker, Artificial; D012804:Sick Sinus Syndrome / Q000503:physiopathology / Q000628:therapy*