title: Automatic mode switching of implantable pacemakers: II. Clinical performance of current algorithms and their programming.
abstract: While the hemodynamic and clinical significance of automatic mode switching (AMS) in patients with pacemakers has been demonstrated, the clinical behavior of AMS algorithms differ widely according to the manufacturers and pacemaker models. In general, a "rate-cutoff" detection method of atrial tachyarrhythmias provides a rapid AMS onset and resynchronization to sinus rhythm at the termination of atrial tachyarrhythmias, but may cause intermittent oscillations between the atrial tracking and AMS mode. This can be minimized with a "counter" of total number of high rate events before the AMS occurs. The use of a "running average" algorithm results in more stable rate control during AMS by reducing the incidence of oscillations, but at the expense of delayed AMS onset and resynchronization to sinus rhythm. Algorithms may be combined to fine tune the AMS response and to avoid rapid fluctuation in pacing rate. Appropriate programming of atrial sensitivity, and the avoidance of ventriculoatrial cross-talk are essential for optimal AMS performance.
authors.affiliation: Department of Medicine, Queen Mary Hospital, and the Institute of Cardiovascular Science and Medicine, Faculty of Medicine, University of Hong Kong, Hong Kong. cplau@hkucc.hku.hk
authors.forename: Chu-Pak
authors.initials: CP
authors.lastname: Lau
authors.forename: Sum-Kin
authors.initials: SK
authors.lastname: Leung
authors.forename: Hung-Fat
authors.initials: HF
authors.lastname: Tse
authors.forename: S Serge
authors.initials: SS
authors.lastname: Barold
mesh_terms: D000465:Algorithms; D001281:Atrial Fibrillation / Q000503:physiopathology / Q000517:prevention & control*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D004594:Electrophysiology; D006801:Humans; D010138:Pacemaker, Artificial