© 2003 by European Society of Cardiology
Mode switching failure during atrial flutter: the ‘2:1 lock-in’ phenomenon
Cardiovascular Centre Aalst, OLV Ziekenhuis Moorselbaan 164, Aalst, 9300, Belgium
AIMS: To evaluate incidence and mechanism of a special form of automatic mode switching (MS) failure in patients with atrial flutter.
METHODS AND RESULTS: Retrospectively the charts of 134 patients implanted with dual chamber pacemakers with MS algorithms were reviewed. Seven patients (5.2%) were identified that presented with sustained rapid ventricular pacing resulting from atrial flutter with failure of automatic MS. Since this form of MS failure implies 2:1 tracking of atrial flutter, it was coined ‘2:1 lock-in’. A theoretical timing model was developed to clarify the mechanism of this special form of MS failure. Prerequisites for the ‘2:1 lock-in’ phenomenon are: (1) the sum of the AV delay and the post ventricular blanking (PVAB) must be longer than the cycle length of the atrial flutter, (2) the tachycardia detection rate must be higher than half the atrial flutter rate and (3) the maximum tracking rate (MTR) must be higher than half the atrial flutter rate. Recommendations for programming in order to avoid this specific form of MS failure are made accordingly and parallel algorithms for flutter detection are discussed.
CONCLUSION: ‘2:1 lock-in’ is a typical form of MS failure in patients with atrial flutter and the mechanism is closely linked to the typical atrial sensing windows.
Key Words: Mode switching failure, atrial flutter, dual chamber pacemakers
Correspondence: Marc A. Goethals, Cardiovascular Centre, OLV Ziekenhuis Aalst, Moorselbaan 164, 9300 Aalst, Belgium. Tel.: 32 53 724439; Fax: 32 53 724185; E-mail: marc.goethals{at}olvz-aalst.be
[1] Barold SS and Mond HG. Fallback response of dual chamber (DDD and DDDR) pacemakers: a proposed classification. Pacing Clin Electrophysiol 1994; 17: 1160–1165.[Medline]
[2] Ellenbogen KA, Mond HG, Wood MA, et al. Failure of automatic mode switching: recognition and management. Pacing Clin Electrophysiol 1997; 20: 268–275.[Medline]
[3] Den Dulk K. Automatic mode switching in DDDR pacemakers. In Oto AM (Ed.). Practice and Progress in Cardiac Pacing and Electrophysiology 1996; Kluwer Academic Publishers pp. 151–160.
[4] Palma EC, Kedarnath V, Vankawalla V, et al. Effect of varying atrial sensitivity, AV interval, and detection algorithm on automatic mode switching. Pacing Clin Electrophysiol 1996; 19: 1734–1739.
[5] Leung SK, Lau CP, Tse-Fun Lam C, et al. Is automatic mode switching effective for atrial arrhythmias occurring at different rates? A study of the efficacy of automatic mode and rate switching to simulated atrial arrhythmias by chest wall stimulation. Pacing Clin Electrophysiol 2000; 23: 824–831.[Medline]
[6] Johnson NJ. Inconsistent response to rapid atrial rhythms in a DDD pacemaker with the fallback feature. Pacing Clin Electrophysiol 1995; 18: 1458–1462.[Medline]
[7] Israel CW. Analysis of mode switching algorithms in dual chamber pacemakers. Pacing Clin Electrophysiol 2002; 25: 380–393.[Medline]
[8] Brandt J, Fåhraeus T, Schüller H. Far-field QRS complex sensing via the atrial pacemaker lead. II. Prevalence, clinical significance and possibility of intraoperative prediction in DDD pacing. Pacing Clin Electrophysiol 1988; 11: 1540–1544.[Medline]
[9] Fröhlig G, Helwani Z, Kusch O, et al. Bipolar ventricular far-field signals in the atrium. Pacing Clin Electrophysiol 1999; 22: 1604–1613.[Medline]
[10] Brandt J and Worzewski W. Far-field QRS complex sensing: prevalence and timing with bipolar atrial sensing atrial leads. Pacing Clin Electrophysiol 2000; 23: 315–320.[Medline]
[11] Lazarus A. Far-field R wave sensing. Prog Biomed Res 1998; 4: 229–231.
[12] Cools F, Van Twembeke R, Hemelhof H, et al. Feasibility of using atrial sensitivities below 0.5 mV in a DDD(R) pacemaker with mode switching algorithm. Prog Biomed Res 1999; 3: 303–306.
[13] Sutton R, Stack Z, Bruls A, et al. Tiered management of atrial arrhythmias: The Pulsar MaxTM family of pacemakers. Herzschr Elektrophys 1999; 10:Suppl. 1, 1/8–1/14.
CiteULike 
Connotea 
Del.icio.us What's this?
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||