title: Reducing ventricular pacing in sinus node dysfunction.
abstract: BACKGROUND
  The use of DDIR mode has been limited since the advent of mode switch in the DDDR mode. In patients with AV block, DDDR is necessary to maintain AV synchrony. However, DDIR mode may still be beneficial for patients with intact AV conduction. The aim of this study was to compare the incidence of ventricular pacing and atrial tachyarrhythmia in DDIR and DDDR with mode switch in a randomized, single-blind, crossover study, and discuss the utility of both modes.
  
  
  RESULTS
  Twenty-four patients (8 males) with bradycardia-tachycardia syndrome and no signs of AV block (mean age 70.1 +/- -9.1 years) were enrolled and randomized to DDIR or DDDR modes with the leads placed at the right atrial appendage and right ventricular apex. After 12 weeks, patients were switched to the opposite mode. During the study period, atrial high rate episodes and other pacemaker diagnostic data were collected. Significantly less ventricular pacing was observed in DDIR mode (DDIR versus DDDR; 48.9%, 76.5%, P = 0.0002) and atrial high rate episodes were significantly lower in DDIR mode (DDIR versus DDDR; 1.32, 1.85 per day, P < 0.05).
  
  
  CONCLUSIONS
  In patients with sinus node dysfunction and intact AV conduction, DDIR mode may have important implications for simplifying device programming, device longevity, and to avoid atrial tachyarrhythmia.
authors.affiliation: Second Department of Internal Medicine, Yokohama City University Hospital, Yokohama.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Ishikawa
authors.forename: Shinichi
authors.initials: S
authors.lastname: Sumita
authors.forename: Masami
authors.initials: M
authors.lastname: Kosuge
authors.forename: Chad
authors.initials: C
authors.lastname: Giese
authors.forename: Toby
authors.initials: T
authors.lastname: Markowitz
authors.forename: Soichi
authors.initials: S
authors.lastname: Tsunoda
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Uchino
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Kohei
authors.initials: K
authors.lastname: Matsushita
authors.forename: Noriko
authors.initials: N
authors.lastname: Inoue
authors.forename: Katsumi
authors.initials: K
authors.lastname: Matsushita
authors.forename: Minoru
authors.initials: M
authors.lastname: Taima
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kimura
authors.forename: Satoshi
authors.initials: S
authors.lastname: Umemura
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001146:Arrhythmia, Sinus / Q000503:physiopathology / Q000628:therapy*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D018592:Cross-Over Studies; D018450:Disease Progression; D015716:Electrocardiography, Ambulatory; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology*; D006352:Heart Ventricles; D006801:Humans; D008297:Male; D008875:Middle Aged; D016037:Single-Blind Method; D012849:Sinoatrial Node / Q000503:physiopathology*; D016896:Treatment Outcome