title: Heart rate regularisation in patients with permanent atrial fibrillation implanted with a VVI(R) pacemaker.
abstract: Irregularity of ventricular cycles is a cause of haemodynamic impairment and symptoms in patients with atrial fibrillation (AF).
  
  
  OBJECTIVE
  Aim of the study was to determine the optimal pacing rate to stabilise ventricular cycle length at rest in patients with chronic AF, bradycardiac symptoms and VVI pacing.
  
  
  METHODS
  The compensatory pause (CP) in AF, as defined by Langendorf, was used as a reference value in pacing the heart. The spontaneous mean heart rate (MHR) was assessed with the PM OFF. The CP was then calculated with the pacing rate programmed at 40 bpm. Four pacing rates were tested: rate of the CP (RCP), RCP + 5 bpm, RCP - 5 bpm and RCP - 10 bpm.
  
  
  RESULTS
  RCP provided a good estimate of the MHR (r = 0.92). Pacing percentage (P%) was 24 +/- 15% at the pacing rate of RCP - 10 bpm, 39 +/- 19% at RCP - 5 bpm, 63 +/- 17% at RCP, and 79 +/- 19% at RCP + 5 bpm (p < 0.001). The corresponding HR modestly increased from 65 +/- 13 bpm to 66 +/- 13 bpm (p = NS), 68 +/- 13 bpm (p < 0.001) and 71 +/- 13 bpm (p < 0.001), respectively.
  
  
  CONCLUSIONS
  The RCP estimates, during pacing, what the spontaneous MHR would be. Ventricular stimulation at the RCP causes a high P%, stabilising cardiac cycles with a modest increase in HR.
authors.affiliation: Unità Operativa Cardiovascolare, Ospedale di Cecina, Azienda USL 6, Via Marrucci, 60, 57023 Cecina,(LI), Italy. gianfrancomz@tiscalinet.it
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Mazzocca
authors.forename: Tiziana
authors.initials: T
authors.lastname: Giovannini
authors.forename: Fabio
authors.initials: F
authors.lastname: Frascarelli
authors.forename: Alessandro
authors.initials: A
authors.lastname: Fabiani
authors.forename: Antonio
authors.initials: A
authors.lastname: Burali
authors.forename: Giampiero
authors.initials: G
authors.lastname: Giappichini
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Bidi
authors.forename: Daniele
authors.initials: D
authors.lastname: Bernabò
authors.forename: Enrico
authors.initials: E
authors.lastname: Manfredini
authors.forename: Giorgio
authors.initials: G
authors.lastname: Corbucci
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000503:physiopathology* / Q000628:therapy*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D008297:Male; D010138:Pacemaker, Artificial; D012146:Rest / Q000502:physiology