title: Autonomic function during closed loop stimulation and fixed rate pacing: heart rate variability analysis from 24-hour Holter recordings.
abstract: OBJECTIVE
  Aim of this retrospective study was to analyze the effect of closed-loop stimulation (CLS) and DDD pacing mode on autonomic balance, and to evaluate heart rate variability (HRV) during CLS stimulation.
  
  
  METHODS
  Autonomic balance was estimated by a 24-hour HRV analysis of paced and spontaneous beats in patients implanted with a dual-chamber pacemaker (Inos(2+) CLS-Biotronik GmbH, Berlin, Germany) and randomly assigned to CLS or DDD pacing mode. Patients underwent two 24-hour electrocardiogram Holter recordings at the end of each 3-month pacing mode period. Each Holter recording was automatically scanned to extract sequences of consecutive beats of the same type [atrial paced (Ap)-sequence and atrial spontaneous (As)-sequence], lasting at least 130 beats.
  
  
  RESULTS
  Eight hundred and ten sequences were extracted from 15 patients, and the following spectral parameters were evaluated during both CLS and DDD mode: the total power (variance), the absolute and percentage (relative to the total power) powers of the low frequency (LF, 0.04-0.15 Hz) and high frequency (HF, 0.15-0.4 Hz) components, as well as the LF/HF power ratio.
  
  
  CONCLUSIONS
  The two main findings of this study were: in all the patients, CLS seems to mimic short-term physiological HRV, although the variability (total power) was lower than that relative to the spontaneous beats; the HRV of the spontaneous beats had an higher LF/HF when the pacemaker was programmed as DDD respect to CLS, consistent with a shift toward sympathetic predominance.
authors.affiliation: Istituto del Cuore e dei Grossi Vasi "Attilio Reale," 1a Facoltà di Medicina e Chirurgia, Università di Roma "La Sapienza," Rome, Italy.
authors.forename: Raffaele
authors.initials: R
authors.lastname: Quaglione
authors.forename: Giovanni
authors.initials: G
authors.lastname: Calcagnini
authors.forename: Federica
authors.initials: F
authors.lastname: Censi
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Piccirilli
authors.forename: Luca
authors.initials: L
authors.lastname: Iannucci
authors.forename: Marco
authors.initials: M
authors.lastname: Raveggi
authors.forename: Gianluca
authors.initials: G
authors.lastname: Biancalana
authors.forename: Pietro
authors.initials: P
authors.lastname: Bartolini
mesh_terms: D000368:Aged; D001341:Autonomic Nervous System / Q000502:physiology*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D018592:Cross-Over Studies; D015716:Electrocardiography, Ambulatory; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial; D012189:Retrospective Studies; D012815:Signal Processing, Computer-Assisted; D018709:Statistics, Nonparametric