title: Tidal volume and minute ventilation parameters derived from pacemaker impedance measurements can predict experimental heart failure development.
abstract: BACKGROUND
  Specific respiratory patterns and periodic breathing have been associated with heart failure. Less is known regarding changes in tidal volume (TV) and minute ventilation (MV) as a result of early heart failure (HF) decompensation.
  
  
  RESULTS
  Twelve adult Yucatan minipigs were implanted with a biventricular pacemaker and a left ventricular pressure sensor. HF was induced using high-rate pacing at 240 paces per minute for 2-4 weeks, followed by 2 weeks of recovery. Left ventricular pressure measurements and weekly echocardiograms verified the development of HF. The right and left ventricular intrathoracic impedance (RVITI and LVITI, respectively) signals were used to determine the respiratory parameters of rate, TV, and MV. Compared to baseline (BL), during HF, the TV dropped 68% for RVITI and 61% for LVITI (P < 0.0001 for both). Correspondingly, MV dropped 34% for RVITI and 27% for LVITI (P < 0.0001 for both). The daily medians of the respiratory rate (RR) and the longest breath interval (LBI) did not change significantly from BL to HF and recovery. However, circadian variation of the RR and the LBI became blunted during HF development. All derived respiratory parameters showed the reverse trend during the recovery period.
  
  
  CONCLUSIONS
  TV and MV change independently from the RR in early HF decompensation. Tracking the changes of TV and MV with an implantable device may provide an additional method for early HF detection and assessment of the response to therapy.
authors.affiliation: Micro Systems Engineering, Inc, Lake Oswego, Oregon.
authors.forename: Sharon
authors.initials: S
authors.lastname: Lefkov
authors.forename: Chris
authors.initials: C
authors.lastname: de Voir
authors.forename: Dirk
authors.initials: D
authors.lastname: Müssig
authors.forename: Tengiz
authors.initials: T
authors.lastname: Tkebuchava
authors.forename: Jie
authors.initials: J
authors.lastname: Lian
authors.forename: Michael V
authors.initials: MV
authors.lastname: Orlov
mesh_terms: D000818:Animals; D058266:Dielectric Spectroscopy / Q000295:instrumentation* / Q000379:methods*; D006333:Heart Failure / Q000175:diagnosis* / Q000503:physiopathology*; D006801:Humans; D010138:Pacemaker, Artificial; D012123:Pulmonary Ventilation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013552:Swine; D013556:Swine, Miniature; D013990:Tidal Volume
keywords: biventricular pacing; cardiac resynchronization; heart failure; respiration