title: Induced and spontaneous heart rate turbulence in mice: influence of coupling interval.
abstract: OBJECTIVE
  Heart rate turbulence (HRT) is a prognostic parameter for risk stratification in patients suffering from coronary artery disease. The aims of this study were to demonstrate the feasibility of quantifying HRT in mice, both in long-term electrocardiograms (ECGs) as well as after extrastimulus pacing, and to analyse its characteristics.
  
  
  RESULTS
  We performed long-term ECG recordings using implanted telemetric chips and electrophysiological (EP) investigations, using transvenously inserted EP catheters, in healthy mice. Heart rate turbulence was calculated using the established turbulence onset (TO) and slope (TS) algorithm. After spontaneous ventricular premature complexes (VPCs), we found a negative TO (-2.2 ± 7.5%) and positive TS (15.5 ± 18.3 ms/RR interval). Electrophysiological investigations revealed positive values for TO (0.6 ± 1.1%) and TS (6.5 ± 2.9 ms/RR interval) after extrastimulus pacing maneuvers. The shortening of the extrastimuli coupling intervals delivered during EP investigations significantly influenced TO (r = 0.57; P = 0.01): shorter coupling intervals provoked more positive TO values.
  
  
  CONCLUSIONS
  Mice display both spontaneous and induced HRT. In terms of TO, VPCs generated by extrastimulus pacing are significantly dependent on the coupling interval. Determining HRT in mice is feasible and provides insight into basic mechanisms of blood pressure regulation, which is realized by the baroreflex.
authors.affiliation: Department of Medicine-Cardiology, University Hospital Bonn, Sigmund Freud Str. 25, 53127Bonn, Germany florian.stoeckigt@ukb.uni-bonn.de.
authors.forename: Florian
authors.initials: F
authors.lastname: Stöckigt
authors.affiliation: Department of Medicine-Cardiology, University Hospital Bonn, Sigmund Freud Str. 25, 53127Bonn, Germany.
authors.forename: Sonja
authors.initials: S
authors.lastname: Pöhlmann
authors.affiliation: Department of Medicine-Cardiology, University Hospital Bonn, Sigmund Freud Str. 25, 53127Bonn, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Nickenig
authors.affiliation: Department of Medicine-Cardiology, University Hospital Bonn, Sigmund Freud Str. 25, 53127Bonn, Germany.
authors.forename: Jörg Otto
authors.initials: JO
authors.lastname: Schwab
authors.affiliation: Department of Medicine-Cardiology, University Hospital Bonn, Sigmund Freud Str. 25, 53127Bonn, Germany.
authors.forename: Jan Wilko
authors.initials: JW
authors.lastname: Schrickel
mesh_terms: D000465:Algorithms; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D017704:Baroreflex; D001794:Blood Pressure; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D004195:Disease Models, Animal; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005240:Feasibility Studies; D006339:Heart Rate; D008810:Mice, Inbred C57BL; D011237:Predictive Value of Tests; D012815:Signal Processing, Computer-Assisted; D013686:Telemetry; D013997:Time Factors; D018879:Ventricular Premature Complexes / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology
keywords: Baroreflex; Electrophysiological investigation; Heart rate turbulence; Long-term ECG recording; Mice