title: Reproducibility of transthoracic echocardiography in small animals using clinical equipment.
abstract: OBJECTIVE
  Transthoracic echocardiography has been employed to assess left ventricular dimensions and function in small animals. The aim of this study was to identify the limits of transthoracic echocardiography in a commonly used Wistar rat model by assessing intraobserver variability, interobserver variability, and day-to-day variability of examinations implying registrations and measurements.
  
  
  METHODS
  Twenty male adult Wistar rats (body weight 496+/-52 g) were examined under volatile isoflurane anesthesia (heart rate 302+/-26 bpm) by transthoracic echocardiography (Sonos 7500; Philips) with a 15 MHz-transducer. For calculation of intraobserver variability, examinations were repeated by the same examiner and for interobserver variability, examinations were performed independently by two investigators. For day-to-day variability, examinations were repeated 14 days later. Left ventricular diameters and areas were analyzed in parasternal short axis and in a modified parasternal long axis. Fractional shortening, area shortening, ejection fraction, stroke volume, and cardiac output were calculated.
  
  
  RESULTS
  Left ventricular end-diastolic diameter was 8.9+/-0.6 mm, fractional shortening 39.0+/-5.3%, area shortening 59.6+/-6.1%, ejection fraction 83.3+/-5.1%, stroke volume 0.24+/-0.06 ml, and cardiac output 72.9+/-20.6 ml/min. Intraobserver variability of left ventricular end-diastolic diameter, fractional shortening, area shortening, and ejection fraction was less than 10%, increasing to 19% for stroke volume and cardiac output. Interobserver variability of left ventricular end-diastolic diameter, fractional shortening, area shortening, ejection fraction was less than 13%, increasing to 23% for stroke volume and 25% for cardiac output. Day-to-day variability of left ventricular end-diastolic diameter, area shortening, ejection fraction was less than 11% whereas for stroke volume it was 21% and for cardiac output it was 22%. F-ratio test comparing investigated variabilities did not reveal significant differences.
  
  
  CONCLUSIONS
  M-mode and two-dimensional echocardiography in large rats by clinically common high-end ultrasound systems can be assessed reliably. Parameters of global left ventricular performance like stroke volume and cardiac output could not be assessed with similar reliability.
authors.affiliation: 2nd Medical Clinic, Friedrich Alexander University, Erlangen-Nuremberg, University Hospital Hamburg-Eppendorf, Germany.
authors.forename: Gerald H
authors.initials: GH
authors.lastname: Wasmeier
authors.forename: Ivan
authors.initials: I
authors.lastname: Melnychenko
authors.forename: Jens-Uwe
authors.initials: JU
authors.lastname: Voigt
authors.forename: Wolfram H
authors.initials: WH
authors.lastname: Zimmermann
authors.forename: Thomas
authors.initials: T
authors.lastname: Eschenhagen
authors.forename: Nico
authors.initials: N
authors.lastname: Schineis
authors.forename: Udo
authors.initials: U
authors.lastname: Reulbach
authors.forename: Frank A
authors.initials: FA
authors.lastname: Flachskampf
authors.forename: Werner G
authors.initials: WG
authors.lastname: Daniel
authors.forename: Uwe
authors.initials: U
authors.lastname: Nixdorff
mesh_terms: D000818:Animals; D004452:Echocardiography / Q000592:standards*; D006352:Heart Ventricles / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D015203:Reproducibility of Results; D016276:Ventricular Function