title: The use of strain, strain rate, and displacement by 2D speckle tracking for assessment of systolic left ventricular function in goats: applicability and influence of general anesthesia.
abstract: BACKGROUND
  Assessment of left ventricular (LV) systolic function can be achieved by conventional echocardiographic methods, but quantification of contractility, regional myocardial function, and ventricular synchrony is challenging. The goal of this study was to investigate the applicability of two-dimensional speckle tracking (2DST) to characterize segmental and global wall motion for assessment of LV function and LV synchrony in healthy goats. We aimed to describe the techniques, report normal values of a variety of 2DST indices, and determine the influence of general anesthesia.
  
  
  METHODS
  Prospective study on 22 healthy female Saanen goats (3.7 ± 1.1 y, 60.2 ± 10.5 kg [mean ± SD]). All goats underwent two transthoracic echocardiographic examinations, the first standing and unsedated and the second 7.4 ± 3.5 days later during isoflurane anesthesia and positioned in sternal recumbency. Data analyses were performed offline, blinded, and in random order. Left ventricular longitudinal, radial and circumferential strain and strain rate as well as longitudinal and radial displacement were measured using 2DST methods. Summary statistics were generated and differences of 2DST variables between myocardial segments and treatments (i.e., awake vs. anesthetized) were assessed statistically (alpha level=0.05).
  
  
  RESULTS
  Echocardiographic analyses by 2DST were feasible in all goats and at both time points. Longitudinal systolic strain, strain rate and displacement followed a gradient from apex to base. Absolute systolic strain was generally lower and strain rate was higher in awake goats compared to anesthetized goats. Circumferential and radial indices did not consistently follow a segmental pattern. Generally, peak strain occurred later in anesthetized goats compared to awake goats. General anesthesia did not significantly influence LV synchrony.
  
  
  CONCLUSIONS
  2SDT is a valid method for non-invasive characterization of LV wall motion in awake and anesthetized goats. The results of this study add to the understanding of LV mechanical function, aid in the diagnosis of global and segmental LV systolic dysfunction, and will be useful for future cardiovascular studies in this species. However, effects of anesthesia and species-specific characteristics should be considered when goats are used as animal models for human disease.
authors.affiliation: Equine Department, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, Zurich, 8057, Switzerland. annaberli@hotmail.com.
authors.forename: Ann-Sabin J
authors.initials: AS
authors.lastname: Berli
authors.affiliation: Small Animal Department, and Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, Zurich, 8057, Switzerland. rjud@vetclinics.uzh.ch.
authors.forename: Rahel
authors.initials: R
authors.lastname: Jud Schefer
authors.affiliation: Farm Animal Department, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, Zurich, 8057, Switzerland. kathrin.steininger@web.de.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Steininger
authors.affiliation: Equine Department, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, Zurich, 8057, Switzerland. cschwarzwald@vetclinics.uzh.ch.
authors.forename: Colin C
authors.initials: CC
authors.lastname: Schwarzwald
mesh_terms: D000768:Anesthesia, General; D018681:Anesthetics, General / Q000494:pharmacology*; D000818:Animals; D004452:Echocardiography / Q000379:methods*; D055119:Elastic Modulus / Q000187:drug effects / Q000502:physiology; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006041:Goats; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D009068:Movement / Q000187:drug effects / Q000502:physiology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D033081:Shear Strength / Q000187:drug effects / Q000502:physiology; D013318:Stroke Volume / Q000187:drug effects / Q000502:physiology; D013718:Tensile Strength / Q000187:drug effects / Q000502:physiology; D016277:Ventricular Function, Left / Q000187:drug effects / Q000502:physiology*; D014783:Viscosity / Q000187:drug effects
chemical_list: D018681:Anesthetics, General