title: Echocardiographic assessment of right ventricular systolic function in conscious healthy dogs following a single dose of pimobendan versus atenolol.
abstract: OBJECTIVE
  To quantify drug-induced changes in right ventricular (RV) systolic function after administration of pimobendan and atenolol.
  
  
  METHODS
  80 healthy privately-owned dogs.
  
  
  METHODS
  Using a prospective, blinded, fully-crossed study design with randomized drug administration, RV systolic function was determined twice at two time periods; before and 3 h after administration of pimobendan (0.25 mg/kg PO) or atenolol (1 mg/kg PO). Indices of RV systolic function included tricuspid annular plane systolic excursion (TAPSE), fractional area change (FAC), pulsed-wave tissue Doppler-derived systolic myocardial velocity of the lateral tricuspid annulus (S'), and speckle-tracking-derived global longitudinal RV free wall strain and strain rate. The effect of treatment on percent change from baseline RV function was analyzed with a linear mixed model including the covariates heart rate, body weight, age, gender, drug sequence, and time period.
  
  
  RESULTS
  All indices showed a significant (p < 0.0001) increase and decrease from baseline following pimobendan and atenolol, respectively. Significant differences from baseline were attributed to drug treatment (p < 0.0001); whereas, effects of other covariates were not significant. The greatest percent changes, but also highest variability, were observed for S' and strain rate (p < 0.0001). Post-atenolol, a significantly greater proportion of dogs exceeded the repeatability coefficient of variation for FAC and S' compared to TAPSE (p ≤ 0.007).
  
  
  CONCLUSIONS
  Echocardiographic indices in healthy dogs tracked expected changes in RV systolic function following pimobendan and atenolol and warrant study in dogs with cardiovascular disease.
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, 601 Vernon Tharp Street, Columbus, OH 43210, USA.
authors.forename: Lance C
authors.initials: LC
authors.lastname: Visser
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, 601 Vernon Tharp Street, Columbus, OH 43210, USA. Electronic address: scansen.2@osu.edu.
authors.forename: Brian A
authors.initials: BA
authors.lastname: Scansen
authors.affiliation: Department of Biomedical Informatics, The Ohio State University, 2012 Kenny Road, Columbus, OH 43221, USA.
authors.forename: Nicole V
authors.initials: NV
authors.lastname: Brown
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, 601 Vernon Tharp Street, Columbus, OH 43210, USA.
authors.forename: Karsten E
authors.initials: KE
authors.lastname: Schober
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, 601 Vernon Tharp Street, Columbus, OH 43210, USA.
authors.forename: John D
authors.initials: JD
authors.lastname: Bonagura
mesh_terms: D058671:Adrenergic beta-1 Receptor Antagonists / Q000494:pharmacology; D000818:Animals; D001262:Atenolol / Q000494:pharmacology*; D002316:Cardiotonic Agents / Q000494:pharmacology; D018592:Cross-Over Studies; D004285:Dogs / Q000502:physiology*; D011724:Pyridazines / Q000494:pharmacology*; D014261:Tricuspid Valve / Q000000981:diagnostic imaging / Q000187:drug effects*; D014463:Ultrasonography; D016278:Ventricular Function, Right / Q000187:drug effects* / Q000502:physiology
chemical_list: D058671:Adrenergic beta-1 Receptor Antagonists; D002316:Cardiotonic Agents; D011724:Pyridazines; C041648:pimobendan; D001262:Atenolol
keywords: Canine; Cardiac; Echocardiography; Ultrasound