title: Effects of ivabradine on heart rate and left ventricular function in healthy cats and cats with hypertrophic cardiomyopathy.
abstract: OBJECTIVE
  To evaluate the effects of the pacemaker funny current (I(f)) inhibitor ivabradine on heart rate (HR), left ventricular (LV) systolic and diastolic function, and left atrial performance in healthy cats and cats with hypertrophic cardiomyopathy (HCM).
  
  
  METHODS
  6 healthy cats and 6 cats with subclinical HCM.
  
  
  METHODS
  Anesthetized cats underwent cardiac catheterization and were studied over a range of hemodynamic states induced by treatment with esmolol (200 to 400 μg/kg/min, IV), esmolol and dobutamine (5 μg/kg/min, IV), ivabradine (0.3 mg/kg, IV), and ivabradine and dobutamine. Left ventricular systolic and diastolic function, cardiac output, and left atrial function were studied via catheter-based methods and echocardiography.
  
  
  RESULTS
  Treatment with ivabradine resulted in a significant reduction of HR, rate-pressure product, and LV contractile function and a significant increase in LV end-diastolic pressure, LV end-diastolic wall stress, and LV relaxation time constant (tau) in cats with HCM. Concurrent administration of ivabradine and dobutamine resulted in a significant increase of LV contractility and lusitropy, with blunted chronotropic effects of the catecholamine. Left atrial performance was not significantly altered by ivabradine in cats with HCM. Regression analysis revealed an association between maximum rate of LV pressure rise and tau in cats with HCM.
  
  
  CONCLUSIONS
  Ivabradine had significant effects on several cardiovascular variables in anesthetized cats with HCM. Studies in awake cats with HCM are needed to clinically validate these findings.
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, 43210, USA.
authors.forename: Sabine C
authors.initials: SC
authors.lastname: Riesen
authors.forename: Karsten E
authors.initials: KE
authors.lastname: Schober
authors.forename: Danielle N
authors.initials: DN
authors.lastname: Smith
authors.forename: Cristiane C
authors.initials: CC
authors.lastname: Otoni
authors.forename: Xiaobai
authors.initials: X
authors.lastname: Li
authors.forename: John D
authors.initials: JD
authors.lastname: Bonagura
mesh_terms: D058665:Adrenergic beta-1 Receptor Agonists / Q000494:pharmacology / Q000627:therapeutic use; D058671:Adrenergic beta-1 Receptor Antagonists / Q000494:pharmacology / Q000627:therapeutic use; D000818:Animals; D001552:Benzazepines / Q000494:pharmacology* / Q000627:therapeutic use; D001794:Blood Pressure / Q000187:drug effects; D002312:Cardiomyopathy, Hypertrophic / Q000188:drug therapy / Q000662:veterinary*; D002317:Cardiovascular Agents / Q000494:pharmacology / Q000627:therapeutic use*; D002371:Cat Diseases / Q000188:drug therapy*; D002415:Cats; D004280:Dobutamine / Q000494:pharmacology / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects*; D000077550:Ivabradine; D011412:Propanolamines / Q000494:pharmacology / Q000627:therapeutic use; D016277:Ventricular Function, Left / Q000187:drug effects*
chemical_list: D058665:Adrenergic beta-1 Receptor Agonists; D058671:Adrenergic beta-1 Receptor Antagonists; D001552:Benzazepines; D002317:Cardiovascular Agents; D011412:Propanolamines; D000077550:Ivabradine; D004280:Dobutamine; C036604:esmolol