title: Evaluation of a technique to measure heart rate variability in anaesthetised cats.
abstract: Analysis of heart rate (HR) and heart rate variability (HRV) are powerful tools to investigate cardiac diseases, but current methods, including 24-h Holter monitoring, can be cumbersome and may be compromised by movement artefact. A commercially available data capture and analysis system was used in anaesthetised healthy cats to measure HR and HRV during pharmacological manipulation of HR. Seven healthy cats were subjected to a randomised crossover study design with a 7 day washout period between two treatment groups, placebo and atenolol (1mg/kg, IV), with the efficacy of atenolol to inhibit β1 adrenoreceptors challenged by epinephrine. Statistical significance for the epinephrine challenge was set at P<0.0027 (Holm-Bonferroni correction), whereas a level of significance of P<0.05 was set for other variables. Analysis of the continuous electrocardiography (ECG) recordings showed that epinephrine challenge increased HR in the placebo group (P=0.0003) but not in the atenolol group. The change in HR was greater in the placebo group than in the atenolol group (P=0.0004). Therefore, compared to cats pre-treated with placebo, pre-treatment with atenolol significantly antagonised the tachycardia while not significantly affecting HRV. The increased HR in the placebo group following epinephrine challenge was consistent with a shift of the sympathovagal balance towards a predominantly sympathetic tone. However, the small (but not significant at the critical value) decrease in the normalised high-frequency component (HFnorm) in both groups of cats suggested that epinephrine induced a parasympathetic withdrawal in addition to sympathetic enhancement (increased normalised low frequency component or LFnorm). In conclusion, this model is a highly sensitive and repeatable model to investigate HRV in anaesthetised cats that would be useful in the laboratory setting for short-term investigation of cardiovascular disease and subtle responses to pharmacological agents in this species.
authors: School of Veterinary Science, The University of Queensland, Gatton Campus, QLD 4343, Australia; Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
authors: Kuan Hua
authors: KH
authors: Khor
authors: School of Veterinary Science, The University of Queensland, Gatton Campus, QLD 4343, Australia.
authors: Ian A
authors: IA
authors: Shiels
authors: School of Veterinary Science, The University of Queensland, Gatton Campus, QLD 4343, Australia.
authors: Fiona E
authors: FE
authors: Campbell
authors: School of Veterinary Science, The University of Queensland, Gatton Campus, QLD 4343, Australia.
authors: Ristan M
authors: RM
authors: Greer
authors: School of Veterinary Science, The University of Queensland, Gatton Campus, QLD 4343, Australia.
authors: Annie
authors: A
authors: Rose
authors: School of Veterinary Science, The University of Queensland, Gatton Campus, QLD 4343, Australia. Electronic address: p.mills@uq.edu.au.
authors: Paul C
authors: PC
authors: Mills
mesh_terms: D058665:Adrenergic beta-1 Receptor Agonists / Q000494:pharmacology; D058671:Adrenergic beta-1 Receptor Antagonists / Q000494:pharmacology; D000758:Anesthesia / Q000662:veterinary*; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D001262:Atenolol / Q000494:pharmacology; D002318:Cardiovascular Diseases / Q000503:physiopathology / Q000662:veterinary; D002371:Cat Diseases / Q000503:physiopathology; D002415:Cats / Q000502:physiology*; D018592:Cross-Over Studies; D004562:Electrocardiography / Q000662:veterinary; D004837:Epinephrine / Q000494:pharmacology; D005260:Female; D006339:Heart Rate / Q000187:drug effects* / Q000502:physiology*; D008297:Male; D010919:Placebos
chemical_list: D058665:Adrenergic beta-1 Receptor Agonists; D058671:Adrenergic beta-1 Receptor Antagonists; D000889:Anti-Arrhythmia Agents; D010919:Placebos; D001262:Atenolol; D004837:Epinephrine
keywords: Autonomic nervous system; Cat; Electrocardiography; Heart rate; Heart rate variability