title: Subcutaneous nerve activity is more accurate than heart rate variability in estimating cardiac sympathetic tone in ambulatory dogs with myocardial infarction.
abstract: BACKGROUND
  We recently reported that subcutaneous nerve activity (SCNA) can be used to estimate sympathetic tone.
  
  
  OBJECTIVE
  The purpose of this study was to test the hypothesis that left thoracic SCNA is more accurate than heart rate variability (HRV) in estimating cardiac sympathetic tone in ambulatory dogs with myocardial infarction (MI).
  
  
  METHODS
  We used an implanted radiotransmitter to study left stellate ganglion nerve activity (SGNA), vagal nerve activity (VNA), and thoracic SCNA in 9 dogs at baseline and up to 8 weeks after MI. HRV was determined based on time-domain, frequency-domain, and nonlinear analyses.
  
  
  RESULTS
  The correlation coefficients between integrated SGNA and SCNA averaged 0.74 (95% confidence interval [CI] 0.41-1.06) at baseline and 0.82 (95% CI, 0.63-1.01) after MI (P <.05 for both). The absolute values of the correlation coefficients were significantly larger than that between SGNA and HRV analysis based on time-domain, frequency-domain, and nonlinear analyses, respectively, at baseline (P <.05 for all) and after MI (P <.05 for all). There was a clear increment of SGNA and SCNA at 2, 4, 6, and 8 weeks after MI, whereas HRV parameters showed no significant changes. Significant circadian variations were noted in SCNA, SGNA, and all HRV parameters at baseline and after MI, respectively. Atrial tachycardia (AT) episodes were invariably preceded by SCNA and SGNA, which were progressively increased from 120th, 90th, 60th, to 30th seconds before AT onset. No such changes of HRV parameters were observed before AT onset.
  
  
  CONCLUSIONS
  SCNA is more accurate than HRV in estimating cardiac sympathetic tone in ambulatory dogs with MI.
authors.affiliation: The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; Division of Cardiology, Department of Internal Medicine, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Linkou, Taoyuan, Taiwan.
authors.forename: Yi-Hsin
authors.initials: YH
authors.lastname: Chan
authors.affiliation: The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; Division of Cardiology, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung University College of Medicine, Kaohsiung, Taiwan.
authors.forename: Wei-Chung
authors.initials: WC
authors.lastname: Tsai
authors.affiliation: Department of Biostatistics, Indiana University School of Medicine, Indianapolis, Indiana; Fairbanks School of Public Health, Indiana University, Indianapolis, Indiana.
authors.forename: Changyu
authors.initials: C
authors.lastname: Shen
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Dongsan Medical Center, Keimyung University School of Medicine, Daegu, South Korea.
authors.forename: Seongwook
authors.initials: S
authors.lastname: Han
authors.affiliation: Department of Neurology, Indiana University School of Medicine, Indianapolis, Indiana.
authors.forename: Lan S
authors.initials: LS
authors.lastname: Chen
authors.affiliation: The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; Institute of Biomedical Engineering, National Chiao-Tung University, Hsin-Chu, Taiwan.
authors.forename: Shien-Fong
authors.initials: SF
authors.lastname: Lin
authors.affiliation: The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana. Electronic address: chenpp@iu.edu.
authors.forename: Peng-Sheng
authors.initials: PS
authors.lastname: Chen
mesh_terms: D000818:Animals; D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000209:etiology; D061827:Dimensional Measurement Accuracy; D004195:Disease Models, Animal; D004285:Dogs; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods; D006339:Heart Rate; D008955:Models, Cardiovascular; D009203:Myocardial Infarction / Q000150:complications* / Q000503:physiopathology; D009431:Neural Conduction; D011237:Predictive Value of Tests; D011379:Prognosis; D013223:Statistics as Topic; D013233:Stellate Ganglion / Q000503:physiopathology*; D013610:Tachycardia / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D013900:Thoracic Nerves / Q000503:physiopathology; D014630:Vagus Nerve / Q000503:physiopathology*
keywords: Atrial arrhythmia; Autonomic nervous system; Heart rate variability; Myocardial infarction; Subcutaneous nerve activity