title: Myocardial repolarization dispersion and autonomic nerve activity in a canine experimental acute myocardial infarction model.
abstract: BACKGROUND
  Evidence from a canine experimental acute myocardial infarction (MI) model shows that until the seventh week after MI, the relationship between stellate ganglion nerve activity (SGNA) and vagal nerve activity (VNA) progressively increases.
  
  
  OBJECTIVE
  The purpose of this study was to evaluate how autonomic nervous system activity influences temporal myocardial repolarization dispersion at this period.
  
  
  METHODS
  We analyzed autonomic nerve activity as well as QT and RR variability from recordings previously obtained in nine dogs. From a total of 48 short-term ECG segments, 24 recorded before and 24 recorded 7 weeks after experimentally-induced MI, we obtained three indices of temporal myocardial repolarization dispersion: QTe (from Q-wave to T-wave end), QTp (from Q-wave to T-wave peak), and Te (from T-wave peak to T-wave end) variability index (QTeVI, QTpVI, TeVI). We also performed heart rate variability power spectral analysis on the same segments.
  
  
  RESULTS
  After MI, all the QT variables increased QTeVI (median [interquartile range]) (from -1.76[0.82] to -1.32[0.68]), QTeVI (from -1.90[1.01] to -1.45[0.78]), and TeVI (from -0.72[0.67] to -0.22[1.00]), whereas all RR spectral indices decreased (P <.001 for all). Distinct circadian rhythms in QTeVI (P <.05,) QTpVI (P <.001) and TeVI (P <.05) appeared after MI with circadian variations resembling that of SGNA/VNA. The morning QTpVI and TeVI acrophases approached the SGNA/VNA acrophase. Conversely, the evening QTeVI acrophase coincided with another SGNA/VNA peak. After MI, regression analysis detected a positive relationship between SGNA/VNA and TeVI (R(2): 0.077; β: 0.278; p< 0.001).
  
  
  CONCLUSIONS
  Temporal myocardial repolarization dispersion shows a circadian variation after MI reaching its peak at a time when sympathetic is highest and vagal activity lowest.
authors.affiliation: Dipartimento di Scienze Cardiovascolari, Respiratorie, Nefrologiche, Anestesiologiche e Geriatriche, Policlinico Umberto I, "Sapienza" University of Rome, Rome, Italy; Krannert Institute of Cardiology, Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana. Electronic address: gianfranco.piccirillo@uniroma1.it.
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Piccirillo
authors.affiliation: Dipartimento di Scienze Cardiovascolari, Respiratorie, Nefrologiche, Anestesiologiche e Geriatriche, Policlinico Umberto I, "Sapienza" University of Rome, Rome, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Moscucci
authors.affiliation: Dipartimento di Scienze Cardiovascolari, Respiratorie, Nefrologiche, Anestesiologiche e Geriatriche, Policlinico Umberto I, "Sapienza" University of Rome, Rome, Italy.
authors.forename: Gaetana
authors.initials: G
authors.lastname: D'Alessandro
authors.affiliation: Dipartimento di Scienze Cardiovascolari, Respiratorie, Nefrologiche, Anestesiologiche e Geriatriche, Policlinico Umberto I, "Sapienza" University of Rome, Rome, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Pascucci
authors.affiliation: Dipartimento di Medicina Interna e Specialità Mediche, Policlinico Umberto I, University of Rome, Rome, Italy.
authors.forename: Pietro
authors.initials: P
authors.lastname: Rossi
authors.affiliation: Krannert Institute of Cardiology, Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana.
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: Krannert Institute of Cardiology, Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana.
authors.forename: Shien-Fong
authors.initials: SF
authors.lastname: Lin
authors.affiliation: Krannert Institute of Cardiology, Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana.
authors.forename: Peng-Sheng
authors.initials: PS
authors.lastname: Chen
authors.affiliation: Dipartimento di Medicina Clinica e Molecolare, Azienda Ospedaliera Sant' Andrea, University of Rome, Rome, Italy.
authors.forename: Damiano
authors.initials: D
authors.lastname: Magrì
mesh_terms: D000818:Animals; D002423:Cause of Death; D002940:Circadian Rhythm / Q000502:physiology*; D004195:Disease Models, Animal; D004285:Dogs; D004562:Electrocardiography; D006339:Heart Rate / Q000502:physiology; D009203:Myocardial Infarction / Q000401:mortality / Q000503:physiopathology*; D013233:Stellate Ganglion / Q000503:physiopathology*; D014630:Vagus Nerve / Q000503:physiopathology*
keywords: CF; CHF; HF; HRV; LF; LSG; MI; Myocardial infarction; SCD; SGNA; Sudden cardiac death; TP; Temporal myocardial repolarization dispersion; VLF; VNA; central frequency; congestive heart failure; heart rate variability; high frequency; left stellate ganglion; low frequency; myocardial infarction; stellate ganglion nerve activity; sudden cardiac death; total power; vagal nerve activity; very low frequency