title: Cardiac repolarization during hypoglycaemia and hypoxaemia in healthy males: impact of renin-angiotensin system activity.
abstract: OBJECTIVE
  Activity in the renin-angiotensin system (RAS) may influence the susceptibility to cardiac arrhythmia. To study the effect of basal RAS activity on cardiac repolarization during myocardial stress induced by hypoglycaemia or hypoxaemia in healthy humans.
  
  
  RESULTS
  Ten subjects with high RAS activity and 10 subjects with low RAS activity were studied on three different occasions: (i) hypoglycaemia (nadir P-glucose 2.7 +/- 0.5 mmol/L), (ii) hypoxaemia (nadir pO(2) 5.8 +/- 0.5 kPa), and (iii) normoglycaemic normoxia (control day). QT parameters were registered by Holter monitoring. Hypoglycaemia and hypoxaemia induced QTc prolongation (P < 0.001, both stimuli). The QT/RR slope and the VR increased as a function of hypoglycaemia, but were unaffected by hypoxaemia. Low RAS activity was associated with a steeper QT/RR slope in the recovery phase after both stimuli: hypoglycaemia: P = 0.04; hypoxia: P = 0.03. RAS activity had no impact on QTc [P = 0.48 (hypoglycaemia) and P = 0.40 (hypoxaemia)] or any of the other outcome variables.
  
  
  CONCLUSIONS
  Basal RAS activity has significant impact on QT dynamics, but not the corrected QT interval, during recovery from hypoglycaemia and hypoxaemia. The impact, however, is modest and more subtle than initially expected. The clinical relevance is unclear.
authors.affiliation: Endocrinology Section, Division of Internal Medicine I, Nordsjaellands Hospital - Hillerød, Helsevej 2, Hillerød DK-3400, Denmark. rsa@noh.regionh.dk
authors.forename: Rikke
authors.initials: R
authors.lastname: Due-Andersen
authors.forename: Thomas
authors.initials: T
authors.lastname: Høi-Hansen
authors.forename: Niels Vidiendal
authors.initials: NV
authors.lastname: Olsen
authors.forename: Charlotte Ellen
authors.initials: CE
authors.lastname: Larroude
authors.forename: Jørgen Kim
authors.initials: JK
authors.lastname: Kanters
authors.forename: Frans
authors.initials: F
authors.lastname: Boomsma
authors.forename: Ulrik
authors.initials: U
authors.lastname: Pedersen-Bjergaard
authors.forename: Birger
authors.initials: B
authors.lastname: Thorsteinsson
mesh_terms: D000328:Adult; D018592:Cross-Over Studies; D015716:Electrocardiography, Ambulatory; D006801:Humans; D007003:Hypoglycemia / Q000150:complications* / Q000503:physiopathology*; D000860:Hypoxia / Q000150:complications* / Q000503:physiopathology*; D007328:Insulin; D061389:Insulin, Regular, Pork; D008133:Long QT Syndrome / Q000209:etiology* / Q000503:physiopathology; D008297:Male; D010102:Oxygen Inhalation Therapy; D012084:Renin-Angiotensin System / Q000502:physiology*; D012307:Risk Factors; D016037:Single-Blind Method
chemical_list: D007328:Insulin; D061389:Insulin, Regular, Pork; C000006:insulin, neutral